WO2002090679A1

WO2002090679A1 - Method and device for making a timber joint

Info

Publication number: WO2002090679A1
Application number: PCT/FI2002/000378
Authority: WO
Inventors: Esko Huolman
Original assignee: Esko Huolman
Priority date: 2001-05-04
Filing date: 2002-05-03
Publication date: 2002-11-14
Also published as: FI20010938A0

Abstract

The present invention relates to a method and device (20) for making a timber joint, preferably an interlocking corner. Such a timber joint comprises hewn or planed logs (1) joined together by an edge joint. Indentations (7, 8) and notches (11) are arranged on the top, bottom and side surfaces (2, 3, 9, 10) of the logs joined together to enable the logs to be arranged crosswise, at the same time providing a longitudinal contact surface between the superimposed logs. In the method of the invention, the notches (11) on the side surfaces (9, 10) of the log are made by pressing the opposing side surfaces of the log with a device (20) essentially perpendicular to the side surfaces. By adjusting the pressing force (F), it is possible to affect the depth of the notches.

Description

METHOD AND DEVICE FOR MAKING A TIMBER JOINT

FIELD OF THE INVENTION

[0001] The present invention relates to a method according to the preamble of claim 1 for making a timber joint. The invention also relates to a device a ccording to the p reamble of claim 5 for making s uch a timber j oint.

This type of a timber joint is used especially in building holiday homes and cold and semi-cold buildings, which are all made of what is known as a light log.

BACKGROUND OF THE INVENTION

[0002] It can be said that throughout the ages, log houses have been made by joining logs together at the corners of the building by using different edge joints. To prevent wind and rain from entering the structures, a joint called a n i nterlocking corner i s m ost commonly u sed. This type of a j oint i s formed by logs hewn, planed, milled or sawed on four sides and arranged together at their joining point. This joint produces a rather solid and tight edge joint.

[0003] Even though this kind of an interlocking corner is traditionally easy to make, making it requires considerable professional skill, time and space. The making of such an edge joint becomes especially problematic when using light logs. Light logs are very thin hewn logs, often only 28 to 55 mm thick. Such light logs are often used to make rather simple buildings intended for summer or storage use. Working the side surfaces of a light log to make them even thinner at the joint would significantly weaken the strength of the structure and, consequently, the building, which is why an interlocking corner in its best form can seldom be used when building with light logs. There- fore, the corners of such buildings need to be separately sealed by lathing, for instance. Another alternative is naturally to accept the leaks in the corners of the building. This is less significant in storage buildings, but habitable buildings require quite good sealing and, consequently, the sound isolation it entails.

[0004] On the other hand, woodworking methods are known, in which dampened or wet timber is worked by simultaneously pressing and drying. Timber worked like this has been used in the shipbuilding and furniture industries, for instance. Timber worked mechanically in this manner is returned at least partly to its original shape by re-dampening it, whereby the timber expands due to moisture. These types of arrangements are disclosed in pub- lished DE patent 336,517 and published NO patent 34,981. The known solu- tions include, however, a considerable number of difficult work stages that make the method virtually unusable, if the aim is to process large numbers of building components in an inexpensive manner. Such known methods are also not suited for use when installing a log frame at its final building site.

BRIEF DESCRIPTION OF THE INVENTION

[0005] It is an object of the present invention to substantially reduce the shortcomings caused by these drawbacks in the prior art. This way, a completely novel solution is provided, which also makes it possible to use interlocking corners when building with light logs. [0006] The object is achieved by the present timber joint method having the characteristics of the invention defined in the claims. More precisely, the method of the invention is primarily characterized by what is stated in the characterizing part of claim 1.

[0007] This kind of a timber joint is in turn produced using a device having the characteristics of the invention defined in the claims. More precisely, the device of the invention is primarily characterized by what is stated in the characterizing part of claim 5.

[0008] Preferred embodiments of the invention are disclosed in the dependent claims. [0009] The invention is based on the idea of utilizing the natural ability of wood to change shape and its resilience when making the joint, whereby an easily assembled, but at the same time tight and structurally sound edge joint is achieved.

