Research On Precision Forming Process Of Multi-stage Warm-cold Extrusion For Outer Race Of Constant Velocity Universal Joint

Warm-cold compound precision forming technology makes full use of the advantages of warm extrusion and cold extrusion and it is widely used in manufacturing industry,especially in automobile part industry.Outer race of constant velocity universal joint is an important part of automobile.Due to the complex shape of the cup and the uneven thickness of the wall,it is difficult to produce.In this paper,multi-stage warm-cold compound precision forming technology for outer race is systematically studied through finite element analysis method,which provides useful guidance for process design and actual production.Through analyzing the structure and shape of outer race,Multi-stage warm-cold compound precision forming process was developed and the shape and dimension of billet and workpieces in every process was designed.On this basis,working parts of extrusion dies in every process was designed.By simulating warm forming processes,including forward extrusion,upsetting and backward extrusion,load-stroke curve and equivalent stress distribution of workpieces in every process were obtained.Influence of angle of concave die on forward extrusion,clearance between punch and die on upsetting were studied.The parameters of punch radius,punch angle and punch bearing length were tested to show the influence on backward extrusion.By simulating cold-sizing process,the collapse on end surface of workpiece was predicted.The influence of sizing amount,angle of concave die,extrusion speed and friction coefficient on collapse height and forming force was studied by orthogonal experiment,and a set of process parameters was obtained that makes collapse height and forming force smallest.In order to resolve the problem of underfilling of the inner cylinder surface of the outer race,the billet of cold-sizing was redesigned and the workpiece with sufficient filling of the inner cylinder surface was obtained.