Numerically-controlled lathe, numerically-controlled device therefor and processing procedure thereby

A numerically-controlled lathe, comprising:

• a bed (1);
• a first headstock (2) fixed to said bed;
• a first spindle (22) freely and rotatably supported in said first headstock (2);
• a first spindle motor (4) for rotatably driving said first spindle (22);
• a second headstock (5) arranged on said bed (1) to face said first headstock (2) and being drivably controlled in same direction with axis of said first spindle (22);
• a first servo-motor (6) for driving said second headstock (5) in at least said same direction;
• a second spindle (23) with same axis of said first spindle (22) freely and rotatably supported in said second headstock (5);
• a second spindle motor (9) for rotatably driving said second spindle (23);
• a first tool rest (11) which is drivably controlled in at least two perpendicularly intersecting directions, said first tool rest for processing a workpiece mounted on said first spindle (22)
• second and third sever-motors (10, 17) for driving said first tool rest (11) in at least said two perpendicularly intersecting directions;
• a second tool rest (2) drivably controlled in at least a single direction for processing the workpiece mounted on said second spindle (23);
• a fourth servo-motor for driving said second tool rest in at least said single direction;
• a third tool rest (30) drivably controlled in at least two perpendicularly intersecting directions for processing the workpiece simultaneously in association with said first tool rest (11) or said second tool rest (2) to aid processing of the workpiece on said first spindle (22) or said second spindle (23) during its processing operation of the workpiece;
• a fifth and a sixth servo-motors (33, 37) for driving said third tool rest (3) in at least said two perpendicularly intersecting directions;
• a first program memory means (100) for storing a processing program used to process said workpiece mounted on said first spindle (22) by means of said first tool rest (11);
• a second program memory means (100) for storing a processing program used to process said workpiece mounted on said second spindle (23) by means of said second tool rest (20);
• processing time-computing means (81, 90) for computing the time needed for said first tool rest (11) and said second tool rest (2) to process the workpiece;
• step shifting means (91) for comparing the time needed for said first tool rest (11) and that needed for said second tool rest (2) to process the workpiece respectively, and then allocating the steps so that the processing time may be able to equal between them;
• program memory regions (92, 93), (93) to equal the time needed for said first spindle (22) and said second spindle (23) to process the workpiece, by causing the third tool rest (3) to take up a certain processing operation for the workpiece otherwise to be carried out by said first spindle (22) or said second spindle (23), when the comparative results and the allocation of the process time are not equal between said first spindle and said second spindle.