[0010] The method of the invention for making a timber joint pro- vides several advantages. The hewing of the joint that earlier required several work stages can now be done with a few fast and simple work stages when using the present method, in which the required joint notch is pressed to the side surface of the log. However, this provides a strong and tight joint that due to the low pressed notch does not in any way weaken even a thin light log. [0011] By utilizing t he fast a nd s imple m ethod of the i nvention, a light log becomes a very inexpensive and good-quality standard log especially for dwellings intended for summer use. Because an edge joint made with the present method tightens with time, it efficiently prevents water, snow or sleet from entering the structures. Due to the completely novel sealing ability of this edge joint, a building made of light logs or a part of it can even be battened, insulated and coated to make a building fit for winter habitation. By utilizing the invention, it is possible to have both winter cold and warm spaces in one building.

[0012] By making the joint with the method of the invention by pressing the required low joint notches on the surfaces of the log also elimi- nates the shavings and sawdust created as a result of the mechanical working, such as planing, milling or hewing, of the log. This increases significantly the safety of the work environment and at the same time prevents the cleaning, storage and disposal costs caused by the shavings and sawdust created during the mechanical working. Pressing also produces a neater than usual joint, because it does not break the surface of the log.

[0013] When all joint notches of a light log are made by pressing, the only waste matter produced consists of smallish wood blocks. Due to their dust-free state, these blocks can easily be utilized in a boiler or fireplace, for instance. [0014] It has also been noted that by making the edge joint with the present method, the problems caused by the variations in the thickness of the log due to manufacturing tolerances are avoided. Thus a conventional joint notch of a light log is always made to size. Because the thickness of a light log does, however, vary due to planing tolerances from a millimetre to a few milli- metres, the joint notch must always be dimensioned according to the thickest log. This naturally produces more undesirable slots in the corners. When joint notches are also pressed to the side surfaces of the log with the present method for making a joint, the slots due to manufacturing tolerances will close with time. Pressing the notches of the side surfaces in such a manner that the bottoms of the notches are always at the same distance from each other will avoid any problems caused by the manufacturing tolerances of the log. At the same time, however, this ensures that the edge joint is easy to assemble and prevents the joint and the surface of the log from breaking when the joint is assembled. [0015] When the joints of the logs always fit correctly together, the assembly of the edge joints becomes significantly faster than before. Performed tests show that the method of the invention saves as much as 60% of work time in comparison with the traditional log working and building.

[0016] Because a tight interlocking corner can be made with less work and from a cheaper material, the achieved economic savings are considerable - as much as 50%, when comparing a structure made with the method of the invention with a corresponding structure made using a thicker log. When producing the joint, the wood detached from it comes off in large pieces that are easier to utilize as burning material in fireplaces or boilers, for instance.

[0017] Because the log needs less mechanical working than before, less workspace is also required - the joint notches of the log can, if necessary, even be made at the building site. The machines and devices required for pressing are also considerably less expensive than the machines and devices needed to mill the log, for instance.

[0018] Joints made according to the invention allow for the normal settling of a log due to drying. In spite of this, the achieved timber joint is structurally so strong that it is not necessary to strengthen the joint by nailing.

[0019] The device with which the present timber joint can be made also provides its user several advantages. The device can be made structurally simple and strong. Because the joint notches made in the log are quite low, a rather low-power power source is required to provide the necessary pressing power. This type of a power source can even be operated by conventional lighting current. Therefore, the device is easy to use anywhere. As the device is simple and small, it is easy to transport, and logs can be processed with very little effort at the building site. If no supply current is available at the building site, such a low-power device can use a conventional electric generator easily transportable by hand.

[0020] The use of the device is very simple due to the few work stages. In addition to the means for pressing joint notches to the sides of the log, cutting blades can be fitted to the device to further simplify the making of the joint. Such additional cutting blades namely make it possible to make the indentations on the top and bottom surfaces of the log. The wood blocks detached when making the indentations on the top and bottom surfaces of the log m ay t hen b e p artly d etached d uring t he p reparation s tage u sing p arallel saw cuts. On account of this preparation, detaching the wood block requires clearly less pressing force than detaching a wood block from an intact log, which, however, is fully possible. Detaching the wood blocks from the log by pressing improves significantly the structure of the joint notch and its edges, thus also improving the quality of the finished timber joint.

