Computer-aided structural design of drawing dies for stamping processes based on functional features

This paper describes a structural design system for 3D drawing dies based on functional features using a minimum set of initial information. In addition, it is also applicable to assign the functional features flexibly before accomplishing the design of a solid model for the main parts of a drawing die, such as upper die, lower die, and blank holder. The initial information includes blank sizes, work strokes, die faces, punch open lines, and press data. The proposed system integrated the design knowledge of drawing die into functions of 3D computer-aided design (CAD) software to automate design and to shorten design time. This design system is constructed on a PC and integrated with a Pro/ENGINEER CAD system including feature selector, shape calculator, model generator, design coordinator, and user interface. The proposed system is demonstrated using the example of designing a drawing die for the roof panel of a vehicle within 1 h. The results reveal that it can dramatically improve the design quality and can save both time and costs with excellent design quality.     

Optimization of the design parameters of modified die in hydro-mechanical deep drawing using LS-DYNA

The use of a modified die enhances the limiting draw ratio compared to that obtainable in a conventional deep drawing operation. Application of these dies, in conventional deep drawing, eliminated the use of blank holder but enhances the tendency of wrinkling in drawn products. In hydro-mechanical deep drawing process, the punch deforms the blank to its final shape by moving against a controlled pressurized fluid. In this paper, a new concept of the application of modified dies in hydro-mechanical deep drawing is presented. The finite element (FE) simulations of a deep-drawing process using modified dies are performed using the 2-D explicit finite element code LS-DYNA, with the aim of optimization of design parameters and the results are compared with the experimental values. The initial design steps in the design of modified die in finite element simulation were taken from the concept of Tractrix die. The use of Tractrix die enhances the draw ratio but simultaneously increases the tendency of wrinkling. In this paper the design parameters of modified Tractrix die for hydro-mechanical deep drawing are optimized for the successful drawing of cups. It is also experimentally verified that by using such modified dies in hydro-mechanical deep drawing, deeper cups are drawn without wrinkling.     

传动轴冷拔模具结构参数优化仿真设计

利用有限元法对传动轴冷拔过程进行模拟仿真,通过正交实验法研究模具结构参数（工作锥半角a、过渡圆弧半径R、定径带长度t）对传动轴冷拔成形的影响,模拟分析得到最小拉拔力、最小径向压应力及最小等效残余应力条件下最优模具参数组合为-＇Or=5。、尺：5mm、L。=4mm。在此基础上对优化方案和传统的设计方案进行了模拟比较分析,结果表明优化的模具结构比传统的方案更好,有利于提高冷拔制品质量,延长模具寿命。     

Application of the fuzzy-based Taguchi method for the structural design of drawing dies

In the sheet metal stamping process for automobiles, the drawing process requires the greatest stamping force, and thus the structure of the drawing dies is the thickest and heaviest among all stamping dies. This study describes how the fuzzy-based Taguchi method can be applied to explore multi-objective optimization in the structural design of drawing dies. Using the lower die of the drawing die for the engine hood??s outer panel as an example, the current study explores four parameters that primarily influence the strength and weight of their structure, namely the rib thickness of the punch open line, the pitch of the structure rib, the thickness of the punch surface, and the thickness of the structure rib. Firstly, CATIA software is used to construct a geometric model of the drawing die, and a structural analysis of the model is performed. Next, within the constraints of allowable stress, allowable deflection and allowable size and pitch of the rib, etc., we apply the Taguchi method to evaluate the allowable characteristics of the two objective functions, namely the deflection and weight of the lower die. Then, through factor effect analysis and analysis of variance, the influences of the design parameters upon the objective functions are determined. Next, a fuzzy logic inference is utilized to obtain the measuring index which results in the optimization of the multiple performance characteristics. Finally, by comparing the results from the maximized design and the results from the original design, it is shown that the deflection of the lower die structure is only increased by 0.0038?mm (8.1%), but its weight can be greatly decreased by 506?kg (12%).     

