外文资料翻译系别. 专业. 班级. 姓名. 学号. 指导教师.2011年4 月一、China’s mold industryDue to historical reasons for the formation of closed, "big and complete" enterprise features, most enterprises in China are equipped with mold workshop, in factory matching status since the late 70s have a mold the concept of industrialization and specialization of production. Production efficiency is not high, poor economic returns. Mold production industry is small and scattered, cross-industry, capital-intensive, professional, commercial and technical management level are relatively low.According to incomplete statistics, there are now specialized in manufacturing mold, the product supporting mold factory workshop (factory) near 17 000, about 600 000 employees, annual output value reached 20 billion yuan mold. However, the existing capacity of the mold and die industry can only meet the demand of 60%, still can not meet the needs of national economic development. At present, the domestic needs of large, sophisticated, complex and long life of the mold also rely mainly on imports. According to customs statistics, in 1997 630 million U.S. dollars worth of imports mold, not including the import of mold together with the equipment; in 1997 only 78 million U.S. dollars export mold. At present the technological level of China Die & Mould Industry and manufacturing capacity, China's national economy in the weak links and bottlenecks constraining sustainable economic development.1、Research on the Structure of industrial products moldIn accordance with the division of China Mould Industry Association, China mold is divided into 10 basic categories, which, stamping die and plastic molding two categories accounted for the main part. Calculated by output, present, China accounts for about 50% die stamping, plastic molding die about 20%, Wire Drawing Die (Tool) about 10% of the world's advanced industrial countries and regions, the proportion of plastic forming die die general of the total output value 40%.Most of our stamping die mold for the simple, single-process mode and meet the molds, precision die, precision multi-position progressive die is also one of the few, die less than 100 million times the average life of the mold reached 100 million times the maximum life of more than accuracy 3 ~ 5um, more than 50 progressive station, and the international life ofthe die 600 million times the highest average life of the die 50 million times compared to the mid 80s at the international advanced level.China's plastic molding mold design, production technology started relatively late, the overall level of low. Currently a single cavity, a simple mold cavity 70%, and still dominant.A sophisticated multi-cavity mold plastic injection mold, plastic injection mold has been able to multi-color preliminary design and manufacturing. Mould is about 80 million times the average life span is about, the main difference is the large deformation of mold components, excess burr side of a large, poor surface quality, erosion and corrosion serious mold cavity, the mold cavity exhaust poor and vulnerable such as, injection mold 5um accuracy has reached below the highest life expectancy has exceeded 20 million times, the number has more than 100 chamber cavity, reaching the mid 80s to early 90s the international advanced level.2、mold Present Status of TechnologyTechnical level of China's mold industry currently uneven, with wide disparities. Generally speaking, with the developed industrial countries, Hong Kong and Taiwan advanced level, there is a large gap.The use of CAD / CAM / CAE / CAPP and other technical design and manufacture molds, both wide application, or technical level, there is a big gap between both. In the application of CAD technology design molds, only about 10% of the mold used in the design of CAD, aside from drawing board still has a long way to go; in the application of CAE design and analysis of mold calculation, it was just started, most of the game is still in trial stages and animation; in the application of CAM technology manufacturing molds, first, the lack of advanced manufacturing equipment, and second, the existing process equipment (including the last 10 years the introduction of advanced equipment) or computer standard (IBM PC and compatibles, HP workstations, etc.) different, or because of differences in bytes, processing speed differences, differences in resistance to electromagnetic interference, networking is low, only about 5% of the mold manufacturing equipment of recent work in this task; in the application process planning CAPP technology, basically a blank state, based on the need for a lot of standardization work; in the mold common technology, such as mold rapid prototyping technology, polishing, electroforming technologies, surface treatment technologyaspects of CAD / CAM technology in China has just started. Computer-aided technology, software development, is still at low level, the accumulation of knowledge and experience required. Most of our mold factory, mold processing equipment shop old, long in the length of civilian service, accuracy, low efficiency, still use the ordinary forging, turning, milling, planing, drilling, grinding and processing equipment, mold, heat treatment is still in use salt bath, box-type furnace, operating with the experience of workers, poorly equipped, high energy consumption. Renewal of equipment is slow, technological innovation, technological progress is not much intensity. Although in recent years introduced many advanced mold