Patent GB-269607-A (GB)
Title: Improvements relating to metal cutting and grinding machines
IPC: B23F1/02
Filed: 1926-08-12
Abstract: 269,607. Gear Grinding Co., Ltd., and Snarry, J. W. Aug. 12, 1926. Gear-cutting.-A metal cutting or grinding, machine such as a gear grinding machine, of the kind having a reciprocating slide and mechanism for indexing the work is provided with automaticallycontrolled hydraulic rams which are supplied wich fluid from a valve under escapement control for actuating the slide at different forward and return speeds and for operating the indexing mechanism. In Fig. 1 the slide d carries a profiled grinding-wheel c which is preferably driven from an electric motor and is reciprocated past one or more blanks a mounted on a spindle carried in a dividing head b. The latter comprises a wheel h actuated by a pawl i which is moved intermittently by means of an hydraulic cylinder p through the rack n, pinion m, crank k, connecting- rod l, and slide j. The main slide is reciprocated by a hydraulic ram e, the piston g of which has a larger area exposed tc fluid on its front face so that the working stroke is made at a slow speed, and the return at high speed. A by-pass 15 having a valve 16 may be employed tc vary the speed of the forward stroke. In normal working the slide is reciprocated so that the grinding wheel just clears the blanks at the end of its return stroke but the slide is periodically withdrawn to the position shown in Fig. 1, and the wheel is then trimmed by diamond tools r on spindles s which are oscillated by mechanism from a piston t in a hydraulic cylinder v. The fluid is supplied from a tank x by a pump y and the delivery to the cylinders #, p is controlled by a rotary valve which is driven intermittently by a motor 9 under the control of an escapement 10. The valve comprises a portion 7 controlling the cylinder # and a portion 8 controlling the cylinder p. In the position shown in Fig. 1, fluid is admitted to the rear of the piston g through the pipe 14 and exhaust from the cylinder f passes through pipes 37, 13. After a quarter-turn of the valves 7, 8, fluid passes to the cylinder p along the pipe 11 and is exhausted through pipes 12, 13. After the next quarter-turn fluid flow to and from the cylinder p is reversed and after another quarter-turn the ram e makes the working stroke while the ram o remains stationary. The construction of the valve and its driving motor is shown in Figs. 9 and 12, the portions 7 and 8 being contained in a single body member 24. The lower end of the valve casing contains the cylinders 26 having plungers 27 which actuate a crank 28. The admission of fluid to each cylinder in turn is controlled by ports 29 co-operating with distribution passages 30 in the casing. The cylinders all exhaust into the passage 13. The tendency of the valve to be constantly rotated is resisted by the escapement 10 having a groove engaged by pins 14 on levers 42 which are actuated respectively by the main slide and by the dividing mechanism. The formation of the disc and the arrangement of the pegs is such that the disc is arrested after each quarter revolution. One of the pegs is actuated by tappets 43 on the main slide through a swinging lever 31 and rod 33 while the other peg is similarly actuated by a cam disc on the dividing-spindle through a forked lever 34 and link 33. When it is required to withdraw the slide d fully for the trimming of the grinding- wheel a projection on the lever 31 is swung away from the tappet 43 thus allowing the ram to continue its motion until the piston reaches the end of the cylinder, this movement being cushioned by the partial closing of the valve 4 by a tappet 47 engaging a lever 5. The trimming-mechanism is actuated by fluid which passes through a handcontrolled valve 17 and automatic valve 18 to the cylinder v. The valve 18 is operated to reverse the movement by tappets 19 which act through a lever 20 working in conjunction with a changeover spring 23. The valve 4 may be operated from the lever 5 to return the fluid from the pump to the tank along the pipe 2. In the machine embodiment shown in Fig. 2 the dividing mechanism, which is preferably of the form described in Specification 244,647, is actuated from a vertical spindle 36 and the trimming-mechanism is mounted in a casing. The valve 17 is designed to permit two speeds of operation for the trimming-mechanism. The invention may be applied to other machines such as milling and shaping machines. Specification 269,611, [Class 60, Grinding or abrading &c.], also is referred to.