Planetary wire-feeding mechanism for electric arc-welding applications

In an apparatus for converting the rotational force of a motor shaft to a prescribed linear force along a first axis for selectively advancing an elongated wire along the first axis, a substantially cylindrical hollow feed housing coaxial with the first axis and through which the wire may be advanced in a forward direction along the first axis, the housing having a radial flange intermediate its ends and a rear portion projecting axially rearwardly from the flange, the outer surface of the rear housing portion being threaded at a rear end thereof, first and second pistons supported in a forward portion of the housing on generally opposite sides of the first axis for radial reciprocation toward and away from the first axis, first and second rollers rotatably carried by the respective first and second pistons for planetary rotation about the first axis during a rotation of the housing, the first and second rollers respectively having axes that are skewed with respect to the first axis to cooperate when in an innermost radial position to engage the wire and to advance the wire along the first axis when the first and second rollers are rotated, a conical guide member supported for slidable axial movement on the outer surface of the rear housing portion, an adjustment nut disposed in threaded engagement with the rear end of the rear housing portion, a calibrated spring extending between the flange and the front end of the conical guide member to normally urge such member toward the adjustment nut, first and second levers individually pivoted in the housing intermediate their respective ends on generally opposite sides of the first axis, the first and second levers extending longitudinally in the housing, corresponding first ends of the levers terminating opposite the conical guide member and corresponding second ends of the lever terminating opposite the radially outer ends of the respective first and second pistons, resilient means coupled to each piston for urging the outer end of the piston against the opposed second end of the associated lever, means disposed at the first end of each lever for coupling such first end to the opposed portion of the conical guide member, and means for fixedly connecting the motor shaft to the rear housing portion.