GB2394480A

GB2394480A - Retaining a gaiter by winding wire around it

Info

Publication number: GB2394480A
Application number: GB0224882A
Authority: GB
Inventors: Magnus Cooper
Original assignee: NSK Steering Systems Europe Ltd
Current assignee: NSK Steering Systems Europe Ltd
Priority date: 2002-10-25
Filing date: 2002-10-25
Publication date: 2004-04-28
Anticipated expiration: 2022-10-25
Also published as: GB0224882D0; GB2394480B

Abstract

A method and apparatus for fastening gaiters 1, 2 on to an item having a generally circular cross section 3, such as a constant velocity joint body housing, is provided. The method includes the steps of drawing wire 9 from a stock and feeding it to the gaiters 1, 2. The wire 9 is sprung to resiliently curl about the gaiters 1, 2. This may be achieved by a deforming tool 12 which may impart to the wire 9 a radius of curvature less than the radius of the gaiter 1, 2 such that in the completed product the coiled wire exerts a compressive force to the gaiters 1, 2 to hold them in place.

Description

- 1 RETAINING A GAITER ON AN ITEM

SUCH AS A CONSTANT VELOCITY JOINT BODY HOUSING

This invention relates to a method and apparatus for retaining a gaiter on an item such as a constant velocity joint body housing.

10 Elastic gaiters are often used to protect items such as constant velocity joints from exposure to environmental contamination.

The gaiter often requires additional means of 15 retention and/or sealing at one or more places where it is attached to a shaft, joint body or other item.

The function just described is commonly achieved using a resilient band, clamp or clip that fastens around 20 the gaiter and exerts an inward force upon it.

Such devices may suffer from one or more of the following drawbacks, especially pertaining to mass production of an assembly: i. The retaining device(s) may be difficult to assemble over the bellows of the gaiter.

ii. The or each retaining device may require an 30 additional operation to tighten it once it is in the correct position.

iii. The devices may present problems in handling, becoming entangled with each other and which having 35 to be individually presented to the assemblies.

- 2 iv. The devices may amount to a substantial cost when purchased in large quantities. There may be additional costs associated with handling and inspection of the parts.

v. The devices may be time-consuming to fit and tighten. A process is described in a Japanese Patent 10 Application (Publication No. 6-74249) in which a band of material fed from a stock is automatically wrapped around a gaiter to secure it in position. The process involves some forming of the band and a welding operation to join the ends of the band together.

According to one aspect of the present invention, there is provided a method of fastening a gaiter or the like on to an item having a generally circular peripheral outer surface or cross-section, the method including 20 drawing wire from a stock and feeding the wire to the gaiter, the wire being sprung in such a manner that it resiliently curls about the gaiter to secure the gaiter in place.

25 The wire may be so sprung by using a deforming tool to impart to the wire a radius of curvature less than the mean diameter of the region of the gaiter about which the . W1 re Is wrapped.

30 To facilitate the wrapping of the wire about the gaiter, the gaiter, together with the item about which the gaiter is fitted, is rotated at substantially the same speed as the speed of approach of the sprung wire.

According to another aspect of the present invention, there is provided apparatus for fastening a gaiter or the like on to an item having a generally circular peripheral outer surface or cross-section, the 5 apparatus including means to draw wire from a stock, means to feed the wire through the gaiter and means to spring the wire in such a manner to cause it to resiliently curl about the gaiter to secure the gaiter in place. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Fig. 1 is a perspective view of apparatus for wrapping by wire a gaiter or the like on to an item having a generally circular peripheral cross-section, 20 Fig. 2 is a diagrammatic end view, partly in section, of part of the apparatus shown in Fig. 1 and illustrates wire being drawn from stock and being deformed as it approaches the gaiter, 25 Fig. 3 is a view similar to Fig. 2 and shows a progressive stage of the wire feeding, where the wire is wound onto a rotating product and is prevented from bowing by the use of guideways and/or rollers, 30 Fig. 4 is a view similar to Fig. 3 and shows a final stage of the method, where the wire is severed so that a free end of the wire springs towards the gaiter,

- 4 Fig. 5 is a sectional view, showing a gearing system and a guideway system of the apparatus for controlling drum hatches of a drum, 5 Fig. 6 is a view similar to Fig. 5 and shows a progression of the part of the apparatus shown in Fig. 5, where the drum rotates and the hatches remain shut, Fig. 7 is a view similar to Fig. 5 and showing a 10 further step in the progression of the operation of the apparatus, where the drum has stopped with the hatch uppermost and the hatch is opened by means of a peg and a moving section of guideway, 15 Fig. 8 is a perspective view of the apparatus from underneath, and Fig. 9 is a perspective view of the apparatus shown in Fig. 1 and showing a completed product at an end stage 20 of the operation of the apparatus, with the hatches open with the product laying in the drums.