A Surface Area Calculation and CAPP System for Non-Axisymmetric Deep Drawing Products

In this paper a surface area calculation for non-axisymmetric deep drawing products of elliptical shape was constructed for the design of blank shapes of deep drawing products by using an AutoLISP function in AutoCAD software. A computer-aided process planning (CAPP) system for rotationally symmetric deep drawing products has been developed. In this study, a CAPP system for non-axisymmetric deep drawing products of elliptical shape was constructed using process sequence design. The system developed consists of four modules. The first is the recognition of shape module for recognising non-axisymmetric products. The second is a 3D modelling module for calculating the surface area for non-axisymmetric products. The third is a blank design module for creating an oval-shaped blank with an identical surface area. The fourth is a process planning module based on production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by interviewing field engineers. The drawing coefficient, the punch and die radii for elliptical shape products are considered as the main design parameters. The suitability of this system was verified by applying it to a real deep drawing product. This surface area calculation and CAPP system should be very useful for reducing the lead-time for manufacturing and for improving the accuracy of products.     

On the optimal die curvature in deep drawing processes

The paper presents an attempt to increase the limit drawing ratio of deep drawing processes by searching an optimal die curvature, which minimizes the drawing load. The search done here for an optimal die curvature is based on experimental observations and followed by a detailed upper bound analysis. The analysis takes into account the non-steady character of the process (from a 2D circular plane blank into a 3D axisymmetric cup). The plastic flow along the die curvature is expressed in a toroidal coordinate system which seemingly describes more naturally a smooth velocity field along the real toroidal profile of the die. The outcome provides more closely the relationship between the energy dissipation rate and the die curvature so that a preferred die curvature is obtainable by energy minimization.Circular sheet blanks, made from aluminum and copper, were drawn through dies with different radii of curvature (with at least five repetitions at each radius) to capture the features of the optimal dies whenever exists.The main result is that under certain circumstances an optimal die curvature does exist. It depends largely on the drawing ratio and the blank/die interfacial friction, m, but appears quite insensitive to the initial thickness of the blanks. The optimal die curvature is pronounced in the cases where the frictional resistance is relatively low, otherwise it is indistinctable and remains practically undeterminable by designers.     

A Study of the Progressive Working of an Electric Product Using a 3D Shape Recognition Method

This paper describes the development of the computer-aided design of an electric product using bending and piercing operations for progressive working. The system is based on knowledge-based rules. Knowledge for the system is formulated from plasticity theories, experimental results, and the empirical knowledge of field experts. The system has been written in AutoLISP in AutoCAD on a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, strip layout, and die layout modules. Based on knowledge-based rules, the system is designed considering several factors, such as bending radius, bending angle, effect of springback, material and thickness of a product, bending sequence, and the complexities of the blank geometry and punch profiles. It generates the 3D strip layout drawing for an electric product. The die layout module carries out die design for each process from the results of the strip layout module. Results obtained using the modules enable the designer and manufacturer of piercing and bending dies to be more efficient in this field.     

An Integrated Design and CAPP System for Deep Drawing or Blanking Products

This paper deals with an automated computer-aided process planning system by which designers can determine operation sequences even if they have little experience in the process planning of sheet metal products by press working. The computer- aided process planning program written in AutoLISP for the AutoCAD using a personal computer, for deep drawing or blanking, requires many kinds of technical and empirical skills. The approach to structure of the system is based on knowledge-based rules, and a process knowledge base consisting of design rules is built. Based on the investigation and collection of knowledge about the processes, the methodology adopted to develop this system is described in this paper. An attempt is made to link programs incorporating a number of expert design rules to form a useful package for process planing. This integrated design and CAPP system is composed of two main modules and six submodules. It is designed considering several factors, such as the complexities of blank geometry, punch and die profiles, the availability of a press equipment, and standard parts. Results obtained using the modules enable the designer and manufacturer of deep drawing or blanking dies to be more efficient in this field.     

