Apparatus for forming the end portions of fibre reinforced thermoplastic composite tubes

Abstract

A method and apparatus for forming at least one external annular flange (48 or 49) adjacent one end of a fiber reinforced thermoplastic tube (10) in which the tube (10) is mounted on a mandrel (12) and a first end portion of the tube is clamped in a collar (13) having at least one internal annular cavity (18 or 19) for forming a flange, a second end portion of the tube in the region (R1, R2) of the cavity is heated to soften the thermoplastic, and an axial load (L) is applied to the end of the tube by a piston (24) causing the softened tube to flow into the cavity (18, 19) in the collar (13) to form a flange on the tube.

Claims

1. Moulding apparatus for forming at least one flange adjacent an end portion of a wound fibre reinforced thermoplastic tube, said apparatus comprising a cylindrical collar having a respective annular cavity on its inner surface for forming each flange, at least one heat source, and a piston coaxial with the cylindrical collar for exerting an axial load on the end of the tube, the collar having a first portion providing a clamping zone for gripping an first end portion of the tube, a second portion heating the tube in the region of the cavity, and a third portion housing the piston so as to apply a load to the end of the tube causing a heated portion thereof to bend and flow into said cavity.

2. Apparatus as claimed in claim 1, wherein the collar has two annular cavities, the second of which is nearer the piston, and said second portion of the tube is in the region of both cavities, the heat source softening the tube firstly in the region of the first cavity and then softening the tube in the region of the second cavity, the tube material being caused to bend and flow firstly into the first cavity and then into the second cavity under an axial load generated by the piston to form two integral flanges on the tube.

3. Apparatus as claimed in claim 1, wherein the collar has a heat source for each cavity, each heat source softening the tube in the region of each cavity and being operated in turn.

4. Apparatus as claimed in claim 1, wherein the tube is held on a mandrel and the piston is slidably mounted on the mandrel.

5. Apparatus as claimed in claim 4, wherein a heat source may be provided within the mandrel.

Description

DESCRIPTION OF THE DRAWINGS

(1) The invention will be described by example and with reference to the accompanying drawings in which:

(2) FIG. 1 is a schematic drawing of apparatus according to the present invention showing a first step in the method also according to the Invention,

(3) FIG. 2 shows a second step in the method of the invention,

(4) FIG. 3 is final step in the method of the invention,

(5) FIG. 4 is tube having integrally formed flanges and groove in accordance with a further aspect of the Invention

(6) FIG. 5 shows an alternative apparatus in which the heat source is located within the mandrel 12.

DETAILED DESCRIPTION OF THE INVENTION

(7) With reference to FIGS. 1 to 3, there is shown a fibre reinforced thermoplastic composite tube or pipe 10 which may be formed from any reinforcing fibre and any thermoplastic resin matrix. Preferably, the composite tube comprises substantially continuous reinforcing fibres, such as glass fibre and/or carbon fibre and the thermoplastic matrix could be any thermoplastic, preferably one of PEI (polyetherimide), PPS (Polyphenylenesulpone), PAI (Polyamide-imide), PES (polyethersulphone) and more preferably PEEK (Polyetheretherketone).

(8) The thermoplastic composite tube 10 is placed on a mandrel 12, and the composite tube 10 is then clamped within a cylindrical collar 13. The collar 13 is preferably a split collar (split into arcuate segments) and comprises at least three zones, a clamping zone 14, a heating zone 15 and a compression loading zone 16. The heating zone is provided with at least one heat source 17 and has internal annular cavities 18,19 on its inner surface which will define the final shape of the composite tube end. The clamping force from the cylindrical collar 13 restrains any movement of the composite tube along the axis of the mandrel 12. The clamping zone may also conduct heat away from the adjacent tube 10 keeping the tube rigid/solid in that region. A piston 24 is coaxial of the collar 13 is slidably mounted within the compression zone 16 of the collar. The piston 24 has an internal through bore 23 which is slidable on the mandrel 12 and has a recess 22 in its front face to receive the end portion 21 of the tube 10.

(9) The zones 13,14 and 16 may be formed as separate components which are then brought together to form the collar.

(10) During the first stage of the process, as shown in FIG. 1, the tube is clamped by the collar 13 to prevent axial movement and heat emitted from the heat source 17 is applied in the region R1 of the first and nearest cavity 18. The heat softens the composite in the region R1 of the cavity while the piston 24 slides over the mandrel 12 applying an axial load L to the composite tube 10.

(11) In an alternative arrangement, the piston 24 may be static and the collar 13 moved towards the static piston.

(12) Referring now to FIG. 2, the axial movement of the piston 24 causes the soft region R1 of the composite tube to bend and flow filling the first cavity 18 as shown. By this stage, the continuing applied heat melts the thermoplastic matrix, allowing the cavity 18 closest to the heat source to be fully filled.

(13) Referring now to FIG. 3, as the heat source 17 continues to emit heat, the composite pipe 10 further softens and the now softened region R2 further includes material adjacent the cavity 19 furthest from the heat source 17. The axial load exerted by the continuing sliding action of the piston 24 causes the second cavity 19 to be filled. The continuing applied heat eventually melts the thermoplastic matrix in the second cavity 19 and the cavity is fully filled.

(14) The melt temperature of the thermoplastic coupled with the heat output from the heat source 17 may in some cases cause the regions R1 and R2 to soften at substantially the same time.

(15) The instant at which the cavities 18 & 19 are fully filled with the formed composite coincides with the instant at which the piston 24 reaches its final position, fully engaged with the matching compression zone 16 on the collar. At this instant the heat source is stopped and the molten thermoplastic composite gradually returns to its solid state.

(16) The final shape of the composite tube 10 is shown in FIG. 4 and now includes integrally formed annular flanges 48, 49 with an annular slot or groove 41. The groove 41 may be used to accommodate an O-ring for connection to other surrounding components. Such a connection may be useful for tubes which transport fluids, for example fuel pipes used in aircraft.

(17) In an alternative arrangement, shown in FIG. 1 only, a second heat source 27 may be provided adjacent the second cavity 19 so that for each cavity 18 & 19, each respective heat source 17 & 27 softens the tube in the region of each respective cavity. The two heat sources are operated in turn to first soften the region which fills the cavity 18 and then to soften the region which fills the cavity 19.

(18) A further arrangement is shown in FIG. 5 in which a heat source 37 is provided within the mandrel 12. The internal heat source 37 may be provided as an alternative to the external heat sources 17 and/or 27 or as an alternative thereto.