Study On The Critical Transformation Of Cutting-direction Burr/fracture Formation And Controlling Technology

The formation of burr is a common phenomenon in metal cutting,its fomation and variety directly affects the quality of workpiece and the efficiency of production. It is one of the key technologies of the precision or super-precision and automatic processing.According to the metal cutting burrs classification system of cutting motion and cutting edges of tools,based on orthogonal metal cutting test,this dissertation systematically expands the researches of the formation of cuttingdirection burr/fracture and the critical transformation law with the finite element method.The main contributions are summarized as follows:1) This paper systematically expounds the elementary theories and solutions of metal cutting burr finite element modelling.The research regards orthogonal cutting as study objects,based on chip separation criterion with damage effects,the finite element models of metal cutting burr formation are generated in ABAOUS/Explicit,the results demonstrated that the models are reasonable and valid.2) In terms of the finite element models of metal cutting burr formation,this paper reveals systematically the progress of cutting-direction burr/fracture formation and change laws.Based on metal cutting experience,the main factors that influence cutting-direction burr shapes and sizes are analysised,elementary forecast or prediction for metal cutting burr is carried out.3) The varieties of stress and strain of material that inside workpiece in the formation of cutting-direction burr/fracture are studied in depth,it points out that the formation and variety of negative shear region is an important reason for burr/fracture transformation,Presents the critical conditions and the basic laws for cutting-direction burr shapes switch.4) According to the fundamental principles to generate minimun burrs on the workpiece,the action and effect of backup material and other methods of initiative control cutting burr formation are studied with FEM,then provides the most optimal cutting parameters or technical conditions,and sets a solid foundation and experience guidance for further improve the efficiency of controlling burr formation. This research is supported by the National Science Foundation of China under the project No.50205066 and No.50675088.The research achievements enrich and expand the theory of metal cutting and precision machining engineering,its application will bring remarkable economical and societal benefit.