JPS5917641B2 - How to form cracks in plywood veneer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming cracks in a veneer veneer.

Conventionally, veneer veneers (hereinafter simply referred to as veneers) have been treated to form cracks and impart flexibility to the veneers for the purpose of eliminating cracks, homogenizing them, and preventing overlapping.

One of the typical methods is as disclosed in "Method for manufacturing plywood board" (Japanese Patent Publication No. 37-2791). There is a method in which the veneer is inserted perpendicularly to the fibers into a bending means consisting of opposed small-diameter rigid rollers, and the veneer is bent while being conveyed to form a crack from one side of the veneer. For example, "Method and device for processing plywood veneer"
As disclosed in (% Publication No. 49-32929),
There is a method in which the veneer is inserted into a tensioning means consisting of a pair of elastic rollers in a direction perpendicular to the fibers, and the veneer is conveyed while being pulled using the tensile force generated by the strain of the elastic body to form cracks. However, since they all utilize elastic bodies, they have the disadvantage that the magnitude of the force to form a crack or the position at which it acts is not constant, making it impossible to form cracks stably. Due to factors such as the fact that the cracks that are formed are induced by back cracks inherent in the veneer, the spacing in the direction perpendicular to the fibers of the veneer tends to become smaller (narrower).

As mentioned above, if the intervals between the cracks in the direction perpendicular to the fibers of the veneer are small, and the veneer is essentially fragmented into many rod-like pieces elongated in the direction of the fibers, plywood When forming the veneer, the compressed parts may be crushed, shifted, or rotated, causing problems such as a considerable decrease in the thickness of the veneer, as well as the formation of rod-like pieces. The glued portions are likely to shift or turn even after being bonded, resulting in an inconvenience that reduces the strength of the plywood.

Therefore, in plywood factories, measures are taken to prevent cracks from forming under insufficient conditions by keeping tension or bending to a minimum, or by increasing the amount of adhesive applied to prevent a decrease in plywood strength. The reality is that treatments that cause cracks to form in veneers are being carried out with the main purpose of eliminating cracks, homogenizing, and preventing overlap, and these treatments are not necessarily effective.

The present invention was developed in order to eliminate the drawbacks of the conventional methods, and provides a method that can stably form a large number of cracks with an appropriate spread at approximately desired intervals in a veneer, and While avoiding reduction in board thickness and plywood strength,
The purpose is to enable a process that not only eliminates cracks, homogenizes, and prevents overlapping of veneers, but also causes cracks to form, which can improve yield and plywood quality.The details are as follows. .

In the method according to the first aspect of the present invention, a large number of scratches or cuts are made in advance on the surface of the veneer using an appropriate preforming means.
The pre-formed flaws or cuts are formed at arbitrary intervals in a direction perpendicular to the fibers of the veneer, and then the veneer is pulled or bent in a direction perpendicular to the fibers using an appropriate tensioning means or bending means. By growing the cracks, cracks are formed at controlled intervals, and by forming scratches or cuts on the surface of the veneer in advance, cracks due to tension or bending in the next process can be prevented. The power to form
Since it primarily acts on previously formed flaws or cuts, cracks due to tension or bending will form in such a way as to grow said parts or cuts.

That is, as shown in FIG. 2, for example, after forming a large number of scratches or cuts 14 at arbitrary intervals in the direction perpendicular to the fibers on the surface of the veneer 11, the veneer 11 is cut in the direction perpendicular to the fibers. By stretching or bending, a veneer 12 with a large number of cracks 15 as shown in FIG. 3 can be obtained.

Therefore, by appropriately setting the intervals between the scratches or notches to be formed in advance, cracks can be stably formed at intervals that will not cause a decrease in the thickness of the veneer or a decrease in the strength of the plywood. Moreover, since the cracks are guided along the fibers of the veneer to cause scratches or notches to grow, there is no risk of reducing the strength of the veneer itself, and the spacing between cracks is stabilized so that it can be used in the next process. By fully applying tension or bending to the veneer, it is possible to spread cracks further than before, which not only eliminates cracks in the veneer, homogenizes it, and prevents it from overlapping, but also improves the yield more than before. The practical value in plywood factories is extremely high.

