模具毕业设计外文翻译
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Die Life of cold stamping die and mprovementsOverview of stamping dieStamping Die - Stamping in the cold, the material (metal or non-metallic) processing into parts (or half) of a special technical equipment, called cold stamping die (commonly known as Die). Press - is at room temperature, using the die installed in the press to put pressure on the material to produce a separation or plastic deformation, and thus to obtain the necessary parts of a pressure processing method.Stamping die in the form of many, the general categories according to the following main features:1. According to the technical nature of(1) Die along the closed or open contour the material are derived from mold. If blanking die, punch die, cut off the mold, cut mode, cutting mode, split mode, etc..(2) bending mode to blank or blank sheet along a straight line (curved line) to bend, deform, and thus obtain a certain angle and shape of the workpiece in the mold.(3) The drawing die is made of the blank sheet opening hollow, or hollow pieces of further changes to the shape and size of the mold.(4) Die rough or semi-finished workpiece is convex according to plan, direct copy the shape of the die shape, the material itself, generate only local plastic deformation of the mold. Such as the bulging mode, reducing the die, expansion die, forming die rolling, flanging mold, plastic mold.2. According to the degree classification process combination(1) single process model in a press tour, just completed a die stamping process.(2) composite model is only one station, in a press tour, at the same station at the same time to complete more than two or two die stamping process.(3) Progressive Die (also known as the modulus of continuity) in the feeding direction, rough, with two or more of the station, at the press of a visit, work in different places on the completion of two or two successive Road over stamping die process.Chong called cold stamping die Die-wide.Cold stamping die is used in cold stamping die mold industry, and accessories required for high-performance structural ceramic materials, preparation methods, high-performance ceramic materials, molds and accessories from the zirconium oxide and yttrium aluminum powder increases, Pr element composition, Preparation is the solution of zirconia, yttria solution, praseodymium oxide solution, according to a certain percentage of alumina solution when mixed liquor, ammonium bicarbonate infusion, by co-precipitation synthesis of ceramic materials, molds and accessories needed for raw materials, reaction precipitate generated by the treatment, drying, calcining and accessories by high performance ceramic mold material superfine powder, and then after forming, sintering, finishing, they will have high-performance ceramic materials,molds and accessories. Advantages of this invention is the invention made of cold stamping dies and parts and long service life, the process does not appear in the press and its parts and stamping die bond generated the phenomenon of stamping surface is smooth, no glitches, can replace traditional high-speed steel, tungsten steel.Die with the main partsDie stamping tools is the main process equipment, stamping rely on the relative movement under the mold completed. Processing time because the upper and lower mold between the constant division and, if continued operation of the fingers of workers to enter or remain in the mold closed, there will certainly pose a serious threat to their personal safety.(A) of the mold main parts, function and safety requirements1. Working parts is a direct punch to blank forming the working parts, therefore, it is the key to mold parts. Punch not only sophisticated and complex, it should meet the following requirements:(1) be of sufficient strength, can not be broken or destroyed during stamping.(2) should be appropriate to its material and heat treatment requirements, to prevent too high hardness and brittle fracture.2. Positioning parts positioning part is to determine the location of the parts installed blank, there are pins (board), gauge pin (plate), lead is sold, guide plate, knife set from the side, side pressure etc.. Design should be considered when positioning parts easy to operate and should not have had orientation, location to facilitate observation, preferably in the forward position, contouring to correct the pin location and positioning.3. Binder, unloading and discharging parts binder components are blank holder, binder board. Blank holder pressure can drawing blank holder force, thereby preventing billets under the action of the tangential pressure arch formed folds. The role of pressure plate to prevent movement and bounce blank. Top of the device, discharge board's role is to facilitate the pieces and clean up waste. Them by the spring, rubber and equipment, putting on the air-cushion support, can move up and down, knocking out pieces of the design should have enough top output, movement to the limited spaces. Stripper plate area should be minimized or closed position in the operating groove milling out empty-handed. Exposure of the stripper plate should have protection around the plate, to prevent finger inserted into or foreign objects inside, exposed surface edges should be blunt down.4. Guide parts and guide sleeve guide pin is the most widely used part of a guide. Its role is to ensure punch the punching clearance when accurate match. Therefore, the guide posts, guide cover the gap should be less than the blanking clearance. Guide Post located next mold base, to ensure that the stroke bottom dead center, the lead column in the template on the face over the top for at least 5 to 10 mm. Guide columns should be arranged far away from the module and the pressure plate in the area, so the operator's arms do not get to take over the lead column material.5. Supporting and clamping the upper and lower parts which includes templates, die handle,fixed plate punch, plate, stopper, etc..Up and down the template is the basis of the cold die parts, other parts are respectively fixed at the top. Template plane size, especially around the direction to be compatible with the workpiece, too large or too small are not conducive to action.Some molds (blanking, punching type mold) to the pieces of convenience, be set up under the mold plate. At this time the best and the template plate connected between the screw, the two plate thickness should be absolutely equal. Plate spacing out the pieces to be able to prevail, not too much, so as not to break the template.6. Fastening parts which includes screws, nuts, springs, pins, washers, etc., are generally used standard parts. Die more with the amount of standard parts, design choice and flexibility should be tightened to ensure the top out of the need to avoid exposure to the surface fastener operating position, the staff and impede operation to prevent bumps.Die with the development ofSince reform and opening, with the rapid development of the national economy, the market demand with the growing Die. In recent years, Die with the industry has been around 15% growth rate of the rapid development of industrial enterprises with ownership Die components also changed dramatically, in addition to the professional mold factory outside of