GB793638A - Improvements in or relating to the grinding of ring-like workpieces - Google Patents

Abstract

793,638. Grinding. LANDIS TOOL CO. Aug. 2, 1955 [Aug. 2, 1954], No. 22111/55. Class 60. A method of grinding ring-like workpieces to their external diameter includes rotating the workpiece, feeding a grinding wheel against the external peripheral surface of the workpiece, stopping the feed of the wheel at a predetermined point and then grinding the said surface to a predetermined diameter by feeding the workpiece against the grinding wheel until the desired diameter has been reached. A workpiece such as the inner race of a ball bearing with its end faces ground parallel and the internal surface ground to predetermined size, has its external surface ground to the desired diameter and concentric with the internal surface in a machine comprising a grinding wheel 18 carried by a slide 15 fed by a piston 20 in a cylinder 19 under the control of a valve 24 which is operated by handle 25 to initiate the feed. The internal surface of the workpiece W is engaged by shoes 11, 12 on an arbor 10 mounted in arm 10a movable from loading position to operating position in which one end face of the workpiece is engaged by a magnetic chuck 14 on a rotating spindle 13. A workpiece feeding shoe 32 is carried by a bar 33 mounted at the upper ends of flexible steel members 34, 34 anchored to a block 35 secured to the machine base. A compression spring 38 urges the bar 33 towards the workpiece. A shaft 41 has fixed to one end an arm 42 co-operating with a pin 40 mounted in a block 39 secured to the rear end of the bar 33 ; fixed to the other end of the shaft 41 is an arm 42a connected to the core of a solenoid 47. During the feed of the grinding wheel the solenoid 47 is energized, thus holding the bar 33 retracted from the workpiece, the workpiece being then located by both shoes 11, 12. The grinding wheel feed ceases when the slide 15 contacts a stop 27 ; this closes a fluid exhaust port 28 in the stop 27, the consequent rise in fluid pressure operating a switch 50 to deenergize the solenoid 47 thus permitting the spring 38 to move the bar 33 into contact with the workpiece which is thus rocked about the shoe 11 and fed towards the grinding wheel. When the desired diameter is reached the feed ceases due to contact of the block 39 on the bar 33 with an adjustable stop 49. The operation of the switch 50 at the end of the grinding wheel feed also brings into circuit a timer relay 51 set to close a switch 52 after the feed of the workpiece has ceased, closure of switch '52 energizing solenoid 53 to shift the valve 24 to cause withdrawal of the grinding wheel to its retracted position. As the port 28 is uncovered, the switch 50 returns to normal and the solenoid 47 is energized to withdraw the bar 33 from the workpiece, thus completing a cycle. Specification 712,024 is referred to.