机械加工毕业设计外文翻译--微孔的加工方法

毕业设计中英文翻译英文原文Hard gear processing[abstract ]uses in the power drive gear and the gear box, its size request smaller, the gear drive noise is lower, thus causes to the hard gear demand, also gave the gear manufacturer to propose explored the gear to process the new method the request OutlineUses in the power drive gear and the gear box, its size request smaller, the gear drive noise is lower, thus causes to the hard gear demand, also gave the gear manufacturer to propose explored the gear to process the new method the request. The gear in the hard heat treatment process, its material organization and the stress change, usually can cause the gear to have the distortion, namely tooth profile, tooth to and tooth pitch error. This this error will cause the tooth profile not correctly to mesh in the transmission time, thus has enlarged the load, will have the gear noise. Therefore, the hard gear after the heat treatment, should increase together the precision work working procedure generally.The hard gear precision work craft may divide into two kinds: A kind is uses non- formed the cutting edge, like the gear rubs truncates the processing; Another kind then is has formed the cutting edge like hard gear (HRC48 ~ 53) to roll truncates the processing.This article strongly will discuss will use in hardly rolling the hard alloy tools forming cutting edge precision work process which the tooth will process. The now hard alloy material, the cutting tool coating and the gear-hobbing machine technology development, has caused the hard gear to roll cuts the processing technology to have the remarkable enhancement, specially is smaller than in the processing or was equal to when 12DP center small modulus gear, may withstand the enormous cutting force which in the hard cutting process produces.Hard alloy hob selectionThe hard alloy hob has the very big progress in the material variety specification. Superfine, is thin, medium or the big pellet hard alloy now all has the product. In addition, the hard alloy hob semifinished materials formed craft technology also had the remarkable enhancement, like uses static pressure and so on heat (HIP) the craft, this craft under the high-pressured high temperature, increased the hard alloy semifinished materials intrinsic binding force, enhanced the hard alloy anti- curved intensity. According to the ISO stipulation, the entity hard alloy material may differently divide into certain kinds according to the application situation: The gear cutting tool divides into K kind and P kind, K kind of hard alloy has a higherresistance to wear, P kind then has the better high temperature red hardness. In the K trademark and in the P trademark hard alloy, each kind of trademark hard alloy granular structure is different, from medium pellet to superfine pellet. Each kind of trademark all has its application situation, this is and the granular structure is connected. Generally speaking, regarding softly rolls truncates, the K analogy P kind of performance is friends with, K kind of hard alloy can obtain a micron level the granular structure (granularity to be smaller than 0.5 mu m), but P kind then is not good. In abrasion aspect, K kind of toughness better, the life is longer.The hob resharpens and renovatesAfter the hob processing certain quantity work piece, its cutting edge failure, this time must resharpen. Sharpens the after hob to have to maintain the original geometry shape; The cutting edge must be sharp; The cutting tool golden phase structure cannot because rub truncates the heat but to destroy. Thus when sharpens the hard alloy hob should use one kind of oil base refrigerant, it does not get up to the chlorine and the sulfur the response. Regarding scrapes the hob, sharpens after the coating not likely to use in hob such which the entity semifinished materials hardly rolls being important again. After the hard alloy hob sharpens in front of the coating, suggested carries on the pretreatment to its cutting edge.The hob rewill sharpen can except the cutting surface original coating, this will be able to reduce the cutting tool life. The cutting tool is may again spread. Usually regarding the TiN coating, may spread 3 ~ 4; Says regarding TiCN and the TiALN coating, because coating itself has the very big internal stress, therefore on cutting edge with difficulty again again coating. After several spreading TiN coating, can have the height non-uniformity condition, and influentials the tendency which the level falls off, therefore the original coating must remove.At present has two methods to be possible to remove the cutting tool coating: Chemistry draws back spreads draws back with physics spreads. Draws back with chemistry spreads removes on the hard alloy tools the coating is one kind of fine craft, requests the operator to have the suitable level of expertise. The excessively chemistry draws back spreads not only removes the coating, moreover also will dissolve washes the cobalt cement, the damage hard alloy material microscopic structure. The cutting edge microscopic damage will produce the zigzag surface. In addition, when draws back spreads must to the hob pillow block, in the hole and the sign carries on the protection, in order to avoid damages. But physics spreads, then must carry on by the original cutting tool factory, it involves to puts in order rerubs the hob tooth profile truncates. Although draws back chemistry spreads must be much more expensive than, but obtains is a new hob, the quality and the life all can obtain the guarantee.To gear-hobbing machine requestIn order to fully displays the hard alloy and the coating craft merit, the gear-hobbing machine should do correspondingly improves. At present all advanced gear-hobbing machines all press high speed roll the tooth to carry on the design, its gear-hobbing machine hob rotational speed surpasses 3000r/Min, usually is5000r/Min, the work piece main axle rotational speed and the hob rotational speed match. In addition, the engine bed has very high moves the rigidity and the hot rigidity. The advanced gear-hobbing machine some main design characteristics are: Uses the compound epoxy resin lathe bed, by improves the engine bed the tendency and the static characteristic; Has the constant temperature installment the high speed hob headstock; High speed work piece main axle; May use does, the wet two kinds rolls truncates the craft; Belt electro-optical sensor digital actuation system; The straight line rolls the guide rail system; High speed automatic high-quality goods (2 ~ 3 seconds); The occupying a land area of is compact; According to man-machine engineering design; Services conveniently.Uses scrapes the craftRegardless of is the mechanical type the CNC gear-hobbing machine all can carry on scrapes, but the condition is the engine bed must equip has the work piece to the cutting tool selsyn train system. This may cause to scrape the craft economically, to has on the automatic yummy treats system the engine bed very to be also important. The electronic non- contact system depends on a simulation quantity sensor to send out the pulse to survey the cutting tool main axle, the work piece main axle and the gear position. The engine bed CNC controller carries on processing to these pulses, then is opposite to the work piece main axle in the cutting tool position carries on the adjustment, causes a work piece turn of tooth and the hob knife tooth relative position relations is correct.In scrapes in the craft to have very many merits with the refrigerant: In scrapes in the process, the refrigerant has provided the lubricating ability; Because scrapes produces is not the normal scrap, the temperature control is extremely important. Blows the scrap small is thin, does not look like normal knife filings such to be possible to carry off many quantity of heats, therefore scrapes time uses the refrigerant to be possible to control the cutting tool, the work piece and the engine bed system temperature; The refrigerant may washes away the scrap from the cutting tool and the work piece; Improved the work piece surface fine roughness; Enhanced the cutting tool life."Rolls in the green truncates" in the craft, correctly chooses the tooth thick remainder is very important. The recommendation choice down milling rolls the tooth, because it may obtain the thickest scrap, this is helpful to the control cutting process dynamic condition, enhances the cutting tool life. The experience proved that, the cutting speed may surpass 200m/Min, enters for the quantity choice is decided by the superficially attractive fineness which must achieve. The model enters for the scope is 0.5 ~ 1.25mm/R. The cutting tool shifts (flees knife) the method very to be also important, because scrapes time only then the rough machining section partial cutting edges only then undergo the attrition. On the contrary, in "the green cutting" in the process, the cutting tool precision work has partially undertaken the main process load. This meant when scraping flees the knife quantity to be supposed to be bigger, when like the gear is 12 ~ 48DP, each time flees the knife quantity is 0.3 ~ 0.4mm.Scrapes the hob the selectionScrapes the hard alloy hob to divide into two big kinds: Uses in 10DP or the bigger modulus hob, usually all designs has a negative rake front the cutting, when the cutting edge contacts to the hard tooth face, reduced to the hard alloy material impact; Regarding the small modulus gear, does not need to have the negative rake. The negative rake hob shortcoming is sharpens the difficulty. After the hob sharpens the outer diameter to reduce, in order to obtain the correct negative rake to be supposed to change the grinding wheel the bias quantity.When scrapes, the big modulus gear, its addendum, the outer annulus diameter and the tooth root spot all are usually not rolled truncates, and has a smooth transition a request turn of tooth to the tooth root. In order to obtain sinks cuts with the integrity transition circular arc radius, enhances the tooth root the anti- curved intensity, uses in the big modulus gear ideal scraping the hob to be supposed to have the flange. Regarding the small modulus gear processing, should use the standard hob. Uses the standard in front of the radial direction the angle hard alloy hob processing to be called "the hard alloy hob to roll again cuts", but is not "scrapes", latter referred has used a negative rake hob.Hardly rolls the specification which truncates and hardly scrapes the specification which, or the hard alloy hob rolls again truncates nearly same, similarity is uses the strategy which flees the knife to shift to be different. When hardly rolls, the scrap excision must spend the massive energies. This energy finally becomes the quantity of heat. Tries to carry off very important these thermal sending out. After the suggestion processes a work piece every time, the hob flees a position entire tooth pitch. When the hob will flee from beginning to end the position from now on, will be supposed to transfer to the hob to the initial position has a bias quantity the spot. This bias quantity is decided by the hob design and the application, its goal is for be helpful to the hob uniform wear. Another one similarity is the attire which uses clamps the system. As a result of the enormous cutting force, the jig must safely clamp the work piece. The processing result indicated that, the identical helical gear when hardly rolls again with the hard alloy hob, its gear quality is very high, the tooth profile approaches the AGMA10 level, the tooth to surpasses the AGMA12 level with the tooth pitch; The entire hard semifinished materials hardly roll cut the processing the helical gear, its gear precision extremely is also high, the tooth profile precision may reach the AGMA10 level, the tooth to may achieve the AGMA12 level with the tooth pitch. ConclusionAt present has explored many economies the method to process the hard gear, including the material choice, the soft processing method, the heat treatment craft and the hard precision work, enable the hard gear to obtain the popularization, has satisfied the high grade transmission device to the hard gear request.Carries on from entity entire hard work piece semifinished materials hardly rolls cuts the processing is one kind of new processing craft. Because has a rigid better engine bed and the high quality hard alloy tools material and performs coating processing, causes hardly to roll slivers is one effective processing method. Indicatedfrom the factory practical application result that, the hard gear rolls cuts (hardly rolls) the craft to have the broad application prospect.译文：淬硬齿轮的加工【摘要】用于动力传动的齿轮和齿轮箱，其尺寸要求更小，齿轮传动的噪音更低，从而导致对淬硬齿轮的需求，也给齿轮制造厂家提出了探索齿轮加工新方法的要求.概述用于动力传动的齿轮和齿轮箱，其尺寸要求更小，齿轮传动的噪音更低，从而导致对淬硬齿轮的需求，也给齿轮制造厂家提出了探索齿轮加工新方法的要求。

