Patent GB-513329-A (GB)
Title: Improvements in the process of, and apparatus for, producing bevel gear wheels
IPC: B23F5/02
Filed: 1938-04-04
Abstract: 513,329. Grinding toothed gears. KLINGELNBERG, G. A., KLINGELNBERG, W. H., and KLINGELNBERG, H. W., [trading as KLINGELNBERG SOHNE, W. F.]. April 4, 1938, No. 10284. Convention date, April 3, 1937. [Class 60] [Also in Group XXII] In a process for grinding straight-toothed bevel gears having convex tooth flanks, the teeth are formed by a grinding wheel of conjugate crown wheel form which cuts out a blank without pre-shaping of the teeth and is rocked transversely during its feed movement along the teeth. The blank 1 is mounted on the spindle 2 of a dividing head 3 carried by a quadrant 4 which may be angularly adjusted to set the blank about an axis 5 passing through the blank pitch-cone apex. The quadrant is supported in a cradle 6 which is carried on rollers 8 and swings in a trunnion bearing about the horizontal axis of a basic crown wheel engaging the blank and represented by a grinding-wheel 23. The cradle is mounted on another' angularly adjustable slide 9 carried by a slidable table 10, and rocked by means of a hydraulic cylinder 11 actuating a rack engaging a sector on the cradle. In order to rotate the blank in unison with the crown wheel or cradle movement a stationary wheel 14 coaxial with the cradle is connected by a flexible band passing from an adjusting device round pulleys 18 to a wheel 15 on a drum 16 of the dividing head. For indexing the blank the drum 16 carries alternately acting pawls 19, 19' coacting with a wheel 20 on the work spindle. The pawls are controlled by hydraulic pistons 21, 21<1>, and in the position shown in Fig. 4 the pawl 19 is engaged and pawl 10<1> disengaged. The blank spindle is under constant torque from an hydraulic motor 22 which maintains the tension of the band mechanism. At the end of a generating roll when the tool is out of contact with the work the pistons 21, 21', are shifted to disengage the pawl 19 and engage the pawl 19<1> and owing to the torque of motor 22 this change over of the pawl is accompanied by movement of the index wheel and work spindle through one tooth space. The grinding wheel which is of rack - tooth profile is reciprocated along the tooth space and is arranged to cut one flank 25, Fig. 13, of a space in one direction of movement, the opposite flank 26 being cut on the return movement by the opposite face of the wheel which is shifted through a distance equal to the pitch line thickness at the point of reversal so that the direction of movement of its operative face always lies in a plane containing the blank and crown wheel axes. If skew teeth are to be cut the grinding wheel is set over at the required angle. For operating in this way the dividing wheel has twice as many teeth as the blank so that the right and left tooth flanks are brought into cutting position alternately. The grinding wheel is also given an adjustable swinging movement during its passage along a tooth in order to produce a crowned tooth form, Fig. 17. For this purpose the wheel is carried in a housing 27 and is driven by a motor 28. The wheel may be axially adjusted by a hand wheel 32 and the pitch thickness movement referred to above is effected by a hydraulic cylinder 34. The housing 27 has extensions 35, 36 which are guided in bearings 37, 38 the former of which constitutes a hydraulically operable piston for effecting the cutting traverse. In a modification the member 35 is grooved to receive a cam driven by a motor to traverse the grinding wheel. During the traversing movement a roller 42 on the housing may engage a stationary templet cam 41 to rock the grinding wheel about the axis of bearings 37, 38, to produce the crowning of the teeth. When the stationary cam is employed for cutting a crowned tooth form the teeth must all be cut on one side and then another cam used for cutting the other side of the teeth, but for cutting in the manner shown in Fig. 13 a rotatable templet cam 43, Fig. 12, is employed. This cam is rotated at the ends of the wheel traverse by means of a rack 46 operated by a cylinder 45. The same cam may be used to give the lateral movement of the grinding wheel between the forward and return strokes, Fig. 13, the profile of the wheel being modified if necessary to compensate for the tilt of the wheel produced by the cam. In one form there is a slow generating movement and rapid reciprocation of the wheel but if desired the generating roll may be rapid and the tool movement slow. the indexing mechanism being actuated by stops on the grinding head. For hydraulic actuation a pump 49 delivers to a main 50 supplying the valves A, B. C, of cylinder 11, indexing head 3. and cylinders 34, 35. A trueing device for the wheel comprises a peripheral tool 53 and levers 52 carrying tools for dressing the flanks, the levers being set to the required angle by pointers 55, and being moved across the flanks by a motor 55 acting through arms 56 and levers 58. One of the levers operates a ratchet wheel 61 geared to a screw which gives an automatic feed to the grinding wheel carriage 63. A further lever from the wheel 61 imparts a feed movement to the peripheral tool 53 which is equal to twice the feed of the slide 63 so that the effective section of the grinding wheel remains in the same position.