Improvements in or relating to Spiral Drill Grinding Machine

1,167,218. Grinding drills. W. SCHANBACHER. 2 Aug., 1967 [5 Aug., 1966], No. 35407/67. Heading B3D. A twist drill grinding machine comprises a non-rotatable clamp 1 for a drill 12, grinding disc 15, and a swivel mounting controlled by a fixed template 38 for producing relative swinging movement between the drill and disc, the swivel mounting including first and second axes 5, 10 at right angles to one another and intersecting at a point 11 in the proximity of the grinding surface of the disc, the axis of a drill in the clamp passing through the point, the swivel movement controlled by the template also providing a relative longitudinal movement between the drill tip and grinding surface. As described, the grinding disc is driven by an electric motor 14 having a sleeve 19 axially and rotatably slidable by means of balls on an axle 18 secured to a bearing 16 on a hood 17, a spring urging the sleeve towards the bearing to a position determined by an adjustable rod 28 engaging through a ball 27 a curved portion 26 of an axially displaceable rod 25. The hood 17 is mounted for pivotal movement about the axis 10 on a curved part 6 which, in turn, is mounted for pivotal movement about the axis 5 on a base 3, the axes intersecting at the point 11 on the axis of the drill 12 which is carried on an adjustable clamp 42 on the base. The drill can be rotationally positioned on the clamp by a stop device 46, the clamp then being secured with the drill axis passing through point 11 by a toggle 47. A rod 40 extends from the grinding unit and acts as a follower engaging the template 38 which is secured to the base 3. Movement of the grinding unit by a handle 37 and controlled by the rod 40 engaging the template controls the grinding of the top of the drill, a link connection 34, 35 between the curved part 6 or base 3 and the axially movable rod 25 causing, during the movement of the grinding unit movement of the sleeve 19 along the rod 18 to effect the relative longitudinal movement between the drill and grinding surface. The drill is turned through 180 degrees for grinding its other edge or the machine is provided with opposed templates, one for each edge. In other embodiments, the curved surface of the grinding wheel is used, or the grinding surface is stationary and the movements are imparted to the drill.