JP2636973B2 - Extrusion molding method for plate-like cement products - 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 extruding a plate cement product, and more particularly to a method for extruding a plate cement product which does not require an extrusion aid.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a cement product, a cement slurry is supplied to an extruder, a product having a predetermined cross-sectional shape is extruded from a die, and the product is cut into an appropriate length to form a product and cure and harden. Molding methods are well known. This extrusion molding method has an advantage that it is very advantageous for mass production because it can continuously mold a molded article having a complicated cross-sectional shape.

[0003]

[Problems of the prior art] However, when extruding a cement product, the concentration of the extruded cement slurry is usually 60% or more (solid content 60% or more, moisture content) to maintain the shape retention of the product immediately after extrusion. (40% or less). Therefore, there is a problem that the dispersibility of the reinforcing fibers is poor due to poor fluidity at the time of mixing the raw materials, and a material having sufficient strength cannot be obtained. . In particular, the above-mentioned drawbacks are remarkable in extrusion molding of a plate-like product having a width several times or more as compared with the product thickness.

Further, the extruder requires a large horsepower due to flow resistance, and it is necessary to add an extrusion aid such as methylcellulose to reduce the extrusion resistance, resulting in an increase in material costs. was there.

Although it is conceivable to reduce the slurry concentration to a concentration lower than 60% in order to solve such a problem, the extrusion resistance is considerably reduced as the slurry concentration decreases, but the shape retention is very poor. And a slurry concentration of 25
When the content is up to 35%, in the case of the above-mentioned plate-shaped product, there is a drawback that a dehydration phenomenon occurs at the mouth portion of the extruder and extrusion may not be possible.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has reduced extrusion resistance, does not require an extrusion aid such as methylcellulose, and has a slurry concentration of 25 to 25.
It is an object of the present invention to provide a method for extruding a plate-like cement product which does not cause dehydration at a base even at a low concentration of 35%.

[0007]

The method for extruding a plate-like cement product of the present invention comprises the steps of:
Water is added to an inorganic composition consisting of 40 to 50% by weight of silica sand, 5 to 10% by weight of reinforcing fibers such as pulp fiber, and 5 to 10% by weight of other necessary lightweight aggregate to make a slurry concentration of 25 to 35%. The product is extruded by an extruder to a thickness of at least three times the thickness of the target product, and immediately after the molding, the molded body is suction-dehydrated by roll pressure and suction, and then cured to a predetermined thickness and cured. It is assumed that.

[0008]

[Function] In the extrusion of cement products, the slurry must have a slurry concentration of 60% or more (solid content of 60% or more and moisture of 40% or less) as described above, in order to impart the shape retention of the product immediately after extrusion. Must. On the other hand, if the slurry concentration is 60% or less, especially the slurry concentration is 50% or less, the fluidity of the slurry is considerably improved, but if the slurry has a low concentration of about 25 to 35%, the width of the plate is several times larger than the thickness. When the product is extruded, dehydration occurs at the mouthpiece and extrusion becomes impossible.

Therefore, the present inventors have conducted various studies on the correlation between the density and the shape of the die, and found that the height of the die (that is, equivalent to the thickness of the plate-like molded product) is three times or more the target product shape. In addition, it was confirmed that a precise molded product could be molded even with a slurry having a very low concentration of 25% to 35% by combining the process of compressing and extruding an extruded product by roll pressure and suction to cut off water. It was done.

That is, in the present invention, when the slurry concentration is higher than 35%, the extrusion resistance increases and the addition of an extrusion aid such as methylcellulose is required, but the uniform mixing is not sufficiently achieved. When the concentration is lower than 10%, it is advantageous in terms of extrusion resistance and uniform mixing, but it has been found that the shape of the molded product cannot be completely maintained even when the roll pressing and suction steps are combined.

[0011]

Next, an embodiment of the present invention will be described. Mix 40% by weight of cement, 40% by weight of silica sand, 10% by weight of pulp fiber and 10% by weight of pearlite, dry-mix them uniformly, and add water to make a slurry with a concentration of 25%, 30% and 35%. None, as shown in FIGS. 1 and 2, a extrusion plate 1 is used to extrude a molding plate 2 having a height 1h of a die 3A and a width B 25cm with respect to a product thickness 1cm.
At the same time, the sample was compressed at a linear pressure of / cm, suction-dehydrated from the back surface at 400 mmHg from the suction box 4, and dehydrated and shrunk to a thickness of about 1 cm. Next, the formed plate 2 was taken out by a take-up conveyor 5, and the extruded plate 2 was cut at intervals of 45 cm, and subjected to steam curing in an autoclave.

When the above-mentioned test plate 2 was subjected to a JIS No. 4 bending test, the results shown in Table 1 were obtained. In Table 1, Comparative Example 1 had a slurry concentration of 60% and was extruded by adding 1% by weight of methylcellulose to the composition of the above Example, and Comparative Examples 2 and 3 had a die height in the Example production method. The values for 1.5 cm and 2.5 cm are shown.

[0013]

As is apparent from Table 1, in the embodiment of the present invention, extrusion molding is possible even when the slurry concentration is 25% or 35%, and the bending strength is 98 kg / cm ² and 93 k.
It was confirmed that g / cm ² , a strength not obtainable even in Comparative Example 1, was obtained.

[0015]

As described above, according to the method of the present invention, extrusion molding can be performed without causing dehydration at the die even when the slurry concentration is extremely low, and an extrusion aid such as methyl cellulose can be used. This makes it possible to mold a large number of high-precision molded products without requiring them.

[Brief description of the drawings]

FIG. 1 is a side view of an apparatus for performing the method of the present invention.

FIG. 2 is a front view of a mouth portion of an extrusion molding apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 1A Cap 2 Molding plate 3 Rubber roll 4 Suction box 5 Pick-up conveyor

Claims (1)

(57) [Claims] 1. Water is added to an inorganic composition comprising 40 to 50% by weight of cement, 40 to 50% by weight of silica sand, 5 to 10% by weight of reinforcing fibers such as pulp fiber, and 5 to 10% by weight of other necessary aggregate lightweight aggregate. In addition, the slurry concentration is 25 to 35%, and the slurry is extruded from an extruder to a thickness three times or more the shape of the target product, and immediately after the molding, the molded body is subjected to suction dehydration by roll pressure and suction. A method for extruding a plate-shaped cement product, comprising curing to a predetermined thickness and then curing.