Patent GB-1285852-A (GB)
Title: Grinding machines
IPC: B24B49/18
Filed: 1971-04-19
Abstract: 1285852 Grinding TOYODA KOKI KK 19 April 1971 [11 March 1970] 23510/71 Heading B3D A multi-wheel grinding machine comprises supporting means 2, 3 in a base 1 for rotatably supporting a workpiece 5 having a plurality of portions 5a, 5b to be ground, a plurality of sizing devices 6a, 6b for measuring the diameters of the portions, a wheel slide 7 mounted on the base and having a plurality of brinding wheels 9a, 9b, first feeding means for moving the slide towards and away from the workpieces a plurality of dressing means 16a, 16b slidably mounted on the wheel slide, a second feeding means connected to each of the dressing means, and a control system connected to the second feeding means for advancing the dressing means in accordance with signals supplied from the sizing devices. The workpiece is mounted between head and tail stocks 2, 3 on a table 24 which is adjustable about a pivot 25 on the base 1, the workpiece being rotated by a motor 4. The grinding wheels 9a, 9b are mounted on a shaft 8 which is driven by a belt drive 10 and carried by the slide 7 movable along guideways 47. A slide base 19 is carried by the wheel slide 7 and supports a slide 22 which is movable towards and away from the grinding wheels by rotation of a lead screw 18 and ratchet mechanism 17 and adjustable carries dressing heads 12a, 12b, each head having a rotatable dressing wheel 16a, 16b. The wheels are connected together by a splined shaft 90 and universal joint 91 and are r ated by a belt 14 driven by an electric motor 13. Each head is movable by a respective ram 23 engaged by a head screw 21a, 21b, driven by a ratchet mechanism 20a, 20b. The dressing heads are thus movable in unison by the ratchet mechanism 17 or individually by the ratchet mechanisms 20a, 20b. The mechanism 17 has one pawl and ratchet for advancing the slide and a second for retracting the slide, the ratchets being engaged by a rack on a double acting piston and the degree of engagement of the pawls with the ratchets being adjusted by arcuate members interposed between the pawls and ratchets. The wheel slide 7 has a nut 46 engaged by a lead screw 45 which is axially movable by a piston 43 in a cylinder 42 for fast feed and is rotatable for fine feed. A gear 41 on the screw engages a spline gear 40 connected by a gear 39 to a gear 38 on a shaft 37. The front end of the shaft 37 is connected by gearing 33, 32 to a shaft 34 on which is keyed a gear 26 rotatable by a hand wheel 11 and formed with one part 29 of a clutch, the other part of which is rotatable on the shaft 34 and formed with a pinion 30a engaged by a rack 31 on an hydraulic actuator 71. The gear 26 is also formed with a hollow piston 28 which is urged by a spring 28a to engage the clutch parts but can be acted on by hydraulic pressure to disengage the clutch parts whereby the slide 7 can beadvanced manually or automatically. When the clutch parts are disengated, the wheel slide can be advanced to compensate for wear or dressing of. the wheels by movement of a rack 52 by an hydraulic actuator rocking a piece 48 carrying a pawl 51 which engages a pinion 49 on the shaft 37, an arcuate member 50 being adjustable to determine the number of teeth on the pinion engaged by the pawl. In operation, the wheel slide is advanced at a rapid rate by actuation of the hydraulic actuator 42 and then at a rough grinding speed by the actuator 71. The sizing devices are at this time advanced into the workpiece. If the devices produce the same signals at the same time, the actuator 71 is controlled to produce a fine feed until the sizing devices indicated a desired finish size whereupon the feed is stopped for a predetermined time before retraction. The wheels may then be dressed by actuation of the ratchet mechanism 17 advancing both dressing heads 12a, 12b and the slide 7 is advanced by the actuator moving the rack 52 of the pawl and ratchet mechanism 49, 51, the clutch 29, 30 at this time being disengaged. The dressing heads are then retracted at a fast rate by the mechanisms 17. If, during grinding, one of the sizing devices indicates that one portion of the workpiece has reached a predetermined size before the other, in addition to the ratchet mechanism 17 advancing both dressing heads, the ratchet mechanism of the dressing head associated with the wheel grinding that portion is actuated to advance that head to dress and reduce the diameter of that wheel whereby both portions are ground to the same size.