WO1996007802A1

WO1996007802A1 - A timber element and method for manufacturing the same

Info

Publication number: WO1996007802A1
Application number: PCT/FI1995/000386
Authority: WO
Inventors: Tuomo Poutanen
Original assignee: Honkarakenne Oy
Priority date: 1994-07-05
Filing date: 1995-07-04
Publication date: 1996-03-14
Also published as: FI96710B; FI96710C; FI943212A; FI943212A0

Abstract

The invention relates to a timber element (1) and a method for manufacturing the same. The timber element is designed for building log houses and similar log structures. The element is provided with a number of essentially vertical narrow, long and deep grooves (4) running along the lengthwise direction of the timber element. Among other things, these grooves improve the heat insulation capacity of the timber element.

Description

A timber element and method for manufacturing the same

The invention relates to a timber element defined in the introductory part ot patent claims 1 and 2.

The invention also relates to a method according to the introductory part of patent claim 15 for manufacturing the said timber element.

In the prior art there is known, from the Norwegian patent publication NO- 173,068, a timber log designed for building, provided with vertical cavities arranged in one or several rows in the lengthwise direction of the log. The cavities in adjacent rows are arranged in an overlapping fashion, so that the cavities and the tongues in between the cavities alternate, when the log is observed on the cross-sectional level. When observing this type of timber, it is particularly pointed out that it is asymmetrical in cross-section, and that the timber cross-sections in the lengthwise direction thereof are essentially similar. It is a drawback that the timber tends to twist owing to this asymmetry. Another drawback is that the cavities remain visible at both ends of the log. This is a remarkable drawback from the esthetic point of view.

In the prior art there is known, from the Swedish patent publication SE- 396,432, a timber element, in the middle whereof there is arranged a vertical slot along the lengthwise direction of the timber element, which slot is filled with heat insulation material.

In the prior art there is also known, from the US patent application 4,344,263, a timber element, on the vertical middle area whereof there is arranged one or more relatively wide slots in the lengthwise direction of the timber element. Each slot is most advantageously filled with a suitable heat insulation material, such as polyurethane.

It is a drawback in the known timber elements that the cavities or slots are large and wide. In most cases the cavities and slots are meant to be filled with heat insulation material, and what is more with such heat insulation material which does not breathe and thus destroys the natural good moisture resistance properties of the wood material. It is also pointed out that in such large and wide cavities or slots, when they are open spaces unfilled with heat insulation material, air has easy access to circulate particularly via the seams in between the individual timber elements, so that both the theoretical and calculatory increase in the heat insulation capacity brought about by means of the said timber elements is lost, and in practice the heat insulation capacity deteriorates as compared to a similar massive whole wood timber element.

Another drawback with known timber elements is that they are difficult to realize as regards production technique. Particularly the working of the cavities used in the above mentioned Norwegian patent is laborious and requires a lot of energy.

It is an object of the present invention to introduce a new timber element which has clearly better heat insulation capacities than a similar massive timber element with the same measures, but which in appearance resembles an ordinary timber element. It is a particular object of the invention to introduce a production-technically economical air-insulated timber element. Yet another object of the invention is to introduce a method for manufacturing the said timber element.

The timber element of the invention is characterized by the novel features enlisted in the independent patent claim.

The method for manufacturing the timber element of the invention is characterized by the novel features enlisted in patent claim 15.

The timber element according to the invention, meant for building log houses or similar log constructions, is provided with a number of essentially vertical cavity zones that run along the lengthwise direction of the timber element.

According to the invention, the cavity zone of each timber element includes at least one narrow, long and deep groove, and in between the said cavity zones, in the lengthwise direction of the timber element, there are zones of wood material.

According to an alternative embodiment of the invention, the timber element is formed in known fashion of at least two tightly attached, advantageously glued timber element parts, each of these parts comprising a cavity zone provided with at least one narrow, long and deep groove, and in between the said parts, in the lengthwise direction of the timber element, there are located zones of wood material.

