GB2092948A - Veneer laminated wooden tubes - Google Patents

Abstract

Veneers of wood, of various thickness, are wrapped helically to produce a continuous tube. The species of wood from which the veneers are cut and the method of cutting used, the number of veneers, the internal and external tube diameters and the adhesives used may all be varied; the manufacturing process may include the incorporation of preservatives, reinforcing fibres, coatings and composite materials. The resulting product will enable the tube to be used as columns, struts, ties, beams or bracing components in structural applications. The tube may also be used for non-structural applications to which it may be suited, such as containers or units requiring a pleasing aesthetic appeal. <IMAGE>

Description

SPECIFICATION Veneer laminated wooden tubes Traditionally it has been accepted that where solid timber is used for structural applications, as columns, ties, struts, beams or bracings, the cross section of the members, or components making up a member, were rectangular or square.

In recent years the introduction of timber based board materials has influenced the timber designer to develop structural components using a composite of these board materials and solid timber to form ply web beams. This has helped to offer timber as an economic alternative to competitive materials.

Comparison of competing materials such as steel, concrete and timber shows that in solid rectangular or square form, timber exhibits the best strength to weight ratio. With the advent of shaped steel or concrete members, with I or tubular cross sections as a result of rolling or extrusion processes, timber has been relegated in its competitiveness.

The development of veneer laminated wooden tube will offer a product competitive to those already available.

The product The development of plywood has proved the advantage of cross laminating of veneers. Timber has a large variation in strength values between the planes parallel and perpendicular to the grain. The cross laminations enable the weaker aspects to be reinforced and strengthened by the stronger.

By wrapping veneers around a central mandril, it is possible to produce a tube that is effectively a continuous sheet of circular plywood with an indistinguishable and integrated seam along its length.

The manufacture of veneer laminated wooden tubes has to be considered from the basic principle and the variations that may be applied.

Basic principle of manufacture First a wood veneer, cut to an appropriate width, is wrapped around a steel mandril at a suitable angle to enable the veneers to provide a butt edge joint, thus providing an inner wall. (See Figure 1.) A second wood veneer is wrapped around the first (See Figure 2.) using an adhesive between the veneers to bond them together. The rotation of wrap of this veneer may follow the same direction as the first layer or can be applied in a counter direction to provide a cross lamination effect.

Subsequent wood veneers are wrapped in a similar process as the second veneer to provide a tube with a unidirectional layering of veneers on a counter cross laminated tube, (See Figure 3.) each layer being bonded to its adjacent layer to provide a rigid structure. The number of veneers laminated in this method will be decided by the requirements of its ultimate use and will thus determine the wall thickness of the tube.

Variations of manufacturing material and process To provide a variety of tubes that will be suitable for a number of end uses it is possible to incorporate within the basic manufacturing process variability of both the materials and the process used.

The basic wood veneer may be obtained from any one of the many species of timber available that will enable a technique of slicing or peeling to be used to obtain veneers of suitable quality for the manufacturing process employed, the thickness of the veneer being determined by the end use. The adhesive used to bond the two adjacent veneers together will vary by virtue of strength and durability required of the end product. Such adhesive will be selected from those currently available and may range from the less durable animal glues to the more sophisticated formaldihydes that will provide a water and boil proof resistant quality.

The manufacturing process may also include a form of preservation treatment that will provide a resistance to natural destroying agents; that is fungal attack, decay or insect attack. It may also be suited for resistance to damage by exposure to fire orwater. These treatments may be applied at the time the veneers are prepared for manufacture into the tubes or after the process has been completed.

Such treatment may be achieved using liquids and silicons by vacuum or natural impregnation, with salts, by diffusion, or by the use of plastics or urea compounds to provide a more stabilizing process through impregnation.

The appearance or strength properties of the tube may be enhanced with the inclusion of coatings or fibrous materials, other than wood, during the manufacturing process. The coating can be in the form of paints, varnishes, pigmented or clear finishes, glass fibre or carbon fibre. The paints, varnishes, pigmented or clear finishes may be designed either as a purely cosmetic finish or to provide resistance to abrasion or damage from the action or interaction of any associated materials or components. They may also provide resistance from the action or interaction of any naturally occurring atmospheric components or pollutants. These could occur due to the action of physical factors such as light or temperature.

