JP3109999B2 - Method of fixing compressed state of wood material molded article and method of removing residual stress of wood material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying wood, in which the shape and volume of a wood material temporarily formed by compression can be maintained for a long period of time while resisting changes in humidity and temperature. Thus, the present invention relates to a method for fixing a compressed state. Another aspect of the present invention relates to a method for removing stress remaining in a log or sawn sawn timber using the above-described compression state fixing technique.

[0002]

2. Description of the Related Art In order to improve the physical properties of wood, a reforming treatment for compressing a wood material in a softened state to increase the density has been known for a long time and has been industrially put to practical use. However, simply compressing softened wood leaves the compressive stress generated during the molding process.If the molded product is heated above its softening point, the temporarily fixed compression state will change to the residual stress. It is destroyed by the action, the volume of the compressed wood recovers to near the volume before compression (referred to as volume relaxation), and the shape is expanded to a state close to the shape before compression.

For practical use of compressed wood, therefore, it is important to fix the compressed state by removing the stress. Conventionally, as an effective method for semi-permanently fixing the compressed state of compression-molded wood, a temporary method has been proposed. 20 while maintaining the compressed state
Dry heating at 0 ° C or higher or wet heating at around 180 ° C,
That is, it is known to perform heating using steam or the like. For example, JP-A-3-231802 discloses that wood softened in high-temperature and high-pressure steam is compressed between a pair of molds under high pressure or normal pressure to be compression-molded into a polygonal column shape and the like. A technique has been disclosed in which the shape is fixed again by leaving it in high-temperature steam for a certain period of time.

However, in the above-mentioned prior art, the compressed wood must be kept in a pressurized state in the mold until the fixing is completed, so that the residence time in the mold becomes longer. This lowers the operating rate of expensive molds and increases the cost of products.

[0005] In addition, the stress generated during the growth process of natural standing trees remains in logs and lumber. When the temperature becomes high during use, the log and lumber are distorted by the action of the stress. This is a fatal defect when solid wood is used as a structural material, and there has been no effective countermeasure except for long time and sufficient drying before lumbering.

[0006]

SUMMARY OF THE INVENTION The present invention provides a new, simple, and economical method for fixing a compressed state of compressed wood, in which a temporarily fixed state of compressed wood is fixed without using a mold. Make it an issue. Further, the present invention uses a new, simple, and simple method for removing growth stress remaining in a log or lumber or residual stress after bending without causing a change in the shape of a wooden material using the same technique as described above. It is an object to provide an economical stress removing method.

[0007]

The first method of the present invention comprises:
A wooden material molded product having a shape temporarily fixed by compression and heat-resistant hard particles are placed in a container, and the particles are heated in a state in which the particles are tightly filled between the molded products and a gap between the container and the container. This is a method for fixing a compressed state of a wooden material molded product. Here, the temporarily fixed shape refers to the shape held by the compressed wood and the volume under the compressed state in a state where the softened wood is compressed and molded by a mold or the like. The immobilization in the compressed state means that the temporarily immobilized size, shape, volume, the state in which the internal structure of the conduit, the pair of bounded wall holes or the cell lumen, etc. is compressed is applied to the compressed wood. Permanent so that it can withstand changes in humidity and temperature and keep it semi-permanently.

[0008] In the second method of the present invention, a log or sawn timber and heat-resistant hard particles are placed in a container.
A method for removing residual stress in a log or lumber, characterized in that the particles are heated in a state of being closely packed between the log or lumber and the gap between the log and lumber and the container.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a wood material molded product whose shape is temporarily fixed is a product obtained by compressing so-called lumber such as a prism, a rectangular bar, a cylinder, a thick plate, and a product obtained by compressing a log. Is included.

In the present invention, compression for temporarily fixing the shape can be performed by a method known in the art. For example, soft softwood lumber and logs are softened to 10
After being heated and softened in steam or air at a temperature of about 0 ° C, it is mechanically compressed between a pair of dies, and the dies and molded products are cooled while maintaining the compressed state to form temporarily. Is immobilized. Alternatively, a log dried to near the fiber saturation point is waterproofed, immersed in hot water, heated to 95-100 ° C. and softened, and then the water pressure of the hot water is increased by 10-30 with a pump or the like.
The pressure is increased to kg / cm ² and then cooled while maintaining the pressure by a method such as switching hot water to cold water to obtain a molded article having a chopped log tone.