Although not shown in the drawings, the distance in the direction perpendicular to the fibers near the edges in the fiber direction is larger than the distance in the direction perpendicular to the fibers in the center of the veneer in the fiber direction, so that scratches or By forming a cut or by stopping the tension or bending near the fiber direction edges, the fiber direction edges are It is also possible to obtain a veneer with high strength near the edge in the fiber direction, in which many cracks are formed with the spacing perpendicular to the fibers near the edge. In addition to forming scratches or cuts in advance only in the central part of the veneer, tension or bending is applied uniformly to the entire surface of the veneer, and in the central part of the veneer in the fiber direction, the scratches or cuts formed in advance are A veneer with a somewhat higher visual quality (aesthetic quality) after being formed into plywood, in which a large number of cracks are formed at similar intervals near the edges in the fiber direction, respectively, at the same intervals as in the conventional method. Furthermore, it is possible to make the tension near the edge in the fiber direction a little smaller than the tension in the center of the veneer in the fiber direction, so that the tension near the edge in the fiber direction is It is also possible to obtain a veneer with a slightly lower elongation rate than other parts, so the scratches or cuts made in advance and the tensioning or bending in the next process do not necessarily cover the entire surface of the veneer. There is no need for it to be uniform.

Furthermore, if discontinuous scratches or cuts are formed in advance in the direction of the fibers of the veneer, cracks will also be formed discontinuously in the direction of the fibers of the veneer, resulting in complete separation of the veneer. This is preferable because it reliably prevents cracking, and experiments have shown that the spacing in the direction perpendicular to the fibers of the veneer is at least 1.5 times the thickness of the veneer (however, if the crack is on the surface of the veneer) It has been found that there is almost no risk of reducing the thickness of the veneer or the strength of the plywood if it is perpendicular (if it is perpendicular, even less is acceptable), so at least in the center of the veneer in the fiber direction. It is preferable to form scratches or incisions in advance by setting the interval in the direction orthogonal to the fibers to be 1.5 times or more the thickness of the veneer.

Further, as a preforming means for forming a large number of scratches or cuts on the surface of a veneer in advance, for example, as shown in FIG. In addition to the preforming means consisting of the support roller 3 disposed opposite the cutting roller 1, a cutting tool is installed on the circumferential surface of the roller bar in the veneer race, although not shown, in order to streamline the veneer cutting process. A preforming means is used in which a large number of sharp objects such as veneers are attached to form cuts at the same time as the veneer is cut, or a heat source such as a hot wire is used to apply heat to the veneer to cause damage. Various preforming means can be mentioned, such as preforming means,
In any case, the tensioning means consists of a pair of elastic rollers as disclosed in the above publication, and the bending means includes a large diameter elastic roller and the large diameter elastic roller. There is no practical problem in using a bending means consisting of a small-diameter rigid roller disposed opposite to the bending means.

In addition, the method according to the second aspect of the present invention includes making a large number of scratches or cuts in advance on the surface of the veneer at arbitrary intervals in a direction perpendicular to the fibers of the veneer using an appropriate preforming means. When forming the veneer, scratches or cuts are formed in advance so that the spacing in the direction perpendicular to the fibers near the edges in the fiber direction is smaller than the spacing in the direction perpendicular to the fibers in the center of the veneer in the fiber direction. The veneer is then pulled or bent perpendicular to the fibers using suitable tensioning or bending means to grow said preformed flaws or cuts, thereby forming cracks at controlled intervals. For example, as shown in FIG. 4, the number of scratches or cuts 14 in the center of the veneer 13 in the fiber direction is larger than the distance in the direction perpendicular to the fibers. By forming scratches or cuts 14 and 16 on the surface of the veneer 13 by reducing the distance between a large number of scratches or cuts 16 in the direction perpendicular to the fibers in the vicinity of Accordingly, although not shown in the drawings, it is possible to obtain a veneer in which a large number of cracks are formed in a state similar to the state in which the scratches or notches 14 and 16 are formed.

As mentioned above, compared to the spacing in the direction perpendicular to the fibers in the center of the veneer, a large number of cracks occur at intervals that are controlled by making the spacing in the direction perpendicular to the fibers near the edges of the veneer smaller. As exemplified in the description of the method according to the first aspect of the present invention, the formed veneer has a large number of fibers with substantially uniform intervals in the direction perpendicular to the fibers over the entire width of the veneer in the fiber direction. Compared to the veneer with cracks and the spacing perpendicular to the fibers in the center of the veneer in the fiber direction, there are many cracks with the spacing perpendicular to the fibers near the edge of the veneer as a dog. The visual quality of the plywood after being formed is extremely high compared to that of a veneer on which plywood is formed, and according to the method according to the second invention of the present invention, As exemplified in the explanation, by forming scratches or incisions in advance only in the central part of the veneer in the fiber direction, and applying tension or bending uniformly to the entire surface of the veneer, the central part of the veneer in the fiber direction is Compared to the case where a large number of cracks are formed at intervals corresponding to pre-formed scratches or notches, and at the same intervals as in the conventional method near the edges in the fiber direction, this method is more effective. A veneer with high visual quality can be obtained stably and reliably, and is extremely effective in practice.