processing equipment, but are too scattered, or not complete, only about 25% utilization, equipment, some of the advanced functions are not given full play.Lack of technology of high-quality mold design, manufacturing technology and skilled workers, especially the lack of knowledge and breadth, knowledge structure, high levels of compound talents. China's mold industry and technical personnel, only 8% of employees 12%, and the technical personnel and skilled workers and lower the overall skill level. Before 1980, practitioners of technical personnel and skilled workers, the aging of knowledge, knowledge structure can not meet the current needs; and staff employed after 80 years, expertise, experience lack of hands-on ability, not ease, do not want to learn technology. In recent years, the brain drain caused by personnel not only decrease the quantity and quality levels, and personnel structure of the emergence of new faults, lean, make mold design, manufacturing difficult to raise the technical level.mold industry supporting materials, standard parts of present conditionOver the past 10 years, especially the "Eighth Five-Year", the State organization of the ministries have repeatedly Material Research Institute, universities and steel enterprises, research and development of special series of die steel, molds and other mold-specific carbide special tools, auxiliary materials, and some promotion. However, due to the quality is not stable enough, the lack of the necessary test conditions and test data, specifications and varieties less, large molds and special mold steel and specifications are required for the gap. In the steel supply, settlement amount and sporadic users of mass-produced steel supply and demand contradiction, yet to be effectively addressed. In addition, in recent years have foreign steel mold set up sales outlets in China, but poor channels, technical services supportthe weak and prices are high, foreign exchange settlement system and other factors, promote the use of much current.Mold supporting materials and special techniques in recent years despite the popularization and application, but failed to mature production technology, most still also in the exploratory stage tests, such as die coating technology, surface treatment technology mold, mold guide lubrication technology Die sensing technology and lubrication technology, mold to stress technology, mold and other anti-fatigue and anti-corrosion technology productivity has not yet fully formed, towards commercialization. Some key, important technologies also lack the protection of intellectual property.China's mold standard parts production, the formation of the early 80s only small-scale production, standardization and standard mold parts using the coverage of about 20%, from the market can be assigned to, is just about 30 varieties, and limited to small and medium size. Standard punch, hot runner components and other supplies just the beginning, mold and parts production and supply channels for poor, poor accuracy and quality.3、Die & Mould Industry Structure in Industrial OrganizationChina's mold industry is relatively backward and still could not be called an independent industry. Mold manufacturer in China currently can be divided into four categories: professional mold factory, professional production outside for mold; products factory mold factory or workshop, in order to supply the product works as the main tasks needed to die; die-funded enterprises branch, the organizational model and professional mold factory is similar to small but the main; township mold business, and professional mold factory is similar. Of which the largest number of first-class, mold production accounts for about 70% of total output. China's mold industry, decentralized management system. There are 19 major industry sectors manufacture and use of mold, there is no unified management of the department. Only by China Die & Mould Industry Association, overall planning, focus on research, cross-sectoral, inter-departmental management difficulties are many.Mold is suitable for small and medium enterprises organize production, and our technical transformation investment tilted to large and medium enterprises, small and medium enterprise investment mold can not be guaranteed. Including product factory mold shop,factory, including, after the transformation can not quickly recover its investment, or debt-laden, affecting development.Although most products factory mold shop, factory technical force is strong, good equipment conditions, the production of mold levels higher, but equipment utilization rate.Price has long been China's mold inconsistent with their value, resulting in mold industry "own little economic benefit, social benefit big" phenomenon. "Dry as dry mold mold standard parts, standard parts dry as dry mold with pieces of production. Dry with parts manufactured products than with the mold" of the class of anomalies exist.二、Basic terminology1、ImpressionThe injection mould is an assenbly of parts containing within an inpression into which plastic material is injected and cooled. It is the impression which gives the moulding its form. The impression may, therefore, be defined as thatpart of the mould which imparts shape to the moulding.The impression is formed by two mould mimbers:(i)The cavity, which is the female portion of the mould, gices the moulding itsexternal form.