Process Design And Numerical Simulation Of Hot Extrusion Forming For Deep Hole Parts

Hot extrusion is a kind of precision plastic forming technology, which is efficient,high-quality, and low consumption, to a great extent, it can realize near net shape,especially in the production of the stress components with complex shape, it not onlycan ensure the extrusion’s dimensional precision and mechanical performance, but alsocan reduce equipment tonnage and process. Therefore, the extrusion technology hasbeen developed quickly and widely applied to the precision plastic forming areas, suchas automobiles, machinery, military, aerospace, etc. When discussed hot extrusionprocess of the deep hole parts in this paper, the forging blank using other process,generally can’t achieve the dimension accuracy demand, in particular, it isn’t able todirectly forge the deep hole, requires a lot of cutting, that will not just destroy the metalstreamline density distribution, seriously affecting part quality, and excessive workingprocedures, low availability of materials and productivity. It is hard to meet to thedemand of low energy consumption, high quality and high efficiency, therefore the hotextrusion technology has become an important research direction in developing newtechniques of deep-hole parts.Hot extrusion is a complex system problem, the traditional physical experiment isdifficult to visually analyze the law of material deformation and flow, stress and straindistributions, it also unable to clearly explain the position and cause of material defectformation, the defect types and preventive measures. To optimize technology design,all we can do is only through a blind "trial and error method. Real-time simulation ofhot extrusion process within short period and low cost by finite element simulation,intuitively analyze internal mechanism of metal deformation, to provide theoreticalsupport for the optimization of process parameters and mold design, as a newtechnology and means of developing advanced techniques.Based on the hot extrusion process analysis of axle shaft sleeve, the two-step barforming process and one step pipe forming process are proposed in this paper.Establishment of the geometric model of mold and billet by CATIA, and then applyingthe finite element software DEFROM-3D to numerical simulate the new processes, through the single factor method, a set of optimum parameters, such as billettemperature, mold preheating temperature, friction conditions and extrusion speedprocess, were determined by comparative analysis of the four main parametersinfluence on the forming process. Simultaneous analysis of the regularities of metalflow velocity, stress-strain temperature and mold load in different process, it indicatesboth of the new technology can get ideal axle tube shape. Speed-reduction cylinders isdeep blind hole structure with flanged bottom. After completing the simulation analysisof one step hot extrusion process, it shows the extrusion meets the dimension accuracydemand. On this basis, the paper ultimately determine the optimal process plan, andcomplete the major hot extrusion dies design.Through this subject research of deep-hole parts, the extrusion theory and finiteelement simulation technology are integrated, which develops the new hot extrusionprocesses for axle shaft sleeve and speed-reduction cylinder. Simulation analysis hasverified the feasibility of technology, and for the similar parts, the results will providereference for the design of process and mold.