Patent GB-630814-A (GB)
Title: Improvements in crush dressing mechanism
IPC: B24B53/07
Filed: 1947-07-25
Abstract: 630,814. Crush dressing. JONES & LAMSON MACHINE CO. July 25, 1947, No. 20077. Convention date, July 26, 1946. [Class 60] [Also in Group XXXVII] A grinding-machine includes a grinding wheel 2, wheel turning mechanism comprising a crushing roll 11 supported for rotation about an axis substantially parallel to that of the wheel and for motion toward and from the wheel, means biasing the roll to a position retracted from engagement with the wheel, and a fluid-pressure motor for pressing the roll against the wheel, the motor having a bleeder port 69. The machine has a cradle 1 with a tubular extension 3 to receive an angularlyadjustable cylindrical casing 4. This casing has a pair of transverse partitions 6 and 7 provided with bushings 8 for slidably mounting a ram 9 on which the roll 11 is journalled. A flexible diaphragm 12 prevents detritus entering the bushings. A nut 14 secured to the near end of the ram is in threaded engagement with a rod 15 which is secured to a piston 16 and has a splined portion to carry a gear 20 driven from a shaft 27 through a gear train. This shaft, which forms part of the wheel-feed mechanism, has a threaded portion 28 in engagement with a lug on the machine frame and is driven by a gear 31 meshing with a long gear 32 driven from a gear 34 turned in time with the traverse of the work so as to displace axially the ram with respect to the piston 16. The latter applies crushing pressure to the roll when its cylinder 17 is fed with oil from the interior of the casing 4 through a valve chamber 43 from a pump driven by a motor 50. The casing carries at its end a cap 80 which is secured by bolts 81 passing through arcuate slots 82, Fig. 2, and located by a guide bar 83 on the machine frame. Angular adjustment of the casing with respect to the extention 3 is effected by loosening bolts 5a and 81 and rotating a pinion 87 journalled in the cap 80 and meshing with an arcuate rack 88 secured to the casing, scales 91 and 92 showing the extent of adjustment. The cap 82 supports a shaft 101 carrying an adjustable stop 114, a dog 102 and a lever 100 which engages two switches 15LS and 16LS. An abutment 105 engaging the dog and adjustably secured to the extended rod 15 rotates the shaft to operate the switches when the piston 16 moves. The means for biasing the roll 11 away from the grinding wheel comprises two springs 70, Fig. 6, connected to the ram through a clamping ring 75 which slides along a guide-bar 79 and is clamped in the desired angular position on the ram. In an alternative construction, the clamp 75 has a cursor co-operating with a scale on a ring clamped to the ram, and the roller 11 is mounted for adjustment in a direction transversely of the length of the ram by means of a screw and slide mechanism. To effect dressing, a switch is opened to stop a motor driving a coolant pump and to brake the grinding-wheel motor. A second switch is closed to start the motor 50 and to complete a safety circuit which prevents premature connection of the wheel motor with a rectifier from which it receives current during the dressing operation. When the wheel motor .has come to rest, a third switch is closed to connect the wheel motor with the rectifier for slow reverse running and to start the coolant-pump motor. As the ram advances to crush the wheel to size, it operates the switches 15LS and 16LS to start a timing device which, after a predetermined period, stops the motor 50 and disconnects the wheel motor from the rectifier. The ram is now retracted again operating the switches 15LS and 16LS to re-connect the wheel motor with the d.c. supply so that grinding speed is resumed.