Patent GB-684376-A (GB)
Title: Bar grinding apparatus
Inventor: ELLISON STANLEY RUSSELL
IPC: B24B7/12
Filed: 1951-02-14
Abstract: 684,376. Grinding. DRIVER CO., W. B. Feb. 14, 1951, No. 3582/51. Class 60. A machine for grinding a bar B comprises a grinding wheel W, Fig. 2, which is rotatable at substantially constant speed about a horizontal axis and movable vertically into and out of grinding position, means for rotating the bar at substantially constant speed and feeding it endwise at a substantially constant rate with its upper surface in pressure contact with the wheel, pneumatic ram means for moving the wheel into and out of grinding position, and means for automatically varying the pressure of the pneumatic means in accordance with the contour of the bar so as to maintain a substantially uniform depth of cut over the surface of the bar. The wheel W is mounted on a pivoted lever L movable by two doubleacting rams 1, 2 to bring the wheel into and out of engagement with the bar B which is rotated and fed across the wheel. The wheel W, together with a pulley E and counterweight F, is mounted on one end of the lever L and is driven by a belt D from a motor M on a spring-mounted platform P; a counterweight C for the wheel assembly is mounted on the opposite end of the lever. Valves V3, V4, Fig. 3, control the supply of air to opposite ends of the rams 1, 2 and are actuated by solenoids Sl, S2, S3, S4 arranged in a circuit under the control of switches 22, 23, 24 actuated by the bar B. The switches 22, 23 are disposed on opposite sides of the wheel Wand each is adapted to be closed when the advancing bar B depresses a spring- urged lever 20, 21. The switch 24 co-operates with the periphery of a cam 31 which is mounted for free rotation and, for dealing with bars of square cross-section, is constructed as shown in Fig. 4 with spring fingers 30 for gripping the bar and high parts 31a. Initially, the solenoids S3, S4 are energized and the solenoids S1, S2 deenergized so that the air supply to the rams raises the wheel. In operation, the advancing bar B actuates the switches 22, 23 in turn and thereby acts through relay switches 40, 43, 45 to de-energize the solenoids S3, S4 and energize the solenoids S1, S2 whereby the rams lower the wheel on to the bar; at this stage, the rotary cam 31 is so positioned that the switch 24 is in the dotted line position of Fig. 3. The advancing bar next engages the cam 31 which is rotated thereby so that its high and low parts actuate the switch 24 to energize alternately the solenoids S2, S4 and cause the ram 2 alternately to supplement and diminish the effect of the ram 1 with a corresponding alteration in the position of the wheel W; with the cam 31 shaped as shown in Fig. 3, the minimum total pressure is obtained when the corners of the bar are being operated upon. When the bar B clears the first lever 20, the switch 22 is opened and the solenoids are restored to their original condition to raise the wheel. When dealing with bars having more than four sides, the number of raised areas 31a and spring fingers 30 on the cam are correspondingly increased, and when round bars are being ground the switch 24 is disconnected.