Here a narrow and long groove means a groove where the width to length ratio is for instance 1 : 100 or less. This kind of groove can be made in the timber element by using a circular saw or another similar tool. A deep groove here is a groove where the width to depth ratio is for instance 1 : 10 or less. Generally the groove is arranged in the lengthwise direction to extend at least halfway up the height of the timber element, or, if the timber element is compiled of several timber element parts glued together, to at least halfway up the height of the timber element part. It is also possible that the grooves extend all the way through the timber element or the timber element part.

In the method according to the invention for manufacftiring a timber element meant for building log houses or similar constructions, in the timber element blank there is provided a number of vertical, adjacent narrow and long grooves, which extend deep into the timber element bland and/or through the same, and in between the said grooves, there are left wood material zones, whereafter the timber element blank is processed in known fashion into a timber element. The timber element blank can be a blank containing the whole timber element, or a blank contaύiing only one timber element part.

It is an advantage of the invention that the heat insulation capacity of the timber element is improved. The narrow grooves and particularly the large number of adjacent grooves effectively prevents the heat from conducting in between the vertical outer surfaces of the timber element. Another advantage of the invention is that the natural good features of the timber element, such as good breathing capacity and pleasant appearance, are retained in addition to the improved heat insulation capacity.

Yet another advantage of the invention is that the grooves are narrow, with a width of 5 mm at the most, and relatively long, advantageously 600-1,200 mm at the minimum, arranged in the lengthwise direction of the timber element. It is fairly simple to provide the timber element with such grooves; the grooves can be made with a circular saw, for example all adjacent grooves at the same time. Thus the production of the timber element according to the invention is simple and effective. In a preferred embodiment of the invention, each cavity zone of the timber element comprises a number of successive grooves, and a number of short wood material tongues - short with respect to the length - in between the grooves. The advantage of this embodiment is that the rigidity and holding strength of the timber element can thus be improved.

In another preferred embodiment of the invention, the grooves and wood material tongues of the cavity zone of the timber element are arranged so that the wood material tongues of adjacent cavity zones are set in an at least partly overlapping fashion with respect to each other in the lengthwise direction of the timber element. The locations of the wood material tongues alternate on the transversal plane of the timber element, and consequently it is an advantage of this preferred embodiment that the heat insulation capacity of the timber element improved with grooves is at least roughly equal within the grooved area. Another advantage of this embodiment is that the rigidity and holding strength of the timber element are improved owing to the provided wood material tongues.

In another preferred embodiment of the invention, the grooves and wood material tongues of the cavity zone of the timber element are arranged so that the wood material tongues of adjacent cavity zones are located in an essentially same wood tongue area in the transversal direction of the timber element. Now the wood tongue areas run through the timber element in an essentially perpendicular direction, and the wood tongue areas are arranged to follow each other at suitable distances in between. The advantage of this embodiment is that the timber element can be cut at the wood tongue areas, so that the cutting surface always resembles the respective cutting surface of a corresponding whole wood timber element. Thus the appearance of the timber element remains similar to a massive timber element also at the cross-cut surfaces. Another advantage of the wood material tongue areas is that they enforce the timber element, which thus remains rigid in spite of several adjacent cavity zones.

In another preferred embodiment of the invention, the adjacent cavity zones are arranged on the transversal plane of the timber element in the vertical middle area thereof, so that on the vertical sides of the timber element there is an essentially unbroken wood material layer having a width of at least 20 mm, advantageously 25-30 mm. With a round log element, these wood material layers at the sides are larger than the above said measure at least in their maximum width. It is an advantage of this embodiment that the grooves in the cavity zone and particularly their orifices located on the top and/or bottom surface of the timber element are effectively sealed while stacking the timber elements on top of each other. Now air is prevented from circulating through the grooves and the slots of the timber elements laid on top of each other and thus from niining the improved heat insulation capacity of the timber element. In this respect a particularly advantageous embodiment of the invention is a timber element where the grooves of adjacent cavity zones are directed symmetrically in an alternating fashion, from the bottom surface of the timber element or timber element part towards the top surface thereof and vice versa.

It is an advantage of the invention that the timber element is relatively light. It is clearly lighter than a whole wood timber element with corresponding outer measures. This is due to the fact that wood material is removed from the timber element of the invention at the grooves.