题目机械加工介绍学院专业班级姓名学号指导教师Machining Processing Introduction1 LatheLathes are machine tools designed primarily to do turning, facing and bori ng, Very little turning is done on other types of machine tools, and none can do it with equal facility. Because lathes also can do drilling and reaming, their versatility permits several operations to be done with a single setup of the work piece. Consequently, more lathes of various types are used in manufacturing than any other machine tool.The essential components of a lathe are the bed, headstock assembly, tailstock assembly, and the leads crew and feed rod.The bed is the backbone of a lathe. It usually is made of well normalized or aged gray or nodular cast iron and provides s heavy, rigid frame on which all the other basic components are mounted. Two sets of parallel, longitudinal ways, inner and outer, are contained on the bed, usually on the upper side. Som makers use an inverted V-shape for all four ways, whereas others utilize one inverted V and one flat way in one or both sets, they are precision-machined to assure accuracy of alignment. On most modern lathes the way are surface-hardened to resist wear and abrasion, but precaution should be taken in operating a lathe to assure that the ways are not damaged. Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed.The headstock is mounted in a foxed position on the inner ways, usually at the left end of the bed. It provides a powered means of rotating the word at various speeds. Essentially, it consists of a hollow spindle, mounted in accurate bearings, and a set of transmission gears-similar to a truck transmission—through which the spindle can be rotated at a number of speeds. Most lathes provide from 8 to 18 speeds, usually in a geometric ratio, and on modern lathes all the speeds can be obtained merely by moving from two to four levers. An increasing trend is to provide a continuously variable speed range through electrical or mechanical drives.Because the accuracy of a lathe is greatly dependent on the spindle, it is of heavy construction and mounted in heavy bearings, usually preloaded tapered roller or ball types. The spindle has a hole extending through its length through which long bar stock can be fed. The size of maximum size of bar stock that can be machined when the material must be fed through spindle.The tailsticd assembly consists, essentially, of three parts. A lower casting fits on the inner ways of the bed and can slide longitudinally thereon, with means for clamping the entire assembly in any desired location; an upper casting fits on the lower one and can be moved transversely upon it, on some type of keyed ways, to permit aligning the assembly is the tailstock quill. This is hollow steel cylinder, usually about 51 to 76mm (2to 3 inches) in diameter, that can be moved several inches longitudinally in and out of the upper casting by means of a hand wheel and screw.The size of a lathe is designated by two dimensions. The first is known as theswing. This is the maximum diameter of work that can be rotated on a lathe. It is approximately twice the distance between the line connecting the lathe centers and the nearest point on the ways, the second size dimension is the maximum distance between centers. The swing thus indicates the maximum work piece diameter that can be turned in the lathe, while the distance between centers indicates the maximum length of work piece that can be mounted between centers.Engine lathes are the type most frequently used in manufacturing. They are heavy-duty machine tools with all the components described previously and have power drive for all tool movements except on the compound rest. They commonly range in size from 305 to 610 mm(12 to 24 inches)swing and from 610 to 1219 mm(24 to 48 inches) center distances, but swings up to 1270 mm(50 inches) and center distances up to 3658mm(12 feet) are not uncommon. Most have chip pans and a built-in coolant circulating system. Smaller engine lathes-with swings usually not over 330 mm (13 inches) –also are available in bench type, designed for the bed to be mounted on a bench on a bench or cabinet.Although engine lathes are versatile and very useful, because of the time required for changing and setting tools and for making measurements on the work piece, thy are not suitable for quantity production. Often the actual chip-production tine is less than 30% of the total cycle time. In addition, a skilled machinist is required for all the operations, and such persons are costly and often in short supply. However, much of the operator’s time is consumed by simple, repetitious adjustments and in watching chips being made. Consequently, to reduce or eliminate the amountof skilled labor that is required; turret lathes, screw machines, and other types of semiautomatic and automatic lathes have been highly developed and are widely used in manufacturing.2 Numerical ControlOne of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control (NC). Prior to the advent of NC, all machine tools ere manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than the limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools.Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions. Rather than operating a machine tool, an NC technician writes a program that issues operational instructions to the machine tool. For a machine tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The development of NC led to the development of several other innovations in manufacturing technology:Electrical discharge machining, Laser cutting, Electron beam welding.Numerical control has also made machine tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tolls and processes.Like so many advanced technologies, NC was born in the laboratories of the Massachusetts Institute of Technology. The concept of NC was developed in the early 1950s with funding provided by the U.S. Air Force. In its earliest stages, NC machines were able to made straight cuts efficiently and effectively.However, curved paths were a problem because the machine tool had to be programmed to undertake a series of horizontal and vertical steps to produce a curve. The shorter the straight lines making up the steps, the smoother is the curve, each line segment in the steps had to be calculated.This problem led to the development in 1959 of the Automatically Programmed Tools (APT) language. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the fur ther development from those used today. The machines had hardwired logic circuits. The instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape. Atape reader was used to interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development.A major problem was the fragility of the punched paper tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each successive time a part was produced on a machine tool; the paper tape carrying the programmed instructions had to be rerun through the reader. If it was necessary to produce 100 copies of a given part, it was also necessary to run the paper tape through the reader 100 separate tines. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use.This led to the development of a special magnetic plastic tape. Whereas the paper carried the programmed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than the paper tape, which solved the problem of frequent tearing and breakage. However, it still left two other problems.The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it was necessary to interrupt machining operations and make a new tape. It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became areality and soon solved the problems of NC associated with punched paper and plastic tape.The development of a concept known as direct numerical control (DNC) solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control, machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool an needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend on a host computer. When the host computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.3 TurningThe engine lathe, one of the oldest metal removal machines, has a number of useful and highly desirable attributes. Today these lathes are used primarily in small shops where smaller quantities rather than large production runs are encountered.The engine lathe has been replaced in today’s production shops by a wide variety of automatic lathes such as automatic of single-point tooling for maximum metal removal, and the use of form tools for finish on a par with the fastest processing equipment on the scene today.Tolerances for the engine lathe depend primarily on the skill of the operator. The design engineer must be careful in using tolerances of an experimental part that has been produced on the engine lathe by a skilled operator. In redesigning an experimental part for production, economical tolerances should be used.Turret Lathes Production machining equipment must be evaluated now, more than ever before, this criterion for establishing the production qualification of a specific method, the turret lathe merits a high rating.In designing for low quantities such as 100 or 200 parts, it is most economical to use the turret lathe. In achieving the optimum tolerances possible on the turrets lathe, the designer should strive for a minimum of operations.Automatic Screw Machines Generally, automatic screw machines fall into several categories; single-spindle automatics, multiple-spindle automatics and automatic chucking machines. Originally designed for rapid, automatic production of screws and similar threaded parts, the automatic screw machine has long since exceeded the confines of this narrow field, and today plays a vital role in the mass production of a variety of precision parts. Quantities play an important part in the economy of the parts machined on the automatic screw machine. Quantities less than on the automatic screw machine. The cost of the parts machined can be reduced if the minimum economical lot size is calculated and the proper machine is selected for these quantities.Automatic Tracer Lathes Since surface roughness depends greatly on material turned, tooling , and feeds and speeds employed, minimum tolerances that can be held on automatic tracer lathes are not necessarily the most economical tolerances.In some cases, tolerances of 0.05mm are held in continuous production using but one cut . groove width can be held to 0.125mm on some parts. Bores and single-point finishes can be held to 0.0125mm. On high-production runs where maximum output is desirable, a minimum tolerance of 0.125mm is economical on both diameter and length of turn.机械加工介绍1.车床车床主要是为了进行车外圆、车端面和镗孔等项工作而设计的机床。

外文原文Options for micro-holemakingAs in the macroscale-machining world, holemaking is one of the most— if not the most—frequently performed operations for micromachining. Many options exist for how those holes are created. Each has its advantages and limitations, depending on the required hole diameter and depth, workpiece material and equipment requirements. This article covers holemaking with through-coolant drills and those without coolant holes, plunge milling, microdrilling using sinker EDMs and laser drilling.Helpful HolesGetting coolant to the drill tip while the tool is cutting helps reduce the amount of heat at the tool/workpiece interface and evacuate chips regardless of hole diameter. Butthrough-coolant capability is especially helpful when deep-hole microdrilling because the tools are delicate and prone to failure when experiencing recutting of chips, chip packing and too much exposure to carbide’s worst enemy—heat.When applying flood coolant, the drill itself blocks access to the cutting action. “Somewhere about 3 to 5 diameters deep, the coolant has trouble getting down to the tip,” said Jeff Davis, vice president of engineering for Harvey Tool Co., Rowley, Mass. “It becomes wise to use a coolant-fed drill at that point.”In addition, flood coolant can cause more harm than good when microholemaking. “The pressure from the flood coolant can sometimes snap fragile drills as they enter the part,” Davis said.The toolmaker offers a line of through-coolant drills with diameters from 0.039" to 0.125" that are able to produce holes up to 12 diameters deep, as well as microdrills without coolant holes from 0.002" to 0.020".Having through-coolant capacity isn’t enough, though. Coolant needs to flow at a rate that enables it to clear the chips out of the hole. Davis recommends, at a minimum, 600 to 800 psi of coolant pressure. “It works much better if you have higher pressure than that,” he added.To prevent those tiny coolant holes from becoming clogged with debris, Davis also recommends a 5μm or finer coolant filter.Another recommendation is to machine a pilot, or guide, hole to prevent the tool from wandering on top of the workpiece and aid in producing a straight hole. When applying a pilot drill, it’s important to select one with an included angle on its point that’s equal to or larger than the included angle on the through-coolant drill that follows. The pilot drill’sdiameter should also be slightly larger. For example, if the pilot drill has a 120° included