JP2004358880A - Method and equipment for manufacturing woody fiber mixed cement board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and equipment for manufacturing a woody fiber mixed cement board of which the coarse and heavy materials are prevented from being exposed on the surface and which has the smooth and beautiful surface and causes no nonuniformity of coating. <P>SOLUTION: A roller 47 for leveling the materials classified by a sieve 43 and having large grain sizes is disposed on the downstream side just under the lower end of the sieve 43. Even when the materials having the large grain sizes and classified by the sieve are scattered and accumulated in such a manner that they stick in, they are leveled by the leveling means disposed just under the lower end of the sieve and then the materials classified by the sieve and having small grain sizes are scattered and accumulated on the surfaces of the leveled materials. The materials are pressed and cured thereafter by placing an upper form plate and thereby the woody fiber mixed cement board having the smooth surface is obtained. By this solution, no nonuniformity of coating occurs when the coating is made, and the woody fiber mixed cement board having excellent water resistance and freeze resistance can be manufactured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a wood fiber-mixed cement board having excellent smoothness and an apparatus for producing the same.
[0002]
[Prior Art and Problems to be Solved by the Invention]
In general, a wood fiber-mixed cement board widely used as an exterior material and a base material is obtained by pressing a mixture containing cement and wood fiber as main raw materials and curing and curing the mixture.
That is, a mixture obtained by mixing raw materials such as cement, wood fiber and aggregate is dropped in a forming chamber, and the mixture is scattered and deposited on a lower mold plate conveyed by a conveyor belt to obtain a deposit. Thereafter, an upper die plate was placed thereon, pressed and cured to cure, thereby producing a wood fiber mixed cement plate.
[0003]
Conventionally, as a method of manufacturing a cement board mixed with wood fiber, for example, there is a method of manufacturing a hard wood chip cement board (see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-10-231160 (FIG. 1)
[0005]
That is, when the mixture is dropped and sprayed, when the mixture is blown along the transport direction and air is classified by a sieve, coarse and heavy raw materials are dropped and deposited directly below the lower end of the sieve, and the raw material is dropped thereon. This is a manufacturing method in which a fine and light raw material that has passed through a sieve and is deposited can be obtained.
[0006]
However, in the above-mentioned method for manufacturing a hard wood chip cement board, the coarse and heavy raw material dropped just below the lower end of the sieve is scattered and deposited while piercing the surface of the deposit deposited in the previous step. For this reason, even if a fine and light raw material is sprayed on the coarse and heavy raw material in a pierced state, the coarse and heavy raw material, for example, a piece of wood, aggregate, etc., is exposed on the surface, and the protrusion due to the wood piece or the like and the falling off of the wood piece, etc. Recesses occur. As a result, a smooth and beautiful hard wood chip cement board cannot be obtained. In particular, when the hard wood chip cement board is coated, not only coating unevenness is likely to occur but also desired water resistance and frost damage resistance cannot be obtained. There was a problem.
[0007]
In view of the above problems, an object of the present invention is to provide a method for producing a wood fiber-mixed cement board having a smooth and beautiful surface and free from uneven coating, and an apparatus for producing the same.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing a wood fiber-mixed cement board according to the present invention is to drop a mixture mainly composed of cement and wood fiber in a forming chamber, classify the mixture with a sieve, and classify the mixture with the sieve. After the raw material having the particle size is scattered and deposited from the lower end of the sieve on the lower die plate to be conveyed, the raw material having the small particle size classified by the sieve is leveled by a leveling means arranged immediately below the lower end of the sieve and arranged on the downstream side. The upper mold plate is placed on the sediment obtained by spraying and accumulating, and is pressed and cured to cure and harden.
[0009]
According to the present invention, even if the raw material having a large particle size classified by a sieve is scattered and deposited so as to pierce, the raw material is classified by a sieve on a surface thereof after being leveled by a leveling means arranged immediately below a lower end of the sieve. Since the material having a small particle size is scattered and deposited, a cement board mixed with a wood fiber having a smooth surface and a beautiful appearance can be obtained. Therefore, even when the wood fiber-mixed cement board according to the present invention is coated, coating unevenness does not occur, and a wood fiber-mixed cement board having excellent water resistance and frost damage resistance can be obtained.
