Research On Forming Process And Key Technologies For Manufacturing Integral Driving Axle Housing Of Commercial Vehicle

The driving axle housing is the installation support of the vehicle driving axle transmission system.It plays bearing and force transmission role in the process of vehicle driving,which requires high mechanical behavior.According to the shortage of the manufacturing technology of thick wall driving axle housing and the development tendency of automobile lightweight,a new type of forming technology for manufacturing the integral driving axle housing of commercial vehicles is proposed.With the new technology,the housing is made of seamless steel tube after several working procedures include necking both ends of the tube,reshaping the inwall and the lute hole expansion process.Compared with the traditional manufacturing technology of the driving axle housing,the new forming technology can significantly reduce the weight of driving axle housing and the influence of the welding seam on the performance of product so that the bearing capacity of the driving axle housing will be greatly improved.In addition,the process of the new forming technology is more simplified.In this paper,the process flow of manufacturing the integral driving axle housing of commercial vehicle with seamless steel tube is introduced in some detail,and the innovative design of forming methods for manufacturing the shaft heads and the lute hole is put forward.From the aspects of theoretical analysis,numerical simulation and process experiment,the paper further explored the key forming processes.The deformation mechanism and the influence of process parameters on the formability of metal are researched so that the forming process theory of manufacturing the integral driving axle housing is further improved.For the sake of forming the shaft heads of the driving axle housing,the paper puts forward two methods,pushing necking with pulling reshaping cores and pushing necking with machining respectively.The mechanical models of pushing necking and pulling reshaping cores have been given,theoretical analysis with regard to the ultimate load of the pushing necking and pulling reshaping cores processes has been conducted by taking advantage of upper bound method.Based on the proposed technology for bulging the lute hole,the infliction criterion of the auxiliary thrust is analyzed and determined.According to the condition of metal plastic deformation and the constitutive relation of material,the expression of limit expansion forming coefficient below the recrystallization temperature of the material is deduced.In addition,the influence law of the force parameters matching on the expansion forming coefficient is studied as well.Finite element simulation of the integral driving axle housing of 9T commercial vehicle is conducted to obtain the metal flow condition,the stress and strain distribution and the change regulation of the forming load,and the influence of key process parameters on the formability and forming load is studied.Through the intelligent control method,the process parameters of the lute hole expansion process are optimized.Based on the forming process of the lute hole expansion of 5T commercial vehicle,the stress and strain of a reference point in the region prone to crack in the bulging process are analyzed,different auxiliary thrust loading moments are worked out and the corresponding numerical simulations are carried out,and the optimum time range of axial auxiliary thrust loading is researched.In order to validate the key technology of the integral driving axle housing forming process of commercial vehicle,the tube necking experiment for manufacturing the inner step-shaft of the driving axle housing of 9T commercial vehicle and the radial expansion experiment for the lute hole of the driving axle housing of 5T commercial vehicle have been carried out.The results of the shaft head forming experiment show that the wall thickness distribution of seamless steel tube after necking is consistent with the numerical simulation,and the cutting demonstration shows that the thickness of the shaft wall after necking fully satisfies the machining requirement.The expansion experiment has verified the important role of the axial load in improving the formation of the lute hole and the influence of different loading time of the axial auxiliary thrust on the expansion effect.The wall thickness distribution of the expanded region after experiment is consistent with the numerical simulation,which proves the correctness of the derived theory of mechanical expansion and numerical simulation.Moreover,the experimental results also show that the deformation caused by the radial motion of the expansion cores is the necessary condition in the mechanical expansion process for the lute hole.Moreover,the design of the key forming mechanisms in the forming process for the integral driving axle housing of commercial vehicle provides an important basis for the formation of the integral axle housing forming technology and the realization of the mass production of the product.