Spot welding machine for heavy-duty operations on surface contoured

Abstract

A spot welding machine comprising a pair of vertically spaced-apart guide rails rigidly supported on a framed structure a distance from the ground, a slide member slidably mounted on the guide rails, and a robot arm structure having a housing pivoted at an upper pivot point of the slide member, and outer and inner shafts axially movable as a single piece along the longitudinal axis of the housing, the inner shaft being rotatable about the longitudinal housing about which the inner shaft is rotatable. An electrode holder is attached to the forward end of the housing for unitary axial movement with the outer and inner shafts and for unitary rotation with the inner shaft to vertically swing an electrode tip attached thereto. A fluid operated telescopic cylinder is pivotally connected between the lower pivot of the slide member and a forward end portion of the housing for pivoting the robot arm structure at a desired angular position. A backing electrode is provided on the ground to mount a workpiece to which the electrode tip is addressed in response to a set of instruction data to make pressure contact therewith.