Numerical Simulation And Control Technology For Metal Cutting Burr Formation

Precision and super-precision manufacture, intelligent machining and automatic machining are key develop aspect of advanced manufacture technology. Burrs formation and variety directly affects the quality of work-piece and the efficiency of production. it's also one of the key technology of precision machining and automatic processing. Engineers and specialists all over the word pay great attention on burr formation mechanism and burr control.This study is based on the metal cutting burrs classification system of cutting motion and cutting edges of tools and the results of metal cutting at present. According to the theory of finite element methods, the models of burr formation are provided. The formation and variety of cutting direction burr, feed direction burr and two side direction burr are simulated based on software of DEFORM-3D and. DEFORM-2D. The basic law of burr formation and varity is found and simple prediction model is provided.(1) According to the theory of plastic, the finite element model of two side burr, feed direction burr and cutting direction burr are provided based on the metal cutting experiment. The formation and variety of burr are simulated based on software of DEFORM. The relation between the size of two direction burr and two direction strain is found. The influence of strain on finished suface and nature of chip material are investigated. The basic knowledge of control two side burr is provided.(2) According to the theory of plastic and the fracture criterion, the finite element model of fracture formation is developed and the processes of fracture formation are simulated and analyzed. The important factors which effect on size of cutting direction fracture are investigated. The basic law of fracture formation and varity is found. The relation between fracture and the crack formation and the growing direction of crack is found. The basic knowledge of control fracture is provided.(3) A viewpoint is provided about the realation between the rigidity of endpart and burr shapes switch. Based on the metal cutting burrs classification system of cutting motion and cutting edges of tools the important factors which effect on shape switch of primary burr and secondary burr are investigated. It's considered that the primary burr will be formed in final developed stage if the remaining material has no rigidity to allow cutting continually in final developed stage and secondary burr will be formed as the material has sufficient rigidity to allow cutting in this area around the tool tip. The rigidity of remaining part is one of the main factors that effect on shapes of feed direction burr.(4) The negative shear is found. It's found that the formation and varity of negative shear is a key factor that on shape switch of cutting direction/burr based on theory analysis and experiments. The formation and varity of negative shear region and shear region are investigated by theory and experiments and found that fracture and the crack formation in the arear near the tool tip and the growing direction of crack are important factor on shape switch of cutting direction/burr. The basic knowledge of control cutting burr/fracture and feed direction burr are provided.(5) The idears of active burr control are provided. Chamfering method, backup material mehood, superposition meyhod and other active control mothods are provided according to the fundamental principles to generate minimum burrs on the workpiece. The methods are investigated based on DEFORM software and then provides the most optimal cutting parameters or technical conditions. The essential of control cutting burr/fracture is control the negative shear and the essential of control two side direction burr is control two side direction strain. A solid foundation and experimental guidance for further improve the efficiency of controlling burr formation is set.The research and its production enrich and expand the theory of metal cutting and precision machining engineering, provide important technical and theoretical guidance for burr controlling and deburring efficiently. Research results can be used to precision machining, FMS and other automatic working widely, its application will bring remarkable economical and societal benefit.This research is supported by the National Science Foundation of China under the project No.50275066, No.50675088.and No.51005192.