[0021] Logs not suited for processing with a small, simple device - such as logs that are knotty at the joint site - are easy to sort and use at another location where it is not necessary to work all their surfaces. [0022] Due to the present computer-controlled manufacturing lines, it is easy to automate the making of the joint notches of the present light log.

BRIEF DESCRIPTION OF THE FIGURES

[0023] The invention will be illustrated in the following by examining a few preferred embodiments according to the attached drawings, in which

Figure 1 is a schematic representation of an edge joint of the prior art,

Figure 2 shows how a log that has already been sawed on its top and bottom surfaces is provided with a side notch, Figure 3 is a schematic representation of an installation-ready light log that has been notched on all sides,

Figure 4 is a schematic horizontal projection of an edge joint built of logs notched with the method of the invention,

Figure 5 shows a side view of a device used in making at least the side-surface notches of the log, and

Figure 6 shows a second embodiment of the device used in pressing the log, the pressing tool of the device having cutting blades,

Figure 7 shows a section at A-A of a pressing tool of an embodiment of Figure 6, the pressing tool having a cutting blade that can be guided to the bottom edge of the wood block of the joint, and

Figure 8 shows a section at A-A of a pressing tool of a second embodiment of Figure 6, the pressing tool having a cutting blade that detaches the wood block completely from the log.

DETAILED DESCRIPTION OF A FEW PREFERRED EMBODIMENTS [0024] A few preferred embodiments of the method for making a timber joint and the device used in making it are described in the following with reference to the above-mentioned figures. The solutions comprise the structural parts marked in the figures with reference numerals and corresponding to the reference numerals used later in this description. [0025] Conventionally the interlocking corner of Figure 1 is produced in such a manner that crossing logs are cut on all four surfaces for instance by cutting notches in the log. By then arranging the logs crosswise at these cut notches, the desired edge joint is formed. This type of an edge joint is structurally tight enough to prevent air from flowing through the built corner - which is why the structure is also called a wind corner. If necessary, the joint is sealed up to obtain the best possible tightness. Making such a joint does not present a problem as long as the log is thick and notches of a desired depth can be cut into it without damage to the strength of log.

[0026] When building storage buildings or buildings mainly intended for summer use of thin logs, or light logs, it is, however, practically impossible to notch the vertical side surfaces of the logs. Notching the vertical surfaces of a thin log having a thickness of 28 to 55 m m in general would significantly weaken the strength of both the joint and the entire structure. Not making a wind corner would, however, lead to leaving repeating slots in the edge joint that extend through the entire wall structure and creating a draft that is in some cases unpleasant. In the worst case, water or snow can enter the structures through these slots during rain or snowfall.

[0027] The present method for making timber joints is especially suited for making joints of hewn or planed logs. The method is especially ad- vantageous when used in making an interlocking corner of a building made of light logs. Such logs are conventionally used in making holiday houses for summer use and cold or semi-cold storage buildings in particular.

[0028] A timber joint is achieved as shown in Figures 2 to 4 in such a manner that first saw cuts 4 and 5 are made in the conventional manner on the opposing top 2 and bottom surfaces 3 of the log 1 to be fitted into the joint. These saw cuts are opposing with respect to the log surfaces, perpendicular and parallel, and there are at least two cuts per surface. The section of the log remaining between these parallel saw cuts, a wood block 6, is detached to provide first opposing notches or indentations 7 and 8 on the top and bottom surfaces of the log. After this, the dry log being processed is placed in a device that provides by pressing parallel notches or indentations 11 on the piece between the notches, i.e. on the opposing side surfaces 9 and 10. These notches preferably narrow in a wedge-like manner towards the bottom of the notch. The notches are only 1 to 2 mm deep, most preferably 1.2 to 1.5 mm. [0029] The logs 1 of Figure 3 shaped in the above-mentioned manner are placed crosswise according to Figure 4, whereby the notches 7 and 8 and notches 11 join together like jigsaw puzzle pieces, enabling the top and bottom surfaces 2 and 3 of superimposed logs to join together. Due to the notches 11 on the side surfaces 9 and 10 of the log and extending from the surface level of the side surface to the log, the superimposed logs push into the notches of the crosswise log between them. The width of the notch defined by the saw cuts 4 and 5 is then smaller than the distance between the side surfaces 9 and 10 of the log, whereby a tight edge joint as shown in Figure 1 is achieved.

