Study Of Critical Theory About Buckling Forming Of Middle Thick-walled Tube Bearing Axial Load

The need of high strength,lightweight and low cost is hastening the automobilestructure improving continuously. More and more parts are produced by reducingdeformation with middle thick-walled tube, such as transmission shaft,input and outputshaft,the top of veering shaft and the below of veering shaft and so on. For more andmore products structure updating continuously, it is the most power of manufacturing toadopt a low cost and high quality forming technique. The tube can form some parts ofdifferent caliber by the push-reducing deformation, and this is a key technology for highcapability,high strength and lightweight of automobile.When automobile parts are manufactured by the push reducing deformation withtube, must use an opening die. And the characteristic of forming is different betweenreducing and drawing deformation with tube. Many scholars have studied the drawingdeformation of the tube with core or without core theoretically. In 70's, some scholarshave analyzed the reducing deformation of tube without core systemically. And thiswork has promoted the development of the reducing forming with tube. The theory ofreducing forming has been perfected by a great deal of theory study work, and thistheory has come to maturity finally. But with the demand of precision about figure anddimension being higher little by little , the push reducing forming without core is goingto can't satisfy the need of manufacturing industry for its characteristic of forming. Sothe push reducing forming with core will be adopted to produce the products with highprecision at port of parts. However, when the tube deform by the opening push-reducingdeformation with core, the axial force will increase greatly. So the outstanding problemis the buckling forming of the passing power area of the tube. In fact, the axial carryingcapacity of the tube is littler than the rod, especially when the ratio of thickness andradius is very small. The key problem of processing is to calculate the critical load ofbuckling forming about the tube exactly。The buckling of middle thick-walled tube (D/t=20~80) bearing axial load virtuallyis elastic plastic forming. There are two primary buckling formats: global buckling,local wrinkling. It is also resolved urgently that which buckling format will occur fordifferent geometry parameter. Moreover, need to deduce the relation of the critical loadbetween global buckling and local wrinkling, and also to conclude the critical lengthbetween global buckling and local wrinkling in order to resolve the problem of addingmiddle support on the long pipe.In this paper, it is first to put forward the method of using die with floatingcore-axis to decrease the axial extrusion force of reducing deformation with middlethick-walled tube. Furthermore, we have manufactured transmission shaft in car...