In addition, the flaws or cuts in the center of the fiber direction may be made discontinuous by dividing the veneer into multiple parts in the fiber direction, or the intervals in the direction perpendicular to the fibers in the center of the fiber direction may be The thickness of the veneer is set at 1.5 times or more than the thickness of the veneer, and scratches or notches are formed in advance. The effect of slightly reducing the tensile strength in the method according to the first invention is the same as that described in the description of the method according to the first invention, and the preforming means is the same as that described in the method according to the first invention. As described in the explanation, the distance in the direction perpendicular to the fibers near the edge of the veneer is smaller than the distance in the direction perpendicular to the fibers in the center of the veneer in the direction of the fibers. The tensioning means and bending means described in the description of the method according to the first invention can be used as they are.

Next, in the method according to the third aspect of the present invention, a large number of scratches or cuts are made in advance on the surface of the veneer at arbitrary intervals in a direction perpendicular to the fibers of the veneer using an appropriate preforming means. The veneer is then pulled in a direction perpendicular to the fibers using a suitable tensioning means to cause cracks to form at controlled intervals by growing the previously formed flaws or cuts. Using a tensioning means having a two-stage conveyance mechanism, a conveyance mechanism on the side and a conveyance mechanism on the output side that is driven at a conveyance speed somewhat faster than the conveyance speed of the conveyance mechanism on the input side,
The veneer is pulled in a direction perpendicular to the fibers.
By using a tensioning means having a two-stage conveyance mechanism, that is, a conveyance mechanism on the carry-in side and a conveyance mechanism on the discharge side that is driven at a conveyance speed somewhat faster than the conveyance speed of the conveyance mechanism on the carry-in side. By applying a stable tensile force to the veneer caused by the difference in the conveyance speed of the two-stage conveyance mechanism, it is possible to reliably grow the scratches or cuts that have been formed in advance, and if necessary, it is possible to The practical effect of being able to stretch the veneer to an arbitrary ratio by changing the difference in the conveying speed between the conveying mechanisms on the side and the unloading side and changing the degree to which the veneer is pulled is extremely high.

That is, FIG. 1 is a side explanatory view for explaining the apparatus used to implement the method according to the present invention.

In the figure, reference numeral 1 denotes a cutting roller with a large number of sharp objects 2 such as knives attached to the circumferential surface in a continuous, discontinuous, or staggered manner in the axial direction.
3 is a support roller installed opposite to the cutting roller 1,
It constitutes a preforming means for forming a large number of scratches or cuts on the surface of the veneer 9 in advance.

A plurality of narrow rollers 4 are arranged at appropriate intervals in the axial direction, and constitute a transport mechanism on the input side of the transport means.

Reference numeral 7 denotes ring-shaped narrow rollers arranged alternately and intersectingly between the plurality of narrow rollers 4, and similarly, a plurality of narrow rollers 7 constitute a conveyance mechanism on the discharge side of the conveyance means. There is.

The plurality of narrow rollers 4 are connected via the main shaft 8, and the plurality of ring-shaped narrow rollers 7 are connected to the narrow rollers 4 via either one of the shafts 5 or 6 disposed on the outer periphery. The circumferential speed of the narrow roller 7 is somewhat faster than the circumferential speed of the rollers 7 and 7, respectively.

In other words, there is a conveyance mechanism on the carry-in side consisting of a plurality of narrow rollers 4, and a conveyance mechanism on the discharge side consisting of a plurality of ring-shaped narrow rollers 7 whose conveyance speed is higher than that of the narrow rollers 4. A plurality of rollers 4 and 7 on both sides are intertwined in an alternating manner to constitute a two-stage conveyance mechanism.

4a are arranged at appropriate intervals in the axial direction, and the main shaft 8a
A plurality of narrow rollers 7a are held by a plurality of narrow rollers 4a, and 7a is a plurality of narrow rollers 4a, which are arranged alternately and intersectingly between the plurality of narrow rollers 4a, and supported by shafts 5a and 6a. It is a ring-shaped narrow roller, and a single plate 9 is attached to the conveyance mechanism on the carry-in side and the conveyance mechanism on the discharge side, respectively.
The veneer support mechanism is arranged opposite to the two-stage transport mechanism through the passageway.

Reference numeral 10 denotes an unloading conveyor disposed behind the pulling means composed of the two-stage transport mechanism and the veneer support mechanism.

