GB1345736A - Screw feed unit heads - Google Patents

Abstract

1345736 Spindle feed; drilling heads; milling headstock; screwing headstock WAVIS ENG DEVELOPMENT CO Ltd 2 July 1971 31011/71 Headings B3B B3C B3K and B3N An automatic screw feed unit head, e.g. a plurality of which may form a machining centre around a work-table, in which a drive motor 27 rotatably drives a spindle 24 and the said spindle is fed axially by a screw and nut 30, 33 relative to a base member 20, is characterized in that a first element of the screw and nut feed, e.g. the nut 33, is rotatable and axially translatable relative to the base member but is non- translatable relative to the spindle, a second element, e.g. the feed screw 30, is fixed against both rotation and displacement relative to the base member, and wherein drive means is provided for transmitting rotary drive from the spindle through clutch means to the first element to translate the latter and the spindle relative to the base member at a feed speed, and a quick traverse motor is provided for rotating the first element in either direction to translate the spindle more rapidly, the clutch means then permitting rotation of the first element independently of the spindle. The spindle 24 is adapted to carry a drilling, milling or boring tool or a multi-spindle head. The drive means may be in the form of a removable drive unit 35 bolted to a sliding body 23 that carries the spindle 24. The drive unit 35 has a first input 37 from the spindle drive, a second input from the quick traverse motor, and a single output 36 connected to the rotary nut 33 via worm gear 53 and a sleeve 31. The drive unit 35 also includes the clutch means which may be electromagnetic or hydraulic, and a pair of gears (40), (41) (Fig. 4, not shown) which may be changed to alter a gear ratio without removing the drive unit from the body 23. In an alternative embodiment the feed screw is rotatably mounted in a thrust block 29 on the base member and the nut is rotationally and axially fixed to the body 23, the drive unit 35 being mounted in the thrust block 29, the feed screw then being driven either from the spindle drive for a feed motion or from a rapid traverse motor in the drive unit 35. Alternatively a separate, e.g. a third motor may be provided for the feed motion. The clutch has a torque override so that when the body 23 abuts a stop the clutch slips, e.g. to allow dwell at the finish of a drilling operation. Fig. 1 (not shown) shows a prior art unit head in which a spindle 9 is driven rotatably by motor 11 and also axially by the same motor via gearing to a rotatable nut 16 engaging a feed screw 4. For fast traverse a separate motor 6 rotates the feed screw 4, and an electromagnetic brake 8 is used to hold the feed screw rotationally fixed during a slow feed of the spindle.