GB1049583A - Improvements in and relating to machine tool feed mechanisms - Google Patents

Abstract

1,049,583. Grinding. LANDIS TOOL CO. Feb. 19, 1964 [Feb. 21, 1963], No. 7001/64. Heading B3D. A feed control mechanism for a machine tool having a work support 21, a tool 12 mounted on a support 11 slidably mounted on a bed 10, and feeding means for advancing and retracting the tool support relative to the work support, comprises a piston 71 and cylinder 70 movable relative to one another by movement of the tool support, a supply of fluid under pressure connected to the cylinder, means to effect adjustment of the feeding means while the tool support is held against movement by the pressure in the cylinder, and means 100 to connect the cylinder with a lower pressure. As described, the machine tool is a centreless grinder having a grinding wheel 12 rotatably mounted on the support 11, a control wheel 15 on a support 16, and a work-rest blade 20 mounted on a base 21 on the bed 10. The feeding means for the tool support 11 consists of a feed screw 30 which is rotatable and axially movable in the bed 10 and has a piston 31 in a cylinder 32. The screw engages a worm 36 at the lower end of a vertical shaft 35 in the support 11, the upper end of the shaft having a wheel 40 engaged by gearing on a hand wheel 45. The hand wheel is also rotatable by gearing 54, 55 driven by a rack 53 on the rod 52 of a piston 50 in a cylinder 51. An adjusting screw provides fine adjustment means for the hand wheel. The feed screw 30 is rotatable by means comprising a gear 105 which is keyed to the screw 30 and engages a worm 106 on a shaft 107 having a worm-wheel 108 meshing with a worm 109 on a shaft 115. A ratchet 116 is mounted on the end of the shaft and is rotatable in one direction or the other by a feed advance pawl 117 and a feed retract pawl 118, the pawls being actuated by fluid motors. The forward advance of the wheel support 11 is controlled by the piston 71 in the cylinder 70 engaging a stop 72 on the bed 11. In operation, fluid pressure is supplied to cylinder 32 to move piston 31 and the feed screw 30 to the left, Fig. 4, to the end of its movement. Fluid pressure is then supplied to cylinder 51 to move piston 50 and effect rotation of shaft 35 along the screw 30 until piston 71 engages stop 72 and a cam 80 operates a feed completion switch 81 to energize a solenoid 82 which moves a valve 83 to supply fluid at a pressure determined by a relief valve 85 to a valve 90 and the cylinder 70, the pressure being such as to prevent further movement of the wheel support 11 to enable spark-out or round-out to be effected. In this position of the support a series of workpieces may be fed through the machine. If a post-process gauge shows that the workpieces are being ground oversize, a valve 100 is actuated by the operator to connect cylinder 20 briefly to exhaust to permit advance of the wheel support by an amount corresponding to the oversize and shown on a gauge 130. If the workpieces are ground undersize, the valve 90 is actuated by the operator to connect cylinder 20 to a higher pressure determined by relief valve 92 to move the wheel support an amount corresponding to the undersize. With the valves 90 and 100 in the position shown and the valve 83 in its alternative position, the feeding means may be adjusted by rotation of the shaft 30 by the advance pawl 117, or by rotation of the hand wheel 45, without movement of the wheel support.