Study On Resistance Hot-driven Rivet-welding Connection Of Thermoplastic Polymer

With the rapid development of automobile industry, people propose new requirement on automobile: energy-saving, environmental protection and higher safety, which could achieve by reducing the quality of automobile. Therefore, the percentage of high-tensile steel, polymer materials, composite materials in the vehicle is bigger and bigger. And the reliable connection technology is the precondition of various kinds of materials used widely. At present, welding, bonding and riveting is the widely connection technology in electric appliance, airplane and automobile. Each technology has its advantages for different materials. The paper research a new method-- Resistance Hot-driven Rivet-welding for this trend, which could be used to connect the same or different materials.Resistance Hot-driven Rivet-welding: the rivet is powered and pressurized by pushing the two electrodes of resistance spot welding machine, forms securing rivet heads on both ends of plastic sheets and a melting zone of certain dimension at the joint included the characters of riveting、resistance welding and bonding. The joint has such property: implanted metal rivet lead to joint with high strength mechanical connection,simple operation process and wide range of application; the plastic surrounding rivet is melted by rivet heated during welding and bonded by electrode pressure, which could increase strength and fatigue resistance. Compared with the cold welding, metal rivet is heated to soften, the use of smaller pressure can achieve the same effect, so the method is economic, simple, fast and reliable, static strength of joint close to the parent materials.Using Resistance Hot-driven Rivet-welding connect ABS/ABS and ABS/Q235 with half hollow aluminium rivet. Experiment and optimize different process parameters to find the best process window. Design of data acquisition system based on Labview,gather the electrical signals of welding process at different stages and analysis the change of the temperature, dynamic resistance and deformation of rivet, divide the welding process into cold riveting deformation, hot riveting and stable deformation stages according to the measured data curve. Compare the difference between the theoretical value and the measured values by the analytical calculation, results show that the heating process is not only beneficial to improve the metal plastic, increase the rivet deformation,but also melt plastic materials and produce cementation between the contact interface of ABS/ABS and ABS/Q235; Comparing the influence of welding time and welding current on joint strength, find that welding current is more obvious effects on joint performance,the best welding current is 1.5k A. Analysis the tensile load and fracture curve underdifferent process parameters, the fracture mode of the highest joint strength is first bonding zone lamellar tearing, then plastic deformation, necking and fracture of rivet.Analyzing by photoelectron spectroscopy(XPS) and infrared spectrum, results that because of electric field and high temperature ABS is degraded, chemical bond is ruptured and C=O、C-O is generated by chemical reaction in the welding process, lead to the coordination bond at the atomic level of contact interface, enhancing the interfacial adhesion strength and significantly improving the joint strength; Using the finite element simulation software DEFORM, simulation analysis the temperature field, stress field,rivet deformation and fracture mode of ABS/ABS、ABS/Q235 joint in welding process,simulation results and the actual welding effect is almost the same.Experiments proved that Resistance Hot-driven Rivet-welding is a reliable connection method for the same thermoplastics, plastics and metal dissimilar materials.