The inclusion of fibrous materials as internal or external coatings in the form of glass fibre or carbon fibre, together with their associated matrix substances, may be desirous to improve the strength characteristics. They may be applied as individual filaments, clumped strands, woven or unidirectional mats and may be situated between the veneer layers, externally or on the original mandril in any direction deemed necessary relative to the axis of the length of the tube to provide the desired end product.

The steel mandril on which the tube is formed may vary in diameter to suit the end use to which the tube is to be put, thus altering the inside diameter of the tube accordingly. Having determined the inside diameter and established it by the selection of the mandril the outside diameter of the tube will be determined by the number and thickness of the veneer in combination with the thickness of the glueline between veneer layers. Utilization The utilization of the tubes manufactured in accordance with the methods described will vary and reflect the material used and construction processes used. The tube may be used for structural frameworks either for internal or external applications and such structures may be wholly wooden or partially composed of the wooden tubes providing a composite structure.

The tube, being manufactured from a nonconductive material, will provide a framework that will offer a high level of resistance to electrical conductivity when compared with traditional materials employed in similar situations. In addition to the application of the tube to structural applications it may also be required to carry materials, as a container. It will be desirous to ensure that when used in such a manner the adhesion of the contents, whether free flowing or as an attachment to the internal surface should not allow any detriment to the fabrication processes of the tube.

To enable the lengths of tubes to be joined together to form a framework it will be possibie to use a system of inserts, made from a suitable material that will fit into the ends of the tubes and enable the inserts to be connected to each other using a system of tension cables, rods or adhesives.

Alternatively it may be desirable to use external connectors that will clamp firmly around the outside of the tube at any point along its length. Such connectors may be jointed together or may be capable of locating two or more lengths of tube within the single coupling, thus providing a multiple connector.

The securing of inserts or connectors will be achieved using adhesives, rivets screws or any other mechanical fastening that will not detract from the inherent strength ofthetube provided by the manufacturing processes described or its variations.

Claims (17)

1. A method of manufacturing wooden tubes by the process of adhering together the adjacent surfaces of wood veneers wrapped helically at any angle, layer upon layer, to form a cylinder of length and wall thickness suitable for its ultimate use.

2. A method as in Claim 1 in which the wood veneers may be cut by slicing or peeling techniques from any one or more species of timber suitable for the end use of the fabricated tube.

3. A method as in Claim 1 in which the adhesive used to bond the adjacent veneers will be chosen from those adhesives that will provide a strong and durable tube to suitthe end use.

4. A method as in Claim 1 in which the inside diameter of the tube will be determined in accordance with the use to which it will be put.

5. A method as in Claim 1 in which the number of veneers wrapped layer on layer will determine the wall thickness of the tube, the number being selected to suit the use to which it will be put and the outside diameter varying accordingly.

6. A method as in Claim 1 in which the veneers may be pre- or post-treated with preservative mate rials to provide a resistance to fungal attack and decay or insect attack.

7. A method as in Claim 6 to provide a resistance to fire.

8. A method as in Claim 6 to provide a resistance to moisture penetration, including both liquid treatments and more permanent stabilisation systems.

9. The tube manufactured in accordance with any combinations of the above or later claims for use to create fabricated structures that are required to withstand forces within the capability of the materials being used. Such structures or frameworks may be external or internal and may be either wholly or partially composed of the wooden tubes.

10. The tube as in Claim 9 will provide components that will display a high resistance to electrical conductivity by comparison with similar components made from metals.

11. The tube as in Claim 9 will provide a compo next that may be used in situtations that require such lightweight tubes to carry materials or components within or attached to the inside surface without detriment to the fabrication of the tube.

12. The tube as in Claim 9 may be given internal or external coatings of paints, varnishes or other pigmented or clear finishes.

13. The tube as in Claim 9 may be given internal or external coatings of fibrous materials together with their associated matrix substances.

14. The tube as in Claim 13 may separately or additionally incorporate fibrous materials between the wood veneer layers with the intention of providing additional strength.

15. Systems using inserts of any material into the ends of the tubes that will enable the components to be formed into frameworks.

16. Systems using external connectors surrounding the tubes that will enable the components to be formed into frameworks. Such external connectors may also be fastened to each other.

17. Systems as in Claim 15 and 16 using adhesives, rivets, screws or any mechanical fastening to secure the inserts or external connectors in position.