[0030] According to a specific embodiment, the bottoms of the notches 11 are arranged to be equidistant from each other. This way it is possible to compensate for the dimensional variances caused by the manufacturing tolerances of the log without having to work the notches 7 and 8 on the top and bottom surfaces.

[0031] A naturally dry log 1 or a log dried to room humidity that is worked by pressing according to the present method reverts with time at least partly to its original shape at the notches 11 on the side surfaces 9 and 10. Due to t he small changes of shape made i n the wood, this creeping of the wood towards its original shape takes place without external measures. This way, the bottom of the notch rising towards the original side surface level of the log meets during its change of shape the vertical surfaces of the saw cuts 4 and 5 in the notches 7 and/or 8 of the top surface 2 and/or bottom surface 3. The edge joint thus in a way intergrows and becomes tighter than before and at the same time strengthens and stiffens. Due to this reversing change of shape, the joint can be made without supporting nailing, whereby its strength becomes better and the required amount of work is substantially reduced. Because the notches on the top and bottom surfaces of the logs can due to the reversing change of shape be initially made fairly large, the edge joint is quick and simple to assemble, since it requires less force than usual to make the log notches settle in their interlocking positions. This also prevents the otherwise often occurring at least partial break of the joint. The fact that the notches of the side surfaces 9 and 10 do not require any kind of mechanical working of the log also makes making the joints easier than before. Hewing the joints produces l ess sawdust a nd c hips than before, which e ssentially i mproves work safety and reduces both the need for storage space for construction waste and the need for workspace. By increasing the pressing force it is also at the same time possible to increase the final non-reversible change of shape of the notch on the side surface of the log in that the grain of the wood is partly broken.

[0032] The pressed notch 11 is preferably shaped to narrow like a wedge in the downward direction in its position of use. This way when the joint dries and expands, it presses the interlocking corner tightly towards the ground beam of the building, thus stiffening the structure of the corner. This way it is possible to leave out the nailing or screw bar otherwise often used in the corner. The interlocking corner thus adjusts more naturally to the moisture conditions and its manufacturing costs are even more inexpensive.

[0033] Because the present method for making a joint produces a normal edge joint, it also allows the structures to settle in the usual manner. The edge joint is, however, sufficiently tight and no additional sealing in the form of stuffing or lathing is required.

[0034] By arranging essentially horizontal cutting blades 21 in the device 20 pressing the notches on the side surfaces 9 and 10 of the log 1 , the wood block 6 remaining between the saw cuts 4 and 5 made on the top 2 and bottom 3 surfaces of the log can be detached during the same work stage as the notches on the side surfaces are made. This both speeds up the making of the joint and improves its quality, because the bottoms of the notches on the top and bottom surfaces of the log become more even than usual. [0035] Figures 5 to 8 show one embodiment of the device 20 with which the notches 11 are provided on the side surfaces 9 and 10 of the log that are vertical in their position of use. The device comprises an essentially stiff body 22 from which a stopper 23 extends. This stopper has a first pressing surface 24 arranged on the side surface of the log. Further, a pressing means 25 movable towards the stopper and having a second pressing surface 26 is arranged to the body. The pressing surfaces are essentially parallel with each other on the side surfaces sides of the log. The movement of the pressing means is controlled by a mechanical, electric or pressure medium-operated operating unit (not shown) known per se, whereby a pressing force F is pro- vided on the opposite side surfaces of a log placed between the pressing means and the stopper. The pressing force produces the desired changes of shape o n the s ide s urfaces 9 a nd 1 0 of the l og. T he s ize of the c hange of shape, i.e. the depth of the notch 11 , can be adjusted by altering the pressing force of the operating unit. By increasing the pressing force, the final non- reversible change of shape of the notch on the side surface of the log is also increased.

