JPH0676220B2 - Method for manufacturing foam plate and firing furnace used therefor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a foam plate and a firing furnace used therefor.

More specifically, the foamed plate after firing is pressed while being rapidly cooled by the direct contact of the pressure cooling means, and then the surface stress of the foamed plate is re-raised to alleviate the strain stress in the foamed plate, resulting in excellent performance. The present invention relates to a foamed plate manufacturing method capable of obtaining a foamed plate and increasing a production rate, that is, productivity by rapidly cooling, and a combustion furnace used for the method.

[Prior Art] Conventionally, foamed plates have been widely used in prefabricated houses and the like because they are lightweight, easy to handle, and excellent in heat retention, fire resistance, and durability.

Such foam plate is generally made of natural glass, artificial glass, porous volcanic rock, igneous rock, sedimentary rock, tuff, etc. as main raw materials,
These can be obtained by heat-foaming them, and then pressing the obtained foam plate with a pressure roll or the like to fuse them and simultaneously molding. The above steps are usually performed continuously in the furnace, and the expansive substance supplied onto the belt running in the furnace is heated, fired, and cooled, and then the foamed plate having a desired shape is obtained. Is discharged from the furnace.

By the way, when the surface of the foamed plate is rapidly cooled in the cooling step, the temperature near the surface rapidly drops, and the temperature distribution in the vicinity of the surface and in the interior becomes uneven, so that tensile stress is generated near the surface and compression is generated inside. There is a problem that stress is generated and the foam plate is damaged by these stresses.

In particular, there is a problem that thermal strain stress is likely to occur between the annealing point and the strain point, the temperature nonuniformity in the thickness direction of the foam plate becomes several degrees Celsius or more, and the foam is damaged by the heat stress.

Therefore, in order to prevent damage to the foam plate due to such thermal stress, conventionally, a method of blowing air on the upper surface and the lower surface of the foam plate has been adopted as a cooling method, and in this case, the temperature distribution of the foam plate is uniform. In order to maintain the property, the cooling time is set long and the foam plate is gradually cooled.

Further, as shown in Japanese Utility Model Publication No. 53-50759, the foam plate was pressed against the lower surface of the foam plate via a belt conveyor.

[Problems to be Solved by the Invention] However, the cooling method by air blowing described above is
There is a problem in that the cooling rate cannot be set fast and therefore it takes a long time to cool, which is a major obstacle in increasing the production efficiency of the foam plate.

This problem becomes more remarkable as the thickness of the foam plate increases and the weight of the cooling time that can be included in the entire process time increases.

Furthermore, in the conventional method, since the foam plate is pressed against the bottom surface of the foam plate via the belt conveyor, there is a problem that the dimensional accuracy in the thickness direction becomes low and the bottom surface of the foam plate cannot be smooth. there were.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for manufacturing a foam plate in which the drawbacks of the conventional example are eliminated and a firing furnace used therefor. That is, by directly quenching the foam by a pressure cooling means such as a roll, the cooling time can be shortened, and thus the production efficiency can be improved and the cost of the product can be reduced, and the belt conveyor can be used. An object of the present invention is to provide a method for producing a foam plate having high dimensional accuracy in the thickness direction and having excellent smoothness along with the upper and lower surfaces by directly pressing the foam plate without intervention, and a firing furnace used therefor. . In that case, the occurrence of thermal stress due to rapid cooling is mitigated by eliminating the uneven temperature distribution of the foam plate by raising the surface temperature again after passing through the strain temperature atmosphere after quenching, so the foam plate is damaged. There is nothing to do.

[Means for Solving Problems] In the production method of the present invention, when a foamable inorganic raw material is heated and pressed in a firing furnace to produce a foam plate, the method is provided in a cooling zone in the firing furnace, and The foamed plate after firing is rapidly cooled by a pressure cooling means that is in direct contact with the upper surface and the lower surface of the foamed plate, and then the surface temperature of the foamed plate is set to an ambient temperature of 350 to 9
It is characterized in that the temperature is raised again in the atmosphere of the cooling zone which is 00 ° C.