angle and a smaller diameter than a through-coolant drill with a 140° included angle, “then you’re catching the coolant-fed drill’s corners and knocking those corners off,” Davis said, which damages the drill.Although not mandatory, pecking is a good practice when microdrilling deep holes. Davis suggests a pecking cycle that is 30 to 50 percent of the diameter per peck depth, depending on the workpiece material. This clears the chips, preventing them from packing in the flute valleys.Lubricious ChillTo further aid chip evacuation, Davis recommends applying an oil-based metalworking fluid instead of a waterbased coolant because oil provides greater lubricity. But if a shop prefers using coolant, the fluid should include EP (extreme pressure) additives to increase lubricity and minimize foaming. “If you’ve got a lot of foam,” Davis noted, “the chips aren’t being pulled out the way they are supposed to be.”He added that another way to enhance a tool’s slipperiness while extending its life is with a coating, such as titanium aluminum nitride. TiAlN has a high hardness and is an effective coating for reducing heat’s impact when drilling difficult-to-machine materials, like stainless steel.David Burton, general manager of Performance Micro Tool, Janesville, Wis., disagrees with the idea of coating microtools on the smaller end of the spectrum. “Coatings on tools below 0.020" typically have a negative effect on every machining aspect, from the quality of the initial cut to tool life,” he said. That’s because coatings are not thin enough and negatively alter the rake and relief angles when applied to tiny tools.However, work continues on the development of thinner coatings, and Burton indicated that Performance Micro Tool, which produces microendmills and microrouters and resells microdrills, is working on a project with others to create a submicron-thickness coating. “We’re probably 6 months to1 year from testing it in the market,” Burton said.The microdrills Performance offers are basically circuit-board drills, which are also effective for cutting metal. All the tools are without through-coolant capability. “I had a customer drill a 0.004"-dia. hole in stainless steel, and he was amazed he could do it with a circuit-board drill,” Burton noted, adding that pecking and running at a high spindle speed increase the drill’s effectiveness.The requirements for how fast microtools should rotate depend on the type of CNC machines a shop uses and the tool diameter, with higher speeds needed as the diameter decreases. (Note: The equation for cutting speed is sfm = tool diameter × 0.26 × spindlespeed.)Although relatively low, 5,000 rpm has been used successfully by Burton’s customers. “We recommend that our customers find the highest rpm at the lowest possible vibration—the sweet spot,” he said.In addition to minimizing vibration, a constant and adequate chip load is required to penetrate the workpiece while exerting low cutting forces and to allow the rake to remove the appropriate amount of material. If the drill takes too light of a chip load, the rake face wears quickly, becoming negative, and tool life suffers. This approach is often tempting when drilling with delicate tools.“If the customer decides he wants to baby the tool, he takes a lighter chip load,” Burton said, “and, typically, the cutting edge wears much quicker and creates a radius where the land of that radius is wider than the chip being cut. He ends up using it as a grinding tool, trying to bump material away.” For tools larger than 0.001", Burton considers a chip load under0.0001" to be “babying.” If the drill doesn’t snap, premature wear can result in abysmal tool life.Too much runout can also be destructive, but how much is debatable. Burton pointed out that Performance purposely designed a machine to have 0.0003" TIR to conduct in-house, worst-case milling scenarios, adding that the company is still able to mill a 0.004"-wide slot “day in and day out.”He added: “You would think with 0.0003" runout and a chip load a third that, say,0.0001" to 0.00015", the tool would break immediately because one flute would be taking the entire load and then the back end of the flute would be rubbing.When drilling, he indicated that up to 0.0003" TIR should be acceptable because once the drill is inside the hole, the cutting edges on the end of the drill continue cutting while the noncutting lands on the OD guide the tool in the same direction. Minimizing run out becomes more critical as the depth-to-diameter ratio increases. This is because the flutes are not able to absorb as much deflection as they become more engaged in the workpiece. Ultimately, too much runout causes the tool shank to orbit around the tool’s center while the tool tip is held steady, creating a stress point where the tool will eventually break.Taking a PlungeAlthough standard microdrills aren’t generally available below 0.002", microendmills that can be used to “plunge” a hole are. “When people want to drill smaller than that, they use our endmills and are pretty successful,” Burton said. However, the holes can’t be very deep because the tools don’t have long aspect, or depth-to-diameter, ratios. Therefore, a 0.001"-dia. endmill might be able to only make a hole up to 0.020" deep whereas a drill of the same sizecan go deeper because it’s designed to place the load on its tip when drilling. This transfers the pressure into the shank, which absorbs it.Performance offers endmills as small as 5 microns (0.0002") but isn’t keen on increasing that line’s sales. “When people try to buy them, I very seriously try to talk them out of it because we don’t like making them,” Burton said. Part of the problem with tools that small is the carbide grains not only need to be submicron in size but the size also needs to be consistent, in part because such a tool is comprised of fewer grains. “The 5-micron endmill probably has 10 grains holding the core together,” Burton noted.He added that he has seen carbide powder containing 0.2-micron grains, which is about half the size of what’s commercially available, but it also contain ed grains measuring 0.5 and 0.6 microns. “It just doesn’t help to have small grains if they’re not uniform.”MicrovaporizationElectrical discharge machining using a sinker EDM is another micro-holemaking option. Unlike , which create small holes for threading wire through the workpiece when wire EDMing, EDMs for producing microholes are considerably more sophisticated, accurate and, of course, expensive.For producing deep microholes, a tube is applied as the electrode. For EDMing smaller but shallower ho les, a solid electrode wire, or rod, is needed. “We try to use tubes as much as possible,” said Jeff Kiszonas, EDM product manager for Makino Inc., Auburn Hills, Mich. “But at some point, nobody can make a tube below a certain diameter.” He added that some suppliers offer tubes down to 0.003" in diameter for making holes as small as 0.0038". The tube’s flushing hole enables creating a hole with a high depth-to-diameter ratio and helps to evacuate debris from the bottom of the hole during machining.One such sinker EDM for producing holes as small as 0.00044" (11μm) is Makino’s Edge2 sinker EDM with fine-hole option. In Japan, the machine tool builder recently produced eight such holes in 2 minutes and 40 seconds through 0.0010"-thick tungsten carbide at the hole locations. The electrode was a silver-tungsten rod 0.00020" smaller than the hole being produced, to account for spark activity in the gap.When producing holes of that size, the rod, while rotating, is dressed with a charged EDM wire. The fine-hole option includes a W-axis attachment, which holds a die that guides the electrode, as well as a middle guide that prevents the electrode from bending or wobbling as it spins. With the option, the machine is appropriate for drilling hole diameters less than 0.005".Another sinker EDM for micro-holemaking is the Mitsubishi VA10 with a fine-holejig attachment to chuck and guide the fine wire applied to erode the material. “It’s a standardEDM, but with that attachment fixed to the machine, we can do m icrohole drilling,” said Dennis Powderly, sinker EDM product manager for MC Machinery Systems Inc., Wood Dale, Ill. He added that the EDM is also able to create holes down to 0.0004" using a wire that rotates at up to 2,000 rpm.Turn to TungstenEDMing is typically a slow process, and that holds true when it is used for microdrilling. “It’s very slow, and the finer the details, the slower it is,” said , president and owner of Optimation Inc. The Midvale, Utah, company builds Profile 24 Piezo EDMs for micromachining and also performs microEDMing on a contract-machining basis.Optimation produces tungsten electrodes using a reverse-polarity process and machines and ring-laps them to as small as 10μm in diameter with 0.000020" roundness. Applying a10μm-dia. electrode produces a hole about 10.5μm to 11μm in diameter, and blind-holes are possible with the company’s EDM. The workpiece thickness for the smallest holes is up to 0.002", and the thickness can be up to 0.04" for 50μm holes.After working with lasers and then with a former EDM builder to find a better way to produce precise microholes, Jorgensen decided the best approach was DIY. “We literally started with a clean sheet of paper and did all the electronics, all the software and the whole machine from scratch,” he said. Including the software, the machine costs in the neighborhood of $180,000 to $200,000.Much of the company’s contract work, which is provided at a shop rate of $100 per hour, involves microEDMing exotic metals, such as gold and platinum for X-ray apertures, stainless steel for optical applications and tantalum and tungsten for the electron-beam industry. Jorgensen said the process is also appropriate for EDMing partially electrically conductive materials, such as PCD.“The customer normally doesn’t care too much about the cost,” he said. “We’ve done parts where there’s $20,000 [in time and material] involved, and you can put the whole job underneath a fingernail. We do everything under a microscope.”Light CuttingBesides carbide and tungsten, light is an appropriate “tool material” formicro-holemaking. Although most laser drilling is performed in the infrared spectrum, the SuperPulse technology from The Ex One Co., Irwin, Pa., uses a green laser beam, said Randy Gilmore, the comp any’s director of laser technologies. Unlike the femtosecond variety, Super- Pulse is a nanosecond laser, and its green light operates at the 532-nanometer wavelength. The technology provides laser pulses of 4 to 5 nanoseconds in duration, and those pulses are sent in pairs with a delay of 50 to 100 nanoseconds between individual pulses. The benefits of this approach are twofold. “It greatly enhances material removal compared to other nanosecond lasers,” Gilmore said, “and greatly reduces the amount of ther mal damagedone to the workpiece material” because of the pulses’ short duration.The minimum diameter produced with the SuperPulse laser is 45 microns, but one of the most common applications is for producing 90μm to 110μm holes in diesel injector nozzles made of 1mm-thick H series steel. Gilmore noted that those holes will need to be in the 50μm to 70μm range as emission standards tighten because smaller holes in injector nozzles atomize diesel fuel better for more efficient burning.In addition, the technology can produce negatively tapered holes, with a smaller entrance than exit diameter, to promote better fuel flow.Another common application is drilling holes in aircraft turbine blades for cooling. Although the turbine material might only be 1.5mm to 2mm thick, Gilmore explained that the holes are drilled at a 25° entry angle so the air, as it comes out of the holes, hugs the airfoil surface and drags the heat away. That means the hole traverses up to 5mm of material. “Temperature is everything in a turbine” he said, “because in an aircraft engine, the hotter you can run the turbine, the better the fuel economy and the more thrust you get.”To further enhance the technology’s competitiveness, Ex One developed apatent-pending material that is injected into a hollow-body component to block the laser beam and prevent back-wall strikes after it creates the needed hole. After laser machining, the end user removes the material without leaving remnants.“One of the bugaboos in getting lasers accepted in the diesel injector community is that light has a nasty habit of continuing to travel until it meets another object,” Gilmore said. “In a diesel injector nozzle, that damages the interior surface of the opposite wall.”Although the $650,000 to $800,000 price for a Super- Pulse laser is higher than amicro-holemaking EDM, Gilmore noted that laser drilling doesn’t require electrodes. “A laser system is using light to make holes,” he said, “so it doesn’t have a consumable.”Depending on the application, mechanical drilling and plunge milling, EDMing and laser machining all have their place in the expanding micromachining universe. “People want more packed into smaller spaces,” said Makino’s Kiszonas.中文翻译微孔的加工方法正如宏观加工一样，在微观加工中孔的加工也许也是最常用的加工之一。

