Abstract: There is disclosed a method for the plasma arc welding of corrugate membranes, which can prevent a welding failure from occurring around the corrugate portion. In this welding method, NC data for robot control are modified so as to gradually change a torch angle around the R portions at a rate not greater than the maximum angular velocity and increase a welding speed around the R portions of foot regions of corrugate portions 1B and 2B and the R portion of an apex 22 before a welding torch 12 reaches the R portions. Three parameters are prepared for determining the deformation of the corrugate portions 1B and 2B in terms of height, width of the foot regions and the swell of the trunk portion. Data indicative of the height and foot width of the corrugate portion measured by a laser displacement sensor 15 are compared with standard corrugation NC data, and the NC data for robot control are modified to correct the height, foot width and swell degree thereof by utilizing the parameters.

Abstract: An automatic welding apparatus including a robot which comprises a base, a rotary support rotatably mounted on the base, a pair of first arms pivotally movable together and rotatably supported each at its one end by the rotary support, a second arm rotatably supported by the other ends of the first arms at an intermediate portion close to its one end, and a hand connected to the other end of the second arm and rotatable about two axes intersecting each other at right angles. A core wire is supplied from a feeder to a welding torch attached to the hand of the robot. A control device controls movement of the robot, operation of the core wire feeder and power supply to the welding torch. When the forward end of the welding torch comes into contact with the work to be welded, with the core wire drawn into the torch, the resulting short-circuiting is detected to detect the position of the work.