JPH0752130A - Production of fiber reinforced cement panel - Google Patents

Abstract

PURPOSE:To mold a uniform plate-shaped article by supplying a cement slurry in a uniform density state by utilizing the own. wt. of the slurry. CONSTITUTION:The supply direction of a cement slurry is upwardly inclined at an angle theta from the rear surface of a molding dehydration belt 3 to the upper surface of the belt 3 and the cement slurry is supplied from a dovetailed nozzle 1A flatly spreading toward the upper surface of the belt 3. Therefore, the cement slurry is diffused to the whole of the nozzle 1A in uniform density is the nozzle 1A spreading in the dovetailed state by the own wt. of the slurry to flow out of a nozzle emitting orifice 1B in this state. Further, the cement slurry is forcibly supplied from below successively to easily become a laminar flow state and can be emitted and supplied from the nozzle emitting orifice 1B in a uniform density state. By this constitution, a uniform plate-shaped article can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber-reinforced cement board, and more specifically, a cement slurry is supplied in layers on a molding dehydration belt, and moisture of the slurry is sucked and dehydrated on the belt to form a plate-like body. The present invention relates to an improved method for producing a fiber-reinforced cement board.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a fiber reinforced cement board, cement slurry B is fed in layers on a molded dehydration belt A from a flow box or an extrusion feeder C as shown in FIG. There is known a method for producing a fiber-reinforced cement board in which the water content of the cement slurry C is dehydrated by a suction dehydrator D while the plate-like body G is formed. The manufacturing method of these fiber-reinforced cement boards is called a papermaking method or a flow-on molding method among so-called wet manufacturing methods, and is well known as an industrial means for continuously mass-producing plate-shaped cement products.

[0003]

However, when a flow box is used for supplying the cement slurry C onto the molded dewatering belt A in the above-mentioned method for producing a fiber-reinforced cement plate, the flow of the cement slurry C is caused by natural flow. The solid content concentration of the cement slurry relative to the water content cannot be increased so much as to ensure the quality of the cement slurry.Therefore, the dehydration load becomes large, and the flow rate may differ between both ends and the center of the overflow weir of the flow box due to natural flow. Since it is difficult to provide a uniform supply amount, the arrangement of the reinforcing fibers contained in the cement slurry is also in an irregular state, and there is a problem that the reinforcing effect of the reinforcing fibers cannot be exerted effectively. .

When an extrusion supply device is used instead of this flow box, the cement slurry is forcibly extruded and supplied, and the solid content concentration relative to the water content of the cement slurry can be increased to some extent, so that the dehydration load is reduced. In addition to being able to reduce the scale of the molded dewatering belt, it is also possible to control the alignment of the reinforcing fibers to some extent by providing a weir at the discharge port of the extrusion supply device, which is a fiber with excellent strength. Although it has the advantage of being able to form a reinforced cement board, the structure of the extrusion feeder is considerably more complicated than that of a flow box, and because the cement hardens over time, maintenance and inspection are indispensable, increasing the cost of the entire facility and maintaining it. There was a drawback that management became troublesome.

[0005]

In view of the above problems, the present invention is a method for producing a fiber reinforced cement plate as described above, wherein the supply of cement slurry can be carried out uniformly without being significantly affected by the water concentration and is simple. The purpose of the present invention is to provide a method for producing a fiber-reinforced cement board that can be realized by an apparatus.

[0006]

That is, according to the method for producing a fiber-reinforced cement board of the present invention, cement slurry is supplied in layers on the molding dehydration belt 3, and moisture of the slurry is sucked and dehydrated on the belt. In the method for producing a fiber-reinforced cement board for molding a plate-like body G, the molded dehydration belt 3
When supplying the cement slurry to the upper side, the cement slurry is supplied from a dovetail-shaped nozzle 1A that is inclined upward from the lower surface of the belt toward the upper surface of the belt by θ and spreads flatter toward the upper surface of the belt. And also,

Another aspect of the present invention is a method for producing a fiber-reinforced cement board in which cement slurry is supplied in layers on a molding dehydration belt 3 and the board G is molded while sucking and dehydrating the water content of the slurry on the belt. When the cement slurry is supplied onto the molded dewatering belt 3, the cement slurry is supplied from the dovetail nozzle 1A that is inclined upward from the lower surface of the belt 3 toward the upper surface of the belt by θ and spreads flattened toward the upper surface of the belt. It is characterized in that the slurry is supplied and at the same time, the cement slurry is mixed with the brush roll 4 in the discharge direction at the discharge port 1B of the dovetail-shaped nozzle 1A.

[0008]

The method for producing a fiber-reinforced cement board according to the present invention is, as described above, a method of papermaking or a flow method in the so-called wet method in which cement slurry is supplied in layers on a forming dewatering belt and dehydrated to make a board. The on-molding method is assumed. As a means for supplying the cement slurry in this manufacturing method, the cement slurry is supplied from a dovetail-shaped nozzle 1A in which the direction of supplying the cement slurry is inclined upward from the lower surface of the belt to the upper surface of the belt and becomes flatter toward the upper surface of the belt.

