JPS62275034A - Production of foamed plate and kiln used therefor - Google Patents

Abstract

PURPOSE:To produce a foamed plate excellent in performance in high productivity by pressing the foamed plate after calcination while quenching it by direct contact of a pressurization cooling means and thereafter reraising the surface temp. of the foamed plate. CONSTITUTION:A foamable mineral raw material obtained by pelletizing the mixture of artificial glass and porous volcanic rock or the like is fed on a belt conveyor 3 from a feed hopper 4 and evened by a preliminary roller 5 to regulation it to nearly uniform thickness and sent into a kiln 1. After raising it in temp. at a temp. raising zone of the kiln 1, it is heated in a calcination zone and foamed. The foamed plate 2 is directly brought into contact with pressurization cooling rolls 6 and quickly cooled in such a range that the central part of the foamed plate 2 is not reached to softening point or below. The surface of the foamed plate 2 after quenching is reraised in temp. by atmospheric temp. Thereby the ununiformity of temp. distribution of the foamed plate 2 is eliminated and the generation of thermal stress due to quenching is relaxed. Further since both the upper and the lower side are directly pressurized by the rolls 6, uniform and sure pressurization is performed and the foamed plate excellent in performance can be produced.

Description

[Detailed description of the invention] 3. Detailed description of the invention.

[Industrial Field of Application] The present invention relates to a method for manufacturing a foam board and a firing furnace used therein.

More specifically, the foamed board after firing is rapidly cooled and pressed by direct contact with a pressurized cooling means, and then the surface temperature of the foamed board is raised again to relieve the strain stress within the foamed board, resulting in excellent performance. The present invention relates to a method for manufacturing a foamed board that can increase the production rate, that is, productivity, by making the foamed board transparent and quenching it, and a firing furnace used therein.

[Prior Art] Foam boards have traditionally been widely used in prefabricated houses because they are lightweight, easy to handle, and have excellent heat retention, fire resistance, and durability.

Such foam boards are generally made of natural glass, human glass, porous volcanic rock, igneous rock, sedimentary rock, tuff, etc. as the main raw materials.
It can be obtained by heating and foaming these, and then pressurizing and fusing the resulting foam board with a pressure roll or the like, and molding at the same time.

The above steps are usually carried out continuously in a furnace, and the expandable material supplied onto the belt running in the furnace undergoes the steps of heating, firing, and cooling, and then forms a foam plate in the desired shape. It is carried out from the furnace as

By the way, when the surface of the foam board is rapidly cooled in the cooling process, the temperature near the surface drops rapidly, and the temperature distribution near the surface and inside becomes uneven, resulting in tensile stress near the surface and compressive stress inside. A problem arises in that stress is generated and the foam board is damaged due to these stresses.

In particular, thermal strain stress is likely to occur between the annealing point and the strain point, and there is a problem in that the temperature non-uniformity in the thickness direction of the foam board becomes several degrees Celsius or more, causing the foam to break due to the thermal stress.

In order to prevent damage to the foam board due to such thermal stress, a conventional method of cooling has been to blow air onto the top and bottom surfaces of the foam board.In this case, the temperature distribution of the foam board is uniform. In order to maintain its properties, the cooling time is set long and the foam board is gradually cooled down.

Further, as shown in Japanese Utility Model Publication No. 53-50759, the foam board was pressurized by applying pressure to the lower surface of the foam board via a belt conveyor.

[Problems to be solved by the invention However, the above-mentioned cooling method using air blowing
There has been a problem in that the cooling rate cannot be set quickly, and therefore cooling takes time, which is a major hindrance when trying to improve the production efficiency of foam boards.

This problem has become more pronounced as the thickness of the foam board increases, since the cooling time takes up a larger portion of the total process time.

Furthermore, in the conventional method, pressure was applied to the bottom surface of the foam board via a belt conveyor, which resulted in problems in that the dimensional accuracy in the thickness direction decreased and the smoothness of the bottom surface of the foam board could not be changed. Ta.

In view of the above-mentioned problem, the present invention aims to provide a method for manufacturing a foam board and a firing furnace used therein, which eliminates the drawbacks of the conventional example. In other words, by directly rapidly cooling the foam using a pressurized cooling means such as a roll, it is possible to shorten the cooling time, thereby increasing production efficiency and reducing product costs. The purpose of the present invention is to provide a method for manufacturing a foam board that has high dimensional accuracy in the thickness direction and excellent smoothness on both the upper and lower surfaces by directly pressurizing the foam board without using any media, and to provide a firing furnace used therein. . In that case, the occurrence of thermal stress due to rapid cooling can be alleviated by passing the foam board through a strain temperature atmosphere after quenching and raising the surface temperature again to eliminate uneven temperature distribution on the foam board, causing damage to the foam board. There is no such thing as doing so.

