板料形状、压料筋的设置对汽车覆盖件成形中起皱和未充分拉深的影响

在汽车覆盖件成形工艺中,无论是对外观还是对功能的要求,起皱和未充分拉深问题是不允许出现的,因此对起皱和未充分拉深问题的预测和防止显得非常重要的。采用数值模拟技术可以在模具设计初期预测产品的几何形状,从而优化工艺参数以便获得高质量的成品。文章以eta/DYNAFORM有限元分析软件为平台,采用弹-塑性有限元法对DDQS钢进行数值模拟,得出相应的FLD曲线、起皱和未充分拉深区域。重点探讨了板料形状和压料筋的设置对起皱和未充分拉深区域的影响,得出了较好的解决方案。     

变压边力拉深的原理及实验系统

板料拉深过程中,压边力是一种重要的工艺参数。由于其在冲压拉深过程中的重要作用及在生产中易于调节、控制,近年来一些汽车工业较为发达的国家,正在进行着变压边力拉深新工艺方法的研究。本文从板料冲压拉深过程对压边力需求的分析中,提出了变压边力控制方法的原理,建立了变压边力拉深实验系统,并以圆锥形件为研究对象对拉深过程中合理的变压边力控制问题进行了探索性研究,取得了阶段性成果。     

A compact and practical CAD system for blanking or piercing of irregular-shaped sheet metal products and stator and rotor parts

This paper describes the development of a computer-aided design of blanking and piercing for irregular-shaped sheet metal products and stator and rotor parts. An approach to the compact and practical CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of six main modules, which are input and shape treatment, production feasibility check, blank layout, strip layout, die layout, and drawing edit module. Based on knowledge-based rules, the system, STRTDES, is designed by considering several factors, such as complexities of blank geometry and punch profile, availability of press equipment and standard parts, utilization ratio which minimizes the scrap in a single or a pairwise operation, bridge width, grain orientation and design requirements which maximize the strength of the part when subsequent bending is involved. Therefore, this system can carry out a die design for each process which is obtained from the results of an automated blank layout drawing with the best utilization ratio for the irregular shape of the product, which was successful in the production feasibility check module, and those of an automated strip layout drawing. It can then generate part drawings and the assembly drawing of the die set in graphic form. The developed system provides its efficiency and effectiveness for blank layout, strip layout, and die layout of irregular-shaped sheet metal products and stator and rotor parts.     

汽车覆盖件拉深过程中的压边力预测

结合数值模拟与人工神经网络技术研究了汽车内覆盖件承载地板在冲压成形中压边力的预测。将板料模型零件导入到Dynaform中进行网格划分并对其拉深过程进行模拟仿真,结合正交试验获取不同参数条件下最佳压边力的数据样本,然后运用Matlab软件中的GRNN神经网络工具箱对数据进行训练学习,采用训练好的神经网络对板料成形过程中的压边力进行预测,获得了板料拉深过程中的压边力变化曲线。通过预测结果和模拟结果对比,预测误差在10%以内。将预测的曲线对零件模拟仿真,结果显示零件最大减薄率在25%以内,并对板料进行实际冲压验证。结果显示成形效果良好,无起皱、破裂缺陷,符合实际生产的要求,说明GRNN神经网络可以用于零件冲压过程中压边力的预测。     

铝合金板材电磁脉冲拉深实验与有限元模拟

在金属板材的电磁脉冲拉深成形中,采用一种使成形件凸缘部分的材料可以径向流动的方法。形成了一种拉深—胀形特点相结合的成形工艺,可以提高材料的拉深极限。在此基础上通过改变电压和板料直径等工艺参数,可获得更大拉深高度。     

Numerical analysis of the potential of deep drawing processes with hydrostatic pressure lubrication

Deep drawing is one of the most important forming procedures for the economic production of sheet metal components. Especially for high-volume parts, deep drawing is a very efficient method of fabrication with high utilization of semi-finished parts. Certainly, conventional deep drawing processes are restricted by forming limits due to part failure during the drawing process. The process force is one of the most important factors for this restriction. The narrow process window, especially for deep drawing of light-weight materials, can be extended by reducing the friction forces at the die radius, using hydrostatic pressure lubrication. After the numerical analysis of the appearing loads of deep drawing processes, the optimal position for the insertion of pressurized lubricant was identified and the potential of the hydrostatic pressure lubrication was predicted. With experimental tests, the results of the simulations were approved. Both, the simulations and the experimental tests showed a significant reduction of the process forces.     

On the acting pressure in laser deep drawing

Through the continuing trend of miniaturization new cost efficient and fast methods for processing of small parts are required. In this paper a non-mechanical process for the forming process of micro deep drawing is presented. This new pulsed laser based deep drawing process utilizes an initiated plasma shock wave at the target, which forms the sheet. Several pulses can be applied at one point and therefore high forming degrees can be reached without increasing the energy density. In this article the pressure of the shock wave is measured and optimized. Furthermore laser deep drawing of samples made out of pure aluminum, copper and stainless steel sheet metal with thicknesses of 20 and 50 μm are shown. Finally the forming behavior after single pulses is presented.     