英文原文Gear manufacturing methodsThere are two basic methods of manufacturing gear teeth: the generating process and the forming process. when a gear tooth is generated, the workpiece and the cutting or grinding tool are in continuous mesh and the tooth form is generated by the tool. In other words, the work and the tool are conjugated to each other. hobbing :machines, shaper cutters, shaving machines, and grinders use this principle.When a gear tooth is formed, the tool is in the shape of the space that is being machined out. Some grinding machines use this principle with an indexing mechianism which allows the gear teeth to be formed tooth by tooth. Broaches are examples of form tools that machine all the gear teeth simultaneously.shapingShaping is inherently similar to planning but uses a circular cuttrer instead of rack and the resulting reduction in the reciprocating inertia allows much higher stroking speeds: modern shapers cutting car gears can run at 2,000 cutting strokes per minmute. The shape of the cutter is roughly the same as an involute gear but the tips of the teeth are rounded.The generating drive between cutter and workpiece does not involve a rack or leadscrew since only circular motion in involved. The tool and workpiece move tangential typically 0.5 mm for each stroke of the cutter. On the return stroke the cutter must be retracted about 1 mm to give clearance otherwise tool rub occurs on the backstroke and failure is rapid. The speed on this type of machine is limited by the rate at which some 50kg of cutter and bearings can be moved a distance of 1 mm. the accelerations involved tequire forces of the order of 5000N yet high accuracy must be maintained.The advantages of shaping are that production rates are relatively high and that it is possible to cut right up to a shoulder. Unfortunately, for helical gears, a helical guide is required to impose a rotational motion on the stroking motion; such helical guides cannot be produced easily or cheaply so the method is only suitable for long runs with helical gears since special cutters and guides must be manufactured for each different helix angle. A great advantage of shaping is its ability to annular gears such as those required for large epicyclie drives.When very high accuracy is of importance the inaccuracies in the shaping cutter matter since they may transfer to the cut gear. It is obvious that profile errors will transfer but it is less obvious than an eccentrically mounted or ground cutter will give a characteristic “dropped tooth”. There are several causes for “dropped tooth” but it occurs most commonly when the diameter of the workpiece is about half, one and half, two and a half, etc, times the cutter diameter. If the cutter starts on a high point and finishes on a low point during the final finishing revolution of the gear the peak to peak eccentricity errors in the cutter occurs between the last and the first tooth of the final revolution of the cut gear; as the cumulative pitch error of the cutter may well be over 25 microns there is a sudden pitch error of this amount on the cut gear. The next gear cut on the machine may however be very good on adjacent pitch if the final cut happened to start in a favorable position on the cutter.Various attempts have been made to prevent this effect, in particular by continuing rotation without any further cutter infeed but if the shaping machine is not very rigid and the cutter very sharp then no further cutting will occur and the error will not be removed.hobbinghobbing, the most used metal cutting method, uses the rack generating principle but avoids slow reciprocation by mounting many “racks ” on a rotating cutter. The “racks” are displaced axially to form a gashed worm. The “racks” do not generate the correct involute shape for the whole length of the teeth since they are moving on a circular path and so the hob is fed slowly along the teeth either axially in normal or in the direction of the helix in “oblique” hobbing.Metal removal rates are high since no reciprocation of hob or workpiece is required and so cutting speeds of 40 m/min can be used for conventional hobs and up to 150m/min for carbide hobs. Typically with a 100mm diameter hob the rotation speed will be 100rpm and so a twenty tooth workpiece will rotate at 5 rpm. Each revolution of the workpiece will correspond to 0.75mm feed so the hob will advance through the workpiece at about 4mm per minute. For car production roughing multiple start hobs can be used with coarse feeds of 3mm per revolution so that 100 rpm on the cutter, a two-start hob and a 20 tooth gear will give a feed rate of 30mm/minute.The disadvantage of a coarse feed rate is that a clear marking is left on the workpiece, particularly in the root, showing a pattern at a spacing of the feed rate per revolution. This surface undulation is less marked on the flanks than in the root and is not important when there is a subsequent finishing operation such as shaving or grinding. When there are no further operations the feed per revolution must be restricted to keep the undulations below a limit which is usually dictated by lubrication conditions. The height of the undulations in the root of the gear is given by squaring the feed per revolution and dividing by four times the diameter of the hob; 1 mm feed and 100mm diameter gives 2.5 micron high undulations in the root. On the gear flank the undulation is roughly cos70 as large, i.e., about 0.85 micron.Accuracy of hobbing is normally high for pitch and for helix, provided machines are maintained; involute is dependent solely on the accuracy of the hob profile. As the involute form is generated by as many cuts as there are gashes on the hob the involute is not exact, but if there are, say, 14 tangents generating a flank of 20 mm radius curvature about 4 mm high the divergence from a true involute is only about half a micron; hob manufacturing and mounting errors can be above 10 microns. Use of twostart hobs or oblique hobbing gives increased error levels since hob errors of pitching transfer to the cut gear.broachingBroaching is not used for helical gears but is useful for internal spur gears; the principal use of broaching in this context is for internal splines which cannot easily be made by any other method. As with all broaching the method is only economic for large quantities since setup costs are high.The major application of broaching techniques to helical external gears is that used by Gleasons in their G-TRAC machine .this machine operates by increasing the effective radius of a hobbing cutter to infinity so that each tooth of the cutter is travelingin a straight line instead of on a radius. This allows the cutting action to extend over the whole facewidth of a gear instead of the typical 0.75 mm feed per revolution of hobbing. The resulting process gives a very high production rate , more suitable for U.S.A. production volumes than for the relatively low European volumes and so, despite a high initial cost ,is very competitive.Broaching give high accuracy and good surface finish but like all cutting processes is limited to “soft” materials which must be subsequently casehardened or heat treated, giving distortion.ShavingA shaving cutting cutter looks like a gear which has extra clearance at the root and whose tooth flanks have been grooved to give cutting edges. It is run in mesh with the rough gear with crossed axes so that there is in theory point contact with a relative velocity along the teeth giving scraping action. The shaving cutter teeth are relatively flexible in bending and so will only operate effectively when they are in double contact between two gear teeth. The gear and cutter operate at high rotational speeds with traversing of the workface and about 100 mm micron of material is removed. Cycle times can be less than half a minute and the machines are not expensive but cutters are delicate and difficult to manufacture. It is easy to make adjustments of profile at the shaving stage and crowning can be applied. Shaving can be carried out near a shoulder by using a cutter which is plunged in to depth without axial movement; this method is fast but requires more complex cutter design.grindingGrinding is extremely important because it is the main way hardened gear are machined. When high accuracy is required it is not sufficient to pre-correct for heat treatment distortion and grinding is then necessary.The simplest approach to grinding, often termed the Orcutt method. The wheel profile is dressed accurately to shape using single point diamonds which are controlled by templates cut to the exact shape required; 6:1 scaling with a pantograph is often used. The profile wheel is then reciprocated axially along the gear which rotates to allow for helix angle effects; when one tooth shape has been finished, involving typically 100 micron metal removal the gear is indexed to the next tooth space. This method is fairly show but gives high accuracy consistently. Setting up is lengthy because different dressing templates are needed if module, number of teeth, helix angle, or profile correction are changed.The fastest grinding method uses the same principle as hobbing but replaces a gashed and relieved worm by a grinding wheel which is a rack in section. Since high surface speeds are needed the wheel diameter is increased so that wheels of 0.5 m diameter can run at over 2000 rpm to give the necessary 1000 m/min. only single start worms are cut on the wheel but gear rotation speeds are high,100 rpm typically, so it is difficult to design the drive system to give accuracy and rigidity. Accuracy of the process is reasonably high although there is a tendency for wheel and workpiece to deflect variably during grinding so the wheel form may require compensation for machine deflection effects. Generation of a worm shape on the grinding wheel is a slow process since a dressing diamond or roller must not only form the rack profile but has to move axially as the wheel rotates. Once the wheel has been trued, gears can be groundrapidly until redressing is required. This is the most popular method for high production rates with small gear and is usually called the Reishauer method.Large gears are usually generated by the Maag method which is similar to planning in its approach but uses cup grinding wheels of large diameter to form the flanks of the theoretical mating rack. Gears of very large diameter cannot easily be moved so the gear is essentially stationary while the grinding wheel carriage reciprocates in the direction of the helix. The wheel is only in contact over a small part of the facewidth in helical gears so this is not important when only a few gears of this size are made in a year. As with form grinding, after grinding a pair of flanks the gear is indexed to the next pair.A similar method used for medium size gears has stationary wheels, while the rough gear is traversed under the wheels. Corresponding rotational movement of the gear is controlled by steel bands unwrapping from a cylinder of pitch circle diameter so that the motion of gear relative to “rack” is correct.Another method, the Nile approach, uses a wheel which is formed to give the “theoretical mating rack” instead of using two cup wheels as in the Maag method. This approach is best suited to medium precision work on smaller gears and is intermediate in speed between the Reishauer and Maag methods.All grinding processes are slow and costly compared with cutting processed and so are only used when accuracy is essential. A rough rule of thumb is that grinding will increase gear cutting costs by a factor of 10 but the cost of the teeth is often only a small part of the total cost of a gearbox. The accuracies attainable are surprisingly not very dependent on size of gear ; whether a gear is 5 m or 50 m diameter the pitch involute and helix accuracies attainable are of the order of 5 microns or better and more dependent on the skill and patience of the operator and inspectors than on any other factors.It is often assumed that grinding will remove all error generated at the roughing stage. Unfortunately, grinding machines are relatively flexible and so the grinding wheel has a tendency to follow previous errors. The errors will thus be reduced but not completely eliminated unless very many cuts are used; whenever a grinding process is giving in consistent results it is advisable to check the accuracies at the rough-cut stage. The only exception is the form grinding process which will not follow involute errors though it will still allow helix and pitch errors.中文译文齿轮的加工方法加工齿轮轮齿有两种基本的方法：产生过程和形成过程。

