AU681527C - Composite articles - Google Patents

Description

COMPOSITE ARTICLES

The present invention relates to composite articles in which an expanded plastics material is combined with an additional element.

According to a first aspect, the present invention provides a composite article comprising a first member and a second member integrally joined together with one member containing the other, or substantially so, the first member being of an expanded plastics material and the second member being of a denser material having generally greater strength characteristics than the material of the first member such that the composite article has overall an impact absorbing strength substantially greater than that of the first member.

The first member may be of a polyurethane foam the density of which can be selected according to the intended use of the composite article. Thus that part may range from being soft and pliable to being virtually solid. The foam may have a specific gravity as low as 0.03.

The second member is preferably made of a thermoplastics material although it may possibly be of another material or composite material. A plastics material can save on cost and weight. Plastics material having a specific gravity as low as 0.30 may be used. The plastics material may be formed to the required shape of the second part in any suitable manner. Extrusion and injection moulding but where possible vacuum forming is particularly convenient.

Depending upon the performance required from its structure, the materials of the composite article may be varied to give differing degrees of softness, flexibility, stiffness, absorption or crushability.

Different thermal requirements may be achieved by suitable selection of the materials.

The external surface of the composite article may have a raw material finish or it may be prepared or treated as appropriate to have one or more desired properties such as, to be, for example, UV stabilised, flexible, rigid, coloured or able to be coloured, resistant to salt, certain chemicals and/or oil, diesel oil or petroleum, energy absorbing and impact resilient.

The article may be made in a bar or generally bar-like form, sheet or other form.

In one particular embodiment, a composite article in accordance with the present invention is provided in the form of a bull bar, nudge bar or like protector for attachment to a vehicle.

Bull bars, nudge bars and like protectors may be attached, for example, to the front of a car, a van or another form of vehicle to reduce the risk of damaging the vehicle's bodywork in the case of a collision; they are often fitted to four wheel drive vehicles and vehicles suitable for use off-road. Traditionally, such protectors have been made of metal, usually steel, section and/or tube or bar. Whilst these constructions have generally been quite effective in protecting vehicles to which they are attached they can be hazardous to people or animals unfortunate enough to be struck by them even at low speeds. Although attempts have been made to reduce the force of an impact resulting from collision, for example, by providing an exterior layer of foam on a steel bar, such attempts have not had any significant effect in improving the safety of the protectors. The inherent rigidity of the known protectors and their substantial resistance to being deformed or to absorb energy upon impact contribute to their danger in collisions with people or animals.

In one embodiment of a bar in accordance with the first aspect of the invention the second member is in the form of an elastically deformable core element covered by the first member. The bar is capable of flexing upon impact if an object is struck and, unless the impact load is excessive, of subsequently resuming substantially its original shape, but also has sufficient strength to provide some protection to a vehicle to which it is fitted.

The flexing of the bar absorbs some of the energy of an impact and can reduce injury to a person or animal struck. Both members of the bar may contribute to the bar's flexibility and capacity for energy absorption.

The bar may be arranged with a point of weakness or a flexing point; this may be arranged to encourage the bar to bend or deform at a particular point along its length as a result of an impact. More than one flexing point may be provided. The flexing point or points may be arranged such that the way the bar deforms depends not only on the force of the impact but also on the position of the impact along the bar's length. The bar may deform or deflect at a position remote from the position of the point of impact.

The second member may be provided as a core, entirely encased within the first member of expanded plastics material. Where the expanded plastics provides the outwardly facing surface of a bar, for example, deformation of the expanded plastics surface upon contact with a colliding object increases the area of contact between the bar and the colliding object and thus reduces the pressure exerted by the bar on that object. This effect may also be beneficial in reducing or avoiding damage or injury caused by the bar.

The composite article, and its first and second members, may have any suitable shape and profile according to the intended use of the article. In the form of a bar, for example, the shape of the first and second members may be arranged to encourage flexing and deformation of both members upon impact and to encourage the distribution of forces and energy between both members. The two members are preferably fixed or bonded together during the forming process.

As mentioned the second member may be of a plastics material. Any suitable plastics material may be used.

The second member may be produced as a vacuum forming; one or more flexing points may be created as part of the vacuum forming process.

