Research And Development Of Crack Detection System For Cold Riveting Of Automobile Hub Bearing

With the rapid development of industry,the automobile hub bearing has developed from the first generation to the fourth generation,while the third generation is a relatively common type at present.Compared with the previous automobile hub bearing,the third generation of bearing ring has added flange plate outside,and adopts riveting assembly process,which not only improves the bearing performance,but also puts forward higher requirements for bearing riveting process technology.Due to the slag inclusion,heat treatment process and wear of rivet head,cracks will be produced after riveting,which also puts forward additional requirements for bearing quality inspection.Therefore,it is necessary to carry out crack detection for riveted bearings.At present,artificial visual inspection is often used in crack detection,which is not conducive to automatic production.Aiming at the crack problem of the third generation automobile hub bearing riveting,this paper puts forward the detection method of crack based on eddy current principle,and studies the process of riveting and eddy current of crack,determines the appropriate eddy current detection parameters,and develops eddy current crack detection machine for hub bearing.The main contents of this paper are as followsThis paper takes the third generation hub bearing as the test object,simulates the stress in the riveting process of automobile hub bearing based on finite element method,and uses Deform analysis software to simulate the stress in the riveting process and the position where the probability of cracks is the greatest,which provides guidance for the installation position of bearing eddy current detection probe;furthermore,it uses Ansoft Maxwell,an electromagnetic analysis software,to simulate the bearing in the eddy current.The influence of eddy current probe diameter,lift-off height and excitation signal on the eddy current distribution of bearings is obtained by simulation analysis of the flow detection process.The results show that different influencing factors can provide theoretical guidance for the selection of eddy current simulation analysis parameters.Based on the analysis of riveting crack characteristics and the influence of eddy current parameters,the whole mechanical design and eddy current detection system of automobile hub bearing crack detection device are designed respectively.The mechanical system mainly includes the structure design and working parameters selection of hub bearing eddy current testing machine,bearing rotating lifting device,eddy current probe installation mechanism,defective product rejection mechanism,etc.At the same time,the eddy current detection system for cold riveting cracks is designed from hardware circuit and software respectively.The hardware circuit design is divided into power module,analog circuit and digital circuit design.The design of software system includes the design of main interface and control interfaceFinally,the eddy current crack detection machine for hub bearing is assembled and debugged,and its effectiveness is verified by on-line testing of four different types of cracks.The test results show that the developed automobile eddy current detection system can effectively detect the cracks in riveting process and meet the requirements of bearing crack detection.At the same time,the loading and unloading mechanism of the wheel hub bearing crack detection device can realize the purpose of online automatic detection,which ensures the quality of detection and reduces the labor cost and intensity of workers.