JPH0720602B2 - Adhesion method for veneer veneer with back crack and other board - Google Patents

Description

The present invention relates to a method for bonding a veneer veneer having a back crack to another plate material.

On the back surface of veneer veneer (hereinafter simply referred to as veneer) machined from veneer lace / slicer, etc., local tears along the fiber caused by bending during cutting,
It is well known that a large number of so-called back cracks are present at every interval related to the thickness of the veneer, and the back cracks have a shallow absolute depth as the veneer thickness decreases. Although it is possible to suppress the depth by properly setting various cutting conditions, it is essentially difficult to prevent, and as shown in FIG. Due to its presence, the veneer 1 usually bends in the orientation shown.

By the way, as shown in FIG. 9, other suitable plate materials, for example, relatively thin ones, are appropriately dried with or without drying the curved single plate 1 as described above, and as illustrated in FIG. When bonded to the veneer 3 having no significant back cracking, it is inevitably flattened, but since the inner surface of the back crack 2 is formed by tearing and is rough, it is simply the veneer 1 Is only flattened, it is difficult to restore the state of close contact, and a phenomenon in which a gap is formed at least in part is caused, and the existence thereof becomes remarkable.

Also, as a special example, when turning a very thick veneer from a relatively thin log, veneer 1
May reversely curve, and in this case, a phenomenon in which a gap is formed in at least a part of the back crack 2 is promoted as the surface is flattened, and the presence thereof is also remarkable.

The gap of the back crack tends to relatively increase to the absolute depth of the back crack, and when bonded without drying, regardless of the presence or absence of a curve or the direction of the curve, as the drying progresses, The gap in the central portion of the veneer that is not constrained from shrinking tends to increase more and more, but in any case, the manifestation of such back crack becomes a factor that deteriorates the quality of the product obtained by bonding.

Conventionally, such a veneer in which back cracking is exposed is mainly used on the inner side of the product, and the product is selectively used for applications in which the surface of the mouth where back cracking is most exposed is not exposed to the surface. As a result, the fact that the occurrence of back cracking is actually tolerated is the actual situation, but it must be a factor that deteriorates the product quality and restricts its application. In a product such as a plate laminated material which has a possibility of being exposed with various surfaces exposed, the occurrence of back cracking may be a fatal defect.

The present invention, when bonding a single plate having a back crack and another suitable plate material, by providing a novel bonding method capable of bonding so as not to reveal the back crack, by improving the quality of the product, Therefore, the purpose of the product is to be expanded, and specifically, a veneer having a back crack is slightly pressured in the direction orthogonal to the fiber, and an adhesive is used. It is configured to be bonded to another plate material.

According to the bonding method having the above-mentioned structure, the veneer having a back crack is slightly pressurized in the direction orthogonal to the fiber,
In other words, in a state of being compressed in a direction intersecting with the back crack, it is bonded integrally with another plate material, and even after the pressure applied by the external force is released, the other plate material and the adhesive Since the compressed state is maintained almost as it is due to the reinforcement effect by, the phenomenon that a gap is formed in the back crack portion is regulated, and the occurrence of the back crack is prevented or significantly reduced.
This is effective because the quality of the product is improved and the applications of the product are expanded accordingly.

Hereinafter, the present invention will be further described in detail together with an actual example illustrated in the drawings.

FIG. 1 is a front explanatory view of a bonding apparatus used for carrying out a bonding method according to the present invention.

In the figure, 4 and 5 are a pair of hot plates heated to an appropriate temperature by an appropriate heat source such as heating steam, and one hot plate 4 is the other hot plate by an elevating function 6 composed of a fluid cylinder or the like. It is forcibly moved up and down in the direction away from and in contact with 5.

Reference numeral 7 denotes a pair of pressing members disposed on both the left and right sides of the heating plates 4 and 5, respectively, and a moving mechanism 8 including a fluid cylinder or the like forcibly reciprocates the respective members in a direction in which they separate from and contact the other. Be punished.

