Patent GB-1052472-A (GB)
IPC: B23Q5/32
Abstract: 1,052,472. Machine tool details. A. P. L. THOMAS. June 7, 1963 [March 7, 1962], No. 8743/62. Headings B3C, B3K and B3N. [Also in Division F2] A drilling, tapping, or milling head comprises a casing 1, Fig. 3 (not shown), mountable on a machine by a flange 3 or a flange 4, an internally splined electric motor-driven sleeve 10, a spindle 17, rotatable with but slidable in the sleeve, and a rotatable nut 12 co-operating with a threaded portion 17a of the spindle to provide axial feed of the latter. Nut 12 is mounted in a housing 14 which is axially displaceable in the easing but is normally held against such displacement by a plunger 15. A chuck may be secured to a coupling 20, Fig. 1 (not shown), or the coupling may be replaced by a quill-box 21, Figs. 3, 5 (not shown), which comprises a quill 68, driven at a greater speed than spindle 17 by gears 69-72. A trip rod 24 carries an adjustable sleeve 25 comprising a dog 26, and a dog 27, and the dogs actuate limit switches at each end of the stroke, a safety switch 28 also being provided which is actuated by a roller 29. A sprocket 30 secured to sleeve 10 drives a sprocket 33 secured to the hub 34 of the armature 35 of a fast approach electromagnetic clutch 36, a gear-wheel 31 secured to sleeve 10 drives a gear 38 secured to the armature 45 of a feed clutch 46, through pick-off gears 39, 40, and a sprocket 32 secured to nut 12, drives a sprocket 48 secured to the armature 50 of an electromagnetic brake 51, the armature being fixed to shaft 37. When clutch 36 is energized lay shaft 37, and nut 12, are driven at a considerably greater speed than that of spindle 17, and the latter is fed at the fast approach speed. As the tool contacts the work, sleeve 25 actuates the change over switch to de-energize clutch 36 and energize feed clutch 46, layshaft 37, and nut 12, rotate at a less speed, and the spindle is fed at the feed rate. Collar 26 actuates a switch to de-energize clutch 46 and energize brake 51 to stop the rotation of nut 12 and retract the spindle. Dog 27 then actuates the limit switch to de-energize the brake, and spindle 17, and nut 12, rotate idly or clutch 36 may be energized to start another sequence of operations. Dogs 26, 27, may be adjusted by depressing an inching switch 54, and should the resistance to feed become excessive, nut 12, and housing 14, are moved axially to actuated switch 28, so that the particular clutch is deenergized, and the motor is stopped. The spindle may be driven by electric motor 7, Fig. 3 (not shown), or a power unit comprising a stator 56 and rotor 57, Fig. 5 (not shown), may be used. In a modification, Fig. 5 (not shown), fast approach clutch 36 is secured to a stub shaft 58, armature 45 of feed clutch 46 is driven by gears 61-65, the armature 50 of brake 51 is driven by sprockets 33, 48, and nut 12 is driven by sprockets 60, 32. In a further modification gear train 61-65 is replaced by split pulleys 74, 74a, and 75, 75a and a belt 76, Fig. 6 (not shown), the pulley halves 74a, 75a being adjustable axially to vary the drive ratio. Gears 31, 38-40, Fig. 3 (not shown), may also be replaced by split pulleys, and uni-directional motor 7 or 56, 57 may be replaced by a reversible motor, and the brake omitted when using the head for tapping.