Research On The Finite Element Simulation Of The Automobile Rear Axle Housing Mechanical Thermal Expansion

Automobile manufactory is the pillar industry of national economy in China .Recently years,with the rapid development of China's national economy, the automobile industry is also flourish. Microstructure and properties of vehicle have become the main contents of the current industrial research, which is from the whole body to various parts .It is no doubt that the heavy-duty axle commercial vehicle is one of the important parts. On the one hand axle plays a supporting role of car's load, what's more , axle is also a shell of automobile differential,main reducer and transmission. The quality of vehicle axle has a great influence on vehicle performance,therefore, effective optimization design of the axle housing is necessary. The research on axle is increased in-depth. Rear axle which has sufficient strength and stiffness should also have simple structure, low manufacturing cost, light quality, easy to dismantle and maintain.At present, there are two methods of manufacturing the axle housing of an automobile: one is casting and the other is stamping-welding. The casting rear axle housing of an automobile is the earliest structure adopted, which has the drawbacks of heavy weight, stringent technical requirements and casting faults that are difficult to control. Therefore the stamping-welding process is finding more and more application in manufacturing the rear axle housing of an automobile both at home and abroad. In using this method, a pair of upper and lower half housings are made by stamping steel plates into form, and then welded into one body. Alternatively, another kind of stamped-welded structure consists of right and left steel tubes, which are first machined into form separately and then welded together to become the axle housing. Although these housings are made of steel plates and welding work involved is relatively less they are still of welded structure. Compared with the cast structure, the stamped-welded rear axle housing of an automobile is light in weight. However, strict requirement is imposed on welding quality, because welding quality is critical to the quality of the housing. Therefore, sophisticated technology is involved and in most cases a special welding production line is needed, which takes a large fund to set up and hence the cost of the finished product.In recent years, research of the axle production process has hydro forming and mechanical thermal expansion. Which hydro forming is a new cold forming machinery,it mainly use liquid media as a load transfer,using liquid pressure to expand shell. From 20th century 90years,many industrialized countries have already started working on the using of hydro forming to produce automotive parts. The hydro forming of axle is mainly proceed to tube billet,the process is divided into two steps,the first step is to push compression tube billet, to make it's tip diameter composite requirements; the second step is expanding the middle part. The axle produce Ted through hydro forming process not only the utilization ratio is high,but also the production cost is low,with high strength and light weight. But the design of hydro forming process is based on accumulated experience and experiment to explore, which spend time and money, low efficiency.Mechanical thermal expansion is a new metal processing methods,which to some extent similar with the hot extrusion. In actual production,the expanding is mainly processed to tube billet,making a narrow straight opening in the middle of the steel tube along its axis, which the length of this opening being determined by the required diameter of the formed housing, i.e., The length of the opening being: such that it can be expanded to axle housing with the required diameter. Some methods needn't to put expansion cores into the tube billet,using mole expanding directly; while some other methods need to put cores into billet, then bulge cores by mold, to make cores move, and so to achieve the expansion of billet, which obtain the required shape and size of processing. In the hot mechanical thermal expansion processing need to keep heating the workplace, maintain a certain temperature, so the flow of easy-to-meta. Then we stress concentration is reduced, so that the quality of the work piece and the mechanical properties are protected. Using this processing method can not only improve efficiency and productivity of the billet, but also process the casting surface quality, high mechanical properties. This topic based on the theory of mechanical thermal expansion and the increase demand of automobile axle housing, which major research the center circle part; analyze the formation of bridge-shaped shell expansion process feasibility. Then we make process simulation. As the process parameters have great influence on the forming process and product quality, so it need to simulate different axle expanding process with different parameters, comparative analyze of the quality of products, to select the appropriate parameters, which provide theoretical guidance for the actual production.The hot mechanical thermal expansion of axle has just started,and the process is three-dimensional plastic forming, deformation complex, this will require the use of computer simulation technology. Finite element method as numerical analysis tools which has solid theoretical foundation and extensive application, not only overcome disadvantage of high cost and long cycle, and it can analyze more comprehensive the variation and relative relations of every quantum in processing, play an increasingly important role in the engineering.This paper researched the problem with the numerical simulation method, with the mature three-dimensional software (DEFORM-3D) to simulate the process of materials processing. Then we detailed in analysis of metal flow during deformation and the stress-strain law, which inferred the deformation characteristics by researching the velocity. At last we predict defects which may occur in the type and location and propose appropriate solutions. As the DEFORM-3D simulation software does not have the modeling capabilities, therefore it is need to use CATIA 3D modeling software to draw the geometric models, which will be used in the simulation process, even before the modeling in combination with the thermal expansion forming process and the actual production of the components involved in calculating size.