• 소성∙가공
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• 제19권5호
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• pp.273-276
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• 2010

In this paper, back pressure forging processes of which back pressures are exerted by mechanical forces including spring reaction are simulated by three-dimensional finite element method. The basic three-dimensional approach extended from two-dimensional approach is accounted for. An axisymmetric backward and forward extrusion process having a back pressing die, which is exposed to oscillation of forming load due to variation of reduction ratios with stroke and its related frequent variation of major deforming region, is simulated by both two and three dimensional approaches to justify the presented approach by their comparison. A three-dimensional forging process having a back pressing die attached to the punch by a mechanical spring is simulated and the results are investigated to reveal accuracy of the presented approach.

• 한국정밀공학회지
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• 제14권8호
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• pp.57-64
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• 1997

The process design of backward and forward extrusion of axisymmetric part has been studied in this paper. The important factors of cold forging process with complex geometry are the design of initial billet shape, the possibility of forming by one-stage operation and the determination of preform shapes, etc. Based on the systematic procedure of process sequence design, the forming operation of cold forged part is analyzed by the commercial finite element program, DEFORM. The design criteria are forming load, geo- metrical filling without defect and a sound distribution of effective strain in final product. It is noted that one step of preform operation is required to obtain the final product. Numerical result is compared with experi- mental one. It is found that the analyzed result is in good agreement with actual forming result.