Patent GB-662205-A (GB)
Title: Automatic feed mechanism for grinding machines
IPC: B23F23/12
Filed: 1949-08-12
Abstract: 662,205. Grinding gears &c. GEAR GRINDING MACHINE CO. Aug. 12, 1949, No. 21079/49. Class 60 Feed mechanism for grinding-machines comprises an axially-movable member G, Figs. 3 and 4, connected with the member to be fed, a shaft L, Fig. 4, rotatable about an axis transverse to that of the member G, an eccentric portion L' on the shaft L having a connection K<SP>1</SP> with the member G, a pinion N on the shaft L meshing with a rack N<SP>1</SP>, a hydraulic cylinder-and-piston motor 0, 0', Fig. 9, for actuating the rack, and a fluid-metering device U adapted to operate the hydraulic motor step by step to communicate a corresponding movement to the member G. The work, e.g. a gear, is indexibly mounted between a headstock and tailstock, and, as shown in Fig. 3, the grinding-wheel D is mounted on a head E carried by a column F on a reciprocating carriage C. A nut G<SP>1</SP> on the head E engages a screw-threaded rod G which is mounted for rotation and axial movement on the column. For manual adjustment of the wheel, the rod G is rotated through gearing H, H<SP>1</SP>, H<SP>4</SP>, H<SP>5</SP>, by a handle H<SP>3</SP>. To provide the automatic step-by-step feed of the wheel, the lower end of the rod G is mounted by roller bearings J<SP>1</SP>, Fig. 4, in a member J adapted to be reciprocated vertically from a horizontal shaft L through a rod K' journalled on the cranked part L<SP>1</SP> of the shaft and connected by a pin K with the member J. Rotation of the shaft is effected by the pinion.N of the shaft engaging the rack N' which has, on opposite ends, pistons N<SP>2</SP>, N<SP>3</SP>, Fig. 9, working in the hydraulic cylinders O, 0'. These cylinders are arranged in an hydraulic circuit, comprising a pump R<SP>1</SP> for propelling fluid from a tank R through a relief valve R<SP>3</SP> to a conduit Shaving branches S', S<SP>2</SP> leading, respectively, to the cylinder 0<SP>1</SP> and, via an electro-magnetic valve T', to the metering device U. This device consists of a piston U<SP>2</SP>, Fig. 6, movable in a cylinder U' to the extent permitted by an adjustable stop U<SP>3</SP>. Initially, fluid pressure in both cylinders O, O<SP>1</SP> acts upon the pistons N<SP>2</SP>, N<SP>3</SP>, a spring controlled check valve V is so positioned that there is no escape of fluid from the cylinder O, and an electro-magnetic valve T is set so that the cylinder O<SP>1</SP> is in communication with the fluid supply through the conduit S<SP>1</SP>. With the position of the valve T unchanged, operation of the valve T<SP>1</SP> connects the supply conduit S<SP>2</SP> with a conduit S<SP>8</SP> so as to position the valve V for the passage of fluid from the cylinder O, through the conduit S<SP>a</SP>, to the metering device U. The operation of the valve T<SP>1</SP> also connects the cylinder C<SP>1</SP> to exhaust through the conduits S<SP>b</SP>, S<SP>5</SP> so that the piston U<SP>2</SP> is moved to permit the desired metering action, and the corresponding movement of the pistons N<SP>2</SP>, N' actuates the pinion N and shafts L, G. Successive metering actions cause step-by-step feed of the wheel D into the work, and the eccentric L<SP>1</SP> may be so positioned that these steps are of progressively decreasing extent. Restoration of the valve T' to initial position closes the valve V and the piston U' returns to its position against the stop U<SP>3</SP>. The carriage C carries dogs X, X' for operating a reversing hydraulic valve 10 controlling the movement of the carriage, and the valve T' is arranged to be operated momentarily at each end of the reciprocating movement of the carriage by a pair of switches W, W<SP>1</SP> mounted on the bed for coaction with dogs X<SP>2</SP>, X' on the carriage. The valve T for retracting the mechanism to normal position at the end of the full feed movement of the wheel is primarily controlled by a tripper P on the shaft L coacting at the desired time with a limit switch W<SP>2</SP>. Closure of this switch energises a solenoid to withdraw the dog X, with the result that the carriage moves for an additional distance until a second dog X<SP>5</SP> on the carriage actuates the reversing valve 10. Reversal of the carriage is, however, temporarily delayed in order to stop it for a period by the prior action of the dog X' upon a switch W<SP>4</SP>, and before the carriage is stopped this dog actuates a switch W<SP>9</SP> to start operation of indexing mechanism 11 for bringing the next pair of gear teeth into registration. Before indexing is complete, a switch 12 on this mechanism energises the valve T, thereby connecting the cylinder O with the pressure line through the conduit S<SP>6</SP> and the cylinder O<SP>1</SP> with exhaust; the rack is thus moved in the reverse direction to bring the shafts L, G to their original position. A further switch W<SP>3</SP> is then actuated by a second tripper P<SP>1</SP> adjustably mounted on the shaft L so as to de-energise the valve T. The stop U<SP>3</SP> of the metering device is screwthreaded in a cap U' of the cylinder U' in order to permit its adjustment and therefore vary the volume of liquid metered at each operation of the valve T<SP>1</SP>. This adjustment may be effected manually or automatically by mechanism driven from the shaft L.