The expanded plastics material of the first member is conveniently an integral skin foam but it may be of another suitable material.

One or more additional elements may be incorporated into the composite article, for example for the purpose of fixing the article for use to a support, mounting or other article, or for attaching one or more other items to the article. The or each additional element may be incorporated into the article as an integral part of its structure, or the article may be adapted to have the or each additional element attached to it. It may be that at least one additional element is provided as an integral part of the structure of the article and the article is adapted to have one or more further elements attached to it.

Graphic, informational, promotional or other such display detail may be included in the composite article, conveniently as it is being formed.

According to a second aspect, the present invention provides a method of manufacturing a composite article in accordance with the first aspect of the invention set forth comprising the steps of:

(a) pre-forming the second member;

(b) arranging the preformed second member in a mould, and

(c) injecting an expanded plastics material into the mould to form the first member which surrounds the second member.

The second member may be encased by the expanded plastics material. The second member may be of a plastics material; it may have one or more flexing points defined in it as it is formed and it may be vacuum forme .

In a further embodiment, a composite bar in accordance with the first aspect of the invention is made in the form of a baton. Traditionally, batons used, for example, by the Police have been made of wood. One disadvantage of such known batons is the difficulty experienced by a user in judging how hard to strike with the baton to produce an effective warning blow to a recipient but without unintentionally causing serious injury.

The present invention, incorporating some or all of the features discussed above, is used in one embodiment to provide a baton capable of flexing in a desired way upon impact and of subsequently returning to its original shape. Such flexing may absorb some of the energy of impact and may make the judgement of how hard to strike less critical. The flexing may be substantially localised at a flexing point.

The baton may be provided with a side handle and some flexibility may be provided in the connection between the side handle and the baton's body.

The second member may be provided as a core encased within the expanded plastics material which forms the first member. The core may be of annular or other cross-section; the cross-section and/or wall thickness of the core need not be constant throughout its length. The baton may be heavier at one end than the other.

In a further embodiment, the first aspect of the invention is applied to twin sheet panels. For example, a twin sheet panel may be formed of a thermoplastics material the two sheets being joined together peripherally and possibly at at least one other discrete position, and in the cavity between the sheets filled with an expanded plastics material which may be injected into the cavity. The twin sheet panels may, for example, be formed as vehicle body panels, or parts of other components of vehicle bodies, such as bonnets.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of a bull bar in accordance with the first aspect of the present invention;

Figure 2 shows a cross-section along line 2-2 of Figure 1;

Figure 3 shows a perspective view of a portion of the core encased in one of the horizontal bars of Figure 1;

Figures 4 and 5 show respectively a perspective view and an enlarged fragmentary sectional view of another bull bar in accordance with the present invention in which additional elements are incorporated in fixing the bull bar for use and the attachment of fittings thereto;

Figures 6 , 7 an 8 are enlarged fragmentary views showing different inserts which may be incorporated into, for example, a bull bar in accordance with the invention;

Figure 9 is a sectional view through a bull bar with wiring for an electric lamp;

Figure 10 is a fragmentary perspective view of part of yet another bull bar; Figure 11 shows a perspective view of a baton in accordance with the first aspect of the present invention;

Figure 12 shows a cross-section along line 12-12 of Figure 11;

Figure 13 shows a perspective view of a portion of the core of the baton; and

Figure 14 shows a cross-section through a panel also in accordance with the first aspect of the present invention.

The bull bar 2 shown in Figure 1 comprises a bar 4 formed into a continuous loop having a pair of parallel horizontal sections 6,8, connected at their ends by vertical sections 10,12. The bar 4 is supported by a pair of support brackets 14,16 attached to the rear of each horizontal section 6,8 and adapted to be secured to the chassis of a vehicle to which the bull bar 2 is to be attached.

As shown in Figure 2, the bar 4 comprises a first member 20 of expanded plastics material which entirely encases a second member 22. In this example, the second member 22 is made of ABS and effectively forms a core of the bar, and the first member 20 is made of an expanded integral skin foam having appropriate density and hardness.

The cross-section of the second member 22 in this embodiment is substantially W-shaped but it may be of another suitable shape. It comprises a pair of spaced central legs 24,26 joined at one end by a central web 28. The other end of each central leg 24,26 is connected to a respective outer leg 30,32 which extends a short distance substantially parallel to its respective central leg before flaring out perpendicularly away from that leg towards the outside of the bar.

