US2404573A - Gear grinding machine - Google Patents

Description

M 23, 1946.. w GRfAF 2,40%,573

I I GEAR GRINDING MACHINE I I Filed March 20, 1944 3 Sheets-Shae: l

July 23, 1946. w, GRAF 2,404,573

GEAR GRINDING MACHINE Filed March 20, 1944 3 Sheets-Sheet 2 Jul 23, mm w. GRAF mm m- GEAR GRINDING MACHINE Filed. March 20, 1944 3 Sheets-Sheet a Patented July 23, 1946 GEAR GRINDING MACHINE Willi Graf, Zurich, Switzerlaniassighor to Maag- Zahnrader und -Maschinen Aktiengesellschaft,

Zurich, Switzerland Application March 20, 1944', Serial No. 527,270 In Switzerland Jan. 25, 1943 4 Claims.

This invention relates to gear grinding machines operating by means of relative rolling motion of involute form.

Owing to the continuously growing tendency to increase the stressing of hardened ground gears and the resulting elastic deformations of cooperating gear teeth, Wherefrom flattening and permanent deflecting ensues, it becomes necessary to give a form to the tooth flanks deviating from the true involute.

Devices serving this purpose are already known. One type of such devices consists in that the rolling are which for producing the rolling motion rolls on stretched tapes is given at certain points of its circumference a form which deviates from the circular form. This results in a corresponding alteration of the rolling motion, due to which, for example, the face of the tooth is flattened to some extent compared with the theoretical involute form so that the teeth enter into mutual engagement free from shocks.

In the gear grinding machine according to the present invention the same purpose is intended to be served in a more precise and effective manner in that between the rolling elements and the work carrier a device including a diverting member is intercalated which member is temporarily deflected, while the rolling motion progresses, the

extent of deflection being transmitted to the Work carrier, whereby the work has imparted thereto corresponding movement in addition to said normal rolling movement.

Advantageously, the diverting member is arranged for cooperation with cam means which, for the purpose of being adaptable to the extent of deflection required, are exchangeable and adjustable relative to the diverting means.

Two embodiments of the invention are illustrated, by way of example only, in the accompanying drawings, in which Fig. 1 shows an elevation of a gear grinding machine;

Fig. 2 shows an end elevation thereof;

Fig. 3 is a partial View of Fig. 2 on a larger scale;

Fig. 4 is a longitudinal section of the dividing device of the machine;

Fig. 5 shows a cross section on the line V-V in Fig. 4;

Fig. 6 shows a cross section on the line VI-VI tooth gaps of the dividing disc ll.

Fig. 11 shows a cross section on the line XI-XI in Fig. 10.

On the bed 5 of the machine shown in Figs. 1 to 6 a slide 2 is arranged for movement parallel with the longitudinal axis of the machine. The drive of the slide 2 is derived, in a known manner, from a motor 39 via a gear wheel transmission gearing 4t and a screw spindle M, A second slide 3 is mounted on the slide 2 for movement perpendicularly to the longitudinal axis of the machine. The drive of this slide is also derived from the motor 39 via a belt 42 and a crank pin 43. Between the centering points of the slide 3 a mandrel 4 is clamped for carrying the work 5. The compound movement of the work 5 carries it in a definite path relative to grinding wheels 29 which are mounted on a fixed part of the machine frame and are rotationally driven by electric motors 29.

Further, the slide 3 includes a shaft 6 (Fig. 4) on one end of which a rolling arc I is mounted which is connected by means of .tensioned steel tapes 8 (Figs. 2 and 5) with two holders 9 which are screwed to the slide 2. In the shaft 6 is rotatably mounted a further shaft l0 which carries a dividing disc H as well as one of the centering points between which the work supporting mandrel 4 is clamped. The other end of the shaft 6 is firmly connected to a casing i2. In the latter a plug i3 is mounted which is eccentrically arranged relative to its axis and houses a shaft 14. On this shaft two lever arms are secured.

One of said lever arms which is designated by l5 carries a bolt l6 which engages into the The other lever arm I! serves for disengaging the bolt l6 from the dividing disc H and engaging it with the latter again in the manner of a pawl in the course of the dividing operation. This bolt control is. efiected by means of an eccentric l8 on which rests the outer end of the lever arm I l and which is temporarily turned by the dividing shaft 2] via a pair of bevel wheels 19, 20. A spring 22 exerts tension on the lever arm ll, thereby urging the bolt I6 against the dividing disc H.

