GB2309502A

GB2309502A - Securing member on shaft

Info

Publication number: GB2309502A
Application number: GB9601375A
Authority: GB
Inventors: Stephen Terence Rickels
Original assignee: Sturmey Archer Ltd
Current assignee: Sturmey Archer Ltd
Priority date: 1996-01-24
Filing date: 1996-01-24
Publication date: 1997-07-30
Also published as: GB9601375D0

Abstract

In an assembly comprising a sunwheel 4 and a shaft 2 a wing 1 is formed on the shaft 2 by opposing tools (7,8, Figs 3a,b,c,) which displace material from the shaft to stand proud of the normal circular cross section of the shaft. More than one wing may be formed as desired. A slot 5 is machined into the sunwheel 4 and when the sunwheel is inserted over the shaft 2 the wing enters the slot 5 to lock the sunwheel 4 and shaft 2 together to prevent relative rotation thereof. This arrangement avoids weakening of the shaft by drilling and pinning which is the conventional method.

Description

A SHAFT ASSEMBLY AND RELATED METHOD The present invention relates to a method of locking a rotational member such as a gearwheel on a shaft and to a member shaft combination.

The method is particularly, but not exclusively applicable to the locking of a sunwheel on the shaft of an epicyclic change speed gear system. At the present time this locking is achieved by drilling a bore through the sunwheel and the shaft and inserting a pin through the bore.

The drilling of both sunwheel and shaft can weaken sunwheel and/or shaft and this may lead to failure.

According to one aspect of the present invention there is provided a shaft and member assembly in which relative rotational movement of the member and shaft is prevented by coacting formations on the member and shaft, the formations on the shaft being formed by displacing shaft material.

According to another aspect of the present invention there is provided a method of locking a rotational member on a supporting shaft including the steps of displacing material from the shaft to form one or more formations, forming complementary formations in the member and introducing the member onto the shaft so that the formations on the shaft coact with the complementary formations on the member to prevent relative rotational movement.

In a preferred embodiment of the invention, the shaft is an axle of a gear system, preferably an epicyclic gear system, and the member is a sunwheel of that system mounted on the axle. The formations comprise wings which are formed by displacing material from the normal circular envelope of the axle cross section. These wings then stand proud of this normal envelope. When the sunwheel is inserted over the shaft axially extending slots in the sunwheel receive these wings to prevent relative rotational movement as aforesaid. One or more wings and corresponding number of slots may be provided as desired The slots may extend all the way through the material of the sunwheel from the inside to the outside or they may be formed as keyways internally of the sunwheel. The material to form the wings is displaced by opposing tools which are pressed into the axle from opposite sides.One pair of tools is normally provided for each wing to be formed so that wings may be formed simultaneously where more than one wing is provided. The tools may be circular in cross-section, or any other suitable cross-section. The slots in the sunwheel are machined.

In order that the invention may be more clearly understood embodiments thereof will now be described by way of example with reference to the accompanying drawings, in which: Figure I illustrates a side elevational view in cross-section of a known arrangement of axle and sunwheel, Figure 2 shows an exploded perspective view of a sunwheel axle arrangement according to the invention, Figures 3a to 3c respectively show three steps in the formation of the axle shown in Figure 2, Figure 4 shows an end elevational view to a smaller scale of a sunwheel similar to that shown in Figure I, Figure 5 shows a side elevational view in cross section of the sunwheel shown in Figure 4, Figure 6 is a side elevational view of the sunwheel of Figures 4 and 5, Figure 7 is a side elevational view of an axle for the sunwheel of Figures 4 to 6, Figure 8 is a cross-sectional view along the section line X-X of Figure 7, Figure 9 is a detail view to a larger scale of part of the axle of Figure 7, Figure 10 is an exploded view similar to Figure 2 of an alternative arrangement, and Figure II is a modification of the arrangement shown in Figure 10.

Referring to Figure I, which shows a conventional sunwheel axle arrangement, the sunwheel 3 is slid over the axle I to the desired position and locked in this position by means of a pin 2 extending through aligned apertures in both sunwheel and axle. The apertures may be preformed or formed by drilling, with the sunwheel in position on the axle. The removal of material from both the axle and the sunwheel may weaken them and this can lead to failure.

