GB715247A - Improvements in grinding machine with crush wheel dressing mechanism - Google Patents

Abstract

715,247. Control of several motors. BRYANT CHUCKING GRINDER CO. Sept. 19, 1952 [Oct. 5, 1951], No. 23603/52. Class 38(3) [Also in Group XXIII] Six motors 1M ... 6M, Fig. 18, for driving certain parts of a grinding machine (see Group XXIII) are controlled by switches and relays in a lowvoltage control circuit so as to provide for automatic operation of the machine. The closure of switches 270, 285, Fig. 18, serves to energize through controls 2m, 4m the high-speed motor 2M for driving the grinding wheel, and the motor 4M for driving a cam shaft which controls the movement of the grinding wheel carriage to and from operative positions. Further cams on this cam shaft act through switches LS4, LS6, control 5m, 6m and relay CR2 to start the work-spindle motor 5M, open a clutch between the motor 4M and the cam shaft, and energize a motor 6M for driving a second cam shaft controlling the feed movement of the work carriage. The second cam shaft, towards the end of one revolution, operates switches LS7, LS12 and relays CR1, CR2 to re-engage the clutch for the drive of the first cam shaft and stop the drive of the second cam shaft. The two cam shafts combine in alternate operation to provide for a number of grinding cycles until a pre-set counter CNTR, which is engerized once every revolution of the first cam switch by the actuation of the switch LS8, records the number of grinding cycles for which it has been set. The counter then acts through a switch 336 to stop the grinding- wheel motor 2M and through a switch 335, relay CR2, CR4, and control 3m to stop rotation of the main cam shaft, open switch 312 to prevent operation of the motor 6M, and start the motor 3M for driving a cam shaft controlling mechanism for dressing the grinding wheel. A cam on this cam shaft also acts through a flexible cable 88, Fig. 15, to actuate a clutch whereby the grinding wheel is then driven by a low-speed motor 1M. This cam shaft is effective at the end of one revolution to render the dressing mechanism inoperative, restore the high-speed drive of the grinding wheel re-set the counter C to zero and stop the motors 1M, 3M with the parts in their initial positions. The motor 7M is started at the beginning of an operation to circulate lubricant and coolant. The low-speed motor 1M, Fig. 15, is disposed on the casing 2a of the high-speed motor 2M, upon. the armature shaft 3 of which the grinding wheel 3 is mounted. The motor 1M has a belt-and-pulley drive 51 with a hollow shaft 54 which is journaled in the end wall 58 of the casing and is mounted at its inner end with a spider 60 carrying pivoted friction shoes 62 urged by springs 63 against a pulley 67 on the shaft 3 when the motor 2M is de-energized. When the motor 2M is energized, the friction shoes are rendered inoperative by pins 73 forced outwardly of the spider by a coaching pin 70 which is moved axially in the shaft 54 by a lever 75 operated by the cam-controlled flexible cable 88. Specification 684,914 is referred to.