Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27M—WORKING OF WOOD NOT PROVIDED FOR IN SUBCLASSES B27B - B27L; MANUFACTURE OF SPECIFIC WOODEN ARTICLES
  • B27M1/00—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching
  • B27M1/02—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching by compressing

Definitions

• the present invention relates to a method of compressing wood of the kind disclosed in the preamble of claim 1 , and a system to realise the method.
• the hardness of wood is a function of the density of the wood. This means that heavier arts of wood are harder than lighter arts of wood. This is true even within one and the same piece of wood.
• the density of the spring wood is about 1/3 of the density of the summer wood (-300 kg/m J and -900 kg/m J . respectively) for wood from needle-trees, such as pine and spruce, grown in Sweden. Transition wood between spring and summer wood is provided, and the density transition will therefore be continuous. However, the transition between summer and spring wood is abrupt.
• spring wood which comprises large air filled channels (lumen) in the cells, is the easiest to compress. These channels have thin cell walls, which can deform easily without damaging them.
• the summer wood has cells having thick walls with rather small lumen and can therefore not be compressed to a great extent before the cell walls are crushed or broken.
• FIG 1 illustrates a piece of wood treated with this kind of compression. This piece of wood has got a crush of a summer wood layer at A. A shear fracture between spring and summer wood, or in the spring wood, as shown at B, represents a common problem.
• the piece of wood shown in FIG 1 is cut such that its flat sides are parallel to a diametrical section through a log of wood.
• the annual rings lie essentially parallel to the flat sides, at least in the middle of the piece of wood since they are arcuate.
• Limbs in the wood have an essentially higher density (and hence hardness) than the rest of the piece of wood.
• the limb direction, and hence limb fibre direction lies practically radial in the tree trunk, and has a certain angle against the longitudinal direction of the tree trunk, most often 70° to 90°. If the limbs are to be compressed in their longitudinal direction, a strong force is required. This causes great cross-damages in the material, partly because of the limb as such and partly because of the cross grain around the limb. Solutions to this problem have been tried by establishing the compression power by means of relatively soft plates of rubber, which admit the hard limbs to be pressed into the plate of rubber and providing a proportionately even pressure on the wood surface. Thereby, isostatic compression provides the best compression result.
• An object with the invention is to provide a method and system, which remove the problems stated at the introductory part of this specification.
• Another object with the invention is to provide a method and system providing compressed, hard pieces of wood without splits and cross damages.
• Still another object with the invention is to provide a method and system providing compressed hard pieces of wood having an esthetical attractive surface structure.
• the invention thus relates to a method for providing a hard piece of wood using compression treatment in order to compress a disjoint timber of wood, which is characterised by a) preparing the piece of wood such that it comprises a piece of wood essentially having standing annular rings perpendicular to the flat sides of the piece of wood: b) placing the piece of wood between two plates, which have a fixedly provided position in relation to each other and have a distance to each other adapted to the thickness of the piece of wood between its flat sides; c) compression of the piece of wood between its side surfaces in radial direction to the annular rings of the wood using increasing compression force until a wanted compression has been reached.
• a device to provide the method is characterised by a) a piece of wood having standing annular rings perpendicular to the flat sides of the piece of wood; b) two plates having a fixed position in relation to each other and having a distance to each other adapted to the thickness of the piece of wood between its flat sides, and between the two plates the piece of wood is adapted to be placed; b) press means for compressing the piece of wood between its side surfaces in radial direction of the annular rings of the wood and with increasing compression power until a wanted compression has been obtained.
• FIG 1 illustrates a compression in accordance with a prior known method, described above
• FIG 2 illustrates schematically a first embodiment of a system according to the invention
• FIG 3 illustrates a second embodiment of a system according to the invention
