Patent ID: 7125209

Claim:
In an automatic screw machine having a stationary spindle mounted on a stationary head in axially-spaced relation to a rotatable spindle mounted on an indexable head, the improvement comprising: a quick-change mechanism operatively associated with said stationary spindle, said mechanism including a frusto-conical first surface on said stationary spindle; a tool holder adapted to hold a tool and having a frusto-conical second surface, said first and second surfaces being so configured and arranged as to urge said tool holder to move radially toward a concentric position with respect to a longitudinal axis of said stationary spindle when said tool holder is moved axially to engage said stationary spindle; and a multiple-lead threaded connection between said tool holder and said stationary spindle such that said tool holder may be quickly locked into mating engagement with said stationary spindle by relative rotation therebetween through a short angular distance of less than about one revolution of said tool holder relative to said stationary spindle.