The firing furnace of the present invention is a continuous firing furnace that heats and presses a foamable inorganic raw material on a belt conveyor running in the furnace to form a foam plate, and the firing furnace has an inlet from an outlet. A temperature raising zone, a firing zone and a cooling zone are provided in that order, and the cooling zone is provided with at least a pair of cooling rolls that rotate in direct contact with the upper surface and the lower surface of the foam plate. A fluid for cooling the foam plate is flowing inside, the belt conveyor runs outside the roll separated from the foam plate immediately before the first cooling roll, and the furnace immediately after the last cooling roll. It is characterized in that a transport roll for transporting the foam plate is provided up to the vicinity of the outlet.

[Operation] In the method for producing a foamed plate of the present invention, the foamed plate is rapidly cooled by a roll that rotates in direct contact with the upper surface and the lower surface of the foamed plate, and is passed through a strain temperature atmosphere after being rapidly cooled. Then, the surface temperature rises again and the non-uniformity of the temperature distribution of the foam plate is eliminated, so that the occurrence of thermal stress due to rapid cooling is mitigated.

Moreover, since the upper surface and the lower surface are directly pressed by the rolls, uniform and reliable pressing is performed.

[Examples] Next, a manufacturing method of the present invention and a firing furnace used therein will be described with reference to the drawings.

FIG. 1 is a schematic explanatory view showing an embodiment of the firing furnace of the present invention. In the figure, (1) is a firing furnace, and a belt conveyor (3) for carrying a foam plate (2) is installed in the firing furnace (1). The belt conveyor (3) is preferably a mesh-shaped one in order to uniformly diffuse the volatilized components at the time of foaming from the upper and lower surfaces and to uniformly transfer heat to the upper and lower surfaces. For example, a stainless mesh belt is coated with ceramic. A thing, a ceramic belt, etc. are used.

As the expandable inorganic raw material that is the object to be fired, a pelletized mixture of natural glass, artificial glass, porous volcanic rock, igneous rock, tuff, etc. is used, and the pellet is fed from a supply hopper (4) to a belt conveyor ( 3) An appropriate amount is supplied on top. The supplied pellets are leveled by the spare roller (5) to have a substantially uniform thickness and fed into the firing furnace (1). After that, the pellets are heated in the heating zone and then heated in the firing zone to foam.
The temperature rise depends on the particle size and blending of the raw materials, but is not particularly limited in the present invention as long as the temperature rises at a rate of 80 ° C. for 1 minute. The firing temperature also varies depending on the particle size of the raw material, the foaming rate, the uniformity of the pore diameter of the raw material, etc., as in the case of raising the temperature, but a rule of thumb is 700 to 1100 ° C. Further, 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 following the above firing step. That is, the foam plate (2) foamed by firing is a pressure cooling roll (6) which is a pressure cooling means.
It is cooled by being pressed by the fusion molding and at the same time, but at this time, the center portion or middle layer portion of the foam plate (2) is softened by the direct contact between the roll (6) and the foam plate (2). It is performed rapidly within the range of not less than the point. In that case, the thermal strain stress generated by the rapid cooling on the surface of the foam plate (2) is relaxed by allowing the foam plate (2) to pass through a strain temperature atmosphere after cooling and raising the surface temperature again. (2) is not damaged.

In the conventional cooling method by blowing air, the air blown to the foam plate (2) cools the foam plate (2) and diffuses into the furnace, so that the atmosphere in the furnace on the outlet side from the cooling position is the atmosphere. Lower the temperature. Therefore, the foam plate once cooled is gradually cooled to the ambient temperature of the furnace without being heated again after being cooled and is carried out of the furnace. However, since cooling in the present invention is contact cooling by the pressure cooling roll (6), there is no flow of cold air into the furnace. Therefore, the surface of the foamed plate (2) after the rapid cooling can be raised again depending on the ambient temperature, and the thermal strain stress due to the rapid cooling can be relaxed. That is, after being rapidly cooled by the pressure cooling roll (6), the center portion or middle layer portion of the foam plate (2) is at the softening point or the cooling point, while the surface is fixed by the contact quenching and tensile stress is generated. By the reheating, the stress is relieved, and the heat of the central portion or the middle layer portion is transferred to the surface to accelerate the uniformization of the temperature of the foam, so that the heat strain stress is relieved.