• FIG 4 shows a diagram, by means of which the invention is explained
• FIG 5 illustrates a third embodiment of a system according to the invention
• FIG 6 shows a longitudinal section through a first embodiment of a press having feeding of a longitudinal timber of wood to be treated and batch wise compression of the wood
• FIG 7 illustrates a longitudinal section through a second embodiment of a press having feeding of a longitudinal timber of wood to be treated and continuous compression of the wood
• FIG 8 illustrates a longitudinal section through a third embodiment of a press having feeding of a longitudinal timber of wood to be treated and continuous compression of the wood.
• FIG 2A shows a wood board 1 in the form of a piece of wood having standing annular rings.
• a wood board 1 is made for example by means of quarter or star sawing.
• the centre part of a timber log obtained when using through or square cutting can be used, for example having the pitch and a part of the juvenile wood cut away.
• the wood cut in this way is dried at least to the fibre saturation point, but preferably longer, for example to ca. 10% humidity in the wood. Thereafter, the limbs with the surrounding cross grain are cut away. Woods are joined as needed, for example with finger joint.
• the wood 1 prepared in this way is placed between two plates 3 and 4.
• Each plate has a glossy surface turned towards the wood and preferably has a coating 5 and 6, respectively, providing a low friction to the wood.
• the purpose of having the glossy surfaces of the plates 3 and 4 is to give such as low force of friction from these plates as possible when the wood board is compressed during the compression to come.
• the distance between the plates 3 and 4 should be approximately as long as the thickness of the board. Preferably, the distance could be controllable, e.g. by means of a steering wheel or the like (not shown). It is also an advantage to be able to move away one of the plates 3. 4 during working moments with insertion of an untreated wood board and unloading of a treated wood board. However, the positions of the plates 3 and 4 are essentially fixed, when a wood board is placed between them in order to be treated.
• a pressure force is imposed on the edge sides of the wood board 1 in the direction of the arrows PI and P2.
• the pressure force is provided by a press arrangement having pressure providers 7, 8 and a pressure foot 9, 1 1 on each edge side.
• the two pressure providers are controlled by a control unit 1 1. which also can sense the total pressure, to which the wood board 1 is exposed. It is to be noted that the way shown having edge pressure from both directions is to be preferred. However, it is also possible, as shown in FIG 3. to have a fixed holder-on 12 at one side of the wood board and apply the pressure P3 against its other edge side using the same kind of pressure arrangement 8, 10 as in FIG 1 controlled by a control unit 13.
• the compression can go on until a strong increase of the pressure resistance is provided. This occurs when the wood board has got a density in the order of 1200 kg/m . A spring back occurs when the pressure force is released, but remaining density for pine wood spruce is ca 800 kg/m , i.e. somewhat lower than the original density of the summer wood.
• FIG 4. A diagram of the pressure force as a function of compression is shown in FIG 4.
• a first phase having increasing pressure force up to BR1
• no essential compression is provided.
• a strong compression using a small extra pressure force is provided up to BR2
• the pressure force has to be increased essentially in order to get a small increase of the compression.
• the compression is finished when the pressure force has reached a predetermined level that according to observed results is known to represent the maximal compression before an extra pressure increase will lead to a hardly noticeable effect.
• the pressure force could be maintained constant during a certain time.
• the material is floating during this time, and a certain tension relaxation is obtained.
• chemical or fhermo- mechanical locking which means that the piece of wood 1 for instance has been impregnated with some chemical substance before compression, which substance hardens during compression. Or else that heat is provided, particular during the end phase having constant pressure.
• the piece of wood board can be attached, for example glued, on a fixating bed, e.g. a plate of wood 14.
• a fixating bed e.g. a plate of wood 14.
• This fixation may be made only directly on one side of the wood board.
• two compressed wood boards 1, 1 ' could be attached on each side of the fixating bed in order to get symmetry such that the composite wood board does not bend.
• the fixating bed strives against the effect provided when the compressed wood board has a possible tendency to swell in the compression direction.