[Means for Solving the Problems] The manufacturing method of the present invention is such that when manufacturing a foam board by heating and pressing a foamable inorganic raw material in a firing furnace, the manufacturing method is provided in a cooling zone in the firing furnace and the The method is characterized in that the fired foam board is rapidly cooled by a pressurized cooling means that is in direct contact with the upper and lower surfaces of the foam board, and then the surface temperature of the foam board is raised again in an atmosphere within the above temperature range.

Further, the firing furnace of the present invention used in the above method is a continuous firing furnace in which a foamed inorganic raw material is heated and suppressed on a belt conveyor running inside the furnace to form a foam board, and a cooling zone in the firing furnace is provided. At least a pair of rolls are provided that rotate in contact with the upper and lower surfaces of the foam board, and the belt conveyor separates from the foam board just before the first roll and runs outside the rolls, and the roll is passed inside thereof. It is characterized in that the foam board is cooled by a fluid.

[Function] In the method for manufacturing a foamed board of the present invention, the foamed board is rapidly cooled by rolls that rotate in direct contact with the upper and lower surfaces of the foamed board, and after being rapidly cooled, the foamed board is passed through a strain temperature atmosphere. Since the surface temperature rises again and the non-uniformity of the temperature distribution of the foam board is eliminated, the generation of thermal stress due to rapid cooling is alleviated.

Furthermore, since both the upper and lower surfaces are directly pressed by rolls, uniform and reliable pressure can be achieved.

[Example] Next, the manufacturing method of the present invention and the firing furnace used therein will be explained based on the drawings.

FIG. 1 is a schematic explanatory diagram showing an embodiment of the firing furnace of the present invention. In the figure, (1) is a firing furnace.
) is a belt conveyor (3) that transports the foam board (2).
is installed. The belt conveyor (3) is preferably mesh-shaped in order to uniformly diffuse the volatile components during foaming from the upper and lower surfaces and to perform uniform heat transfer on both the upper and lower surfaces. A ceramic belt or the like is used.

The foamable inorganic raw material to be fired is a pellet made from a mixture of natural glass, human glass, porous volcanic rock, igneous rock, tuff, etc., and the pellet is conveyed from the supply hopper (4) to the belt conveyor ( 3) Appropriate total supply on top. The supplied pellets are smoothed by a preliminary roller (5) to have a substantially uniform thickness, and then sent into the firing furnace (1). Thereafter, the pellet is heated to 1H in a temperature raising zone, and then heated and foamed in a firing zone.

Although the temperature increase varies depending on the particle size and composition of the raw materials, it is sufficient to increase the temperature at a rate of 80° C. per minute, for example, and is not particularly limited in the present invention. The firing temperature also varies depending on the particle size of the raw material, the foaming rate, the uniformity of the pore size of the raw material, etc., as well as the temperature increase, but it is generally 700 to 1100°C.

Furthermore, the firing time may be appropriately selected depending on the melting temperature of the raw material, the foaming rate of the raw material, the uniformity of the pore diameter of the raw material, and the like.

The manufacturing method of the present invention is characterized by the cooling step that follows the above firing step. That is, the foam board (2) foamed by firing is cooled by a pressure cooling roll (6) which is a pressure cooling means.
The foam board (2) is pressurized and fusion-molded and cooled at the same time.At this time, the cooling is done by direct contact between the roll (6) and the foam board (2), so that the center or middle layer of the foam board (2) softens. It is carried out rapidly within a range that does not drop below the point. In that case, the thermal strain stress generated on the surface of the foam board (2) by rapid cooling is relieved by passing the foam board (2) through a strain temperature atmosphere after cooling and raising the surface temperature again. (2) will not be damaged.

In the conventional cooling method using air blowing, the air blown onto the foam board (2) cools the foam board (2) and diffuses into the furnace, so that the atmosphere inside the furnace on the exit side from the cooling position is lower the temperature. Therefore, once cooled, the foam board is gradually cooled at the furnace atmosphere temperature and transported out of the furnace without the temperature rising again. However, since the cooling in the present invention is contact cooling using the pressurized cooling roll (6), there is no flow of cold air into the furnace. Therefore, the surface of the foam board (2) after quenching can be raised again by the ambient temperature, and the thermal strain stress caused by the quenching can be alleviated. That is, after quenching with the pressurized cooling roll (6), the center or middle layer of the foam board (2) is at the softening point or annealing point, while the surface is solidified by contact quenching and tensile stress is generated. By heating again, the stress is alleviated, and the heat in the center or middle layer is transferred to the surface, which speeds up the uniformization of the temperature of the foam, thereby alleviating the thermal strain stress.

