Patent GB-1010409-A (GB)
Title: Improved lapping machine
IPC: B24B3/36
Filed: 1963-03-25
Abstract: 1,010,409. Sharpening tools; boring tools. A. W. WELLUM, and A. G. WELLUM. June 10, 1964 [March 25, 1963], No. 11737/63. Headings B3C and B3D. A portable lapping machine for use in sharpening jig boring and other tools tipped with tungsten carbide or high speed steel comprises a base, a lapping wheel mounted on the base for rotation about a horizontal axis, an electric motor for driving the lapping wheel, a feed shaft which extends parallel to the axis of the lapping wheel, a micrometer adjustment for moving the feed shaft endwise in relation to the base, a block which is axially adjustable on the feed shaft and capable of being locked to the feed shaft, a tilt bracket mounted on the block for adjustment about an axis transverse to the axis of the feed shaft, a scale for indicating the position of adjustment of the tilt bracket in relation to the shaft, means for locking the tilt bracket in adjusted position, a tool holder rotatably mounted on the tilt bracket and having a trunnion extending downwardly into a recess in the tilt bracket, another scale for indicating the position to which the tool holder has been adjusted about the trunnion in relation to the tilt bracket and means for locking the tool holder in adjusted position. A machine for sharpening a tool having a tungsten carbide tip 11, has a flanged base 12 supporting an electric motor 14 and a bracket 15 in which is journalled a shaft driven by the motor 14 and carrying a diamond-impregnated  lapping wheel 16. The bracket 15 carries a plate 18 on which is inscribed data relating to the geometry of the tool tip 11, a flexible support 54 for an electric lamp, and a trough 19 for collecting coolant. The base 12 constitutes a tray to collect any coolant spilling from the trough 19. Brackets 21, 22 on the base 12 support a feed shaft 20 adjustable endwise by a micrometer screw 24, backlash being taken up by a spring 25. A lug 28 on the feed shaft 20 carries a screw 29 coacting with the flange 13 of the base to limit the extent to which the feed shaft 20 can rock in the brackets 21, 22 towards the lapping wheel. A block 30 is slidable on the feed shaft 20, being locked in a desired position of adjustment by a screw 31, and supports a turret 32 for supporting the tool to be sharpened. A tool with a round shank is fitted into a hole 33 in the turret housing a V-groove 34 at its base and clamped by screws 35; if the tool shank is considerably smaller than the hole 33, a packing piece 36 is used. A tool with a rectangular shank is placed in the angle between faces 37, 38 of the turret and clamped by lugs 39 fitted with heel screws 40 and held in position by nuts 41. A scale plate 42, divided into four segments graduated from 0-90 degrees, is attached to the undersurface of the turret and rests on the top of a tilt bracket 44. A trunnion 45 screwed into the base of the turret is accommodated in a recess 46 in the tilt bracket. The turret is secured in any desired position of adjustment about the axis of the trunnion 45 by a clamp screw 47. The tilt bracket 44 is pivotally mounted on a pin 48 accommodated in a lug 49 on the block 30, the bracket being locked in any desired position of adjustment about the axis of the pin 48 by a screw clamp 5b. A scale 51 on the block 30 is visible through a window in a downward extension 53 of the tilt block. Operation.-The tool is mounted in the turret 32 with its shank parallel to the feed shaft 20 and the turret is adjusted about the axis of the trunnion 45 to the angle α, Fig. 2, as shown on scale 42, and clamped by screw 47. The tilt bracket 42 is adjusted about the pin 48 to the angle #, Fig. 1, as shown on scale 51 and clamped by screw 50. The block 30 is advanced along feed shaft 20 until the tool tip is close to the lapping wheel 16 and clamped by screw 31. Screw 24 is adjusted to bring the tool tip into contact with the lapping wheel and the tool wiped by hand across the lapping wheel by rocking the feed shaft 20 in the brackets 21, 22. The screw 24 is adjusted and the tool again wiped over the wheel, these operations being repeated until the face C has been satisfactorily lapped. Turret 32 is then rotated to position the tool with its shank at right angles to the feed shaft 20 and tilt bracket 42 adjusted about pin 48 to set the face A at the angle 0, Fig. 3, as shown on scale 51 and the face lapped until the point of the tool tip is in desired condition. The tilt bracket is then adjusted about pin 48 to the angle #, Fig. 3, as shown on scale 51, and the tool lapped to produce the secondary land B, the operation being terminated when the width of the land A has been reduced below 0À02 inch.