Patent GB-772246-A (GB)
Title: Improvements in and relating to lapping machines
IPC: B24B3/34
Filed: 1953-06-04
Abstract: 772,246. Lapping. FENLIND ENGINEERING CO. June 4, 1953 [Nov. 3, 1952; Feb. 6, 1953], No. 15488/53. Class 60 A workpiece, such as a carbide tipped tool bit, is lapped by an endless abrasive belt 19 where it passes around a wheel 20. The belt 19 also passes around a drive pulley 14 on the shaft of an electric motor 13, the belt being tensioned by pivotally mounting the motor at 30 on a base plate 12 whereby the weight of the motor swings it about a horizontal axis; a cam 32 co-operating with the motor base 31 can be operated by a handle 34 to relieve the tension. The base plate 12 is supported on the machine table 10 for adjustment about a pivot pin 17, the vertical pivoted axis passing through the axis of the motor shaft at the middle of the pulley 14, adjustment, for correct tracking of the belt, is effected by a hand wheel 23 on a rod 21 which is threaded to engage a nut 25 slidable in a bearing 26 fixed to the table, the nut having a pin 27 engaging a slot 28 in a lug 29 projecting from the plate 12. A shaft 70 operated by lever 72 carries an eccentric 69 adapted to engage frictionally the interior of the rim of the wheel 20 so as to stop it quickly, The workpiece 35 is mounted on a support 36 and may be positioned at a desired angle by examination against a protractor slidable back and forth in a groove 36<SP>1</SP> extending crosswise of the slide parallel to the working face of the abrasive belt 19. The support 36 is adjustable by a screw 39 toward and away from the wheel 20 on a table 37 carried on a pillar 38 vertically adjustable to determine the angle of the surface lapped on the workpiece. The pillar 38 slides in a vertical guide bearing 48 and has a key way 49 receiving the inner end of a clamping screw 50. A vertical adjusting screw 52 mounted in bearing 53 for rotation by hand wheel 54 engages a threaded hole in the lower end of the pillar. The wheel 54 has a scale 0-125 co-operating with an index mark M and pitch of screw 52 in such that one revolution of the wheel gives a vertical adjustment of 1/8 inch; the pillar has graduations in eighths of an inch. The micrometer adjustment is made in accordance with a table giving the necessary height of the support 36 for the desired angle having regard to the height of the workpiece. Alternatively, when extreme accuracy is not required, setting up is effected by using a direct reading gauge 60, the flat front face 61 of which has vertically spaced graduations 1/8 inch apart; the numerals indicate angles and the support 36 is vertically adjusted until the tip of the tool bit 35 registers with the desired graduation. The gauge 60 is on the other end of an arm 63 pivoted on a vertical pin 64 on a projection 66 on the front of the wheel support 67, a washer 68 being located between the arm 63 and top face of projection 66; the gauge 60 can thus be swung into and out of operative position. A sheet metal dust and safety guard 44 is provided. Dust discharged downwardly from the front of the wheel is conducted through passage 45 into pan 46 removably suspended on the front of the machine.