附录ToolPurposeUpon completion of this unit, students will be able to:* Rough and explain the difference between finishing.* Choose the appropriate tool for roughing or finishing of special materials and processing.* Recognition Tool Cutting part of the standard elements and perspective.* The right to protect the cutter blade.* List of three most widely used tool material.* Description of each of the most widely used knives made of the material and its processing of Applications.* Space and inclination to understand the definition.* Grinding different tools, plus the principle of space and inclination.* To identify different forms of space and the inclination to choose the application of each form.The main points of knowledge:Rough-finished alloy steel casting materialScattered surplus carbide ceramic materials (junction of the oxide) ToolWith a chip breaking the surface roughness of the D-cutter knives diamondsAfter Kok flank behind the standard point of (former) angle off-chipSide front-side appearance and the outline of the former Kok (I. Kok)Grinding carbon tool steel front-fast finishing horn of rigid steelDouble or multiple-side flank before the dip angle oblique angleSurface-radius Slice root for curlingRough and finishing toolCutting speed only in the surface roughness not required when it is not important. Rough the most important thing is to remove the excess material scattered. Only in surface roughness of the finishing time is important. Unlike rough, finishing the slow processing speed. Chip off with the D-knives, better than the standard point of knives, in Figure 9-10 A, is designed for cutting depth and design, for example, a 5 / 16-inch box cutter blade of the maximum depth of cut 5 / 16 inches, and an 8 mm square block will be cutting knives Corner to 8 mm deep, this tool will be very fast Corner block removal of surplus metal. Slice merits of the deal with that, in a small blade was close thinning. This tool is also a very good finishing tool. But please do not confuse the thin band Tool and Tool-off crumbs. A chip-off is actually counter-productive tool to cut off the chip flakes.And the standard tool of the Corner, compared with chip breaking tool for the Corner is in its on and get grooving, Figure 9-10 B. This tool generally used to block the Corner of rough finishing. While this tool Corner blocks have sufficient strength to carry out deep cut, but the longer the chip will cut off the plane around after shedding a lot of accumulation. Chip is so because the tangles and sharp, and theoperator is a dangerous, so this is a chip from the need to address the problem. Double, or triple the speed of the feed will help to resolve, but this will require greater horsepower and still easily chip very long. Because of the slow processing, however, this action will be a good tool but also because of the small root radius of the processing will be a smooth surface. Especially when processing grey cast iron especially.Cutting Tools appearanceAppearance, sometimes called the contour of the floor plan is where you see the vision or the top down or look at the surface. Figure 9-11 illustrate some of the most common form, those who could be on the cutting tools and grinding out successfully be used. National Standards in its thread-cutting tool on a tiny plane can be as GB thread, the Anglo-American unity and international standards screw threads. A special tool to outline the thread of the plane is to be ground into the correct size.Tools Corner fixedCorner to a number of knives around the 15 degree angle while the other knives and cutting of the straight. When the mill in Figure 9-12 A and 9-12 B, for example by the space and the inclination, these must factor into consideration in the review. Figure 9-12 B Tool Corner block the angle is zero, compared with 9-12 A map is a heavier cutting tools, and the 9-12 A map will take more heat. The same amount of space in front of the two cases are the same.Tool Corner block component and the angleFigure 9-13 Tool Corner block an integral part of the name, and plans 9-14 point of the name, is the machinery industry standards.Grinding Wheel Tool Corner BlockWhen the cutter is fixed in the middle of Dao, Tool Corner block can not be the grinding. Can not do so for the reasons: because of the large number of Dao and extra weight, making Corner together with the grinding is a clumsy and inefficient way. Too much pressure could be added to round on the sand. This can cause the wheel Benglie wheel or because of overheating and the rift on the Corner Tool damage. There are grinding to the possibility of Dao.GrindingA craftsman in his toolbox, should always be a small pocket lining grinding tool. Alumina lining a grinding tool as carbon tool steel and high speed steel tool tool. The silicon carbide lining grinding tool grinding carbide cutting tools. Cutting Tools should always maintain smooth and sharp edge, so that the life expectancy of long knives and processing the surface smooth.Cutting tool materialsCarbon tool steel cutter Corner block usually contains 1.3 percent to 0.9 percent of carbon. These make use of the cutting tool in their tempering temperature higher than about 400 degrees Fahrenheit (205 degrees Celsius) to 500 degrees Fahrenheit (260 degrees Celsius) remained hardness, depending on the content of carbon. These temperature higher than that of carbon tool steel cutter will be changed soft, and it will be the cutting edge. Damaged. Grinding blades or cutting speed faster when using carbon tool steel cutter will be made of the blue, this will be in the imagination. Toolwill be re-hardening and tempering again. So in a modern processing almost no carbon as a tool steel blade.Low-alloy steel cutting tool in the carbon steel tools added tungsten, cobalt, vanadium alloying elements such as the consequences. These elements and the hardness of high-carbon carbide. Increased tool wear resistance. Alloy tool steel that is to say there will be no hard and fast with hot red when the knife's edge can still continue to use it. Low-alloy steel cutting tool is relatively small for a modern processing.High-speed steel with tungsten of 14 percent to 22 percent, or Containing 1.5% to 6% of the W-Mo (molybdenum which accounted for 6 percent to 91 percent). From high-speed steel tool made of a rigid heat, some high-speed steel also contains cobalt, which is formed of rigid factor. Cobalt containing high-speed steel tool can maintain hardness, more than 1,000 degrees Fahrenheit (or 540 degrees Celsius) blade will become soft and easily damaged. After cooling, the tool will harden. When grinding, you must be careful because of overheating and cold at first, so that profile Benglie Zhucheng a variety of metal alloy materials have a special name called Carbide, such as containing tungsten carbide cobalt chrome. In little or iron carbide. However, its high-speed steel cutting speed than the maximum cutting speed is higher 25 percent to 80 percent. Carbide Tool General for cutting force and the intermittent cutting processing, such as processing Chilled Iron.The past, Carbide Tool is mainly used for processing iron, but now carburizing tool for processing all the metal.Carbide Tool into the body than to the high-speed steel tool or casting - lighter alloy cutting tools, because tend to be used as a tool carbide cutting tools. Pure tungsten, carbon carburizing agent or as a dipping formation of the tungsten carbide, suitable for the cast iron, aluminum, non-iron alloy, plastic material and fiber of the machining. Add tantalum, titanium, molybdenum led to the carbon steel The hardness of higher tool, this tool suitable for processing all types of steel. In manufacturing, or tungsten steel alloy containing two or more of a bonding agent and the mixture is hard carbon steel tool, is now generally containing cobalt, cobalt was inquiry into powder and thoroughly mixed, under pressure Formation of Carbide.These cutting tools in the temperature is higher than 1,660 degrees F (870 degrees C) can also be efficiently used. Carbide Tool hardware than high-speed steel tool, used as a tool for better wear resistance. Carbide Tool in a high-speed Gangdao nearly three times the maximum cutting speed of the cutting rate cutting.Made from diamonds to the cutting tool on the surface finish and dimensional accuracy of the high demand and carbide cutting tools can be competitive, but these tools processing the material was more difficult, and difficult to control. Metal, hard rubber and plastic substances can be effective tool together with diamonds and annoyance to the final processing.Ceramic tool (or mixed oxide) is mixed oxide. With 0-30 grade alumina mixture to do, for example, contains about 89 percent to 90 percent of alumina and 10 percent to 11 percent of titanium dioxide. Other ceramic tool is used with the tiny amount of the second oxides Mixed together the cause of pure alumina.Ceramic tools in more than 2,000 degrees F (1095 degrees C) temperature of the work is to maintain strength and hardness. Cutting rates than high-carbon steel knives to 50 percent or even hundreds of percentage. In addition to diamonds and titanium carbide, ceramic tool in the industry is now all the materials of the most hard cutting tool, especially at high temperatures.Tao structure easily broken in a specific situation, broken only carbon intensity of the half to two-thirds. Therefore, in cut, according to the proportion of cutting and milling would normally not be recommended. Ceramics cutting machine breakdown of failure is not usually wear failure, as compared with other materials, their lack of ductility and lower tensile strength.In short, the most widely used by the cutting tool material is cut high-speed steel, low alloy materials and carbide.Gap and dipSpace and inclination of the principle is the most easily to the truck bed lathe tool bladed knives to illustrate. Shape, size of the gap, and dip the type and size will change because of machining. Similarly a grinding tool Corner block is just like brushing your teeth.Gap tool to stop the edge of friction with the workpiece. If there is no gap in Figure 9-15A in the small blades, knives and the side will wear will not be cutting. If there are gaps in Figure 9-15 B, will be a cutting tool. This basic fact apply to any type of tool.Clearance was cutting the size depends on material and the cutting of the material deformation. For example, aluminum is soft and easy to slightly deformed or uplift, when the cutter Corner into space within the perspective and the perspective of the space under, the equivalent in steel mill and will very quickly broken. Table 9-1 (No. 340) that different materials grinding space and perspective.The correct amount of space will be properly protected edge. Too much space will cause the blade vibration (fibrillation), and may edge of total collapse. Tool Corner for the slab block must have a backlash, behind (in front) gap, knife and cut-corner. The main cutting edge is almost as all the cutting work at the cutting edge of the cutting tool on the edge, on the left or right-lateral knives, or cutting tool in the end, cut off on a cutter.Backlash angle for example, the role of a lathe tool Corner to the left block when it mobile. If there is no backlash Kok, Fig 9-16 A, with the only tool will be part of friction rather than cutting. If a suitable backlash Kok, Fig 9-16 B, will be cutting edge and will be well supported. If I have too many gaps, Fig 9-16 C, the edge will not support leading tool vibration (fibrillation) and may be completely broken.Tool gap to the front or rear of the role when it fixed to zero, as shown in Figure 9-17. If not in front of the Gap. Figure 9-17 A, the tool will not only friction and cutting. If a suitable space in front, Fig 9-17 B, but also a good tool will be cutting edge will be well supported. If a big gap in front of Ms, Fig 9-17 C, the tool will lack support, will have a vibrate, and cutting edge may be pressure ulcer.Figure 9-18 illustrate the gap in front of a lathe tool, when it with a 15 degree angle when fixed. The same amount of space on the front fixed to zero, and around thecutter, but the tool is the relatively thin. So the heat away from the blade less. Typically, front-side or front-not too big in Figure 9-19. It is usually from zero degrees to 20 degrees change, an average of about 15 degrees. There are clear advantages, according to the following: good cutting angle so that the cutting edge of the work was well, but relatively thin chips. Cutting Tools is the weakest part. By the former angle, the blade In the form of points around the workpiece. Cutting Edge shock will cause the entire tool vibration. When cutting the work nearly completed, the final section of metal was to ring, packing iron sheet or tangles in the form of the metal ball away gradually replaced by direct removal. Pressure tends to stay away from the workpiece cutting tool rather than narrow the gap between its parts. 9-19 A in the plan was an example of the use of a 30-degree lateral Cutting Angle tool processing thin slice example. A mathematical proof of the plan 9-19 B in the right-angle triangle trip is to expand the use of a map 9-19 A right triangle in the same way, that is, in the direction of upward mobility to feed a 0.010 inch. Right triangle adjacent to the edge (b) and feed 0.010 feet equivalent.The following formula using triangulation to explain:Kok cosine A = right-angle-B / C XiebianOr cosine of 30 degrees = b / c0.886 = b/0.010b = 0.866 * 0.010b = 0.00866 (bladed too thin)When the mobile tool, the purpose of front-to be processed to eliminate from the surface of the cut-cutting tools. This angle is usually from 8 degrees to 15 degrees, but in exceptional circumstances it as much as 20 degrees to 30 degrees. If there is no gap in Figure 9-20 A, cutting tools will be tied up, sharp beep, and the rivets may be the first to die away. The appropriate space, in Figure 9-20 B, cutting tool will be cutting well.A manufacturing plant or cut off the fast-cutter blade with three space, in a root-surface or surface and the other in bilateral level, in Figure 9-21. If a tool Corner block from the date of the face, It can have up to five space, in Figure 9-22. Grooving tool sometimes known as area reduction tool used to cut a groove in the shallow end of the thread.Inclination is the top tool inclination or, in the Tool Corner block on the surface. Changes depending on the angle of the cutting material. Improvement of the cutting angle, the blade shape, and guidelines from the chip from the edge of the direction. Chip dip under the direction named. For example, if a chip from the edge cutter outflow, it is called anterior horn. If the chip to the back of the outflow, that is, to the Dao, which is known as the horn. Some mechanical error and the staff horn as a front-or knife corner.Single tool like Tool Corner block may be the only edge of the blade side oblique angle, or in the back, only to end on the edge of the horn, or they may have roots in the face or front surface of the main Cutting edge of the blade and cutting edge of the horn and a roll angle of the portfolio. In the latter case, cut off most of the surface with a cutter and a chip to the point of view in the tool horn and roll angle in bothdirections has been moved out.Two different roll angle in Figure 9-23 A and 9-23 B was an example. Angle depends on the size and type of material was processed.9-24 A map in Figure 9-24 B and gives examples of zero to a fixed cutter after the two different angle. In Figure 9-25 B and 9-25 A Tool to the regular 15-degree angle. Figure 9-26 tool to display a 15 degree angle fixed, but in this case a tool to roll angle after angle and the combination of form close to the workpiece. Double or multiple chips to lead the inclination angle of a mobile or two away from the edge of the back and side to stay away from the cutter.Comparison of various horn, shown in Figure 9-27, Corner of the horn of a negative point of view, and zero is the point of view. These dip in the Corner cutter on the manifestation of a decision in the hands of the processing needs of the pieces. After Kok was the size of the type of materials processing, and knives in Dao fixed on the way.The type of lateral oblique angleFigure 9-28 examples of tools Corner blocks and four different types of lateral oblique angle of the cross-sectional. Figure 9-28 A, is zero lateral oblique angle, like some of the brass materials, some bronze and some brittle plastic material is particularly necessary. Standard side oblique angle, in Figure 9-28 B, is the most common one of the bevel side. In the ductile material on the deep cut, easy to chip in the tool around the accumulation of many, and this will cause danger to the operator. The chip will become a deal with the problem. Such a tool to cut off the grey cast iron is the most appropriate.Chip laps volumes, Figure 9-28 C, is one of the best types of inclination, especially in the ductile material on the special deep cutting. Chip small crimp in close formation against the Dao of bladed knives against the will of the rupture. The chip rolled up to maintain a narrow trough of the chip will guarantee that the width of closely Lane V ol. The chip is very easy to handle. V olume circle with a chip is not a cut-chip.Chip cut off, in Figure 9-28 D, leading to chip in the corner was cut off, and then to small chips fell after the chip. The need to cut off a chip provides up to 25 percent of the force. This inclination of the stickiness of the steel is good.Gap KokWhen cutting any material time, the gap should always be the smallest size, but the gap should never angle than the required minimum angle small space. The gap is too small knives Kok will lead to friction with the workpiece. Choice of space at the corner to observe the following points:1. When processing hardness, stickiness of the material, the use of high-speed steel tool cutting angle should be in the space of 6 to 8 degrees, and the use of carbon tool steel cutter at the corner of the gap in size should be 5 degrees to 7 degrees.2. When the processing of carbon steel, low carbon steel, cast iron when the gap angle should be the size of high-speed steel tool 8 degrees to 12 degrees, and carbon tool steel cutter 5 degrees to 10 degrees.3. Scalability when processing materials such as copper, brass, bronze, aluminum,iron, etc. Zhanxing materials, space Kok should be the size of high-speed steel tool 12 degrees to 16 degrees, carbon steel knives 8 degrees to 14 , Mainly because of the plastic deformation of these metals. This means that, when the cutter and around them, the soft metal to some minor deformation or protruding, and this tool will be friction. At this time, we must have a tool on the additional space.刀具目的在完成这一个单元之后，学生将会能够:* 解释粗加工和精加工之间的差别。