The bonding method according to the present invention is carried out, for example, by using a bonding device having the above-described structure, and a thin veneer 1 is formed on both front and back surfaces of a veneer 1 having a back crack 2 via a urea adhesive, for example. The semi-finished product in the state of stacking 3 with the fiber directions crossing,
After being inserted between the hot plates 4 and 5, the elevating mechanism 6 lowers the hot plate 4 to a desired position, for example, a position where the hot plate 4 contacts the upper single plate 3, and the moving mechanism 8 moves the pressing members 7 to each other. By bringing them closer to each other, the veneer 1 is slightly pressurized in a direction orthogonal to the fibers, and the hot plate 4 is further lowered to further compress the veneer 1 and the veneer 3 as necessary. The urea-based adhesive is heated and cured through the veneer 3 to bond the veneer 1 and the veneer 3 together.

According to such a bonding method, the veneer 1 having the back crack 2 is
In a state of being slightly pressurized in a direction orthogonal to the fibers, in other words, in a state of being slightly compressed in a direction intersecting with the back crack 2, the thin veneer 3 is integrally bonded and applied. Even after the pressure is released, the thin veneer 3 and the adhesive provide a reinforcing effect, and the compressed state is maintained almost as it is. Therefore, the phenomenon in which a gap is formed in the back crack 2 is regulated, Since the occurrence of the back crack 2 is prevented or significantly reduced,
More practically, the quality of the product is improved as compared with the conventional product, because it is made invisible so that it cannot be easily identified by the naked eye.

Of course, the above-mentioned action and effect are not limited to the surface of the product,
Since it extends to the inside, the inside of the product will eventually be exposed on the surface, for example, when the product is subdivided and used, or when a groove or hole reaching a veneer with a back crack is formed in the product. Even if it is used, it can be applied without any problems, and it is effective because it broadens the application of the product as a whole.

In the embodiment illustrated in FIG. 2, a stopper 9 is provided at one end of the hot plate 4 which is lifted and lowered by a lifting mechanism 6 in a direction in which the hot plate 5 is moved toward and away from the hot plate 5.
On the side opposite to the above, using a bonding device comprising a pressing member 7 which is reciprocally moved in the direction of the arrow by a moving mechanism
Pressing from one side by the pressing member 7 and the stopper 9
This is an example in which the veneer 1 having the back cracks 2 is bonded to the thin veneer 3 integrally with the thermosetting adhesive while the veneer 1 having the back crack 2 is slightly pressurized in the direction orthogonal to the fibers. However, even in such a case, the development of a gap in the portion of the back crack 2 is regulated, and as a result, the back crack 2 becomes invisible, the quality of the product is improved as compared with the conventional product, and the application of the product as a whole is improved. Is also effective because it expands.

Incidentally, the back crack is, as shown in the figure, from the forming process.
Since there is a characteristic that the cross-sectional shape bends in a substantially V shape, when pressing from only one side as in the above embodiment, it is necessary to press from a direction that promotes a substantially V-shaped bending degree as shown in the figure.
It is convenient because pressurization is easy and the pressure is averaged.

The above is a specific outline of the bonding method according to the present invention.
In order to further clarify the gist, the individual requirements will be described in more detail below.

As mentioned above, if a veneer with back cracks is used without drying, back cracks may become apparent eventually, so it is easy to increase the degree of pressurization a little to prevent it. -Considering the adhesiveness and the like, undried ones are not always suitable, but on the other hand, once the gap between the back cracks is fixed during the drying process, it is difficult to close and a large amount of pressure is required. Those that are almost dry are not optimal.

Therefore, use a material that has been pre-dried to a moisture content of around 30% at which contraction becomes apparent, or a moisture content close to that, and if necessary, use heat to the adhesive to bond with or at the same time. Experiments in the recurrence process of the present invention revealed that it is practical to separately heat and subsequently re-dry it forcibly, or to naturally dry it after bonding. The degree of pressurization in the direction orthogonal to the fibers should be appropriately selected in consideration of various conditions such as the drying rate of the veneer, the strength of the plate, the quality of the product, and the application. It is not preferable that the excess or deficiency destabilizes the properties of the product after releasing the pressure.

