WO2001085409A1

WO2001085409A1 - Corrugated wood product, method of manufacturing thereof and wooden structure

Info

Publication number: WO2001085409A1
Application number: PCT/FI2001/000404
Authority: WO
Inventors: Antero Salakari
Original assignee: Pyhäjoen Puu Oy
Priority date: 2000-04-28
Filing date: 2001-04-26
Publication date: 2001-11-15
Also published as: FI20001012A0; FI20001012A; FI110359B; AU2001258440A1

Abstract

The invention relates to a corrugated wood product, a method for its manufacture, and a wood structure. The corrugated wood product according to the invention comprises at least one first corrugated shingle (1) and at least one second corrugated shingle (2), which are fitted so as to follow each other, in substantially the same orientation, and one on top of the other in a sandwich style so that between them there is an adhesive layer (3) joining the shingles to each other.

Description

Corrugated wood product, method of manufacturing thereof and wooden structure

The present invention relates to the wood product according to the preamble of Claim 1, the wood structure according to Claim 10, and the method according to Claim 14 for the manufacture of a corrugated wooden sheet.

The simplest way of making sheet-like products of wood is the making of shingles. Conventionally shingles have been used for the illumination of rooms and later as covering for the roofs and walls of buildings. Shingle products have the characteristic that they become warped both during manufacture and when drying. Respectively, their characteristics also include easy bendability.

The earliest shingles were short, but recently a method has been developed for the production of long shingles (for example, FI 98282). A long shingle is obtained by planing over the entire length of a log. Such a product can be produced without wood being wasted in the form of chips or sawdust. At the same time it makes possible the manufacture of thin wood products the manufacture of which by sawing and planing would cause excessive losses of material. In the method described in Finnish patent 98282, the veneers planed from wood thus have the length of the raw timber and their thickness is approximately 0.1 - 2 mm, preferably 2 - 10 mm.

In a competition, "Wood of Finland," which was published in Finland in 1999, there was introduced a product comprising two corrugated veneers glued together crosswise. The price of such a specialized product is high, for the turning of the veneer for plywood is quite expensive. On the other hand, crosswise veneer in plywood tends to relatively easily shear under stress.

In the long shingle described, the wood fibers have their original orientation and the shingle thus has good bending flexure and bending resistance in the longitudinal direction, but especially poor in the transverse direction. For this reason, from wood veneers there is typically manufactured plywood in which several plies in between are crosswise and the plies are bound together usually with an adhesive film made up of an adhesive softening under heat and a paper impregnated with the adhesive. The heat-softening adhesive usually hardens later, i.e. bridges, under the same heat. The object of the present invention is to eliminate the problems associated with the prior art and to provide an entirely novel product made from wood and a method for manufacturing it.

The invention is based on the unexpected observation that by placing two long shingles one on top of the other so that between them is arranged an adhesive layer, by forming this arrangement, and by allowing the adhesive layer to harden, a corrugated wood product retaining its shape well is obtained.

More precisely, the product according to the invention is characterized in what is stated in the characterizing part of Claim 1.

The wood structure according to the invention is characterized in what is stated in the characterizing part of Claim 10.

The method according to the invention is characterized in what is stated in the characterizing part of Claim 14.

A number of considerable advantages are gained through the invention. The method for producing the present wood product is simple and effective. When thin veneers having the length of the timber are made by planing from raw timber, no losses of material are incurred. Compared with turning veneer for plywood, the manufacture of shingles to be used in the invention is more economical. On the other hand, the handling of thin veneers is light and does not require special equipment. The making of molds required in the inven- tion is moderately easy and economical, and thus the individual making of molds for each intended use of the corrugated product is profitable.

Sound insulation of buildings has long been a problem without an inexpensive solution. The technique of general attenuation of vibration is based on a law of physics, the variables being the mass and the attenuator, and a sound of a precisely certain frequency is attenu- ated with the correct ratio of these. Footfall sounds have been one of the problems most difficult to solve. The structure according to the present invention has at least two different elastic moduli: the resilience of the corrugated structure and the elasticity of the uncompressed wood material. If a suitable adhesive is used, the product has even a third different elastic modulus, namely, the elasticity of the adhesive. Furthermore, if the shingles are of different types of wood, a larger number of various attenuation factors and acoustic attenuation variants are obtained.

