The quality of welded pipe depends on the quality of welding. The quality of welding is not only directly related to the quality of the tube, especially with the design of the forming roll, the forming process, the choice of welding parameters. These factors with the equipment to adjust the state and the rapidly changing, only by visual inspection of welding sparks, shavings and simple flaring state, flattening test and other empirical methods of control, it is difficult to maintain a stable quality.

The shape and width of the weld affected zone are closely related to the welding speed, temperature, extrusion force and even tube thickness. When the welding speed constant, the heat affected zone width and welding temperature is proportional to (ie, the higher the temperature, the width of the larger), and inversely proportional to the extrusion force (ie, the greater the extrusion pressure, the smaller the width); when squeeze (Ie, the higher the temperature, the greater the width), and inversely proportional to the welding speed (that is, the faster the faster the width of the smaller); when the welding temperature does not change, the heat-affected zone width is proportional to the welding temperature, The width of the heat-affected zone is inversely proportional to the extrusion force (ie, the larger the squeezing force and the smaller the width), and is inversely proportional to the welding speed (ie, the faster the width and the smaller the width). Thus, the welding process should be welded within the scope of safety, fully explore the potential of pipe equipment, according to the wall thickness of the tube, the rational allocation of induction coil position and the size of the opening angle to ensure adequate heat output conditions, and gradually increase the welding Speed, the appropriate extrusion force to make the formation of the ideal heat affected zone shape, and in this state stable operation, the welding quality will be able to steadily improve.