Welding gun apparatus

A welding gun apparatus for resistance welding, said welding gun apparatus comprising:

• fixed electrode means and movable electrode means for welding a workpiece at a welding station between said fixed electrode means and said movable electrode means,
• fixed electrode arm means provided with said fixed electrode means,
• fixed plate means to which said fixed electrode arm means is rigidly secured,
• driving cylinder means,
• piston means slidable within said driving cylinder means,
• piston rod means attached to said piston means and extending upwardly in a substantially vertical direction,
• movable electrode arm means provided with said movable electrode means,
• carriage means for holding said movable electrode arm means connected with an upper end portion of said piston rod means,
• piston rod movement regulating means for restricting the movement of said piston rod means in the substantially vertical direction, said piston rod movement regulating means including first engaging means provided on said piston rod means and first guide track means for guiding said first engaging means, said first guide track means being formed in said fixed plate means and extending in a substantially vertical direction, and
• cam means including second guide track means formed in said carriage means and second engaging means provided on said fixed plate means, said second guide track means being arcuate and including a vertical track portion at an upper portion and a sloped track portion at a lower portion, said second engaging means being engaged with said second guide track means, the height of said second engaging means being substantially the same as the height of the welding station, said first engaging means and said second engaging means being aligned with a longitudinal axis of said piston rod means, said cam means forcing said movable electrode arm means to move upwardly in the substantially vertical direction at a first stage and then upwardly and obliquely to locate said movable electrode means at a position apart from said fixed electrode means with a sufficient distance for feeding the workpiece into and from the welding station as said piston means is forced upwardly.