Another advantage of the invention is that the grooves can be arranged, advantageously machine-tooled, into a wet timber element blank. The grooves extend deep into the wood material (even through it), which means that at the drying stage the moisture is effectively removed from the wood material also as regards the heartwood, and consequently the drying time can be remarkably reduced.

The drying period can be shortened even by 30-40 % in comparison with the drying of a massive timber element blank. Yet another advantage is the fact that now the timber element blanks can in principle be dried in the same fashion as sawn goods. The drying time is defined mainly on the basis of the thickness of the unbroken wood material layers located on the vertical sides of the timber element blank; the drying time equals to that of sawn goods with nearly the same dimensions.

Moreover, it is advantage of the invention that sawdust is left as waste from working the grooves. The sawdust can then be for instance burned and its energy content recovered. Thus the energy used in working the grooves is in principle recovered when burning the sawdust. Yet another advantage of the invention is that the timber element sinks and twists less than a corresponding whole wood timber element. It is particularly pointed out that in the timber element according to the invention, where the grooves are arranged symmetrically, the transformations caused by twisting or grinding are slight. Thus the quality of the timber element is improved.

It is yet another advantage of the invention that the timber element does not split when drying like a massive whole wood element. It is pointed out that the vertical sides of the timber element of the invention, particularly those of an essentially symmetrical timber element, remain unsplit. This means that the quality of the timber element is improved in this respect, too.

The invention is explained in more detail below with reference to the appended drawings, wherein

figure 1 illustrates a timber element of the invention in perspective; figure 2 is a transversal section A- A of the timber element of figure 1; figure 3 is a lengthwise section B-B of the timber element of figure 1; figure 4 is a transversal section of another timber element according to the invention; figure 5 is a lengthwise section C-C of the timber element of figure 4; figure 6 is a transversal section of a third timber element according to the invention; figure 7 is a lengthwise section D-D of the timber element of figure 6; figure 8 is a transversal section of a fourth timber element according to the invention; figure 9a illustrates a fifth timber element according to the invention in perspective, seen obliquely from upwards; and figure 9b illustrates the same timber element as turned upside down, also in perspective; figure 10 is a transversal section E-E of the timber element of figure 9; figure 11 is a transversal section F-F of the timber element of figure 10; figure 12 is a top-view illustration of a sixth timber element according to the invention; figure 13 is a transversal section G-G of the timber element of figure 12; figure 14 illustrates a seventh timber element of the invention in perspective; and figure 15 is a transversal section H-H of the timber element of figure 14. The timber element according to the invention is meant to be used in the building of log houses, log frameworks and in general various log structures, where timber elements are stacked on top of each other and connected in order to form walls etc. In cross-section, the timber element can be round or quadrangular. The timber element can be made of one massive log, or it can be compiled by adhesion of several adjacent and or superimposed timber element parts.

In the timber element 1 according to the invention, as is apparent for instance from figures 1, 2 and 3, there is arranged a number of essentially vertical cavity zones 2, which run in the lengthwise direction of the timber element. In between the said cavity zones 2, there are provided corresponding vertical wood material zones 3 running in the lengthwise direction of the timber element. Both zones 2, 3 can be defined as areas that are at least roughly quadrangular in cross-section and extend through the timber element from top to bottom in the vertical direction and from end to end in the lengthwise direction.

In the first embodiment of the invention, figures 1, 2 and 3, the cavity zone 2 of each timber element 1 includes one narrow, long and deep groove 4. The grooves 4 of the cavity zones are arranged to extend from the top surface la of the timber element 1 downwards, to a small distance from the bottom surface lb. Now the grooves 4 extend from the top surface la of the timber element 1 to a slight distance from the bottom surface lb of the timber element, the said distance being for instance 1/5 of the height of the timber element. Now the unbroken bottom part 5 of the timber element 1 connects the vertical wood material zones 3. The grooves 4 of the timber element 1 are arranged symmetrically with respect to the central vertical plane of the timber element.