多弯角车身钣金件多工位级进模设计与应用

为避免冲压过程中多弯角结构引起的零件内部孔形和外部轮廓的边界误差导致级进模技术实施失败,以多弯角车身钣金件为对象,分析了制件的多弯角冲压成形工艺方案,设计了毛坯排样图;其次,应用单工位全工序有限元法(FEM,Finite Element Method),分析了零件的冲压成形过程,验证了冲压工艺参数与工艺方案的可行性;再次,以所设计的毛坯排样图为基础,对多弯角车身钣金件级进模进行结构概要与工序结构设计,设计并制造了1套13工位级进模;最后,进行了实冲试验,试验获得的制件外观质量好、表面光滑、无起皱与破裂等成形性问题,且关键成形部位精度达到了零件图的设计要求。试验表明:所设计的级进模能够满足企业的生产要求,且设计过程是合理的。     

A servo motor driven multi-action press for sheet metal forming

The goal of the current study is to adapt a servo-motor driven multi-action press for forming of sheet metal parts under precise velocity control and variable blankholding force. The Engineering Research Center for Net Shape Manufacturing [ERC/NSM] has developed a computer controlled multi-action press with two independently driven punches for research in cold forming of complex parts, using physical modeling techniques. Recently, the same press was modified and upgraded for use in sheet metal forming. As a result of its special design and construction, this press is highly controllable and can perform a wide range of sheet metal forming processes. Tests were conducted in order to obtain the actual press characteristics. Axisymmetric deep drawing experiments were performed with 1100-O annealed aluminum material using all three actions of the press. In these preliminary experiments, the crucial role of blankholding force control on final product quality and drawability was established.     

Hybrid additive manufacturing of metal laminated forming tools

Deep drawing dies are manufactured using metal sheets. Laser metal deposition is used for bonding the sheets and smoothening the edges. The strength and surface finish of the dies are the key challenges. Milling, roller burnishing, and laser treatment are applied as post-processing for improving the surface finish. A semi-analytical model is developed for selecting the sheet combination for sufficient strength. The new rapid prototyping process offers high flexibility for complex die geometries. The evaluation by deep drawing experiments using DC06 and high-strength HC380LA blanks revealed the feasibility of the new manufacturing routes regarding deep drawability and surface finish.     

板料增量成形的研究进展

板料增量成形是采用简单模具对板料进行逐次塑性加工的一种工艺,不需要专用的模具就可以成形较为复杂的零件,同时还具有成形力小、柔性高的特点,特别适合多品种小批量零件的生产方式,因此得到国内外学者的重视。本文重点从板料的增量压弯成形、增量拉深胀形、增量微成形3个方面对板料增量成形的发展进行综述,还对板料增量成形工艺的发展前景进行了展望,指出进行理论创新、开发新的模拟软件、探索新的成形方案、开发增量成形新设备是发展趋势。     

基于神经网络的材料性能参数和摩擦系数的实时识别

在板材拉深成形智能化控制过程中 ,为了避免缺陷的产生 ,必须适时地改变控制工艺参数 ,而最佳控制参数要根据材料的性能参数和摩擦系数来预测。根据拉深成形过程的特点及生产过程中自动化程度的要求 ,建立了材料性能参数和摩擦系数识别的人工神经网络模型。利用神经网络这种新一代信息处理工具实现了材料性能参数和摩擦系数的实时识别 ,为实现板材拉深成形过程的智能化控制奠定了基础     

汽车后围板拉深成形过程中的回弹预测

以汽车后围板为对象,运用BP神经网络对其拉深过程中的回弹量进行预测。通过CATIA建立CAD模型,运用Dynaform软件对板料冲压过程进行仿真分析,借助正交试验获取不同参数组合下的回弹数据,并通过试验验证了关键数据的可靠性,建立了4-9-6的3层BP神经网络回弹预测模型。通过对数据样本进行训练学习,控制其预测的精度为0.01,将预测结果与实际测量结果进行对比,显示预测误差最大为5.62%。说明运用BP神经网络可以实现对复杂拉深件成形的回弹预测,可以大量节省仿真预测的时间,对模具的设计具有很好的指导作用。     

薄壁不锈钢筒形件级进模设计

分析了薄壁不锈钢筒形件连续拉深工艺,采用圆锥形凹模和平凹模相结合的级进模结构,既可避免不锈钢筒薄壁拉深起皱和断裂现象,又保证零件尺寸精度。在有余热的软化退火板料上涂覆氯化石蜡润滑,使润滑剂均匀粘附在板料表面,润滑效果好。减少了中间退火工序,生产效率大大提高。     

基于AutoForm的阶梯盒形件冲压工艺模拟及优化

阶梯盒形件是汽车制造业中的典型零件,但是由于其拉伸成形困难,废品率较高.针对某阶梯盒形件进行了工艺性分析,规划了冲压生产工艺,并利用AutoForm软件对拉伸成形过程进行了仿真模拟,选取板料尺寸、摩擦系数及压边力为研究对象,对比分析了3个参数对拉伸质量的影响规律,最后给出了优化成形质量的建议,对指导实际生产有一定的意义...     

