WO2002009929A1

WO2002009929A1 - Methods and means for reinforcing elongate cores

Info

Publication number: WO2002009929A1
Application number: PCT/AU2001/000918
Authority: WO
Inventors: Kevin Francis Fitzpatrick
Original assignee: Polychem Australia Pty Ltd
Priority date: 2000-07-27
Filing date: 2001-07-27
Publication date: 2002-02-07
Also published as: AUPQ905000A0

Abstract

A method for reinforcing core materials which are made of relatively low density material and which would otherwise be quite easy to break, the reinforcing including providing one or more elongate slots or grooves in the material which are filled with a settable resin material to provide the reinforcement. The method is particularly suited for the manufacture of surfboards, sailboards and similar watercraft.

Description

METHODS AND MEANS FOR REINFORCING ELONGATE CORES

TECHNICAL FIELD This invention relates to methods and means for reinforcing core materials and has particular application to methods and means of reinforcing low density cores used in structures such as watercraft, planks, beams and the like.

BACKGROUND ART There are many uses for lightweight core materials such as foamed polystyrenes. Foamed polyutheranes are used for insulation, as fillers and in packaging to protect goods.

The foams are universally used as core materials for recreational watercraft such as surfboards, boogie boards, sailboards, windsurfers and the like. In the watercraft industry foams are generally covered with plastics or fibregiass materials to protect the core and for decorative purposes.

Fibreglassing however does not add a great deal to the strength of the structures. As a result measures are taken to reinforce structures based on foamed polyutherane cores.

Surfboard manufacturers for example reinforce boards with elongate, (usually wooden) stringers. Without reinforcing the boards would be too weak for the purpose that they are intended.

The manufacturing process involves splitting a pre-made foam core into elongate half sections, gluing the half sections to either side of the stringer, and clamping the half sections whilst the glue is curing.

A protective fibregiass coating is then applied to the assembled core.

Fibregiass coatings are applied in progressive layers over a period of hours.

This is a time consuming manufacturing technique, and the cost of traditionally manufactured surfboards is relatively high. It is an object of the present invention to provide a method of reinforcing elongate core structures which will provide the structures with greater resistance to impact forces and loading at a substantially reduced manufacturing cost. Further objectives and advantages of the present invention will become apparent from the ensuing description which it is given by way of example.

According to the present invention there is provided a method of reinforcing an elongate structure the method comprising forming the structure in a parent material, cutting elongate slots in the parent material and filling the slots with a settable cellular material to reinforce the structure.

The parent material may be expanded polystyrene, polyutherane, a PVC foam, or a low density foaming polyutherane elastomer.

The settable material may be a resin. The structure can form the core of a watercraft.

The structure can be a plank or beam.

The structure may be coated with a protective and/or decorative material.

The coating can be a composite material such as fibregiass. The coating can be a plastics coating.

According to a further aspect of the present invention there is provided a structure formed from a low density parent material and reinforced by a settable material applied to elongate slots in the structure.

The elongate openings can be lengthwise and/or crosswise. According to a further aspect of the present invention there is provided a hull structure for a watercraft such as a surf or sailboard having at least one elongate reinforcing "vein" in at least one surface thereof.

The elongate veins may be formed from cellular resin of reduced density in the range of 50kg per cubic meter to 800kg per cubic meter. Suitable materials may be low density polyesters, epoxy resins, or vinyl esters. DESCRIPTION OF THE DRAWINGS Aspects of the present invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is diagrammatic side view of a surfboard and rider, and Figure 2 is cross sectional drawing of a conventionally reinforced surfboard, and

Figure 3 is a cross sectional view of a sur board manufactured in accordance with one aspect of the present invention, and

Figures 4 and 5 are sectional views of a surfboard having reinforcing slots therein, and

Figures 6 and 7 are a cross-sectional views of a surfboard showing top and bottom veins of settable material placed in slots the veins being joined by dowels, pins, rods or the like, and

Figure 8 is a plan view of a surfboard having a plurality of reinforcing veins therein, and

Figure 9 is a cross sectional view of a plank or beam structure manufactured in accordance with the present invention.