[0036] The device 20 can also be equipped with a measuring device

27 that is arranged to adjust the distance between the pressing surfaces 24 and 26. This type of a measuring device makes it possible to ensure that the distance between the bottoms of the notches 11 is similar regardless of the thickness of the light log. In addition, the device preferably comprises a guide element that is arranged to set the pressing surfaces 23 and 24 at desired locations. The pressing surfaces are then aligned with the log through the saw cuts 4 and 5, for instance.

[0037] The operating unit controlling the pressing means 25 is a pressure medium-operated hydraulic cylinder, pneumatic cylinder or mechanical device, such as a spindle motor controlling a torsion bar. The operating unit adjusts both the size of the pressing force F directed to the side surface 9 and 10 of the log and the approach rate of the pressing surfaces. This type of an operating unit is preferably controlled with a lighting current-operated power source so as to enable its use in different environments. A joint should preferably be made at the building site so that the notches of the log are finished only during assembly. Therefore, the pressing device 20 should preferably be made so small that it can easily be transported to any building site.

[0038] The notches 11 produced on the side surfaces 9 and 10 of the log 1 can be adjusted in depth and in shape by selecting a desired shape for the pressing surface 24 and 26. The pressing surface, therefore, preferably comprises a wedge-like piece that produces a notch that narrows towards its bottom. T he shape of the pressing surface also helps avoid damage to the edge of the joint notch 11 and consequently, an unaesthetic joint. To prevent the edge from breaking, the outer edge of the pressing surface must be made sharp enough to cut the grain of the wood when entering the wood. In an alternative embodiment of the pressing surface, its outer edge is arranged to be round. When the surface of the log is pressed, the grain of the wood then bends without breaking towards the bottom of the joint notch, keeping the sur- face structure intact.

[0039] As shown in Figures 6 and 7, the pressing means 25 and/or stopper 23 can also be equipped with at least one cutting means 21 , such as a cutting b lade 28, w ith which t he w ood b locks 6 r emaining b etween t he s aw cuts 4 and 5 on the top 2 and bottom 3 surfaces of the log can be detached from the log. The cutting blade then presses into the side surface of the log when the log is pressed with the pressing means towards the stopper and a pressing means preferably equipped with a cutting blade in it. The length of the cutting blade is selected in such a m anner that the wood block can be detached without the cutting blade touching the pressing surface pressing the side surface on the opposite side of the log. The cutting blade surface oriented towards the surface of the joint p referably comprises a surface structure 29 finishing the surface of the wood. This surface structure is for instance a coarse or file-like surface.

[0040] A second embodiment of the device 20 comprises cutting means 21 for making the notch 7 and/or 8 in the log. As shown in Figure 8, the pressing surface then preferably comprises at least one essentially U-shaped means having in addition to the cutting blade two essentially parallel vertical blades 30 for making notches replacing the saw cuts 4 and 5. To provide the opposing notches 7 and 8 in the log, the cutting means are arranged in the pressing means 24 and stopper 23 opposite each other. Alternatively both cut- ting means are arranged in the same pressing means or stopper.

[0041] The stopper 23 in the device 20 can naturally be arranged movable with respect to the body 22 as shown in Figure 6, in which case an operating unit (not shown) is arranged to control the stopper. This way, both the stopper and the pressing means 25 are arranged to move towards the log 1 placed in the device from its opposing sides.

[0042] It is to be understood that the foregoing description and the related figures are only intended to illustrate the present invention. The invention is thus not restricted only to the above description or the embodiment disclosed in the claims, but it will be apparent to those skilled in the art that many variations and modifications may be made to the present invention without departing from the inventive idea defined in the attached claims.

[0043] The description therefore mainly examines the making of an edge joint with light logs. However, nothing prevents the utilization of such a method when making edge joints using thicker hewn logs 1. The method pro- vides similar savings in work time and saw dust and chip handling regardless of the thickness of the log. The device 20 used in the method, with which the necessary notches 11 are made on the side surfaces 9 and 10 of the log 1 , can be utilized when building with light logs and thicker logs. The pressing force of the device only needs to be increased as necessary and the structures made firmer.