On the other hand, as the other plate material, a plate material that can maintain the compressed state of the veneer having a back crack almost as it is by using together with an adhesive is sufficient. In addition to wood-based board materials other than veneered board, or veneer composed of plywood, particle board, hard board, etc., for example, gypsum board, synthetic resin board, metal board, paper, cloth It is possible to apply a wide-sense plate material including heterogeneous plate materials, etc., and it is not necessary that the plate material is appropriately selected from them and used alone or in a plurality, and it is not necessarily a single sheet. In the case of using the single plate having the above as another plate material, it is desirable to bond the fibers in a state of being slightly pressurized in the direction orthogonal to the fibers in order to make the back crack non-visible.

Furthermore, the state of adhesion of the other plate material may be either a form of adhering to both front and back surfaces of a veneer having a back crack, or a form of adhering to any one side thereof. It is desirable that the veneer has an adhesive form in which it is difficult to expand and contract in the direction orthogonal to the fiber when the pressure on
As a preferable bonding mode in which a single plate having a relatively weak strength in the direction orthogonal to the fibers is used as another plate material, in addition to the bonding modes as in the above-mentioned Examples, for example, as illustrated in FIG.
A back surface of a veneer 1 having back cracks and a back surface of a veneer 10 having a noticeable back crack 2 and having different plate thicknesses are adhered in the same fiber direction, as illustrated in FIG. As described above, the back surface of the veneer 1 having the back cracks 2 and the surface of the veneer 11 having the same plate thickness (substantially the same veneer as the veneer 1) having the remarkable back cracks 2 are arranged in the fiber direction. Are aligned and superposed, and two thin veneers 3 are adhered to the front and back sides with the fiber directions intersecting each other.
Further, as illustrated in FIG. 7, a veneer 1 having a back crack 2
Veneer and the veneer with the same thickness, which had remarkable back cracking 2.
In the case where the back surface of 11 and the back surface of 11 are bonded by crossing the fiber directions, in each case, the adhesive action of the adhesive is obtained so that adjacent veneer members mutually suppress expansion and contraction of the fiber in the orthogonal direction. Therefore, it is listed as part of the examples.

On the other hand, as the adhesive, a urea-based adhesive (including co-condensed resins such as urea melamine co-condensed resin) used for manufacturing plywood and the like is convenient because of its properties and price,
Even if the veneer with a back crack has a somewhat high water content, effective adhesion is possible if the water content of the adhesive is vaporized to some extent after application and then the adhesion is achieved. Without limitation, other thermosetting adhesives, room temperature curable adhesives, thermoplastic adhesives, wet curable adhesives, etc. are selected from various known adhesives according to desired conditions, They may be used alone or in combination, and may be used in combination with other additives such as flame retardants, if necessary.

As a matter of course, the bonding device used for carrying out the bonding method according to the present invention is not limited to the devices having the configurations of the above-mentioned both embodiments, and various configurations including the devices described later can be used. Therefore, the adhesive may be configured by being adapted to the properties of the adhesive and the properties of other plate materials, and the point is that the adhesive is applied in a state in which a single plate having a back crack is slightly pressurized in the direction orthogonal to the fiber. Any material that can be bonded to another plate through the above is sufficient.

When the veneer having back cracking is slightly pressed in the direction orthogonal to the fibers, if the veneer buckles, the pressurization will be incomplete and uneven, so it is desirable to prevent it. When the other plate material has sufficient rigidity to prevent buckling, it is preferably regulated by the plate material or by the hot plate in both the above-mentioned examples, preferably a single plate having back cracking. It is effective to prevent buckling by arranging a member capable of directly or indirectly controlling buckling on both front and back sides, but to the entire surface of the veneer having back cracks, directly or When a member capable of indirectly controlling the buckling is brought into contact with the member to regulate the buckling, a frictional force is generated over the entire surface,
In particular, when the width of the single plate having the back crack in the direction orthogonal to the fiber is relatively wide, control due to the frictional force may cause uneven pressurization in the direction orthogonal to the fiber. It is desirable to take the measures described below.

