Feed drive arrangement for machine tool table etc. - has leadscrew supported in rotatable nuts of crossbeams which are driven along bed guideways at half table speed by auxiliary leadscrew and which raise critical speed of leadscrew

摘要

The table (10) has linear ball bearing units (8) running on guideways (6), and is driven along the bed by a leadscrew (2) supported in end bearings and engaging with a recirculating ball nut (3) fixed to the table. Also running on the guideways (6) are two crossbeams (13,14) connected by a bar (15) and having rotatably mounted recirculating ball nuts (4,5) in engagement with the leadscrew (2). Driven at half speed by a timing belt from the leadscrew (2) is an auxiliary leadscrew (16) of the same pitch and in engagement with a nut (24) fixed to the crossbeam (13) nearest the feed drive motor (23). Since the crossbeam nuts (4,5) are rotatably mounted the position of the beams along the bed is determined only by the rotation of the auxiliary leadscrew. Corresponding to the movement of the table (10) the crossbeams move at half speed to maintain optimum support of the leadscrew. USE/ADVANTAGE - Feed drive arrangement for machine tool table etc. raises critical speed of leadscrew and minimises vibration, esp. in high speed drives. System alignment is easily maintained.