Study On Self-Piercing Rivet Of Aluminum Alloys Of Automobile Body

The lightweight is automotive manufacturers the current and future development focus and theme,while automotive steel was used by car which is no longer applicable to the theme,must develop light alloy and other advanced materials,for example aluminum alloy,magnesium alloy and carbon fiber materials etc..The application of aluminum by automobile is facing many new technical problems,the traditional automobile manufacturing assembly process joint for aluminum alloy and other light alloy is very difficult.Self-piercing riveting(SPR)is a join method of cold forming,can join aluminum alloy and other material by a reliable connection,however,Research and application of SPR technology have made preliminary progress in China manufacturing industry,there are many parameters affecting the quality of the SPR joints,but the degree of influence of each parameter on joint quality remains to be studied.In this paper,AA5182-O aluminum alloy with thickness of 2mm was used as the research object of SPR test with semi-hollow rivets,optimize the parameters by orthogonal design method,and the die shape(flat die A,convex die B and C)have influence on the mechanical properties of the SPR joints is analyzed,the fatigue of self-piercing riveted joint was investigated and the mechanical properties of between self-piercing riveting and resistance spot welding are compared.Main contents are as follows:(1)The AA5182-O+AA5182-O Aluminum Alloy as experimental objects,taking orthogonal design method,the die shape,clamp pressure and setting pressure as three factors,the experimental data(interlock,under different parameters,bottom thickness rivet spreading,lap shear and cross tension)of self-piercing riveting joints is analyzed through range method and variance method.The test shows that,the setting pressure is the most influential factor among three factors,but is not and self-correlation;and die shape is not influential as the setting pressure,die bump height was found to be inversely proportional to the interlock.Die shape has significant influence on the lap shear strength and cross tension strength.On this test basis,the best process parameters were obtained.(2)The effects of different die shapes on the mechanical properties of the SPR joints were studied under the same clamp pressure and setting pressure.The stability of lap shear and cross tensile strength was among the three different dies,the platform die is the best.The hardness of the material around the rivet is the largest,and the die C has the greatest influence on the deformation of the aluminum alloy plate by the hardness test of the joints under three different dies.(3)The fatigue tests of SPR joints were carried out.The results showed that three types of fatigue failure modes of rivet pullout from the top sheet,the bottom sheet fracture and the top sheet fracture.(4)Mechanical properties between resistance spot welding and SPR was compared under the same Aluminum Alloy sheet,it was found that the lap shear strength,cross tension strength and peel strength were stronger than the spot,each strength is 1.27 times,1.37 times and 1.68 times strength of spot welding.Moreover,the energy absorption of the SPR joint is higher than that of spot welding,the SPR joint is more toughness.