In another embodiment of the invention, figures 4 and 5, the cavity zone 2 of each timber element 1 comprises two narrow, long and deep grooves 6, 7. The first groove 6 of each cavity zone is arranged to extend from the top surface la of the timber element 1 downwards to the middle section of the timber element, and the second groove from the bottom surface lb of the timber element upwards to the middle section of the timber element. In between the grooves 6, 7, in the middle section of the timber element, there now remains a middle part 8 which interconnects the parts 9, 10 of the wood material zone 3 in between the cavity zones 2 and at the same time in between the grooves 6, 7. The grooves 6, 7 of this timber element 1 are arranged symmetrically with respect to the central vertical plane and the horizontal plane (i.e. with respect to both the top and bottom surfaces la, lb).

In a third embodiment of the invention, figures 6 and 7, the cavity zone 2 of each timber element 1 comprises a narrow, long and deep groove 11, 12. In this embodiment, the grooves in the adjacent cavity zones 2a, 2b separated by the wood material zones 3, are arranged so that in the first cavity zone 2a, the groove 11 is arranged to extend from the bottom surface lb of the timber element 1 upwards, to fairly near to the top surface la of the timber element, and in the second cavity zone 2b, the groove 12 is arranged to extend from the top surface la of the timber element 1 downwards, to fairly near the bottom surface lb of the timber element. This alternating groove arrangement is repeated throughout the timber element 1.

In the embodiment of figures 6 and 7, the grooves 11, 12 of the timber element 1 are arranged symmetrically in relation to the central vertical plane of the timber element and essentially symmetrically in relation to the top and bottom surfaces la, lb of the timber element (notice: it is still possible to have an odd number of grooves 11, 12). Moreover, the grooves 1 la, 1 lb located nearest to the side surfaces Id, lc of the timber element are most advantageously arranged to extend from the bottom surface lb upwards, towards the top surface la of the timber element. This is the most advantageous arrangement, because it effectively prevents the access of water possibly dripping from the top to the grooves nearest to the said side surfaces Id, lc. If water gets into the grooves, it rots the timber elements.

Figure 8 illustrates a fourth preferred embodiment of the invention. Here the timber element 13 is formed of timber element parts 13a, 13b, 13c glued on top of each other. Each timber element part 13a, 13b, 13c is provided with a number of essentially vertical cavity zones 14; 14a, 14b, 14c, which run along the lengthwise direction of the timber element part as well as of the timber element, and in between the said cavity zones there are provided, when seen in the transversal direction of the timber element, a number of corresponding vertical wood material zones 15; 15a, 15b, 15c, running along the lengthwise direction of the timber element part and the whole timber element. The cavity zones 14; 14a, 14b, 14c and the wood material zones 15; 15a, 15b, 15c are arranged in the superimposed timber element parts 13a, 13b, 13c most advantageously so that they are vertically aligned, as is clearly seen in figure 8. In this embodiment, the cavity zone 14; 14a, 14b, 14c of each timber element part 13a, 13b, 13c comprises one narrow, long and deep groove 16a, 17a; 16b, 17b; 16c, 17c, but there can also be two of them (cf. figure 4).

In the embodiment of figure 8, in the first adjacent cavity zones 14aι, 14a₂ of the first timber element part 13a, separated by the wood material zones 15a, the grooves 16aι, 17aι are arranged so that in the first cavity zone 14aι, the groove 16a, is made to extend from the bottom surface 13a₂ of the timber element part 13a upwards, to fairly near the top surface 13aj of the timber element part, and in the second cavity zone 14a₂ the groove 17aj is made to extend from the top surface 13aι of the timber element part 13a downwards, to fairly near the bottom surface 13a₂ of the timber element part 13a. In the adjacent first cavity zones 14bι, 14r>₂ of the second timber element part 13b, separated by the wood material zones 15b, the grooves 16bι, 17bι are arranged so that in the first cavity zone 14bι, the groove 16bι is made to extend from the top surface 13bι of the timber element part 13b downwards, to fairly near the bottom surface 13b₂ of the timber element part, and in the second cavity zone 14b₂ the groove 17bι is made to extend from the bottom surface 13b₂ of the timber element part 13b upwards, to fairly near the top surface 13bι of the timber element part 13b. In the third timber element part 13c, the grooves 16c; 16cι, 17c; 17c, of the cavity zones 14c; 14cι, 14c₂ are arranged in similar fashion as in the first timber element part. Thus the alternating groove system is repeated throughout all timber element parts 13a, 13b, 13c, as is apparent from figure 8. Now the grooves 16a, 17a; 16b, 17b; 16c, 17c of the timber element parts 13a, 13b, 13c are aligned at the border surfaces of the timber element parts and thus form uniform vertical grooves extending over the timber element parts.