state-owned, collective, joint ventures, wholly-owned and private has been a rapid development.As with the accelerating pace of international integration, the increasing competition in the market, it has been increasingly recognized product quality, cost, and new product development capacities. The cold die manufacturing is the most basic elements of the chain, one of the cold die manufacturing technology to measure a country's manufacturing sector has become an important symbol of the level, and largely determine the viability of enterprises.Die with enterprises to increase in recent years many technological advances for investment, technological progress will be seen as an important driving force for enterprise development. Some domestic enterprises have popularized the two-dimensional mold CAD, and gradually began to use UG, Pro / Engineer, I-DEAS, Euclid-IS and other international common software, individual manufacturers have also introduced Moldflow, C-Flow, DYNAFORM, Optris and MAGMASOFT etc. CAE software, and successfully applied in stamping die design.A car cover mold as the representative of a large stamping die manufacturing technology has made great progress, Dongfeng Motor Corporation mold factory, mold manufacturers such as FAW mold center has been able to produce some car cover mold. In addition, many research institutions and universities to carry out technology research and development of mold. After years of effort, in the mold CAD / CAE / CAM technology has made remarkable progress; in improving quality and reducing mold die design and manufacturing cycle, and so contributed. Although China Die with the industry over the past decade has made remarkable development, but in many ways compared with the industrialized countries there is still a large gap. Forexample, the precision machining equipment, processing equipment in Die with the relatively low proportion; CAD / CAE / CAM technology penetration is not high; many advanced mold technology not widely so, resulting in a considerable number of large, sophisticated, complex and long Die life with dependence on imports.With the continuous progress of science and technology, modern industrial production of increasingly complex and diverse, product performance and quality is ever increasing, thus the cold stamping technology put forward higher requirements. In order to adapt to the cold stamping technology industry needs, cold stamping technology itself also in innovation and development. cold stamping technology idea is to improve and expand as much as possible the advantages of the cold stamping process, to overcome its shortcomings. in the cold stamping technology development, should note the following aspects:(1) cold stamping technology process parameters should be properly identified and Die with the work of some of the shape and size, to improve the quality of stamping parts and shorten the new product production cycle should be in strengthening the metal forming the basis of theoretical studies, to metal forming theory to practice can produce a direction, and gradually establish a close connection with the actual production of the advanced process of calculation. abroad have begun to use plastic finite element method, automobile parts forming process of the stress and strain analysis and computer simulation to predict the forming part of a process plan on the possibilities and potential problems.(2) to accelerate product replacement, mold design to overcome the shortcomings of a long cycle. Should vigorously carry out computer-aided design and manufacture of molds (CAD / CAM) Research. In my country, paying particular attention to strengthening the multi-position progressive die CAD / CAM Technology.(3) to meet the needs of mass production, and reduce labor intensity. Should strengthen cold stamping of mechanized and automated, so that the average, small pieces of high-speed presses in a multi-position progressive die production, production reached a high degree of automation to further improve stamping productivity.(4) expand the scope of application of cold stamping production. So cold pressing both suitable for mass production, but also for small batch production; both the general accuracy of product production, but also can produce precision parts. Should pay attention to development such as fine blanking (especially thick material fine blanking), forming high-energy, soft mold forming, pressure and processing new superplastic forming process, but also promote the easy mode (soft mode and the low melting point alloy mold), Universal Hybrid model, the use of CNC punch press and other equipment.In addition, the performance improvement of sheet metal stamping, mold new material, die development of new processing methods should be further strengthened.Die with life and CountermeasuresDie with the life of the workpiece by punching out the number of terms. Many factors affect the life Die. There are die structure design, manufacture molds used in the punch and die materials, die quality and surface hardening heat treatment, precision die manufacturing parts and cold stamping materials selection. In addition, there are die installation, adjustment, use and maintenance.1. Die Design on Life(1) Layout design of layout methods and take the boundary value a great impact on the die life, too small to take the boundary value, often causing rapid wear and convex mold, die bite wounds on the. Starting from material savings, take the boundary value smaller the better, but take the edge is less than some value, the cut surface of the mold and the quality of life adversely. There will be left behind in the blanking die Q-gap were to produce spare parts glitch, or even damage the die edge, reduce die life. Therefore, consider increasing the material utilization of the same time, parts must yield, quality and life expectancy to determine the layout methods and take the boundary.(2) die structure prone to stress concentration on the cracking of the die structure, composite structure can be used or mosaic structure, and prestressed structure to enhance the mold life. (3) the impact of clearance when the gap is too small, compressed extrusion of interest, increased friction, increased wear, the wear side of aggravated discharge and push pieces after blanking time, materials and convex, the friction between die will cause wear and tear than the end edge on the side of the grinding much, but also easily lead to convex, concave mold temperature is high, the adsorption of metal debris in the side edge to form a metal tumor, so that male and female die chipping or expansion occurs crack phenomenon. Therefore, the gap is too small to Die Life very bad. Gap is too large will increase the punch and the die face the edge of the concentration of stress, resulting in a sharp increase in stress, so blade edge quickly lose angular yield deformation. Therefore, addition of blanking force, thereby enabling faster edge edge wear, reduce die life. But in order to reduce the male and female die wear, extending mold life, while ensuring quality of stamping pieces under the premise that larger space designed properly it is necessary.