The heat-resistant hard particles used in the present invention are natural sand having a relatively uniform particle size, or inorganic fine particles such as synthetic silica and synthetic alumina. The heat resistance is such that it does not soften near the operating temperature of the heat treatment described later, for example, 3
Any heat resistance of about 00 ° C. is sufficient. Practically, commercially available alumina abrasives can be exemplified.

The particle size of the hard particles varies depending on the shape and surface accuracy of the molded product, but as described in the second aspect of the present invention, the average particle size is preferably 0.3 mm to 4 mm. Especially 0.3
The range of mm-3 mm is easy to use. Plate materials requiring surface smoothness, squeezed log-like molded products using fine wrinkles on the side compressed by hydrostatic pressure as decorative appearance, etc., preferably have a fine particle size, but the average particle size is less than 0.3 mm In this case, it is difficult to remove the particles after the completion of the fixing treatment, which is not preferable. When manufacturing a compressed log for lumber which performs lumbering after consolidation, it is easy to use a log with an average particle diameter of 2 mm to 3 mm. 4
If the particle size exceeds mm, the surface of the molded article becomes rough, and it becomes difficult to transport the hard particles in and out of the container by air.

The shape and dimensions of the container used in the present invention are not particularly limited, but may be any as long as they can store one or a plurality of molded wood materials. Usually, a cylindrical container having a sufficient length to be used for immobilizing a rectangular column or other long material is practical. It is convenient if one closed bottom of the cylindrical shape is provided with a hole for discharging particles and a valve, and the other bottom is provided with an opening / closing lid for insertion and removal of wood material.

Regarding the pressure resistance of the container, for example, if the container is made of a normal steel plate, no special pressure resistance is required. The reason is that, for example, when the expansion force of a long wooden material molded product is directly confined by a mold, a strong bending stress is applied to the mold, so that a thick wall is required. By considering the relative position of the material molded article, the hard particles interposed between the container wall and the molded article equalize the expansion force and transmit the same to the container wall. As a result, the expansion due to the tensile strength of the container wall occurs. It is because it can hold down power.

In the present invention, when a wooden material molded article is housed in the container, a space is provided so that the hard particles are sufficiently surrounded and filled around the molded article, that is, by using a spacer, for example. It is necessary to ensure a gap between the wall and the molded article and also a gap between the wooden material molded articles. This gap depends on the shape and the particle size of the hard particles, but a general standard may be about several cm.

In the present invention, the hard particles need to be densely packed so as to form a so-called densely packed state. Here, the dense packing means that the particles are no longer simply gently poured into the gap but are completely filled without leaving any space by an operation such as applying vibration to the container, and the wooden material molded product is easily manufactured. The porosity is reduced as much as possible by filling the particles so that they do not move in the radial direction of the container. This state is called regular close-packing if the particles are spherical particles having the same diameter.However, in the present invention, particles having a non-spherical shape and a particle size distribution may be used. It is a state called.

As described in the third aspect of the present invention, the means for realizing the tightly packed state includes a method of adding particles while oscillating the whole container after the particles are injected, and a method of forming a wood material after the particles are injected. A method of adding particles while vibrating the product or container wall manually or mechanically, and a method of additionally injecting particles while vibrating the particles by inserting a vibrating rod into the injected particles, and the like. .

After the particles are densely packed in the container, the opening and closing lid of the container is closed to hold down the particles inside. However, if necessary, instead of the opening / closing lid, it may be held by a wire mesh that does not allow particles to pass through, and air expanded during the heat treatment described later or water vapor generated may be freely passed by a pressure difference. When the layer of the particles covers the upper end of the molded product in the axial direction in the container, the lid for holding the particles is not necessarily required. As described above, since the necessity of the lid varies depending on the shape of the wooden material molded article, the degree of compression of the compression molding, the relative size of the container and the molded article, the lid of the container is not a necessary requirement in the present invention.

