Patent GB-822370-A (GB)
Title: Improvements relating to the diamond dressing of grinding wheels
IPC: B24B53/00
Filed: 1956-12-11
Abstract: 822,370. Truing grinding wheels. JONES & SHIPMAN Ltd., A. A., and HOULDSWORTH, J. Dec. 11, 1957 [Dec. 11, 1956], No. 37800/56. Class 60. A grinding wheel dressing equipment for a cylindrical grinding machine comprises an abutment member 16, Fig. 1, which is adjustable to move a stop-face 17 thereon in and out of a pre-set stop position, a diamond 41 biassed so that its top engages the stop-face of the abutment member when the latter is in the stop position to determine the dressing position of the diamond and means for clamping the diamond in this position. The abutment member 16 is carried at the end of a spindle 15 which is axially-movable in a transverse bore in a tail-stock 3 movable on guideways 39 on the machine, the tailstock having a centre 38 which cooperates with a headstock centre 37 to support a rotatable workpiece 40 to be ground by a grinding wheel 4. The abutment member is urged towards the tailstock by a spring 64 and can be axially-moved in a sleeve 14 against this spring by feeding fluid pressure between collars 21, 22 having rebated faces 73, 74, the collar 21 being secured to the spindle 15 and collar 22 secured to the sleeve 14. The spindle can be rotated 180 degrees in the sleeve, so that the abutment, member is in the position shown or the position 16<SP>1</SP>, shown dotted, by a fluid-pressure operated piston 19 carrying a rack engaging a pinion 18 on the spindle. In the position shown dotted, the rebated part of one collar abuts the non-rebated part of the other, and in the alternative position the non- rebated parts abut each other. The sleeve carrying the spindle, and the piston 19 in its housing 26, can be moved in a radial direction with respect to the workpiece as a unit to position the stop face 17 in the pre-set position by a fine adjustment screw and nut arrangement. The diamond is carried by a holder 1 at the end of a shaft 2 which is urged towards the abutment member 16 by a spring 5 located in a piston 28 axially-adjustable relative to the tailstock by a screw 43 and threaded plate 44 secured to the tailstock. The shaft 2 has a flat portion 46 arranged to be engaged by a pressure pad 9, Fig. 3, which, in a recess in its upper face, receives a thrust piece 8 located in a similar recess 47 in a lever arm 7. The recess 47 is disposed between recesses 48, 49 on the arm, the recess 48 receiving a thrust piece 50 abutting an adjustable screw 10 and the recess 49 an element 52 carrying springs 6 bearing against adjustable screws 11, 12. The arm can be rocked anti-clockwise against the springs 6 by fluid pressure displacing a piston 13 in a cylinder 54 and causing a member 55 to engage the under side of the arm to release the pressure on the pad 9 and permit the shaft 2 to move under the control of the spring 5. The fluid pressure to the piston 13, the space between the collars 21, 22 and the piston 19 is fed from valves 68, 69, 70, respectively, actuated by cams 29, 30, 31 on a shaft 32 rotated by gearing 34, 77 from an electric-motor 33, the shaft 32 rotating at about 1 r.p.m. In operation, wear on the diamond is compensated by periodically bringing the tip of the diamond into engagement with the stop face of the abutment member which is accurately positioned by the fine adjustment screw. Initially, the valves 68, 69, 70 are closed, the abutment member in the position shown dotted, and the shaft 2 clamped in position, The motor 33 is then energised manually or automatically to rotate the cam shaft 32. The cam 30 actuates the valve 69 to supply fluid pressure to the space between the collars 21, 22 to move the former, and hence the spindle 15 in an outward direction against the spring 65. The cam 31 then actuates the valve 70 to supply fluid-pressure to the piston 19, the rack of which cooperates with the gear 18 to rotate the spindle 15 and place the abutment member with its stop-face 17, which may be of hard material such as boren or other carbide, in axial alignment with the shaft 2. The valve 69 is then released by the cam 30 to enable the spring 65 to urge the unrebated parts of the collars 21, 22 together to accurately position the stop-face 17 in the pre-set position. The shaft 2 is unclamped by the cam 29 actuating the valve 68 to permit fluid pressure to act on the piston 13 and enables the springs 5 to urge the tip of the diamond into contact with the stop-face. Finally, the cams actuate the valves so that the shaft 2 is re-clamped, and the spindle 15 urged axially-outward to disengage the stop-face from the diamond before it is rotated and returned to its initial position. Specification 722,444 is referred to.