GB890035A - Improvements relating to machines for grinding points on drills - Google Patents

Abstract

890,035. Grinding drills. BODDAERT, W. R. Nov. 25, 1960 [Dec. 31, 1959], No. 44357/59. Class 60. A machine for grinding the point of a drill 3 comprises a centring vice 6 and a chuck 4 which are adapted to grip the lands of the drill and are mounted on a block 7 pivotal about an axis X disposed in the plane Z of the face of a grinding wheel 2, means 12A for rotating the chuck about the axis of the drill, means 15 for adjusting the position of the chuck longitudinally of the axis of the drill, a member 22 by which the position of the drill can be set in the chuck, and means 31 for dressing the face of the grinding wheel. The pivot block 7 is rotatably mounted in a member 8 on the end of a shaft 9 which is axially adjustable by a hand-wheel 1C to position the axis X of the block in the plane Z of the face of the grinding wheel. The block has a guide-way 17A for a block 17 which supports the chuck 4 in a gimbal 16A for movement about a pin 16 whereby the drill point can be supported on a rest 5 during a grinding operation or be presented to the setting device 22 which is adjustable by a screw 25; movement of the block 17 along the guide-way 17A determines the angle of the point of the drill. After positioning the point of the drill against the setting device, the drill is gripped in the chuck 4 by rotation of a nut 29 which presses jaws 26 against the lands of the drill. The drill is then moved on to the rest 5 and centred by jaws 6 movable by a screw 18 connected to the jaws by a slide 20, push rods 19 and levers, the jaws gripping the lands of the drill. Thereafter, the block 7 is rocked to move the point of the drill across the face of the grinding wheel. The drill is ground with two pairs of corresponding facets set at the backing-off and cutting angles, the backing-off angle being determined by a stop 7B in a recess 8A and the cutting angle being determined by an adjustable nut 11. The chuck 4 can be axially adjusted by rotation of a nut 15 and rotated through 180 degrees to a position determined by interengaging lugs by axially moving and then rotating a nut 12A. The pivot block 7 can be moved to a position wherein a diamond 31 carried therein can be traversed across the face of the grinding wheel, rotation of the handwheel 10 feeding the diamond and the pivot block towards the grinding wheel to maintain the axis X in the plane Z of the face of the grinding wheel. An inspection lamp 23 and a light 32 are provided to assist in adjusting the position of the drill. The machine can be adjusted to grind right and left-hand drills and assembly of the shaft 9 and handwheel 10 can be modified to receive a webthinning attachment.