With respect to the drawings Figure 1 shows a typical situation of a surfboard rider 1 surfing a wave 2 on a surfboard 3. As each wave 2 is ridden out the underlying ocean floor 4 is potentially a hazard to the rider and his board, particularly if the board tilts forward and the front of the surfboard impacts with the ocean floor below.

In these circumstances it is quite common for a surfboard to sustain a break, the break usually occurring at a distance S, approximately two thirds from the rear end of the board.

Breakage's can also occur in other circumstances for example where the board is unattended in shallow water and is pounded by large waves.

Typical conventionally constructed surfboard as illustrated by Figure 2 comprises a foam core 5 typically a polystyrene foam, a central reinforcing stringer, typically a wooden stringer, and a coating 7, typically a fibregiass coating. In general the stringers 6 are relatively thin strips of timber.

The size of the stringers 6 is usually based on a compromise between adding strength and keeping weight down.

Stringers having webs and flanges would enhance the structural integrity of watercraft such as surfboards however conventional manufacturing techniques as described previously and/or the costs of improving structural integrity in this way is cost prohibitive.

There are a number of resins available which bond particularly well with foamed polyutheranes and the present invention proposes use of such resins to provide reinforcing at least along the lengthwise axis of an elongate core.

Illustrations of such vein structures are shown by Figures 3 to 9 of the drawings and generally indicated by arrow 8.

The structures can be manufactured in many different configurations.

Finishing coatings may be in materials other than fibregiass, for example paints, resins and the like.

As illustrated by Figures 3 through to 8 of the drawings the present invention provides an alternative to conventional watercraft manufacturing techniques notably in that there is no need to split and rejoin the core materials 5 in order to reinforce the structures.

Longitudinal reinforcing may be created by providing an elongate slots 9 in surfaces of the core material 5, filling the slots with a resin material, allowing the resin infill to cure, inverting the core 5 and providing a second vein of reinforcing material. The reinforcing material may or may not be homogenous throughout the depth of the core.

In Figure 5 the reinforcing veins overlap.

In Figures 6 and 7 in possible alternative structures the veins 10 do not overlap and the reinforcing veins are joined by pins, dowels or the like 11.

Whilst it is envisaged that 1 single reinforcing vein along the central longitudinal axis of the core material 5 would be sufficient to reinforce the hull of a surfboard it may be that a plurality of reinforcing veins both in a longitudinal and intersecting horizontal axis (as is illustrated by Figure 8) will further enhance the strength of such structures.

The method of the present invention may also be used to reinforce other elongate structures such as planks.

The plank or beam illustrated by figure comprises a core material 5, and a plurality of reinforcing veins 12.

The beam may be provided with a coating or skin, in the form of a shrink wrap film, a paint or other form of plastics coating, e.g. Polyutherane or a aromatic or aliphatic polyurea having a hardness of between shore A60 and shore D80 and an elongation of between 250 and 5 percent.

The present invention has the advantage of considerably cutting down the labour time in the manufacture of structures such as surfboards. The boards will have increased loading and impact resistance in terms of flexibility.

Aspects of the present invention have been described by way of example only and it would appreciated that modifications and additions thereto may be made without departing from the spirit or scope thereof.

Claims

Claims 6

1. A method of reinforcing an elongate structure the method comprising forming the structure in a parent material, cutting elongate slots in a parent material and filling the slots with a suitable settable material to reinforce the structure.

2. The method of claim 1 wherein the parent material is selected from the group consisting of polystyrene, expanded polystyrene, polyurethane, polyvinylchloride, polyvinylchloride foam, polyurethane elastomer and low density foaming polyurethane elastomer.

3. The method of claim 2, wherein the acceptable material is a resin.

4. An article of manufacture formed of a low density material and which is reinforced by a settable material applied to elongate slots in the structure.

5. The article of claim 4 comprising a watercraft.

6. The article of claim 4,wherein the settable material comprises a resin.

7. The article of claim 6 wherein the resin is selected from the group consisting of polyester resins, low density polyester resins, epoxy resins and vinyl esters.

8. The article of claim 4 comprising a coating.