GB2254821A

GB2254821A - Transfer moulded plastics walled structure ,reinforced by fibrous stuctural members.

Info

Publication number: GB2254821A
Application number: GB9108415A
Authority: GB
Inventors: John James Mather
Original assignee: Motor Panels Wigan Ltd; Ribbons Ltd
Current assignee: Motor Panels Wigan Ltd; Ribbons Ltd
Priority date: 1991-04-19
Filing date: 1991-04-19
Publication date: 1992-10-21
Anticipated expiration: 2011-04-19
Also published as: GB9108415D0; GB2254821B

Abstract

The structure, e.g. a vehicle cab or body, comprises one or more structural members 8, 11 of reinforcing fibres, e.g. glass, carbon or kevlar (R.T.M) in the form of a mat, integrally joined by the transfer moulded plastics to one or more moulded plastics material wall panels 5, 6, 7. The or each structural member 8, 11 may include weight saving inserts 9, e.g. of a rigid foamed plastics material. The or each structural member is placed in a pre-determined orientation in a mould of a shape to form at least part of the walled structure, and liquid plastics material is injected to penetrate the structural member(s) and simultaneously form one or more wall panels of the structure. The fibres are selectively orientated to suit expected loads or stresses on the structure in use. A structure so made has the advantage of being lightweight yet structurally strong. <IMAGE>

Description

MOULDED WALLED STRUCTURES This invention relates to moulded walled structures comprising wall panels and supporting structural members.

Some examples of walled structures to which the invention is applicable are vehicle cabs and bodies, portable cabins, caravans, mobile homes, kiosks, other housings of various kinds and building structures.

There are other walled structures to which the invention may be applicable, as will be realised from the following disclosure.

Conventionally vehicle cabs and bodies have been made from metal sheet, commonly steel sheet, pressed and shaped to form wall panels of the cab or body of a desired configuration, and more robust metal frame members, usually of steel angle-section, box section or tube, secured together, as by welding, to form a framework to which the wall panels are fixed and which provides the greater part of the load bearing capability and structural stability of the constructed cab or body. The method is time consuming and expensive.

It is also known to manufacture the wall panels, or some of them, from glass fibre reinforced plastics resin or as plain plastics mouldings. These may be used without a metal framework in some constructions but they are of limited structural strength and for structures of any significant size a supporting framework is essential.

Other walled structures have conventionally been made in a comparable manner to vehicle cabs and bodies.

The present invention aims to provide a moulded walled structure which has advantages over the conventional structures.

According to a first aspect of the present invention a moulded walled structure is provided which is made by the resin transfer moulding process and comprises one or more structural members of reinforcing fibres integrally joined to one or more moulded plastics material wall panels.

According to a second aspect of the invention there is provided a method of manufacturing a moulded walled structure which includes the steps of forming one or more structural members of reinforcing fibres, placing the structural member or members in a pre-determined orientation in a mould having a cavity of the required shape of at least part of the walled structure, introducing liquid plastics material into the mould to penetrate the structural member or members and form one or more wall panels of the walled structure and curing the plastics material of the moulding thus formed.

The reinforcing fibres may, for example, be of glass, carbon or kevlar2. Combinations of fibres of different materials may be used. The fibres may be selectively orientated in the structural member or members to suit the loads and stresses expected to be exerted on the walled structure in use, and so enable the structure to resist those loads and stresses most effectively. At different parts of the walled structure the orientations of the reinforcing fibres may be changed as may be suitable for the expected loads and stresses on those parts.

The or each structural member is positioned in the walled structure as appropriate for reinforcement of the structure. For example, the member or members may be at corners, along an edge or edges of the structure, at intermediate positions of the wall panel or panels for additional support or strength, where there are changes in direction in the shape of the structure, around openings in the structure and/or at parts of the walled structure where attachments or other means are to be mounted on or in the structure.

The structural member or members may be solid or of hollow section, or may include one or more inserts for lightness and a saving in plastics moulding material. Conveniently the inserts are made of a foamed plastics material, such as foamed polyurethane or polyester, but other suitable materials may be used.