The timber element 13 of figure 8 is symmetrical with respect to the grooves 16a, 17a; 16b, 17b; 16c, 17c in relation to the central vertical plane. Moreover, the timber element 13 is syrnmetrical with respect to the border surfaces of the timber element parts 13a, 13b, 13c. It is also pointed out that the grooves nearest to the side surfaces of the timber element 13 (such as 16a,, 17b], 17cι) are most advantageously arranged so that the in the topmost timber element part 13a the groove 16a; 16aι begins at the bottom surface 13a₂ of the timber element part 13a and is directed towards the top surface 13a!, and the same happens in corresponding fashion in the lowest timber element part 13c. This groove system corresponds to the groove system of the timber element 1 of figures 6 and 7, and has the same advantages: the access of water to the outermost grooves is prevented, as well as the successive rotting of the timber element.

In the timber element 13 of figure 8, the grooves 16, 17 of the timber element parts 13a, 13b, 13c are arranged in a certain way illustrated in the drawing. It is, however, clear, that the grooves of the timber element parts can be arranged in many different ways; groove alternatives applied for timber elements are illustrated for instance in figures 2, 4, 6, 9a, 9b, 10, 11, 12, 13, 14 and 15.

The timber element of figure 8 is formed of timber element parts 13a, 13b, 13c glued on top of each other. The timber element can also be formed of adjacently glued parts, in which case the adjacent parts (or at least those parts that belong to the middle area of the timber element) contain cavity zones and wood material zones, for instance according to the embodiments of figures 2, 4, 6, 9a, 9b, 10, 11, 12, 13, 14 and 15.

A fifth embodiment of the invention is illustrated in figures 9a, 9b, 10 and 11. In this embodiment, the cavity zone 2 of the timber element 1 comprises successive narrow and long grooves 18; 181, 182, 183; 19; 191, 192, 193, and in between the grooves wood material tongues 20; 201, 202; 21; 211, 212 which are short compared to the grooves. The said tongues are arranged so that the wood material tongues 20; 201, 202; 21; 211, 212 of adjacent cavity zones 2; 2a, 2b are located essentially in the same wood material tongue area 22; 221, 222 in the transversal direction of the timber element 1 or on the transversal plane thereof.

In this embodiment, figures 10 and 11, in the adjacent cavity zones 2a, 2b separated by the wood material zones 3, the grooves 18, 19 are arranged so that in the first cavity zone 2a, the groove 18 is arranged to extend from the top surface la of the timber element 1 downwards, to relatively near the bottom surface lb of the timber element, and in the second cavity zone 2b the groove 19 is arranged to extend from the bottom surface lb of the timber element 1 upwards, to relatively near the top surface la of the timber element. This alternating groove system is repeated throughout the timber element 1, as is seen in figure 10.

The grooves 18, 19 of the timber element 1, figure 10, are arranged symmetrically with respect to the central vertical plane of the timber element and essentially symmetrically with respect to the top and bottom surfaces la, lb of the timber element. It is, however, pointed out that there can be an odd number of grooves 18, 19. Moreover, the grooves 19a, 19b nearest to the side surfaces Id, le of the timber element are most advantageously arranged to extend from the bottom surface 16 of the timber element upwards towards the top surface la of the timber element. In this respect the groove system here is similar to those described above, for instance in the embodiments of figures 6 and 7.