本科毕业设计（论文）外文资料翻译外文翻译英文原文High-speed machining and demand for the development of High-speed machining is contemporary advanced manufacturing technology an important component of the high-efficiency, High-precision and high surface quality, and other features. This article presents the technical definition of the current state of development of China's application fields and the demand situation.High-speed machining is oriented to the 21st century a new high-tech, high-efficiency, High-precision and high surface quality as a basic feature, in the automobile industry, aerospace, Die Manufacturing and instrumentation industries gained increasingly widespread application, and has made significant technical and economic benefits. contemporary advanced manufacturing technology an important component part.HSC is to achieve high efficiency of the core technology manufacturers, intensive processes and equipment packaged so that it has a high production efficiency. It can be said that the high-speed machining is an increase in the quantity of equipment significantly improve processing efficiency essential to the technology. High-speed machining is the major advantages : improve production efficiency, improve accuracy and reduce the processing of cutting resistance.The high-speed machining of meaning, at present there is no uniform understanding, there are generally several points as follows : high cutting speed. usually faster than that of their normal cutting 5 -10 times; machine tool spindle speed high, generally spindle speed in -20000r/min above 10,000 for high-speed cutting; Feed at high velocity, usually 15 -50m/min up to 90m/min; For different cutting materials and the wiring used the tool material, high-speed cutting the meaning is not necessarily the same; Cutting process, bladed through frequency (Tooth Passing Frequency) closer to the "machine-tool - Workpiece "system the dominant natural frequency (Dominant Natural Frequency), can be considered to be high-speed cutting. Visibility high-speed machining is a comprehensive concept.1992. Germany, the Darmstadt University of Technology, Professor H. Schulz in the 52th on the increase of high-speed cutting for the concept and the scope, as shown in Figure 1. Think different cutting targets, shown in the figure of the transition area (Transition), to be what is commonly called the high-speed cutting, This is also the timeof metal cutting process related to the technical staff are looking forward to, or is expected to achieve the cutting speed.High-speed machining of machine tools, knives and cutting process, and other aspects specific requirements. Several were from the following aspects : high-speed machining technology development status and trends.At this stage, in order to achieve high-speed machining, general wiring with high flexibility of high-speed CNC machine tools, machining centers, By using a dedicated high-speed milling, drilling. These equipment in common is : We must also have high-speed and high-speed spindle system feeding system, Cutting can be achieved in high-speed process. High-speed cutting with the traditional cutting the biggest difference is that "Machine-tool-workpiece" the dynamic characteristics of cutting performance is stronger influence. In the system, the machine spindle stiffness, grip or form, a long knife set, spindle Broach, torque tool set, Performance high-speed impact are important factors.In the high-speed cutting, material removal rate (Metal Removal Rate, MRR), unit time that the material was removed volume, usually based on the "machine-tool-workpiece" whether Processing System "chatter." Therefore, in order to satisfy the high-speed machining needs, we must first improve the static and dynamic stiffness of machine spindle is particularly the stiffness characteristics. HSC reason at this stage to be successful, a very crucial factor is the dynamic characteristics of the master and processing capability.In order to better describe the machine spindle stiffness characteristics of the project presented new dimensionless parameter - DN value, used for the evaluation of the machine tool spindle structure on the high-speed machining of adaptability. DN value of the so-called "axis diameter per minute speed with the product." The newly developed spindle machining center DN values have been great over one million. To reduce the weight bearing, but also with an array of steel products than to the much more light ceramic ball bearings; Bearing Lubrication most impressive manner mixed with oil lubrication methods. In the field of high-speed machining. have air bearings and the development of magnetic bearings and magnetic bearings and air bearings combined constitute the magnetic gas / air mixing spindle.Feed the machine sector, high-speed machining used in the feed drive is usually larger lead, multiple high-speed ball screw and ball array of small-diameter silicon nitride (Si3N4) ceramic ball, to reduce its centrifugal and gyroscopic torque; By usinghollow-cooling technology to reduce operating at high speed ball screw as temperature generated by the friction between the lead screw and thermal deformation.In recent years, the use of linear motor-driven high-speed system of up to'' Such feed system has removed the motor from workstations to Slide in the middle of all mechanical transmission links, Implementation of Machine Tool Feed System of zero transmission. Because no linear motor rotating components, from the role of centrifugal force, can greatly increase the feed rate. Linear Motor Another major advantage of the trip is unrestricted. The linear motor is a very time for a continuous machine shop in possession of the bed. Resurfacing of the very meeting where a very early stage movement can go, but the whole system of up to the stiffness without any influence. By using high-speed screw, or linear motor can greatly enhance machine system of up to the rapid response. The maximum acceleration linear motors up to 2-10G (G for the acceleration of gravity), the largest feed rate of up to 60 -200m/min or higher.2002 world-renowned Shanghai Pudong maglev train project of maglev track steel processing, Using the Shenyang Machine Tool Group Holdings Limited McNair friendship company production plants into extra-long high-speed system for large-scale processing centers achieve . The machine feeding system for the linear guide and rack gear drive, the largest table feed rate of 60 m / min, Quick trip of 100 m / min, 2 g acceleration, maximum speed spindle 20000 r / min, the main motor power 80 kW. X-axis distance of up to 30 m, 25 m cutting long maglev track steel error is less than 0.15 mm. Maglev trains for the smooth completion of the project provided a strong guarantee for technologyIn addition, the campaign machine performance will also directly affect the processing efficiency and accuracy of processing. Mold and the free surface of high-speed machining, the main wiring with small cut deep into methods for processing. Machine requirements in the feed rate conditions, should have high-precision positioning functions and high-precision interpolation function, especially high-precision arc interpolation. Arc processing is to adopt legislation or thread milling cutter mold or machining parts, the essential processing methods.Cutting Tools Tool Material developmenthigh-speed cutting and technological development of the history, tool material is continuous progress of history. The representation of high-speed cutting tool material is cubic boron nitride (CBN). Face Milling Cutter use of CBN, its cutting speed can be as high as 5000 m / min, mainly for the gray cast iron machining. Polycrystalline diamond(PCD) has been described as a tool of the 21st century tool, It is particularly applicable to the cutting aluminum alloy containing silica material, which is light weight metal materials, high strength, widely used in the automobile, motorcycle engine, electronic devices shell, the base, and so on. At present, the use of polycrystalline diamond cutter Face Milling alloy, 5000m/min the cutting speed has reached a practical level. In addition ceramic tool also applies to gray iron of high-speed machining;Tool Coating : CBN and diamond cutter, despite good high-speed performance, but the cost is relatively high. Using the coating technology to make cutting tool is the low price, with excellent mechanical properties, which can effectively reduce the cost. Now high-speed processing of milling cutter, with most of the wiring between the Ti-A1-N composite technology for the way of multi-processing, If present in the non-ferrous metal or alloy material dry cutting, DLC (Diamond Like Carbon) coating on the cutter was of great concern. It is expected that the market outlook is very significant;Tool clamping system : Tool clamping system to support high-speed cutting is an important technology, Currently the most widely used is a two-faced tool clamping system. Has been formally invested as a commodity market at the same clamping tool system are : HSK, KM, Bigplus. NC5, AHO systems.In the high-speed machining, tool and fixture rotary performance of the balance not only affects the precision machining and tool life. it will also affect the life of machine tools. So, the choice of tool system, it should be a balanced selection of good products.Process ParametersCutting speed of high-speed processing of conventional shear velocity of about 10 times. For every tooth cutter feed rate remained basically unchanged, to guarantee parts machining precision, surface quality and durability of the tool, Feed volume will also be a corresponding increase about 10 times, reaching 60 m / min, Some even as high as 120 m / min. Therefore, high-speed machining is usually preclude the use of high-speed, feed and depth of cut small cutting parameters. Due to the high-speed machining cutting cushion tend to be small, the formation of very thin chip light, Cutting put the heat away quickly; If the wiring using a new thermal stability better tool materials and coatings, Using the dry cutting process for high-speed machining is the ideal technology program.High-speed machining field of applicationFlexible efficient production lineTo adapt to the needs of new models, auto body panel molds and resin-prevention block the forming die. must shorten the production cycle and reduce the cost ofproduction and, therefore, we must make great efforts to promote the production of high-speed die in the process. SAIC affiliated with the company that : Compared to the past, finishing, further precision; the same time, the surface roughness must be met, the bending of precision, this should be subject to appropriate intensive manual processing. Due to the extremely high cutting speed, and the last finishing processes, the processing cycle should be greatly reduced.To play for machining centers and boring and milling machining center category represented by the high-speed machining technology and automatic tool change function of distinctions Potential to improve processing efficiency, the processing of complex parts used to be concentrated as much as possible the wiring process, that is a fixture in achieving multiple processes centralized processing and dilute the traditional cars, milling, boring, Thread processing different cutting the limits of technology, equipment and give full play to the high-speed cutting tool function, NC is currently raising machine efficiency and speed up product development in an effective way. Therefore, the proposed multi-purpose tool of the new requirements call for a tool to complete different parts of the machining processes, ATC reduce the number of ATC to save time, to reduce the quantity and tool inventory, and management to reduce production costs. More commonly used in a multifunctional Tool, milling, boring and milling, drilling milling, drilling-milling thread-range tool. At the same time, mass production line, against the use of technology requires the development of special tools, tool or a smart composite tool, improve processing efficiency and accuracy and reduced investment. In the high-speed cutting conditions, and some special tools can be part of the processing time to the original 1 / 10 below, results are quite remarkable.HSC has a lot of advantages such as : a large number of materials required resection of the workpiece with ultrafine, thin structure of the workpiece, Traditionally, the need to spend very long hours for processing mobile workpiece and the design of rapid change, short product life cycle of the workpiece, able to demonstrate high-speed cutting brought advantages.中文译文高速切削加工的发展及需求高速切削加工是当代先进制造技术的重要组成部分，拥有高效率、高精度及高表面质量等特征。

