Papers by Keyword: Cold Heading

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Authors: B.H. Cao, John J. Jonas, P.R. Hastings, Nicholas Nickoletopoulos
Authors: Piotr Skubisz, Maciej Rumiński, Łukasz Lisiecki
Abstract: The paper presents selected aspects of analysis cold micro-forging process of a screw made of austenitic stainless steel, concerning relation between strain and hardness. Strain hardening character of a material in consecutive forming operations was analyzed experimentally by the measurement of hardness distribution made on longitudinal axial sections of screws. The relationship between hardness and effective strain (hardness curve) was determined, which made it possible to obtain strain distributions in different regions of a material subjected to cold deformation on the basis of strain distribution numerically estimated with FEM simulation performed using QForm2D/3D commercial software. Conclusions were formulated concerning strain inhomogeneity and strain-hardening intensity with respect to the correlation between strain and hardness. It was also concluded, that nonuniformity of hardening rate in a bulk can lead to local variations in flow stress and eventually, to occurrence of the metal flow related defects, which was illustrated with a case study of cold heading of self-tapping screw of AISI 304Cu stainless steel, with large head diameter to shank diameter ratio. In order to validate the obtained results, the same method was used for analysis of hardness development in steel 19MnB4.
Authors: Christine El-Lahham, James A. Nemes, Nicholas Nickoletopoulos, Michel Hone
Authors: Ying Ying Chen, Wen Jie Feng, Ying Yang, Yong Du
Abstract: This paper develops an opened forging and divided flow process for spiral bevel gears. By the help of rigid-plastic finite-element software DEFORM-3D, this paper designed cold-extruding part and concave die for bevel gear in the rear running gear of tri-motorcycle and simulated the forming process of cold-heading and extruding. On condition of guaranteeing shaping quality of teeth, the optimum diameter of die porthole was made sure by analyzing the effect of porthole size on volume of billet and plastic force. The experiment results show that the design parameter is reasonable and simulation results are helpful to the design of die.
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