The ratio of the length of the wood material tongues 20, 21 of the cavity zone 2; 2a, 2b to the lengths of the grooves 18, 19 in the lengthwise direction of the timber element 1 is advantageously of the order 1:5-1:15. The length of the wood material tongues 20, 21 of the cavity zone 2; 2a, 2b in the lengthwise direction of the timber element is of the order 10-15 cm, and respectively the length of the grooves 18, 19 in the lengthwise direction of the timber element is of the order 60-120 cm. This makes it easier to fit the timber element in wall constructions; it can be cut to measure at one of the wood material zones 22, so that the grooves 18, 19 are not visible on the cutting surface.

A sixth embodiment of the invention is illustrated in figures 12 and 13. Each cavity zone 2; 2a, 2b of the timber element 1 comprises, in similar fashion as in the previous embodiment of figures 9a, 9b, 10 and 11, successive narrow and long grooves 18; 181, 182, 183; 19; 191, 192, 193 and therebetween respective wood material tongues 20; 201, 202; 21 ; 211, 212 which are short compared to the length of the grooves. In between the cavity zones 2; 2a, 2b, there are left wood material zones 3. The adjacent grooves 18, 19 of adjacent cavity zones 2a, 2b are arranged to be directed in an alternating fashion from the bottom surface lb of the timber element towards the top surface la and vice versa. Now the cross-section G-G of the timber element 1 corresponds to the one illustrated in figure 13. In this embodiment, the grooves 18; 181, 182, 183; 19; 191, 192, 193 belonging to the cavity zone 2 of the timber element 1 as well as the wood material tongues 20, 21 are so arranged that the wood material tongues 20, 21 of adjacent cavity zones 2a, 2b are filled in an overlapping fashion with respect to each other in the transversal direction of the timber element 1. Now the wood material tongues 20, 21 do not constitute a uniform wood material tongue throughout the timber element 1, as in the embodiment of figures 9a, 9b, 10 and 11, but the wood material tongues 20, 21 overlap with the grooves 18, 19 of the cavity zones 2.

A seventh embodiment of the invention is illustrated in figures 14 and 15. In this embodiment, the cavity zone 2 of the timber element 1 comprises successive narrow and long grooves 23; 231, 232 and therebetween wood material tongues 24; 241, which are short compared to the grooves; the said tongues are arranged so that the wood material tongues 24 of adjacent cavity zones 2 are located essentially in the same wood material tongue are 25; 251 in the transversal direction or plane of the timber element 1. In this embodiment, the grooves 23 of the cavity zone 2 are arranged to pass through the timber element 1, from its bottom surface lb to its top surface la. Thus a wood material zone is 3 is left in between two cavity zones 2.

The timber element of the invention is generally manufactured so that a freshly cut log of wood is sawn or worked into a timber element blank, which is then dried and processed, for instance planed and/or milled, into final form to obtain a timber element suited for building. Alternatively the timber element blank can constitute a part of the final timber element, which part is, after drying and processing, most advantageously compiled by adhesion to constitute the timber element proper (cf. figure 8).

In the method of the invention for manufacturing a timber element, in the timber element blank there is arranged a number of vertical, adjacent narrow and long grooves 4, as was illustrated for instance in connection with figure 1 ; the said grooves 4 extend deep into the timber element blank and/or through it, and in between the said grooves, in the lengthwise direction of the timber element blank, there are left wood material zones 3, whereafter the timber element blank is processed, such as dried, planed and/or milled (and compiled by gluing) in known fashion into a timber element. This method for manufacturing a timber element is suited both for round and planed logs.

According to an advantageous method for manufacturing timber elements, the grooves are arranged, when observing the log on the horizontal plane, in the middle are of the timber element, as is illustrated for instance in figures 2, 4, 6 and 8.

According to another advantageous method for manufacturing timber elements, the grooves are arranged in the timber element blank essentially symmetrically with respect to the transversal and/or vertical plane of the timber element blank, as is seen for instance in the ready-made timber elements in figures 2, 4, 6 and 8.

Moreover, in an advantageous method for manufacturing timber elements, the grooves 4; 6, 7; 11, 12; 16, 17; 18, 19; 23 are sawn in the timber element blank.