That is, for example, as illustrated in FIG. 3, the heating plate 4 on one side is divided into a plurality of parts and is configured to be able to move up and down separately, and at the beginning, the distance between the heating plates 4a and 4c close to the pressing force indicated by the arrow P. T1
Is slightly wider than the contact distance T2 of the heating plate 4b far from the pressing force, and after pressing the single plate having the back crack in the direction orthogonal to the fiber, the interval T1 is The hot plates 4a and 4c are further lowered so as to be aligned with T2 to perform the bonding, or the hot plate 4 can be arbitrarily tilted as shown in FIG. Hot plate 4 close to pressure
In the state in which the hot plate 4 was tilted so that the distance T3 between Nos. 5 and 5 was slightly wider than the contact distance T4 on the stopper 9 side, the single plate having the back crack was slightly pressurized in the direction orthogonal to the fiber. After that, it is desirable to equalize the pressurization by taking measures such as further lowering the side closer to the pressing force of the hot plate 4 so that the interval T3 is aligned with the interval T4 and performing bonding.

Although not shown in the figure, initially, while partially restricting buckling, the veneer having a back crack is slightly pressurized in the direction orthogonal to the fiber, and then compression / heating etc. are applied to almost the entire surface. In order to implement it separately from the bending control, it is also possible to configure members and mechanisms with different functions by interleaving each other so that the frictional force is generated locally only locally. This is effective for equalization, but conversely, if the braking caused by the frictional force is positively utilized, for example, in the device of the embodiment shown in FIG. It is also possible to carry out, or it is not impossible to carry out continuous extrusion processing in a core type by combining with a known continuous press or the like.

According to the bonding method of the present invention, which is based on the above-mentioned various elements, it is extremely thick (for example, 10
mm or more) It is effective because a veneer having a back crack, including veneers, can be used very effectively, and high quality products can be finished, and the applications of the products are expanded accordingly. The implementation effect on the veneer related industry is extremely large.

[Brief description of drawings]

The drawings are for explaining the present invention. FIG. 1 is a front explanatory view of a bonding apparatus used for carrying out the bonding method according to the present invention, and FIGS. 2 to 4 are drawings for explaining the bonding method according to the present invention. A front explanatory view of another bonding apparatus used for implementation, FIGS. 5 and 6 are side explanatory views of a product bonded by the bonding method according to the present invention, and FIG. 7 is a side view of a product bonded by the bonding method according to the present invention. FIG. 8 is a perspective explanatory view, FIGS. 8 and 10 are side explanatory views of a single plate, and FIG. 9 is a side explanatory view of a product bonded by a conventional bonding method. 1 ... Single plate with back cracking, 2 ... Back cracking, 3 ... Thin single plate, 4,5 ... Hot plate, 6 ... Lifting mechanism, 7 ... Pressing member, 8 ... Moving mechanism, 9 ...... Stopper, 10,11 ...... Veneer with remarkable back cracking

Claims (7)

[Claims] 1. When adhering a veneer veneer having back cracks to another plate material with an adhesive, the veneer veneer having back cracks is slightly pressurized in a direction orthogonal to the fibers, A method for adhering a veneer veneer having back cracking characterized by adhering and another plate material. 2. A method for adhering a veneer veneer having back cracks to another plate material according to claim 1, wherein the veneer veneer is used as another plate material. 3. A method for adhering a veneer veneer having back cracks to another plate material according to claim 2, wherein a veneer veneer having no noticeable back cracking is used as another plate material. 4. A method for adhering a veneer veneer having back cracking to another plate material according to claim 2, wherein a veneer veneer having remarkable back cracking is used as another plate material. 5. A veneer veneer having back cracks according to claim 1, wherein a wood-based plate material other than veneer veneer composed of plywood, particle board, hard board, etc. is used as another plate material. Adhesion method with other board materials. 6. A veneer veneer having a back crack according to any one of claims 1 to 5, wherein another veneer is adhered to both front and back surfaces of the veneer veneer having a back crack. How to bond a board to another board. 7. A veneer having a back crack according to any one of claims 1 to 5, which is formed by adhering another plate member to one surface of a veneer single plate having a back crack. Adhesion method between a single plate and other plate materials.