GB2213461A

GB2213461A - Manufacture of shafts of fibre-reinforced composite material

Info

Publication number: GB2213461A
Application number: GB8828821A
Authority: GB
Inventors: Miloslav Petrzelka
Original assignee: Uni Cardan AG
Current assignee: GKN Automotive GmbH
Priority date: 1987-12-12
Filing date: 1988-12-09
Publication date: 1989-08-16
Anticipated expiration: 2008-12-09
Also published as: IT8805250A0; JPH01201568A; GB8828821D0; JPH039226B2; GB2213461B; IT1226395B; ES2013376A6; FR2624424A1; DE3742255C1

Description

r,L 1 GMD/8704OGB1 n e. 4 2 j,46 1 MANUFACTURE OF SHAFTS OF

FIBRE-REINFORCED COMPOSITE MATERIAL This invention relates to a method of manufacturing a hollow shaft from a fibre-reinforced composite material, by applying at least one fibre continuously to and fro to a mandrel. In referring to applying the fibre continuously to and fro to the mandrel, we mean that the fibre is applied in successive passes lengthwise of the mandrel and following application of the fibre to the mandrel in a pass in one direction lengthwise thereof, the direction of application is reversed and the same fibre is applied to the mandrel in the opposite direction. In referring to a fibre, we include a roving or thread of fibres.

Manufacture of shafts, e.g. of fibre-reinforced plastics material, in the above manner is well-known. It is usual to apply fibres, usually in the form of rovings or threads comprising a large number of individual fibres, to the mandrel in a number of layers in which the fibres are disposed at different helix angles relative to the axis of the mandrel, in order to give the shaft the required properties to transmit torque and resist bending in service. There may even be fibres extending longitudinally of the shaft parallel to the axis thereof. One area of difficulty in such shaft manufacture is that of holding the fibres at the ends of the mandrel where their direction of application to the mandrel lengthwise thereof is reversed, and in particular the use of external devices for holding the fibres at the ends of 2 the mandrel has been proposed. This, however, requires sophisticated technical facilities, and waste occurs at the ends of the shaft.

in DE-3247889 there is disclosed a process in which a form-fitting connection of a fibre-reinforced composite bar is achieved with conical connecting elements, with clamping rings or wires which draw in and hold the fibres in circumferential grooves on the connecting elements. This means that the connecting elements have to have a very complicated design. The way in which the fibres are guided in the region of the individual circumferential grooves means that inhomogeneities are produced in the tubular fibre-reinforced bar, adversely affecting its strength. Additionally, the fibres can easily be damaged at the edges of the grooves in the connecting elements.

It is an object of the present invention to provide a method of manufacturing a hollow shaft of fibre-reinforced composite material,, wherein the above described disadvantages are overcome or reduced.

Particularly it is aimed to produce shafts which do not require specially adapted connecting elements, which will not involve waste at the ends of the shaft, and wherein the end regions will be characterised by a high degree of homogeneity.

According to the present invention, we provide a method of manufacturing a hollow shaft of fibre reinforced composite material, by applying at least one fibre continuously to and fro to a mandrel, wherein the or each fibre is held Cor reversal of its direction of application to the mandrel, at an end part of the shaft, by at least one auxiliary fibre wound onto the mandrel.

1 1 3 1 A shaft made by the method according to the invention is suitable for connection to a smoothly surfaced cylindrical or slightly tapering connecting element. The end regions of the shaft are reinforced by the auxiliary fibres, and no waste is produced. The technical facilities required for putting the method into effect are basically simple as required anyway for shaft manufacture, and, particularly if several devices for applying the fibres to the mandrel are provided, production is rapid and inexpensive.

Preferably the auxiliary fibre is wound helically to and fro on the mandrel over a length thereof at a large winding angle relative to the axis of the mandrel and preferably in several layers, to provide the shaft with a reinforced connecting region. In this way, the connecting region of the shaft at the end thereof has a fabric-like fibre structure. If suitable dimensions and winding speeds are selected, additional outer windings to reinforce the connecting region are no longer required.

Inter-laminar shear stresses which occur with such external winding devices are not present when the shaft is produced in accordance with the method of the present invention.

Preferably the application of the fibres is carried out by rotating the mandrel whilst guiding devices for applying the fibres are reciprocated lengthwise of the mandrel.

If there are several devices for applying the fibres continuously to the mandrel, reciprocating lengthwise of the mandrel in such a way that they are displaced in phase from one another, it is possible to operate with a single device for applying the auxiliary fibre to the A.

4 mandrel at each end of the shaft. However, it would also be possible to provide several circumferentially spaced devices for applying auxiliary fibres, which may rotate about the mandrel In the direction opposite to that in which the mandrel is rotating. At the same time, as described above, such devices may move axially or to and fro relative to the mandrel at an appropriate speed.

In order to produce the necessary forces for holding the fibres, the or each auxiliary fibre may be braked by its guiding device.

The invention also provides a shaft made by the method of the invention.

