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서원상(W.S.Seo),민병욱(B.W.Min),박근(K.Park),나승우(S.W.Ra),이상훈(S.H.Lee),김종봉(J.B.Kim) 한국소성가공학회 2010 금형가공 심포지엄 Vol.2010 No.11
Fasteners are used to join the various electronic products and machines. So, the quality and reliability of the fastener are strongly requested. In this study, the analyses of the multi-stage cold forging of TORX screws for storage parts are carried out. In manufacturing of TORX screws, crack and folding defects are observed. Therefore, the analysis is focused on the prediction of the defects. Also, the upper die and process conditions are redesigned to reduce the defects. The upper die shape for preform forming is redesigned to prevent folding and sharp shape change. The Cockroft-Latham damage criterion is introduced to predict the crack initiation. Analysis results shows that the maximum Cockroft-Latham damage value is decreased by 40% in the forming using modified upper die.