JPH0437026B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method of heating an extruded product made by continuously extruding a clay-based raw material in a predetermined shape in a microwave for a short period of about 10 minutes to 1 hour. This invention relates to a quick drying device for clay molded bodies that can be dried by using far infrared rays and air in combination due to their synergistic effect. [Prior Art] In general, inner and outer wall materials and roof tiles made of clay are extruded into a predetermined shape, and then immediately cut into short pieces, e.g.
It was common to use equipment that cut the material into lengths of ~30 cm, reduced the moisture content to 1 to 0% in about 1 to 3 days using waste heat from the kiln, and then supplied the cut to the kiln. . [Problems to be solved by the invention] Not only does the conventional drying device for clay molded bodies require several days to dry, but also the clay molded bodies, which are longer than before, cannot be transported without the use of an underboard. ,
In addition to being inferior in productivity and increasing costs,
It required a vast area. In addition, the drying time is 11% using conventional drying equipment that applies heat from the surface.
When the number of days is shortened, the surface layer dries first, and the roof tiles, tiles, and exterior wall materials may become twisted, warped, cracked, or destroyed due to the internal water vapor pressure. It was extremely difficult to shorten the time. In addition, instead of drying by heating from the surface, drying by internal heating devices such as microwave heaters and far-infrared heaters can be considered, but if each device is simply used, the former can heat the material to about 130℃. They were difficult to raise, rapid heating could lead to explosions, and the equipment and energy costs were more expensive than the latter. In addition, although the latter takes longer to reach the inside of the material to be dried than the former, it is much more advantageous in raising the internal temperature than the former, so each drying device has its advantages and disadvantages. Moreover, in the above two devices, the large amount of water vapor generated during drying is treated to prevent condensation.
There are also various problems with the conveying structure during drying of the dried material, such as frictional resistance between the dried material and the conveyor belt, non-uniform heating of the elongated body by microwaves, etc. [Means for Solving the Problems] In order to eliminate such drawbacks, the present invention uses an extrusion molding machine, a microwave heating machine that has good penetration into the inside of the extruded product, and then a microwave heating machine that has good penetration into the inside of the extruded product, and then In addition to arranging far-infrared heater devices that use rising infrared rays (far-infrared rays) as a heat source, a large amount of air is supplied to the space to be heated by microwave heating to remove a large amount of water vapor generated during drying. The continuum of clay extrudates is heated continuously for about 10 minutes by releasing air by air supplied or sucked out of the heating space to eliminate condensation on the surface of the extrusion and adhesion of condensed water to the inner walls of the heating space. To propose a device for rapidly drying clay molded objects, which can be dried in a short time of about 1 minute to 1 hour, and which is much more compact than before, and which can quickly dry the object to be dried without cracking, warping, twisting, or exploding. It is. [Example] Hereinafter, an example of the quick drying device for clay molded bodies according to the present invention will be described in detail with reference to the drawings. FIGS. 1a and 1b are explanatory diagrams showing a typical example of the above-mentioned apparatus. In the figure, reference numeral 1 denotes an extrusion molding machine that continuously extrudes a clay-based raw material into an extrusion molded product A having the cross-sectional shape shown in Figure 2 a to j. It varies depending on the speed, but it is about 200 to 2000 mm/min. Note that clay is a natural product and has different components depending on its production area, and these advantages and disadvantages are offset to obtain a predetermined mixed clay. Specific examples include potter's stone, feldspar, kaolinite, hallosite, metahalosite, Kibushi clay, Frogme clay, Shigaraki clay, and Shamotsu clay, which are crushed and kneaded by adding water. In addition, iron may be removed from this clay using a magnet if necessary.
Reference numeral 2 denotes a transfer mechanism, which is composed of at least one type of, for example, a free roller or a drive belt (not shown) that is synchronized with the extrusion speed, and is used to feed the extruded product A to the next process at the same extrusion speed without deformation. It is something. 3 is a microwave heating machine with a continuous oven structure, which mainly penetrates into the interior of the extruded product A and converts microwaves into thermal energy without requiring time for heat conduction.
It generates heat in a few seconds to a few minutes to evaporate the moisture in the clay. In addition, the extruded product A contains about 22 to 15% water by weight,
It has the ability to evaporate, for example, 5 to 10% of that amount. In particular, this type of extruded product A shrinks in volume until the moisture content reaches about 5 to 8%, but when the moisture content falls below that, the volume does not shrink. Therefore, to explain the microwave heating device 3 in detail, a waveguide 4 guides microwaves oscillated from a microwave oscillator (not shown) to a desired location.
and a reflecting plate 5 that reflects the guided microwave B.
and a rotating blade 6 that stirs the reflected microwaves.