[0010]
In addition, in order to achieve the above-mentioned object, the manufacturing apparatus of the wood fiber-mixed cement board drops a mixture containing cement and wood fiber as main raw materials in a forming chamber, classifies the mixture with a sieve, and classifies the mixture with the sieve. After scattered and deposited from the lower end of the sieve on the lower die plate where the raw material is conveyed, the upper die plate is placed on the sediment obtained by scattered deposition of the raw material having a small particle size classified by the sieve, and pressed, In the apparatus for manufacturing a wood fiber-mixed cement board produced by curing and curing, even in a configuration in which a leveling means for leveling a raw material having a large particle diameter classified by the sieve is disposed on the downstream side immediately below the lower end of the sieve. Good.
[0011]
According to the present invention, a raw material having a large particle diameter that is scattered and deposited by a leveling means disposed immediately below a lower end of a sieve to pierce the raw material, and a raw material having a small particle diameter classified by a sieve is scattered on the surface thereof. Therefore, a wood fiber mixed cement board having a smooth surface and a beautiful surface can be obtained. Therefore, even when the wood fiber-mixed cement board according to the present invention is coated, coating unevenness does not occur, and a wood fiber-mixed cement board having excellent water resistance and frost damage resistance can be obtained.
[0012]
In an embodiment of the present invention, the leveling means may be a roller or a scraper.
According to the present embodiment, after the raw material having a large particle diameter scattered and deposited so that a roller or a scraper pierces, the raw material having a small particle diameter classified by a sieve can be scattered and deposited on the surface thereof, so that the surface is smooth and beautiful. There is an effect that a natural wood fiber mixed cement board can be obtained.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments and examples according to the present invention will be described with reference to the accompanying drawings of FIGS.
As shown in FIG. 1, the present embodiment includes four first, second, third, and fourth forming chambers 10 above a lower mold plate 51 conveyed in the direction of arrow A by a conveyor belt 50. This is a case where 20, 30, and 40 are sequentially arranged, and the mixture 11, 21, 31, and 41 is applied to a manufacturing apparatus that sequentially scatters and deposits the mixture.
[0014]
The first forming chamber 10 has a sieve 13 inclined below the downstream end of a supply conveyor belt 12 that transports the mixture 11 in the same direction as the transport conveyor belt 50. The sieve 13 is disposed between an air discharge port 15 and an air discharge port 16 of a blow duct 14 that blows air in a direction opposite to the transport direction.
[0015]
The second forming chamber 20 naturally drops the mixture 21 from the downstream end of the supply conveyor belt 22 that transports the mixture 21 in the same direction as the transport conveyor belt 50, and scatters and deposits the mixture 21 on the lower mold plate 51.
[0016]
The third forming chamber 30 naturally drops the mixture 31 from the downstream end of the supply conveyor belt 32 that conveys the mixture 31 in a direction opposite to the conveyance conveyor belt 50, and scatters and deposits the mixture 31 on the lower mold plate 51.
The fourth forming chamber 40 has a sieve 43 inclined below the downstream end of a supply conveyor belt 42 that transports the mixture 41 in a direction opposite to the transport conveyor belt 50. The sieve 43 is disposed between an air discharge port 45 of an air duct 44 that blows air in the transport direction and an air discharge port 46. Further, a roller 47 as a leveling means is disposed immediately downstream of the lower end of the sieve 43.
[0018]
The mixture 11, 21, 31, 41 uses the same material mainly composed of cement and wood fiber.
That is, the cement is not particularly limited, and examples thereof include Portland cement, blast furnace cement, silica cement, fly ash cement, and alumina cement. Further, a siliceous material may be added to improve the reactivity. This includes, for example, quartz sand, quartzite powder, diatomaceous earth, silica fume, fly ash and the like.
[0019]
And in the wood fiber mixed cement board of the present invention, the cement is added in the range of 50% by weight to 70% by weight, and the siliceous material is added in the range of 0% by weight to 20% by weight.
[0020]
The wood fiber is not particularly limited, but for example, wood chips such as cedar and pine and crushed waste wood can be used alone or in combination.
