Abstract: A method of locating and welding a seam with a welding torch includes the steps of swinging the welding torch transversely of its feed direction, moving the torch at an angle of up to 30.degree. with respect to a preprogrammed torch path, operating the torch at a low welding current, and comparing welding current or voltage values measured at the laterally outermost points of the torch movement until such values are substantially equal, indicating the torch is centered over the seam. Thereafter, the torch is moved rearwardly along the seam until the measured voltage or current values indicate an end of the seam has been reached, and the torch is then supplied with full welding current and is moved forwardly along the seam at relatively high speed according to the preprogrammed path in order to weld the seam.

Abstract: A welding robot having an elongated arm pivotally mounted on an upright turret which is movable about the upright axis thereof. As a result, the arm is swingable about the aforesaid upright axis. A fine movement control device or commuter is mounted on an end of the air remote from the aforesaid pivotal attachment thereof to the upright turret. The fine movement control device has a welding gun mounted thereon with structure being provided in the control device for permitting the welding gun to move through a very fine pattern of movement independent of the movement of the arm. A preprogram is provided for moving the arm in a predesignated direction to coincide with the path of a welding seam. Variations of the welding seam from the preprogram can be controlled by the structure in the fine movement control device so that the welding torch will follow the actual welding seam even if it varies from the preprogrammed path thereof.

Abstract: A planet guide roller welding wire feeding arrangement having at least two planet guide rollers rotatably mounted on a bearing part with the axes of rotation thereof defining an angle with the welding wire axis and are arranged radially outwardly from the welding wire axis. The bearing part encircles the welding wire and is supported for rotation with respect to the welding wire. The bearing part consists of a cylindrical sleeve having a slotted wall structure so that at least two parts thereof are movable toward and away from each other. The guide rollers are rotatably mounted on these two movable parts so that the guide rollers can be adjustably moved toward and away from each other. Structure is provided for facilitating the adjusting of the guide rollers toward and away from each other, which structure is responsive to a relative axial movement between a gripping member encircling the bearing part and selectively fixedly secured thereto.

Abstract: Guide tube for an arc welding gun. The normal threaded connection between the guide tube in an arc welding gun and the holder for same has been improved for the purposes of electrical transmission by utilizing tapered threading for same. Particularly it has been found that the electrical conductivity through said parts is substantially improved if such conical threading is of such design that the conicity of the thread is at a ratio of 1:16 .+-. 20 percent.