The second member 22 is formed by a vacuum moulding process and in the course of this a flexing point 34 is formed in the member. In this example, the flexing point 34 is formed by changing the shape of the second member at a desired point.

An A-bar, or other protective bar, for a vehicle may be similarly formed as a composite structure of a first member of expanded plastics material and a vacuum formed second member.

In Figures 4 and 5 another bull bar is shown which is made in essentially the same manner as the bull bar just described but in which fixing brackets 36 are incorporated for mounting the bull bar for use, and also attachment brackets 38 for attachment of accessories to the bull bar, such as driving lamps 40 as shown. The fixing brackets 36 and attachment brackets 38, which may be of metal or suitable plastics material, are moulded into the bull bar as the second member is formed, so that they become integral parts of the bull bar structure. Anchorage portions 42 of the brackets are angled or joggled within the body of the bull bar, as shown in Figure 5, to enhance the security and rigidity of their attachment to the bull bar.

The bull bars described, and other comparably formed composite articles, may have inserts, which may again of metal or plastics material, included in them, as shown by way of example in Figures 6,7 and 8. In Figure 6 internally screw-threaded inserts 44 are moulded in place in the composite article for the attachment of another article or element 46 to the composite article by screws 47. Figure 7 shows inserts 48 moulded into two composite articles to provide anchorages for bolting the articles together, and Figure 8 shows two moulded-in inserts 50,52 which are also bolted together.

If desired, a wiring loom 54, Figure 9, may be moulded into a composite article in accordance with the present invention, such as one of the bull bars described, an A-bar or other protective part for a vehicle, for the supply of electrical power to one or more driving lamps 56 and/or other electrically powered accessories. The wiring loom 54 is moulded into the composite article as the article is formed.

A particular advantage of the present invention is that it enables the composite article to be readily made in various forms. In the case of a bull bar, A-bar and such for a vehicle the article can be made in different styles to suit the body shapes of different types or models of vehicles.

Graphical, informational or promotional matter, such as shown in Figure 10 at 58, may be introduced into the composite article as the first member is moulded onto the second member.

In one particular example of the bull bar the second member is produced from 6mm thick extruded recycled sheet ABS, having a specific gravity of 1.07, which is vacuum formed to the required shape in a vacuum forming machine having either a cast resin or aluminium tool. For some bull bars thinner sheet material may be used, for example 3mm or 4.5mm thick. After it has cooled to a rigid state the vacuum formed member is removed from the machine and trimmed as necessary to the required form. Apertures are also formed in the member. Trimming and the forming of the holes is preferably done automatically by robot but it may be done manually. The member is then placed, with any fixings and/or other inserts required to be included in the bull bar, in a temperature-controlled (about 30-35°) foam box tool of a mould. The tool, which may also be of cast resin or aluminium, is sprayed with a release agent and an in-mould coat which gives the subsequently formed first member good UV stability and enables it to be coloured. Next, a foam mixing machine delivers, in a pre-determined ratio, polyether and isocyanate polyurethane self-skinning foam, of 0.35 specific gravity, into the mould, either open or closed. The foam expands into the closed mould and foam box tool around the second member. The heated foam box tool assists in the curing of the material. After removal from the mould the composite article so formed is left to rest and finish curing for about four hours. Any flash on the cured composite article is removed. The article may be painted subsequently, if desired.

Figure 11 shows a baton 60 having a body 62 with an integral handle 64 towards one end projecting perpendicularly to the body. The baton is made of a bar which is similar in ^• some respect to the bar previously described.

The baton comprises a core 66 (the second member) , Figures 12 and 13, of substantially annular cross-section made of ABS surrounded by expanded polyurethane foam 68. The central cavity 70 within the core 66 is also filled with polyurethane foam.

The core 66, which is formed by vacuum moulding, is provided with a flexing point 72, Figure 13, positioned along the body of the core adjacent to the attachment with the handle portion. The flexing point 72 is provided in this case by a portion of the core having a reduced external diameter compared with that at other parts of the core's body. The wall thickness of the core along the flexing point is maintained constant with that at other parts of the core's body.