(ii)The core, which is the male portion of the mould , forms the internal shape of the moulding.2、Cavity an core platesThe basic mould in this case consists of two plates. Into one plate is sunk the cavity which shapes the outside form of the moulding and os therefore known as the cavity plate. Similarly, the core which projects form the core plate forms the inside shape of the moulding os closed, the two plates come together forming a space between the cavity and core which is the impression.3、Sprue bushDuring the injection process plastic material is delivered to the mozzle of the machie as a melt;it is then tramsferred to the impression though a passage. The material in this passage is termed the sprue, and the bush is called a sprue bush.4、Runner and gate systemsThe material may bedirectly injected into the impression though the sprue bush or for moulds containing several impressions it may pass from the sprue bush hole through a runnerand gate system therefore entering the impression.5、Register ringIf the material is to pass without hidrance into the mould the mozzle and sprue must be correctly aligned. To endure that this is so the mould must be central to the machine and this can be achieved by including a regicter ring.6、Guide pillars and bushesTo mould an even-walled article it is necessary to ensure that the cavity and core are keptin alignmemt. This is done by incorporating guide pillars on one mould plate which then enter corresponding guide bushes in the other mould plate as the mouls closes.7、Fixed half and moving halfThe various mould parts fall naturally into two sections or halves. Hence, that half attached to the stationary platen of the machine (indicated by the chain dotted line)is termed the fixed half, The other half of the mould attached to the moving platen of the machine is known simply as the moving half. Now it has to be situsted. Generally the core is situated in the moving half and the overriding reason why this is so, is as follows:The moulding as it cools, will shrink on to the core and remain with it as the mould opens. This will occur irrespective of whether the core is in the fixed half or the moving half. However, this shrinkage on to the core means that some form of ejector system is almostly certainly necessary. Motivation for this ejector system iseasily provided if the core is in the moving half. Moreover, in the case of our single-impression basic mould, where a direct sprue feed to the underside of the moulding is desired the cavity must be in the fixed half and the core in the moving half.8、Methods of incorporating cavity and coreWe have now seen that in general the core is incorporsted in the moving half and the cavity in the fixed half. However, there are various methods by which the cavity and core can be incorporated in their respective halves of the mould. These represent two basic alternatives (i) the integer method where the cavity and core can be machined form steel plates which become part of the structural build-up of the mould, or (ii) the cavity and core can be machined form small blocks of steel, termed inderts, and subsequently bolstered. The choice between these alternatives constitutes an important decision on the part of the mould designer. The final result, nevertheless, will be the contains the core is termed the core plate and the plate or assembly which contains the cavity is termed the cavity plate.9、Cavity FabricationWhen a decision for making a mold is made, the cost is predicated on producing aspecified quantity of parts without additional tooling expenditure. Sometimes, the anticipatesare quantities are exceeded; other times, they all short of requirements, and costly repairs becomenecesary in order to supply the needs.In the making of cavities by machining, grinding, or electric discharge machining, there is constant drive to improve the rate of metal removal. Cutting tools as well as machine tools are developed for heavier and faster cuts; grinding wheels are tailor-made for special steels to allow deeper cuts per pass; and EDM machines are revamped to burn the metal at an accelerated pace.It is fully appreciated that faster mental-removal rate leads to more economical manufacture,but at the same time it mast be recognized that the newer cavity fabrication is associated with generation of more heat and indirectly with higher stresses that if not relieved can cause premature gailure.Suppliers of tool steel caution the user against fabricating stresses and strongly advise a stress-relieving operation. When a steel is to be heat-treated and a preheat cycle ia part of the heat-treating specification, then the metal-removal stresses will be eliminated.A great number of cavities are made of prehardened steel, and therefore would not be heat-treated.For those cavities,a stress-relieving operation should be carried out immediately after fabricaton.the stress-relieving temperature as a rule is about 100ºF below the tempring heat and is held for 30 min. for each inch of steel thickness. It is best to check the stress-relieving heat and time with the maker of the steel.The information about fabrication stress has always been emphasized by the steelmakers,but for some reason it has not been given the attention it deserves. Since a tool drawing should cover all the requirements of a tool element, it would be the appropriate place for a note such as the following:Note: For heat-treated steel:“Note: Use preheat and harden to RC ____.”Note: For prehardened steel:“Note: Stress relieve@___ºF for____hoursper____ inch of thickness.”Every effort should be made to eliminate the invisible source of