[0021]
Preferably, the wood fibers have a size that allows them to pass through a sieve having an aperture of 4 mm. This is because if wood fibers of a size that cannot pass through a sieve having a mesh size of 4 mm are mixed, that portion becomes a weak point and the peel strength decreases. Further, the wood fiber is preferably a flat one having an average thickness of 0.5 mm.
[0022]
The wood fiber is added in the range of 8 to 30% by weight, and in particular, the addition amount of the wood fiber in the surface portion is preferably 8 to 14% by weight. If the amount of the wood fiber is less than 8% by weight, the surface becomes too dense and becomes too hard, which makes nailing difficult, and becomes brittle, so that chipping or cracking is likely to occur at the time of nailing. On the other hand, if the content exceeds 14% by weight, the amount of wood fiber becomes too large, the surface property is deteriorated, and the proportion of cement is reduced. For this reason, the bonding force between the wood fibers is weakened, the strength is reduced, and the nail holding force is reduced, which causes a problem that chipping or cracking tends to occur when nailing.
[0023]
In addition, the said surface part, if it is a wood fiber mixed cement board with a total thickness of 10 to 30 mm, a surface layer having a thickness of 1/4 to 1/40 from the surface and a density of substantially the same is considered. Say. The thickness dimension of 1/4 is the maximum thickness dimension which can be formed to 8 to 14% by weight of the entire wood when one of the surfaces is formed by four forming chambers. It is about 7.5 mm. On the other hand, the thickness dimension of 1/40 is the minimum thickness dimension that allows the entire surface portion to be formed to a wood mass of 8 to 14% by weight when a thin layer is formed as a surface portion in a forming chamber. Is about 0.3 to 0.8 mm.
[0024]
A lightweight aggregate may be added as an admixture to reduce the specific gravity of the wood fiber-mixed cement board. For example, perlite, shirasu balloon, glass balloon and the like can be mentioned, and these can be used alone or in combination. The lightweight aggregate is added in a range of 0% by weight to 25% by weight.
[0025]
Further, as an additive to be added to the cement board mixed with wood fiber, for example, a hardening accelerator such as magnesium chloride, magnesium sulfate, calcium chloride, sodium aluminate, potassium aluminate, aluminum sulfate, water glass, vermiculite, bentonite, etc. Mineral powders, water repellents such as wax, paraffin, silicon, etc., reinforcing materials such as synthetic resin emulsions, expandable thermoplastic plastic beads, plastic foams and the like can be used as necessary.
[0026]
As a method of obtaining the mixture by mixing the cement, the wood fiber, the aggregate, the additive, and the water, the mixing may be performed using an existing machine, and the mixing method is not particularly limited.
[0027]
Next, a manufacturing method using the manufacturing apparatus having the above configuration will be described.
That is, the conveyor belt 50 is moved in the direction of arrow A to convey the lower mold plate 51. On the other hand, the mixture 11 is dropped on the driven supply conveyor belt 12, transported to the downstream end, and dropped on the inclined sieve 13. At this time, the air discharge port 15 of the air duct 14 blows air to sifte the mixture 11. For this reason, of the sieved mixture, the fine and light raw material is deposited on the lower plate 51 on the upstream side, and then the coarse and heavy raw material is deposited on the lower plate 51 on the downstream side, so that the deposit 53 is obtained. As a result, the finest and lighter material is first deposited on the lowermost surface of the deposit 53, and a dense surface portion is formed. In addition, even if a coarse and heavy raw material falls so as to pierce the lower mold plate 51, the lower mold plate 51 becomes a reference surface, and a wood fiber-mixed cement board with less unevenness can be obtained.
[0028]
Further, the mixture 21 having the same composition as described above is dropped on the supply conveyor belt 31 of the second forming chamber 20, conveyed to the downstream end, and allowed to fall naturally to be scattered and deposited.
[0029]
Similarly, the mixture 31 having the same composition as described above is dropped on the supply conveyor belt 32 of the third forming chamber 30, conveyed to the downstream end, and dropped naturally to be scattered and deposited.