The wood product according to the present invention provides a more elastic and more yielding structure than, for example, plywood. The structure of plywood is compressed using rather high pressure, the material is often hard wood, and the structure is cross- laminated. A more elastic material distributes the mechanical stress over a larger area, and local stress peaks are not accumulated in the structure.

When the structure is part of the interior of a building, the original beautiful grain of the wood is visible, and it can be accentuated, for example, by moistening and brushing or by some other corresponding method.

The invention is described below with a detailed specification, and reference is also made to drawings, wherein

Figure 1 depicts a side elevation of a corrugated wood product according to the invention, Figure 2 depicts the structure of the floor surfacing of a building,

Figure 3 depicts a wood product wherein the corrugations are parallel to the longitudinal orientation of the shingle, and

Figure 4 depicts an I-beam the web of which comprises a corrugated wood product.

In the context of the present invention, by "shingle" is meant thin, typically approximately 0.1 - 50 mm, preferably approximately 0.5 - 20 mm and especially preferably 1 - 10 mm thick, pieces made from wood by, for example, planing, chamfering, or otherwise cutting. Most preferably the shingles are long, equal to the entire length of the raw timber, but their length can be optimized so as to be suitable in each given situation, Most typically the shingle length is thus at minimum approximately 5 m, preferably 8 - 15 m. The terms "wood veneer" or "glued product" have also been used for the shingles. The term "long shingle" is used in particular to describe a case in which the length of the shingle is substantially equal to the length of the raw timber.

By "corrugated" wood product is meant that the product has at least one corrugation. The corrugations are typically arranged so that the ridges of the corrugations are at an angle of at least 10°, preferably approximately 45 - 90°, and specifically approximately 90°, to the longitudinal orientation of the shingle, but the corrugations may also be substantially parallel to the longitudinal orientation of the shingle. The height of the corrugations and the distance between the corrugation ridges varies according to the intended use of the wood product. Typically the height of the corrugation is approx. 0.1 - 50 cm, preferably approximately 1 - 20 cm, and specifically approximately 1 - 10 cm. The distance between the corrugation ridges may vary very widely, thus their distance may be, for example, 1 - 200 cm, preferably 1 - 100 cm, and specifically approximately 2 - 10 cm.

Typically the corrugation pattern is substantially regular but, for example, in light fixture or interior applications it is conceivable that the height of the corrugations, the distance between the corrugation ridges or the angle of the corrugation ridges to the longitudinal orientation of the shingle varies within a shingle.

The corrugated wood product according to the invention comprises at least two shingles 1, 2 which have been formed into a corrugated shape, are placed one on top of the other in at least substantially the same orientation so as to fit each other, and are attached to each other by means of an adhesive layer 3 (see Figure 1).

The corrugated wood product is produced by placing at least two shingles one on top of the other in at least substantially the same orientation, with an adhesive layer arranged between them. The shingles are pressed together, and the structure is at the same time formed so that at least one corrugation is produced in it, preferably relative to the longitudinal orientation of the shingle. Optionally the product may also be heated during the forming. After the adhesive layer has hardened, the product is removed from the molds. The corrugated wood product corrugated in this manner retains its shape well.

The wood fibers in both or all of the shingles of the corrugated wood product according to the invention are arranged in substantially the same orientation. Most preferably the shingles are attached together so that the lower surface given to the shingle during the planing, in other words the surface that rises along the bevel of the blade, is attached with an adhesive against another shingle, preferably against the corresponding surface of the other shingle. The shingle may be, for example, of birch, pine, spruce, aspen, alder, oak, maple, linden, elm, or ash. Preferably the shingle is of birch. According to a first preferred embodiment of the invention, the two shingles described above are selected so that they are of different species of wood.

The adhesive layer is either an adhesive as such or a paper or a fabric or a fiber net saturated with an adhesive, or a membrane, such as an aluminum foil, to which adhesive has been applied. By means of the saturated paper or the like the adhesive can be distributed uniformly over the surface of the shingle.

