The Research Of Friction And Lubrication Chracteristics In Cold Extrusion Process Of Automobile Spline Shaft

The automobile spline shaft is an integral part of the overall composition. Its forming quality plays an important role in the normal operation of power system, the working stability, security and the working life of the vehicle. The method of cold extrusion process for spline shaft is better than the traditional cutting technology in the area of reducing the production cost of parts, improving parts’ quality and production efficiency. In this paper, the forming process of automobile spline shaft is analyzed systematically, and the friction and lubrication characteristics in cold extrusion forming process are also studied systematically. The full text research content mainly includes:1. Cold extrusion process of spline shaft. The material of spline shaft is CK45, and its geometry can be summarized into three parts: the cup wall, steps and external spline. With the finite element software DEFORM-3D, the cold extrusion forming process is analyzed including the overall deformation situation of parts, the flow of metal material, the influence of key process parameters on the punch load, and then the reasonable forming process program is concluded by using the orthogonal experiment. Final process: blanking— annealing — surface treatment — direct extrusion — cold heading — intermediate annealing and surface treatment—backward extrusion—normalizing—rough turning—gear burnishing- machining.2. The research of friction and lubrication of mould for cold extrusion. Firstly, the numerical simulation analysis of the wear of the automobile spline shaft bottom die in cold extrusion process was conducted based on the modified Archard wear model with DEFORM-3D, including the overall wear situation of the bottom die and the influence of key process parameters on maximum wear depth. Secondly, a new type of cold extrusion lubricants was configured in this paper based on the study of plastic forming lubrication theory and the existing cold extrusion lubricants. And then the lubrication effect was studied through the friction and wear tests, ring compression tests, the cold extrusion tests of the actual part and observation of the surface morphology of the formed part. A comparison was also made between cold extrusion lubricants used at home and abroad and the commonly used phosphorus saponification lubrication. Results show that, the lubrication effect of new lubricant is good, its friction coefficient is about 0.058 and can be used for cold extrusion process, which provide a favorable technical support for the actual promotion of lubricant for cold extrusion and further research.