Patent GB-643713-A (GB)
Title: Device for cutting and grinding gear wheels
IPC: B23F5/12
Filed: 1946-07-05
Abstract: 643,713. Gear-cutting. KONIKAL SOC. AR.L. July 5, 1946, No. 20212. [Class 83 (iii)] In a device for machining bevel or spur gears by means of a milling cutter or grinding wheel F having two straight operative edges, the cutting of the facing flanks of each tooth space is obtained by a transverse alternating movement of the work I relatively to the tool, each stroke of this movement comprising a stage of approach of either flank of the tooth space to either operative edge of the rod and a generating stage in which the flanks are machined along an involute profile, the approach and generating stages succeeding each other continuously and automatically when the work is given either manually or mechanically one transverse movement as the tool advances along the tooth space. For cutting bevel gears, the blank I is fixed on a shaft 1, Figs. 2 and 3, which is rotatably mounted in a sleeve 19 and carries a wormwheel 15 and a bevel gear 22. The sleeve 19 is in turn rotatably mounted in a sleeve 20 which is capable of being angularly adjusted in quadrants 18 cut in a supporting bracket 12 and is locked by nuts 21. The bevel wheel meshes with an arcuate rack 23 secured to supports 24, while the worm-wheel meshes with a worm 14 carried on a spindle 16 keyed to a dividing disc 17. A brake 11 acts on the bracket 12 which is pivoted on a pin 25 mounted on a base 3. The latter is movable along guides by a screw 27 in relation to a plate 9 pivoted on a pin 29 mounted on a plate 30 which carries a pin 31 to co-operate with two adjustable stops 10, 11<SP>1</SP> to limit the angular movement of the plate 9. The inclination of the plate 30 to a base 32 can be varied and the plate locked by a screw 34, the base 32 being fixed to the machine carriage by lugs 35. The tool F is a milling cutter or grinding wheel of trapezoidal section. In operation, the dividing device is adjusted to effect angular displacements of the blank according to the number of teeth to be cut, and the position of the pivot 25 relative to the pivot 29 is adjusted by the screw 27. The stops 10, 10<SP>1</SP> are then adjusted so that the angle of oscillation of the plate 9 corresponds to the angle of width of the tooth space and the brake 11 is adjusted to prevent free oscillation about the pin 25. Finally, the plate 30 is set to the desired inclination and locked so that the bottom of the tooth space to be cut is horizontal. The blank is now advanced towards the rod while the system is oscillated by a handle 26. Oscillation first takes place about the pin 25 until one of the stops 10, 10<SP>1</SP> strikes the pin 31, whereupon the resistance of the brake 11. is overcome and oscillation takes place about the pin 25 compelling the bevel wheel and the blank to rotate so that the tool machines a tooth flank. To cut spur gears, the device shown in Fig. 6 is used in which oscillations are replaced by reciprocations. In this device a plate 3 reciprocated by a crank and connecting rod mechanism is in frictional contact with a plate 9 and rotatably supports the blank I on an axle 16 in brackets 4. A disc 17, which has a radius equal to that of the pitch circle of the gear to be cut, is secured to the ends of two wires or flexible bands 6, 7, the other ends of which are secured at 8 to supports 18 integral with the plate 9. The latter has two teeth 10, 10<SP>1</SP> disposed one on either side of a fixed tooth 15. As the plates 3 and 9 are displaced to the right by the rotating crank, their position relative to each other does not alter until the tooth 10 engages the tooth 15. In this position, the tool is situated close to the upper extremity of the profile of one flank of a tooth space. The frictional resistance between the plates 3 and 9 is now overcome, causing the blank to roll so that one flank of a tooth space is machined. When the crank has passed the inner dead centre, the plates 3 and 9 travel to the left and the other flank of the tooth space is machined in a similar manner. A modification of this device is shown in Fig. 13 in which the movement of the crank mechanism is transmitted to the plate 3 through a lever 19 to which the connecting rod is attached at 20. The stops for the plate 9 in this modification consist of screws 23, 231 carried by parts 24, 241 to which are connected screws 25, 251 operated by a central screwed sleeve 26. Cams and servomotors may be used to actuate the device.