[0030]
Next, the mixture 41 having the same composition as described above is dropped onto the supply conveyor belt 42 of the fourth forming chamber 40, transported to the downstream end, and dropped on the inclined sieve 43. At this time, air is blown from the air discharge port 45 of the air blow duct 44, and the mixture 41 is sieved. Therefore, of the sieved mixture 41, a coarse and heavy raw material is deposited just below the lower end of the sieve 43. At this time, even if the coarse and heavy raw material is deposited so as to pierce the sediment, the roller 47 smoothes the coarse and heavy raw material of the sediment 53 evenly, and the fine and light raw material is sprayed on the surface of the smoothed coarse and heavy raw material. Is deposited. For this reason, the finest and lightest raw material is deposited on the uppermost surface of the deposit 53, and the deposit 53 having a dense surface portion on the front and back surfaces is obtained.
[0031]
It is preferable that the wood mass of the surface portion of the sediment 53 is 8 to 14% by weight, and the density of the surface portion is +0.05 to -0.1 g / cm ³ than the density of the inner portion. In particular, when the density difference exceeds + 0.05 / cm ³ and the surface portion becomes dense, the surface portion is easily peeled, and the density difference exceeds -0.1 g / cm ³ and the internal portion becomes dense. In such a case, the surface strength is weakened, the nailing property is deteriorated, and the surface property is also deteriorated.
[0032]
In order to secure the desired density difference as described above, the speed at the air discharge port of the wind blown for sieving the mixture is preferably in the range of 10 to 20 m / sec. If the wind speed is less than 10 m / sec, coarse and heavy wood fibers and the like are distributed on the surface to deteriorate the surface properties. If the wind speed exceeds 20 m / sec, the surface becomes too dense and hard, resulting in nailing. This is because it becomes difficult and peeling becomes easy.
[0033]
Then, an upper mold plate (not shown) provided with a surface pattern is placed on the upper surface of the deposit 53, and the deposit 53 is pressed and clamped by the upper mold plate and the lower mold plate 51, and then cured and cured. A wood fiber mixed cement board is obtained.
[0034]
Curing and curing is a process in which the cement is cured to bond and integrate the wood fibers, and conventional methods such as steam curing and autoclave curing can be used.
[0035]
The mixture may be scattered and deposited by blowing air in all steps, or may be performed without blowing air in all steps. In addition, the classification of the mixture is not limited to the case where the air is blown, and the classification may be performed, for example, by vibrating the sieve itself. Furthermore, at least one forming chamber may be used, and four or more forming chambers may be used.
[0036]
In the present invention, the present invention is not limited to the case where one kind of mixture is scattered and deposited. For example, two kinds of mixtures containing two kinds of wood fibers having different sizes are blown or not blown. May be sequentially formed to form a deposit having a surface portion and an inner portion having different densities.
[0037]
Further, the wood fiber-mixed cement board of the present application preferably has an overall density in the range of 0.7 to 1.3 g / cm ³ . If the density is less than 0.7 g / cm ³ , sufficient strength as the outer wall material cannot be obtained. If the density exceeds 1.3 g / cm ³ , the workability is poor due to being too heavy.
[0038]
【Example】
(Example 1)
50% by weight of cement, 15% by weight of wood fiber, 20% by weight of silica powder as a siliceous raw material, and 15% by weight of perlite as an admixture are mixed with a mixer to obtain a dry mixture. Then, 40% by weight of water is added to the dry mixture. % To obtain a wet mixture. Next, the wet mixture was spray-deposited on the lower mold plate 51 using a manufacturing apparatus having the same structure as the manufacturing apparatus shown in FIG.
[0039]
In particular, in the fourth forming chamber 40, the material is leveled by a roller 47 having a diameter of 100 mm, fine and light materials are scattered and deposited, and then an upper mold plate (not shown) is placed thereon, and the deposit is pressed at a pressure of 50 kg / cm ² . After pressing and curing at a temperature of 60 ° C. for 10 hours, the mixture was cured by autoclave curing at 7 atm for 12 hours to obtain a sample of a wood fiber-containing cement board having a thickness of 15 mm and a specific gravity of 0.95. Then, the sample was visually observed and evaluated. FIG. 2 shows the evaluation results.
[0040]
The scatter deposition in the first forming chamber blows a wind having a wind speed of 20 m / sec in a direction opposite to the transport direction, while the scatter deposition in the fourth forming chamber has a wind speed of 20 m / sec in the same direction as the transport direction. The classification was carried out by blowing air / second.
The transport speed of the transport conveyor belt 50 was 15 m / min.