(4) Die-oriented structure of the life of a reliable guide for the working parts reduce wear, prevent male and female die bite wound is very effective. In particular, non-small-Q gap Q gap or Die, compound die and multi-position progressive die even more important. To improve the die life, must be based on processes and the demand of precision, the correct choice-oriented form and orientation accuracy, the choice should be higher than the accuracy-oriented convex, concave mold with precision.(5) the impact of cold stamping materials, cold stamping materials selected should meet the design requirements of workpieces and stamping process requirements, or easy to mold damage and reduce mold life. Poor surface quality of cold stamping, punching, cracking when the workpiece is also easy to scratch mold. Bad cold stamping plastic materials, deformation is small,easy to press when the workpiece rupture, but also easy to scratch mold. In addition, the material thickness tolerances shall comply with national standards. Die because of a certain thickness of material suitable for forming, bending, flanging, drawing die of the male and female die structure gap is directly determined by the thickness of the material. Therefore, uneven thickness, will result in waste generation and mold damage.2. Die Die Life ofDie Die Life of a mold material properties, chemical composition, structure, hardness and comprehensive reflection of metallurgical quality. Among them, the material properties and heat treatment affect the quality of the most obvious. Mold material properties on the impact of die life is great. If the same workpiece, using a different mold material of the bending test, the test results: The 9Mn2V material, the life of 5 million; with Crl2MoV nitriding, the life of up to 40 million. Therefore, the choice of materials, the batch size should be based on workpiece, rational use of mold materials. The hardness of the die parts to Die Life a great impact. But not the higher hardness, longer die life. This is because the hardness and strength, toughness and abrasion resistance are closely related. Some die demands of high hardness, long life. Such as the use of T10 steel dies, hardness 54 ~ 58HRC, only washed thousands of times a burr on the workpiece great. If the hardness to 60 ~ 64HRC, the grinding life of up to 2 to 3 million. However, if continue to improve hardness, fracture occurs earlier. Some die hardness should not be too high, as the die manufacturing using Crl2MoV 58 ~ 62HRC hardness, the general life of 2-3 million, invalid form of chipping and cracking, and if the hardness down to 54 ~ 58HRC, life expectancy increased to 5 ~ 60 000, but decreased to 50 ~ 53HRC hardness appears easy to blunt the die edge phenomenon. Thus, mold hardness must be based on material properties and failure modes may be. Should enable the hardness, strength, toughness and wear resistance, resistance to fatigue strength needed to achieve a particular stamping process the best match.3. The surface of the mold heat treatment to strengthen the quality and impact on lifeMold heat treatment the nature and quality of life of the mold a great impact. Practice shows that the die parts of the quenching distortion and cracking, early fracture during use, while the metallurgical and materials quality, forging quality, mold structure and process related, but related more to die of heat treatment. According to statistical analysis of failure causes of mold, heat treatment failure due to improper accounting for more than 50%. Practice shows that the mold material must be accompanied by high heat treatment process properly, can really play a material's potential. Parts surface hardening mold work purpose is to obtain the effect of external hard tough inside, so be hardness, wear resistance, toughness, good resistance to fatigue with. Many ways to die surface hardening, surface treatment technology of new technologies developed rapidly. In addition to Nitrocarburizing and ion nitride, boride, seepage niobium, vanadium permeability, hard chrome plated and spark strengthening, the chemical vapor deposition (CVD) and physical vapor deposition (PVD) has been gradually adopted. By CVD and PVD treatment, the mold surface covered with super-hard material, such as TiC, TiN, etc..High hardness, wear resistance, corrosion resistance, adhesion is very good, can improve the die life several times to several times.4. Manufacturing precision of the die parts of die lifePrecision die manufacturing and life in it in particular, mold surface roughness on the mold a great impact. If using Crl2MoV steel blanking die, if the surface roughness value R = 1.6 m, its life span is about 30,000. Such as polished by the precision, surface roughness value R = 0.4 m, life can be increased to 4-5 million. Therefore, the working parts of the mold surface, the general must go through grinding, grinding, polishing and other finishing and fine processing.5. Other aspects of the impact of die life(1) Press the accuracy is not high, but also easy to make die damage.(2) die in the press or not installed properly and the operator's technical level, on the tool life is also greatly affected.(3) dies in the custody and maintenance of good and bad, and the use of lubricant condition also affects mold life.6. ConclusionIn actual production, sheet metal dies for use, rare case of non-normal wear and tear. But when the die plate was found prone to irregular wear, we always study for the problems summarized. Because of a cold die, from the design, manufacture, assembly, commissioning and installation and use, all spent many hours, while the convex die, die material used, mostly high-quality alloy steel. Therefore, the die cost is relatively high. Therefore, in the production of understanding the factors that affect the die life and take the appropriate measures to guide the production of great practical significance.冷冲模具使用寿命的影响及对策冲压模具概述冲压模具--在冷冲压加工中,将材料(金属或非金属)加工成零件(或半成品)的一种特殊工艺装备,称为冷冲压模具(俗称冷冲模)。
引言概述:在现代高等教育中,毕业设计(或称为毕业论文、学士论文等)是学生完成学业的重要环节。
而对于一些特定的专业,例如翻译专业,有时候还需要完成外文翻译这一项任务。
本文将探讨毕设外文翻译的意义和目的,以及为什么对翻译专业的学生而言这一任务极其重要。
正文内容:1.提高翻译能力和技巧外文翻译是一项对翻译专业学生而言十分重要的任务,通过进行外文翻译,学生们可以通过实践提高自己的翻译能力和技巧。
在这个过程中,他们可以学习如何处理不同类型的外文文本,熟悉不同领域的专业术语,并掌握一些常用的翻译技巧和策略。
2.扩展语言和文化知识毕设外文翻译要求学生们对翻译语言的相关知识和背景有一定的了解。
在进行翻译时,学生们需要遵循目标语言的语法规则,并确保所翻译的内容准确、清晰地传达源语言的意义。
通过这一过程,学生们可以进一步扩展自己的语言和文化知识,提高自己的跨文化沟通能力。
3.提供实践机会毕设外文翻译为学生们提供了一个实践的机会,让他们能够将在课堂上所学到的理论知识应用于实际操作中。
通过实践,学生们可以对所学知识的理解更加深入,同时也可以发现并解决实际翻译过程中的问题和挑战。
这对于学生们将来从事翻译工作时具备更好的实践能力和经验具有重要意义。
4.培养翻译专业素养毕设外文翻译要求学生们具备良好的翻译专业素养。
在进行翻译过程中,学生们需要保持专业的态度和责任心,严谨地对待每一个翻译任务。
他们需要学会如何进行翻译质量的评估和控制,以确保最终翻译稿的准确性和流畅性。
这一系列的要求和实践,可以帮助学生们培养出色的翻译专业素养。
5.提升自我学习和研究能力毕设外文翻译要求学生们进行广泛的文献阅读和研究,以便更好地理解所翻译的内容,并找到适当的翻译方法和策略。
在这个过程中,学生们需要培养自己的自主学习和研究能力,提高对学术和专业领域的敏感性,并能够独立思考和解决问题。
这将对学生们未来的学术研究和进一步的职业发展产生积极的影响。
总结:引言概述:毕业设计外文翻译(Thesis Translation)是指在毕业设计过程中,对相关外文文献进行翻译,并将其应用于研究中,以提供理论支持和参考。
1 工程概论1.1 工程专业1.2 工业和技术1.3 现代制造业工程专业1 工程行业是历史上最古老的行业之一。
如果没有在广阔工程领域中应用的那些技术,我们现在的文明绝不会前进。
第一位把岩石凿削成箭和矛的工具匠是现代机械工程师的鼻祖。
那些发现地球上的金属并找到冶炼和使用金属的方法的工匠们是采矿和冶金工程师的先祖。
那些发明了灌溉系统并建造了远古世纪非凡的建筑物的技师是他们那个时代的土木工程师。
2 工程一般被定义为理论科学的实际应用,例如物理和数学。
许多早期的工程设计分支不是基于科学而是经验信息,这些经验信息取决于观察和经历,而不是理论知识。
这是一个倾斜面实际应用的例子,虽然这个概念没有被确切的理解,但是它可以被量化或者数字化的表达出来。
3 从16、17世纪当代初期,量化就已经成为科学知识大爆炸的首要原因之一。
另外一个重要因素是实验法验证理论的发展。
量化包含了把来源于实验的数据和信息转变成确切的数学术语。
这更加强调了数学是现代工程学的语言。
4 从19世纪开始,它的结果的实际而科学的应用已经逐步上升。
机械工程师现在有精确的能力去计算来源于许多不同机构之间错综复杂的相互作用的机械优势。
他拥有能一起工作的既新型又强硬的材料和巨大的新能源。
工业革命开始于使用水和蒸汽一起工作。
从此使用电、汽油和其他能源作动力的机器变得如此广泛以至于它们承担了世界上很大比例的工作。
