Patent GB-322319-A (GB)
Title: Improvements relating to machines for grinding the teeth of gear wheels and for other like purposes
IPC: B24B53/08
Filed: 1928-11-17
Abstract: 322,319. Gear Grinding Co., Ltd., and Snarry, J. W. Nov. 17, 1928. Turning.-A machine for grinding toothed gears and for like purposes, such as grinding splines on shafts, is provided with automatic means for trueing the profiled grinding-wheel g comprising diamond tools b acting on the side faces f of the wheel and a peripheral diamond tool l located diametrically opposite the side trimmers. The profile imparted by the side trimmers is determined by templets e acting through pantograph mechanism d on the tool holders c. The grinding- wheel, driven by an electric motor i, is mounted in a headstock k carried by a horizontally reciprocating slide h which is moved back to position the grinding-wheel against the trueing mechanism when required. The headstock also carries the peripheral trimmer l which is mounted in a holder m rotatable about an axis 1, 2, located slightly below the tool point. The holder m is in turn mounted in a carrier n which can oscillate about an axis 3, 4 in a bracket o pivoted to the headstock and rotatable about an axis 5, 6. The holder m carries a uinion p engaging a quadrant q which is movable on a fixed spindle q<1> and is actuated by a rod r and crank disc s, driven through worm reduction gearing 3, clutch 2, and flexible shaft 4<1> from the motor i. The angular movements of the carrier n are limited by abutments t and the rod r is connected to the quadrant q by spring mechanism. Thus when the rod r is actuated, the carrier n first swings about the axis 3, 4 to move the trimmer l over part of the peripheral face of the wheel. When the arm n is arrested by its stop the continued movement of the rod r causes the quadrant q to rotate the pinion p against a spring and so oscillate the trimmer about the axis 1, 2 to round off one edge of the wheel. At the end of the return movement of the rod r the opposite edge of the grinding wheel is rounded off. After a predetermined number of trimming operations the grinding wheel is fed downwards towards the side trimmers and in order also to feed the peripheral trimmer towards the wheel, a lever x secured to the bracket o is held by a spring against an adjustable stop y on the stationary headstock slide. The distances from the axis 5, 6 to the stop y and the tool point l are equal so that as the headstock is fed downwards, twice this movement is imparted to the tool l which is thus advanced to the wheel by the same amount as the wheel is advanced to the side tools. The automatic feed of the wheel towards the side trimmers is effected by a hydraulic piston 6 controlled by a valve 7 actuated by a piston a operating the side trimmers. The piston 6, Fig. 13, is connected through lever 9, two part rod 10, 10<1>, lever 11, spring plunger 13, and ratchet mechanism 38, 39 to the vertical feed screw. The rod portion 10<1> is arranged to be positioned to coact with the portion 10 only when the slide h is withdrawn for trueing operations. The rod 10<1> also carries a tappet 8 which acts through lever mechanism to operate the clutch 2 controlling the peripheral trimming operation. To start the trimming operations automatically an abutment 18 on the slide h is arranged to operate a plunger 20, Fig. 4, to shift a pawl 21 and valve stem 22 to admit fluid to the cylinder 24 of the side trimmers. This also withdraws a projection 26 from a cam 25 which then makes a single revolution while the trimming operations are performed. The cam shaft 31 is connected by gearing, Fig. 13, to the distributing valve 7 which controls the feed piston 6 and the cam shaft also carries a ratchet wheel 32 which is actuated by pawls 33 connected to the rod 34 which transmits motion from the piston a to the pantograph of the side trimming mechanism. The movement imparted by the pawls 33 to the valve 7 through this gearing is sufficient to rotate the valve from one position to another to produce opposite movements of the feed piston 6. When the cam 6 has completed a revolution the valve stem 22 is returned by a spring and when the slide h moves away from the pawl 21 is reengaged in readiness for a fresh cycle of operations. The fluid admission to opposite sides of the cylinder a may be controlled by a slide valve 37 actuated through lever mechanism from the piston rod 34. Pressure fluid is derived from a pump 41, Fig. 13, which communicates with the valve 7 and also, through a pressure regulator 42, with the valve 22.