The method will now be described by example of the fastening of two overlapping gaiters 1,2 onto a constant 25 velocity joint (CVJ) central housing 3. In this case the CVJ forms part of a automotive steering shaft assembly having also input and output shafts 4, 5.

It is to be understood that, whilst the term used 30 herein is gaiter, the invention also embraces items known as boots and other similar items intended to protect apparatus from a hostile environment.

- 5 The gaiters 1, 2 are assembled into their correct positions on the CVJ central housing 3, and the assembly is placed into an apparatus 6,7 that rotates the assembly about its axis. The apparatus is formed as a pair of 5 spaced-apart, rotatable drums 6, 7, the drum 6 being adapted to hold the input shaft 4 and the drum 7 being adapted to hold the output shaft 5.

Wire 9 is fed by rollers 10 from a spool (not shown) 10 and emerges from a quill or nozzle 11, whereupon it is driven against a deforming tool 12 in such a manner that the wire 9 is distorted and henceforth curls towards the CVJ and gaiter assembly. The resultant free radius of curvature imparted to the wire 9A is slightly smaller 15 than the diameter of the item (outer gaiter 1) about which it is to be wrapped.

The curled wire 9A approaches the edge of the rotating product at a speed that matches the speed of the 20 periphery of the gaiter 1,2 (see Fig. 2). The wire then begins to wrap around the gaiter. As it does, it is stressed elastically to attain an inside radius of curvature equal to the radius of the gaiter onto which it wraps. One or more guideways 13 and/or rollers 14 may be 25 employed adjacent to the gaiter 1,2 in order to prevent the wire 9 from bowing away from the gaiter (illustrated in dotted lines in Fig. 3). This problem is most likely in an initial stage of the wrapping process.

30 The product continues to rotate and wire is simultaneously fed to it in the manner described until a required number of coils have been produced around the circumference of the gaiter 1,2.

6 - In the event of more than one coil being produced, the subsequent coils may be required to lie side-by-side on the gaiter in a predetermined manner. To facilitate this end, the initial direction at which the curled wire 5 9A leaves the nozzle 11 and deforming apparatus 12, may be set so that the direction of its emergence includes a minor component in the direction of the product axis 8.

The plurality of coils so produced will then lie adjacent to each other to form a helix.

Nevertheless, if several coils are required so that the axial length of the resulting helix is considerably greater than the diameter of the wire, then problems of overlapping coils could occur. In this case it may 15 necessary to displace the nozzle 11 and wire deforming apparatus 12 relatively to the product simultaneously to the wire 9 being wrapped around the gaiter 1,2. The direction of this traversing motion will be generally parallel to the direction of the axis of rotation 8 of 20 the product. The relative velocity of the traversing motion should be so as to move a distance equal to one pitch of the desired helix for every rotation of the product. The means of synchronized traversing here described are not shown in the illustrated embodiment but 25 will be appreciated by persons skilled in the art.

When the required number of coils have been produced around the circumference of the gaiter 1,2, the rotating motion and wire forming processes are ceased. A cutter 30 15 (Fig. 4) then severs the wire 9 at a point between the deformer 12 and the product. Because the entire severed portion of the wire 5B (Fig. 4) has been strained to a free radius of curvature that is less than the radius of the gaiter 1,2, it will immediately spring towards the

- 7 gaiter as shown in Fig. 4 and will not then protrude to any great extent from the gaiter surface on which it lies. 5 Because the fastener so produced would have a free radius of curvature that is less than the radius of the gaiter 1,2 on which it is wrapped, and because it is manufactured from a resilient (springy) type of wire 9, it will henceforce exert a compressive force upon the 10 gaiters 1,2 which will serve to secure them in position and help to seal the product against contamination, as is the function of most gaiter fasteners.