5 科学知识迅速膨胀的结果之一就是科学和工程专业的数量的增加。
到19世纪末不仅机械、土木、矿业、冶金工程被建立而且更新的化学和电气工程专业出现了。
这种膨胀现象一直持续到现在。
我们现在拥有了核能、石油、航天航空空间以及电气工程等。
每种工程领域之内都有细分。
6 例如,土木工程自身领域之内有如下细分:涉及永久性结构的建筑工程、涉及水或其他液体流动与控制系统的水利工程、涉及供水、净化、排水系统的研究的环境工程。
机械工程主要的细分是工业工程,它涉及的是错综复杂的机械系统,这些系统是工业上的,而非单独的机器。
机械设计毕业设计外文文献翻译中英文对照:塑料模具CAD集成技术毕业设计外文文献翻译毕业设计题目摇控器面板注塑模设计翻译题目The molding tool CAD gathers the technique专业机械设计制造及其自动化姓名班级机械A0731学号指导教师机械与材料工程学院二O一O年十一月[K.P. Rao and K. Sivaram: J. Mater. Proc. Technol., 1993, vol. 37, pp.295-318.]毕业论文(设计)外文翻译课题名称:塑料模具CAD集成技术内容提要:通过分析计算机辅助注射模设计和制造的各个环节中共享的技术和信息,本文揭示了注射模CAD的集成技术的根本内涵,并提出了它的研究热点和趋势。
引言模具CAD集成技术是一项重要的模具先进制造技术, 是一项用高技术改造模具传统技术的重要关键技术。
从六五计划开始,我国有许多模具企业采用CAD 技术, 特别是近年, CAD技术的应用越来越普遍和深入, 大大缩短了模具设计周期,提高了制模质量和复杂模具的制造能力。
然而, 由于许多企业对模具CAD集成技术认识不足, 投资带有盲目性, 不能很好地发挥作用,造成了很大的浪费。
本文就塑料模具CAD集成技术及其应用发表一些观点, 供大家参考。
1、塑料模具CAD集成技术塑料模具的制造, 包括塑料产品的造型设计、模具的结构设计及分析、模具的数控加工铣削、电加工、线切割等、抛光和配试模以及快速成形制造等。
各个环节所涉及的CAD单元技术有:造型和结构设计CAD、产品外形的快速反求RE、结构分析与优化设计CAE、辅助制造CAM、加工过程虚拟仿真SIMULATION、产品及模具的快速成形RP、辅助工艺过程CAPP和产品数据管理技术PDM等。
塑料模具CAD集成技术,? 就是把塑料模具制造过程所涉及的各项单元技术集成起来, 统一数据库和文件传输格式, 实现信息集成和数据资源共享, 从而大大缩短模具的设计制造周期, 提高制模质量。
毕业设计(论文)外文资料翻译及原文(2012届)题目电话机三维造型与注塑模具设计指导教师院系工学院班级学号姓名二〇一一年十二月六日【译文一】塑料注塑模具并行设计Assist.Prof.Dr. A. Y AYLA /Prof.Dr. Paş a YAYLA摘要塑料制品制造业近年迅速成长。
其中最受欢迎的制作过程是注塑塑料零件。
注塑模具的设计对产品质量和效率的产品加工非常重要。
模具公司想保持竞争优势,就必须缩短模具设计和制造的周期。
模具是工业的一个重要支持行业,在产品开发过程中作为一个重要产品设计师和制造商之间的联系。
产品开发经历了从传统的串行开发设计制造到有组织的并行设计和制造过程中,被认为是在非常早期的阶段的设计。
并行工程的概念(CE)不再是新的,但它仍然是适用于当今的相关环境。
团队合作精神、管理参与、总体设计过程和整合IT工具仍然是并行工程的本质。
CE过程的应用设计的注射过程包括同时考虑塑件设计、模具设计和注塑成型机的选择、生产调度和成本中尽快设计阶段。
介绍了注射模具的基本结构设计。
在该系统的基础上,模具设计公司分析注塑模具设计过程。
该注射模设计系统包括模具设计过程及模具知识管理。
最后的原则概述了塑料注射模并行工程过程并对其原理应用到设计。
关键词:塑料注射模设计、并行工程、计算机辅助工程、成型条件、塑料注塑、流动模拟1、简介注塑模具总是昂贵的,不幸的是没有模具就不可能生产模具制品。
每一个模具制造商都有他/她自己的方法来设计模具,有许多不同的设计与建造模具。
当然最关键的参数之一,要考虑到模具设计阶段是大量的计算、注射的方法,浇注的的方法、研究注射成型机容量和特点。
模具的成本、模具的质量和制件质量是分不开的在针对今天的计算机辅助充型模拟软件包能准确地预测任何部分充填模式环境中。
这允许快速模拟实习,帮助找到模具的最佳位置。
工程师可以在电脑上执行成型试验前完成零件设计。
工程师可以预测过程系统设计和加工窗口,并能获得信息累积所带来的影响,如部分过程变量影响性能、成本、外观等。
附录1 英文原文The molding tool CAD gathers the techniqueContents brief summary: Pass to analyze the calculator the assistance inject the mold design with make in the each link commonly shared of technique with information, this text announces to public to inject the mold CAD gathers technical and basic content, and the research heat that put forward it orders with trend.0, prefaceThe molding tool CAD gathers the technique is an important molding tool forerunner manufacturing technique, is the item reforms with the high technique traditional technical and important key in molding tool technique. From 6 5 plan beginning,Our country contain many molding tools business enterprise adoption CAD technique, especially recent years, the technical application in CAD is more and more widespread with thorough, shortened consumedly molding tool design period, Increases to make the mold quantity with the manufacturing ability that complicated molding tool.However, gather to the molding tool CAD because of many business enterprises technique cognition shortage, investment take the blindness, can't produce result nicely,Result in very big and wasted.This text gathers for the plastics molding tool CAD technique and its applications announce some standpoint, provide everybody consults.1, the plastics molding tool CAD gathers techniqueThe manufacturing of the plastics molding tool comtains the construction design of the shape design, molding tool and the number of the analysis, molding tools that include the plastics products control to process( I I , electricity process, the line incises etc.), throw the light with go together with to try the mold and take shape manufacturing etc. quickly.The each link a CAD for involving unit technique has: The shape design( CAD) with the construction, fast anti of the product shapebeg( RE), construction analysis with excellent turn the design( CAE), lend support to the manufacturing( CAM) and process the process conjecture imitate true( SIMULATION), product and molding tools take shape( RP) quickly, assistance craft process( CAPP) with product data management technique( PDM) etc..The plastics molding tool CAD gathers technique,Is to gather plastics molding tool manufacturing process a various units for involving technique get up, unify the database to deliver the format with the document, realize the information gather share with the data resources, from but shorten the design manufacturing period of the molding tool consumedly,Increases to make the mold quantity.2, the CAD design of the plastics product begs with fast anti of the shapeThe plastics molding tool that proceed the square one designs the manufacturing is the design of the EU a product.The traditional product design method is a design to product of three is conceive outline to use two I plane chart papers expresses to come out, marking clearly the craft and starting construction the method on the diagram paper,This kind of met hod comes to a decision the simple of a design sketch and can''ts control to make the quantity directly.The modern design method is a design establish the product directly on the computer of three the model of I ,According to the product three I models proceed the molding tool construction the design and excellent turn the design,Design according to the molding tool construction again three I models proceed to process to weave the distance and establishment crafts plan.This kind of method makes product model design, molding tool construction design, process to weave distance and technological designs regard a data as the foundation, realizing the data share, Can not only increases to design the efficiency quickly, but also can guarantee the quantity, decline low cost.The source of the computer EU a product model has three kinds of:Making use of the CAD system software proceeds the product model the designand make use of the real object measures fast anti in proceeding beg to set up the mold and make use of the standard format document of the other the system of CAD.Source method that aim at these three kinds of products model,Have studied every kind of technique now to the design efficiency that increases product model with quantity.The underneath further analyzes every kind of technical content with the characteristics.Making use of the CAD system software proceeds the product model design,Its technique includes primarily two is are several why the sketch draws, two the parameter of is turn the design of the sketch, three i entity shape design, three icharacteristic shape design, three the parameter of is turn the entity shape the design, three i curved face shape design, free shape in space design, the external appearance of the product exaggerates, product of dynamic advertise to design the etc..These softwareses contain many typical representatives.Two the software of is have: ME10, CADKEY, AUTOCAD, DHCAD, Genis, etc. of Sigraph; three the software of is have:UGII, PRO/ E, IDEAS, CATIA, etc. of EUCLID; free shape in product and advertise the software of the design have:Alias, etc. of CDRS.Two is are several why the sketch draws is to make use of the flat surface CAD software draw the spare parts sketch, then replace the handicraft painting with the calculator; but two the parameter of is turn,Then the calculator realizes the sketch changes the deal designs, making modification