A fluid such as water or air can be used as a cooling source of the pressure cooling roll (6). The surface temperature of the roll (6) may be determined in consideration of the temperature, viscosity, production speed, etc. of the foam plate (2) and can be set arbitrarily. The temperature control may be carried out, 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, of course, the surface temperature of the roll (6) can be adjusted by a control method other than the above.

In the pressure cooling step described above, the foam plate (2) is separated from the belt conveyor (3) immediately before the pressure cooling roll (6), and both the upper surface and the lower surface are directly fed by the roll (6), that is, the belt conveyor (3). (2) Since the pressure is applied without passing through, it is possible to make both surfaces of the foam plate (2) smooth.

As shown in FIG. 1, the foam plate (2) is pressure cooled by the pressure cooling roll (6), and then moves on the transport roll (7) toward the exit of the furnace.

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

The atmosphere temperature in the firing furnace is preferably in the range of 350 to 900 ° C. from the viewpoint of gradual cooling and re-heating of the foam plate (2). The optimum value within this range is determined according to various conditions such as the type of raw material of the foam plate (2) and the moving speed of the belt conveyor (3), but in order to achieve the object of the present invention, foaming is performed. It is necessary to set it above the transition temperature of the body (2).
The optimum value of the surface temperature of the roll is also determined according to the type of raw material of the foam plate (2), the moving speed of the belt conveyor (3), and the like.

In the present invention, the cooling is performed by the rolls within the range where the center or middle layer of the foam plate (2) does not become lower than the softening point. Occurs, and a compressive stress is generated inside.

After the rapid cooling, when the foam plate (2) is at a high temperature above the softening point, the thermal stress is relieved in a short time and becomes stress-free in spite of the temperature difference between the surface and the inside, but is gradually cooled. It is not preferable because it takes time. In the present invention, by cooling the foam plate (2) again in the transition temperature atmosphere, cooling can be performed safely and in a short time.

Next, the production method of the present invention and the firing furnace used therefor will be explained based on examples, but the present invention is not limited to these examples.

Example 1 Nagano clay 82.5% (weight%, the same applies hereinafter), soda ash 12%,
Raw material consisting of 5% dolomite and 0.5% SiC (softening point: 680
C., transition point 630.degree. C.) was mixed and granulated, and the mixture was supplied from a supply hopper onto a belt conveyor and fired under the following conditions. For cooling after firing, a contact quenching method using a pressure cooling roll was adopted.

Baking temperature: 1020 ℃ Temperature inside the foam after quenching: 730 to 680 ℃ Ambient temperature in the furnace after cooling and pressurizing: 650 to 630 ℃ Moving speed of the conveyor: 28cm / min The foamed plate cracked on the surface There was no such occurrence, and both the front and back sides were in a homogeneous and smooth finished state.

Second, the relationship between the manufacturing time and the surface temperature of the foam in Example 1 is
Shown in the figure.

In FIG. 2, (a) shows the firing start point, (b) shows the cooling start point, (c) shows the cooling end point, and (d) shows the exit point of the furnace. As is clear from FIG. 2, the surface temperature of the foam plate is rapidly lowered by the contact cooling by the rolls, but is increased again after being cooled by the rolls. After that, the temperature gradually decreased again, and it took 90 minutes to reach the predetermined temperature (120 ° C).

Example 2 Nagano clay 64.5%, glass powder 30%, dolomite 5%, SiC
A raw material consisting of 0.5% (softening point D: 720 ° C., transition point: 630 ° C.) was blended and granulated, and the mixture was fed onto a belt conveyor from a feed hopper, and fired under the following conditions. For cooling after firing, contact rapid cooling with a pressure cooling roll was adopted.

Firing temperature: 1050 ℃ Temperature inside the foam after quenching: 770-720 ℃ Ambient temperature in the furnace after cooling and pressurizing: 680-630 ℃ Moving speed of conveyor: 28cm / min The foamed plate cracked on the surface There was no such occurrence, and both the front and back sides were in a homogeneous and smooth finished state.

Example 3 Glass powder 50%, silica stone powder 20%, borax 14.5%, Nagano clay 10
%, 5% sodium silicofluoride, and 0.5% SiC (softening point: 580 ° C, transition point 480 ° C) are blended and granulated, and then the mixture is supplied from the supply hopper onto the belt conveyor under the following conditions. Firing was performed. For cooling after firing, a contact quenching method using a pressure cooling roll was adopted.