Referring to Figure 2, a sunwheel shaft arrangement according to the invention is shown. In this arrangement a wing I is formed on the steel shaft 2 by displacing material. The wing I stands proud of the circular envelope of the shaft 2 and small indentations 3 are left extending into this envelope on opposite sides respectively of the wing I from which material has been displaced. Although not shown in Figure 2, diametrically opposed wings may be formed on opposite sides of the axle as can be seen in Figures 8 and 9.

The sunwheel 4 is formed with a corresponding slot 5 The circumferential width of the slot 5 is substantially equal to the circumferential width of the wing I so that when the sunwheel 4 is inserted over the axle 2 and slid along the wing I enters the corresponding slot so that the sunwheel is rotationally locked in position on the axle. A step 10 on the axle forms an axial stop for the sunwheel 4.

The wing I is formed on the axle 2 by a sequence of steps illustrated in Figures 3a, 3b and 3c of the drawings. An axle blank 6 is taken and opposing tools 7 and 8 are advanced from opposite sides towards it. As the blank 6 is gripped between the tools material of the axle blank is forced inwardly and upwardly to form the wing I. For simplicity the forming of one wing only is shown but two or more wings may be formed as desired. The tools 7, 8 shown are circular in cross-section but different shapes of tools can be used or desired.

Figures 4 to 9 show more views of an arrangement similar to that shown diagrammatically in Figure 2 in which equivalent parts bear the same reference numerals, but with two wings I and slots 5.

A further alternative arrangement to that shown in Figure 2 is shown in Figure 10. In this figure, equivalent parts are given the same reference numerals as in Figure 2. In this alternative arrangement, the axle is the same as in the arrangement of Figure 2, but the slot 5 in the sunwheel is formed as an internal keyway. Figure II shows a double keyway 5 arrangement. In both these arrangements the or each keyway wing pair cooperate as in the slot wing pair of the embodiment of Figure 2 to prevent relative rotational movement between the sunwheel and axle.

It will be appreciated that the above embodiment has been described by way of example only and that many variations are possible without departing from the scope of the invention.

Claims

1. A shaft and member assembly in which relative rotational movement of the member and shaft is prevented by coacting formations on the member and shaft, the formations on the shaft being formed by displacing shaft material.

2. A shaft and member assembly as claimed in Claim 1, in which the shaft is an axle of a gear system and the member is a sunwheel of that system mounted on the axle.

3. A shaft and member assembly as claimed in Claim 2, in which the formations comprise wings which are formed by displacing material from the normal circular envelope of the axle cross section.

4. A shaft and member assembly as claimed in Claim 3, in which the wings stand proud of the normal envelope.

5. A shaft and member assembly as claimed in Claim 4, in which when the sunwheel is inserted over the shaft axially extending slots in the sunwheel receive these wings to prevent relative movement between shaft and sunwheel.

6. A shaft and member assembly as claimed in Claim 5, in which the axially extending slots extend all the way through the material of the sunwheel from the inside to the outside or are formed as keyways internally of the sunwheel.

7. A method of locking a rotational member on a supporting shaft including the steps of displacing material from the shaft to form one or more formations, forming complementary formations in the member and introducing the member onto the shaft so that the formations on the shaft coact with the complementary formations on the member to prevent relative rotational movement.

8. A method as claimed in Claim 7, in which the material to form the wings is displaced by opposing tools which are pressed into the axle from opposite sides.

9. A method as claimed in Claim 8, in which one pair of tools is provided for each wing to be formed.

10. A method as claimed in Claim 8 or 9, in which the tools are circular in cross section.

11. A method as claimed in Claim 7, 8, 9 or 10, in which the formations on the shaft are machined.

12. A shaft and member assembly substantially as hereinbefore described with reference to Figs.2 and 3a to 3c or Fig.4 to 9 or to Fig.2 with the modification of Fig.10 or Fig.11.

13. A method of locking a rotational member on a supporting shaft substantially as hereinbefore described with reference to Figs.2 and 3a to 3c or Fig.4 to 9 or to Fig.2 with the modification of Fig.10 or Fig.11.