变压边力对矩形件成形性能的影响

起皱和断裂是板料成形过程的主要失效模式 ,合理控制成形过程中压边力 ,可以消除这些缺陷 ,提高成形性能。本文通过对随位置变化的变压边力作用下的矩形盒拉深过程进行数值模拟 ,研究各部位压边力变化对整体成形性能影响、及其影响范围 ,为分块压边圈的压边力的调整提供一定的依据。     

Investigations of ductile damage during the process chains of toothed functional components manufactured by sheet-bulk metal forming

Sheet-bulk metal forming processes combine conventional sheet forming processes with bulk forming of sheet semi-finished parts. In these processes the sheets undergo complex forming histories. Due to in- and out-of-plane material flow and large accumulated plastic strains, the conventional failure prediction methods for sheet metal forming such as forming limit curve fall short. As a remedy, damage models can be applied to model damage evolution during those processes. In this study, damage evolution during the production of two different toothed components from DC04 steel is investigated. In both setups, a deep drawn cup is upset to form a circumferential gearing. However, the two final products have different dimensions and forming histories. Due to combined deep drawing and upsetting processes, the material flow on the cup walls is three-dimensional and non-proportional. In this study, the numerical and experimental investigations for those parts are presented and compared. Damage evolution in the process chains is simulated with a Lemaitre damage criterion. Microstructural analysis by scanning electron microscopy is performed in the regions with high mechanical loading. It is observed that the evolution of voids in terms of void volume fraction is strongly dependent on the deformation path. The comparison of simulation results with microstructural data shows that the void volume fraction decreases in the upsetting stage after an initial increase in the drawing stage. Moreover, the concurrent numerical and microstructural analysis provides evidence that the void volume fraction decreases during compression in sheet-bulk metal forming.     

Experimental and numerical study on shaping of aluminum sheets with integrated piezoceramic fibers

Force-fit integration of piezoceramic fibers in micro-formed structures is a new approach for function integration in structural sheet metal parts. In a first step, a micro-structured surface is formed in a planar semi-finished sheet metal part by micro-impact extrusion. Piezoceramic fibers are then assembled into this micro-structured surface with a small assembly clearance. The fibers and the structured surface of the sheet metal are joined by a forming process. In the next step, the sheet metal with piezoceramic fibres within a locally micro-formed substructure is shaped by deep drawing into a 3D-geometry. In this paper, results of the micro-impact extrusion and the joining by forming experiments are presented. Furthermore, the design constraints for assembly and joining due to the dimensional and form deviations of the piezoceramic fibers are discussed. Results of a numerical study of micro-forming, joining by forming and the global loading during a deep drawing process step were in good agreement with the experimental investigations. The direct comparison between experiment and numerical simulation increases the process knowledge and shows further improvement potential.     

Adaptive FEM simulation for prediction of variable blank holder force in conical cup drawing

Fracture and wrinkling are two primary failure modes in deep drawing of sheet metal parts. Previous studies showed that properly selected variable blank holder force (BHF) profile, i.e. variation of BHF with punch stroke, can eliminate these failures to draw deeper parts. In this study, an adaptive simulation strategy was developed to adjust the magnitude of the BHF continuously during the simulation process. Thus, a BHF profile is predicted in a single process simulation run and the computation time is reduced. The proposed strategy has been applied successfully to two conical cup drawing operations. The predictions have been compared with experiments and the results indicate that the adaptive simulation strategy can also be used to improve the drawing process for forming non-symmetric parts.     

Numerical simulation of two-stage deep drawing of complex-shaped parts

1　INTRODUCTIONInrecentyears ,withtherapiddevelopmentofcomputersoftwareandhardware ,andtheintersectionandcombinationofcomputertechnology ,graphics ,mechanicsandprocessengineering ,thecomputeraid edengineering(CAE)technologybasedonnumericalsimulationhasbeenwidelyappliedinthesheetmetalformingfield[1,2 ] .Nevertheless ,untilnow ,thenu mericalsimulationisconfinedtosimulatesomebasicmodesofdeformationsuchasbending ,deepdraw ing ,bulgingandflanging .Forthedeformationofcomplexwork pieces ,forexa…