For example, if the veneer 9 is inserted into the apparatus configured as described above in a direction perpendicular to the fibers, the surface of the veneer 9 will be cut by the sharp object 2 attached to the cutting roller 1 constituting the preforming means. A flaw or cut is formed, and then, due to the difference in the conveying speed of the two-stage conveying mechanism of the tensioning means, a tensile force is applied to the veneer 9, causing it to crack at controlled intervals to cause said flaw or cut to grow. However, since a two-stage conveyance mechanism with different conveyance speeds is used as a pulling means, a stable tensile force is applied to the veneer to ensure that the scratches or cuts formed in advance grow. In addition to making it possible to form cracks, if necessary, the difference in the conveying speed of the two-stage conveying mechanism can be changed to change the degree to which the veneer is pulled, and the veneer can be stretched to an arbitrary ratio. It can also be stretched, and is much more effective than the case of stretching using a tensioning means using an elastic body, as exemplified in the explanation of the method according to the first invention.

As exemplified in the above embodiment, the interval between the positions of the two-stage transport mechanism on the loading and unloading sides that make up the tensioning means that contact the veneer is slightly larger than the interval between the scratches or cuts formed in advance. This setting is effective because the force for reliably forming tensile cracks can be concentrated on the scratches or cuts that have been formed in advance. A plurality of narrow rollers are arranged at appropriate intervals, and the transport mechanism on the unloading side is a plurality of narrow rollers arranged so as to intertwine alternately between the plurality of narrow rollers. If it is composed of rollers, it is easy to make each roller highly rigid and set the distance between the positions where they contact the veneer to be slightly larger than the distance between the scratches or cuts formed in advance. In any case, various preforming means similar to those described in the description of the method according to the first aspect of the invention can be used as the preforming means.

Furthermore, as mentioned in the explanation of the method according to the first invention, the effects of variously changing the form of the scratches or cuts formed in advance, or variously changing the form of applying tension, are as follows:
This method is the same as that described in the description of the method according to the first invention, and of course it is also possible to apply this method to the implementation of the method according to the second invention.

As is clear from the above, according to the method of the present invention, it is possible to stably form a large number of cracks with an appropriate spread at approximately desired intervals in a veneer, thereby reducing the thickness of the veneer and the strength of the plywood. While avoiding cracks, it is possible to eliminate cracks in the veneer, homogenize it, prevent overlapping, improve yield, and improve plywood quality. is extremely large.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIG. 1 is a side explanatory view for explaining the apparatus used to carry out the method according to the present invention, and FIGS. FIG. 3 is an explanatory plan view of a veneer with scratches or cuts. FIG. 3 is an explanatory plan view of a veneer with many cracks. 1... Cutting roller, 2... Sharp object, 3
... Support roller, 4 ... Narrow roller, 7 ... Ring-shaped narrow roller, 9, 11,
12,13...Single board, 14.16...
Scratch or cut, 15...Crack.

Claims (1)

[Scope of Claims] 1. Using an appropriate preforming means equipped with a sharp object such as a knife or a heating source, a large number of scratches or cuts are made in advance on the surface of a veneer veneer, so that the fibers of the veneer veneer are forming them at arbitrary intervals in the orthogonal direction, and then stretching or bending the veneer veneer in the direction orthogonal to the fibers using a suitable tensioning or bending means to grow the previously formed flaws or incisions; A method for forming cracks in a veneer veneer, characterized by forming cracks at controlled intervals. 2. Using an appropriate preforming means equipped with a sharp object such as a knife or a heating source, a large number of scratches or cuts are made in advance on the surface of the veneer veneer at arbitrary intervals in the direction orthogonal to the fibers of the veneer veneer. When forming the veneer separately, the spacing in the direction perpendicular to the fibers near the edges in the fiber direction is smaller than the distance in the direction perpendicular to the fibers in the center of the veneer veneer in the fiber direction. and then, using suitable tensioning or bending means, pull or bend the veneer perpendicular to the fibers to grow said preformed scars or incisions at controlled intervals. A method for forming cracks in a veneer veneer, characterized by forming cracks. 3. Using an appropriate preforming means equipped with a sharp object such as a knife or a heating source, a large number of scratches or cuts are made in advance on the surface of the veneer veneer at arbitrary intervals in the direction orthogonal to the fibers of the veneer veneer. forming cracks at controlled intervals by forming the veneer at controlled intervals and then using suitable tensioning means to pull the veneer veneer in a direction perpendicular to the fibers to grow said pre-formed flaws or cuts; A veneer sheet is produced by using a tensioning means having a two-stage conveyance mechanism, that is, a conveyance mechanism on the carry-in side and a conveyance mechanism on the discharge side that is driven at a conveyance speed somewhat higher than the conveyance speed of the conveyance mechanism on the carry-in side. A method for forming cracks in a veneer veneer, characterized by pulling the board in a direction perpendicular to the fibers.