Abstract: An automatic welding apparatus comprises a welding torch including an electrode and a fixture for fixing a workpiece, and a relative positional relation of the welding torch and the workpiece fixture is controlled such that the electrode of the welding torch is moved to trace the welding line of the workpiece, whereby automatic welding is achieved. The automatic welding apparatus further comprises a switch for selectively connecting the electrode of the welding torch to a welding power supply or a detecting power supply, and a sensor for sensing a current or a voltage between the electrode and the workpiece when the electrode is switched to the detecting power supply, whereby the relative positional relation between the welding torch and the workpiece is detected in response to the output of the sensor, and thus a welding point or a welding line is sensed.

Abstract: An automatic welding apparatus comprising a workpiece fixture carried by a moving member for rotation about a horizontal axis extending in a back and forth direction, said moving member being provided on a carriage for sliding movement in a lateral direction, said carriage being provided for sliding movement in said back and forth direction, and a torch fixture carried by an arm for rotation about a vertical axis, said arm being provided for sliding movement in the vertical direction. In another embodiment, the workpiece fixture is provided only for rotation about a horizontal axis extending in the back and forth direction, and the torch fixture is carried by the arm for rotation about the vertical axis, which arm is provided at the end of a column for sliding movement in said lateral direction, which column is provided on a sliding member for sliding movement in the vertical direction, which sliding member is provided on a guide for sliding movement in said back and forth direction.