Simulation And Cutting Experiment Of Electric Hot Machining

Electric Hot Machining (EHM) is an efficient method to improve the machinability of difficult-to-cut materials, obtain better surface quality and reduce tool wear. Researchers have studied this cutting technique for many years, however, the study on cutting force and cutting temperature which is significantly important to the mechanism of the EHM, has been paid little attention. So the context in this paper shows as follow:1. Heating resistance. EHM primarily relies on heating resistance to quickly heat the material in the deformation area, therefore the studies on the generating mechanism, components and empirical equation of the heating resistance are valuable for analysis on the mechanism of the EHM. Based on the electrical contact theory and the characteristics of EHM, a 3D model of heating resistance is established in this paper. And the empirical equation of cutting parameter and heating current to the heating resistance is given by the precious measurements of the heating resistance, which can accurately represent the change law of resistance under certain conditions.2. FEM simulation of the EHM. The simulation of EHM process is of great significance in the optimization of experimental parameters, the cost saving of prdduction and the incensement of efficiency. This paper seems the exotherm caused by the heating resistance as the initial temperature of the workpiece, uses Umbrello constitutive relation related to the hardness of material to describe the flow stress, and then simulates the EHM process using the FEM software DEFORM. According to the simulation results, this paper predicts the cutting force and cutting temperature in the EHM process. In order to verify the accuracy of the FEM model, this paper measures the cutting force when EHM GCr15 bearing steel of HRC60 with YT726 Carbide cutting tools. The comparison shows that the simulations have well agreed with the experimental results with small relative error, concerned the system error and the measurement error, FEM model built in this paper is accurate. After verifying the accuracy of the FEM model, the optimum heating current can be obtained based on the simulation results of the cutting temperature and the optimum cutting temperature conservation law.3. Dimensional error in EHM.EHM raises the temperature in cutting zone to improve the machinability of difficult-to-cut materials, meanwhile, high temperature causes distortion of workpiece and tool, affects the dimensional precision. This paper chooses slender shaft as workpiece, optimizes the experimental parameters, and then analyzes the dimensional error. The tests show that dimensional error is caused by both cutting force and cutting temperature. Heat distorts workpiece, affects the actual cutting depth. Meanwhile, heat softens the workpiece, reduces the cutting force, and thus reduces distortion which is beneficial for reduction of dimensional error.