Patent GB-1247870-A (GB)
Title: Machine for simultaneously performing machining operations on the centre bore and at least one end face of a rotatable workpiece
IPC: B24B33/00
Filed: 1968-09-30
Abstract: 1,247,870. Grinding. MICROMATIC HONE CORP. 30 Sept., 1968 [29 Jan., 1968], No. 46213/68. Heading B3D. A method of simultaneously generating a centre bore 481, Fig. 3, concentric to a characteristic circle, such as a pitch circle, and an end face 182 to centre bore squareness on a rotatable workpiece, such as a gear 15, comprises simultaneously rotating the workpiece in a centreless manner about an axis coaxial with the centre bore, machining the end face perpendicular to the axis, and machining the centre bore concentric to the characteristic circle. In a machine for carrying out the method, the teeth of the gear are also finished simultaneously with the machining of the centre bore and end face. Although, as described the workpiece is in the form of a gear, it may take the form of the race of a ball bearing. The machine consists of a frame 10, Fig. 1, having a workhead 12 for storing, loading, rotating and unloading workpieces. The workpiece 15, while it is rotated, has its centre bore honed by a reciprocating, non- rotating tool 13, Fig. 3, its upper and lower faces 182, 165 honed by upper and lower pairs of honing tools 324, 324a, 324b, 324d, and its teeth are machined by a driving machinery gear 16 and a braked machining gear 17, the gears 16, 17 rotating the gear workpiece 15 in a centreless manner. The workhead 12 has a storage shoot 18 for workpieces leading at its lower end to a control block 36, Fig. 1, having a bore to receive a workpiece. The block is rotatable from a position in which its bore is aligned with the shoot 18 to a position aligned with a workpieceload shoot 65 each time the head 55 carrying the tool 13 is lowered for a work cycle to feed a workpiece to the workhead. Alternatively, a push rod on an air cylinder device may retract the block. The workpiece fed by the shoot 65 is deposited on a plate 67, Fig. 6, adjacent a guide wall 107 along which it is moved by the leading end 122 of a pusher 121 movable by an air cylinder 135. As the workpiece moves along the wall 107 it is pressed by a resilient cantilever 118, formed by a pair of coil springs, into meshing engagement with the rotating drive gear 16 which moves the workpiece until it also meshes with the braked gear 17. When the workpiece is in the work position, it is positioned axially by abutment of its lower face with a rotatable but fixed roller against which it is urged by a roller 179 carried on an arm 171 and rocked about a pivot 178 by an air cylinder 190. In an alternative arrangement, the arm 171 cooperates with an air-sizing gauge which controls the reciprocation and expansion of the tools for honing the end faces of the workpiece. The gears 16, 17 are mounted on spindles 223, 226, Fig. 10, rotatably mounted in bearings on a baseplate 11. Each spindle carries a freely-rotating sprocket 249, 249a engaged by a chain 248 driven from an electric motor 244, Fig. 1. Each sprocket can be clutched to its associated shaft by a dog clutch 260, 260a having a part 257, 257a carried at opposite ends of a lever assembly 283 movable about a pivot 287 by a solenoid 293 so that one or other of the gears are driven by the chain drive 248. The spindle 226 can also be engaged by a brake 306 operated by an air cylinder 310. During loading and honing, the gear 16 is driven by the chain and the brake 306 actuated so that gear 17 acts to press the workpiece against gear 16. During unloading, the gear 16 is free to rotate and gear 12 is driven to push the workpiece along a guide wall 109, Fig. 6, to an ejector. The gears 16, 17 may be in the form of master gears and effect a cold working or burnishing action or may be of bonded abrasive material, cast iron or the like. The end faces of the workpiece are honed by the tools 324, 324a, 324b, 324c. Each tool and its mounting 318, 319, 320, 321, Fig. 1, is substantially identical. The tool 324 is mounted for sliding movement along a guide 327, 328, Fig. 17, and is moved to an outer, operative position when a plate 336 having an inclined guide 334 is moved by an air cylinder 340. The guides 327, 328 are carried by a block 325 mounted on a bracket 348, Fig. 13, which is reciprocated along a shaft 360 by rotation of a constant motion cam 422, similar cams driving the other tools so that all the tools reciprocate in synchronism as they are pressed by their air cylinders against the end faces of the workpiece. The cams are driven by a chain drive from an electric motor and are connected by an adjustable pivoted linkage 391 to the brackets. In an alternative arrangement, the brackets are reciprocated by an adjustable crank mechanism. The bore of the workpiece is honed by two abrading tools 471, 472, Figs. 23 and 24, located in slots 480 in the lower end 463 of a tool body 460. The tools can be extended into engagement with the bore of the workpiece 15, when the tool is moved to a lower, operation, position, by downward movement of blocks 483 having inclined surfaces 482 abutting the rear of the tools, the blades being connected by drivers 485, 485a to rods 488, 488a connected to pistons 495, 496 disposed in air cylinders 490, 490a in the tool body 460. Air sizing jets 497, 499 are disposed adjacent the tools for measuring the size of the bore in the workpiece. The tool body 460 is free to float laterally on an adaptor 461, but is held against rotation relative to the adaptor, connected to a spindle 462 which, during honing, is reciprocated in the spindle head 55, Fig. 1, by a linkage 558 oscillated about a pivot 561 on the head by an arm 573 vertically reciprocated by a constant motion cam mounted on the head and rotated by a chain driven from an electric motor. When a workpiece is in engagement with the gears 16, 17, the spindle head 55 is lowered along vertical guides 26, 27 by an air cylinder 525 to position the tool within the bore of the workpiece. The tool is then vertically reciprocated by movement of the spindle 462 relative to the head by the cam drive as the tools 471, 472 are urged by the pistons 495, 496 and blades 483 first at a high pressure and then at a low pressure into engagement with the bore of the workpiece. The operation of the machine is controlled automatically by electric and pneumatic circuits. Coolant is supplied to the workpiece through a nozzle 610, Fig. 1.