Automatic tool changer

A workpiece handling apparatus for transferring workpieces along a transfer path extending from a first work station to a second work station wherein said work stations may be selectively set up to perform work operations on workpieces of a first configuration or on workpieces of a second configuration, said workpiece handling apparatus comprising:

• a transfer unit having a carrier member moveable along a plurality of selected paths, one of said selected paths corresponding to at least a portion of said transfer path;
• a first workpiece gripping unit adapted to releasably grip and support a workpiece of said first configuration;
• a second workpiece gripping unit adapted to releasably grip and support a workpiece of said second configuration;
• a first and a second holding unit respectfully mounted at locations spaced from said transfer path, each of said holding units including locating means for releasably supporting either of said first and second gripping units;
• first coupling means on said carrier member and second coupling means on each of said first and second gripping units cooperable to releasably couple said carrier member to one of said first and second gripping units in response to movement of said carrier member relative to said one of said gripping units;
• locking means on said carrier member moveable between a locked position and an unlocked position, said locking means being operable in said unlocked position to accommodate relative movement between said carrier member and said one of said gripping units for releasably coupling said carrier member to one of said first and second gripping units and operable in said locked position to releasably lock said carrier member in said one of said gripping units coupled to each other;
• lock actuator means operable when said carrier member is coupled with one of said first and second gripping units supported on said first and second holding units, respectively, for selectively actuating said locking means to its locked and unlocked position;
• and
• each of said gripping units having an elongate central frame member having said second coupling means located at one end of said central frame member and a pair of longitudinally spaced vertical bores extending upwardly from the bottom of said central frame member, said locating means having support means for supporting said central frame member in a substantially horizontal position, and a pair of spaced locating pins fixedly secured to and projecting vertically upwardly from said support means and adapted to be received in said vertical bores in said central frame member to retain said central frame member supported on support means against horizontal displacement relative to said support means.