more convenient; threeishape designs is a true shape that the product that the arithmetic figure turn design, it expressed completely product,Can be further to designs for the molding tool, analysis with processes the mathematics model of the necessity of offering; the free shape in space design is the art of the product shape to design, making product been not only is a function product, but also art article.It is every kind of need that the external appearance of the product exaggerate that product of the result designs, making product more beautiful, the color can attractpeople more; the dynamic advertisement design of the product is a result that design to make to promote the advertisement directly the product,Proceed the market expansion.Making use of the real object measures fast anti of proceeding beg to set up mold is current investigative a little bit hot of a,It is an important technique that product imitate the type foundation go forward a line of the product modification designs.Its basic principle is to passes three coordinateses measure the machine, laser measure machine or electronicses copy the few ÒÇ to proceed to scan the diagraph to the real object,The data of large quantity that arithmetic figure turn that gets to measures the acquisition orders anti that send into the high class CAD software beg mold piece or appropriative anti beg the software inside, anti beg the software can read directly a data cluster,Combining can proceed the editor, filter, tidy up, beg the ¾« to a data cluster, row preface, part modification and reorganization, then automatic born curved face, It is end to acquire together the real object precision is consistent of or computer EU a product model that pass through reforms.This way can increases biggest new product design velocity.Current mature curved face anti beg to set up the mold software has: Surfacer,Cimatronrenge, etc. of Strim100.Make use of the standard format document of the other the system of CAD to set up the mold, this way than convenience.Because the world of the market turns with the technical development in the network of INTERNET,The CAD technique exchanges of the molding tool business enterprise with cooperate to have many pass the CAD document method proceed.Because the CAD system category is more, therefore documentary format must follow the international standard,Such as the DXF, IGES, STEP, VDA, etc. of STL.Pass to read standard format document to establish directly or establish the product model after modifying, since canquickly, deepen the customer and the exchanges of the molding tool factory house, Also can shorten the product the design the period.3, the CAD design of the molding tool and analysisThe CAD design of the molding tool, analysis,Include to divide the type, certain type C» according to the product model molding tool of proceeding the design with the type D¾ , molding tool structural and detailed design, the plastics ³a fills process analysis etc. a few aspects.Make use of the advanced characteristic shape software,such as PRO/ E, etc. of UGII, the very easily certain dividing the type,Born top and bottom mold C» with mold D¾, then the proceeding flows a way, sprinkle a people and cool off the pipe line of arrange etc..Made sure these designses data hereafter, then make use of the molding tool analysis software,Proceed such as the MOLDFLOW, CFLOW the plastics take shape the process analysis.According to the software of MOLDFOLW with it of the material, craft database of plentifulness, pass the importation take shape the craft parameter,Can the development imitate the true analysis plastics to inject in note EU mold C» the process flows the circumstance( the plastics with sprinkle a people more inject remits to flow the analysis of ÎAE ), analyze the temperature pressure variety circumstance and analyze to note EU a ²D remaining should dint etc.,According to analyze the circumstance to the rationality that check the molding tool construction, flow quantity problem etc. of the rationality, product of the appearance.For example whether the esse sprinkles to note the system not reasonable, appear to flow way with sprinkle a position size not appropriate,Can''t equilibrium alive with type C» ; whether to exsit product construction absurdity or molding tool constructions or not is not reasonable, appearing the product A dissatisfied( namely short shoot the phenomenon); whether to cool off asymmetry or not, the influence produces the efficiency with product quantity;Whether the esse notes the craft of EU wrong, appear the song of CI of the product transform etc..The molding tool passes the CAD the design with analyze, can dissolvemistake at design the stage, increase to try once the mold the success the rate.At plastics molding tool design with analyze to apply many new computer.aideds technique this stage, if the parameter turns technique, characteristic shape technique, database technique etc..There is many standards piece in the plastics molding tool, Turn such as the standard mold a parameter for outing organization, sprinkling noting system, cooling system...etc. can adopting basing on database managing the characteristic shape design method proceed the design or establish the standard a a, like this since can realize the data share,Can satisfy the customer again to the at any time modifying of the design, make the design analysis of the molding tool fast, accurate, efficiently.The parameter turns the characteristic shape can not only describe the product completely then several why sketch information,And can acquire accuracy, material and assemble etc. informations of the product, its a product for establishing model is a kind of apting to handle and can reflect design intention with process the model of the characteristic.Therefore,The parameter turns the characteristic shape technique is an one of the most important technique in process in manufacturing in molding tools.4, the technical application in CAM of the molding tool, process to imitate true and ml;I processing, line incising to process, electricity spark processing to wait.The technique of CAM rises in the type C» , type D¾ of the complicated molding tool and the I I of the electrodes process particularly more important function.Its main technique characteristics includes:(1) the O , ¾« processes the knife have the track excellent to turn the programming with the instruction of NC creation,(2) the knife has the category, characteristic to establish with the material ,(3) slicing the Ï÷ process the craft parameter to really settle,(4)The commonness slices the Ï÷ to slice with the high speed the characteristic that I process controls,(5) over slice the check with process the superficial accuracy control,(6)processing the computer entity of the process imitate the realistic I ,(7) The computer control number controls the technique of DNC and clusters of the machine bed control the technical and applied etc..Need the CAD specially in technical application in CAM three I product model data.More profession computer plait distance software,such as MASTERCAM, UNIMOD, etc. of CIMATRON, when the plait distance of many curved faces processes have the higher request to the curved face model of the product,Intend with the high accuracy of the curved face to match such as the directional