JPS5835845B2 - Glass Cement Cement Banno Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a glass fiber reinforced cement board.

Cement is used in large quantities as a variety of building materials, but because it has poor tensile strength and impact resistance, it is often reinforced with fibers (asbestos fibers are commonly used as these fibers).

This asbestos-reinforced cement body is often used in the form of a board, which is known as an asbestos slate board.

However, asbestos fibers are commonly used as fibers in fiber-reinforced plastic bodies.

Its tensile strength is extremely low compared to glass fiber.

For this reason, it was proposed to reinforce cement with glass fibers, and these ideas were disclosed in the British magazine "Glass Technology" published in June 1968, Japanese Patent Publications No. 43-2118 and Japanese Patent Publication No. 16691-1973, etc. ing.

When reinforcing a cement body by mixing glass fibers, the reinforcement mechanism cannot be discussed in general terms, but generally speaking, when a tensile force is applied to a cement body mixed with glass fibers, it acts on the glass fibers. It is possible to consider a mechanism in which the tensile force exerted by the glass fibers balances out the shear force acting on the interface between the glass fibers and the cement, and most of the tensile force is borne by the glass fibers.

Of course, this assumes that the glass fibers are uniformly mixed into the cement.

The manufacturing method of glass fiber reinforced cement board described in Japanese Patent Publication No. 48-16691, which is one of the conventional examples, involves distributing cement and glass fibers alternately on a belt conveyor, and then distributing the cement and glass fibers. This is a method in which water is sprinkled into the laminate, the laminate is compressed with a compression roller, and then cured and hardened.
The resulting board material is one in which glass fiber layers and cement layers are alternately laminated.

Therefore, due to the difference in thermal expansion coefficient and Young's modulus between the glass fiber layer and the cement layer, shear stress is generated between the layers, forcing delamination, and no effective reinforcing effect can be expected.

According to the method of mixing cement and glass fibers in advance and spreading this mixture on a belt conveyor, there is no problem of delamination as described above, but the amount of glass fiber increases as it reaches the surface of the spread layer, and the amount of glass fiber increases. There is a problem that uneven distribution is unavoidable.

This is because the falling speed of the glass fibers when the mixture is dropped onto the belt conveyor is slower than the falling speed of the cement particles, and this difference in falling speed is due to the shape of the glass fibers. The main reason is that the air resistance that acts is a dog.

The method for manufacturing a glass fiber reinforced cement board according to the present invention includes:
This is a method that can reduce the uneven distribution of glass fibers, in which a mixture of glass fibers and cement is dropped onto a belt conveyor to form a layer, and the surface of the layer is coated with water after permeating into the layer. When pressurizing and then curing and curing, scrape off a predetermined amount of the glass fibers that are unevenly distributed in large quantities near the surface of the layer, make the glass fiber density in the layer thickness direction constant g, and make the scraped glass. The fibers are returned onto the belt conveyor to the point where the mixture falls.

The present invention will be explained below with reference to the drawings.

In the figure, 1 is a belt conveyor.

A feeder 2 is divided into two left and right chambers 2a and 2b by a central partition 21, and a common outlet 3 is provided at the lower end of each chamber.

These chambers 2a. Among the chambers 2b, one chamber 2a is used for supplying cement, and the other chamber 2b is used for supplying glass fiber.

4a is a roller gate provided at the bottom of the cement supply chamber 2a, and 4b is a roller gate provided at the bottom of the glass fiber supply chamber 2b.

5 is a spike roll provided directly below the common outlet 3.

6 is a picker roll (a roll on which many thin wires are implanted); 7 is a casing in which a slit 71 is provided.

8 is a cover.

The cement supply chamber 2a is filled with a mixture of cement, silica, asbestos, etc., and the glass fiber supply chamber 2b is filled with chopped glass strands.

By the rotation of the roller gates 4a and 4b in each chamber 2a and 2b, a predetermined amount of the cement mixture and glass chopped strands are respectively dropped onto the spike roll 5, and these are mixed by 50 revolutions of the spike roll.
This is scattered on the belt conveyor 1.

This scattering layer A contains a larger amount of glass fibers toward the upper layer.

As the belt conveyor 1 moves, the above-mentioned scattered layer A is sent to the picker roll 6, an appropriate amount of glass fibers near the upper layer are picked up by the picker roll 6, and this pitched up glass fiber is passed through the slit 7 of the casing 7.
1, it is returned onto the belt conveyor 1 directly below the spike roll 5.

This glass fiber is added to the glass fiber cement mixture from spike roll 5.

9 is a water dripping container, and the mixture layer B from the picker roll 6 is wetted by the dripping water from the container 9.

11 is a pressure roller; 12 is a cutter; the surface of the wet mixture layer C is pressed by the pressure roller 11, and then cut by the cutter 12;

The original plate thus obtained is heated in an autoclave according to a conventional method, and cured by this heating to form a final product.

In the method for manufacturing a glass fiber reinforced cement board according to the present invention, as described above, a mixture of glass fibers and cement is sprinkled onto the belt, and a predetermined amount of glass fibers near the surface of the sprayed layer are scraped off. Therefore, the amount of glass fibers near the surface of the scattering layer, that is, the portion containing more glass fibers than the lower layer, can be made sufficiently equal to the amount of glass fibers in the lower layer of the scattering layer.

In the present invention, it is difficult to make the density of glass fibers in the layer thickness direction strictly constant, but according to the present invention, the mixture of glass fibers and cement is only spread on a belt conveyor. It is clear that the uneven distribution of glass fibers mentioned above can be reduced compared to the conventional example.

Therefore, compared to the conventional example, it is possible to reduce the reduction in reinforcing effect due to uneven distribution of glass fibers.

[Brief explanation of drawings]

The drawing is a schematic diagram of the manufacturing apparatus used in the present invention. In the figure, 1 is a belt conveyor, 6 is a picker roll, 9 is a water dripping container, 11 is a pressure roll, 12 is a cutter, and A, B, and C are glass fiber and cement mixture layers.

Claims (1)

[Claims] 1. When a mixture of glass fibers and cement is dropped onto a belt conveyor to form a layer, the surface of the layer is pressurized after water has penetrated into the layer, and then cured and hardened, the above-mentioned method is applied. A predetermined amount of the glass fibers unevenly distributed near the surface of the layer is removed by a picker roll to make the glass fiber density almost constant in the layer thickness direction, and the removed glass fibers fall onto the belt conveyor. A method for manufacturing a glass fiber reinforced cement board, characterized in that it is returned to a location.