增材制造技术发展和在先进轨道交通装备中的应用展望

从增材制造技术的应用现状出发,概述了几种增材制造技术的特点和应用范围;介绍了典型的金属增材制造最新研究进展;考虑现有增材制件存在的固有缺陷、残余应力和裂纹等问题,总结了能有效改善成形增材制件质量的后处理工序;梳理了增材制件疲劳性能的影响因素,重点阐述了缺陷与增材制件疲劳损伤的关联性;探讨了增材制造技术广泛应用所涉及的关...     

Multi-scale simulation for the forming of a heavy vessel head considering the evolution of defects and microstructure

The head of nuclear pressure vessel is a key component to guarantee the safety of nuclear power plant, so it is necessary to improve its mechanical properties during manufacturing. In the practical production, due to the huge size of the ingots from which the head is manufactured, coarse grains and voids are common defects existing in the material. Furthermore, cracks may appear in the forming process. It is highly demanded that the forming process must be properly designed with suitable parameters to compact the voids, to refine and homogenize the grains and to avoid cracks. Therefore, the research on the evolution of internal voids, grain size and cracks is very important to determine the forming process of huge components. SA508-3 steel is the material to manufacture the head of pressure vessel in the nuclear island. In the previous studies, we have separately built models to evaluate the evolution of internal voids, grain size and cracks during the hot forming process for SA508-3 steel. This study integrates the models for multi-scale simulation of the forging process of the head of nuclear pressure vessel in order to control the quality of the forgings. Through the software development, the models are integrated with a commercial finite element code DEFORM. Then, the extended forging and final forging processes of the head are investigated, and some appropriate deformation parameters are recommended.     

Computer Aided Simulation on Precision Cold Forging of Universal Joint Cross

IntroductionThefiwtee1emenmethod(FEM)playsanextrmelyimPortantroleintheanalysesofengineeringproblems.ForalongtimethismethodhasmainlybeenaPPliedinthelinearfieldandshownitsgreatpower.HoweveealOtofnonlinearengineeringPrOblemsWhichcanneitherbesimPlyreducedtolinearonesnorrCPresentedbylinearlyanalogywhichshallchnsethePfacticalconditionsrelativelymuch,havechallengedfiniteelementmethod(FEM).RecentymuchProgresshasbeenmadebothinthemathematicalandmechanicaltheoryandthecomPulertechnologysothatevent…     

Forging penetration efficiency of steel H13 stepped shaft radial forging with GFM forging machine

The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM (Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finite element code DEFORM 3D. According to the effective plastic strain, the mean stress and the mean plastic strain distribution of the radial forging, the forging penetration efficiency (FPE) was studied throughout each operation. The results show that the effective plastic strain in the center of the forging is always greater than zero for the desirable larger axial drawing velocity. The mean stress in the center of the workpiece is proposed to describe hydrostatic pressure in this paper. There is compressive strain layer beneath the surface of the workpiece to be found, while there is tensile strain core in the center of the workpiece. These results could be a valuable reference for designing the similar forging operations.     

RECENT DEVELOPMENT OF PROCESS SIMULATION AND ITS APPLICATIONS TO MANUFACTURING PROCESSES

l.IntroductionThemostboortantdrivingforceinmanufacturillistoPrOduCeabetterPrOductatalowercost.GenerallyeffecthemethodsinchideshOrtenintheleadtiminthedesigncyCle,andredUcinthetoolingcostandmaChinedOWnmeatProductionst4e.AllOfthemrewtabettertmderstandingofhO…     

增力式多向镦锻装置的研制

在通用压机上生产类似全纤维曲轴一类锻件的先进工艺为多向镦锻法。本文设计的新型增力式多向钮锻装置，在锻造接近结束时，可以增大水平锹粗力，其增力效果超过传统的ＲＲ锻造法及ＴＲ锻造法。     

Two step forging process of spur gear based on rigid parallel motion

To improve the forging process of spur gear,the metal flow rule is investigated in detail,and a hypothesis of radial rigid-parallel-motive (RPM) flow mode is given. Based on the RPM mode a novel specific gear forging technology is put forward by introduced upend forging process and constrained divided-flow technique. Firstly,finite element method is used to simulate the upend forging pre-forming and RPM finish forging,and equivalent stress field and load-stroke curve are investigated. Secondly,a correspondi...     

