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.     

Effects of punch load for elliptical deep drawing product of automotive parts

Deep drawing process, one of sheet metal forming methods, is very useful in industrial field because of its efficiency. The production of optimal products using this process is dependent on the process variables such as blank shapes, profile radii of punch and die, and formability of materials. Of the variables, the blank shape is very important since it controls the formability factor. This paper reports the investigations on three kinds of blank shapes and the scribed circle test on three deformation modes. The punch load distribution for elliptical forming processes were measured under different conditions of profile radii of punch and die and discussed here. These experiments clarified the influence of the profile radii of the punch and die and the blank shape on the punch-load distribution for the elliptical deep drawing product of automobile parts. The aim of this study is to investigate the effect that the process variables have on drawability in a non-axisymmetric elliptical deep-drawing process and to obtain useful data from the industrial 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.     

Indexing and retrieval in case-based process planning for multi-stage non-axisymmetric deep drawing

This paper presents a case-based reasoning (CBR) methodology for computer-aided process planning (CAPP) for multi-stage, non-axisymmetric sheet metal deep drawing. The methodology addresses the indexing and retrieval of process planning cases. Planning cases are indexed via a feature-based representation of deep drawn parts. Efficient case retrieval is achieved by a feature-based similarity analysis between a new deep drawn part and existing parts in the case library. An illustrative example is included to demonstrate the operation of the proposed approach and show its effectiveness in speeding up CAPP for multi-stage non-axisymmetric deep drawing. This revised version was published online in April 2005 with a correction to the corresponding author’s address.     

CAPP中轴类零件工序图自动生成技术研究

工序图是工艺设计结果的图形表达形式,其绘制的自动化程度低,是CAPP技术进步的主要瓶颈之一。针对运用AutoLISP二次开发工具以及数据库技术实现工序图自动绘制过程中,计算机对各个图元的自动识别、编辑和操作的要求,提出了一种轴类零件工序图自动生成的新方法,在参数化绘制预处理零件图的过程中,通过给各个图元重新命名完成了零件几何特征信息的存储,并将零件加工工艺信息代码化,采用逆序修改特征的方法实现了轴类零件工序图生成的自动化。研究结果表明,由计算机生成的一套工序图可以准确地反映出零件在从毛坯到成品的制造过程中,零件的形状和尺寸变化情况以及加工工序中的各个工艺要素,对其他类型零件的工序图自动生成也具有一定的参考价值。     

基于VC＋＋的轧辊制造工艺CAPP系统开发

以制造轧辊的生产工艺为研究对象,利用计算机辅助工艺规程设计技术,实现自动编制制造轧辊的生产工艺.选用VC＋＋6.0软件开发工具,对轧辊的生产工艺过程进行编制,使其自动生成毛坯图、机械工艺卡片、工艺设计说明书,实现对制造轧辊的计算机辅助工艺过程设计,形成轧辊制造CAPP系统.     

Java-based computer-aided process planning

This investigation addresses distributed environments for computer-aided process planning (CAPP) over a network. The Java 2 Enterprise Edition (J2EE) standard using Java is applied to implement cross-platform and distributed computing architecture, thus reducing the system loading during manufacturing process planning. The product-oriented standard, standard exchange of product (STEP), model data is applied to define a robust data model that associates product, shape, and feature definitions and provides the mechanisms for data exchange, sharing, and integration with other engineering systems, such as computer-aided design (CAD) and computer-aided manufacturing (CAM). STEP AP224 is engaged to define the machining features of machined products in the proposed CAPP system. The life cycle of a product from design to sale, and especially the period of manufacturing, can be greatly shortened; the cost of manufacturing can be reduced and the quality of the product can be improved using the proposed CAPP system.     

On-line integration of a process planning module with production scheduling

An approach to the on-line integration of process planning and production scheduling is reported. Based on a geometric modeller, a geometric analyser and a knowledge base, the process planner generates alternative process plans and provides automatic tool selection and calculation of the appropriate machining parameters. Time and cost estimations are input to the decision-making module in the production scheduling system that produces optimal scheduling decisions as well as a complete record of the actual state of the factory resources. An information flow, designed as a relational data model, maintains the interaction between the process planning and the production scheduling systems and provides the dynamic feedback to the process planner. Specific geometry features of the blank, the finished part and the cutting tools, and geometry features-based rules are stored in the database of a developed CAPP system by using a separate CAD interface. The integrated production planning and production scheduling system and the CAPP system were validated with rotational parts machining.     

