Patent GB-902315-A (GB)
Title: Improvements in and relating to machines for the lapping of gear wheels
IPC: B23F23/00
Filed: 1960-09-07
Abstract: 902,315. Lapping gears. VERWALTUNGSGESELLSCHAFT DER WERKZEUGMASCHINENFABRIK OERLIKON. Sept. 7, 1960 [Sept. 11, 1959], No. 30809/60. Class 60. [Also in Group XXIX] A machine for lapping gears having intersecting axes, particularly spiral bevel or hypoid gears, has the relatively-movable wheel spindles so mounted that these movements comprise at least two synchronized components AO, OB, Fig. 1, each being independently adjustable as to length from, and angle at, the origin O of the rectangular co-ordinates V, H, the origin being a point of contact between a pair of gear teeth when the gears are in their correctly meshing position, the object being to cause the lapping contact to follow on the tooth flanks approximately the ideal spatial curve AOB in the co-ordinate system VOH; a modified " curve " is required for reversed operation of the gears; these are mounted on spindles 9 and 22, Fig. 4. The required movement components are effected by the use of two-part face cams 13, 14 and 15, 16, Figs. 5 and 9, for the vertical and horizontal components, respectively; a second group of similarly divided cams 52-55 is provided for reverse running. Sensing pins 19, 20 contact the selected pairs of cams to operate, through hydraulic follow-up units 28, 36, a horizontally slidable carriage 24 and the headstock 43 of the machine, Fig. 4, by means of the horizontal and vertical movement control-shafts 30 and 35, respectively. The cams are mounted in a carrier 51 which is reciprocated by a heartshaped cam 12 driven by a D.C. motor 49 which is provided with automatic speed control such that the rotational speed n 1  of the cam 12, during the traverse of cams 14, 16 across the sensing pins is changed to n 2  during the second half-revolution of the cam 12, so that AO (s 1 ), Fig. 1, is traversed in the same time interval as OB (s 2 ), or n 1 /n 2 =s 2 /s 1 . Each pair of face cams has a common meeting point about which each cam may be adjusted by micrometer means 111, 115, Fig. 8, to provide the required inclination of its face. Variations in the rotational speed of the cam 12 and angular adjustments of the face cams may be made to vary the lapping effect according to requirements. After adjustment all four cams in the same bore of the carrier 51 may be clamped together by a screw 123, Fig. 8. The sensing pin carrier 56 is movable in a direction normal to that of the cam-carrier 51 by a piston 127 slidable in a bore 128 of the camunit support 50 for selection of the cam group for forward or reverse running. The motor 49 drives through reduction gearing 48, Fig. 9, switch-operating cams 135, 136, mounted on the same shaft 134 as the heart-shaped cam 12. The cam 135 controls motor speed variations of the cam 12, as above described, through a relay 138 and potentiometers 146-149 in the motor field circuit and the cam 136, at each revolution of the shaft, closes the circuit of an impulseoperated time switch 153 whereby, after an adjustable time-interval, relays 154 and 156 are operated to move respectively the sensing pin carrier 51 and the reversing control switches of a 3-phase motor 157 which drives one of the gears to be lapped, the other running freely on the spindle 22. The horizontal and vertical follow-up units 28, 36 are identical. A control valve 66, Fig. 6, is slidable in a ported sleeve 79 within a piston 80 movable in a cylinder 81 which is carried by the carriage 24, Fig. 4, in the case of the vertical unit 36, or in the case of the unit 28, is secured to the machine base 23 to effect through a nut 31, Fig. 4, on the shaft 30 the movement of the carriage 24. Movement of the valve 66 admits pressure-fluid above or below the piston 80 via ducts 99, 98, the return flow from the opposite piston face passing through a central duct 100 in the valve-body to an outlet 104. The linkage through which the movements of the sensing pins 19, 20 are transmitted to the valve stems of the follow-up units 36 and 28, respectively, is shown in Fig. 5; back-lash in this linkage is taken up by the springs 83 interposed between the heads of the valves 66, 78 and the ends of their associated control shafts 35 and 30. These shafts are threaded to engage with nuts 44 and 31, Fig. 4, whereby the initial settings of the gear-carrying spindle 22 and carriage 24 may be effected by a squared end 42 and hand wheel 29 on shafts 35 and 30, respectively ; after checking against scale dials 41, 40 the shafts are locked to the headstock and carriage by levers 45 and 34.