The adhesive used is preferably any known wood glue, such as melamine, urea and phenol formaldehyde glues. According to a second preferred embodiment of the invention, the adhesive used is a polyurethane glue, especially preferably a single-component polyurethane glue which receives the -OH groups required for its hardening from the water present in the wood and which foams during the hardening. Thus there is obtained a corrugated wood product that has at least three different elastic moduli as footfall insulation for a building. First there is the resilience of the corrugated structure itself, second the elasticity of the uncompressed wood material and third the elasticity of the adhesive.

Another preferable adhesive is polyvinyl alcohol, in particular when the shingles are suitably dry. Polyvinyl alcohol provides very strong adhesion, for its viscosity rises to an immense level after water has left it.

Also suitable for use as the adhesive is, for example, any polyethylene plastic (PE-LD, PE- LLD, PE-MD or PE-HD) or polypropylene plastic. In this case, gluing the shingles together is carried out by melting the plastic between the shingles, whereafter the piece is formed, and cooled.

According to a third preferred embodiment of the invention, a paper or tissue impregnated with an adhesive is used in the adhesive layer. This is advantageous specifically in terms of the cohesion of the product, because in this case the tissue or the like receives loads in the transverse direction. This also makes it possible to place many shingles in parallel on both sides of the glued joint. A procedure such as this is often preferable, because it enables a wider wood structure to be produced at the same time, the structure comprising, placed in parallel, several pairs of shingles with an adhesive layer between them. On the other hand, such an arrangement makes it possible to make a wood structure of a desired size, comprising corrugated wood products.

It is possible to add a layer of adhesive or a tissue (e.g. cloth) or paper treated with an ad- hesive, or a membrane, e.g. an aluminum foil, to which an adhesive has been applied, also on the other flat surface of the shingle, that is the one which is not pressed against the other shingle. Either one or both of the shingles of a pair of shingles can be treated in this manner. Especially when the completed wood product is used under a floor surface in order to attenuate footfall sounds, it is advantageous to wax or coat with a plastic membrane those parts of the completed structure that touch one another. This treatment is preferably carried out before the assembling of the structure. Such a procedure attenuates creaking.

The shingles with an adhesive layer between them are pressed using molds so that from both above and below the pair of shingles is subjected to a force that gives the shingles a corrugated shape. Typically there is a mold with the desired corrugated pattern both above and below the pair of shingles. Usually the upper mold is pressed against a stationary lower mold; it is also possible to press the molds together from both sides or press the lower mold towards the upper mold, in which case the upper mold remains stationary.

According to a fourth embodiment of the invention, a previously prepared corrugated structure is used as the lower mold. In this case a new product is always pressed on top of a large, sufficiently rigid storage stack. Thus, separate handling of the storage stack is no more necessary; it can be packaged and sent to the customer for further treatment.

Typically, but not necessarily, heat is utilized during the forming. A typical temperature used during the forming is approximately 140 - 160 °C.

It is also possible to corrugate several shingles at a time by placing, for example, four plies one on top of the other, with an adhesive layer in each space between the shingles. They are pressed and formed until the adhesive has hardened. The shaped shingles are preferably treated in the conventional manner with fire-damping chemicals, such as borax, or by other known fire-damping materials. Fire-damping materials can also be added to the glues used in the adhesive layer.

Corrugated wood products according to the invention may be arranged so that they, or the wood structures made from them, are suited for several purposes.

Thus, according to a fifth embodiment of the invention, one or several corrugated wood products are arranged one on top of another so that the corrugations of the sheets are staggered, in which case gaps are left between the corrugations. It is also possible to saw out of the corrugated wood product narrower products parallel to the orientation of the principal dimension of the structure and place these one on top of another, in the manner described above, either instead of or in addition to the said corrugated wood products. Such a structure is preferably used in lighting fixtures so that the source of light or sources of light are behind the product. Another option is to use the structure as a sound attenuator.

According to a sixth embodiment of the invention, corrugations are combined crosswise, whereby a three-dimensional cellular structure is obtained. In other words, one or more corrugated wood products are placed one on top of another so that the ridges of the corrugations of the wood products are crosswise.

According to a seventh preferred embodiment of the invention, the three-dimensional cellular structure described above is made from very thin and long shavings, in which case corrugations are combined crosswise, as described above. A structure such as this absorbs impact energy well.