Figure 14 shows a cross-section through a twin sheet panel 74. The panel 74 is formed from a pair of spaced sheets of thermoplastics 76,78 the second member, formed, for example, using the twin sheet forming process. At an edge 80 of the panel the sheets 76,78 come together and are fused together during the forming process. The sheets are also fused together at an intermediate joint 82 in the panel.

The cavity between the two sheets is injected with an expanded plastics material, the first member, in this case polyurethane foam 84.

A twin sheet panel such as this may be formed as a body panel, for example a wing or safety skirt, of a vehicle to offer increased impact protection, or it may form part of a vehicle body component, such as a leading edge portion of a bonnet.

Claims (31)

1. A composite article comprising a first member and a second member integrally joined together with one member containing the other, or substantially so, the first member being of an expanded plastics material and the second member being of a denser material having generally greater strength characteristics than the material of the first member such that the composite article has overall an impact absorbing strength substantially greater than that of the first member.

2. A composite article according to claim 1 in which the first member is of a polyurethane foam.

3. A composite article according to claim 1 or claim 2 in which the first member contains, or substantially contains, the second member.

4. A composite article according to claim 3 in which the first member is an integral skin foam.

5. A composite article according to any preceding claim in which the second member is of a thermoplastics material.

6. A composite article according to claim 5 in which the thermoplastics material is ABS.

7. A composite article according to claim 5 or claim 6 in which the second member is vacuum formed to the required shape.

8. - A composite article according to claim 3 or claim 4, or any of claims 5 to 7 as dependent from claim 3 or claim , in which the second member forms a core of the article.

9. A composite article according to claim 8 in which the second member is of substantially annular cross-section.

10. A composite article according to claim 9 in which the interior of the second member is filled with polyurethane foam.

11. A composite article according to any preceding claim in which at least one additional element is incorporated as the article is formed thereby to be an integral part of the structure of the article.

12. A composite article according to claim 11 in which the additional element is for fixing the article for use or for the attachment to the article of another item.

13. A composite article according to claim 11 in which the additional element is a wiring loom.

14. A composite article according to any preceding claim in which a point of weakness or flexing is formed about which the article is designed to bend or deform under impact.

15. A composite article according to claim 14 in which the point of weakness or flexing is formed by a localised reduction of cross-sectional thickness of the article.

16. A composite article according to any preceding claim which is substantially in the form of a bar.

17. A composite article according to claim 16 as dependant from any of claim 3,4,8,9 or 10 or as dependant from claim 3 and any of claims 5,6,7 or 11 to 15, in which the second member is in the form of an elastically deformable core element covered by the first member.

18. A composite article according to claim 17 which is in the form of a protective bar for a vehicle.

19. A composite article according to claim 17 which is in the form of a bull bar adapted for attachment to a vehicle.

20. A composite article according to claim 17 which is in the form of a baton.

21. A composite article according to claim 20 in which the baton comprises a body and a side handle, the second member extending through the body and side handle and being entirely contained by the first member.

22. A composite article according to claim 21 and claim 15 in which the point of flexing is formed in the body adjacent to the side handle.

23. A composite article according to any of claims 1 to 15 which is of substantially sheet form comprising spaced sheets peripherally joined together which form the second member and contain the first member.

24. A composite article according to claim 23 in which the first member is polyurethane foam.

25. A composite article according to claim 23 or claim 24 in which the spaced sheets are joined together at at least one intermediate discrete position.

26. A method of manufacturing a composite article as claimed in any of claims 3,4,8,9 or 10, or in claim 3 and any of claims 5,6,7 or 11 to 15, or in any of claims 17 to 22, comprising the steps of:

(a) pre-forming the second member;

(b) arranging the pre-formed second member in a mould, and

(c) injecting an expanded plastics material into the mould to form the first member which surrounds the second member.

27. A method according to claim 26 in which the second member is encased by the first member.

28. A composite article substantially as described herein with reference to Figures 1 to 3 of the accompanying drawings.

29. A composite article substantially as described herein with reference to Figures 4 and 5, or any of Figures 6 to 10, of the accompanying drawings.

30. A composite article substantially as described herein with reference to Figures 11 to 13 of the accompanying drawings.

31. A composite article substantially as described herein with reference to Figure 14 of the accompanying drawings.