A complex framework of the structural members may be assembled in the mould, or be pre-assembled before introduction into the mould. Where inserts are included in the structural members, the inserts may be made and assembled together before the reinforcing fibres are applied to them.

Conveniently the reinforcing fibres are used in the form of a mat, which may be knitted or woven, in the forming of the structural member or members.

Thermoset or thermoplastic plastics moulding material may be used, as appropriate for the walled structure. An isophthalic polyester resin is one example of a suitable material.

A moulded walled structure in accordance with the invention may be an assembly of a plurality of unitary components each made by the resin transfer moulding process and comprising one or more structural members of reinforcing fibres integrally joined to one or more plastics material wall panels. The unitary components may be bonded together in the assembled walled structure.

By the invention it is possible to provide a relatively lightweight but structurally strong walled structure which has the inherent advantages of plastics material over metal such as steel regarding resistance to corrosion. The production of the structural members and the moulding process may be at least partially automated, which can facilitate production and reduce the labour and time involved. There can be substantial savings in production in repetitive manufacture of the walled structures. Very little finishing work may be necessary on the walled structures after the moulding process and curing. Colouring agents can be mixed with the plastics material so that the walled structures produced are of the required finished colour, thereby removing the need for painting.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which, Figure 1 is a diagrammatic perspective view of a vehicle cab made in accordance with the present invention; Figure 2 is an enlarged section through a structural member included in the cab structure; Figures 3 and 4 are enlarged fragmentary views of structural members included in the cab structure at the parts circled at A and B respectively in Figure 1; and Figure 5 is a fragmentary perspective view of an example of other structural members.

For convenience of illustration only the vehicle cab as shown in Figure 1 is reduced to a basic rectangular box shape. It comprises a body 1 having front and side windows 2, 3 and a door 4. The body is made by the resin transfer moulding process and has a front wall panel 5, side wall panels 6, a top wall panel 7 and a rear wall panel, not shown, integrally joined to and supported by structural members 8, as shown in Figures 2, 3 and 4. The structural members 8 extend along the free and joined edges of the body panels, and around the openings for the windows 2, 3 and the door 4. There may be additional structural members, for example at spaced intervals across the top wall panel 7.

In the drawings the structural members 8 are shown of simplified form for illustrative purposes. They may be of a variety of shapes (another example is shown in Figure 5) and sections as desired, and as may be suitable for the loads and stresses to which the cab may be expected to be subjected in use, and where they are positioned. Each of the structural members 8 has an insert, or core, 9, Figure 2, of a high density, rigid, expanded foamed plastics material enclosed reinforcing fibres 10 of glass, carbon and/or kevlar A applied as a mat around the insert 9. The structural members are provided principally as beams and stanchions. Others may be provided including some serving as gussets 11, Figure 3.At least the beam and stanchion members may have carbon reinforcing fibres extending longitudinally of the members for optimum tensile and compressive strength, and laterally extending glass reinforcing fibres for shear strength.

Other mixtures and orientations of the fibres may be found to be more suitable in some applications.

Oblique orientations of the fibres may be appropriate.

In general, the carbon fibres are provided where the greater loads and stresses are likely to be concentrated.

The orientation and types of fibres which are most suitable for particular structures can be determined by resolution of force and beam theories and test data.

In the manufacturing process of the body of the cab, the inserts 9 for the structural members are formed by moulding and the reinforcing fibres are laid as a mat over the inserts with the fibres orientated as required relative to the inserts. Surfaces of the cavity in the mould in which the body is to be moulded are coated with a gel, being a thixotropic resin containing colouring additives according to the finished colour desired for the body. The pre-formed structural members are laid on the gel in the mould in the required, pre-determined, positions. The mould is then closed and the moulding plastics material is injected to fill the cavity. The plastics material bonds to the gel and the fibres of the structural members. For the curing the formed moulding may be left in the mould or it may be removed from the mould when it is stable enough to complete the curing process outside the mould, possibly on a supporting jig. There may be subsequent heat treatment, as necessary.

