Experiments dealing with the upsetting of sintered materials have resulted in the determination of a forming limit in terms of the local copressive and tenslis. As the specimen is comperessed, a plot of tensile strain versus compressive strain can be made. Fracture occurs when the strain parth intersects the forming limit. Once the fracture locus is defined by an experimental method, it is possible to use the Finite Element Method to determine if some upsetting operation will exhibit a free surface crack during a deformation process. In this study, a finite element program has been developed to analyze the deformation processes of sintered metals in upesetting. At the same time, products are inverstigated. The locus strains are then calualted and possible defects leading to material failure are checked. The calculated results argree well with the experimental results.

Blank layout is one of the most imporant processes in stamping die design. As the major cost in sheet metal stamping is te material cost, any efforts to minimise the scrap may result in substantial savings not only in strip material, but also in overall production. This paper is maily trageted at establishing a practical blank layou optimisation system forstamping die by using AutoCAD's ObjiectARX toolkit. The basic principles of blank layout optimistaion are first descrbed. Not only a suitable algorithm for layout calculation, but also the manufacturing requirements an user operation are fully considered in this system. Finally, an algorithm for blank shape offsetting is proposed to solve the problem of selfintersection in offset curves, andd the traditional' I-step translation' algorithm for the caluction of layout parameters is improved to eliminatte the confilic between preecsion and efficiency in the layout optimisation.

In the present paper, a 3-D rigid visco-plastic finite-element method coupled with void damage was developed for analyzing the fine-blanking process with an ineremental implicit algorithm. Based on the Gurwon Tvergaard-Needleman plastic peoteial equation and the orthogonal rules, the effect of of void volume fraction was introduced into the material constitultive law to document the ductile damage of the deformed material. A principle of variation of rigid visco-plastic material was presented considering both the shear work and the work caused by the cahange of vloume. This proposed principle revals both the effects of equivalent stress and bydrostatic pressure. The related FEM equations coupled with void damage based on this principle of ductile fracture in the blanking process. Based on the obtained system. the fine blanking process was simulated and the onset of the micro-crack of the sheet wais predicted. Furthermore, the influence of the studied work-piece shape on the deformation process was also discussed.

Based on the Curson-Tvergaard void damage plastic potential equation and by using orthogonal rules of plastic material, the influence of void volume fraction on stress and strain fields was introduced into Levy2Mises flow rules. The variation principle of rigid plastic material with void degradation was demonstrated. Furthermore, FEM equations coupled with damage factor were presented to study the void growth and the criterion to judge the damage was also given. Using the developed system, the fine blanking process was simulated and the sheared surface of the part edge was predicted. Meanwhile, the influence of process parameters, such as punch-die clearance, V-ring force, counter force, radius of punch and die edges, on the height and quality of the sheared surface was analyzed. The calculation results were compared with the experiments, which can be used to guide the design of fine2blanking process.

On the basis of the practical situation of cold forging process planning, the disadvantages of a rule-based solution are discussed, and a case-based reasoning-based cold forging process planning (CFPP) system model is proposed. Several key problems involved are analyzed, among which a feature-based part representation scheme and a two-level retrieval mechanism are introduced to solve the problems of case representation and case retrieval. It is established in this paper that case-based reasoning-based CFPP is a promising technology for both long-term research and the promotion of efficiency for current cold process planning systems. 2001 Elsevier Science B.V. All rights reserved.