JPH04292907A - Extrusion molding method of cement product - Google Patents

Abstract

PURPOSE:To enable high-precision molding without necessitating an extrusion auxiliary material, by a method wherein slurry obtained by compounding cement, quarts sand, a reinforcement fiber and aggregate with each other respectively at the specific rates is extrusion-molded, the molded body is sucked and dehydrated directly after the molding, cured and hardened. CONSTITUTION:Slurry having density of 30-50% is obtained by adding water to a mineral compound comprised of 40-50wt.% cement, 40-50wt.% quartz sand, a 5-10wt.% reinforcing fiber such as a pulp fiber and the 50-10wt.% other necessary aggregate or light-weight aggregate (such as perlite). Then the slurry is extrusion-molded by an extruder 1 and simultaneously with compression of the surface of the slurry with linear pressure of about 1kg/cm by a rubber roll 3 directly after molding, suction and dehydration are made to perform through the rear at about 400mm Hg and a molded board 2 having a fixed thickness is obtained. Then the molded board 2 is received by a receiving conveyor 5, cut into fixed lengths, then steam curing and hardening of the same are made to perform by an autoclave and a product is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for extrusion molding cement products, and more particularly to a method for extrusion molding cement products that does not require an extrusion aid.

0002

[Prior Art] A conventional method for manufacturing cement products is extrusion, in which cement slurry is supplied to an extruder, a product with a predetermined cross-sectional shape is extruded from a die, and the product is cut into appropriate lengths and cured to harden. Molding methods are well known. This extrusion molding method has the advantage that even products with complicated cross-sectional shapes can be continuously molded, making it extremely advantageous for mass production.

0003

[Problems with the prior art] However, when extruding cement products, the concentration of the extruded cement slurry is usually 60% or more (solid content 60% or more, water content Therefore, there was a problem that the dispersibility of reinforcing fibers was poor due to poor fluidity during mixing of the raw materials, making it impossible to obtain a slurry with sufficient strength.

[0004] Furthermore, due to the flow resistance, the extruder requires a large horsepower, and it is necessary to add an extrusion aid such as methyl cellulose to reduce the extrusion resistance, which increases the cost of materials. was there.

[0005]

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the present invention has been made for the purpose of providing an extrusion molding method for cement products that reduces extrusion resistance and does not require extrusion aids such as methyl cellulose. It is.

[0006]

[Means for Solving the Problems] That is, the extrusion molding method for cement products of the present invention includes 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 fibers, and other necessary bones. Water is added to an inorganic mixture consisting of 5 to 10% by weight of lightweight aggregate to make a slurry concentration of 30 to 50%, and the slurry is extruded from an extruder. Immediately after the molding, a molded product is formed by roll pressure and suction. It is characterized by dehydrating it and then curing it.

[0007]

[Function] In extrusion molding of cement products, in order to give the product shape retention immediately after extrusion, as mentioned above, the slurry concentration should be 60% or more (solid content 60% or more, moisture 40% or less).
The concentration shall be as follows. On the other hand, if the slurry concentration is 60% or less, especially 50% or less, the fluidity of the slurry is considerably improved, and the improvement effect is remarkable in terms of uniform mixing and extrusion resistance. Therefore, the present inventors investigated various minimum slurry concentrations within a range that can maintain shape retention immediately after molding, and found that if the process of removing excess moisture by roll pressure and suction is combined, the slurry can be It was confirmed that extremely accurate molded products could be molded within the range of 50% to 30% concentration.

That is, in the present invention, the slurry concentration is 50%.
When the slurry concentration is lower than 30%, the extrusion resistance increases and the addition of extrusion aids such as methylcellulose becomes essential, while uniform mixing is not achieved sufficiently.When the slurry concentration is lower than 30%, the extrusion resistance and uniform mixing become more difficult. Although this method is advantageous in terms of aspects, it has been found that even if roll pressure and suction steps are combined, the shape of the molded product cannot be maintained completely.

[0009]

[Example] Next, an example of the present invention will be described. Cement 40% by weight, silica sand 40% by weight, pulp fiber 10% by weight
, 10% by weight of perlite, and after uniformly dry mixing these, water was added to make slurries with concentrations of 50% and 30%, and as shown in Fig.
Immediately after extrusion molding, the molded plate 2 with a width of 25 cm was compressed with a rubber roll 3 at a linear pressure of 1 kg/cm, and at the same time, the back surface was dehydrated by suction from a suction box 4 at 400 mmHg.

Next, this molded plate 2 is taken up and conveyed to a conveyor 5.
The extrusion-molded plate 2 was taken up and cut into 45 cm pieces, and steam-cured in an autoclave. The above test plate 2 was subjected to a JIS No. 4 bending test to determine the presence or absence of cracks, and the results shown in Table 1 were obtained.

In Table 1, Comparative Example 1 is obtained by adding 1% by weight of methylcellulose to the above-mentioned Example formulation with a slurry concentration of 60% and extrusion molding, Comparative Examples 2 and 3.
indicates the case where roll pressure and suction were not performed in the production method of the example.

As is clear from Table 1, in the example of the present invention, even though the slurry concentration was 30%, the bending strength was 100 kg/cm2, which is a strength not seen in other examples or comparative examples. It was also confirmed that even when the slurry concentration was 50%, it exhibited superior strength compared to other comparative examples.

[0013]

[0014]

[Effects of the Invention] As explained above, according to the method of the present invention, extrusion performance is improved by lowering the slurry concentration, and a large number of molded products with high precision can be produced without the need for extrusion aids such as methyl cellulose. This makes it possible to mold the material into

[Brief explanation of the drawing]

1 is a side view of an apparatus implementing the method of the invention; FIG.

[Explanation of symbols]

1 Extruder 2 Molded plate 3 Rubber roll 4 Suction box 5 Take-up conveyor

Claims (1)

[Claims] [Claim 1] 40 to 50% by weight of cement, 40% of silica sand
~50% by weight, 5-10% by weight of reinforcing fibers such as pulp fibers,
Other Necessary Aggregates Water is added to an inorganic mixture consisting of 5 to 10% by weight of lightweight aggregate to make a slurry concentration of 30 to 50%, and the slurry is extruded using an extruder.
A method for extrusion molding of cement products, characterized by dehydrating the molded product by pressure and suction, and then curing it.