Research On Force And Heat Calculation Method And Its Application Of Gear Slicing Based On Chip Geometry Model

Gear slicing technology is a brand-new gear machining technology realized in the21 st century.It has the advantages of continuous,high efficiency and high precision.However,the technology has not been widely applied in the field of gear machining until now.The main reason is that the cutting mechanism of gear slicing is unknown.At present,the tool design method based on conjugated rotary cutting principle is relatively mature,but the designed tool exposes the problem of premature failure caused by serious local wear in actual production.Therefore,it is urgent to carry out the research on the cutting mechanism of gear slicing.During the cutting process,there is an instantaneous contact area among the tool,the workpiece and the chip.The speed and rake angle of the cutting edge point in the area fluctuate greatly,so that the thickness,width and area of the chip have time-varying nonlinear characteristics.The variable force thermal load fluctuates greatly,and the local wear is severe,resulting in a serious shortage of tool life.Therefore,it is urgent to carry out in-depth research on the cutting mechanism,and to prove the generation mechanism of cutting force and cutting heat considering the instantaneous crosssectional shape of the chip in the case of the time-varying intermittent multi-edge incremental forming characteristics in the dry cutting process,so as to provide mechanism support for the design of cutting tool.In this paper,starting from the modeling of cutting chips,the calculation method of cutting force and cutting heat is studied,and the multi-objective optimization method of cutting process parameters is studied from the perspective of mechanical and thermal optimization.The chip shape directly reflects the changes of cutting force and cutting heat acting on the edge area during the cutting process.On the basis of analyzing the chip formation in the cutting process,the edge sweep and edge sweep family models of the cutting tool are established.Through the intersection of the machined tooth surface,the tooth surface to be machined and the edge sweep surface,the flattened chip geometric model is obtained,and then the calculation formula of its key geometric parameters is deduced.We carry out cutting processing experiments,compare and analyze the flattened chips and actual chips,correct the instantaneous cross-sectional size of the flattened chips,verify the correctness of the improved geometrical model of the flattened chips,and provide an effective tool for in-depth analysis of cutting force and cutting heat.Cutting force is an important factor affecting machining phenomena such as cutting vibration and tool wear.Establishing its analytical model is helpful for in-depth understanding and analysis of the cutting mechanism.Taking the micro-element area of the flat chip section as the instantaneous cutting layer of the micro-segment of the cutting edge,using the Kienzle-Victor theoretical formula,and through the discretization modeling idea of integral cutting tool and the superposition and conversion of cutting force vector,a calculation model of cutting force with wide applicability is constructed.Taking the cutting process of a certain type of needle housing as an example,the precise calculation method of cutting force proposed in this paper is used to obtain the cutting force and total cutting force in the three directions during the machining process,which are compared with the measured values of cutting experiments to verify the accuracy of the theoretical model and effectively predict the cutting parameters under different cutting parameters and the cutting force.Through the range analysis of the orthogonal experiment,the influence of cutting parameters on the cutting force is discussed.In the process of cutting material removal,the generation and dissipation path of cutting heat are also important factors affecting practical problems such as tool wear.It is an important link to explore the cutting mechanism to study the calculation method of cutting heat in tooth cutting.On the basis of analyzing the cutting processing characteristics of the cutting blade,the teeth of the cutting blade are divided into several parts along the cutting edge,which are called micro-segment teeth.Combined with the micro-element characteristics of the flattened chip section,comprehensively considering the cutting speed,chip force,tool-chip contact friction and cutting temperature in the cutting process,a calculation method of the cutting process of the cutting tool is proposed.The influence law of each cutting parameter on the tool temperature is analyzed.In actual production,since the force/thermal state of tooth cutting processing is not yet clear,the cutting processing parameters are usually set by workers’ experience in engineering,which brings about the problem of short tool life.It also cannot give full play to the advantages of high efficiency of tooth cutting.Combined with the cutting force and heat calculation models mentioned above,the correlation between the force and heat load of the cutter teeth and the wear of the rake face is discussed.Using the results of orthogonal experiments as training data,the neural network parameters were optimized by genetic algorithm to establish a mathematical model between cutting parameters,cutting force and tool temperature.Then,aiming at reducing cutting force,reducing tool surface temperature and improving machining efficiency,a multiobjective optimization model is established,and the second-generation Non-dominated Sorting Genetic Algorithm II(NSGA-II)is used to carry out the analysis.Then,according to the actual processing requirements,the Pareto optimal solution is determined through the screening function to realize the optimization of processing parameters.By comparing the test data and the optimization results,the effectiveness of the optimization model is verified,which provides an effective means for future wear control.