EP0107690B1 - Method and device for transforming billets into construction wood - Google Patents

Abstract

In the method for transforming billets into construction wood with vertical annual growth circles or into plywood, the billet is first cut into sections of a length easy to handle, the billet is milled in circles, and the trunk is divided into wedge-shaped circles which are glued together. At least two wedge-shaped sectors (4, 4a) kept out in the cross-section of the trunk are arranged one on top of the other, one face (7, 8) of each wedge being provided with a layer of glue so that the other faces (5, 6) of the wedges are parallel and the growth circles (3) are upstanding. The sectors (4, 4a) are then pressure glued. To this effect, a device having two bearing surfaces (13, 14) arranged in parallel to each other at a distance Y is used, on which bearing surfaces the surfaces (5, 6) of a block of sectors (17, 27) are resting. The sectors 94, 4a) are parallel to the bearing surfaces (13, 14) and may be subjected to pressure by using pressure transmission means.

Description

The invention relates to methods for processing tree trunks to construction wood with standing annual rings, in which the tree trunks are first cut into lengths and then divided into wedge-shaped sector pieces which are mutually glued together and a device for carrying out the method.

When extracting sawn timber from round timber, mainly the core area is used for the extraction of sawn timber, while the partially rounded side timber is cut for further processing into chipboard. The possibilities for the direct use of the side timbers are small because of the difficulties caused by the round cross-sectional limitation and only of a subordinate nature. It has become known to profile the side timbers at the edges in such a way that they can be used as planks or the like . However, it has been shown that such processing of the side timbers is too difficult. Neither the round boundary surface nor the acute-angled and therefore imprecise side edges allow reliable guidance in planing or milling machines. For this reason, e.g. Bar planks for panel cladding mainly made from the valuable sawn wood of the core area of the trunks. The use of the timber cross-section is therefore more impaired due to the poor usability of the side timbers, the smaller the log diameter.

A particular problem in wood processing is working the wood, i.e. its change in shape due to swelling and shrinking when moisture is absorbed or released. In addition to this disadvantageous property is the anisotropy of the wood, which causes the wood to swell or shrink to different extents in the three different anatomical directions - longitudinal, tangential, radial. The swelling or shrinkage is tangentially approximately twice as large as radial, the change in length in the axial — that is to say longitudinal — direction being negligible. This means that the stamina so important for construction timbers is directly dependent on the position of the annual rings in the wood cross-section. In the conventional way of cutting wood, boards, squared timbers or beams with always different annual ring positions are produced, with the yield of timber being relatively poor. The manufacture of boards and wooden parts with standing annual rings has so far regularly led to poorer utilization or has required compromises with regard to the position of the annual rings.

From the American patent US-A-3 967 654 a method for processing tree trunks into board-like construction wood with standing annual rings is known, in which the tree trunks to be processed are cut into standard lengths and then divided into diameter classes. In these diameter classes, the trunk sections are then broken down into wedges. These are then alternately glued to one another alternately. The rind is then removed from the glued wedges on the outside in order to obtain defined smooth surfaces. The resulting pieces of wood, which have a parallelogram-like cross section, can then be joined together over their outer surfaces, for example by gluing, to form larger wooden units, the outer surfaces also being able to be profiled for better connectivity. This prior art is the starting point for claims 1, 2 and 4.

From the Swiss patent CH-183513 a process for the production of middle layers is known, in which a trunk is cut into wedge-shaped parts, which are then glued together to form a large block, which is cut into boards with standing annual rings. This prior art is the starting point for claim 5.

The object of the invention is to improve the wood yield and economy in the production of construction wood for the general application of the principle of the mutual gluing of wedges, whereby construction wood is understood to mean board and veneer-like composite wood products with only standing annual rings.

This object is achieved by the independent process claims 1, 4 and 5 and by the independent device claim 2.

Claim 3 gives an embodiment of the device according to claim 2, claims 6-8 indicate embodiments of the method according to claim 5.

The invention is explained in more detail below with reference to the drawings.

