A Study of Shear Localization Chip Formation in Metal Cutting Process os An AISI 4340 Steel

• Main Authors: Lee, Kenneth, 李建成
• Other Authors: Scott Liu
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/00153758084387354462

碩士 === 國立中正大學 === 機械工程學系 === 85 === The shear localization phenomena during serrated chip formation in high speed metal cutting process have been studied by using the explicit finite element analysis. A three dimensional computational model has been developed for analyzing dynamic ther-mo-mechanical deformations of a thermally softening viscoplastic workpiece material subjected to various tool cutting speeds、tool rake angles and workpieces material hardness. The shear band characteristics such as effective plastic stress, effective plastic strain and shear banding angle are investigated for each cases. Cutting forces also can be estimated by this 3D model for the reason to reduce cost and time in experiment. The predictions of the finite element analysis are shown that above a critical high cutting speeds the Catastropic shear chip will be form due to shear localization in the primary shear zone and different kinds of cutting condition. The secondary shear zone of the chip on rake surface appear not to be a negligible effect which indicated the tool life during metal cutting process. Chip segments can be separated completely due to extensive shear in the primary shear zone; These phenomena during our metal cutting experiments in lathes agreed well with the experimental observations from literature so as to verify the accuracy of our numerical analysis. The numerical model presented here also applied to study the oblique cutting process.