, a conveying section 7 consisting of a free roller having a dielectric but non-sparking structure that moves the extruded body A at an extrusion speed, an inlet and an outlet 8 of the extruded body A,
9, an air supply port 13 that sucks a large amount of air, etc. This is what I did.
Note that the inlet and outlet 8, 9 are formed to have a structure and length that also function as a filter to prevent the microwave B from leaking to the outside. Further, the space to be heated 12 in which the extrusion molded product A is heated varies depending on the purpose, but is, for example, about 1 to 5 m. Furthermore, the conveyance section 7 uniformly irradiates or sends microwaves B, air, etc. C to the extrusion molded product A,
When the extrusion molded product A dries, about 10% of the entire shrinkage occurs, so the structure is such that the extrusion molded product A can be transported while absorbing this shrinkage. To illustrate an example, as shown in FIGS. 3a and 3b, a pipe-shaped free roller 7 made of a fixed core rod 7a and Teflon is shown.
It is composed of a core rod support 10 as shown in FIG. 4, and a shielding plate 11 provided as necessary. To explain further, in figure a, the width of the free roller 7b is divided into three parts to reduce the resistance when the extruded body A passes through, and in figure b, the free roller 7b is composed of one piece. In addition, the core rod support 10 is provided with a passage hole 10a so that the microwave B can be irradiated from the back side of the extrusion molded body A as well. In addition, when the extrusion molded body A is a long body, the shielding plate 11 is
This is useful for achieving uniform heating by suppressing high density physically at both ends in the longitudinal direction. In addition, the air supply port 13 is provided with air (dry air, warm air, etc.) from a compressor, ring blower, etc.
It is connected to an air cycle prime mover 15 that can blow or suck air (including air). 16 is a far infrared heater device that uses infrared rays, especially far infrared rays, as a heat source, and reduces the moisture content of extruded product A to 1 to 0.
In order to reduce the temperature to 130%, the temperature of extrusion molded body A was
It raises the temperature to above ℃. Its structure consists of a conveyance mechanism 17 consisting of free rollers and a drive belt, a far-infrared heater 18, and a heat insulation box 19, and the heating zone is about 2 to 10 meters. Of course, the heating zone varies depending on the thickness, width, size, and conveyance speed of the semi-dry extrusion molded body A. Next, the operation will be explained. First, clay consisting of Shigaraki clay, Shiyamotsuto, a water reducing agent, and water is prepared as a raw material. The weight percentage is, for example, 61.5% Shigaraki clay, 18% Siyamoto, 0.5% water reducer (product name: Cellflow, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and 20% water in a clay kneading machine (model MP-100 manufactured by Miyazaki Iron Works Co., Ltd.). ). In addition, extrusion molding machine 1
The model name MV has an extrusion capacity of 100 to 150/hr.
-FM-A-1 type (manufactured by Miyazaki Tekko Co., Ltd.) was used. In addition, the transfer mechanism 2 has a free roller and a drive belt conveyor arranged in that order, the microwave heating device 3 has a frequency of 2450 MHz, an output of 5 kW, and a heated space 12 of 3 m in length. A large amount of water vapor C' is fed into the space 12 from one wall surface of the enclosure 14, and the water vapor C' generated during heating is released from the inlet and outlet 8, 9 to the outside, reducing the water vapor pressure in the space 12 to be heated, and The structure is such that it is possible to prevent dew condensation from forming on the inner wall of the enclosure 14, and the conveying section 7 is a free roller made of a Teflon pipe. In addition, far infrared heater device 16
is one in which a plurality of far-infrared heaters 18 are arranged in a zone of about 3 to 10 meters, and the output is, for example,
It was set to 20kw. Note that the microwave heater 3 was set to evaporate 18% (wt%) of water in the extruded body A to 5% (wt%), and the remaining water was evaporated by the far-infrared heater device 16. Furthermore, the extrusion speed of the extrusion molding machine 1 was 300 to 1000 mm/min, and was set to 400 mm/min here. In addition, the pass lines of the extrusion molded product A (here, a continuous molded product) are set at the same height, and the extrusion molded product A is fed to the microwave heating machine 3 by a drive belt at the same extrusion speed of the extrusion molding machine 1. The volume shrinks due to moisture evaporation on the free roller of the conveying section 7 in the microwave heating device 3 , but this is designed to absorb the difference in speed. Therefore, the clay supplied to the extrusion molding machine 1 is delivered from its outlet in a continuous body having a cross section shown in FIG. 2g. The delivered extrusion molded product A is sent to the microwave heating machine 3 via the transfer mechanism 2, and while passing through the heated space 12 of the microwave heating machine 3 , the moisture content of the extrusion molded product A is reduced to 5% (weight ratio). ) up to 5
