China
Africa
Explore chapters and articles related to this topic
Beneficial Industrial Uses of Electricity: Materials Fabrication
Published in Clark W. Gellings, 2 Emissions with Electricity, 2020
Upset welding is a resistance welding process that produces coalescence simultaneously over the entire area of abutting surfaces or progressively along a joint by the heat obtained from resistance to electric current. Pressure is applied before heating is started and is maintained throughout. The parts are clamped in the welding machine and force is applied bringing them tightly together. High-amperage current is then passed through the joint. When they have been heated to a suitable forging temperature, an upsetting force is applied and the current is stopped. The high temperature of the work at the abutting surfaces with the high pressure causes coalescence to take place. After cooling, the force is released and the weld is completed.
Development of an optimal scheme for controlling the ultrasonic welding process of artificial leather
Published in Welding International, 2019
S. S. Volkov, V. M. Nerovny, G. A. Bigus
Fixed upset welding is defined by the polymer upset δ, i.e. the depth of indentation of the waveguide into the workpiece being welded as a result of the effect of static welding pressure of ultrasonic vibrations. In the simplest case (Figure 1(a)), the ultrasonic vibrations are turned off by an opening contact and a push pin, mounted on the movable and stationary part of the welding machine. The distance between the contact and the pin corresponds to the specified settlement, the value of which is determined when working out the welding modes. The static welding pressure is valid until the end of the welding cycle [4]. When welding products made of plasticized polyvinyl chloride, artificial leather with a thickness of 0.7 to 1.6 mm, uncontrolled deformation of the welding zone after turning off ultrasound can lead to a significant deterioration in the appearance and strength characteristics of the joint. In order to prevent such deformation, it is advisable to limit the movement of the welding unit after turning off the ultrasound by installing a special lock or removing the static welding pressure Pst without lifting the welding unit.