TOOL WEAR MECHANISMS ON THE FLANK SURFACE OF CUTTINGINSERTSFOR HIGH SPEED WET MACHINING5.1 IntroductionAlmost every type of machining such as turning, milling, drilling, grinding..., uses a cutting fluid to assist in the cost effective production of pa rts as set up standard required by the producer [1]. Using coolant with some cutting tools material causes severe failure due to the lack of their resistance to thermal shock (like AL2O3 ceramics), used to turn steel. Other cutting tools materials like cubic boron nitride (CBN) can be used without coolant, due to the type of their function. The aim of using CBN is to raise the temperature of the workpice to high so it locally softens and can be easily machined.The reasons behind using cutting fluids can be summarized as follows.® Extending the cutting tool life achieved by reducing heat generated and as a result less wear rate is achieved. It will also eliminate the heat from theshear zone and the formed chips.® Cooling the work piece of high quality materia l under operation plays an important role since thermal distortion of the surface and subsurfacedamage is a result of excessive heat that must be eliminated or largelyreduced to produce a high quality product.Reducing cutting forces by its lubricating e ffect at the contact interface region and washing and cleaning the cutting region during machining from small chips. The two main reasons for using cutting fluids are cooling and lubrication.Cutting Fluid as a Coolant:The fluid characteristics and condition of use determine the coolant action of the cutting fluid, which improves the heat transfer at the shear zone between the cutting edge, work piece, and cutting fluid. The properties of the coolant in this case must include a high heat capacity to carry away heat and good thermal conductivity to absorb the heat from the cutting region. The water-based coolant emulsion with its excellent high heat capacity is able to reduce tool wear [44]. Cutting Fluid as a Lubricant:The purpose is to reduce friction bet ween the cutting edge, rake face and the work piece material or reducing the cutting forces (tangential component). As the friction drops the heat generated isdropped. As a result, the cutting tool wear rate is reduced and the surface finish is improved.Cutting Fluid PropertiesFree of perceivable odorPreserve clarity throughout lifeKind and unirritated to skin and eyes.Corrosion protection to the machine parts and work piece.Cost effective in terms off tool life, safety, dilution ratio, and fluid lif e.[1]5.1.1 Cutting Fluid TypesThere are two major categories of cutting fluidsNeat Cutting OilsNeat cutting oils are poor in their coolant characteristics but have an excellent lubricity. They are applied by flooding the work area by a pump and re-circulated through a filter, tank and nozzles. This type is not diluted by water, and may contain lubricity and extreme-pressure additives to enhance their cutting performance properties. The usage of this type has been declining for their poor cooling ability, causing fire risk, proven to cause health and safety risk to the operator [1].® Water Based or Water Soluble Cutting FluidsThis group is subdivided into three categories:1.Emulsion ` mineral soluble' white-milky color as a result of emulsion of oil inwater. Contain from 40%-80% mineral oil and an emulsifying agent beside corrosion inhibitors, beside biocide to inhibit the bacteria growth.2.Micro emulsion `semi-synthetic' invented in 1980's, has less oil concentrationand/or higher emulsifier ratio 10%-40% oil. Due to the high levels ofemulsifier the oil droplet size in the fluid are smaller which make the fluid more translucent and easy to see the work piece during operation. Otherimportant benefit is in its ability to emulsify any leakage of oil from themachine parts in the cutting fluid, a corrosion inhibitors, and bacteria control.3.Mineral oil free `synthetic' is a mix of chemicals, water, bacteria control,corrosion inhibitors, and dyes. Does not contain any mineral oils, andprovides good visibility.23 to the work piece. bare in mind that the lack of mineral oil in this type of cuttingfluid needs to take more attention to machine parts lubrication since it should not leave an oily film on the machine parts, and might cause seals degradation due the lack of protection.5.1.2 Cutting Fluid SelectionMany factors influence the selection of cutting fluid; mainly work piece material, type of machining operation, machine tool parts, paints, and seals. Table 5-1 prepared at the machine tool industry res earch association [2] provides suggestions on the type of fluid to be used.5.1.3 Coolant ManagementTo achieve a high level of cutting fluids performance and costeffectiveness, a coolant recycling system should be installed in the factory. This system will reduce the amount of new purchased coolant concentrate and coolant disposable, which will reduce manufacturing cost. It either done by the company itself or be rented out, depends on the budget and management policy of the company [1].Table 5-1 Guide to the selection of cutting fluids for general workshop applications.Machining operation Workpiece materialFree machining and low - carbon Medium- Carbon steels High Carbon and alloy steels Stainlessand heattreated GrindingClear type soluble oil, semi synthetic or chemical Turning General purpose, soluble oil, semi synthetic or synthetic fluid Extreme-pressuresoluble oil,semi-synthetic orsyntheticfluid Milling General purpose, soluble oil, semi synthetic or synthetic Extreme- pressure soluble oil, semi- synthetic or synthetic Extreme-pressuresoluble oil,semi-synthetic orsyntheticfluid(neat cutting oilsmay beDrillingExtreme- pressure soluble oil, semi- synthetic or GearShapping Extreme-pressure soluble oil, Neat-cutting oils preferable HobbingExtreme-pressure soluble oil, semi-synthetic or synthetic fluid (neat cutting oils may be Neat-cutti ng oils BratchingExtreme-pressure soluble oil, semi-synthetic or synthetic fluid (neat Tapping Extreme-pressure soluble oil, semi-synthetic or Neat-cuttingpreferableNote: some entreis deliberately extend over two or more columns, indicating awide range of possible applications. Other entries are confined to aspecific class of work material.Adopt ed f rom Edw ard and Wri ght [2]5.2 Wear Mechanisms Under Wet High Speed M achiningIt is a common belief that coolant usage in metal cutting reduces cuttingtemperature and extends tools life. However, this researchshowed that this is not necessarily true to be generalized overcutting inserts materials. Similar research was ca rried out ondifferent cutting inserts materials and cutting conditionssupporting our results. Gu et al [36] have recorded adifference in tool wear mechanisms between dry and wetcutting of C5 milling inserts. Tonshoff et al [44] alsoexhibited different wear mechanisms on AL 2O 3/TiC inserts inmachining ASTM 5115, when using coolants emulsionscompared to dry cutting. In addition, Avila and Abrao [20]experienced difference in wear mechanisms activated at theflank side, when using different coolants in t estingAL 2O 3lTiC tools in machining AISI4340 steel. The wearmechanisms and the behavior of the cutting inserts studied inthis research under wet high speed-machining (WHSM)condition is not fully understood. Therefore, it was theattempt of this research to focus on the contributions incoating development and coating techniques of newlydeveloped materials in order to upgrade their performance attough machining conditions. This valuable research providesinsight into production timesavings and increase inprofitability. Cost reductions are essential in the competitiveglobal economy; thus protecting local markets and consistingin the search of new ones.5.3 Experimental Observations on Wear Mechanisms of Un-CoatedCemented Carbide Cutting Inserts in High Speed WetMachiningIn this section, the observed wear mechanisms are presented of uncoated cemented carbide tool (KC313) in machining ASTM 4140 steel under wet condition. The overall performance of cemented carbide under using emulsion coolant has been improved in terms of extending tool life and reducing machining cost. Different types of wear mechanisms were activated at flank side of cutting inserts as a result of using coolant emulsion during machining processes. This was due to the effect of coolant in reducing the average temperature of the cutting tool edge and shear zone during machining. As a result abrasive wear was reduced leading longer tool life. The materials of cutting tools behave differently to coolant because of their varied resistance to thermal shock. The following observations recorded the behavior of cemented carbide during high speed machining under wet cutting.Figure5-1 shows the flank side of cutting inserts used at a cutting speed of 180m/min. The SEM images were recorded after 7 minutes of machining. It shows micro-abrasion wear, which identified by the narrow grooves along the flank side in the direction of metal flow, supported with similar observations documented by Barnes and Pashby [41] in testing through-coolant-drilling inserts of aluminum/SiC metal matrix composite. Since the cutting edge is the weakest part of the cutting insert geometry, edge fracture started first due to the early non-smooth engagement between the tool and the work piece material. Also, this is due to stress concentrations that might lead to a cohesive failure on the transient filleted flank cutting wedge region [51, 52]. The same image of micro-adhesion wear can be seen at the side and tool indicated by the half cone27 shape on the side of cutting tool. To investigate further, a zoom in view was taken atthe flank side with a magnification of 1000 times and presented in Figure 5-2A. It shows clear micro-abrasion wear aligned in the direction of metal flow, where the cobalt binder was worn first in a hi gher wear rate than WC grains which protruded as big spherical droplets. Figure 5-2B provides a zoom-in view that was taken at another location for the same flank side. Thermal pitting revealed by black spots in different depths and micro-cracks, propagated in multi directions as a result of using coolant. Therefore, theii~ial pitting, micro-adhesion and low levels of micro-abrasion activated under wet cutting; while high levels of micro-abrasion wear is activated under dry cutting (as presented in the prev ious Chapter).Figure 5-3A was taken for a cutting insert machined at 150mlmin. It shows a typical micro-adhesion wear, where quantities of chip metal were adhered at the flank side temporarily. Kopac [53] exhibited similar finding when testing HSS-TiN drill inserts in drilling SAE1045 steel. This adhered metal would later be plucked away taking grains of WC and binder from cutting inserts material and the process continues. In order to explore other types of wear that might exist, a zoom-in view with magnification of 750 times was taken as shown in Figure5-3B. Figure 5-3B show two forms of wears; firstly, micro-thermal cracks indicated by perpendicular cracks located at the right side of the picture, and supported with similar findings of Deamley and Trent [27]. Secondly, micro-abrasion wear at the left side of the image where the WC grains are to be plucked away after the cobalt binder was severely destroyed by micro-abrasion. Cobalt binders are small grains and WC is the big size grains. The severe distort ion of the binder along with the WC grains might be due to the activation of micro-adhesion and micro-abrasionFigure 5-1 SEM image of (KC313) showing micro abrasion and micro-adhesion (wet).SEM micrographs of (KC313) at 180m/min showing micro-abrasion where cobalt binder was worn first leaving protruded WC spherical droplets (wet).(a)SEM micrographs of (KC313) at 180m/min showing thermal pitting (wet).Figure 5-2 Magnified views of (KC313) under wet cutting: (a) SEM micrographs of (KC313) at 180mlmin showing micro-abrasion where cobalt binderwas worn first leaving protruded WC spherical droplets (wet ), (b) SEMmicrographs of (KC313) at 180.m/min showing thermal pitting (wet ).SEM image showing micro-adhesion wear mechanism under 150m/min (wet).(a)SEM image showing micro-thermal cracks, and micro-abrasion.Figure 5-3 Magnified views of (KC313) at 150m/min (wet): (a) SEM image showing micro-adhesion wear mechanism under 150m/min (wet), (b) SEM image showing micro-fatigue cracks, and micro-abrasion (wet).Wear at the time of cutting conditions of speed and coolant introduction. Therefore, micro-fatigue, micro-abrasion, and micro-adhesion wear mechanisms are activated under wet condition, while high levels of micro-abrasion were observed under dry one.Next, Figure 5-4A was taken at the next lower speed (120m/min). It shows build up edge (BUE) that has sustained its existence throughout the life of the cutting tool, similar to Huang [13], Gu et al [36] and Venkatsh et al [55]. This BUE has protected the tool edge and extended its life. Under dry cutting BUE has appeared at lower speeds (90 and 60 m/min), but when introducing coolant BUE started to develop at higher speeds, This is due to the drop in shear zone temperature that affected the chip metal fl ow over the cutting tool edge, by reducing the ductility to a level higher than the one existing at dry condition cutting. As a result, chip metal starts accumulating easier at the interface between metal chip flow, cutting tool edge and crater surface to form a BUE. In addition to BUE formation, micro-abrasion wear was activated at this speed indicated by narrow grooves.To explore the possibility of other wear mechanisms a zoom-in view with a magnification of 3500 times was taken and shown in Figure 5-4B. Micro- fatigue is evident by propagated cracks in the image similar to Deamley and Trent [27] finding. Furthermore, Figure 5-4B shows indications of micro-abrasion wear, revealed by the abrasion of cobalt binder and the remains of big protruded WC grains. However, the micro-abrasion appeared at this speed of 120m/min is less severe than the same type of micro-wear observed at 150m/min speed, supported with Barnes [41] similar findings. Therefore, micro-abrasion, BUE and micro-fatigue were activated under wet condition while, adhesion, high levels micro-abrasion, and no BUE were under dry cutting.SEM i m a g e o f(KC313) showing build up e d g e under 120m/min (wet).(a)SEM i m a g e o f(KC3 13) showing micro-fatigue, and micro-abrasion (wet). Figure 5-4 SEM images of (KC313) at 120m/min (wet), (a) SEM image of (KC313). showing build up edge, (b) SEM image of(K C313) showing micro-fatigue and micro-abrasion33 Figure 5-5 is for a cutting tool machined at 90m/min, that presents a goodcapture of one stage of tool life after the BUE has been plucked away. The bottom part of the flank side shows massive metal adhesion from the work piece material. The upper part of the figure at the edge shows edge fracture. To stand over the reason of edge fracture, the zoom-in view with magnification of 2000 times is presented in Figure 5-6A. The micro-fatigue crack image can be seen as well as micro-attrition revealed by numerous holes, and supported with Lim et al [31] observations on HSS-TiN inserts. As a result of BUE fracture from the cutting tool edge, small quantities from the cutting tool material is plucked away leaving behind numerous holes. Figure 5-6B is another zoom-in view of the upper part of flank side with a magnification of 1000 times and shows micro-abrasion wear indicated by the narrow grooves. Furthermore, the exact type of micro-wear mechanism appeared at the flank side under 60 m/min. Therefore, in comparison with dry cutting at the cutting speed of 90 m/min and 60 m/min, less micro-abrasion, bigger BUE formation, and higher micro-attrition rate were activated.Figure 5-5 SEM image showing tool edge after buildup edge was plucked away.SEM image showing micro-fatigue crack, and micro-attrition.(a)SEM image showing micro-abrasion.Figure 5-6 SEM images of (KC313) at 90m/min:(a) SEM image showing micro-fatigue crack, and micro-attrition, (b) SEM image showingmicro-abrasion.5.4 Experimental Observations on Wear Mechanisms of Coated CementedCarbide with TiN-TiCN-TiN Coating in High Speed WetMachiningInvestigating the wear mechanisms of sandwich coating under wet cutting is presented in this section starting from early stages of wear. Figure 5-7 shows early tool wear starting at the cutting edge when cutting at 410m/min. Edge fracture can be seen, it has started at cutting edge due to non-smooth contact between tool, work piece, micro-abrasion and stress concentrations. To investigate further the other possible reasons behind edge fracture that leads to coating spalling, a zoom-in view with magnification of 2000 ti mes was taken and presented at Figure 5-8A. Coating fracture can be seen where fragments of TiN (upper coating) had been plucked away by metal chips. This took place as result of micro-abrasion that led to coating spalling. On the other hand, the edge is t he weakest part of the cutting insert geometry and works as a stress concentrator might lead to a cohesive failure on the transient filleted flank cutting wedge region [51, 52].Both abrasion wear and stress concentration factor leave a non-uniform edge configuration at the micro scale after machining starts. Later small metal fragments started to adhere at the developed gaps to be later plucked away by the continuous chip movement as shown in Figure 5-8A. Another view of edge fracture was taken of the same cutting tool with a magnification of 2000 times as shown in Figure 5-8B. It presents fracture and crack at the honed tool edge. A schematic figure indicated by Figure 5-9, presented the progressive coated cutting inserts failure starting at the insert edge. It was also noticed during the inserts test that failure takes place first at the inserts edge then progressed toward the flank side. Consequently, a study on optimizing the cutting edgeFigure 5-7 SEM image of (KC732) at 410m/min showing edge fractur e and micro-abrasion (wet).SEM image showing edge fracture.(a)SEM image showing fracture and crack at the honed insert edge.Figure 5-8 SEM of (KC732) at 410m/min and early wear stage (wet): (a) SEM image showing edge fracture, (b) SEM image showing fr acture and crack atthe honed insert edge.radius to improve coating adhesion, and its wear resistance, might be also a topic for future work.Figure 5-1.0A was taken after tool failure at a speed of 410m/min. It shows completely exposed substrate and severe sliding wear at the flank side. The coating exists at the crater surface and faces less wear than the flank side. Therefore it works as an upper protector for the cutting edge and most of the wear will take place at the flank side as sliding wear. Figu re 5-10B is a zoom-in view with magnification of 3500 times, and shows coating remaining at the flank side. Nonetheless, micro-abrasion and a slight tensile fracture in the direction of metalchip flow. Ezugwa et al [28] and Kato [32] have exhibited simila r finding. However, the tensile fracture in this case is less in severity than what had been observed at dry cutting. This is due to the contribution of coolant in dropping the cutting temperature, which has reduced the plastic deformation at high temperature as a result. Hence, in comparison with the dry cutting at the same speed, tensile fracture was available with less severity and micro-abrasion/sliding. However, in dry cutting high levels of micro-abrasion, high levels of tensile fracture and sliding wear occurred.Figure 5-11 was taken at early stages of wear at a speed of 360m/min. It shows sliding wear, coating spalling and a crack starting to develop between TiN and TiCN coating at honed tool edge. Figure5-12A shows nice presentation of what had been described earlier regarding the development of small fragments on the tool edge. The adhered metal fragments work along with micro-abrasion wear to cause coating spalling.SEM image showing sliding wear.(a)SEM image showing micro-abrasion and tensile fracture.Figure 5-10 SEM images of (KC732) at 410m/min after failure (wet): (a) SEM image showing sliding wear, (b) SEM image showing micro-abrasionand tensile fracture.Figure 5-11 SEM image at early stage of wear of 360m/min (wet) showing coating and spalling developing crack between TiN and TiCN layers.The size of the metal chip adhered at the edge is almost 15g. Since it is unstable it will be later plucked away taking some fragments of coatings with it and the process continues. Another zoom in view with a magnification of 5000 times for the same insert is shown in Figure 5-12B indicating a newly developed crack between the coating layers.Figure 5-13A is taken of the same insert after failure when machining at 360m/min and wet condition. Coating spalling, and sliding wear can be seen and indicated by narrow grooves. In addition, initial development of notch wear can be seen at the maximum depth of cut.Further investigation is carried out by taking a zoom in view with a magnification of 2000 times as shown in Figure 5-13B. A clear micro-abrasion wear and micro-fatigue cracks were developed as shown, which extended deeply through out the entire three coating layers deep until the substrate. Therefore, in comparison with dry cutting, micro-fatigue crack, less tensile fracture, less micro-abrasion wear were activated at wet cutting. While micro- fatigue crack, high levels of micro-abrasion, and high levels of tensile fracture are distinguish the type of wear under dry condition at the same cutting spee d.Next, Figure 5-14A is taken for cutting tools machined at 310m/min. The results are similar to the previous inserts machined at 360m/min, where adhesion of metal fragments occurred at the tool edge, sliding wear and coating spalling. In addition, the black spot appeared at the top of the figure on the crater surface is a void resulting from imperfections in the coating process. At this condition, the crater surface will be worn faster than the flank surface.SEM image showing adhered metal fragments at tool edge.(a)SEM image showing developed crack between coating layers.Figure 5-12 SEM image of (KC732) at early wear 360m/min (wet): (a) SEM image showing adhered metal fragments at tool edge, (b) SEM image showingdeveloped crack between coating layers.(a)SEM image showing coating spalling and sliding wear after tool failure(b)SEM image showing micro-abrasion, and micro-fatigue cracks developedbetween coating layersFigure 5-13 SEM image of KC732 after failure machined at 360m/min(b)(wet): (a) SEM image showing coating spalling and sliding wear after toolfailure, (b) SEM image showing micro-abrasion, and micro-fatiguecracks developed between coating layers.翻译：在高速潮湿机械加工条件下后刀面表层磨损机理5.1 介绍几乎每类型用机器制造譬如转动, 碾碎, 钻井, 研..., 使用切口流体协助零件的有效的生产当设定标准由生产商[ 1 ] 需要。