The width of the grooves 4; 6, 7; 11, 12; 16, 17; 18, 19; 23 of the cavity zones 2; 14 of the timber element 1; 13 is 5 mm at maximum, advantageously 3.5-4.0 mm, even 1.0-3.0 mm. In between the cavity zones 2; 14 and the grooves, the width of the wood material zones 3; 15 placed in the lengthwise direction of the timber element 1; 13 is 10 mm at maximum, advantageously 5-8 mm.

The number of the adjacent cavity zones 2; 14 of the timber element 1; 13 is at least six, advantageously ten, even twelve or more. They are most advantageously arranged vertically and symmetrically on the transversal plane of the timber element.

The adjacent cavity zones 2; 14 of the timber element 1; 13 are on the transversal plane of the timber element 1 or timber element part 13a, 13b, 13c arranged in the middle area 25 thereof, so that on the sides lc, Id; 13d, 13e of the timber element 1 or element part 13, there is an essentially unbroken wood material layer 26, 27 (for instance figures 1 and 8) with a minimum width of 20 mm, advantageously 25-30 mm.

The grooves 4; 6, 7; 11, 12; 16, 17; 18, 19; 23 of the cavity zones 2; 14 of the timber element 1; 13 are advantageously arranged to begin and end at a slight distance, such as 5-15 cm, from the free end le, If of the timber element, as is illustrated in the drawings. When seen from the side, the grooves 4; 6, 7; 16, 17; 18, 19; 23 of the cavity zones 2; 14 of the timber element 1; 13 are at both ends provided with curved parts 28, as is apparent from figures 1, 4 and 7, for example. The grooves 4; 6, 7; 11, 12; 16, 17; 18, 19 are made in the timber element 1; 13 advantageously by means of one circular saw blade or several parallel circular saw blades, which blades are pressed to a suitable depth in the timber element. According to the form of these blades, both ends of the grooves 4; 6, 7; 11, 12; 16, 17; 18, 19 consequently obtain their curved form. Thus the ends of the timber element 1; 13 are left unbroken, so that for instance at a protruding log corner, the timber elements appear to be ordinary massive timber elements.

In the above specification, the invention is described mainly with reference to a few preferred embodiments, but it is naturally clear that the invention can be modified in many different ways within the scope of the inventional idea defined in the appended patent claims. For instance the timber elements illustrated in the appended drawings are essentially quadrangular in cross- section, but they can also be round or oval, or have some other geometrical shape.

Claims

1. A timber element (1) designed for building log houses or similar log structures, the said timber element (1) comprising several essentially vertical cavity zones (2) arranged to run in the lengthwise direction of the timber element, characterized in that each cavity zone (2) of the timber element (1) contains at least one narrow, long and deep groove (4; 6, 7; 11, 12; 18, 19; 23), and in between the said cavity zones (2), in the transversal direction of the timber element, there are provided wood material zones (3).

2. A timber element (13), designed for building log houses or similar log structures, the said timber element (13) comprising a number of essentially vertical cavity zones (14), arranged to run in the lengthwise direction of the timber element, characterized in that the timber element (13) is formed in known fashion of at least two tightly connected timber element parts (13a, 13b, 13c), and that each of these parts is provided with a cavity zone (14a, 14b, 14c) comprising at least one narrow, long and deep groove (16; 16a, 16b, 16c; 17; 17a, 17b, 17c); in between the said grooves, in the lengthwise direction of the timber element, there are placed wood material zones (15; 15a, 15b, 15c).

3. A timber element according to claim 1 or 2, characterized in that each cavity zone (2; 14) of the second part (13a, 13b, 13c) of the timber element (1; 13) comprises a number of successive long grooves (18; 181, 182; 19; 191, 192, 193) and therebetween a number of wood material tongues (20; 201, 202; 21 ; 211, 212) which are short compared to the length of the said grooves.

