Patent GB-656650-A (GB)
Title: Improvements in or relating to machines for cutting bevel gears
IPC: B23F9/10
Filed: 1948-04-08
Abstract: 656,650. Gear-cutting. VERWALTUNGSGES. DER WERKZEUGMASCHINEN. FABRIK OERLIKON. April 8, 1948, No. 9883. Convention date, April 11, 1947. [Class 83 (iii)] In a machine for cutting bevel gears, including a headstock 1 for the gear blank a and a generating unit 6 for the tool b, the tool carrier 3 being disposed in a cross slide 4 which is carried by a generating drum S rotatably mounted in the unit 6 which is movable horizontally on the machine bed 7, and including a pressure fluid control system, a single operating lever 9 is coupled with a main control valve 29 for the pressure fluid, the lever being operative to control the main drive of the machine, the advance and return movement of the tool towards and away from the fixed gear blank in the direction of the axis of the imaginary crown-wheel of the gear to be cut, and the feed or generating gear of the machine. The headstock is carried by a table 2 angularly adjustable in a horizontal plane by means of hand wheels H1, H2. The lever 9 can be moved by hand to a number of positions to impart successive rotative steps to the control valve 29, operatively connected to a pump 39, so as first to cause the valve to chuck the blank, release a brake 37 and effect engagement of the clutch 36 of the main drive of the motor, then to effect the advance of the tool towards the gear blank, and finally to effect engagement of the generating gear. The tool is advanced towards the gear blank by displacing the generating unit 6, which is secured to a piston 28, relatively to the machine bed 7 until it engages an adjustable abutment 73 when a piston 38 is operated to actuate an electric switch EL in the circuit of an electric motor driving a cooling agent pump so that when a pre-selector switch 66<SP>1</SP>, Fig. 1, is actuated to close the circuit, a jet of cooling liquid is delivered against the tool. When the lever 9 is moved to the position in which the lower end of a lever 79 abuts a shut-down piston 32, a clutch 31 is operated to cause rotation of the drum 5. The latter is provided with three adjustable abutments 17, 18, 19 co-operating successively with a star-shaped cam 20 secured to the axis of an auxiliary control valve 21, disposed in the unit 6 and operatively connected to the pump 39, to impart three successive rotative steps to the valve when the drum 5 effects the rolling or generating feed movement, the first of these steps having no control function, while the second step of the valve results, through the movement of a piston 14, in an increase of speed of the drum 5 after the tool has cut the bottom of the tooth space, and the third step of the valve initiates the return of the lever 9 to a position in which the clutch 36 of the main driving motor is disengaged and a switch E actuated to start a rapid feed motor so as to effect the return rolling movement of the drum 5 at increased speed during which return movement, the abutments 17, 18, 19 impart three steps in reversed direction to the valve 21, the first two of these reverse steps having no control function, while the third step causes the rapid speed motor to be switched off. The rate of increase of the generating speed is adjustable by adjusting the position of a stop 88 relative to a stop 90 on the piston 14. When the blank is subjected to a finishing cut, the generating speed can be increased from the beginning of the out so that no other increase of generating rolling movement is required. The bevel gear can be cut with spiral teeth in which case the valve 21 is so arranged to co-operate with the abutments on the drum 5 that the generating movement of the tool can be effected in both directions of rotation of the drum. Specification 35367/47 is referred to. Chucks.-The chuck 61 for the gear blank is clamped and released by a piston 41 to which pressure fluid from the control system is supplied through a valve 42, the arrangement being such that the lever 9 can be brought to the position corresponding to engagement of the main drive only when the chuck is under clamping pressure by the pressure fluid. The conduit 104 supplying pressure fluid to the piston 41 for releasing the chuck is 'connected with the shut-down piston 32 which is adapted to actuate the lever 9 so that when the chuck is released, the lever 9 is moved to a position to disengage the main drive of the machine. Clamping slides.-When the generating unit 6 engages the abutment 73, a piston valve 25 is operated to supply pressure fluid to clamping devices K6 and K8 for locking the unit 6 to the bed 7 and an overhead tie 8 to the unit 6.