Study On The Optimization And Safety Countermeasures Of Self-pressing Rivet Joint Technique

Since the 21 st century,the automotive industry has maintained a strong development trend,and the requirements of people in automotive performance are constantly improving.How to reduce the body weight on the basis of guaranteeing high quality connection is a long-standing problem for manufacturers.At present,a large number of practical studies have proved that the most effective way to achieve lightweight body and reduce exhaust emissions is to use light materials,such as aluminum,plastic,etc.Up to now,spot welding is still the most commonly used method to connect the structure,but this method has some defects and shortcomings,which is not suitable for black metal or non-ferrous metal,metal or non-metal joints.But today,with the rapid development of automobile industry,to improve production efficiency,to ensure the welding quality of parts,to make up for the shortcomings of spot welding and to realize the true sense of automation production,a new welding method is needed,and riveting has been widely concerned and favored by automobile manufacturers since it came into being.In this study,based on the theory of self-piercing riveting,the relationship between the process parameters of self-piercing riveting of semi-hollow rivets and the safety strength of the joints is emphatically analyzed by the combination of numerical analysis and experiment,and through upgrading the riveting process and optimizing the process parameters of riveting of semi-hollow rivets,the riveting pairing of semi-hollow rivets in the riveting is studied.A set of scientific and reasonable safety for strategy riveting process is put forward to minimize some potential hazards in the process of production,and the author provides a reference for production and processing enterprises.Firstly,the author simulates the process of self-piercing riveting with finite element software Simufact.Forming to introduce the simulation process and parameters of semi-hollow riveting in detail,and so as to verify the feasibility of this technique.Secondly,the author selects appropriate process parameters and are analyzes the effects of various parameters on the quality of self-piercing riveting through the simulation.The parameters are the angle parameters of rivet pin,the height of punch and the riveting speed of machine.Finally,riveting experiments were carried out on rivets with different pair values,and tensile and tearing specimens were made.The riveting specimens of different parameters are tested with universal capability test machine.The experimental results were compared with the simulation ones.The results show that the bottom thickness and the residual thickness also have an effect on the tearing force of the specimens.As the increase of the height of convex platform,the bottom thickness and residual thickness become thinner,and the strength of the lower sheet decreases,which will lead to the failure of the rivet inner sheet easily,like falling off.The bottom thickness and residual thickness are also important criteria for the strength and quality evaluation after riveting.According to simulation and riveting experiment results,it shows that there is a certain gap between rivet cover and sheet metal after riveting.Therefore,this paper also proposes a composite riveting device for preliminary exploration to solve the problems of single internal lock structure of traditional semi-hollow riveting and to rivet possible gap after completion,so as to solve the problems in the connection the plates with higher strength.