consistency, curved face in U, V of the close together curved face, inclined rate in curved face continuous variety etc..In high class CAD/ the integral whole of CAM turn system,( such as UGII, PRO/ E)Because making use of the parameter turns the characteristic shape design with same database technique, making the type C of the product model data, molding tool have the track data to have got the inside contact with the type D¾ model data, knife, The modification knife of the product model has the track to also modify automatically.The molding tool processes the entity imitates the true technique more and more mature, also is more and more valued by people.It is mimicry machine bed that processing the entity imitate process the process on the computer, can keep the result that view reflect process,Can takes the gauge of directly quantity that after processing spare parts, can check the mistake that process.At check quantity that after processing spare parts, can at the computer is last to process behind of the entity model proceeds the aleatoric EE slices, Measure its size directly with the accuracy.Therefore, it can dissolve mistake at process the stage of craft plait distance design, reduce to repair after processing with return the work, increases consumedly the manufacturing efficiency of the molding tool with quantity.5, plastics product and its molding tools take shape the manufacturing quicklyPlastics product and its molding tools use the computer CAD techniquewdesignafter completing, can pass the fleetness take shape the technique make.This is the manufacturing technique of a kind of all new concept,It abandoned the traditional machine processes the method.Its take shape principle is three I CAD entity models are long.lost set up a series of a layer data of the thickness, make use of the laser take shape machine or others take shape the equipments read these datas,Increase the method technique with the material, pile up the each layer to take shape one by one in order.This technique calls the fleetness to take shape the technique automatically.( Rapid Prototype)It is also a CAD to gather the technical importance constitutes the part.The first pedestal takes shape the equipments quickly to bear in the United States a company in 1987, because of its characteristics is to has nothing to do with the complicated degree of the product of the manufacturing, bringing the manufacturing industry the enormous vibration.Henceforth decade,Take shape quickly the technique be flown to develop soon, the category of the equipments also piles up one after another,Turn from the material I the method can is divided into the laser with not the laser burns the knot method( SLS), solid surface layer shape method( SGC), layer a manufacturing method( LOM) and melt to sink to accumulate the method( FDM), district constituency glues the knot method( DSPC), laser spirit to sink to accumulate method( SALD) etc. mutually.Every kind of method characteristics is:The method of SLA is applied at the earliest stage of took shape the technique quickly, the early market occupied the bigger cent sum, but is narrow because of the material scope, the cost is higher, taking shape the piece was heat.proof and bore the burthen with applied color the ability low,The recent years was gradually replaced by the other method.The method of FDM because of taking shape the speed quick, the cost is low, get the good application in plastics product profession, because the size of the spare parts is small, accuracy bad, Also suffer certainly of restrict.The method of LOM because of adoption paper or isoutline edge that thin slice plastics, the cost is low, and the laser projects light upon each layer only, as a result take shape the speed quick,But the product surface quantity is bad.The method of SLS proceeds to burn the knot with the laser, adoptive material than wide, if the plastics,A¯ anticipates, porcelain and ceramics, metals etc. all can take shape, taking shape the piece is heat.proof and bear the burthen with apply color the ability stronger,Have the extensive and applied foreground.The other method also gets the application in some special kinds process.According to above take shape the method characteristics, take shape the technical function quickly to consist in primarily:The manufacturing useds for the design with the on trial product model, make to used for the small the molding tool that batch quantity produce to process with the special spare parts in small batch quantity.Take shape the product model of the technique manufacturing quickly in the aspects of material the ratio tradition processes the product model of the method manufacturing has the difference,But in shape and sizes almost complete similar, and there is certain machine strength, can make the function experiment, handles through surface at the same time, looking similar to true product,Can advertise the propaganda material.Take shape the molding tool of the technique manufacturing quickly,Is a soft material to take shape the mold( the mold of A¯ , wreath oxygen resin mold, ¹è rubber mold, low EU orders the metal alloy casts mold etc.) primarily to synthesize the hard type in material C mold with porcelain and ceramics or metals »ùs now.Hard mold in manufacturing the hour can take shape with the fleetness the spare parts makes the female die,Create first the soft mold between wreath oxygen resin mold or other material, sprinkle to note porcelain and ceramics or gypsum molds in soft mold, then sprinkle the steel of Öý steel mold; or sprinkle the admixture that note in soft mold chemistry contain steel powder glue knot,Proceed to burn to become the steel mold.Take shape the steel mold of the technique manufacturing quickly to process after needing further did to throw light etc., make into the small batch quantity produce of note the mold of EU .Because the molding tool sprinkles to note or burn the knot with the steel powder but, Material and common molding tool steel contain certain margin, therefore, the life span is shorter, cans make to manufacture on a trial basis product or small batch quantities produce.Moreover, taking shape the technique quickly can also manufacture the special spare parts,If make with the metallurgy powder legal system the metals electrode, nicety cast the legal system makes the copper electrode, ND mold legal system makes graphite electrode etc..Take shape the technique creation molding tool quickly to model the equipments with the product, all is STL to read CAD system creation or CLI etc. document format datas,Different document format data to the product accuracy of the creation contain bigger margin, therefore, study the system of CAD to take shape quickly the document format of the equipments output to have the very important meaning.6, the molding tool CAD gathers technical development trendA calculator for saying, molding tool CAD gathering technique is applying in molding tool making each link assistance technique on the ×U with each link information that realizes the technique gathers.Obviously,The information gathers unify with data the management is a key.The information of the product is to pierces through in the design, analyze, process, examine, assemble a stage,Fluency, solution data format that realizes each link information standardizes and the data maintenance is a point with future CAD that share to gather technique development.The system of PDM emergence is to resolve this problem brought the first light of day.It is molding tool business enterprise application CAD that the system of PDM puts into practice gather technical and important lesson.Design in molding toolmanufacturing aspect,The intelligence that imply the research, high speed that abundant expert''s knowledge turn molding tool CAD/ the system of CAM slices theI÷ processes and its plait distance etc. is a trend that future study the development.2 中文翻译塑料模具CAD集成技术内容提要:通过分析计算机辅助注射模设计和制造的各个环节中共享的技术和信息,本文揭示了注射模CAD的集成技术的根本内涵,并提出了它的研究热点和趋势。