A fluid such as water or air can be used as a cooling source for the pressurized cooling roll (6). The surface temperature of the roll (6) may be determined in consideration of the lK degree, viscosity, production speed, etc. of the foam board (2), and can be set arbitrarily. Temperature control may be performed, for example, by controlling the flow rate of cooling water or cooling air, whereby the surface temperature of the pressurized cooling roll (6) can be kept constant.

In the present invention, it is of course possible to adjust the surface temperature of the roll (6) using control methods other than those described above.

Further, in the above-mentioned pressure cooling process, the foam board (2) is separated from the belt conveyor (3) immediately before the pressure cooling roll (6), and both the upper and lower surfaces are directly affected by the roll (6), that is, the foam board (2) is ), both sides of the foam board (2) can be made smooth.

As shown in Figure 1, the foam board (2) is placed on a pressure cooling roll (
After being pressurized and cooled by step 6), it is moved on conveyor rolls (7) toward the exit of the furnace.

During this movement, as described above, the surface temperature of the foam board (2) is raised again by the atmospheric temperature in the furnace, and the thermal strain stress caused by the rapid cooling is alleviated.

The ambient temperature in the firing furnace is preferably within the range of 350 to 900°C from the viewpoint of slow cooling and reheating of the foam board (2). The optimal value within this range is foam board (2)
Although it is determined depending on various conditions such as the type of raw material and the moving speed of the belt conveyor (3), it is necessary to set the temperature to be higher than the transition temperature of the foam (2) in order to achieve the purpose of the present invention. . The optimum value for the surface temperature of the roll is also determined by the foam board (2).
It is determined depending on the type of raw material, the moving speed of the belt conveyor (3), etc.

In the present invention, cooling is performed by rolls within a range in which the center or middle layer of the foam board (2) does not fall below the softening point, but at this time, as mentioned above, the surface temperature drops faster than the inside, so tensile stress occurs, and compressive stress is generated inside.

After rapid cooling, if the foam board (2) is at a high temperature above its softening point, the thermal stress will be relaxed in a short time and it will be in a stress-free state despite the existence of a temperature difference between the surface and the inside, but slow cooling This is not preferable because it takes time. In the present invention, cooling can be performed safely and in a short time by heating the foam board (2) again in a transition temperature atmosphere.

Next, the manufacturing method of the present invention and the firing furnace used therein will be explained based on Examples, but the present invention is not limited to these Examples.

Example 1 Nagano white clay 82.5% (weight%, same below), soda ash 1
Raw material consisting of 2% dolomite, 5% dolomite, and 0.5% SIC (
A blended granulated product (softening point: 680°C, transition point: 630°C) was fed from a supply hopper onto a belt conveyor, and fired under the following conditions. For cooling after firing, a contact quenching method using pressure cooling rolls was adopted.

Firing temperature: 1020°C Temperature inside the foam after quenching: Near 30-680°C Atmospheric temperature inside the furnace after cooling and pressurization: 2650-630°C Conveyor movement speed: 213cm The foam board divided into 1 sections has clutter on the surface. There was no occurrence of blemishes, and both the front and back surfaces had a homogeneous and smooth finish.

The relationship between the manufacturing time and the surface temperature of the foam in Example 1 is shown in the second example.
As shown in the figure.

In Figure 2, 〈field〉 is the starting point of firing, 〈mountain〉 is the cooling start point, (C) is the cooling end point, and (small is the exit point of the furnace.As is clear from Figure 2, the foam plate The surface temperature of is rapidly decreased by contact cooling by the rolls, but after being cooled by the rolls, the temperature rises again.After that, the temperature gradually decreases again until it reaches a predetermined temperature (120
It took 90 minutes to reach 'C).

Example 2 Nagano white clay 64.5%, glass powder 30%, dolomite 5%
, SiCQ, 5% (softening point: 20° C., transition point: 2,630° C.) was mixed and granulated and fed from a supply hopper onto a belt conveyor, and fired under the following conditions. For cooling after firing, rapid contact cooling using pressure cooling rolls was used.

Firing temperature: 1050°C Temperature inside the foam after quenching Near 70-720°C Atmospheric temperature inside the furnace after cooling and pressurization: 680-630°C Conveyor movement speed: 28cm/The divided foam board is placed on the surface There is no occurrence of cracks, tsuku, etc.
Both the front and back surfaces had a homogeneous and smooth finish.

Example 3 Raw material consisting of 50% glass powder, 20% silica powder, 14.5% borax, 10% Nagano white clay, 5% sodium silicofluoride, and 5% SiCO (softening point: 580°C, transition point 480°C) ) was blended and granulated and fed onto a belt conveyor from a supply hosonoku, and fired under the following conditions. For cooling after firing, a contact quenching method using pressure cooling rolls was adopted.