In the illustrated embodiment, the part of the 15 machine that holds and rotates the product takes the form of the rotatable drums 6,7. The drums are fitted with hatches 16,17 that extend the entire length of each drum.

The hatches 16,17 are openable to allow the product to be inserted and removed. When the product is placed into 20 the drums and the hatches are then shut, the product is gripped in the correct position for performing the wire wrapping process. The gaiters 1,2 are then co-axial with the axis of rotation 8 of the drums (6,7).

25 In the illustrated embodiment the drums 6,7 are equipped with gears 18 at either end. The gears are driven by means of drive shafts 19, 20 having pinions 21 engaged with the gears 18. The drive shafts 19, 20 are synchronized so that they have equal speed and direction 30 of rotation. In the illustrated embodiment, a synchronizing device 22 for this purpose takes the form of a belt drive, but other methods are possible. The drive shafts 19, 20 rotate in bearings 23 which themselves are rigidly attached to the base of the

- 8 machine. Because the drive shafts 19, 20 are synchronized to each other and are disposed on approximately opposite sides of the drums 6, 7 to which they are engaged, the drums themselves are held in 5 position by the meshing gears 18 and pinions 21 and have therefore no need of conventional bearing means. Fig. 5 best illustrates how the synchronized pinions 21 and meshing gear teeth retain the drums 6,7 on their correct axes. Because the drums 6,7 are not equipped with conventional bearings, their hatches 16, 17 open along the entire length of the drums and are therefore able to accommodate products having very long input shafts 4 15 and/or output shafts 5. Conventional bearings fitted to these drums could block the entry and egress of such products. Because the shafts 4, 5 of the product are loaded 20 into the drums 6, 7 in a generally radial direction, the drums themselves can be positioned closely to the point of application of the wire 9. Obviously a much simpler device could be used to retain and rotate the product.

However, this would have to grip the product at or near 25 its ends. Therefore the process is more liable to be affected by bending flexure of the product or by run-out present in the product, especially if the shafts 4, 5 are of considerable length.

30 Furthermore, the machine illustrated could be used in the manufacture of several different variants of steering shaft, which share the same CVJ body structure 3 but differ in the lengths of the shafts 4, 5. No re

- 9 - setting of the machine would be required to accommodate these different product variants.

Likewise, a mechanism is provided for opening and 5 shutting the drum hatches 16, 17 which itself does not obstruct the entry and egress of long products when the hatches are in the open position. The hatch operating mechanism consists of a circular track or guideways having a fixed portion 24 and a moving portion 25. A peg 10 26 attached to the drum hatch 16 or 17 is slideable in the guideway. When the drums 6, 7 are rotating, the guideways 24, 25 are held together to form a complete circle. The peg 26 moves around this as the drum rotates, and the constraining path of the circular 15 guideway prevents the hatch from opening (See Fig. 6).

When the drums are stationary with the hatches 16, 17 in an upper position, the peg 26 is in the moving section of the guideway 25. The moving part of the guideway 25 can then be moved away from the fixed part 24. This action 20 then opens the hatch 16, 17 by means of the peg 26 (see Fig. 7). An actuator 27 is provided to open and shut the hatches. As previously stated, the speed at which the wire 9 25 is propelled onto the gaiter 1, 2 should be matched to the speed of the periphery of that gaiter. There are of course many ways in which this can be achieved. The most straightforward of these would involve some mechanical link to synchronize the two functions just mentioned and 30 yield the correct ratio of speed. However, methods of synchronization that do not involve a fixed-ratio mechanical drive will offer the following advantages:

- 10 (a) The relative speeds may be finely adjusted in order to produce the most satisfactory result.

(b) The number of coils (turns) of wire 9 around the 5 gaiter does not have to be an integer. The wire wrapping can cease, the wire can be cut and then the drums 6, 7 can rotate in isolation to the correct position for the hatches 16, 17 to be opened.

10 (c) If there is slippage of the wire 9 against the rollers 10, or other problems relating to synchronization, then these could be automatically monitored and corrected for by a feedback loop control system.

