Patent GB-422160-A (GB)
Title: Improvements in and relating to grinding machines
IPC: B24B47/20
Filed: 1934-04-30
Abstract: 422,160. Grinding-machines operated by fluid pressure. NORTON CO., New Bond Street, Worcester, Massachusetts, U.S.A. April 30,1934, No. 12967. Convention date, April 28, 1933. [Class 60] [See also Group XXIX] A grinding-machine slide carrying a work support or grinding wheel is traversed by a pressure cylinder or other fluid-pressure motor the amount of fluid supplied to which is controllable by a metering valve, thereby allowing the distance through which the slide is moved to be controlled by the amount of fluid admitted to the cylinder or other motor. The invention is described as applied to the control of the traverse movements of the grinding wheel of a surface grinder, the movements taking place at one or both ends of the stroke of the work table. Fig. 2 shows the machine largely diagrammatically, the parts above the work table 21 being shown at right-angles to their actual position. The grinding-wheel slide 26 is carried by a vertical slide 27, and is vertically adjustable on it to adjust the wheel to and from the surface of the work by a hand-wheel operating through gears and a screwed spindle (not shown). The horizontal movements of the slide 26 transverse to the work table 21 are made at the ends of the strokes of the table by a piston in a cylinder 98, to which pressure fluid is supplied in amounts regulated by a metering valve 160, whereby movements of the wheel substantially through its own width are obtained. Pressure fluid is supplied by a pump 42, both to the cylinder 98 and to a cylinder 35 which effects the reciprocation of the work-table 21. The fluid is supplied to the latter cylinder through a reversing-valve 44, the reversing-arm 58 of which is operated by adjustable tappets 84, 85 on the table at the ends of the stroke, and which moves the valve through gear segments 61, 62, Fig. 5, rock-shaft 63, and gear segment 64. A quick throw-over is secured by a lever 68 which engages a pin on a downward extension of the gear segment 64 and is urged to either side of the mean position by a spring 74. To control the motion, a piston 77 in a dashpot cylinder 78 is moved by a lever 80 secured on the rock-shaft 63. A throttle-valve 92 on the exhaust side of the reversing-valve allows the speed at which the table 21 is traversed to be varied. To effect, at the ends of the stroke of the table 21, the desired traverse of the grinding-wheel slide 26, a piston type control valve 168 is connected by a link. 170 to a lever 169 on the rock-shaft 63, so as to be reversed at each movement of the reversing lever 58. During each reversal of this valve, fluid is admitted by way of pipe 182, valve chamber 183, and pipe 178 to the chamber 179 of the metering valve 160, driving the piston 165 forwards and forcing fluid from the chamber 163, through a valve 161, pipe 103, balanced piston and reversing valve 102, to the cylinder 98. A screw 166 controls the stroke of the piston 165, and hence the amount of fluid forced to the cylinder 98, by which the distance of traverse of the wheel slide 26 is determined. When the piston valve 171 reaches the end of its stroke it cuts off the pressure fluid from the chamber 179 of the metering valve, and puts this chamber into communication with the chamber 163 on the other side of the piston by way of a valve 173, one or other of the pipes 180, 181, chamber 187 in valve 168, and pipe 188. The piston 165 of the metering valve is then returned by a spring, transferring the fluid in the chamber 179 to the chamber 163 and associated piping in readiness for the next actuation of the wheel slide 26. By setting the piston 176 of the valve 173 to uncover the ports leading to both the pipes 180, 181, as shown, an actuation of the slide 26 occurs when the table 21 is at each end of its stroke, but by setting it to close one or other of these ports the transfer of fluid from one side to the other of the piston 165 is prevented when the corresponding port of the valve 168 is opened, actuation of the slide 26 occurring therefore at one end only of the stroke of the table 21. The valve 161 may be set to three positions ; one, for the automatic intermittent traverse described of the slide 26, in which it allows fluid to pass from the chamber 163 to the pipe 103 ; a second, in which it admits fluid through a port 194 to the pipe 103, to move the slide 26 at a slow uniform rate for traversing the grinding wheel across a trueing tool; and a third, in which it cuts off fluid supply to the cylinder 98 for hand traverse of the slide 26. The reversing valve 102, is normally operated at each end of the traverse of the slide 26 by tappets 116, Figs. 10 and 11, engaging an arm 118 pivoted on a rock-shaft 119 carrying an upper pivoted arm 130 engaging a groove in the valve ; but when the slide is to be traversed by hand the valve 102 is rotated on its axis, this causing a cam 152 to lower the outer end of the arm 130, which through a push-rod 155 raises the arm 118 from the path of the reversing dogs 116. At the same time a pin 156, Fig. 10 engaging a cam recess in the side of the valve, brings the valve to a neutral position in which fluid may pass from one side to the other of the piston in the cylinder 98. The slide may then be hand traversed through pinion and rack gearing, not shown.