Machine tool having dual spindles and tool rests

A machine tool, said machine tool having a frame and first and second spindle stocks on said frame disposed so as to face each other with a space provided in said frame therebetween, said first and second spindle stocks having first and second workpiece spindles rotatably supported thereby, respectively, each said workpiece spindle having a chuck for jointly holding therebetween, or independently and separately holding, a workpiece to be machined, and said machine tool further comprising:

• said first and second spindle stocks on said frame being capable of moving at least one of said spindle stocks relative to the other only in the direction of the central axis of said first and second workpiece spindles and over said space to enable transfer of a workpiece from one of said first and second spindle stocks to the other said spindle stock;
• first and second tool rests disposed on said frame on the same side of said central axis corresponding to and adjacent to said first and second workpiece spindles, respectively, each said tool rest having means for moving said tool rest in at least a direction substantially perpendicular to said central axis of said first and second workpiece spindles and each of said tool rests having a side thereof oriented substantially perpendicularly to said central axis and facing the other said tool rest;
• first and second rotatable tool holding turrets disposed on said first and second tool rests, respectively, free to be rotated on an axis parallel to said direction of said central axis of said first and second workpiece spindles, said first rotatable tool holding turret disposed on said side of said first tool rest facing said second workpiece spindle and said second rotatable tool holding turret disposed on said side of said second tool rest facing said first workpiece spindle, said first and second turrets being disposed over said space;
• said first turret having a peripheral portion with a plurality of tool installation portions formed thereon such that when one of said plurality of tool installation portions is selectively positioned at a position for machining a workpiece, said positioned tool installation portion protrudes toward said central axis of said workpiece spindle beyond a front portion on the workpiece spindle central axis side of said first tool rest having said first turret installed thereon;
• said second turret having a peripheral portion with a plurality of tool installation portions formed thereon such that when one of said plurality of tool installation portions is selectively positioned at a position for machining a workpiece, said positioned tool installation portion protrudes toward said central axis of said workpiece spindle beyond a front portion on the workpiece spindle central axis side of said second tool rest having said second turret installed thereon;
• a plurality of tools on said tool installation portions of said first tool holding turret, said tools each having a workpiece machining portion, and each said workpiece machining portion of said plurality of tools positioned on said tools and said tools positioned on said first tool holding turret such that said workpiece machining portions are directed toward said first workpiece spindle such that said tools are selectively positionable by said first tool holding turret to machine a workpiece on said first workpiece spindle;
• and
• a plurality of tools on said tool installation portions of said second tool holding turret, said tools each having a workpiece machining portion, and each said workpiece machining portion of said plurality of tools positioned on said tools and said tools positioned on said second tool holding turret such that said workpiece machining portions are directed toward said second workpiece spindle such that said tools are selectively positionable by said second tool holding turret to machine a workpiece on said second workpiece spindle;
• wherein at least one tool among said tools installed on said first and second tool holding turrets is an inside diameter machining tool.