华南理工大学广州学院本科生毕业设计(论文)翻译英文原文名Review of Vibration Analysis Methods for Gearbox Diagnostics and Prognostics中文译名对变速箱振动分析的诊断和预测方法综述学院汽车工程学院专业班级车辆工程七班学生姓名刘嘉先学生学号201130085184指导教师李利平填写日期2015年3月15日英文原文版出处:Proceedings of the 54th Meeting of the Society for Machinery Failure Prevention Technology, Virginia Beach,V A, May 1-4,2000,p. 623-634译文成绩:指导教师(导师组长)签名:译文:简介特征提取技术在文献中有描述;然而,大多数人似乎掩盖所需的特定的预处理功能。
一些文件没有提供足够的细节重现他们的结果,并没有一个全面的比较传统的功能过渡齿轮箱数据。
常用术语,如“残差信号”,是指在不同的文件不同的技术.试图定义了状态维修社区中的常用术语和建立所需的特定的预处理加工特性。
本文的重点是对所使用的齿轮故障检测功能。
功能分为五个不同的组基于预处理的需要。
论文的第一部分将提供预处理流程的概述和其中每个特性计算的处理方案。
在下一节中,为特征提取技术描述,将更详细地讨论每一个功能。
最后一节将简要概述的宾夕法尼亚州立大学陆军研究实验室的CBM工具箱用于齿轮故障诊断。
特征提取概述许多类型的缺陷或损伤会增加机械振动水平。
这些振动水平,然后由加速度转换为电信号进行数据测量。
原则上,关于受监视的计算机的健康的信息被包含在这个振动签名。
因此,新的或当前振动签名可以与以前的签名进行比较,以确定该元件是否正常行为或显示故障的迹象。
在实践中,这种比较是不能奏效的。
由于大的变型中,签名的直接比较是困难的。
相反,一个涉及从所述振动署名数据特征提取更多有用的技术也可以使用。
附录A冲压中多工件的最佳排样摘要:在冲压生产中,生产成本受材料利用率影响最大,材料支出占整个生产成本的75%。
本文将介绍一种新的计算方法用于实现双工件在冲压排样设计中的最佳规划方法,以便提高材料利用率。
这种计算方法可以预示在带料中结构废料的位置及形状,以及工艺废料的位置和最佳宽度。
例如将两个相同的工件中的其中一个旋转180°,或是将两个不同的工件嵌套在一起。
这种计算方法适合与冲模设计CAE系统结合使用。
关键字:冲压,模具设计,最佳化,材料利用率,明可夫斯基和,设计工具绪论在冲压生产中,能够快速生产不同复杂程度的薄片金属零件,特别是在大产量的情况下,能够高强度生产。
生产过程效率高,其中材料成本占据整个冲压生产成本的75% [1]。
但材料不能被完全利用到零件上,因为零件不规则的外形必须被包含在带料内。
冲压生产的排样设计直接决定废料的大小。
很明显,使用最理想的排样设计对于提高公司的竞争力是至关重要的。
前期工作曾经, 带料排样设计问题需要通过手工来解决。
例如, 通过纸板模拟冲裁来获取一个好的排样方法。
通过计算机介绍的设计过程所得出的步骤。
也许首先要做出适合工件的矩形,然后将矩形顺序排放在带料上[2]。
这种方法适合不相互重叠的矩形[3]、拉深多边形[4, 5]、已知相互关联的外形[6]。
这种原理的方法具有一定局限性,尽管如此,在这种具有局限性下的设计中所产生较多的工艺废料不能被避免,这些额外损失的材料导致了设计方案无法达到最佳化。
增量旋转法是一种流行的排样设计方法[6-10, 16]。
具体实现方法为,将零件旋转一定的角度,例如2°,[7],在设计中决定零件倾斜程度和带料宽度以及合适的材料利用率。
在不断重复这些步骤以后工件旋转量达到180º (由于对称),然后从中选出最佳排样方法。
这种方法的缺点是,在一般情况下,最佳材料定位将降低旋转增量同时不能被找到。
尽管差别很小,但在大批量生产中每个零件所浪费的材料会累计进而导致较多材料损失。
毕业设计外文资料翻译学院:信息科学与工程学院专业:软件工程姓名: XXXXX学号: XXXXXXXXX外文出处: Think In Java (用外文写)附件: 1.外文资料翻译译文;2.外文原文。
附件1:外文资料翻译译文网络编程历史上的网络编程都倾向于困难、复杂,而且极易出错。
程序员必须掌握与网络有关的大量细节,有时甚至要对硬件有深刻的认识。
一般地,我们需要理解连网协议中不同的“层”(Layer)。
而且对于每个连网库,一般都包含了数量众多的函数,分别涉及信息块的连接、打包和拆包;这些块的来回运输;以及握手等等。
这是一项令人痛苦的工作。
但是,连网本身的概念并不是很难。
我们想获得位于其他地方某台机器上的信息,并把它们移到这儿;或者相反。
这与读写文件非常相似,只是文件存在于远程机器上,而且远程机器有权决定如何处理我们请求或者发送的数据。
Java最出色的一个地方就是它的“无痛苦连网”概念。
有关连网的基层细节已被尽可能地提取出去,并隐藏在JVM以及Java的本机安装系统里进行控制。
我们使用的编程模型是一个文件的模型;事实上,网络连接(一个“套接字”)已被封装到系统对象里,所以可象对其他数据流那样采用同样的方法调用。
除此以外,在我们处理另一个连网问题——同时控制多个网络连接——的时候,Java内建的多线程机制也是十分方便的。
本章将用一系列易懂的例子解释Java的连网支持。
15.1 机器的标识当然,为了分辨来自别处的一台机器,以及为了保证自己连接的是希望的那台机器,必须有一种机制能独一无二地标识出网络内的每台机器。
早期网络只解决了如何在本地网络环境中为机器提供唯一的名字。
但Java面向的是整个因特网,这要求用一种机制对来自世界各地的机器进行标识。
为达到这个目的,我们采用了IP(互联网地址)的概念。
IP以两种形式存在着:(1) 大家最熟悉的DNS(域名服务)形式。
我自己的域名是。
所以假定我在自己的域内有一台名为Opus的计算机,它的域名就可以是。
毕业设计(论文)外文资料翻译学院:机械工程专业:机械设计制造及其自动化姓名:学号:3082108330外文出处:Lecture Notes in Computer science (用外文写)附件: 1.外文资料翻译译文;2.外文原文。
注:请将该封面与附件装订成册。
附件1:外文资料翻译译文高速加工和现代模具制造一、概述1 目前模具制造的发展现状和趋势模具作为重要的工艺装备,在消费品、电器电子、汽车、飞机制造等工业部门中,占有举足轻重的地位。
工业产品零件粗加工的75%,精加工的50%及塑料零件的90%将由模具完成。
目前中国模具市场需求已达500亿元之规模。
汽车模具、特别是覆盖件模具年增长速度将超过20%;建材模具也迅速发展,各种异型材模具、墙面和地面模具成为模具的新增长点,今后几年塑料门窗和塑料排水管增长将超过30%;家电模具年增长速度将超过10%;IT业年均增长速度超过20%,对模具的需求占模具市场的20%。
2004年中国机床工具工业产值将继续增长。
我国模具制造市场潜力巨大。
根据资料统计,近年来,我国模具的年总产值达到30亿美元,进口超过10亿美元,出口超过1亿美元。
增长从1995年的25%增加到2005年的50%。
国外专家预言:亚洲在全球模具制造中占据的份额,将从1995年的25%增加至2005年的50%。
中国模具工业发展迅速,形成了华东和华南两人基地,并且逐渐扩大到其他省份。
(山东,安徽,四川) 1996年~2002年,模具制造业产值年平均增长14%, 2003年增长25%。
2003年我国模具产值为450亿人民币总产量位居世界第3,出口模具3.368亿美元,比上年增长33.5%。
但是,我国技术含量低的模具已供过于求,精密、复杂的高档模具很大部分依靠进口。
每年进口模具超过10亿美元。
出口超过1亿美元,精密模具精度要求在2~3u m,大型模具需要满足8000kN合模力注塑机的要求;小型模具需满足直径1mm 塑料管的要求。
外文翻译原文:Injection MoldingMany different processes are used to transform plastic granules, powders, and liquids into product. The plastic material is in moldable form, and is adaptable to various forming methods. In most cases thermosetting materials require other methods of forming. This is recognized by the fact that thermoplastics are usually heated to a soft state and then reshaped before cooling. Theromosets, on the other hand have not yet been polymerized before processing, and the chemical reaction takes place during the process, usually through heat, a catalyst, or pressure. It is important to remember this concept while studying the plastics manufacturing processes and polymers used.Injection molding is by far the most widely used process of forming thermoplastic materials. It is also one of the oldest. Currently injection molding accounts for 30% of all plastics resin consumption. Since raw material can be converted by a single procedure, injection molding is suitable for mass production of plastics articles and automated one-step production of complex geometries. In most cases, finishing is not necessary. Typical products include toys, automotive parts, household articles, and consumer electronics goods.Since injection molding has a number of interdependent variables, it is a process of considerable complexity. The success of the injection molding operation is dependent not only in the proper setup of the machine hydraulics, barrel temperature variations, and changes in material viscosity. Increasing shot-to-shot repeatability of machine variables helps produce parts with tighter tolerance, lowers the level of rejects, and increases product quality (i.e., appearance and serviceability).The principal objective of any molding operation is the manufacture of products: to a specific quality level, in the shortest time, and using repeatable and fully automatic cycle. Molders strive to reduce or eliminate rejected parts in molding production.For injection molding of high precision optical parts, or parts with a high added value such as appliance cases, the payoff of reduced rejects is high.A typical injection molding cycle or sequence consists of five phases;1. Injection or mold filling2. Packing or compression3. Holding4. Cooling5. Part ejectionPlastic granules are fed into the hopper and through an in the injection cylinder where they are carried forward by the rotating screw. The rotation of the screw forces the granules under high pressure against the heated walls of the cylinder causing them to melt. As the pressure building up, the rotating screw is forced backward until enough plastic has accumulated to make the shot. The injection ram (or screw) forces molten plastic from the barrel, through the nozzle, sprue and runner system, and finally into the mold cavities. During injection, the mold cavity is filled volumetrically. When the plastic contacts the cold mold surfaces, it solidifies (freezes) rapidly to produce the skin layer. Since the core remains in the molten state, plastic follows through the core to complete mold filling. Typically, the cavity is filled to 95%~98% during injection. Then the molding process is switched over to the packing phase.Even as the cavity is filled, the molten plastic begins to cool. Since the cooling