Firing temperature: Near 30℃ Temperature inside the foam after quenching: 2630~580℃ Atmosphere temperature inside the furnace after cooling and pressurization: 550~480℃ Conveyor moving speed: 28cm/Separated foam board has cracks on the surface There were no occurrences of such problems, and both the front and back surfaces had a homogeneous and smooth finish.

Comparative Example 1 A foam board was produced in the same manner as in Example 1, except that the air blowing method was used for cooling after firing.

A large number of cracks as shown in FIG. 3 were observed on the surface of the foam board obtained.

Comparative Example 2 A foam board was produced in the same manner as in Example 2, except that the air blowing method was used for cooling after firing.

A rack was observed on the surface of the obtained foam board as shown in FIG.

Comparative Example 3 A foam board was produced in the same manner as in Example 3, except that the air blowing method was used for cooling after firing.

A rack was observed on the surface of the obtained foam as shown in FIG.

Comparative Example 4 A foam board was produced in the same manner as in Example 1, except that the air blowing method was used for cooling after firing, and the conveyor moving speed was 19 cm/min.

The obtained foam board had no cracks on the surface and had a uniform finish on both the front and back surfaces.

The relationship between the manufacturing time and the surface temperature of the foam in Comparative Example 4 was
As shown in the figure. As is clear from FIG. 2, the surface temperature of the foam board rapidly decreases due to cooling by air blowing, and after the blowing, the temperature gradually decreases due to natural cooling. It took 130 minutes to reach the specified temperature (120°C).

Comparative Example 5 A foam board was produced in the same manner as in Example 2, except that the air blowing method was used for cooling after firing, and the conveyor moving speed was set to 17 co+/min.

The obtained foam board had no cracks on the surface and had a uniform finish on both the front and back surfaces.

Comparative Example 6 A foam board was produced in the same manner as in Example 3, except that the air blowing method was used for cooling after firing, the lower surface of the foam board was pressurized via a belt conveyor, and the conveyor moving speed was 21 cm/min. was manufactured.

The obtained foam board had no cracks on the surface, but the smoothness of the lower surface was inferior to that of Example 3.

From Figure 2, when using the manufacturing method of the present invention, it is possible to lower the surface temperature of the foam to a predetermined temperature in a shorter time than with the conventional manufacturing method that uses a cooling method using air blowing. Recognize.

[Effects of the Invention] As detailed above, according to the manufacturing method and firing furnace of the present invention, the cooling rate can be increased without causing damage to the foam board due to thermal strain stress. In other words, it is possible to shorten the manufacturing time from heating to cooling, thereby increasing production efficiency, thereby reducing the cost of the product.

In addition, since pressure cooling is carried out directly from both sides of the foam board using rolls, the dimensional accuracy in the thickness direction is excellent, and both sides of the foam board are homogeneous, smooth, and have an excellent finish.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an embodiment of the firing furnace of the present invention;
Figure 2 shows the relationship between the manufacturing time and surface temperature of the foam board in Example 1 of the present invention and Comparative Example 4;
FIG. 5 is a diagram showing the surface condition of the foam boards manufactured in Comparative Examples 1 to 3, respectively. (Main symbols on the drawings) (1): Firing furnace (2): Foam board (3): Belt conveyor (6): Pressure cooling roll Patent applicant National Housing Industry Co., Ltd. Haka 1 representative patent attorney Asahina Sota and 1 other person6
.

Claims (1)

[Scope of Claims] 1. When manufacturing a foamed board by heating and pressing a foamable inorganic raw material in a firing furnace, a foam plate provided in a cooling zone in the firing furnace and in direct contact with the upper and lower surfaces of the foamed board. A method for producing a foamed board, which comprises rapidly cooling the fired foamed board using a pressurized cooling means, and then raising the surface temperature of the foamed board again in an atmosphere within the temperature range. 2. The manufacturing method according to claim 1, wherein the ambient temperature of the cooling zone is 350 to 900°C. 3. In a continuous firing furnace in which a foam board is formed by heating and pressing a foamable inorganic raw material on a belt conveyor running in the furnace, a cooling zone in the firing furnace includes at least one rotatable member rotating in contact with the upper and lower surfaces of the foam board. A pair of rolls are provided, the belt conveyor separates from the foam board just before the first roll, and runs on the outside of the roll, and the roll cools the foam board with a fluid passed through the inside of the belt conveyor. Foam board firing furnace. 4. The firing furnace according to claim 3, wherein the ambient temperature of the cooling zone is 350 to 900°C.