| As the most important part of automobile for supporting load and driving,wheel hub units can support load and provide precise guidance to the rotation of the wheel hub,which is significant safety component of auto parts.With the development of era,the requirement of energy saving,high stability and low cost draw more attention.In accordance with these requirements,the changes occur in the clamping way of wheel hub units,such as the clamping ways are from the original nut clamping to the wheel hub units shaft riveting.At the same time,the wheel hub units shaft riveting technology that solves the problems regarding nut loosed and preload unloading and improves the stability and reliability of the wheel hub units gets a great performance in development and application.However,in our country,in the riveting process of the wheel hub units in automobiles,the crack easily forms in the flanging of wheel hub units,which resulting in the whole wheel hub units failure.So far,the domestic enterprises have not been able to produce the wheel hub units in shaft riveting assembly way,which becomes the technical bottleneck of wheel hub units manufacturing enterprises in our country.Based on the wheel hub units regarded as the research object,this paper carried out the study referring to the effect of riveting parameters and processing quality of wheel hub units as well as the effect between riveting parameters and shaft microstructure.The study mainly includes the following aspects:(1)Based on the theory of rotary forging,the principles and advantages of rotary forging process in wheel hub units,the macroscopic deformation mechanism of wheel hub units in the process of riveting was analyzed,which leads to the related parameters determined such as upper die tilt angle,descending speed and axial speed.(2)In accordance with the mechanism of rigid-plastic finite element method analysis,the simulation model of the riveting process in wheel hub units was built by Deform-3D.The shaft end shape before and after the riveting process,he stress nephogram and the forced location of the shaft were respectively obtained through simulating calculation.The relationship between the shaft end shape,inner race force and the upper die tilt angle,descending speed and axial speed was determined through this rigid-plastic finite element method analysis.(3)The experiment of the wheel hub units in riveting process is conducted,the related data was acquired and processed through data acquisition system.The relationship between the shaft end shape,inner race force and the related parameters such as upper die tilt angle,descending speed and axial speed was studied by contrast experiment based on single parameter.Therefore,the accuracy and validity regarding this finite element model of wheel hub units in riveting process was verified.(4)Microstructure of wheel hub units was analyzed after experiment.According to cracks in the shaft end,the shaft end of wheel hub units was divided into three areas.And then,the microstructure of these three areas in normal shaft end and three areas in cracked shaft end was respectively analyzed.Based on relevant references and researches in this field,the aspect ratio was built.At the same time,the relationship between the grain aspect ratio and the upper die tilt angle,descending speed and axial speed was studied.Finally,the microstructure of cracks in the shaft end was analyzed.Therefore,the experimental result of the crack microstructure in the wheel hub units shaft end was obtained. |
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