Patent GB-649538-A (GB)
Title: Improvements in or relating to cutters for cutting curved tooth gear wheels
IPC: B23F21/22
Filed: 1947-10-29
Abstract: 649,538. Gear-cutting. VERWALTUNGSGES DER WERKZEUGMASCHINENFABRIK OERLIKON. Oct. 29, 1947, No. 28925. Convention date, Feb. 8, 1947. [A Specification was laid open to inspection under Sect. 91 of the Acts, May 3, 1948.] [Class 83 (iii)] A cutter for cutting curved tooth bevel gears by the continuous generating process comprises groups of blades, each group having at least one auxiliary blade and two finishing blades which travel through the same tooth space of the gear, and one finishing blade having an inner cutting edge acts on the convex tooth flank and the other finishing blade having an outer cutting edge acts on the concave tooth flank, the pitch points of the inner and outer cutting edges being at different radial distances from the axis of the rotation of the cutter in order to produce localized bearing in the teeth of the gear. As shown in Fig. 1, a slotting blade 33 and two finishing blades 29, 30 are fitted in slots in a disc 1 and the pitch points Ti, Ta of the finishing blades lie respectively inside and outside a circle a of the radius which the pitch points would have if full-meshing gears were to be produced. The blade slots have their axes tangential to a circle 35 centred on the cutter axis M and by interchanging the blades 29 and 30 gear teeth of a different curvature may be produced. Each blade has a slot for a securing screw 45 and' radial adjustment of the blades may be made by placing shims at the bottoms of the slots. Each group of blades may comprise six blades, as shown in Fig. 14, namely, a slotting blade 40 cutting along the bottom of the tooth space, a roughing blade 41 acting on both flanks of the tooth space, a trimming blade 60 for removing burrs at the top of one tooth flank, the finishing blade 29, a trimming blade 62 acting on the top of the other tooth flank and the other finishing blade 30. The trimming blades are of shorter axial length than the others so that they act only towards the end of the generating movement; the two trimming blades may be combined in a single blade. Two roughing blades such as 41 may be fitted, each working on one flank of the tooth space and various combinations of the roughing and finishing blades may be employed. A slotting blade having three cutting edges 361, 37 and 37', Fig. 4, may be employed.  The Specification as open to inspection under Sect. 91 also comprises a cutter having a series of blades mounted at an angle to the axis of rotation of the cutter and adjustable in the direction of their longitudinal axes so that, after resharpening, they can be adjusted again to their original cutting radius. A bladecarrying sleeve 4, Fig. 1 (Cancelled), is bolted to a tool head 3 and a conical insert 6 having inclined slots for blades 9 is held in the bore of the sleeve 4 by a bolt 7 engaging a base-plate 8. To adjust the blades, an adjusting member 11 is rotated by a pin 13 having teeth engaging external teeth on the member, and inclined surfaces 14 engaging corresponding surfaces on the plate 8 displace the member 11 axially. After adjustment, the blades are clamped by screw 18. In a modification, the member 11 has internal teeth engaging teeth on an adjustment pin fitted radially inwards of the blades. This subject-matter does not appear in the Specification as accepted.