plastic contracts or shrinks, it gives rise to defects such as sink marks, voids, and dimensional instabilities. To compensate for shrinkage, addition plastic is forced into the cavity. Once the cavity is packed, pressure applied to the melt prevents molten plastic inside the cavity from back flowing out through the gate. The pressure must be applied until the gate solidifies. The process can be divided into two steps (packing and holding) or may be encompassed in one step(holding or second stage). During packing, melt forced into the cavity by the packing pressure compensates for shrinkage. With holding, the pressure merely prevents back flow of the polymer malt.After the holding stage is completed, the cooling phase starts. During, the part is held in the mold for specified period. The duration of the cooling phase depends primarily on the material properties and the part thickness. Typically, the part temperature must cool below the material’s ejection temperature. While cooling the part, the machine plasticates melt for the next cycle.The polymer is subjected to shearing action as well as the condition of the energy from the heater bands. Once the short is made, plastication ceases. This should occur immediately before the end of the cooling phase. Then the mold opens and the part is ejected.When polymers are fabricated into useful articles they are referred to as plastics, rubbers, and fibers. Some polymers, for example, cotton and wool, occur naturally, but the great majority of commercial products are synthetic in origin. A list of the names of the better known materials would include Bakelite, Dacron, Nylon, Celanese, Orlon, and Styron.Previous to 1930 the use of synthetic polymers was not widespread. However, they should not be classified as new materials for many of them were known in the latter half of the nineteenth century. The failure to develop them during this period was due, in part, to a lack of understanding of their properties, in particular, the problem of the structure of polymers was the subject of much fruitless controversy.Two events of the twentieth century catapulted polymers into a position of worldwide importance. The first of these was the successful commercial production of the plastic now known as Bakelite. Its industrial usefulness was demonstrated in1912 and in the next succeeding years. Today Bakelite is high on the list of important synthetic products. Before 1912 materials made from cellulose were available, but their manufacture never provided the incentive for new work in the polymer field such as occurred after the advent of Bakelite. The second event was concerned with fundamental studies of the nature polymers by Staudinger in Europe and by Carohers, who worked with the Du Pont company in Delaware. A greater part of the studies were made during the 1920’s. Staudinger’s work was primarily fundamental. Carother’s achievements led to the development of our present huge plastics industry by causing an awakening of interest in polymer chemistry, an interest which is still strongly apparent today.The Nature of ThermodynamicsThermodynamics is one of the most important areas of engineering science used to explain how most things work, why some things do not the way that they were intended, and why others things just cannot possibly work at all. It is a key part of the science engineers use to design automotive engines, heat pumps, rocket motors, power stations, gas turbines, air conditioners, super-conducting transmission lines, solar heating systems, etc.Thermodynamics centers about the notions of energy, the idea that energy is conserved is the first low of thermodynamics. It is starting point for the science of thermodynamics is entropy; entropy provides a means for determining if a process is possible.This idea is the basis for the second low of thermodynamics. It also provides the basis for an engineering analysis in which one calculates the maximum amount of useful that can be obtained from a given energy source, or the minimum amount of power input required to do a certain task.A clear understanding of the ideas of entropy is essential for one who needs to use thermodynamics in engineering analysis. Scientists are interested in using thermodynamics to predict and relate the properties of matter; engineers are interested in using this data, together with the basic ideas of energy conservation and entropy production, to analyze the behavior of complex technological systems.There is an example of the sort of system of interest to engineers, a large central power stations. In this particular plant the energy source is petroleum in one of several forms, or sometimes natural gas, and the plant is to convert as much of this energy as possible to electric energy and to send this energy down the transmission line.Simply expressed, the plant does this by boiling water and using the steam to turn a turbine which turns an electric generator.The simplest such power plants are able to convert only about 25 percent of the fuel energy to electric energy. But this particular plant converts approximately 40 percent;it has been ingeniously designed through careful application of the basic principles of thermodynamics to the hundreds of components in the system.The design engineers who made these calculations used data on the properties of steam developed by physical chemists who in turn used experimental measurements in concert with thermodynamics theory to develop the property data.Plants presently being studied could convert as much as 55 percent of the fuel energy to electric energy, if they indeed perform as predicted by thermodynamics analysis.The rule that the spontaneous flow of heat is always from hotter to cooler objects is a new physical idea. There is noting in the energy conservation principle or in any other law of nature that specifies for us the direction of heat flow. If energy were to flow spontaneously from a block of ice to a surrounding volume of water, this could occur in complete accord with energy conservation. But such a process never happens. This idea is the substance of the second law of thermodynamics.Clear, a refrigerator, which is a physical system used in kitchen refrigerators, freezers, and air-conditioning units must obey not only the first law (energy conservation) but the second law as well.To see why the second law is not violated by a refrigerator, we must be careful in our statement of law. The second law of thermodynamics says, in effect, that heat never flows spontaneously from a cooler to a hotter object.Or, alternatively, heat can flow from a cooler to a hotter object only as a result of work done by an external agency. We now see the distinction between an everyday spontaneous process, such as the flow of heat from the inside to the outside of a refrigerator.In the water-ice system, the exchange of energy takes place spontaneously and the flow of heat always proceeds from the water to the ice. The water gives up energy and becomes cooler while the ice receives energy and melts.In a refrigerator, on the other hand, the exchange of energy is not spontaneous. Work provided by an external agency is necessary to reverse the natural flow of heat and cool the interior at the expense of further heating the warmer surroundings.译文:塑料注射成型许多不同的加工过程习惯于把塑料颗粒、粉末和液体转化成最终产品。