Algorithms for computer-aided generative process planning

Process planning is the function within a manufacturing facility that establishes the machining processes and parameters to be used so as to convert a piece-part from its initial form to the final form predetermined on an engineering drawing. Computer-aided process planning (CAPP) has become a major focus of manufacturing automation as it forms the interface between computer-aided design (CAD) and computer-aided manufacturing (CAM). Issues in CAPP include part representation, process selection, alternative process-plan generation, intermediate surface and tolerance determination, and operation sequencing. This paper focuses on quantitative models for determining cutting dimensions and tolerances for intermediate surfaces, and on a heuristic for sequencing cutting operations.     

An Automated CAD System for Progressive Working of Irregular Shaped Metal Products and Lead Frame for Semiconductors

This paper describes the development of computer-aided design of irregular-shaped sheet metal products and 32LD PLCC lead frames and semiconductors, requiring very precise piercing operations for progressive working. The approach to the CAD system is based on knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results, and the empirical knowledge of field experts. This system has been written in AutoLISP using AutoCAD on a personal computer and the I-DEAS drafting programming language on the I-DEAS master series drafting with an HP 9000/715(64) workstation. Transference of data between Auto-CAD and I-DEAS master series drafting is accomplished using DXF and IGES methods. This system is composed of five main modules, which are input and shape treatment, production feasibility check, strip-layout, data-conversion, and die-layout modules. Based on knowledge-based rules, the system is designed by considering several factors, such as V-notches, dimple, pad chamfer, spank, cavity punch, camber, coined area, cross bow, material and thickness of product, complexities of blank geometry and punch profile, and availability of presses. As forming processes and the die design system using 2D geometry recognition are integrated with the technology of process planning, die design, and CAE analysis, the standardisation of die parts for lead frames requiring a high precision piercing process is possible. The die-layout drawing generated by the die-layout module is displayed in graphic form. Results obtained for each module provide help to the designer and the manufacturer of lead frames for semiconductors.     

SMT-TAB: A process planning system for PCB assembly using TAB and SMT

Process planning is a critical function in any manufacturing domain. This is especially true in the electronics manufacturing area where substantial heuristic and experiential knowledge is commonly used during process plan development. While research in computer-aided process planning (CAPP) has tended to concentrate in the machining realm, few CAPP systems have been developed for electronics manufacturing applications and more specifically for the printed circuit board (PCB) assembly domain. Besides, the CAPP systems that have been developed for this area have dealt with either insertion mount or surface mount PCB assembly processes only.Tape automated bonding (TAB), though a relatively new technology, is gaining importance in electronics assembly owing to its inherent advantages. The advent of fine pitch technology together with the ever increasing need for more inputs/outputs and greater pin counts in integrated circuit applications has enhanced the use of TAB technology in electronics manufacturing. This trend has been further augmented by the increasing need for compactness in consumer electronics.This research designed and developed a prototype CAPP system for the PCB assembly domain. The system developed generates a process plan for PCBs populated with surface mount and/or TAB components. An artificial-intelligence based expert system approach has been used in the design and development of the CAPP system. Outputs generated by the system are presented along with ideas for future research.     

The design of blank’s initial shape in the near net-shape deep drawing of square cup

Deep drawing process is very useful in industrial field because of its efficiency. The deep drawing is affected by many process variables, such as blank shapes, profile radii of punch and die, formability of materials and so on. Especially, in order to obtain the optimal products in deep drawing process, blank shape is very important formability factor. In this paper, the finite element method is used to investigate the cup height of the square cup drawing process. In order to verify the prediction of FEM simulation of the product’s height and forming load in the square cup drawing process, the experimental data are compared with the results of the current simulation. A finite element analysis is also utilized to acquire the designed profile of the drawn products, a reverse forming method for obtaining the initial blank’s shape according to the forward square cup drawing simulation is proposed. The design of initial blank’s shape is also certified to obtain the designed profile of drawn cups by experiment. The influences of the blank’s shape on the height of product, the forming load, the maximum effective stress and the maximum effective strain are also examined.     