According to an eight embodiment of the invention, the shingles are corrugated strongly so that the corrugations are high and, preferably, narrow. A strongly corrugated product according to the invention can be cut by sawing between the corrugation ridges so that half- corrugations are obtained. These are preferably glued to grooves ground on the inside surfaces of a continuous sheet blank, whereby a somewhat resilient but, nevertheless, rigid sheet structure is obtained. According to a ninth preferred embodiment of the invention, the wood product is corrugated so that the corrugation or corrugations are parallel to the longitudinal orientation of the shingle. In this case the corrugations are preferably quite low and wide. Figure 3 depicts a corrugated wood structure according to this embodiment. In the option shown in the figure there is an adhesive layer 33 arranged between the first shingle 31 and the second shingle 32. If the corrugation is, as in Figure 3, at least substantially parallel to the longitudinal orientation of the shingle, it is advantageous to place many pairs of shingles adjacently and to coat also the outermost surfaces 34, 35 of the shingles with paper, fabric or the like, coated or saturated with an adhesive.

The corrugated wood product is in general suitable for use as such, or two or more corrugated wood products can be combined to form a wood structure. The combining is most typically carried out by using an adhesive layer, but, for example, nails, rivets or stitches can also be used for the attaching.

Below is a list of purposes for which corrugated wood products or wood structures made from them can be used:

1. As a footfall-sound-attenuating element below the floor surface in a building (see also Figure 2). In Figure 2 the corrugated wood product 1 according to the invention is placed between the floor surface 12 and the floor components, such as blocks 13. A hard- board 14 is preferably placed to reinforce the seam between the floor components 13.

2. As a sound-attenuating component in wall or ceiling structures.

3. Under the floor surface in a building as a site for cables and water pipes.

4. As a binding corrugation between the lower surface and the coating surface, whereby a sandwich structure is obtained. In this case the corrugation is placed upright between the boards. The corrugations may also be assembled one on top of the other, with a suitable phase difference, to form a wall surface (cf. the fifth embodiment of the invention above), which serves as a provider of light and/or as an acoustic element in walls or ceilings. Such acoustic boards may be either attached to the wall or ceiling structure or they may be separately suspended. 5. As a partition wall or corresponding separating wall in offices, shops and the like. The separating wall may be made up of one or more corrugated wood products. The corrugated wood product or a component assembled from them stands substantially supported by its own profile.

6. In light fixtures and/or as a protective trough for piping and the like, in which case the corrugations in the wood product are preferably in the orientation of the shingle. The corrugated wood sheet is suitably transparent to light, and so it is also as such excellent for decorative lighting.

7. A corrugated wood product the corrugation of which remains constant with the help of a glued structure can, when raised into an upright position, be caused also to serve as a stiffener for a plate structure, in which case a cellular structure can be produced with the help of the corrugations. Such a cellular structure can advantageously be used as an intermediate floor in a wood-structured house, and, furthermore, footfall sound attenuation produced by corrugation in another direction can be combined with it. Such resilient structures are also advantageous in, for example, earthquakes, to attenuate even large vibrations.

8. A laminate structure made from the corrugated wood product may also serve as an ecological outer facing structure of a building. In this case it is advisable to treat the laminate structure so that it will not decay and, on the other hand, to see to it that the structure is flame-proofed if the building has a chimney.

9. From the corrugated wood product there are obtained web connectors for beams and trusses which have in the axial direction more torsional rigidity than has an I-beam, and thus less buckling tendency. The corrugated wood product thus makes a firm joint structure possible. Thus the corrugated wood product 41 is suitable for being used in the manner shown in Figure 4, for example, as an isthmus between the lower part and the upper part of a beam or a connecting plate 42, 43.

10. The three-dimensional cellular structure according to the sixth embodiment of the invention can be used, for example, for the following purposes: i) As a bio-filter for the purification and aeration of water. The wood material provides a natural substrate for microbial growth. On the other hand, in the cellular structure the surface area per unit volume is large. ii) As fillers in, for example, technical applications wherein, for example, the contact between a gas and a liquid is promoted by means of pieces having a large surface area per unit volume. iii) Under water for the growing of young fish or crayfish. iv) On building surfaces as sound-attenuating elements. For this purpose, elements of the desired depth are preferably sawn out of a three-dimensional structure.

