Formation Mechanism Study Of Serrated Chip In The Process Of Metal Cutting

Metal cutting processing is the most widely used processing method in the area of the whole machinery manufacturing, the high speed cutting has brought the entire manufacturing high precision and high efficiency and also meet the machining needs of the manufacturing enterprise. At the same time, in the process of high speed metal cutting, for most materials, it is easy to produce serrated chip, and then in the process, scraps of sawtooth facilitates the chip breaker, but the cutting force between the cutting tool and machining material will cause great impact and change, thus it will make the whole machining system or wave oscillation, which includes the unsteady directional vibration of the tool,what may damage or affect the service life of cutter tool, at the same time, the machined surface of material processing certain scope changes will follow. This not only affects the quality of the materials, also made the rising cost of machining efficiency lower. Therefore, in the process of metal cutting, the study of the formation mechanism of serrated chip in high speed metal cutting is of great significance to promoting the national economic and social development.In terms of serrated chip formation mechanism, distribution regularity of stress, strain, temperature, a lot of achievements laid a foundation for further study on cutting theory. But the problems of the relationship between chip sawtooth level and the processing surface quality need further studying or taking research. Therefore based on the theory of adiabatic shearing, we carry on the simulation of serrated chip formation process, comparing the simulation results under the different condition, to analysis the influence law of machining surface quality affected by the chip sawtooth level. Based on the theoretical analysis, experimental research and numerical simulation analysis, we take the 45 steel material as the research object, its in orthogonal cutting is serrated chip formation mechanism research. In this paper, the main research and innovation points are listed as follows:(1)To establish chip evolution law based on the basis of the theory of adiabatic shearing, take the orthogonal cutting experiment of 45 steel material research, improving gradually along with the cutting speed, the chip morphology is the continuous chip at the beginning, then turn into a serrated chip, at last, turn into fracture chip morphology. We also take meticulous observation of the surface of the chip, determine obvious difference between the continuous chip and sawtooth chip on the formation mechanism; After the serrated chip formation, the change of cutting speed and feed has essential influence to the sawtooth level of chip and the processed surface quality of the materials.(2)By using the finite element software of ABAQUS, we carried on the finite element simulation research on the 45 steel high-speed orthogonal cutting process. We obtained serrated chip formation mechanism by finite element analysis: workpiece material can produce thermoplastic instability under the condition of high temperature softening, then lead the material to the shear slip deformation in the deformation zone, resulting in a adiabatic shear band, lead to the formation of serrated chip. At the same time, combining with 45 steel high- speed orthogonal cutting experiment, in the case of guarantee the consistency of the change of cutting parameters, we compared the finite element simulation results with the experimental results, has a good result, From the research content and results of the comparison, we can know the root cause of the formation mechanism of serrated chip is due to the thermoplastic instability.