圆锥形凹模径向分块压边拉深工艺实验研究

采用圆锥形凹模拉深工艺可以提高成形极限,但需要用压边圈将板坯先压成与凹模面吻合的形状,当变形程度较大时,板坯很容易起皱。为了克服这一缺点,提出了将圆锥形凹模与径向分块压边方法结合的工艺,该工艺可有效改善压边圈与板坯的约束状态,从而达到抑制起皱的目的。对圆筒形件的拉深成形,采用了刚柔复合的径向分块压边圈结构,设计了圆锥形凹模径向分块多压边圈拉深模,取不同凹模半锥角的圆锥形凹模进行了圆筒形件的拉深成形实验。实验表明,新的压边方法能有效克服初始成形过程的起皱,可与锥度较小的凹模一起使用。采用凹模半锥角为45°的凹模,得到AA5754、AA6061和08Al三种板材的极限拉深系数分别为0.410、0.431、0.373,显著提高了成形极限。对圆锥形凹模的拉深成形,给出了理论计算成形极限的方法,理论与实验结果非常接近。     

正交试验设计在TA2筒形件拉深成形过程中的应用

研究了TA2筒形件的拉深成形过程,对无压边圈情况下拉深成形的5个因素(凹模入口圆角、凸凹模间隙、模具与板坯之间润滑系数、凸模圆角、坯料直径)进行了有限元数值模拟及其正交试验,提出了采用成形后板坯最大厚度与最小厚度之差Δt的概念来作为描述零件成形结果的评价标准,且论证了采用该评价标准的合理性。对试验结果进行了直观分析和方差分析,得出了各因素对拉深成形过程的影响次序及显著性。     

The effect of die/blank holder and punch radiuses on limit drawing ratio in angular deep-drawing dies

Deep-drawing is one of the most important methods used to form sheet metal. The radius of die/blank holder and punch is important for deep-drawing dies because of an effective way to promote deep drawability sheet metal. This paper presents an attempt to determine the effect of various radiuses of die and punch on the limit drawing ratio and was investigated using DIN EN 10130–91 sheet metal. The die/blank holder profile with angles of α?=?0°, α?=?2.5°, α?=?7.5°, α?=?12.5°, α?=?15° and die/punch profile with radiuses for R?=?10, R?=?8, R?=?6, R?=?4 and R?=?0 mm were analyzed to determine the influence of punch force on the limit drawing ratio. The aim of this study is to investigate the effect of radius and angle variables on drawability in the deep-drawing process and to obtain useful data from the industrial field. The experiments show that the limit drawing ratio increased with increasing radius of punch (R), die/blank holder angle (α).     

Development of an automated progressive design system with multiple processes (piercing, bending, and deep drawing) for manufacturing products

This paper describes the research work involved in developing an automated progressive design system with multiple processes such as piercing, bending, and deep drawing for manufacturing products. This approach to make a progressive, flexible working system is based on knowledge-based rules. The knowledge required for this system is formulated from plasticity theories, experimental results, and the empirical knowledge of field experts. The system consists of three main modules: shape treatment, strip layout, and die layout modules. The system is founded on knowledge-based rules and is designed in consideration of several factors, such as the material and thickness of a product, the piercing, bending and deep drawing sequence, and the complexities of blank geometry and punch profiles. The system then generates the strip layout drawing for an automobile product. The die layout module carries out the die design for each process from the results of the strip layout module. The results obtained using the modules enable the designers of manufacturing products with multiple processes to be more efficient in this field.     

Integration of artificial neural network and simulated annealing algorithm to optimize deep drawing process

Deep drawing is characterized by very complicated deformation affected by the process parameter values including die geometry, blank holder force, material properties, and frictional conditions. The aim of this study is to model and optimize the deep drawing process for stainless steel 304 (SUS304). To achieve the purpose, die radius, punch radius, blank holder force, and frictional conditions are designated as input parameters. Thinning, as one of the major failure modes in deep drawn parts, is considered as the process output parameter. Based on the results of finite element (FE) analysis, an artificial neural network (ANN) has been developed, as a predictor, to relate important process parameters to process output characteristics. The proposed feed forward back propagation ANN is trained and tested with pairs of input/output data obtained from FE analysis. To verify the FE model, the results obtained from the FE model were compared with those of several experimental tests. Afterward, the ANN is integrated into a simulated annealing algorithm to optimize the process parameters. Optimization results indicate that by selecting the proper process parameter settings, uniform wall thickness with minimum thinning can be achieved.     