It shows

• 1 is a schematic representation of the construction of a structural part according to the invention from sectors of a log in a side view in section,
• 2 shows a longitudinal connection of two structural members in a schematic side view in section,
• 3a possible embodiments of cross connections and,
• 3b of construction timber in a schematic cross-sectional view,
• Fig. 4a a required for veneer production and
• 4b construction part in cross-section,
• Fig. 5a the veneer pattern on a construction part in and
• 5b separating cuts made in different directions,
• 6a embodiments of an inventive and
• 6b sawing device and drying device in schematic views,
• Fig. 7a the pressing device for the production of sector blocks and

7b in a schematic cross section.

As shown in FIG. 1, wedge-shaped sectors 4, 4a are produced from the round wood 1 by mirror cuts. At least two wedge-shaped sectors 4, 4a are placed opposite one another in such a way that the sector surfaces 7, 8 touch and the outer sector surfaces 5, 6 are arranged parallel to one another. A glue layer is provided between the sector surfaces 7, 8 and serves to connect the sectors 4, 4a to a sector block 117.

If extended construction timbers are desired, it is possible to connect construction timbers 9 formed from the sectors 4, 4a to one another at the end faces 18, 19. For this purpose, for example, finger joints 10 can be formed on the end faces 18, 19 in a manner known per se (FIG. 2), the surfaces of which are coated with a layer of glue. By compressing the structural parts 9 in the longitudinal direction, their dimensionally stable connection then takes place. With a connection by means of finger joints 10, however, a slight loss of material must be accepted.

It is also possible to produce 17 construction parts of greater width from sector blocks. For this purpose, it is only necessary to form finger joints 10 on the longitudinal sides 20, 21 of the segment blocks 17 to be connected, for example, to coat the toothing surfaces with glue and then to press the individual sector blocks against one another by applying lateral pressure. It is also possible to remove the round end section 22 of each sector block 17 by means of a separating cut and then to glue the sector blocks 17 together on their smooth milled edge surfaces 23 (FIG. 3a). By milling the round end section 22, an oblique edge surface 23 is achieved, but is no longer perceptible after the gluing. 3b shows another possibility of connecting two sector blocks 17. Finger tines 24 are formed on the round end sections 22 of the sector blocks 17 to be connected to one another such that the finger tines 24 of the one sector block 17 can be inserted into the grooves 25 between the finger tines 24 of the other sector block 17. The finger tines 24 can be held in the grooves 25 both by clamping action and by gluing. This toothing shown in FIG. 3b has the advantage that no material loss occurs in the region of the round end sections 22. In addition, the effective glue area is increased and guidance is achieved by the finger tines 24 and grooves 25. For special applications such as for floor boards or form boards, sector blocks 17 provided with finger tines 24 and grooves 25 can therefore also be joined together without glue, such as tongue and groove boards. If several sectors and sector blocks 17 are to be joined together to form a large sector block 27, devices 12d, 12e can be used (FIGS. 7a and 7b). Both devices have a stop 28 arranged on the lateral end section 26 of the stop surfaces 13, 14, against which the side end sections 26 facing it can be brought into contact. In the device 12d, in the area of the other lateral end section 30, pressure stamps 16 act on the sectors 4, 4a and sector blocks 17 arranged between the stop surfaces 13, 14.

It is also possible to use, for example, elastic pressure-resistant hoses 32 instead of the pressure stamp 16 (FIG. 7b). In this case, a stop 31 is formed on the lateral end section 30, on which the elastic pressure-resistant hoses 32 can be fixed in their position. In the device 12e, elastic pressure-resistant hoses 32 are arranged alternately between the round end sections 22 of the sectors 4, 4a and the stops 28, 31. The holding means for fixing the position of the elastic pressure-resistant hoses 32 are not shown in more detail. The formation of veneer strips is expediently carried out in such a way that a sector block 27 is first produced, then a cut is made in the direction X in the direction X parallel to the sector area 6. It is also possible to make this separating cut in the direction X (FIGS. 4a and 4b).

