Patent GB-537633-A (GB)
Title: Cylindrical grinding and lapping machine
IPC: B24B35/00
Filed: 1940-02-28
Abstract: 537,633. Grinding and lapping machines. NORTON, CO. Feb. 28, 1940, No. 3674. Convention date, March 9, 1939. [Class 60] A grinding machine having a grinding wheel for grinding cylindrical surfaces is also provided with a lapping device having one or more abrasive sticks which are reciprocated in contact with the rotating work while the latter remains in its grinding position. In the application to a machine of the kind described in Specification 463,334, the work may be mounted between centres and reciprocated past the wheel 15. Alternatively, a short work-piece may be ground by a plunge-cut operation. The grinding wheel is driven by a motor 16 and fed as described in Specification 498,295. A lapping head 18 is mounted on the wheel slide 12. Abrasive sticks 20, which may be crystalline alumina, or silicon carbide with a suitable bond, are mounted in a block 21 pivoted at 24 to arms 22 secured to a frame 23 pivoted to slidable blocks 29 so that the frame may have both a rocking and a vertical reciprocating movement. During the rocking movement which is effected by a hydraulic cylinder 45 a roller 49 on the frame rolls on a cam 48 so that the lapping sticks move rectilinearly over the work. The entire lapping head is adjustable vertically to and from the work on guides 58 by means of a hydraulic cylinder 100 and is also adjustable laterally by rack and pinion gearing 72. The lapping-head may also be adjusted longitudinally of the work by means of a slotted plate 59. To compensate for wheel wear micrometer mechanism 75 is connected to a feed screw 76 operating as described in Specification 498,295 and the wheel slide is fed by hydraulic cylinders 80, 83. Preferably the lapping head and the grinding wheel are automatically and alternatively moved into co-operation with the work. When the grinding-wheel moves forward the lapping head moves with it until a chain 86 becomes tensioned after which the grinding wheel slide is moved the required further distance up to the work. Any adjustment of the wheel by the mechanism 75 will cause a friction gib 90 between the slide 12 and the lapping slide 64 to stop, the chain 86 holding the lapping slide stationary. When the wheel housing is moved back by the piston 81 all the parts are returned and the lap is correctly positioned over the work. The hydraulic circuit is shown in Fig. 10. A pump 105 delivers oil to a valve 110 controlled by a hand lever 115. In the position shown, oil passes to a line 116 to withdraw the piston 81. At a pre-determined point, pressure fluid passes to a line 118 to the lap controlling valve 120, which is controlled by a lever 124. As shown, pressure fluid flows through line 125 to the cylinder 100 to lower the lapping head. To return the lapping head the valve 120 is changed over. A cone 136 on the valve spindle 121 co-acts with a sliding member 137 and a stop collar 140 so that the lever 115 cannot be operated to move the wheel slide up to the work until the lapping head has been withdrawn. A nut 142 may also be adjusted to prevent piston 81 moving to the left, Fig. 10, sufficiently to uncover the pipe 118 which prevents the lap from being brought down to the work while the wheel is in operation. The lapping sticks are reciprocated as described in Specification 535,227, [Group XXIX]. A pilot valve 157 moves within a hollow reversing valve 155 to control admission to a cylinder 45 which reciprocates a disc 42. The latter co-operates with collars 164, 165 to shift the reversing valve at the ends of the stroke. When the valve lever 124 is moved to the left the reciprocations of the lapping arm are stopped. In a modification, the lapping sticks may be universally mounted. For this purpose the sticks may be carried on a block 201, Fig. 14, pivoted at 204 to another block 205 which is itself mounted on cross pivots 206 on the side bars 207 of the lapping frame. Specifications 471,287 and 537,632 also are referred to.