Next, in the method of the present invention, the wooden material molded article is heat-treated in a state where the hard particles are densely packed. As described in the fourth aspect of the present invention, the heat treatment is performed by heating to a temperature of 180 to 250 ° C. by dry heating or to 140 to 190 ° C. by wet heating. For the dry heating, a method usually used in the art can be used. Practically, external heating by a flame, feeding of hot air in a hot air dryer, a heating medium, electric heating, microwaves and the like can be exemplified. Examples of the wet heating include feeding of high-temperature and high-pressure steam by a steam pot commonly used in the art, feeding of hot water, and the like.

The heating time varies depending on the heating temperature, the desired degree of immobilization, the partial pressure of water vapor in the atmosphere, the thickness of the molded product, and the like, and cannot be specified unconditionally.
00 minutes are used. However, longer heating times may be desirable for some products.

By performing the above heat treatment, the compressed state of the compression molded wood material molded article is fixed, so that the high temperature particles are extracted from the container by vibration, or the naturally cooled particles are extracted by vibration, Take out the molded product.

The degree of fixation of the compressed state (degree of fixation)
When the molded article after the immobilization is treated with hot water for a predetermined time, for example, at 95 ° C. for 60 minutes, it is expressed by a recovery rate of the cross-sectional area reduced by compression or the percentage of the thickness in the compression direction. The recovery rate may be slightly higher when the molded article is used in a dry atmosphere indoors, but a lower recovery rate is required for applications that are exposed to steam, dew, or rainwater.

The present invention is practically widely applied to soft conifers such as cedar, karamatsu, cypress, bay pine, bay toga, but is not basically limited by tree species.

Next, according to the fifth aspect of the present invention, a log cut from a standing tree or a lumber such as a square pillar obtained by cutting the tree and used without compression is stored in the container while maintaining an appropriate gap. Then, the heat-resistant hard particles are densely packed by vibration or the like, and heated to 70 to 150 ° C. for about 1 to 100 hours using, for example, high-pressure steam in the tightly packed state. After the completion of the heat treatment, it is also possible to switch to high-pressure air and appropriately dry the log or lumber while also cooling the inside of the container. After the heat treatment, the particles are discharged from the container by vibration, and the product is taken out.

[0025]

EXAMPLES The present invention will be described in more detail with reference to Examples, but it should not be construed that the invention is limited thereto. Here, unless otherwise specified, the degree of fixation is represented by the recovery rate defined above.

[Example 1] Manufacture of a wooden material molded product (1) dimensions 900 mm (L) x 50 mm (R) x 150 mm
(T) Put the cedar mesh material with a moisture content of 23% into a steam kettle,
After steaming for 60 minutes in a steam atmosphere of kg / cm ² ,
It was taken out into the atmosphere and compressed to a radial thickness (R) of 22 mm by two opposing hot plates adjusted to 120 ° C.
Then, while being pressed, cooling water is circulated through a pipe built in the hot platen to cool the internal temperature of the compressed wood to 30 ° C. or less, and the wooden material molded product (1) in which the compressed state is temporarily fixed is obtained. Obtained. The peripheral part is cut and removed from this molded product, and 300 mm (L) × 22 mm (R) × 102 mm (T)
1 was cut out, and as shown in FIG. 1, three points A, B, and C in the tangential direction (T) of the wood, and 1 in the fiber direction (L).
A total of nine grid-like measuring points, three and two, were selected, and the dimensions in the radial direction (R) were measured. The results are shown in Table 1.

Closely packed with hard particles A cylindrical container body having an inner diameter of 105 mm × 400 mm (L) is provided with a flange-type lid (with air permeability) attached to both ends of a cylindrical container body so that the test piece does not come into contact with the container wall. Stored in
As heat-resistant hard particles, pulverized fused alumina having an average particle size of 0.5 mm (Morundum A-40, No. 3 manufactured by Showa Denko KK)
6) was filled completely, and the lid was closed. Next, hit the container with a hammer to apply vibration, tighten the bolt and nut on the lid,
This was repeated until the filling gap disappeared and the lid could not be retightened.

