GB689049A - Improvements relating to grinding machines - Google Patents

Abstract

689,049. Grinding machines. JONES & SHIPMAN, Ltd., A. A., and HOULDSWORTH, J. Feb. 19, 1951 [March 24, 1950], No. 7438/50. Class 60. [Also in Group XXIX] A grinding machine includes a pivotally mounted grinding wheel head 3 connected by a link 11 to a lever 12 which is applied against a slidable cam 16 to control the rate of infeed until movement of the head is arrested by a closed stop 18, whereafter this control is disengaged. The grinding wheel 1 is driven by an electric motor 6 mounted on the head 3 which is angularly displaced about a pivot 5 by a piston 8 to feed the wheel into the work. The lever 12 carries a roller 15 bearing on the cam 16 which is displaced by a hydraulic piston 22. Part of the operative surface of the cam may be formed by a lever 20 adjustably inclined to alter the rate of feed over a portion of the travel of the cam. A change in the speed of the cam, to cause a change in the rate of feed of the grinding wheel, may also be effected by a microswitch 21 operated by a subsidiary cam secured to the cam 16. When this switch is closed, a solenoid 58 is energized and a valve 56 displaced to the right to supply fluid to a plunger 51 which bears on an adjustable screw 45 governing the displacement of a throttle valve 30 in the exhaust line from the cylinder of piston 22. When the switch is open, the valve 56 is displaced to the left by a spring 63 to supply fluid to a plunger 49 which bears on a second adjustable screw 46 to give the throttle valve 30 a different setting and hence a different speed to the piston 22. After the arm 4 has engaged the stop 18, the cam 16 continues to move to the right until it is out of contact with the roller 15 which forms part of an electric circuit energizing a solenoid 35 which is now de-energized to allow a pilot valve 34 to be moved to the left by a spring 37. The movement of the pilot valve displaces a reversing valve 23 to reverse the piston 22 which now moves rapidly to the left, the throttle valve 30 being displaced to maximum discharge position by a plunger 50 controlled by a valve 56. The latter normally connects the plunger 50 to exhaust, but may be displaced by a solenoid 67 to connect it to the pressure supply. A rapid infeed of the grinding wheel may be obtained by energizing the solenoid 67 during the rightwards travel of the piston 22.