Research On Effect Of The Tube Thickness Deviation On The Bulging-crushing Deforming Axle Housing

Bulging-crushing production process is a new technology to produce automobile axle housing. First a seamless steel tube in appropriate size is selected, then a preformed tube is obtained after twice necking and once hydro-forming, finally, the performing tube is filled with liquid and pressed with dies in order to get an axle housing sample. The sample is of reasonable thickness distribution and advantages of no welds and high strength. Currently in the development of the axle housing bulging-crushing deforming pressure, the initial tube is regarded as a uniform wall thickness of seamless steel tube. However, there is actually a thickness deviation which has an effect on the bursting or wrinkles in the process of the bulging-crushing. Therefore, the thesis aims to explore the effect of thickness deviation on the bulging-pressing forming axle-housing, and try to find a reasonable range of the tube wall thickness deviation, thus help to highlight the significance the selection of the initial tube and the actual production of tubes.By probing into one medium truck’s axle housing, this thesis introduces the process of hot rolling seamless steel tube production, makes the explicit initial tube tolerance, establishes the geometrical model of the initial tube wall thickness deviation and divides test groups on the basis of thickness deviation coefficient. Moreover, the study simulates the necking of the initial tubes with different thickness deviations by using ABAQUS finite element software to seek the thickness distribution and the equivalent stress-strain of initial pipe with different wall thickness deviation, thus to find the influence of the initial tube wall thickness deviation on thickening rate in the process of extruded sinking.Through simulating the bulging-forming process of the tube after the extruded sinking process, the study makes an analysis of the effects on the bulging-housing formability, the thickness distribution and the equivalent stress-strain of the tubes with different thickness deviation and finds the influence of different wall thickness deviation on reduction rate of the front cover and the rear cover in the bulging process. The study mainly focuses on the situations of bursting or wrinkles and choices of suitable tube of the bulging formability to find out the preliminary range of deviation coefficients.By simulating the pressing process of bulged tubes with good formability, the study makes an analysis of the wall thinning rates of the front cover with different thickness deviation and the possible depression of the straight arm to find the influence of different wall thickness deviation on reduction rate of the front cover in the pressing process and choose the suitable tube of the bulging formability to ultimately make the explicit rang of thickness deviation of initial tubes.