It will be appreciated that the fastener does not have to be manipulated into position over the gaiter bellows or any other item.

20 Moreover, the fastener may be automatically fitted to the correct tension. There is no manual operation required to tighten the fastener and therefore there is no possibility of the fastener having been applied but not correctly tightened due to human error.

The material for the fasteners can be supplied in bulk spools, therefore handing is much simplified. Also, the material cost of the wire may be much lower than that of ready-made fasteners, so the method described above 30 may yield a cost saving in high-volume production.

The process can be automatic apart from the loading and unloading (even this could possibly be done by a robot). Therefore the operator's time is saved.

If two or more gaiter fasteners are required on the assembly, and these are to be produced about a common axis, then they may be produced simultaneously by using equipment having a plurality of quills 11, forming tools 5 12, etc. There is no special sequence of forming operations such as those described in Japanese Patent Publication No. 6- 74249.

It will also be appreciated that no welding operation is required and therefore the gaiter is not exposed to any heating and also there is no risk of improper (weak) weld formation.

If it becomes necessary to remove the fastener, this can be done without using sharp cutting tools and without destroying the fastener.

Claims

1. A method of fastening a gaiter or the like on to an item having a generally circular peripheral outer surface or cross-section, the method including drawing wire from a stock and feeding the wire to the gaiter, the wire being sprung in such a manner that it resiliently curls about the gaiter to secure the gaiter in place.

10

2. A method according to claim 1, wherein the wire is caused to be sprung by using a deforming tool to impart to the wire a radius of curvature less than the mean diameter of the region of the gaiter about which the wire is wrapped.

3. A method according to claim 1 or 2, wherein to facilitate the wrapping of the wire about the gaiter, the gaiter, together with the item about which the gaiter is fitted, is rotated at substantially the same speed as the 20 speed of approach of the sprung wire.

4. A method according to claim 3, wherein an initial direction of sprung wire is set so that the direction includes a minor component in the direction of 25 the axis of rotation of the gaiter.

5. A method according to any one of the preceding claims, wherein at least one guideway and/or roller is employed adjacent the gaiter in order to prevent the wire 30 from bowing away from the gaiter, in particular during an initial stage of the wrapping process.

6. A method according to any one of the preceding claims, wherein the direction of feeding of the wire is displaced along the gaiter to accommodate a plurality of coils of wire about the gaiter.

7. A method according to any one of the preceding claims and including the step of cutting the wire so as finally to secure the gaiter.

10

8. A method according to any one of the preceding claims, and being a method of fastening a gaiter on to a constant velocity joint body housing.

9. A method of fastening a gaiter or the like on 15 to an item, substantially as hereinbefore described, with reference to the accompanying drawings.

10. A gaiter or the like fastened on to an item by the method according to any one of the preceding claims.

11. An apparatus for fastening a gaiter or the like on to an item having a generally circular peripheral outer surface or cross-section, the apparatus including means to draw wire from a stock, means to feed the wire 25 through the gaiter and means to spring the wire in such a manner to cause it to resiliently curl about the gaiter to secure the gaiter in place.

12. An apparatus according to claim 11 and 30 including a deforming tool to impart to the wire a radius of curvature less than the mean diameter of the region of the gaiter about which the wire is to be wrapped.

- 14

13. An apparatus according to claim 11 or 12 and comprising means to rotate the gaiter, together with the item about which the gaiter is fitted, at substantially the same speed as the speed of approach of the sprung 5 wire.

14. An apparatus according to claim 11, 12 or 13 and including a cutter to cut the wire to complete the wrapping of the gaiter.

15. An apparatus according to any one of claims 11 to 14, and including at least one guideway and/or roller adjacent to where the gaiter is to be wrapped in order to prevent the wiring from bowing away from the gaiter.

16. An apparatus according to any one of claims 11 to 15, and including means to feed the sprung wire along the gaiter as wrapping progresses.

20

17. An apparatus according to any one of claims 11 to 16, and including spaced-apart rotatable drums with hatches into which the item to be wrapped by the gaiter can be laid and secured, with the gaiter being disposed between the rotatable drums.

18. An apparatus to fasten a gaiter or the like on to an item, substantially as hereinbefore described, with reference to the accompanying drawings.