4. A timber element according to claim 3, characterized in that the grooves (18; 181, 182; 19; 191, 192, 193) and wood material tongues (20; 201, 202; 21; 211, 212) belonging to each cavity zone (2; 14) of the timber element (1; 13) or a part (13a, 13b, 13c) thereof are arranged so that the wood material tongues (20; 21; 201, 211; 202, 212) of adjacent cavity zones (2a, 2b) are arranged in an at least partly overlapping fashion with respect to each other in the transversal direction of the timber element (1) (figure 12).

5. A timber element according to claim 3, characterized in that the grooves (18; 181, 182; 19; 191, 192, 193) and wood material tongues (20; 201, 202; 21; 211, 212) belonging to the cavity zone (2, 14) of the timber element (1; 13) or a part (13a, 13b, 13c) thereof are arranged so that the wood material tongues (20; 21; 201, 211; 202; 212) of adjacent cavity zones (2a, 2b) are located on an essentially same wood material tongue area (22; 221, 222) in the transversal direction of the timber element (1) (figures 9a, 9b, 10, 11).

6. A timber element according to claim 3, 4 or 5, characterized in that the length of the wood material tongues (20, 21) of the cavity zone (2; 14) of the timber element (1; 13) or a part thereof (13a, 13b, 13c) in the direction of the timber element is of the order 10-15 cm, and respectively the length of the grooves (18, 19) in the lengthwise direction of the timber element is of the order 60-120 cm.

7. A timber element according to any of the preceding claims, characterized in that the width of the grooves (4; 6, 7; 11, 12; 16, 17; 18, 19; 23) of the cavity zones (2; 14) is 5 mm at maximum, advantageously 3.0-4.0 mm.

8. A timber element according to any of the preceding claims, characterized in that the width of the wood material zones (3; 15) located in between the cavity zones (2; 14) in the transversal direction of the timber element is 10 mm at maximum, advantageously 5-8 mm.

9. A timber element according to any of the preceding claims, characterized in that the number of adjacent cavity zones (2; 14) is at least six, advantageously ten, even twelve or more.

10. A timber element according to claim 9, characterized in that the adjacent cavity zones (2; 2a, 2b; 14) are on the transversal plane of the timber element arranged in the vertical middle section (10, 25) thereof, so that on the vertical sides (lc, Id) of the timber element (1; 13), there is an essentially unbroken wood material layer (11, 12) with a minimum thickness of 20 mm.

11. A timber element according to any of the preceding claims, characterized in that the grooves (4; 6, 7; 11, 12; 16, 17; 18, 19; 23) of the cavity zones (2; 14) are arranged in an essentially symmetrical fashion in the timber element (1) or a part (13a, 13b, 13c) thereof. 12. A timber element according to any of the preceding claims, characterized in that the grooves (11,

12; 16, 17; 18) of adjacent cavity zones (2; 2a, 2b; 14) are directed in an alternating fashion from the bottom surface (lb) of the timber element (1) or timber element part towards the top surface (la) and vice versa.

13. A timber element according to claim 12, characterized in that the grooves (11a, 1 lb; 16aι, 16cj) located nearest to the vertical sides (lc, Id) of the timber element (1) or part (13a, 13c) thereof are directed from the bottom surface (lb; 13a2) of the timber element (1) or part (13a, 13c) thereof towards the top surface (la; 13aι).

14. A timber element according to any of the preceding claims 1-10, characterized in that the grooves (23) of the cavity zone (2) are arranged to run through the timber element (1).

15. A method for manufacturing a timber element, designed for building log houses or similar log structures, characterized in that in a timber element blank, there is provided a number of adjacent vertical narrow and long grooves (4; 16, 17), which extend deep into the timber element blank and/or therethrough, and that in between the said grooves (4; 16, 17) in the lengthwise direction of the timber element blank, there are left wood material zones (3; 15), whereafter the timber element blank is processed in known fashion into a timber element.

16. A method according to claim 15, characterized in that the grooves (4; 16, 17) are arranged on the horizontal plane of the timber element in the middle area (10; 25) thereof.

17. A method according to claim 15 or 16, characterized in that the grooves (4; 16, 17) are arranged symmetrically in the timber element blank.

18. A method according to claim 15, 16 or 17, characterized in that the grooves (4; 16, 17) are sawn in the timber element blank.