Mechanical Engineering Journal (May 2023)
Development of joining technique for steel/fluororesin based on resistance heating
Abstract
Dump trucks are widely used in the construction industry. When sand is discharged from a dump truck bed, the friction with the bed causes sand to remain on the bed. Therefore, it is desirable to develop a technology to adhere low-friction fluororesin to the steel plates of a truck bed. This study develops a technique for directly joining dissimilar materials, namely steel and polytetrafluoroethylene (PTFE), using one-sided seam welding and investigates the effects of heat input and pressure conditions on joining quality. The joining conditions that affect joining quality are examined. The results show that tensile shear strength tends to increase with increasing heat input. Furthermore, it is found that the amount of PTFE deformation and the fracture morphology during tensile testing change with roller pressurization. For a one-sided seam welding machine, the anchor effect occurs between the electrodes with roller pressurization but does not occur without roller pressurization. It is also found that the type of anchor effect (dense or dispersed) depends on whether roller pressure is applied. Furthermore, it is suggested that the amount of deformation of PTFE during tensile testing is different caused by the different form of occurrence of the anchor effect. It was assumed that the fracture morphology of PTFE changed as the amount of deformation increased during the tensile test, approaching the elongation limit of PTFE. Furthermore, when the rollers were cooled to increase the cooling function of the rollers, the number of anchors was found to be lower than when the rollers were not cooled. This result suggested that the thermal contraction of the PTFE during cooling causes the PTFE in the concave area to peel off. From these results, it is assumed that the reason for the dispersed anchor effect is due to the influence of heat removal by the roller pressurization.
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