Patent GB-544509-A (GB)
Title: Improvements in or relating to centreless grinding machines
IPC: B24B5/35
Filed: 1940-08-19
Abstract: 544,509. Centreless grinding. AKTIEBOLAGET MALCUS HOLMQUIST. Aug. 19, 1940, No. 13211. Convention date, June 16, 1939. [Class 60] In a centreless grinding-machine, hydraulic control-means for the slide carrying the counterroller comprises a pair of connected, mechanically-driven rotary valves for coupling alternately to the pressure and suction sides of a pump the opposite ends of a cylinder containing a piston for operating the slide. The control-means may be arranged to control also the slide carrying the grinding-roller. In the apparatus shown in Figs. 1, 2 and 8, a work-piece 3 is acted on by a grinding-roller 1 and a counterroller 2 and is supported by V-surface on a rest 4 mounted in a holder 5. The work-pieces are piled in a magazine 79 and the bottom workpiece is periodically fed into the space between the rollers and into contact with an abutment 89 by means of a rod 10. The roller 2 is mounted on a slide 8 provided with a collar 12 which engages a rod 13 having a threaded part 14 co-operating with the rod 15 of a piston 16 mounted in a stationary cylinder 17. Rotation of the piston rod is prevented by an arm 23 and groove 24. The piston-rod is provided with a hard-metal piece 60 for co-operation with a cam 56 on a shaft 26 which is driven through worm-gearing 27 by an electromotor. Valves 29, 30 on the shaft work in a casing 32 which is connected through ports 34 and 46, 47 with the pressure and suction sides of an oil pump. The valves 29 and 30 are divided by radial walls into compartments 40a, 41a and 40b, 41b having ports 42a, 44a and 42b, 44b respectively. The valve-compartments can communicate through pipes 54, 55 with the cylinder 17, and through pipes 76, 76 with a cylinder 71 containing a piston in connection with the rod 10. The feed-stroke of the rod.is'limited by adjustable screw-abutments. When the pipes 54, 75 and 55, 76 communicate with the compartments 41a and 41b respectively, the piston 16 moves the roller 2 away from the roller 1, and the rod 10 is retracted. When the pipes.communicate with the compartments 40a and 40b, the piston 16 urges the roller 2 towards the roller 1, and the rod 10 feeds a work-piece into the space between the rollers. During the feedmovement, a high part of the cam 56 prevents movement of the piston 16. The cam then permits the roller 2 to press the work-piece into contact with the roller 1 during rough-grinding, and afterwards permits slight further movement during fine-grinding. The compartments 41a, 41b are smaller than the compartments 40a, 40b, and thereby cause the retractionstrokes of the pistons to be performed more quickly than the feed-strokes. The pipes 55, 76 are provided with valves for regulating the speed. The roller 2 is adjusted in accordance with the size of the work-piece by screwing the rod 13 into or out of the piston-rod 15 by means of a hand-wheel 65, the setting being indicated by a graduated disc 66 on the rod. When the roller 2 is retracted, the finished workpiece rolls down a bevel 7a on the holder 4 into a shoot 93. The holder is vertically adjustable by means of a hand-wheel 92. The feeding- device may be duplicated to provide for simultaneously feeding work-pieces from both sides of the rollers. The slide of the grinding-roller 1 may be provided with hydraulic operating- means similar to that for the slide 1 and arranged to act simultaneously or in alternation therewith.