Research on voids deformation welding condition for manufacturing of heavy forgings

Crushing and diffusion welding are two critical healing stages of interior void defects in heavy forgings. The healing result depends on many factors during the forging process, such as stress, temperature, deformation and type of material, while the void diffusion welding condition is still not well known at the present. This paper is concerned with the deformation welding condition of the closed void interface in heavy ingot during the hot forging process. A void crushing experiment is carried out to recognize the microstructure of the closed void interface. According to the healing mechanism at high temperature, a new physical simulation model is setup to study the deformation welding process of the closed void interface based on the theory of atom diffusion and the interface contact mechanics prototype. Compared with the experimental results, the influence of deformation degree, forming temperature and holding time on the welding quality is discussed, and then the deformation welding condition of closed void interface is presented. The proposed condition helps to improve forging technology and product quality.     

Forming path optimization for press bending of aluminum alloy aircraft integral panel

Because of the light weight, high stiffness and high structural efficiency, aluminium alloy integral panels are widely used on modern aircrafts. Press bend forming has many advantages, and it becomes a significant technique in aircraft manufacturing field. In order to design the press bend forming path for aircraft integral panels, we propose a novel optimization method which integrates the finite element method (FEM) equivalent model based on our previous study, the artificial neural network response surface, and the genetic algorithm. First, a multi-step press bend forming FEM equivalent model is established, with which the FEM experiments designed with Taguchi method are performed. Then, the back-propagation (BP) neural network response surface is developed with the sample data from the FEM experiments. Further more, genetic algorithm (GA) is applied with the neural network response surface as the objective function. Finally, experimental and simulation verifications are carried out on a single stiffener specimen. The forming error of the panel formed with the optimal path is only 5.37% and the calculating efficiency has been improved by 90.64%. Therefore, this novel optimization method is quite efficient and indispensable for the press bend forming path designing.     

突缘叉模锻件折叠缺陷分析

通过对缺陷的内部结构进行分析,发现突缘叉锻件法兰底面产生缺陷的主要原因是模锻前制坯工艺不合理,造成模锻时金属回流,产生折叠.提出改进制坯工艺消除锻件的缺陷的方案,经工艺和生产验证,消除了锻件缺陷,提高了锻件质量,取得满意效果,该工艺的成功应用,可为同类型产品的生产提供借鉴.     

大直径曲轴自由锻成形工艺探讨

曲轴是各种内燃机中不可缺少的关键部件,它的寿命常常代表该内燃机的使用寿命。单纯从成形的角度考虑,用铸造的方法生产曲轴毛坯是最容易不过的事情。但由于铸造是一个金属冶炼且在砂型中凝固的过程,难以避免会出现夹渣、气空、白点等铸造缺陷而无法满足性能要求。工业上多采用各种压力加工方法来生产曲轴毛坯。小型内燃机上使用的尺寸和重量不大的曲轴一般采用模锻来大批量生产,尺寸较大特别是很大尺寸的曲轴就必需用其它的压力加工方法了。这里仅对特大尺寸的曲轴的自由锻成形工艺进行一些探讨。     

数控回转头冲床自动编程系统

介绍了《数控回转头冲床自动编程系统》的功能和设计特点。它利用中Ｗｉｎｄｏｗｓ９５作为系统工作平台，直接利用产品设计时零件在计算机内的图形信息，采用人机交互方式进行数控编程，此系统适用于数控回转头冲床的自动编程，它是板金计算机辅助设计与制造（ＣＡＤ／ＣＡＭ）开发的关键。     

