Development For The Near-net Plastic Forming Process Of Conjunction Gear Based On Numerical Simulation And Research On The Design Of The Die Set

With the continuous development of Chinese automobile industry,the demand for coupling teeth is increasing,and at the same time,the quality and precision requirements of coupling teeth are constantly improving.There is a certain gap between our country and foreign developed countries in the forming technology of combined gear.Foreign countries use precision forging forming technology to manufacture combined gear,while some enterprises in our country still use the traditional method of welding after machining.Compared with precision forming technology,the traditional method has low efficiency,poor organizational performance and short service life,making it difficult to meet market needs.It is a secret that precision forging technology can be used at home and abroad,and all the technology has not been disclosed yet.Many domestic scholars also study from some processes of combined gear.The complex structure of the joint teeth leads to its high forming difficulty and requires multiple processes to complete the production of the product.Compared with hot precision forging,warm precision forging overcomes the problems of surface quality deterioration and dimensional accuracy reduction caused by oxidation in hot precision forging,and the die life is significantly improved compared with cold precision forging.Warm precision forging has the advantages of cold precision forging and hot precision forging,so this article mainly studies the use of warm forging to form gear blanks.In this paper,the process plan is determined based on the combined tooth parts drawing,the research goal is formulated,the hot die forging drawing is designed,and a number of comparative experiment schemes are designed based on the hot die forging drawing.Through the numerical simulation technology and deform software,the finite element analysis is carried out from different skin connecting positions and pre forging structures.The forming effect shows that the combined tooth forging drawing is not suitable for setting the connecting skin position at the bottom.At the same time,the pre forging structure is too simple to fold and cannot play the role of pre splitting.Then,the comparative study was carried out from the die forging modes and extrusion methods,and the forming effect,forming load,equivalent stress and strain,die wear of each scheme were studied and compared respectively.Finally,the ideal scheme of forward extrusion forming of closed die forging was found,and the structure of pre-forging parts was optimized.Three process parameters,billet heating temperature,die preheating temperature and forging speed,were selected to study their influence on the forming load.Nine groups of experiments were carried out according to the orthogonal experimental method.It was determined that the optimal process parameter combination should be billet heating temperature 900 ?,die preheating temperature 350 ? and forging speed50mm/s.After optimization,It is found that the forming load is lower than other schemes,which proves the feasibility of the optimization scheme.The numerical simulation of the key process of gear forming process is helpful to reduce the cost of research experiment,shorten the research cycle and improve the efficiency of research.Compared with turning,precision forging can reduce material cost and improve material utilization.In this paper,according to the hot forging die diagram,the required blank size is calculated.Through theoretical calculation and the actual needs of the company,the punch and die structure or upper and lower die structure for final forging,pre forging and pier roughing as well as the combined die cavity structure convenient for blank removal are designed.According to the closing height of the hot die forging press in the factory,the final die base structure diagram is calculated from bottom to top,including the base plate,each process mold,cushion block,ejector bar,guide post and guide sleeve,etc.According to the actual demand,the material and heat treatment requirements of the main parts are determined,and The mould and the mould base were manufactured and assembled.