• the bed 14 should not be made thicker than that the glue is holding in on place, it should be so thin that it does not press itself away from the glue.
• the bed 14 could at such a use be protruding somewhat at one side and be notched somewhat at the other side such that pieces of wood board having groove and tenon are created in this way.
• FIG 3 illustrates that a piece of wood 10 before the compression could be sawn into radial sliced veneer (shown sparsely for clearness), which thereafter are laid one of top of the other between the plates 15 and 16. Thereafter the compression is provided from the edges, which results in hard veneer disks, which can be used for example to wear and tear layers on floors, kitchen shelves, kitchen shutters etc.
• FIG 5 shows that two triangular blocks 17 and 18 have been glued together such that the glued common block 20 has got standing annular rings.
• Two blocks 19 and 20 provided in this way have thereafter, having an insert 21 between them, been placed between fixedly placed plates 23 and 24. After that the blocks are compressed from the edges in order to get a harder and stronger material.
• the distance plates are not shown in FIG 6 since they are provided in front of and behind the section shown in the Figure.
• the plank is fed in through an opening in the right side of the Figure between a press arrangement having two longish pressure units 26 and 27 having different pressure forces along the plank 25.
• the plank is fed through the press arrangement in the direction of the arrow P5 and is then compressed more and more in the beginning (see the section from the beginning to BR1 in FIG 4). After that, the plank is exerted to a pressure, which increased in a lower rate (see the section between BR1 and BR2 in FIG 5). After that, the control unit (not shown in FIG 6) senses that the pressure should not increase any more the pressure is maintained constant in the end of the pressure chain along the plank 25.
• the pressure along the plank is here controlled to have different pressure power in dependence of the position along the press units. This is possible to make by means of the control unit in a way obvious for the person skilled in the art.
• the press units 26 and 27 could have a coating giving a low friction. This is advantageous even if the press is opened somewhat at each movement forward.
• a chain of press plates 27, 28 has been placed between a guide (work support) 29 and 30 each for the belonging press units 31 and 32, respectively, and the plank 25.
• the press plates 27 and 28 are fed in the direction of the arrows such that they help the feeding movement of the plank 27 through the press arrangement. In doing so the press plates do not need to be opened between the batch wise compression, and the pressure proceeding can be provided continuously.
• Each chain of press plates can be fastened to each other in a ring and be fed around as an endless band.
• the method according to the invention can be used for each kind of wood where it is a wish to increase its hardness and resistance.
• a corresponding increase of the tear- proof, compression strength and resistance to bending for the wood is provided in the similar way as described above for the hardness.
• the method is particularly advantageous for fast-growing wood, which in itself has deficient resistance values, for example quick growing spruce planted on arable land.
• the method is adapted for treatment of needle as well as leaf wood.
• the pieces of wood treated to be hard with the method according to the invention are principally thought to be used a floor covering.
• the hardness has been derived by compression sideways and thus not by compression from the flat sides.
• the E-module at tangential load, i.e. on surfaces along a radial plane is much lower than that on tangential surfaces.
• the manufacturing method according to the invention if it is used to making floor boards, thus gives an aesthetically attractive floor having its standing annular, narrow rings.
• the floors are also pleasant to walk on.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mechanical Engineering (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Debarking, Splitting, And Disintegration Of Timber (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=20415632

Family Applications (1)

Country Status (6)

Cited By (1)

Family Cites Families (5)

• 1999
  • 1999-05-17 SE SE9901796A patent/SE515328C2/sv unknown
• 2000
  • 2000-05-17 AT AT00931857T patent/ATE251976T1/de active
  • 2000-05-17 EP EP00931857A patent/EP1202848B1/de not_active Expired - Lifetime
  • 2000-05-17 WO PCT/SE2000/000976 patent/WO2000069606A1/en not_active Ceased
  • 2000-05-17 DE DE60005968T patent/DE60005968T2/de not_active Expired - Lifetime
  • 2000-05-17 AU AU49674/00A patent/AU4967400A/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events