Patent GB-583528-A (GB)
Title: Improvements in or relating to grinding or abrading machines
IPC: B24B53/07
Filed: 1944-04-26
Abstract: 583,528. Trueing grinding - wheels. SHEFFIELD CORPORATION. April 26, 1944, No. 7810. Convention date, April 26, 1943. [Class 60] Apparatus for trueing a grinding-wheel by means of a crusher wheel, described as for shaping annular ribs on the grinding-wheel, comprises means for moving the crusher-wheel up to the grinding-wheel, feeding the crusherwheel slowly and then withdrawing it. The grinding-machine comprises a frame 10, Fig. 1, carrying the grinding-wheel 11, and the crusherwheel 12 is mounted for free rotation in a bracket 13 slidably guided in the frame 10. The bracket 13 is adjustably carried by a plate 16 having a head 17 and guided for movement towards and from the wheel 11 between the bracket 13 and the wall 21 of the frame 10, the adjustment of the bracket being effected by a screw 18 rotatably mounted in the head 17 and engaging a nut 19 on the bracket 13 ; a scale 30 on the head 17 co-operates with a post 30<1> on the frame 10 to indicate the position of the head. In the wall 21 is a vertical slot having movable therein a bar 23 secured to the plate 16 and carrying by studs 25 a plate 26 on each side of which is a roller 27 ; the rollers engage a double plate cam, the cam portions 28, 29 of which move the plate &c. up and down, thus also moving the crusher-wheel towards and from the wheel 11. The cams are rotated by means of a motor 31, which drives, through reduction gearing 32, a shaft 33 on which is secured a ratchet-wheel 34 adapted to be coupled to a drive plate 35 by a pawl 36, Fig. 7, pivoted at 37 on the plate 35 and acted upon by a spring 38 and by a pawl 39, controlled by a spring 40, which normally holds the pawl 36 free of the ratchet-wheel 34, the pawl 36 being freed by a solenoid 42, which acts on the free end of the pawl 39. The drive plate 35 then can be rotated through one rotation, a cam projection 43 on the plate then engaging a finger 44 on the pawl 39, which stops the rotation; the pawl 36, just before the above action takes place is lifted, by the finger 44, out of engagement with the ratchet-wheel 34. The drive plate 35 is secured to a shaft 46 mounted in the frame 10 and carrying a cam 48, Fig. 6, which controls a pawl 49 to open and close a switch 51 to stop or start the motor 31; the shaft also carries a cam 52 serving to control a switch which when closed energizes a relay to close a switch causing the grinding- wheel motor to rotate the wheel at low speed. The shaft 46 also carries a cam 57, which operates the screw 18 through a lever, the upper end of which engages a plate portion 59 of a ratchet feed yoke 60 rotatable on the screw and carrying a pawl 61 engaging a ratchetwheel 62 fixed to the screw. The amount of rotation of the screw is adjustable by the provision on the lever 58 of an arm 71 adjustable lengthwise of the upper arm 70 of the lever, and by the provision on the upper end of the arm 71 of a laterally adjustable upper end portion 74 which engages the plate 59; the rotation of the screw is indicated by a scale 77 on a dial 78 on the screw and a mark 80 on the head 17. In operation, a switch is closed, causing energization of the solenoid 42 so as to engage the pawl 36 with the ratchet-wheel 34 and at the same time to close the switch 51 to start the motor 31. The drive plate 35 thus is started on a 360 degrees movement, and during the first 50 degrees rotation the cams 28, 29 cause the crusher-wheel 12 to be lowered to engage the wheel 11 ; the cam 52 then causes the closing of the switch to start the wheel 11 rotating slowly. During the next 200 degrees of rotation, the cam 57 operates the ratchet-wheel 62 to rotate the screw 18 to feed the crusher-wheel into the wheel 11, the succeeding portion of the cam 57 is concentric to its axis, so that feed of the crusher-wheel ceases. The cams 28, 29 then lift the crusherwheel away from the wheel 11, the cam 52 opens the starting switch and at the end of the 360 degrees movement the pawl 49 drops to open the switch 51 and the plate 35 is latched by the pawl 39. The screw 18 may be adjusted manually, for example, when treating new or ungrooved grinding-wheels, by application of a wrench to a square head 22 on the screw.