GB2198377A

GB2198377A - Shaft connection for torque transmission

Info

Publication number: GB2198377A
Application number: GB08727268A
Authority: GB
Inventors: Eric John Justice
Original assignee: Hardy Spicer Ltd
Current assignee: GKN Driveline Birmingham Ltd
Priority date: 1986-12-05
Filing date: 1987-11-20
Publication date: 1988-06-15
Also published as: GB8727268D0

Abstract

A method of making a torque transmitting connection between a shaft (10) and a sleeve (16, 17, 18), by swaging the sleeve into engagement with a portion of the shaft provided with e.g. splines (12), wherein the sleeve is deformed firstly (at 15) into engagement with a locating formation between sets of spines (12) on the shaft to determine the relative axial position of shaft and sleeve during the rest of the swaging process. The invention improves the positional accuracy of the connection between the shaft and the sleeve. The swaging is carried out by dies which impact radially on the sleeve. The shaft (10) may be the stub shaft of a motor vehicle constant velocity ratio universal joint. <IMAGE>

Description

SHAFT CONNECTION FOR TORQUE TRANSMISSION This invention relates to a method of making a connection for torque transmission between a shaft and a sleeve therearound, by providing the shaft with a portion, within the sleeve, which is non-circular in cross-sectional shape and deforming the sleeve in a swaging process to engage such portion of the shaft and thereby establish the torque transmitting connection.

The invention has been developed primarily in relation to the manufacture of drive shafts for use in motor vehicles. In manufacture of one type of drive shaft, a torque transmitting connection is required between a stub shaft provided on a member of a constant velocity ratio universal joint, and a tubular shaft element. Hitherto, such connection has generally been made by welding, e.g. friction welding. Establishing a torque transmitting connection by swaging an end portion of the tubular shaft onto the stub shaft of the universal joint, which may be splined to give it the required non-circular cross-section, has not been satisfactory because of lack of control of the overall length of the resulting shaft- universal joint assembly.

It will be appreciated that in the process of swaging a sleeve onto a shaft the deformation of the sleeve material causes an overall reduction in the diametral dimensions and thus a corresponding increase in the axial length dimensions of the swaged portion. For this reason the initial axial location of the sleeve relative to the shaft, achieved by first positioning and then retaining the sleeve and the shaft by gripping the free end of the sleeve and the shaft in work holding devices, cannot be maintained after the first contact between sleeve and shaft during the swaging process.

It will also be appreciated that the mechanical forces and vibration inherent in a rotary swaging operation will disturb the relative axial position of sleeve and shaft immediately before and at the point of first contact between the sleeve and shaft when the workholding device gripping the sleeve and the shaft is released. Thus the length of the finished shaft assembly cannot be controlled within the desired tolerance.

It is the object of the present invention to overcome this disadvantage of the swaging process as a method of connecting a shaft and sleeve.

Accordingly, the present invention provides â method of making a connection for torque transmission between a shaft and the sleeve therearound, by providing a shaft with a portion within the sleeve which is of non-circular cross-sectional shape and deforming the sleeve in a swaging process to engage such shaft portion to establish said connection, wherein the shaft is provided with a locating formation and the sleeve is caused during the swaging process initially to be deformed into engagement with said locating formation, to prevent relative axial movement, at said locating formation, between the shaft and sleeve during the remainder of the swaging process.

By causing the sleeve to engage the locating formation on the shaft at an initial stage of the swaging process, the problem above referred to, of the swaging process causing the shaft to move axially relative to the sleeve by an indeterminate distance, is overcome.

Although the swaged portion of the sleeve changes in length during the swaging process, its effect on the relative position of the shaft can be predicted and hence the finished assembly can conform to required dimensional tolerances.

Preferably the portion of the shaft is splined to give it the required non-circular cross-sectional shape, and the locating formation comprises a circumferentially extending groove or unsplined region in said splined portion.

The invention will now be described by way of example with reference to the accompanying drawings, of which:- Figure 1 is a section through part of a shaft and a sleeve therearound, prior to the carrying out of a swaging operation according to the invention; Figure 2 shows diagrammatically an initial stage of the swaging operation; Figure 3 is a diagrammatic partial end view on Figure 2; Figure 4 is a section through a finished connection according to the invention; Figure 5 shows diagrammatically a die for forming splines on the shaft.

