Patent GB-463334-A (GB)
Title: Improvements in hydraulically operated grinding and abrading machines
IPC: B24B47/06
Filed: 1935-08-20
Abstract: 463,334. Hydraulic transmission of power. NORTON CO. Aug. 20, 1935, No. 23377. Convention date, Aug. 23, 1934. [Class 69 (ii)] [Also in Group XXIII] Relative movement between the work table 11 and the grinding-wheel 15 of a grinding - machine is effected by means of a piston and cylinder 30, the fluid supply to which is controlled by a reversing valve 45 actuated by the said movement to admit fluid alternately to opposite ends of the cylinder and a valve 90 which in one position throttles the fluid supply to control the speed of movement and in another position allows free passage of the fluid from one end of the cylinder to the other so as to enable work table 11 to be operated manually through rack-and-pinion gearing by a hand wheel 120. In the form illustrated, the cylinder 30 is attached to the work table and is movable relatively to two spaced pistons 31, 32 connected by hollow piston rods to hollow brackets 35, 36 on the machine base 10. The hollow brackets 35, 36 are connected by pipes 68, 69 to ports 64, 65 in the valve 45. A member 49 formed with spaced pistons 50 ... 54 is adapted when displaced from its mid-position to connect one of the ports 64, 65 to a port 59 or 60 supplied with fluid from a pump 42 and the other to an exhaust port or pipe 95 so as to cause movement of the table 11. At the end of its movement adjustable dogs 130, 131 on the table 11 operate a lever 133 having an arm 138 formed with an aperture 144 engaged by a pin 145 on a pivoted arm 139 connected to the member 140. The member 49 is thereby brought back to its mid-position and is then moved slightly beyond its mid-position by a spring 155 arranged between the two arms 138, 139. This movement causes an inequality in pressure in two chambers 79, 80 between the end pistons of the member 49 to which fluid can flow through ports 75, 76 and 77, 78 and escape through ports 81, 82 to the reservoir 40 in the machine base. The member 49 consequently continues its movement to its extreme position and reverses the direction of fluid flow to the cylinder 30. The valve 90 comprises a stem 91 formed with pistons 92, 93 and operated by a lever 103. In the full line position, Fig. 2, the valve throttles the exhaust fluid flowing from the valve 45 through a V-shaped port 94 to a pipe 96 leading to the reservoir 40. The end of the piston 93 is preferably inclined so that a fine adjustment may be obtained by rotating the valve stem by knob 99. A screw 102 on a non-rotatable sleeve 106 mounted on trunnions 108 in the lever 103 affords an adjustable abutment for a surface on a dial carried by the knob 99. A spring pawl 101 engaging serrations 100 retains the stem in its adjusted position. When the valve 90 is moved to the dotted position a chamber 112 between the pistons 92, 93 connects pipes 110, 111 leading to the pipes 68, 69 to allow manual transverse of the table. The grinding wheel 15 and its supporting slide 16 may be fed to and from the work support by pawl-and-ratchet wheel mechanism such as shown in Specification 6784/01, [Class 60]. As shown, the pawl 166 operating a feed wheel 126 to rotate the feed screw 129 of the slide 16 is pivoted to a slide 164 which is connected by a link 163 to a piston 161 slidable in cylinder 160. At each operation of the lever 133 an adjustable arrow point 173 at its lower end operates a spring- pressed valve 171 to cause reciprocation of the piston 161. The extent of the feeding movement may be regulated by means of an adjustable stop 190 on the link 163 adapted to engage a fixed stop 192. In order to ensure that the work makes a complete turn before the table starts moving in a reverse direction, the pipes 68, 69 may be connected by pipes 207, 208, Fig. 9, to a cylinder 206 containing a shuttle piston 205. When the valve 45 suffers reversal, the work table will remain stationary until the piston 205 has moved from one end to the other of the cylinder 206, this movement being slowed down at the ends of its stroke by conical projections 211, 212 entering chambers 213, 214 in the cylinder. The pipes 207, 208 are fitted with shut-off valves 209, 210. Air entrapped on leaking into the fluid system may be removed through valve-controlled bleeder ports 220, 221 in the cylinder 30.