problems, namely，fabricating stresses.Mold cavities can be produced by a variety of processes. The process to be used is Determined.First of all by the lowest cost at which the cavity can be produced for the desired end result. Other factors include precision of repairability. Frequently, a combination of processes is employed in order to meet all the specified requirements. The most common processes are discussed in the following sections.Specifically, investment casting may be considered for applications where the number of cavities is greater than six and tolerances of dimensions are in the range of ±0.005. It isparticularly adaptable to complex shapes and unusual configurations as well as for surface that are highly decorative and difficult to obtain by conventional processes. These decorative surface may have a wood grain, leather grain, or textured surface suitable for handle grips,etc.A lmost any alloy of steel or beryllium copper alloys can be cast to size and heat-treated metal hardness that is within the range of the alloy being cast. Acomparative cost evaluation will in many cases favor the investment process. The investment cast tooling when produced by qualified people can be of the same quality as those machined from bar stock., i.e.,they can be free of porosity, proper hardness, uniform with respect to each other, and where (and-where)the time element is a factor-can be produced in days instead of weeks. In this process, cavities have been made that weigh as much as 750 lb.The investment caqsting method calls for a model of a low-melt material such as wax, plastic, or frozen mercury. The model is a reproduction of the desired cavity block and, when cast, is ready for mounting in the base. It incorporates shrinkage allowances as well as a gating system for metal pouring. The complete model is sipped in a slurry of fine refractory material and then encased in the investment material, which may be plaster of paris or mixtures of ceramic materials with high refractory properties. With the encased investment fully set up, the model is removed from the mold by heating in can over to liquefy the meltable material and cause it to run out. The molten material is reclaimed for further use. The mold or investment casing is fully dried out during the heating. After these steps, the investment is preheated to 1000°to 2000ºF in preparation for the pouring of the metal. The preheat temperature is governed by the type of metal. When pouring is completed and solidification of the metal has taken place, the investment material is broken away to free the casting for removal of the gates and cleaning.The making of the model for cavity and core blocks of meltable material is an intermediate step. These model blocks are cast in molds that are the staring point for the process. The starting-point mold consists of the part cavity or core where the parting line width as well as block portin for mounting, etc., are built around the part cavity and core, and thus form the shape needed as the complete block.The investment-casting process was developed commercially to a high dehree of precision and quality during World War II for the manufacture of aviation gasturbine blades were made of alloys, which were difficult or impossible to be foged. Subsequently, refinements have been developed in the investment-casting process that are especially valuable to the moldmaking field. Most these improvements are in the area of investment materials for the pyrpose of maintaining closer tolerances on the castings. Some mold shops have equippedthemselves with the ability to produce investment castings alongside their regular fabrication facilities.三、Feed SystemIt is necessary to paovide a flow-way in the injection mould to connect the nozzle of the injection machine to each impression. This flow-way is termed the feed system. Normally the feed system comprises a sprue, runner and gate. These terms apply equally to the flow-way itself, and to the molded material which is removed from the flow-way itself in the process of extracting the molding.1、SprueA spure is a channel though which to transfer molten plastic injected from the nozzle of the injector the mold. It is a part of spure bush, which is a separate part from th mold.2、RunnerA runner is a channel that guides molten plastic into the cavity of a mold.3、GateA gate is an entrance through which molten plastic enters the cavity. The gate has the following functions:restricts the flow and the direction of molten plastic;simplifies cutting of a runner and moldings to simplify finishing of parts;quickly cools and solidifies to avoid backflow after molten plastic has filled up in the cavity.4、Cold slug wellThe purpose of the cold slug well, shown oppwsite the sprue, is theoretically to receive the material that has chilled at the front of the nozzle during the cooling and ejection phase. Perhaps of greater importance is the fact that it provides positive means whereby the sprue can be pulled from the sprue bush for ejection purposes.The sprue, the runner, and the gate will be discarded after a part is complete. However, the runner and the gate are important items that affect the quality or the cost of parts.