In the case of a separating cut in the direction X, the veneer has a stripe pattern, as is shown schematically in FIG. 5a. With a separating cut in the X direction, a flat image is achieved for the veneer. For veneer production it is necessary that the sector blocks 27 have to be moist before the separating cuts. In contrast to the production of a construction timber, it is expedient and, in the case of certain woods, also necessary for sectors 4, 4a to be glued with moisture. Since it is only the veneer that counts in the production of veneers and not the stamina, the annual rings 3 do not need to be very straight. Furthermore, it is possible to use sectors 4, 4a with a larger wedge angle than is the case for the production of construction timber. The sectors 4, 4a of a trunk are expediently glued to form a large sector block 27, since this avoids frequent clamping in the veneer knife machine and better material utilization is achieved.

In order to be able to make optimum use of the trunk cross-section of the round timber 1, it is expedient to use two sectors 4, 4a with a wedge angle of 22.5 ° and seven segments with a wedge angle of 45 ° for a large sector block 27.

By using the described method, it is possible to achieve a uniform and high quality with very high material utilization to achieve a product. A dome production is not necessary. Rather, tree trunks of different diameters can be processed. In addition, different wedge angles of the sectors 4, 4a are possible, as a result of which the degree of quality can be controlled. When carrying out the method according to the invention, the best possible material utilization compared to known methods results. Sorting boards during further processing, for example on the right or left side, is not necessary since such boards no longer occur due to the arrangement of the annual rings 3. Conditions previously considered when carrying out wooden structures, such as warping, changes in angle, uneven shrinkage allowance and the like. The like. need not be observed. This simplifies the calculation and standardization of construction parts 9. These can be used anywhere, for example so-called rift boards have previously been required. In addition, an application is possible where previously boards with a changing annual ring course and all the associated disadvantages had to be used, since these were mainly incurred during the incision. The sector blocks 17 can also be used to produce the middle layers for plywood panels, the quality of which then corresponds to the stamina of the so-called rod middle layers with standing annual rings.

Considerable advantages also arise in the case of artificial wood drying in particular. When drying normally cut wood, shrinkage cracks first appear in the radial direction. In order to avoid this, it has previously been necessary to carry out the drying processes carefully and very slowly, which results in high time and energy requirements. As a result of the type of incisions, the radial drying cracks are anticipated when the method according to the invention is carried out. The wedge-shaped sectors 4,4a shrink like any other wood, but do not get lost in the process. Post-processing such as leveling by planing after drying and the associated loss of material is largely avoided. Due to the significantly lower risk of cracks, drying can also be done faster and cheaper.

It is particularly advantageous to produce sectors 4, 4 a or sector blocks 27 by means of a device that consists of a sawing device 33, a drying device 34 that can be loaded with a drying basket 41, and a pressing device 35. The sawing device 33 and the drying device 34 are shown schematically in FIGS. 6a and 6b. The log 1 to be processed is first sawn off in handy lengths and then milled into a circular cylinder. This cylindrical log 1 is then introduced into the sawing device 33. This consists of saw units 36 arranged one behind the other in the feed direction Z of the round timber 1, which can be pivoted about an axis of rotation coaxial with the central axis 37 of the round timber 1 located in the sawing device 33. By appropriate adjustment of the sawing units 36, it is possible for them to make longitudinal cuts in the round timber 1, which are adjusted according to the central angle of the desired sectors 4, 4a. By means of this saw device 33 it is thus possible to achieve a desirable high level of quality, i.e. H. cut out a maximum number of sectors 4, 4a per log 1. As a result, the annual rings 3 are all the more straight in the glued end product, as a result of which the corresponding properties such as stamina, resistance to warping, etc. are particularly good. The saw units 36 are designed so that they can be moved out laterally when not in use, for maintenance, for adjusting or for changing the saw blade. The sawing units 36 can expediently be designed as band saws. For the advancement of the round timber 1 through the sawing device 33, a conveyor device 38 is provided, which has circularly arranged adjustable conveyor rollers 39. The conveyor rollers 39 can be adapted to the respective diameter of the log 1 to be cut, so that the log 1 is always arranged centrally in the sawing device 33. A drying device 34 is arranged at the output of the sawing device 33. The sectors 4, 4a produced in the sawing device 33 are first inserted into a drying basket 41 at the exit of the sawing device 33. In the drying basket 41, the sectors 4, 4a are arranged in a circular cross-section and are held between radially extending holding webs 45. By means of a pressing device 43 the z. B. may consist of compression springs 46, the sectors 4, 4a are pressed as far into the drying basket 61 until they rest flat on the retaining webs 45.