[0041]
(Example 2)
Except that a scraper was used instead of the roller of Example 1, a sample of a wood fiber-mixed cement board having a thickness of 15 mm and a specific gravity of 0.95 was obtained by treating under the same conditions as in Example 1. Then, the sample was visually observed and evaluated. FIG. 2 shows the evaluation results.
[0042]
(Comparative Example 1)
Except that the leveling process is not performed with a roller or a scraper in the fourth forming chamber 40, a cement plate mixed with wood fiber and having a thickness of 15 mm and a specific gravity of 0.95 is obtained by performing the processing under the same conditions as in the above-described Example 1 except for the above. Sample was obtained. Then, the sample was visually observed and evaluated. FIG. 2 shows the evaluation results.
[0043]
The method of evaluating the degree of fiber exposure and surface evaluation was determined by visually observing the sample surface, based on whether or not it could be put to practical use as a commercial product. If no fibers were exposed on the surface of the sample and it was beautiful, it was marked with “◎”. If the fiber was slightly exposed but it could be put to practical use, it was marked with “○”. When it was determined that a large number of fibers were exposed on the surface and the surface was uneven and it could not be used practically, it was evaluated as “Δ” or “X”. In addition, workability was determined as a criterion as to whether or not processing could be performed at a normal transport speed.
[0044]
As is clear from the results of fiber exposure and surface evaluation shown in FIG. 2, Examples 1 and 2 were superior to Comparative Example 1, and it was found that there was no problem in practical use as a commercial product. In particular, even in the case of Examples 1 and 2, it was found that a wood fiber-mixed cement board with a smooth surface and a beautiful surface could be obtained without lowering the productivity because the processing could be carried out at a normal conveying speed.
[0045]
【The invention's effect】
As is clear from the above description, according to the method for producing a wood fiber-mixed cement board according to claim 1 of the present invention, even if the raw material having a large particle size classified by the sieve is scattered and deposited so as to pierce, After leveling by the leveling means disposed immediately below the lower end, raw materials having a small particle size classified by a sieve are scattered and deposited on the surface. For this reason, a wood fiber mixed cement board with a smooth surface and a beautiful appearance can be obtained. As a result, even when the wood fiber-mixed cement board according to the present invention is coated, there is an effect that coating unevenness does not occur and a wood fiber-mixed cement board having excellent water resistance and frost damage resistance can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic front view showing a manufacturing apparatus according to an embodiment of the present invention.
FIG. 2 is a table showing observation results of Examples 1 and 2 and Comparative Example 1.
[Explanation of symbols]
10, 20, 30, 40 ... first, second, third, fourth forming chambers, 11, 21, 31, 41 ... mixture, 12, 22, 32, 42 ... supply conveyor belt, 13, 43 ... sieve, 14, 44: air duct, 15, 45: air outlet, 16, 46: air outlet, 50: conveyor belt, 51: lower mold plate, 53: sediment.

Claims (4)

A mixture containing cement and wood fibers as main raw materials is dropped in a forming chamber, classified by a sieve, and the raw material having a large particle size classified by the sieve is scattered and deposited from a lower end of the sieve on a lower die plate to be conveyed. The upper mold plate is placed on a sediment obtained by spraying and depositing the raw material having a small particle diameter classified by the sieve and leveled by a leveling means disposed immediately below the lower end of the sieve and then pressed and cured. A method for producing a wood fiber-mixed cement board, comprising curing. A mixture containing cement and wood fiber as main raw materials is dropped in a forming chamber and classified by a sieve, and the raw material having a large particle size classified by the sieve is scattered and deposited from a lower end of the sieve on a lower mold plate to be conveyed. In a manufacturing apparatus of a wood fiber-mixed cement board manufactured by spraying and depositing a raw material having a small particle size classified by the sieve, placing an upper mold plate on a sediment obtained by pressing and curing and curing.
An apparatus for producing a wood fiber-mixed cement board, characterized in that a leveling means for leveling a raw material having a large particle size classified by the sieve is disposed immediately downstream of a lower end of the sieve. The apparatus for producing a wood fiber-mixed cement board according to claim 2, wherein the leveling means is a roller. 3. The apparatus according to claim 2, wherein the leveling means is a scraper.

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