四、Parting SurfaceThe parting surfaces of a mould are those portion of both mould plates, adjacent to the impressions, which butt together to form a seal and prevent the loss of plastic material from the impression. The parting surface is 1、classified flat and non-flatThe mature of the parting surface depends entirely on the shape of the component. A further consideration os that the parting surface must be chosen so that the molding can be removed from the mould. Many molding are required which have a parting line which lies ona non-planar or curved surface.When the parting surface os not flat, there is the quertion of unbalanced forces to consider in certain instances. The plastic material when under pressure within the impression, will exert a force which will tend to open the mould in the lateral direction. If this happens some flashing may occur on the angled face. The movement between the two mould halves will be resisted by the guide pillars, but even so, because of the large forced involved, it is desirable to balance the mould by reversing the step so that the parting surface continues across the mould as a mirror image of the section which includes the impression. It is often convenient to spercify an even number of impressions when considering this type of mould, as impressions positioned on opposite sides of the mould‟s centre-line serve to balance the mould.五、Mould coolingOne fundamental principle of injection molding os that hot material enters the mouls, where it cools rapidly to a temperature at which it solidified sufficiently to retain the shape of the impression. The temperature of the mould os therefore important as it governs a portion of the overall molding cycle. While the melt flows more freely in a hot mould, a greater cooling period is required before the solidified molding can be ejected. Alternatively, while the melt solidifies quickly in a cold mould it may not reach the extremities of the impression. A compromise between the two extremes must therefore be accepted to obtain the optimum molding cycle.The operating temperature for a particular mould will depend on a number of factors which include the following:type and grade of material to be molded;length of flow within the impression;wall section of the molding;length of the feed system, etc. It is often found advantageous to use a slightly higher temperature than is required just to fill the impression, as this tends to impreove the surface finish of the molding by minimizing weld lines, flow marks and other blemishes.To maintain the required temperature differential between the mould and plastic material, water or other fluid is circulated through holes or channels within the mould. These holes or channels are termed flow-ways or water-ways and the complete system of flow ways is termed the circuit.During the impression filling stage the hottert material will be in the vicinity of the entry point, i. e. the gate, the coolest material will be at the point farthest from the entry. The temperature of the coolant fluid, however, increases as it passes though the mould. Thereforeto achieve an even cooling rate over the molding surface it is necessary to locate the incoming coolant fluid adjacent to…hot‟molding surfaces and to locate the channels containing…heated‟coolant fluid adjacent to …cool‟molding surfaces. However, as will be seen from the following discussion, it is not always practicable to adopt the idealized appreach and the designer must use a fair amount of common sense when laying out coolant circuits if unnercessarily expensive moulds are to be avoided.Units for the circulation of water and other fluids are commercially available. These units are simply connected to the mould via flexible hoses, with these units the mould‟s temperature can be maintained within close limits. Close temperature control is not possible using the alternative system in which the mould is connected to a cold water supply.It is the mould designer‟s responsibility to provide an adequate circulating system within the mould. In general, the simplest systems are those in which holes are bored longitudinally through the mould plates. However, this is not necessarily the most dfficient method for a particular mould.When using drillings for the circulation of the coolant, however, these must not be positioned too close to the impression say closer than 16mm as this is likely to cause a marked temperature66variation across the impression, with resultant molding problems.The layout of a circuit is often complicated by the fact that flow ways must not be drilled too close to any other hole in the same mould plate. It will be recalled that the mould plate has a large number of holes or recessers, to accommodate ejector pins, guide pillars, guide bushes, sprue bush, inserts, etc. How close it is safe to position in a flow way adjacent to another hole depends to a large extent on the depth of the flow way driolling required. When drilling deep flow ways there is a tendency for the drill to wander off its prescribed course. A rule which is often applied is that for drillings up to 150mm deep the flow way should not be closer than 3 mm to any other hole. For deeper flow ways this allowance is increased to 5 mm.To obtain the best possible position for a circuit it is good practice to lay the circuit in at the earliest opportunity in the design. The other mould itens such as ejector pins, guide bushes, etc. , can then be positioned accordingly.六、Designs CAD/CAMAlthough CAD/CAM manufactures and suppliers are addressing the challenges mold disigners face when using software, these designers are still grappling with a number of issues. Kevin Crystal, senior quality engineer with The Protomold Co. (Maple Plain, MN)-a rapid injection molding company-reports that the greatest challenges he faces are with file。