T型螺栓的热镦锻

介绍了用一副模具通过调换其中的成型模可热镦锻各种规格T型槽螺栓的方法，以及头部成形料的计算和应用实例。     

New strip drawing experiments using transparent sapphire dies

Experimental results are presented for carefully controlled plane-strain strip drawing experiments. Transparent aluminum oxide (sapphire) dies have been used to make direct observations of the die-work interface in strip drawing, including the distortion of scribed lines which were used for estimating velocity profiles at the interface. Such profiles can be used as input to theoretical models (Appleby et al., 1984), thus permitting the calculation of interface friction rather than requiring its assumption. Experiments were conducted with tungsten carbide, as well as sapphire, dies in which process parameters such as reduction, speed, die angle, lubricant, and back tension were varied, and die separating forces and drawing loads were measured. In general the friction was lower for the sapphire dies, but the variation with process parameters was similar. For one experiment, residual stresses in the product strip were measured. The results are believed to be documented in sufficient detail to be of general use in evaluating theoretical models.     

基于并行工程的汽车覆盖件模具开发应用研究

本文分析了汽车覆盖件模具开发过程中各活动和过程的功能及作用,讨论了应用并行工程的开发理念对覆盖件模具进行开发的可行性,并阐述了基于并行工程进行覆盖件冲压模具开发所需的各种关键技术,最后建立了覆盖件拉深模结构并行设计的过程模型。     

基于有限元模拟的铜包铝线拉拔参数优化

为研究拉拔参数对铜包铝线质量的影响,运用有限元方法对金刚石涂层拉拔模具拉拔铜包铝线的过程进行了模拟仿真,研究了拉拔过程中模具的应力分布情况,分析了压缩率对铜包铝线残余应力分布均匀性的影响规律。利用正交实验法研究了拉拔参数(工作锥半角α,定径带长度L,过渡圆弧半径R,压缩率β)对铜包铝线尺寸精度和残余应力分布均匀性的影响,获得了最佳拉拔参数(α=6°,L=4.5 mm,R=3 mm,β=1.82%)和各因素对分析指标的影响规律。并在此基础上对优化方案进行了模拟,结果证明了正交实验对拉拔参数优化的有效性,对金刚石涂层拉拔模具的设计及高质量铜包铝线的拉制有重要的指导意义。     

A hybrid NN-FE approach to adjust blank holder gap over punch stroke in deep drawing process

In deep drawing process, the blank holder plays a key role in adjustment of metal flow into the die cavity. Moreover, the quality of drawn parts is extremely affected by this flow. There are two methods of treating the blank holder in deep drawing and its simulation. One is blank holder force (BHF) and the other is blank holder gap (BHG), defined as the fixed distance between the blank holder and the die surface. In previous studies, a large number of experimental techniques have been used to study BHF; however, the amount of theoretical and numerical simulation work to study BHG is insufficient. In the present study, the concept of BHG profile, i.e., variation of BHG over punch stroke is introduced and it is shown that a properly selected BHG profile can improve the section thickness of formed part and result in the drawing of deeper parts. Here, two methods for the optimization of BHG profile are devised, i.e., the local optimization and the global optimization methods. In the first approach, the best BHG in each punch step is determined and finally, the local optimized BHG profile is achieved. In the second method, however, the empirical model for the prediction of final minimum section thickness in terms of BHG profile is obtained using design of experiments and neural networks. In the next stage, the proposed model is implanted into a simulated annealing optimization procedure to identify a proper BHG profile that can produce the desired blank thickness. Afterward, the BHG profile approach is applied to a variety of initial thicknesses, blank diameters, and materials in order to examine the robustness of method. In this paper, ABAQUS finite element package is used to gather finite element (FE) data and several experiments are performed to verify the FE results.