Firing temperature: 730 ℃ Temperature inside the foam after quenching: 630 to 580 ℃ Ambient temperature in the furnace after cooling and pressurizing: 550 to 480 ℃ Conveyor moving speed: 28 cm / min The foamed plate cracked on the surface There was no such occurrence, and both the front and back sides were in a homogeneous and smooth finished state.

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

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

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

Cracks as shown in FIG. 4 were recognized on the surface of the obtained foam plate.

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

Cracks as shown in FIG. 5 were recognized on the surface of the obtained foam.

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

The obtained foam plate had no cracks on the surface, and both the front and back surfaces were in a homogeneous finished state.

Second, the relationship between the manufacturing time and the surface temperature of the foam in Comparative Example 4 is
Shown in the figure. As is clear from FIG. 2, the surface temperature of the foam plate is rapidly lowered by cooling by blowing air, and is gradually lowered by natural cooling after blowing. It took 130 minutes to reach the prescribed temperature (120 ° C).

Comparative Example 5 A foam plate was produced in the same manner as in Example 2 except that the air blowing method was used for cooling after firing and the moving speed of the conveyor was 17 cm / min.

The obtained foam plate had no cracks on the surface, and both the front and back surfaces were in a homogeneous finished state.

Comparative Example 6 A foam plate was prepared in the same manner as in Example 3 except that an air blowing method was adopted for cooling after firing, the lower surface of the foam plate was pressed through a belt conveyor, and the moving speed of the conveyor was 21 cm / min. Was manufactured.

The obtained foam plate had no surface cracks, but the lower surface was inferior in smoothness to Example 3.

From FIG. 2, according to the manufacturing method of the present invention, it is possible to lower the surface temperature of the foam to a predetermined temperature in a short time as compared with the conventional manufacturing method which employs the cooling method by blowing air. Recognize.

[Effects of the Invention] As described in detail above, according to the manufacturing method and the firing furnace of the present invention, the cooling rate can be increased without causing damage to the foam plate due to thermal strain stress. That is, it becomes possible to shorten the manufacturing time from the temperature rise to the cooling and improve the production efficiency, and thereby reduce the cost of the product.

Further, since the pressure cooling is performed directly from both sides of the foamed plate by the roll, it is possible to obtain a foamed plate which is excellent in dimensional accuracy in the thickness direction and is homogeneous and smooth on both sides.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of a firing furnace of the present invention,
FIG. 2 is a diagram showing the relationship between the manufacturing time and the surface temperature of the foam plate in Example 1 of the present invention and Comparative Example 4, and FIGS.
FIG. 5 is a view showing the surface condition of the foam plates manufactured in Comparative Examples 1 to 3, respectively. (Main symbols in the drawing) (1): Baking furnace (2): Foam plate (3): Belt conveyor (6): Pressurized cooling roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takatoshi Miyazawa 1-1-12 Shinsenri Nishimachi, Toyonaka City, Osaka Prefecture National Housing Industry Co., Ltd. (56) References

Claims (3)

[Claims] 1. When a foamable inorganic raw material is heated and pressed in a firing furnace to produce a foamed plate, a heating plate provided in a cooling zone in the firing furnace and directly contacting an upper surface and a lower surface of the foamed plate. A method for producing a foam plate, characterized in that the foam plate after firing is rapidly cooled by a pressure cooling means, and then the surface temperature of the foam plate is raised again in the atmosphere of the cooling zone in which the ambient temperature is 350 to 900 ° C. . 2. A continuous firing furnace in which a foamable inorganic material is heated and pressed on a belt conveyor running in the furnace to form a foam plate, and the firing furnace is sequentially elevated from an inlet to an outlet. A temperature zone, a firing zone, and a cooling zone are provided, and the cooling zone is provided with at least a pair of cooling rolls that rotate in direct contact with the upper surface and the lower surface of the foam plate. A fluid for cooling the foam plate is flowing, the belt conveyor runs outside the roll separated from the foam plate immediately before the first cooling roll, and,
A foam plate baking furnace, characterized in that a carrier roll for carrying the foam plate is provided immediately after the last cooling roll to near the exit of the furnace. 3. The firing furnace according to claim 2, wherein the ambient temperature of the cooling zone is 350 to 900 ° C.