Patent GB-498295-A (GB)
Title: Fluid actuated wheel feeding mechanism for grinding or abrading machines
IPC: B24B47/20
Filed: 1937-07-01
Abstract: 498,295. Grinding. NORTON CO. July 1, 1937, No. 18306. Convention date, July 1, 1936. [Class 60] In a grinding-machine having a longitudinally movable rotatable work-support, and a grinding-wheel mounted on a transversely movable slide, the wheel is moved by fluid pressure means, controlled by electrical means, so as rapidly to approach the work, the speed of approach then being reduced to normal feeding movement, after which the feed is stopped, the grinding proceeding for a predetermined time without feed, and the wheel then being withdrawn from the work. The machine comprises a base 10 having ways 18, 19 on which is reciprocated, by rack gearing 25, 28, a work table 17 carrying the rotating work 21. The grinding-wheel 12 is carried by a slide 11 movable on transverse ways on the base by a nut 35, which is engaged by a feed screw 36 having a part 37 slidably keyed to a sleeve 38, and the sleeve may be rotated manually to adjust the wheel for wear, &c., through gearing 42..44, by a hand-wheel 41 provided with a micrometer mechanism 45. The slide 11 is moved up to and from grinding position and fed during grinding by a piston 52 connected to the screw 36 and movable in a cylinder 49 by fluid admitted under control of a valve 64 from a pump 62, the valve having thereon pistons 66 .. 69 and being operated by a stem 65 engaged by a lever 83 movable by a hand lever 80 or by a solenoid 125; when the valve is moved to the left, the wheel slide 11 is moved towards the work, and vice versa. During the first part of the movement of the wheel up to the work, fluid exhausting from the cylinder 49 through passage 72, has an unrestricted flow through a passage 71 in which is a valve 90, the valve being in the position shown. In order to slow down the speed of the slide 11 during grinding, the piston 91 of valve 90 is moved to the left by a solenoid 93 to cut off the fluid passage, so that the fluid passes through an adjustable needle valve 96 to a reservoir 60. The infeed of the wheel 12 is stopped positively, when the work is nearly to size, by an adjustable stop sleeve 100 mounted on an extended part of the piston rod 53, the sleeve engaging a surface 102 to stop the feed ; after the feed is stopped. the grinding continues without positive feed for a time determined by an electrically operated time delay relay 110, after which the valve 64 is moved to the right to withdraw the wheel from the work. These operations are controlled by switches 116, 118 operated by a cam 120 on the sleeve 100 and by a relay 114 and a switch 112 operated by a cam 113 on the valve stem 65, the sequence of operations being as follows. Movement of valve stem 65 to the left allows switch 112 to close and starts infeed movement of the wheel, which continues until the cam 120 closes switch 116, thereby energizing solenoid 93 and closing the valve 90, so that infeed continues slowly until the stop 100 engages the surface 102, and at the same time the cam 120 closes the switch 118, whereby the time delay 110 is started. Grinding continues until the time relay functions to operate an electromagnet 115, which moves the relay arm 114 to de-energize the solenoid 93, and at the same time the time relay closes the circuit of solenoid 125, which moves the valve 64 to the right to withdraw the wheel 12 from the work; the switch 112 also is opened, rendering the electrical control inoperative. British Specification 6784/01, [Class 60], and U.S.A. Specifcation 1,969,997 are referred to.