Research On Multi-process Of Precision Warm-cold Forging For Tulip Outer Race

The warm-cold forging technology can convert the blank into high value-added productions. And this technology combines the advantages of both warm forging technology and cold forging technology. Hence the warm-cold forging technology represents an important direction of the development of the precise forming technology.The tulip outer race is an important component of the tripod constant velocity universal joint. And the cup part of tulip outer race is deep inside with a high requirement of surface accuracy and dimensional accuracy. Currently, the tulip outer race is produced through warm-cold forging technology in developed countries. With the rapid development of the automobile industrial in China, demand for tulip outer race is getting huger. Hence, in order to improve the production efficiency and reduce the production cost, the research in the production of tulip outer race with warm-cold forging technology has a very important significance.In this paper, after the comparison of the forming process and results of two kinds of warm preforming plan, the three step warm preforming plan is considered to be the suitable plan for the production of tulip outer race. In the three step warm preforming plan, height difference of end surface, collapse length of end surface and load are chosen as indicators to measure the quality of tulip outer race in the warm preforming process. With the help of 3D FEM simulation, the influence laws of friction coefficient, extrusion speed, top die radius, top die bearing length, top die angle on the forming quality of tulip outer race are obtained. By means of preforming design of the blank and the structure change in top die, the tulip outer race get a better quality.By means of orthogonal experiment of the cold sizing process, with the load and the maximum gap value in between surface of top die and inside surface of the cup of the tulip outer race as indicators to measure the quality of tulip outer race in the cold sizing process, the influence laws of shell radius of tulip outer race, sizing amount, angle of concave die, friction coefficient, extrusion speed on the forming quality of tulip outer race are obtained. And the best combination of the forming parameters are given.Using 3D FEM simulation, the elastic deformation of top die and the elastic recovery of the blank in the cold sizing process are obtained. And according to the dimension compensation theory the elastic deformation of top die and the elastic recovery of the blank are compensated to top die to realize the precise design of top die.