机械加工外文翻译、中英文翻译、机械类外文文献翻译The engine lathe is an old but still useful metal removal machine with many desirable attributes。

While it is no longer commonlyXXX。

In today's n shops。

it has largely been XXX。

turret lathes。

and automatic XXX of single-point tooling for maximum metal removal。

and the use of form tools for finished products that are on par with the fastest processing XXX.When it XXX for the engine lathe。

it largely depends on the skill of the operator。

Design XXX part for n。

it is XXX.XXX cutting tools。

XXX ns。

as the machine can perform these ns in one setup。

They are also capable of producing parts with high n and accuracy。

XXX industries.Now more than ever。

n machining XXX of a specific method。

the XXX.When designing for low quantities。

such as 100 or 200 parts。

it is most cost-effective to use a XXX。

designers should aim to minimize the number of ns required.Another n for n XXX。

Machining Techniques And Too l Drilling and DrillsDrilling involves producing through or blind holes in a workpiece by forcing a tool, which rotates around its axis, against the workpiece.Consequently, the range of cutting from that axis of rotation is equal to the radius of the required hole. In practice, two symmetrical cutting edges that rotate about the same axis are employed.Drilling operations can be carried out by using either hand drills or drilling machines. The latter differ in size and construction. Nevertheless, the tool always rotates around its axis while the workpiece is kept firmly fixed. This is contrary to drilling on a lathe.Cutting Tool for Drilling OperationIn drilling operations, a cylindrical rotary-end cutting tool, called a drill, is employed. The drill can have either one or more cutting edges and corresponding flutes, which can be straight or helical.The function of the flutes is to provide outlet passages for the chips generated during the drilling operation and also to allow lubricants and coolants to reach the cutting edges and the surface being machined. Following is a survey of the commonly used drills.Twist drill. The twist drill is the most common type of drill. It has two cutting edges and two helical flutes that continue over the length of the drill body,. The drill also consists of a neck and a shank that can be either straight or tapered.In the latter case, the shank is fitted by the wedge action into the tapered socket of the spindle and has a tang, which goes into a slot in the spindle socket, thus acting as a solid means for transmitting rotation.On the other hand, straight-shank drills are held in a drill chuck that is, in turn, fitted into the spindle socket in the same way as tapered shank drills.The two cutting edges are referred to as the lips, and are connected together by a wedge, which is a chisel-like edge. The twist drill also has two margins, which enable proper guidance and locating of the drill while it is in operation.The tool point angle (TPA) is formed by the two lips and is chosen based on the properties of the material to be cut. The usual TPA for commercial drills is 118°, which is appropriate for drilling low-carbon steels and cast irons.For harder and tougher metals, such as hardened steel, brass and bronze, larger TPAs (130°or 140°) give better performance. The helix angle of the flutes of the commonly used twist drills ranges between 24°and 30°. When drilling copper or soft plastics, higher values for the helix angle are recommended (between 35°and 45°).Twist drills are usually made of high-speed steel, although carbide-tipped drills are also available. The sizes of twist drills used in industrial practice range from 0.01 up to 3.25 in. (i. e., 0.25 up to 80 mm).Core drills. A core drill consists of the chamfer, body, neck, and shank. This type of drill may have either three or four flutes and equal number of margins, which ensure superior guidance, thus resulting in high machining accuracy.that a core drill has flat end. The chamfer can have three or four cutting edges or lips, and the lip angle may vary between 90°and 120°.Core drills are employed for enlarging previously made holes and not for originating holes. This type of drill is characterized by greater productivity, high machining accuracy, and superior quality of the drilled surfaces.Gun drills. Gun drills are used for drilling deep holes. All gun drills arestraight-fluted, and each has a single cutting edge. A hole in the body acts as a conduit to transmit coolant under considerable pressure to the tip of the drill.There are two kinds of gun drills, namely, the center-cut gun drill used for drilling blind holes and the trepanning drill. The latter has a cylindrical groove at its center, thus generating a solid core, which guides the tool as it proceeds during the drilling operation.Spade drills. Spade drills are used for drilling large holes of 3.5 in.(90mm) or more. Their design results in a marked saving in cost of the tool as well as a tangible reduction in its weight, which facilitates its handling. Moreover, this type of drill is easy to grind.Milling and Milling CutterMilling is a machining process that is carried out by means of a multiedge rotating tool known as a milling cutter.In this process, metal removal is achieved through combining the rotary motion of the milling cutter and linear motions of the workpiece simultaneously. Milling operations are employed in producing flat, contoured and helical surfaces as well as for thread- and gear-cutting operation.Each of the cutting edges of a milling cutter acts as an individual single-point cutter when it engages with the workpiece metal. Therefore, each of those cutting edges has appropriate rake and relief angles.Since only a few of the cutting edges are engaged with the workpiece at a time, heavy cuts can be taken without adversely affecting the tool life. In fact, the permissible cutting speeds and feeds for milling are three to four times higher than those for turning or drilling.Moreover, the quality of the surfaces machined by milling is generally superior to the quality of surfaces machined by trning, shaping, or drilling.A wide variety of milling cutters is available in industry. This, together with the fact that a milling machine is a very versatile machine tool, makes the milling machine the backbone of a machining workshop.As far as the direction of cutter rotation and workpiece feed are concerned, milling is performed by either of the following two methods.Up milling (conventional milling). In up milling the workpiece is fed against the direction of cutter rotation. As we can see in that figure, the depth of cut (and consequently the load) gradually increases on the successively engaged cutting edges.Therefore, the machining process involves no impact loading, thus ensuring smoother operation of the machine tool and longer tool life. The quality of the machined surface obtained by up milling is not very high. Nevertheless, up milling is commonly used in industry, especially for rough cuts.Down milling (climb milling).In down milling the cutter rotation coincides with the direction of feed at the contact point between the tool and the workpiece. It can also be seen that the maximum depth of cut is achieved directly as the cutter engages with the workpiece.This results in a kind of impact, or sudden loading. Therefore, this method cannot be used unless the milling machine is equipped with a backlash eliminator on the feed screw. The advantages of this method include higher quality of the machined surface and easier clamping of workpieces, since the cutting forces act downward.Types of Milling CuttersThere is a wide variety of milling cutter shapes. Each of them is designed to perform effectively a specific milling operation.Generally, a milling cutter can be described as a multiedge cutting tool having the shape of a solid of revolution, with the cutting teeth arranged either on theperiphery or on an end face or on both. Following is a quick survey of the commonly used types of milling cutters.Plain milling cutter. A plain milling cutter is a disk-shaped cutting tool that may have either straight or helical teeth. This type is always mounted on horizontal milling machines and is used for machining flat surfaces.Face milling cutter. A face milling cutter is also used for machining flat surfaces. It is bolted at the end of a short arbor, which is in turn mounted on a vertical milling machine.Plain metal slitting saw cutter.Indicates a plain metal slitting saw cutter. we can see that it actually involves a very thin plain milling cutter.Side milling cutter. A side milling cutter is used for cutting slots, grooves, and splines.It is quite similar to the plain milling cutter, the difference being that this type has teeth on the sides. As is the case with the plain cutter, the cutting teeth can be straight or helical.Angle milling cutter. An angle milling cutter is employed in cutting dovetail grooves, ratchet wheels.T-slot cutter. A T-slot cutter involves a plain milling cutter with an integral shaft normal to it. As the name suggests, this type is used for milling T-slots.End mill cutter. End mill cutters find common applications in cutting slots, grooves, flutes, splines, pocketing work, and the like.Indicates an end mill cutter. The latter is always mounted on a vertical milling machine and can have two or four flutes, which may be either straight or helical.Form milling cutter. The teeth of a form milling cutter have a certain shape, which is identical to the section of the metal to be removed during the milling operation. Examples of this type include gear cutters, gear hobs, convex and concave cutters, and the like. From milling cutters are mounted on horizontal milling machines.Materials of Milling CuttersThe commonly used milling cutters are made of high-speed steel, which is generally adequate for most jobs.Milling cutters tipped with sintered carbides or cast nonferrous alloys as cutting teeth are usually employed for mass production, where heavier cuts and/or high cutting speeds are required.It has already been stated that the workpiece must be located relative to the cutting tool, and be secured in that position. After the workpiece has been marked out,it is still necessary to position it with respect to the machine movements, and to clamp it in that position before machining is started.When several identical workpieces are to be produced the need to mark out each part is eliminated by the use of jigs and fixtures, but if a casting or forging is involved, a trial workpiece is marked out, to ensure that the workpiece can be produced from it, and to ensure that ribs, cores, etc. have not become misplaced.Jigs and fixtures are alike in that they both incorporate devices to ensure that the workpiece is correctly located and clamped, but they differ in that jigs incorporate means of tool guiding during the actual cutting operation, and fixtures do not.In practice, the only cutting tools that can be guided while actually cutting are drills, reamers, and similar cutters; and so jigs are associated with drilling operations, and fixtures with all other operations. Fixtures may incorporate means of setting the cutting tools relative to the location system.The advantages of jigs and fixtures can be summarised as follows:1)Marking out and other measuring and setting out methods are eliminated;2)Unskilled workers may proceed confidently and quickly in knowledge that the workpiece can be positioned correctly, and the tools guided or set;3)the assembly of parts is facilitated, since all components will be identical within small limits, and “trying” and filing of work is eliminated;4)The parts will be interchangeable, and if the product sold over a wide area, the problem of spare parts will be simplified.Bolt holes often have 1.5mm or even 3.0mm clearance for the bolt, and the reader may doubt the necessity of making precision jigs for such work. It must be remembered that the jigs, once made, will be used on many components, and the extra cost of an accurately made jig is spread over a large output.Furthermore, it is surprising how small errors accumulate in a mechanism during its assembly. When a clearance is specified, it is better to ensure its observance, rather than to allow careless marking out and machining to encroach upon it．1) The location of workpiece. Represents a body that is completely free in space. In this condition it has six degrees of freedom. Consider these freedoms with respect to the three mutually perpendicular axes XX, YY, and ZZ.The body can move along any of these axes; it therefore has three freedoms of translation. It can also rotate about any of the three axes; it therefore has three freedoms of rotation. The total number of freedoms is six. When work is located, asmany of these freedoms as possible must be eliminated, to ensure that the operation is performed with the required accuracy.Accuracy is ensured by machining suitable location features as early as possible, and using them for all location, unless other considerations mean that other location features must be used. If it is necessary, the new location features must be machined as a result of location from the former location features.2) The clamping of the workpiece. The clamping system must be such that the workpiece is held against the cutting forces, and the clamping forces must not be so great as to cause the workpiece to become distorted or damaged.The workpiece must be supported beneath the point of clamping, to ensure that the forces are taken by the main frame of the jig or fixture, and on to the machine table and bed. When jigs and fixtures are designed, the clamping system is designed to ensure that the correct clamping force is applied, and that the clamps can be operated quickly but with safety.Definition of a Drill JigA drill jig is a device for ensuring that a hole to be drilled, tapped, or reamed in a workpiece will be machined in the proper place.Basically it consists of a clamping device to hold the part in position under hardened-steel bushings through which the drill passes during the drilling operation. The drill is guided by the bushings.If the workpiece is of simple construction, the jig may be clamped on the workpiece. In most cases, however, the workpiece is held by the jig, and the jig is arranged so that the workpiece can be quickly inserted and as quickly removed after the machining operation is performed.Jigs make it possible to drill, ream, and tap holes at much greater speeds and with greater accuracy than when the holes are produced by conventional hand methods. Another advantage is that skilled workers are not required when jigs are used. Responsibility for the accuracy of hole location is taken from the operator and given to the jig.The term jig should be used only for devices employed while drilling, reaming, or tapping holes. It is not fastened to the machine on which it is used and may be moved around on the table of the drilling machine to bring each bushing directly under the drill. Jigs physically limit and control the path of the cutting tool.If the operation includes machining operations like milling, planing, shaping, turning, etc., the term fixture should be used. A fixture holds the work duringmachining operations but does not contain special arrangements for guiding the cutting tool ,as drill jigs do.Typical Jigs and FixturesTypical drill jig. Illustrates a drilling jig for drilling four holes in the flange of a workpiece that has been completed except for the four holes.The workpiece has an accurately machined bore, and is located from the bore and the end face, from a cylindrical post. There is no need to control the rotational position about the axis of the bore, because up to the time when the holes are drilled, it is symmetrical about that axisThe four bushes used to control the drill are held in the drill plate, which, with the hand nut, is used to clamp the workpiece against the base of the fixture.Typical milling fixture. Figure 13.3 illustrates a simple milling fixture for milling the slot in the otherwise completed workpiece shown. The workpiece is located from two of the four holes in its base, and from the underside of the base.The workpiece is clamped in position, and cutter is located against the setting block, which provides setting or cutter position and depth of cut.The fixture must be positioned relative to the machine table, The fixture is secured to the machine table with T-bolts, also engaging in the slots in the table.机械加工及其加工工具钻削和钻头钻削就是通过迫使绕自身轴线旋转的切削刀具进入工件而在其上生成通孔或盲孔。

微孔的加工方法正如宏观加工一样，在微观加工中孔的加工也许也是最常用的加工之一。

孔的加工方法有很多种，每一种都有其优点和缺点，这主要取决于孔的直径、深度、工作材料和设备要求。

这篇文章主要介绍了内冷却钻头钻孔、无冷却钻孔、插铣、电火花以及激光加工微孔的几种方法。

易于孔加工的操作无论孔有多大，在加工时将冷却液导入到刀尖，这都有助于排屑并能降低刀具和工件表面产生的摩擦热。

尤其是在加工深细孔时，有无冷却液对加工的影响更大，因为深细孔加工的刀具比较脆弱，再加上刀具对切屑的二次切削和切屑的堆积会积累大量的热，而热量是碳化物刀具的主要“天敌”，它会加快刀具的失效速度。

当使用外冷却液时，刀具本身会阻止切削液进入切削加工位置。

也就是到3-5倍的直径深度后切削液就会很难流入到刀尖。

副哈维工具有限公司的副总工程师杰夫戴维斯说，这时就该选用带有内冷却液的钻头。

另外，在加工小孔时采用的外冷却液的冷却方式产生的利要大于弊，当钻头进入工件时，已经流入孔的冷却液产生的压力有时会缴坏钻头，戴维斯说。

刀具生产商提供的标准钻头的直径从0.039到0.125英寸，能加工深度小雨12倍的直径的深孔，同时提供直径从0.002到0.020英寸的不带内冷却液的钻头。

尽管有内冷却能力，但还是不够的，冷却液需要一定的流动速度从而能够将切屑清出孔外。

戴维斯强调，冷却液的最低压力应为600-800磅/平方英寸，加工状况还会随着所施加的压力的增加而提高，他补充道。

为了防止这些冷却液通口被杂物堵塞，戴维斯还推荐在钻头加上一5微米孔径或更加精密的冷却液滤清器。

另外，他还推荐在加工孔时有必要在工件的上方先技工一个定心或导向孔，以防止刀具偏斜，并有助于保证所加工孔的垂直度。

当选用定心钻时，应使选择的定心钻刀尖上的坡口角小于等于其后内冷钻的坡口角。

定心钻的直径还要稍微大一些。

例如，如果定心钻的坡口角为120，内冷却钻头的坡口角为140，并且定心钻的直径小于内冷却钻的直径。