For realizing the modifying of the tooth-profile striven at, a diverting member in form of a lever arm 23 carrying on its outer end a guide roller 24 is firmly keyed to the plug Hi. This roller slides on a guide segment 25, which is firmly I screwed to a ring 21, by pressure action exerted on the roller by means of a spring 38. Thisring is rotatably mounted in a fixed holder 28 which in turn is mounted on the slide 3. At both ends of the guide segment 25 cam pieces 26 are arintense flattening of the tooth face.

ranged. These are so disposed that the guide roller 24 and thus the diverting member 23 together with it has diverting movements imparted thereto at certain points of the rolling path of the work 5. By this means the eccentrically mounted shaft 14 effects small turning movements about the axis ofthe plug 13, thereby imparting additional rotation to the bolt [6 which rotation alters the normal rolling motion so as to result in a form of the tooth profiles ground by the grinding disc 29 modified from the true involute.

In Figs. 7, 8 and 9 three tooth-profiles'of modified form of the tooth face are shown. Fig. 7 illustrates a modified form representing an average of alteration. Fig. 6 illustrates a modified v form of less alteration but extending up to the pitch circle, whereas Fig. 9 illustrates a short but These various forms of modified profile are effected by accordingly shaping and positioning the two cam pieces 26. To this end thesegment 25 canbe displaced relative to the holder 28 by turning the ring 21, whilst the cam pieces 26 can be firmly screwed to the segment 25 in different positions. Furthermore, the cam pieces 26 can be exchanged for other such pieces with greater or smaller diverting curvature by which means in the end any desired profile modification of the kind shown in Figs 7 to 9 can'be obtained.

A further embodiment of the invention is shown in Figs. 10 and 11. In this arrangement the effecting of the modifying movement in addition to the rolling movement is carried out directly in conjunction with th operation of the rolling elements by relative rotation of the shaft 6 to the rolling are on which shaft th said are is loosely mounted. For this purpose a sleeve 30 is keyed to the shaft 6. In the rolling are I a pin 3| is arranged about which swings a lever 32 constituting the diverting member. This lever carries at one end a bolt 33 which engages into an arm 34 on the sleeve 3i! and at the other end a guide roller 35 which, also in this arrangement, slides in the course of the rolling movement along cam pieces 36 so as to be displaced by the diverting curvatures of said pieces. The movement of the bolt 33, that is, the sleeve 30 resultsin the desir d additional movement of the work to the normal rolling movement. A spring 31 holds the guide roller 35 continually into bearing engagement with the cam pieces 36. The latter are connected to the slide 3 directly as shown in Figs. and 11. Alternatively, said pieces may be threadedly connected with'a ring in adjustable manner which is rotatably mounted in a holder which is secured to the slide 3.

I claim:

1. Ina gear grinding machine for producing the tooth-profile on the work by means of relative rolling motion between the work and the grinding tool, a rotatable grinding tool, a work carrier, work carrier drive elements, means for generating a normal involute motion relative to the tool and applying said motion to said work carrier drive elements, and a motion-altering mechanism interposed between said drive elements and said involute motion generating means for modifying the involute motion applied to said work carrier to compensate for elastic deformation of the gear under heavy load in service.

2. In a gear grinding machine for producing the tooth-profile on the work by means of relative rolling motion between the work and the grinding tool, a rotatable grinding tool, a work carrier, work carrier drive elements, means for generating a normal involutemotion relative to the tool and applying said motion to said work carrier drive elements, a motion-altering mechanism interposed between said drive elements and said involute motion generating means for modifying the involut motion applied to said work carrier to compensate for elastic deformation of the gear under heavy load in service, said motionaltering mechanism including a removable and replaceable cam, and means for adjusting said cam, the conformation of the cam conforming to the variable requirements depending on the deformation of the gear in use.

3. In a gear grinding machine for producing the tooth-profile on the work by means of relative rolling motion between the work and the grinding tool, a rotatabl grinding tool, a work carrier, work carrier drive elements, means for generating a normal involute motion relative to the tool and applying said motion to said work carrier drive lements, said involute generating means including a dividing device having a dividing disc, a motion-altering mechanism interposed in said drive elements and said involute motion generating means for modifying the involute motion applied to said Work carrier to compensate for elastic deformation of the gear under heavy load in service, a removable and exchangeable cam included in said motion-altering mechanism, and means for adjusting the cam to adjust the'alteration from the involut in accordance with the deformation expected in the gear in use.

4. In a gear grinding machine for producing the tooth-profile on the work by means of relative rolling motion between the work and the grinding tool, a rotatable carrier for said work, elements including a rolling are for effecting normal involute generating rolling motion on each other along a stretch of travel in accordance with the length of profile to be ground and imparting said motion to said-rotatable work carrier, a rolling motion diverting device intercalatedbetween said work carrier and said elements for temporarily modifying said normal rolling motion, a dividing device being carried by a machine shaft, and a diverting member associated'with said diverting device and mounted on said rolling are for trans-' mitting the modifying movements of said diverting device to said Work carrier, thereby correspondingly altering said normal rolling motion of said carrier. I WILLI GRAF. 1

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