Heat treatment The above vessel is put in a high-pressure steam pot, steamed at 175 ° C. for 1 hour and heated, then the steam pot is gradually depressurized to normal pressure, the vessel is naturally cooled, and a test piece is taken out of the vessel. Then, a test piece as a molded article (1) subjected to the immobilization treatment was obtained. For this test piece, the dimension in the radial direction (R) at the measurement point was measured, and the results are shown in Table 1. The change in the radial dimension due to the immobilization treatment was extremely small. In addition, the weight of the molded article decreased by 5.8%.

Measurement of degree of immobilization A test piece as a molded article (1) after the above-mentioned immobilization treatment was heated to 95 ° C.
After being immersed in hot water kept at 60 ° C. for 60 minutes, it was dried in a hot air dryer at 105 ° C. for 3 days to make it completely dry. Table 1 shows the results of measuring the thickness of the test piece in the radial direction (R) at the nine measurement points and calculating the recovery rate by the following equation. The test specimens with the compressed state fixed were not dried to the absolute dry state, whereas the test specimens after hot water treatment were dried to the absolute dry state and the thickness was measured. , But actually indicates that the immobilization was completely completed.

[0030]

[Formula 1] t ₀ : Thickness before compression molding t ₁ : Thickness after fixing in a compressed state t ₂ : Thickness after hot water treatment / drying

[0031]

[Table 1] ─────────────────────────────────── Measurement point Compression molded product After fixation Fixation treatment the hot-water treated product recovery rate thickness thickness t ₁ the rate of change (%) thickness t ₂ (%) ───────────────────────────── Ａ A1 21.6 21.9 1.4 21.2 -2.5 2 21.9 22.6 3.2 22.3 -1.1 3 21.7 22.3 2.8 22.0 -1.1 B1 22.5 22.2 -1.3 22.1 -0.3 2 22.4 22.7 1.3 22.5 -0.7 3 22.2 21.8 -1.8 21.5 -1.1 C1 21.9 21.9 0 21.3 -2.1 2 21.7 22.5 3.7 22.0 -1.8 3 21.5 22.5 4.7 22.0 -1.8 ───────────────────────────── ────── (Note) Unit of thickness: mm, t ₀ = 50 mm

[Example 2] Production of a wood material molded article (2) A cedar log with bark having a diameter of about 170 mm and a length of 950 mm, which had been dried, was put into a high-temperature dryer, and the steam pressure was set at 1 kg.
/ Cm ² at a temperature of 101-105 ° C. for 2 days,
A dried log having an average moisture content of 37% by weight was obtained. A chloroprene-based adhesive (manufactured by Konishi Co., trade name: Bond G)
17) was applied, and a commercially available wrap film made of polyvinylidene chloride was stuck thereon to prevent water from permeating through the kiguchi.
After heating this log in a hot air oven at 90 ° C. for 2 hours, 95%
The mixture was placed in a vertical cylindrical hermetic kettle filled with hot water at ℃, and 2 liters of cold water per minute was injected from the bottom of the kettle with a pump. The pressure in the kettle reached 30 kg / cm ² in about 5 minutes, the relief valve previously provided on the top of the kettle was activated at this time, and thereafter the injection of cold water was continued while the internal pressure was maintained at 30 kg / cm ² . The temperature of the water discharged from the valve is 30 ° C in 15 minutes
It fell below. After the cold water injection was further continued for 90 minutes, the kettle was opened and the log was taken out. The xylem of the log was considerably compressed and the bark could be easily removed. Put this log in the air
It was left to stand for a week and air-dried to obtain a wooden material molded product (2) which was compressed wood. The molded product had a so-called squeezed log-like appearance with complicated irregularities on the surface. The cross-sectional shape of both lips was copied on paper, and the area was measured.
Was decreasing.