Referring firstly to Figure 1 of the drawings, there is shown an end portion 10 of a shaft which may be a stub shaft connected to or formed integrally with a member of a constant velocity ratio universal joint. The shaft portion 10 fits within a sleeve 11 which may be the end portion of a tubular drive shaft. The shaft portion 10 has two regions 12 provided with circumferentially spaced axially extending splines, separated by an unsplined region 22.

A torque transmitting connection between the shaft portion 10 and sleeve 11 may be established by swaging the sleeve 11 into engagement with the shaft. This is carried out by a known process using a known rotary swaging machine, wherein dies disposed circumferentially about the sleeve 11 successively impact radially on the sleeve, to deform the latter. The result is that the overall diameter of the sleeve is reduced, and the material thereof is caused to flow into and between the splines on the shaft, to a form-fitting engagement.

Torque is thus effectively able to be transmitted and the connection is proof against axial disconnection under forces normally encountered in use.

During the swaging process, it will be appreciated that contact between the sleeve and shaft 10 may occur at virtually any point along the inter fitting portion thereof. When such contact is first established, no further axial relative movement between the shaft and sleeve is possible, but the shaft may move axially relative to the unswaged part of the sleeve to a greater or lesser extent, as the swaged portion of the sleeve elongates as its overall diameter is reduced. This axial movement of the shaft caused by elongation of the sleeve requires release of the workholding device holding the shaft in axial relationship to the sleeve. Once released, the mechanical forces and vibration inherent in the rotary swaging process causes positional accuracy between sleeve and shaft to be destroyed in random fashion.This cannot be accurately controlled by hitherto known swaging processes and thus the overall dimension of the sleeve shaft assembly when finished is subject to considerable variation.

According to the present invention, the sleeve is caused during the swaging process initially to be deformed into engagement with a locating formation on the shaft. Such formation conveniently comprises the circumferentially extending unsplined portion 22, which is effectively a circumferential groove, between the splined regions 12 on the shaft 10. The swaging dies, of which one is indicated at 13 in Figure 2 and parts of adjacent dies are seen in Figure 3, are provided with suitable projections as 14, which cause the sleeve 11 initially to be deformed inwardly in an annular band indicated at 15 in Figure 2. This engages in the unsplined region 22 between the splined regions 12 of the shaft 10, and thereby prevents relative axial movement between the shaft and sleeve at this point.

In the remainder of the swaging operation, although some axial movement will occur between the shaft and the unswaged part of the sleeve, the amount of such movement will be determined by the initial and finished dimensions of the sleeve, and will be substantially the same for successive shaft assemblies. Thus the problem of lack of dimensional control as above described is overcome.

Figure 4 shows a finished connection between the shaft and the sleeve. Portion 16 of the sleeve is reduced to the mean diameter in which it has close formfitting engagement with the splined regions 12, and this portion of the sleeve is joined by a tapered portion 17 to the unswaged portion 18 thereof. The portion 15 of the sleeve fits closely to the unsplined portion of the shaft 10. A further advantage of such fitting of the portion 15 is that if the swaged sleeve does not conform closely to the roots of the splines in regions 12, the portion 15 prevents any possible penetration of dirt and water to the interior of the tubular sleeve in use.

The splined regions 12 on the shaft 10 may be formed by a known rolling process using suitable dies moving tangentially of the shaft while force is applied thereto in the direction radially of the shaft. Figure 5 shows diagrammatically one such rolling die 1 , with spline-forming teeth 20. The die is intended to be moved tangentially of the shaft in the direction perpendicular to the plane of the drawing. A groove 21 in the die provides the unsplined portion 22 of the shaft 10 between the splined regions thereof.

Claims

1. A method of making a connection for torque transmission between a shaft and a sleeve therearound, by providing the shaft with a portion, within the sleeve, which is of non-circular cross-sectional shape and by deforming the sleeve in a swaging process to engage such shaft portion to establish said connection, characterised in that the shaft is provided with a locating formation and the sleeve is caused during the swaging process initially to be deformed into engagement with said locating formation, to prevent relative axial movement, at said locating formation, between the shaft and sleeve during the remainder of the swaging process.

2. A method according to Claim 1 wherein said shaft portion is splined.

3. A method according to Claim 2 wherein said locating formation comprises an annular unsplined region in said splined portion.

4. A method according to Claim 3 wherein the swaging is carried out by swaging dies having projections to cause said initial deformation of a portion of the sleeve.

5. A method substantially as hereinbefore described with reference to the accompanying drawings.

6. A drive shaft including a connection for eorque transmission, made by a method according to any one of the preceding claims.