The drying basket 41, which can also be designed as a drying drum, is pushed into the drying device 34 with the wedge-shaped sectors 4, 4a and can be rotated therein. Nozzles 47 are formed in the wall 44 of the hollow chamber 42 of the drying device 34, through which drying air is blown into the hollow chamber 42. Exhaust air openings (not shown in more detail) are provided diametrically to the nozzles 47, so that full-area transverse ventilation in the drying device 34 is achieved. It is possible to design the air flow by means of suitable air guiding means so that either the entire lateral surface or only a part of it is acted upon. By appropriately designing the nozzles 47, it is possible that when the drying basket 41 rotates, only the space between two sectors 4, 4a is intensively flowed through with the drying air. For this reason, the holding webs 45 are formed such that a space through which drying air can flow is formed between the sectors 4, 4a. The drying device 34 is the same for all conventional drying processes Air movement work such as B. warm air, hot air, steam, condensation drying u. Like applicable.

By using the drying basket 41, otherwise usual stacking work for the material to be dried is avoided. With regard to the wedge-shaped design of the sectors 4, 4a, an extremely favorable use of space is achieved by the star-shaped arrangement. If the drying basket 41 is filled with the sectors of a round timber 1, there are advantages for the further processing stages, since e.g. B. sorting of individual sectors 4, 4a is no longer required. In addition, the formation of the drying device 34 prevents a different air speed over the material to be dried, which provides additional protection against warping.

In addition to the pressing device 35 already shown in FIGS. 7a and 7b, such a pressing device can also be used in which the stop 28 is arranged horizontally and the stop surfaces 13, 14 are horizontally displaceable relative to one another. With such a configuration of the pressing device 35, the segments and tips of the sectors 4, 4a, which are facing away from the stop 28, can be pressurized by means of a pressure plate or pressure rail extending over the entire sector block 27. This design of a press device 35 is extremely advantageous in handling. To produce a sector block 27, the first four sectors 4 are first placed on the stop 28 so that their wide edges touch and the lower right edge of the right sector 4 touches approximately the stop surface 14. Since the focus of the sectors 4, 4a is relatively far below, the sectors 4, 4a remain with their tips pointing upwards. Then the left stop surface 13 is carefully moved until it approximately touches the lower edge of the left sector 4, 4a. Now the remaining sectors 4, 4a or the outer halves of sectors can be placed between them from above. So that with certainty all sector surfaces touch during pressing, the movable left stop surface 13 or right stop surface 14 is now somewhat withdrawn, so that the upper sectors 4, 4a can be pressed down a small way until their tips are between the wide edges of the neighboring sectors 4, 4a protrude slightly. Then the upper pressure plate is fixed and the sector block 27 is pressed under pressure by means of the stop surface 13 or both stop surfaces 13, 14.

The method according to the invention and the device described are suitable for various fields of woodworking. The use in the production of plywood is advantageous, since a high wood yield is achieved in connection with an excellent technological quality of the finished boards. Use in the manufacture of veneers is also advantageous, since round timber 1 of small dimensions can also be used according to the method described. This has the advantage that rotten cores occur relatively rarely and the wood yield is very good. In finished plywood panels, the veneers have standing annual rings. As a result, the swelling / shrinkage potential in the plane of the plywood is only about half that of the known plywood panels. Due to the uniform structure, the internal tensions are so low that the plates also have very good stamina.

