GB431046A - Improvements in and relating to apparatus for grinding twist drills and like tools - Google Patents

Abstract

431,046. Grinding twist drills. PAIGE, W. R., Drill Square, Langsett Road, Sheffield. Dec. 30, 1933, No. 73. [Class 60] In a machine for grinding the ends of twist drills and the like, of the kind in which the work-holding chuck 51 is mounted on a spindle 48 which is adjustable longitudinally in an outer spindle 47 to accommodate drills of different length, the spindles being rotated, reciprocated axially by a cam, and mounted in bearings on a support 44 oscillated by a eccentric device about a pivot 43 in the vertical plane of the drill axis, there are provided two grinding wheels 34, 35 and two cam mechanisms for reciprocating the spindles, adapted for selective operation according to which wheel is in use. In the apparatus shown, a table 30 angularly adjustable on a slide 32 carries at.its inner end a pivot 43 on which is mounted the oscillatable support 44 carrying bearings 45, 46 in which the outer spindle 47 is slidably and rotatably mounted. The inner spindle carrying the chuck 51 is longitudinally adjustable in the outer spindle and is secured to it by a nut 49 threaded on the split end of the latter. The spindles are rotated by a hand-wheel 60 through gears 55, 56, 59, and the longitudinal reciprocation is imparted by spring-pressed plungers 68, 74, Fig. 4, mounted in the bearings, either of which can be caused to engage a corresponding cam groove 66, 76 in the spindle 47, whilst the other is retained in a withdrawn position. The support 44 is oscillated about the pivot 43 by means of an arm 63, Fig. 3, extending between a radially-adjustable eccentric pivot on a disc 62 mounted on the shaft of the pinion 56 and a pivot 64 adjustable in a slotted extension 65 of the table 30. The wheel 34 is for grinding the end faces of the drill, and the wheel 35, which is driven through chain and sprocket gearing from the shaft of the wheel 34, is for cutting relieving grooves near the point of the drill, as described in Specification 364,750, [Group XXII]. To distribute wear evenly over the face of the wheel 34, the wheel may be reciprocated axially, for example by means of a pin engaging a cam groove in its spindle. A vertically-adjustable rest 54 for the end of the drill is provided.