Immobilization treatment The wood material molded product (2) is vertically divided, the cut surface is planarized, and cut into 220 mm in length to obtain FIG.
Specimens having the cross-sectional shape shown in Table 1 were prepared, the cross-sectional shape was copied on paper, and the cross-sectional area was measured. The character A displayed at the tip of the figure is a sign indicating that this tip is the original one of the two tips. Next, using the same container and hard particles as in Example 1, the above-described specimen and particles were filled in the same manner as in Example 1. This container was placed in the same high-pressure steam kettle as in Example 1, and a test body as a molded article (2) similarly fixed was obtained. The cross-sectional shape of this test body after the immobilization treatment was copied onto paper in the same manner as described above, and the same original port as above was compared. As a result, as shown in FIG. However, the cross-sectional area was reduced by 1.6% by the immobilization treatment. That is, although the molded article (2) was heated for fixing the compressed state, the volume relaxation did not occur, and it was proved that the molded article (2) did not expand. Further, when the weight was measured, the weight was reduced by 5.4% due to the immobilization treatment.

Measurement of the degree of immobilization Using the test body after the immobilization treatment, 9
After hot water treatment at 5 ° C., it was dried in a hot air drier at 105 ° C. for 3 days to make it completely dry, and the cross-sectional area of the base was measured in the same manner as described above. The cross-sectional area did not change at all by the hot water treatment. Therefore, the recovery rate calculated by the following equation was 0%.

[0035]

[Formula 2] s ₀ : cross-sectional area before compression molding s ₁ : cross-sectional area after fixing in a compressed state s ₂ : cross-sectional area after hot water treatment and drying

[0036]

When the method of the present invention is applied to compressed wood having a desired cross-sectional shape, an expensive mold is used only for a short time to form softened wood, and thereafter requires a long time. The immobilization of the compressed state is performed by removing the wooden material molded product from the mold. Therefore, productivity per mold occupation time is significantly improved.

According to the method of the present invention, even a compression-molded product having a complicated appearance such as a round log tone can be easily filled with hard particles, so that the external shape can be easily fixed without applying a high pressure. it can.

In the method of the present invention, since the frictional force of the densely packed particles exerts an action of absorbing the expanding force of the wood, the container need only have low pressure resistance, and a low-cost apparatus having a thin wall can be used. Can be used.

According to the method of the present invention, since the densely packed particles can pass through the fluid, efficient heating can be achieved by the flow of steam. If superheated steam is used, the molded product can be dried while fixing the compressed state, and a wooden material molded product can be economically manufactured.

According to the second aspect of the present invention, logs and lumbers whose shapes are unlikely to be deformed by temperature and humidity can be easily produced with high productivity without naturally drying the raw wood for a long period of time.

[0041]

[Brief description of the drawings]

FIG. 1 is a plan view showing measurement points on a grain of a test piece for measuring an effect of the present invention for a wooden material molded article (1).

[0042]

FIGS. 2A and 2B are cross-sectional views of a base of a specimen for showing the effect of the present invention with respect to a wooden material molded article (2), in which (a) is before fixing in a compressed state, and (b) is fixed in a compressed state. Later.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-231802 (JP, A) JP-A-4-201503 (JP, A) JP-A-5-50409 (JP, A) JP-A-6-206 91611 (JP, A) JP-A-8-155910 (JP, A) JP-A-8-224709 (JP, A) JP-A 8-276407 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B27K 5/00 B27K 5/06

Claims (6)

(57) [Claims] 1. A wooden material molded article whose shape is temporarily fixed by compression and heat-resistant hard particles are placed in a container, and the particles are tightly filled between the molded articles and the gap between the container and the container. A method for fixing a compressed state of a wooden material molded article, comprising heating. 2. The heat-resistant hard particles have an average particle size of 0.3-4.
2. The method for fixing a compressed state according to claim 1, wherein the diameter is mm. 3. The method for fixing a compressed state according to claim 1, wherein the heat-resistant hard particles are densely packed using a vibration means. 4. The heat treatment is performed by 180-250 by dry heating.
The method for fixing a compressed state according to claim 1, wherein the method is performed at 140 ° C. or 190 ° C. by wet heating. 5. A method in which a log or a sawn sawn timber and heat-resistant hard particles are placed in a container, and the particles are heated in a state of being tightly packed between the log or the sawn timber and a gap between the log and the container. Characteristic method for removing residual stress from logs or lumber. 6. The method according to claim 5, wherein heat treatment is performed at 70 to 150 ° C. using heat-resistant hard particles having an average particle diameter of 0.3 to 4 mm.