STRAIN CONTROL WELDING METHOD

PURPOSE:To perform butt welding of high quality by always restraining works by the proper pressing force. CONSTITUTION:When the works A and B are subjected to butt welding while being pressed and restrained upon the fixed supporting surface 3, the works A and B are pressed upon the fixed supporting surface 3 at the specified pressing force by pressure devices 6a and 6b via pressure sensors 7a and 7b at plural places of the position along a weld line close to the weld line 1. The positions in the pressing direction of the works A and B at this time are then detected by distance sensors 24a and 24b and made to the set positions and the pressing force by the pressure devices 6a and 6b is controlled so that position detected values 25a and 25b of the distance sensors 24a and 24b are made to the set positions for the variation of reaction force of the works A and B generated in accordance with welding.