11. The three-dimensional cellular structure according to the seventh preferred embodiment of the invention serves as a good impact-energy-absorbing element and thus as a good packaging material, for example, for instruments and electronic equipment. It can also be used as the bottom of transport boxes, for example, in the transportation of fruit and the like, in which case the fruit is not damaged by impacts when the boxes are being moved.

Claims

Claims:

1. A corrugated wood product, characterized in that it comprises at least one first shingle (1) formed into a corrugated shape and at least one second shingle (2) formed into a corrugated shape, the shingles being arranged so as to fit one another, in substantially the same orientation and one on top of the other in a sandwich style so that there is between them an adhesive layer (3) joining the shingles together.

2. The wood product according to Claim 1, characterized in that the fibers of the original wood of the first shingle (1) and the second shingle (2) are arranged so as to be mutually in substantially the same orientation.

3. The wood product according to Claim 1 or 2, characterized in that of at least one shingle (1, 2) the surface which has risen along the bevel of the blade during the planing of the shingle is arranged against the adhesive layer (3).

4. The wood product according to any of Claims 1 - 3, characterized in that the corrugations of the wood product are at an angle of at least 10° to the longitudinal orientation of the shingles (1, 2).

5. The wood product according to any of Claims 1 - 4, characterized in that the adhesive layer (3) comprises an adhesive, a paper, fabric or other tissue or net saturated with an adhesive, or a membrane to which an adhesive has been applied.

6. The wood product according to any of the preceding claims, characterized in that that surface of at least one shingle (1, 2) which is on the side reverse to the side against the other shingle (1, 2) is coated with an adhesive, a paper, fabric or other tissue or net saturated with an adhesive, or a membrane to which an adhesive has been applied.

7. The wood product according to any of Claims 1 - 5, characterized in that that surface of at least one shingle (1, 2) which is on the side reverse to the surface against the other shingle is waxed or coated with a plastic membrane.

8. The wood product according to any of the preceding claims, characterized in that it comprises at least two pairs made up of a first shingle (1) and a second shingle (2), the said shingles being arranged so that their surfaces having the largest surface area are side by side.

9. The wood product according to any of the preceding claims, characterized in that it comprises at least one third shingle formed into a corrugated shape, arranged against the top shingle in the stack formed by the preceding shingles in a sandwich style, in at least substantially the same orientation, so that there is an adhesive layer between the planar surfaces of the top shingle in the stack and the third shingle.

10. A wood structure, characterized in that it comprises at least two wood products according to any of Claims 1 - 9.

11. The wood structure according to Claim 10, characterized in that it comprises one or more wood products according to any of Claims 1 - 9, the wood product having been sawn between the corrugation ridges into separate pieces having the shape of a half-corrugation, and the ends of the said pieces are placed into grooves ground in the part between the top sheet and the bottom sheet and been attached to them by gluing, whereby a strong lattice structure is obtained.

12. The wood structure according to Claim 10, characterized in that it comprises at least two wood products according to any of Claims 1 - 9, arranged one on top of another so that the ridges of the corrugations of the wood products are crosswise.

13. The wood structure according to Claim 10, characterized in that it comprises at least two wood products according to any of Claims 1 - 9 arranged one on top of another so that the corrugations of the wood products are staggered.

14. A method for producing a corrugated wood product, characterized in that - an adhesive layer (3) is arranged on at least one planar surface of at least one first shingle (1), at least one other shingle (2) is placed against the planar surface of the first shingle, in substantially the same orientation, so that the adhesive layer (3) is left between the shingles, and the product is corrugated by subjecting it from above and/or below to forces which produce a corrugated shape, until the adhesive layer has hardened.

15. The method according to Claim 14, characterized in that in the forming a mold is used above or below the pair of shingles made up of the first shingle (1) and the second shingle (2).

16. The method according to Claim 15, characterized in that one or more previously corrugated wood products are used as the lower mold for a pair of shingles.

17. The method according to any of Claims 14 - 16, characterized in that against the topmost surface of the stack made up of preceding corrugated shingles there is placed the planar surface of at least one third shingle in at least substantially the same orientation, and an adhesive layer is arranged between these surfaces.