模具制造中的高速切削技术分析

随着国家高新技术产业的快速发展,对模具制造业也提出较高要求,传统的模具制造通常采用先铣削再淬硬,然后电火花加工及后续抛磨,制造工艺复杂、加工效率低、能源消耗高、污染较大。高速切削技术应用在模具制造业中,可以直接通过高速硬切削获得较高的精度及表面质量,高速切削技术制造工艺过程简单、加工效率较高、能源消耗少、污染较小且具有良好的经济效益,因此,适宜在模具加工中广泛推广应用。     

基于技术进步的观点,对金属材料成型中数值模拟的讨论

基于技术进步的观点,本文分析了在金属材料成型数值模拟软件开发中,可应用的新技术—即面向对象的程序设计方法,友好的输出界面和数值模拟软件与CAD／CAM软件的集成。     

Numerical study of the forming process of high frequency welded pipe

The roll forming process is applied to the manufacturing of high frequency welded (HFW) pipes,section steels,etc. In this paper,the roll forming process of the HFW pipe is simulated with the finite element method (FEM). A user-defined material routine of the commercial finite element code ABAQUS/Explicit is developed,and the mixed hardening constitution model is realized through the user-defined material routine. Based on the mixed hardening constitutive equation,the numerical simulation of roll forming pro...     

The Numerical Simulation on Hollow Part''''s Precise Sizing Process With Cross-wedge Rolling

ThepaperwassponsoredbyPanDengBprojectIntroductionThecrosswedgerollingprocesshasmnyadVatages.ItisaldndofneweffectiveandeconomictechnologythatProducesstePPedshaft.ThetOchnologyhowtoimPovetheaccuracyofworkPiecehasbeingdeVeoped.ThediametertoleraneofsolidpartscanbelimitedbetWeen0.2mmto0.5mm.Thelengthtolerancerangedbforeen0.2nuntolmm.TheaccuracyofpatscouldsatsfythePfOcisionlevelofthetoleranceandmachiningallowancesofsteeldieforeingChinesenationalstandard.[l]Butthediametertoleranceofhollowpeds…     

货车冲压件CAPP系统的研究

针对货车板材冲压件,就开发其CAPP系统进行了研究。以成组技术的基本原理为依据,提出了零件描述和工艺过程生成的新方法,其主要特点是:计算机辅助编码,运用专家知识库进行决策判断,检索与创成相结合。系统采用模块化的设计方法,做到了系统的柔性化。系统采用了汉字DBASE数据库和MS-PASCAL语言,适用于IBM-PC机及其兼容机。     

王冠盖PVC内衬垫材料与设备适应性改进

针对大连制盖厂１９９１年引进设备－－ＩＮＰ胶体热模塑衬垫机的模压头与原引进生产线的自动冲床的冲头不配套，导致注衬垫时内衬垫材料外溢，影响瓶盖的密封性能这一问题，通过改进内衬材料配方和高速模塑压头，成功地解决了这一问题。     

冷弯成型过程的有限元模拟

概述了冷弯成型过程有限元数值模拟的基本原理和基本算法，利用ANSYS／LS—DYNA分析软件对冷弯过程进行有限元数值模拟，并对模拟结果进行受力和应变分析以验证其可行性和正确性，为冷弯成型的工程设计提供了科学依据，从而降低设计风险。     

KEY TECHNOLOGY IN INTELLIGENT CONTROL FOR SHEET METAL DEEP DRAWING

Introduction　　 With development of economics and furtheropening,competitions in market are intensive.The margin between the material cost and price ofproducts becomes small,which compels companiesto pursue higher rate of productivity and quality.The rate of productivity has been improvedthrough high pressing automation,but in order toget satisfactory quality of products under distur-bances,on- line measurement,identification,pre-diction and on- line control must be realized. Intel-ligentcont…