The invention will now be described by way of example with reference to the accompanying drawing, which shows diagrammatically how the method is carried out.

The drawing shows a cylindrical mandrel 1 which is driven so as to rotate, in the direction indicated by arrow 10, about its longitudinal axis 11. A fibre thread or roving 4 is shown being applied to the surface of the mandrel as the latter rotates, the thread 4 being drawn from a supply spool thereof and passed through a guiding device 2 which is reciprocated lengthwise of the mandrel, along the entire or substantially the entire length thereof, so that the thread is applied continuously to the surface of the mandrel helically. At the end of the mandrel, an auxiliary fibre thread or roving 5 is applied to the surface of the mandrel from a guiding device 3, the auxiliary thread 5 being wound nearly circumferentially of the mandrel (in a helix whose angle is inclined by nearly 90' to the axis 11 of the mandrel). The auxiliary thread 5 holds the thread 4 to the mandrel C1 z 0 at the point where the direction of movement of the guiding device 2 is reversed relative to the mandrel adjacent the end thereof, to produce the point 6 of the reversal of the direction of application of the thread to the mandrel. To ensure that the auxiliary fibre thread 5 is applied under sufficient tension to hold the fibre thread 4, the guide device 3 for the auxiliary thread preferably incorporates a braking device.

In manufacture of a shaft, the movement of the fibre thread guiding devices 3 and 2 relative to the mandrel would, of course, be controlled so that the reversal points 6 are distributed circumferentially around the mandrel. The movement of the guide device 3 for the auxiliary thread may be controlled so that the auxiliary thread 5 is wound in a number of layers at a high winding angle, so that the end region of the shaft is reinforced to receive a connecting element. Thus the guide device 3 may be reciprocated lengthwise of the mandrel over the indicated short part of the length thereof, the device 3 being moved towards the centre of the mandrel after having produced a reversal 6 of the fibre thread 4 and then back towards the end in readiness for the next such reversal.

It is possible to provide several thread guiding devices 2 circumferentially spaced about the mandrel, reciprocating therealong in an appropriately phased relationship to one another, and it is also possible to provide several circumferentially spaced guiding devices 3, which may rotate about the mandrel in the direction opposite to the direction of mandrel rotation, for auxiliary threads. It will be appreciated, of course, that a further thread guiding device 3 or a number thereof would be provided at the other end of the mandrel 6 to secure the fibre thread (or threads) 4 at its or their reversal points at the other end of the shaft being manufactured.

The end regions of the shaft, where the continuous fibres are held by the auxiliary fibres for reversal of their direction of application to the mandrel, may be cylindrical or slightly conical.

1 p Z1 7

Claims

1. A method of manufacturing a hollow shaft of fibre-reinforced composite material, by applying at least one fibre continuously to an fro to a mandrel, wherein the fibre is held for reversal of its direction of application to the mandrel, at an end part of the shaft, by at least one auxiliary fibre wound onto the mandrel.

2. A method according to Claim 1 wherein the auxiliary fibre is wound helically to and fro over the mandrel over a length thereof at a large winding angle relative to the axis of the mandrel, to provide the shaft with a reinforced connecting region.

3. A method according to Claim 1 or Claim 2 comprising rotating the mandrel.

4. A method according to any one of the preceding claims comprising reciprocating a number of continuousfibre-applying devices lengthwise of the mandrel in a phase-displaced relationship to one another.

5. A method according to any one of the preceding claims comprising applying a number of auxiliary fibres to the mandrel from auxiliary fibre-applying devices spaced circumferentially about the mandrel.

6. A method according to Claim 5 comprising moving said auxiliary fibreapplying devices lengthwise of the mandrel.

7. A method according to Claim 5 or Claim 6 comprising rotating said auxiliary fibre-applying devices about the 8 mandrel in the direction opposite to the direction of rotation of the mandrel.

8. A method according to any one of the preceding claims comprising braking the or each auxiliary fibre in its applying device.

9. A method according to any one of the preceding claims wherein, after having produced a reversal in the direction of application of the continuous fibre to the mandrel, the auxiliary fibre is wound helically towards the centre of the shaft and back to the end thereof.

10. A hollow shaft made of a fibre-reinforced composite material, comprising fibres continuously helically extending in opposite directions lengthwise of the shaft, and held for reversal of their direction at the ends of the shaft by auxiliary fibres extending helically in end regions of the shaft.

11. A shaft according to Claim 10 wherein said end regions of the shaft are cylindrical.

12. A shaft according to Claim 10 wherein said end regions of the shaft are slightly conical.

13. A method of manufacturing a shaft, substantially as hereinbefore described with reference to the accompanying drawing.

14. A shaft made by a method according to any one of Claims 1 to 9, or Claim 13.

Published 198D atThePatent Office. State House. 66,71 High Holborn, IoondonWClR4TP.Further copies maybe obtainedfrom The Patent Office. Wes Branch, St Mary Cray, Orpington_ Kent BRs 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con- 1187 f