Research On The Key Technology Of Cold Precision Forging Near-net Shaped Forming Process For Multi-Steps Short-Shaft

"Near-net forming technology" is a kind of parts forming technology, through which the formed parts can be used as a mechanical component after only a small amount of machining process or no machiningprocessing.It has promoted the traditional forming, and making the formed mechanical components with precise size, accurate shape, lower surface roughness and other characteristics. Cold precision forming technology is an important technology in the field of near-net shape, which has been used in the manufacture of near-net forming parts. The vehicle shaft parts has the characteristics of small weight and multi-stepsetc., it is suitable for cold precision near-net forming. In this thesis, in view of the development of the vehicle parts manufacturing technology, a certain type of trailer short-shaft was used as the object of study to carry out the research of such short-shaft.First, The development status of cold precision forging near-net shaped forming at home and abroad was studied in this thesis; and the feasibility of forming multi-stepsshort-shaft by cold precision forging near-net shaped forming technology was analyzed,the technical difficulty and key technology of the process was obtained through the analysis, and the cold precision forging near-net shaped forming process of multi-stepsshort-shaft has been preliminarily designed; based on feasibility analysis, extrusion forming and upsetting forming of the first two processes were simulated and analyzed by using the metal forming finite element simulation software DEFORM-3D,the forming process, the stress distribution and the change tendency of the forming force of the first two processes were obtained; according to the design ofthe third shaping process and the fourth sizing process, the key technologiesresearch of the ironing cone cold reshaping and high precision dimension forming and maintaining have been done through the numerical simulation and experiments, the feasible reshaping process parameters and the key technologies of high precision dimension forming and maintainingwere obtained.Finally, it was determined that the multi-stepsshort-shaft can be formed through four cold precision forging near-net shaped forming processes such as extrusion, upsetting, reshaping and sizing, and the process diagrams of four forming processes were drawn, the complete cold precision forging near-net shaped forming production process of multi-stepsshort-shaft was designed. At the end of this thesis, in order to verify the results of the previous research and the process, the cold precision forging experimental process of the multi-stepsshort-shaft was designed, the dies of four forming processes were manufactured, and the experimental research was done after the pressure equipment were selected. The results of the cold precision forging experimental processverified the research results in front of this thesis, the experimenthas already formed the multi-stepsshort-shaft precision forging with good shape and qualifieddimension. According to the research results and process, all dimensions do not need to be machined in addition to the threaded part of the small end, near-net shaped forming of the part has been realized.Through the research of this thesis, we provide a complete set of multi-steps short-shaft near-net shaped forming technology and key technologies, which enrich the theory of near-net shaped knowledge, the research results and process play a guiding role for the actual production.