Claims (8)

1. Process for processing tree trunks into plank-like construction timber with vertical annual rings, comprising the following steps:

a) dividing up the tree trunk into round timber of a given length;

b) milling the round timber into cylindrical pieces (1);

c) dividing the cylindrical pieces into identical wedge pieces (4a, 4a) with a sector-shaped cross-section;

d) placing and holding two wedge pieces (4, 4a) against each other to form a pair (17) of wedge pieces with parallel outer faces (5, 6), diametrical inner join faces (7, 8) which rest against each other and front faces (18) arranged in two common planes;

e) joint milling of the front faces of the pair of wedge pieces to form a wedge finger joint (10);

f) gluing of the wedge finger joint (10);

g) detaching the holding device for the pair of wedge pieces, opening out the wedge pieces and gluing the join faces (7, 8);

h) offsetting the wedge pieces (4, 4a) relative to each other in the longitudinal direction of the original tree trunk;

i) placing the offset wedge pieces (4, 4a) together and pressing them on the diametrical join faces (7, 8);

j) joining and pressing a previous offset pair of wedge pieces to another offset pair of wedge pieces produced according to process steps a-i at the wedge finger joint (10) and the offset join faces (7, 8) to form a plank-like wooden body with vertical annual rings, which body may in principle be of any length;

k) profiling the cylinder shell-shaped side faces of the plank-like wooden body with a wedge finger joint in such a manner that the flanks of the teeth (24) and grooves (25) lie parallel to the outer face (5, 6) and that, viewed in cross-section, the parallel chords (23) of the circle sections of two wooden bodies placed adjacent each other contact each other after joining.

2. Apparatus for processing round timber comprising at least one sawing apparatus (33) for dividing the round timber into wedge pieces with sector-shaped cross-sections, a drying apparatus (34), a gluing apparatus and a pressing apparatus (35), characterised in that sawing units (36) are arranged one after the other in the sawing apparatus (33) in the direction of advance of the round timber (1), which units are rotatable and adjustable about an axis of rotation coaxial to the centre line (37) of the round timber (1) in the sawing apparatus (33) in such a manner that each sawing unit (36) is adjustable corresponding to the sector angle of the sector (4, 4a), that the drying apparatus (34) consists of a hollow chamber (42) into which drying baskets (41) loaded with the sectors (4, 4a) at the exit of the sawing apparatus (33) can be pushed and can be acted upon by drying air.

3. Apparatus according to Claim 2, characterised in that the drying basket (41) has a circular cross-section and is divided by holding bars (45) into sector-shaped compartments for the wedge pieces in which there are radially outward pressing devices (43) which exert inwardly directed holding forces on the wedge pieces (4, 4a).

4. Process for producing construction timber with vertical annuul rings and low thickness, comprising the following steps:

dividing up the tree trunk into round timber of a given length;

milling the round timber into cylindrical pieces (1);

dividing up the cylindrical pieces into identical wedge pieces (4, 4a) with a sector-shaped cross-section, whereby first of all a cylindrical piece is halved on the longitudinal sides;

boiling the half cylinder or exposing it to steam; rotatable clamping of the half cylinder about its centre line and cutting off of wedge-shaped veneers from the flat surface of the half cylinder with a blade, which veneers are dried and alternately bonded with outer faces which are parallel to each other.

5. Process for producing construction timber with vertical annual rings and low thickness, comprising the following steps:

dividing up the tree trunk into round timber of a given length;

milling the round timber into cylindrical pieces (1);

dividing up the cylindrical pieces into identical wedge pieces (4, 4a) with sector-shaped cross-sections;

halving a sector once again by longitudinal cutting;

keeping the sectors moist by steam or hot water;

smoothing the radial faces;

gluing the sectors in the region of the smoothed faces;

alternate placing together of the sectors to obtain a generally rectangular cross-section of the sector block in that the two halves of the halved sector in each case form the outer end thereof;

pressing the moist sectors to form a solid sector block;

separating veneer strips (11) with strip grain by radial cuts parallel to the flat end faces of the block or with curled spot grain by tangential cuts parallel to the annual rings.

6. Process according to Claim 5, characterised in that the sectors intended for producing the veneers are glued to form a sector block in the moist state.

7. Process according to Claims 5 and 6, characterised in that warm moist to hot moist sector blocks are used for producing the veneers.

8. Process according to Claim 5, characterised in that the veneer strips (11) are cut out of a single pair of the wedge pieces (4, 4a).

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