Patent GB-473963-A (GB)
Title: Improvements in and relating to cam grinding machines
IPC: B24B19/12
Filed: 1936-03-19
Abstract: 473,963. Cam-grinding machines. NORTON CO. March 19, 1936, No. 8290. Convention date, March 27, 1935. [Class 60] A cam-grinding machine of the kind in which a rotating grinding wheel and a rotatable work support are relatively movable transversely to grind a work blank to a predetermined size and contour is fitted with a controlling device actuated in timed relation to cause the separation of the wheel and work to take place when the wheel is in engagement with a predetermined portion of the work such as the high point or nose of a cam. In the machine shown a grinding wheel 13 mounted on a slide 11 is fed towards and away from the work by a hand-operated wheel 21 fitted with a micrometer - adjusted abutment 22 engaging a stop pawl 23 when the work is to size, as described in Specifications 6784/01, [Class 60], and 348,180. The work consisting of a shaft 45 carrying a number of cams 46 to be ground in succession is secured in alignment with a master camshaft 44 mounted in a headstock 43, carried by a rock-bar 40 on a sliding table 30. During its rotation by a belt pulley 53, the cam -shaft 44 is held in engagement with a follower roller 48, journalled in a headstock frame 52, by a spring 67 contained in a cylinder 65 operating a lever 61 on the bar 40. In each revolution of the cam-shaft the bar 40 is rocked once and a lug 143 on the bar 40 rocks against the resistance of a spring 185, a plate 138 carrying a pawl 139. The pawl 139 operates a ratchet wheel 133 which is prevented from returning by a pawl 145. The ratchet wheel 133 carries an angularly adjustable mercury switch 130 which, when the ratchet wheel has reached a predetermined position, closes the circuit of a solenoid 121 operating a valve 83 to admit fluid from a pump 70 to a chamber 125 in a cylinder 84. A piston 126 in the chamber 125 is thereby moved to depress the lever 61 into the position 61A and to operate the rock-bar 40 to withdraw the work from the grinding wheel. On the operation of the feed wheel 21 to move the grinding wheel rearwardly, the feed screw gear 18 turns through a lost-motion friction. device 78, a shaft 77 operating valve pistons 80, 81 to admit fluid from the pump 70 to the upper part of the cylinder 84. A piston 85 is thereby operated to depress further the rock-bar 40 into position 61B whereby the master cam shaft is moved clear of the roller 48, and the plate 138 is moved into a position in which the pawls 139, 145 are disengaged from the ratchet wheel 133. The ratchet wheel 133 is then returned to its initial position by a spring 151, this movement being cushioned by a projection 154 on the ratchet wheel engaging a spring-pressed plunger 153 forming part of a dashpot 157. The table 30 can now be shifted to bring another cam 46 opposite the grinding wheel, the roller 48 being brought opposite the corresponding master cam by an indexing mechanism constructed as described in Specification 348,180. When the wheel 21 is again operated to feed the grinding wheel towards the work the shaft 77 moves the pistons 80, 81 to allow fluid to exhaust from the cylinder 84 through a pipe 91 to the reservoir and the rock-bar 40 to move until the master cam engages the roller 48. The controlling device may be placed out of action by operating a lever 165 to move the pawl plate 138 and ratchet wheel 133 out of the path of the lug 143.