Therefore, the cement slurry diffuses at a uniform density in the entire nozzle 1A by its own weight in the nozzle 1A spreading like a dovetail, and flows out from the nozzle discharge port in that state. Further, since the cement slurry is forcibly supplied from the lower side in sequence and supplied, the laminar flow state is likely to occur and the cement slurry can be discharged and supplied from the nozzle discharge port in a more uniform density state. When the solid content concentration of the cement slurry is low with respect to the water content, the cement slurry is supplied by gravity flow from the bottom of the cement slurry tank located at a position higher than the nozzle opening position, and when the solid content concentration is high, it is urged by a pump. It Further, if a brush roll 4 is provided at the discharge port 1B of the nozzle and the cement slurry is evenly mixed in the discharge direction, the fibers contained in the cement slurry can be provided with orientation, which also contributes to the improvement of the strength of the plate-shaped body.

[0010]

Embodiments of the present invention will be described below. 1 is a side view of an apparatus for carrying out the method of the present invention, and FIG. 2 is a plan view of FIG.

[Example 1] 45% by weight of cement, 45% by weight of silica sand powder, 5% by weight of pulp fiber as reinforcing fiber, and 5% by weight of lightweight aggregate were prepared as a raw material for cement slurry, and water was added to the cement mixture. Add slurry concentration
15%, 20% and 25% cement slurries were prepared.

Next, as a cement slurry supply device 1, as shown in FIG. 1, a cement slurry supply pipe 2 is a pipe having an inner diameter of 80 mm, a terminal width B is 450 mm, and a height h is 40 m.
The dovetail-shaped nozzle 1A having a length m in the flow direction of 450 mm and the discharge port 1B of the dovetail-shaped nozzle 1A is opened at the starting point 3A of the molding dewatering belt 3 from the feed pipe 2 portion by θ. The sheet-like body G having a thickness of 40 mm and a width of 450 mm was formed by discharging the cement slurry having various concentrations described above in a layered manner on the molding dehydration belt 3 so as to have an upward inclination angle of = 45 °.

[Embodiment 2] As a cement slurry supply device, a brush roll 4 having a bristle length of 40 mm and a diameter d of 80 mm is provided at the opening of the dovetail nozzle 1A used in Embodiment 1, as shown in FIG. A plate-like body G was molded in the same manner as in Example 1 except that the slurry was supplied by axially supporting the slurry and forcedly rotating the slurry at a speed slightly higher than the outflow speed of the cement slurry.

Comparative Example 1 A plate-like body G was molded in the same manner as in Example 1 except that the flow box shown in FIG. 4 was used as the cement slurry supply device 1. [Comparative Example 2] A plate-like body G was molded in the same manner as in Example 1 except that an extruder was used as the cement slurry supply device 1.

As for the molding state of the plate-shaped body, in Examples 1 and 2, it was possible to smoothly mold regardless of the concentration, but in the case of Comparative Example 1, uneven supply occurred when the cement slurry concentration was 20%.
In the case of 25%, it was almost impossible to supply a uniform thickness. Contrary to Comparative Example 1, Comparative Example 2 using the extrusion feeding device caused uneven feeding when the cement slurry concentration was 15%.

Next, the plate-like bodies G obtained in the examples and comparative examples were cut into 900 mm lengths to prepare test plates, which were cured by autoclave curing according to a conventional method and the bending strength was measured. became. In Table 1, * 1 indicates that the slurry concentration is too high to form a uniform plate, and * 2 indicates that the slurry concentration is too low to form a uniform plate, resulting in failure to measure strength. Show.

[0017]

As is apparent from Table 1, when the plate-like body is formed by the method of the present invention, it is possible to form a uniform plate-like body with almost no influence of the concentration of cement slurry. When supplying the slurry, the density of the slurry is uniformized by using the self-weight of the slurry and the slurry is supplied, so that it is possible to manufacture the fiber-reinforced cement board with a simple device without requiring a special device for that, for example, an extrusion supply device. It is also possible, and the strength of the obtained fiber reinforced cement plate is also excellent, and when a brush roll is provided at the discharge port, it is possible to impart orientation to the fibers contained, so that it is possible to form a plate-shaped body having particularly excellent bending strength. Have an effect.

[0018]

[Table 1]

[Brief description of drawings]

1 is a side view of an apparatus used in the method of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a side view of an apparatus used in another inventive method.

FIG. 4 is a side view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cement slurry supply device 1A ... Dovetail nozzle 1B ... Discharge port 2 ... Cement slurry supply pipe 3 ... Molding dehydration belt 3A ... Starting point of molding dehydration belt 4 ... Brush roll G ... Plate-shaped body

Claims (2)

[Claims] 1. A method for producing a fiber-reinforced cement board, which comprises forming cement slurry on a forming dehydration belt 3 in a layered manner and forming a plate-like body G while sucking and dehydrating water of the slurry on the belt. When the cement slurry is supplied onto the dewatering belt 3, the cement slurry is supplied from the dovetail-shaped nozzle 1A that is inclined upward from the lower surface of the belt 3 toward the upper surface of the belt 3 and spreads flatter toward the upper surface of the belt. A method for producing a fiber-reinforced cement board, comprising: 2. A method for producing a fiber-reinforced cement board, comprising forming cement slurry on a forming dehydration belt 3 in a layered manner and forming a plate-like body G while sucking and dehydrating water of the slurry on the belt. When supplying the cement slurry onto the dewatering belt 3, the dovetail-shaped nozzle 1 in which the direction of supplying the cement slurry is inclined θ from the lower surface of the belt to the upper surface of the belt and spreads flatter as it approaches the upper surface of the belt 1.
A method for producing a fiber-reinforced cement board, characterized in that the cement slurry is supplied from A and the cement slurry is evened in a discharge direction with a brush roll 4 at a discharge port 1B portion of the dovetail-shaped nozzle 1A.