[0044] The pressing of the log 1 can also be arranged to be done with two different pressing devices. In such a case, the notches 11 are pre- pressed into the side surfaces of the log at the factory or work yard and the wood blocks 6 on the top and bottom surfaces 2 and 3 of the log are detached at the same time. This work can be done with a strong pressing device that can be used to notch both light logs and thicker hewn logs. During the final installation, the notches 11 on the side surfaces of the logs are finished, if necessary, with a low-power, preferably lighting current-operated device 20. This way, installation is fast and no extra wood blocks 6 accumulate at the building site. The pressing of the log is also easier than usual due to the ready-made pattern. This type of a procedure is especially advantageous when building largish buildings or any such buildings that cannot be transported assembled to the building site. The procedure is also especially well suited for making and installing small saunas in flats.

Claims

1. A method for making a timber joint, the joint comprising hewn or planed logs (1) joined together by an edge joint, with notches and indentations (7,8, 11 ) arranged on the top, bottom and side surfaces (2, 3, 9, 10) of the logs being joined together so that the logs can be arranged crosswise, at the same time providing a longitudinal contact surface between the superimposing logs, characterized in that the notches (11) on the opposing side surfaces (9, 10) of the log (1) are provided by pressing the side surfaces of the essentially dry log with a pressing tool (20) substantially perpendicular to the side surfaces a predefined distance, whereby adjusting the pressing force affects the depth of the provided notch (11) with respect to the surface of the log and provides the notching without chipping the log and weakening its strength, wood blocks (6) are detached from the log to form opposite notches

(7, 8) extending to the top and bottom surfaces (2, 3) of the log, the logs are arranged crosswise on top of each other, the notches in the crosswise logs pushing first into each other and further into the pressed notches, the pressed notch (11 ) being arranged to creep towards the original side surface of the log, thus tightening the joint between the logs.

2. A method as claimed in claim ^characterized in that the notches (7, 8) on the top and bottom surfaces (2, 3) of the log (1) are made by sawing on each opposite surface at least two cuts (4, 5) perpendicular to them and by removing the wood blocks (6) between the saw cuts, the log pieces being detached with at least one cutting blade (28) in the pressing tool (20) preferably during the pressing of the side surfaces.

3. A method as claimed in claim ^characterized in that the notches (7, 8) on the top and bottom surfaces (2, 3) of the log (1) are made by removing the wood blocks (6) from the log by pressing the side surface of the log with the at least one cutting blade (28) in the pressing tool (20) and with a cutting means (21) made up of two parallel vertical blades (30) preferably during the pressing of the side surfaces.

4. A method as claimed in claim 1, 2 or 3, characterized in that the pressing is done during the making of the timber joint.

5. A device (20) for making the notches required in a timber joint, characterized in that the device (20) comprises a pressing tool equipped with two essentially parallel pressing surfaces (24, 26), the pressing surfaces being essentially parallel to the side surfaces

(9, 10) of the log (1) and arranged to approach each other by means of an operating unit to press a log arranged between them, thus making a notch (11) on the side surfaces of the log, the notch having a predefined depth.

6. A device (20) as claimed in claim 5, characterized in that the depth of the notch pressed on the side surfaces of the log is 1 to 2 mm.

7. A device (20) as claimed in claim 5 or 6, characterized in that the pressing surfaces (24, 26) comprise pieces that narrow essentially like a wedge towards the log (1) arranged in the device (20) to achieve a notch (11) narrowing towards its bottom on the side surfaces (9, 10) of the log.

8. A device (20) as claimed in any one of claims 5 to 7, character i z e d in that at least one pressure medium-operated operating unit running by a pressure pump controlled by an electric motor is arranged to control the movement of the pressing surfaces (24, 26).

9. A device (20) as claimed in any one of claims 5 to 7, characterized in that at least one electric spindle motor is arranged to control the movement of the pressing surfaces (24, 26), a screw bar in the spindle motor being arranged to adjust the rate of movement and pressing force of the pressing surface directed to the log (1).

10. A device (20) as claimed in any one of claims 5 to 9, c h a r - acterized in that the device (20) comprises one essentially stationary stopper (23) equipped with a pressing surface (24) and a second pressing surface (26) arranged movable towards it, to achieve pressing force on the opposing sides of the log.