The water was reduced in about 10 minutes, and then sent from the outlet to the far-infrared heater device 16, where the water was evaporated to 1% (weight ratio) and dried in about 10 minutes. As a result, an extruded product A with a continuous band extending from the exit of the extrusion molding machine 1 to the far-infrared heater device 16
could be sent to the next process as a dry product in about 15 to 20 minutes. The following effects can be obtained by releasing the water vapor C' in the space to be heated 12 from the inlets and outlets 8 and 9 in the direction of the arrows. That is, the release of air from the heated space 12 prevents the water vapor pressure in the heated space 12 from increasing, prevents the extruded product A from overheating and breaking due to rapid heating, and releases air etc. cools the exposed surface of the extrusion molded product A by giving a flow to the air layers near the front and back surfaces of the extrusion molded product A during heating, and together with this, suppresses overheating and shortens the drying time. , exposed surface of extrusion molded body A, heated space 12
This prevents condensation from forming on the inner walls of the Then, this dried continuous band-shaped extrusion molded product A is cut into regular lengths by a running cutter 20 and sent to a glazing process or a firing process (not shown). What has been described above is only one embodiment of the quick drying device for clay molded bodies according to the present invention, and a cutter is provided at the position shown by the dashed line in the transfer mechanism 2 portion in FIG. As shown by the dotted line, a microwave heater 3 and a far-infrared heater device 16 are installed.
It is also possible to supply warm air or hot air to the far-infrared heater device 16 (shown only in the far-infrared heater device 16) to further shorten the drying time. It is also possible to provide an air cycle line in addition to or in place of the air supply port 13, as shown by the dashed line in the microwave heating device 3 in FIG. 1a. [Effects of the Invention] As described above, according to the quick drying device for clay molded bodies according to the present invention, the moisture content can be reduced to about 22 to 15% (weight ratio).
Cracking, explosion,
No warping or twisting, and the drying time is 1/10 of the previous one.
It has the feature that it can be shortened to 0-300. Further, although the volume of the extruded body shrinks by 10% or more compared to when it is extruded, there is an advantage that the transport speed due to this shrinks without any adverse effect on the extruded body and can be absorbed and transferred to the next process. Furthermore, in the present invention, since the processes from extrusion to drying are arranged in series, a long band or continuous band can be dried quickly. Furthermore, since the water vapor in the space to be heated is released to the outside, it is possible to prevent an adverse effect on the inner wall of the space to be heated and the surface of the object to be heated, to prevent condensation, and to prevent a decrease in the evaporation speed.
Furthermore, by irradiating the heated object with microwaves from below, concentrating on the weakly heated portion, etc., it is possible to achieve uniform drying and prevent adverse effects during drying.

[Brief explanation of drawings]

Figures 1a and 1b are schematic structural diagrams showing one embodiment of the quick drying device for clay molded bodies according to the present invention, and its cross-sectional view taken along the line A--A, and Figures 2 a to j are explanatory diagrams showing cross-sections of extruded molded bodies. 3A, 3B, and 4 are explanatory diagrams showing the structure of the conveying section of the microwave heating machine. 1... Extrusion molding machine, 3 ... Microwave heating machine, 7...
Conveyance section, 13... Air supply port, 16... Far infrared heater device, A... Extruded body, B... Microwave, C...
Air, C′...water vapor.

Claims (1)

[Claims] 1. An extrusion molding machine that continuously extrudes a clay-based raw material into a predetermined shape, and a continuous oven type microwave heating machine that quickly reduces the moisture content of the extruded product sent out from the extrusion molding machine. A far-infrared heater device is arranged in order to mainly raise the temperature of the extruded product that has passed through the microwave heating machine, and an air supply port is provided on the outer peripheral surface other than the exit and inlet of the microwave heating machine, Furthermore, the apparatus for quickly drying a clay molded body is characterized in that the conveyance section for the extrusion molded body between the microwave heating devices is comprised of a free roller.