Patent GB-578460-A (GB)
Title: Lapping or abrading machine
IPC: B24B47/06
Filed: 1944-05-16
Abstract: 578,460. Lapping-machines. NORTON CO. May 16, 1944, No. 9371. Convention date, Sept. 1, 1943. [Class 60] A lapping machine, for treating gauges &c., comprises a work support movable by fluid pressure means to apply the work-piece to the flat face of a rotating lap, which also has a gyratory movement, with a predetermined pressure ; a stop device for limiting the movement of the work-piece so as to size the work also is provided. The machine comprises a base 10, Fig. 1, supporting a vertically movable wheel slide 11 carrying, on a horizontal spindle 14, a lapping-wheel 17; the slide is adjustable vertically by a screw 18 carried by the slide and engaging a nut 19 on the base, the screw being rotatable, through gearing 21, 22, Fig. 3, by a hand-wheel 24. The work-piece 36, Fig. 2, shown as a caliper gauge, is clamped to the upper surface of a table 33 carried on ways 34, 35 on a transversely movable carriage 28, the table 33 being movable to apply the work-piece to the lap. The table 33 is moved by fluid pressure mechanism comprising a cylinder 40, Fig. 4, secured to the carriage 28, in which is movable a piston 43 connected by a rod 44 to the table, fluid being supplied, through pipes 80, 83, by a pump 55 from a reservoir 53 through a reversing valve 57, having thereon pistons 66-70; fluid enters through a pipe 56, and exhausts through a speed control valve 100, and pipe 107. The valve 100 has a stem 101 provided with pistons 102-104, the piston 103 having therein a V-notch 105 which registers more or less with a pipe 106 according to its circumferential position, as determined by rotation of the stem 101. which is located in its adjusted position by the engagement of a spring pressed pawl 114 with a notched part 113 of the stem 101 ; the stem thus may be moved longitudinally by a knob 110 to start or stop the table 33 without disturbance of its rotational adjustment. When the valve is in the full-line position shown, the notch 105 is out of line with the pipe 106 and flow of fluid is stopped, and in order to facilitate manual movement of the table 33 a pipe 122 is provided, connecting, through the valve 100, the pipes 80, 83; pressure from the valve 57 also is relieved by a pipe 121, so that the valve may be movable readily. The table 33 is movable manually by a handwheel 126, gear 128 and rack 129 secured to the table, and the carriage 28 is movable manually by a hand-wheel 134 on a feed screw 130 engaging a nut 133 mounted on the base 10. The valve 57 is movable manually by a lever 141 and linkage 143-149. In order that the workpiece 36 may be moved into engagement with the lapping-wheel 17 with a predetermined ,pressure; a valve 150 is provided, actuated, through an arm 156, by adjustable dogs 158, 159 on the table 33. The valve is held normally in the central position by a spring 160 and has pipes 161, 162 connected respectively to pipes 80 and 83, and pipes 163, 164 provided with adjustable throttle valves 165, 166 ; an adjustable throttle valve 168 also is connected between the pipe 107 and exhaust pipe 167. As the table 33 moves to carry one of the faces 36a, 36b of the work-piece up to the wheel 17; the appropriate dog 158, 159, just before the work engages the wheel, moves the valve 150, thus throttling exhaust from the cylinder 40 and diverting fluid from the pipe 80 or 83 through the throttle valve 165 or 166, thus reducing the operating pressure to that desired. Movement of the table, in order that the gauge may be lapped to the predetermined size, is limited by a stop-mechanism, comprising two dogs 170, 171 mounted adjustably on the carriage 28 and having micrometer screws 173, 174 to engage a lug 175 adjustably mounted on the carriage 33. In order to give a visual indication of the pressure between the work and the lap, two dial pressure indicators 176, 177 are provided, having plungers 178, 179 for engagement by the lug 175. The lap spindle 14 is mounted in ball bearings 15, 16 eccentrically carried by a sleeve 180 rotatable in the slide 11 ; the sleeve 180 carries a pulley 183 driven by a belt 184 from a motor 186 adjustable on the slide 11 to tension the belt. The spindle 14 carries a pulley 190 connected by,a belt 191 to a pulley 192 on a motor 193 supported on a platen 194 pivoted on a rock shaft 195 supported in the slide 11 ; a second platen 196 has one end pivoted on the shaft 195 and is rocked in synchronism with the revolution of the sleeve 180 by a strap 197 pivoted at 198 to the platen 196 and rotatably supported on an eccentric surface 199 on the hub of pulley 183. The platens 194, 196 are connected by a screw 200 engaging nuts 203, 204, adjustment of which serves to adjust the tension of the belt 191. In operation, the valve 110 is moved to start movement of the table 33, which carries the work-piece under the predetermined pressure against the lapping wheel until stopped by the stop lug 175, &c., the control lever 141 then is moved to shift the valve 57 so that the table 33 moves in the reverse direction to carry the other face of the work-piece against.the lapping- wheel until the stop lug &c..again terminates the lapping operation.