Analysis and Experimental Study of the Composite Mechanical Bulging Process for Medium-Duty Commercial Vehicle Drive Axle Housing

A novel composite mechanical bulging process suitable for the manufacture of medium-duty commercial vehicle drive axle housings is proposed.The analytical expression for the limit bulging forming coefficient of tube blanks under conditions below the metal recrystallization temperature is derived, and the influence of the matching of various force parameters on the limit bulging forming coefficient is analyzed.The appropriate range for the axial auxiliary load during radial bulging is also presented.Based on the derived theory, a 5-ton commercial vehicle drive axle housing is selected as the research object.The key processes in the forming process are numerically simulated to obtain the metal flow state, stress-strain distribution, and wall thickness variation.The types and locations of defects that may occur during the bulging process are also predicted.To address the phenomenon of local wall thinning in the composite mechanical bulging process of the drive axle housing, a set of orthogonal simulation experiments is designed, focusing on the wall thickness thinning rate in the bridge arch bulging area and the crack-prone region, with respect to the process parameters.Based on the numerical simulation results, response surface equations are established for the expansion core's movement speed and axial auxiliary thrust in relation to the wall thickness thinning rate.Through parameter estimation of the response surface equation and regression analysis of significant influencing factors, the effects of process parameters on wall thickness thinning are obtained: the thinning rate in the bridge arch bulging area decreases with increasing expansion core movement speed and axial auxiliary thrust, while the thinning rate in the crack-prone region increases.The optimization of the response surface model and the determination of the optimal process parameter combination, based on field production conditions, show that the numerical simulation results and the wall thickness measurements from process experiments are in close agreement.No cracks occur in the axle housing, and the thinning is effectively alleviated.In contrast, mechanical bulging without axial auxiliary thrust leads to cracks, thus validating the feasibility of the proposed process scheme and the effectiveness of the parameter optimization.This research provides valuable technical reference for upgrading the manufacturing technology of large-span axle-tube products.