Product and manufacturing capability modelling in an integrated CAD/process planning environment

Computer-aided process planning (CAPP) is one of the key components in computer integrated manufacturing (CIM) environment. Fully automatic CAPP systems require information transfer between CAD/CAM systems to be mutual, dynamic, concurrent, automatic and efficient. The difficulty in achieving this is the management of the vast amount of heterogeneous data, knowledge and complicated inference processes encountered in developing automatic planning systems. The objective of the reported research is to develop a framework for modelling and managing engineering product and manufacturing capability information in an integrated feature-based CAD/knowledge-based process planning environment. The feature-based design system is developed with a commercial boundary representation (Brep) solid modeller with additional feature-modelling functions. The process planning system is developed using a knowledge-based system, which is fully integrated with the design system through an information mapping mechanism. Process planning decisions are made by searching for a match between the product requirements and the process capability of available manufacturing systems. This is achieved by invoking the rules coded in an inferencing mechanism (an inference engine). Both the underlying methodologies and the implementation aspects will be addressed in this paper.     

基于PDM的工艺管理研究

工艺是连接产品设计与制造的桥梁，是实现产品信息集成与管理的关键。在研究工艺设计及工艺信息管理的基础上，分析了工艺管理的功能需求，建立了面向产品全生命周期集成的工艺信息模型，提出了基于PDM的两级工艺管理方案，有效地简化了CAPP系统的设计，有利于真正实现CAD、CAPP、CAM、PDM、ERP的全面集成。     

特种轴承参数化CAD/CAPP集成系统研究

通过分析MGA,MGB,MGC和MGD四大系列非标特种轴承的产品及工艺设计过程,建立了涵盖各类轴承产品和工艺设计的参数化模型,研究了计算机集成制造系统环境下用.Net开发基于Web的特种轴承参数化计算机辅助设计/计算机辅助工艺设计系统的实现策略,详细讨论了参数化绘图、设计计算、公差/工艺设计及计算机辅助设计与计算机辅助工艺设计的集成等模块的关键技术.最后,以MGA1型轴承的设计为例,验证了系统的有效性.     

基于加工特征的铸造毛坯生成与合理化

针对现有的CAPP研究很少涉及到铸造毛坯的设计问题,且一般毛坯模型的生成过程比较简单,甚至常常忽略铸造工艺对铸造毛坯制造的要求.以某齿轮箱生产企业的齿轮箱下体箱零件为例,基于该零件的加工特征,在毛坯初始尺寸计算的基础上,将铸造工艺知识引入到CAPP的工艺决策过程,生成初始毛坯的合理化尺寸,并进行合理化修改.同时,对生成的零件加工特征文件进行直接操作,方便快捷地生成合理化的毛坯特征文件,有力地支持了铸造毛坯的设计,实现了CAPP向铸造毛坯领域的有效拓展.     

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.     

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。     

Blank optimization for sheet metal forming using multi-step finite element simulations

The present study aims to determine the optimum blank shape design for deep drawing of arbitrary shaped cups with a uniform trim allowance at the flange, i.e., cups without ears. The earing, or non-uniform flange, is caused by non-uniform material flow and planar anisotropy in the sheet. In this research, a new method for optimum blank shape design using finite element analysis is proposed. The deformation process is first divided into multiple steps. A shape error metric is defined to measure the amount of earing and to compare the deformed shape and target shape set for each stage of the analysis. This error metric is then used to decide whether the blank needs to be modified. The blank geometry change is based on material flow. The cycle is repeated until the converged results are achieved. This iterative design process leads to optimal blank shape. To test the proposed method, three examples of cup drawing are presented. In every case converged results are achieved after a few iterations. The proposed systematic method for optimal blank design is found to be very effective in the deep drawing process and can be further applied to other sheet metal forming applications such as stamping processes.