Preferably in the mounting of the cab on a vehicle flexible mounts are used where possible so that some relative movement is possible between the cab and its support to absorb deflecting and shock loads on the one or the other and reduce the risk of consequential damage to the plastics material of the cab body.

Claims

1. A moulded walled structure which is made by the resin transfer moulding process and comprises one or more structural members of reinforcing fibres integrally joined to one or more moulded plastics material wall panels.

2. A moulded walled structure according to Claim 1 wherein there is a plurality of the structural members and of the wall panels, and at least some of the structural members extend along free and joined edges of the panels.

3. A moulded walled structure according to Claim 1 or Claim 2 wherein the wall panel, or at least one of the wall panels, has an opening therein, and there is a plurality of the structural members extending around the opening.

4. A moulded walled structure according to any preceding claim wherein the wall panel, or at least one of the wall panels, has the structural member or at least one of the structural members joined thereto at an intermediate part thereof.

5. A moulded walled structure according to any preceding claim wherein the fibres are of glass, carbon or kevlar/, or a combination of fibres of at least two of such materials.

6. A moulded walled structure according to any preceding claim wherein the structural member, or at least one of the structural members, is elongate and has reinforcing fibres extending longitudinally thereof for tensile and compressive strength.

7. A moulded walled structure according to Claim 6 wherein the longitudinally extending reinforcing fibres are carbon fibres, and the, or the or each respective, structural member has laterally extending reinforcing fibres of glass.

8. A moulded walled structure according to any preceding claim wherein the structural member, or at least one of the structural members includes one or more weight saving inserts.

9. A moulded walled structure according to Claim 8 wherein the or each insert is made of a foamed plastics material.

10. A moulded walled structure according to any preceding claim which comprises a plurality of unitary components each made by the resin transfer moulding process and comprising one or more of a plurality of the structural members integrally joined to one or more of a plurality of the wall panels, and the unitary components being bonded together in the walled structure.

11. A moulded walled structure according to any preceding claim which is a vehicle cab or body.

12. A moulded walled structure according to Claim 11 which has flexible mounts whereby it is adapted to be connected to a support on a vehicle.

13. A method of manufacturing a moulded walled structure by the resin transfer moulding process which includes the steps of forming one or more structural members of reinforcing fibres, placing the structural member or members in a pre-determined orientation in a mould having a cavity of the required shape of at least part of the walled structure, introducing liquid plastics material into the mould to penetrate the structural member or members and form one or more wall panels of the walled structure and curing the plastics material of the moulding thus formed.

14. A method according to Claim 13 wherein the fibres are selectively orientated in the structural member or members to suit the loads and stresses expected to be exerted on the walled structure in use.

15. A method according to Claim 13 or Claim 14 wherein the fibres comprise fibres of glass, carbon or kevlart or a combination of fibres of at least two of such materials.

16. A method according to any of Claims 13 to 15 wherein the structural member, or at least one of the structural members, includes one or more inserts for a saving in weight and plastics moulding material in the, or the respective, structural member.

17. A method according to Claim 16 wherein the or each insert is made of a foamed plastics material.

18. A method according to Claim 16 or Claim 17 wherein the or each insert is made and assembled in its required position for inclusion in the, or the respective, structural member before the reinforcing fibres are applied for the forming of the structural member.

19. A method according to any of Claims 13 to 18 wherein a number of the structural members are assembled together in the mould to form a framework in the mould.

20. A method according to any of Claims 13 to 18 wherein a number of the structural members are pre-assembled to form a framework before introduction into the mould.

21. A method according to any of Claims 13 to 20 wherein the reinforcing fibres are used in the form of a mat in the forming of the structural member or members.

22. A method according to any of Claims 13 to 21 wherein the plastics material is an isophthalic polyester resin.

23. A method according to any of Claims 13 to 22 wherein a colouring agent is mixed with the plastics material such that the or each wall panel formed from the plastics material is of the required finished colour of the manufactured walled structure.

24. A moulded walled structure substantially as described herein with reference to the accompanying drawings.

25. A method of manufacturing a moulded walled structure substantially as described herein with reference to the accompanying drawings.