JPH0345887A - Roller hearth kirn - Google Patents

Abstract

PURPOSE:To facilitate transportation and baking of a heavy weight by providing a cooling air supply means for supplying cool wind at proper pressure in opening parts of one hand tube rollers opening both end sides. CONSTITUTION:An air supply pipe 1 is connected to a compressor 5 through an air flow regulating valve 3 and an outer cooler 4. Air supplied to opening parts of one hand of tube rollers 8 from a branched pipe 2 passes the tube rollers 8 to allow the air to flow out from opening parts of the other hand. A suction inlet of an air collecting pipe 6 for collecting air allowed to flow out from the tube rollers 8 is formed of a shape locking with the opening parts of the other hand of the tube rollers 8 and the air collecting pipe 6 is connected to a preheating body 7 for performing preheating of products. In addition, two plate-like materials 9 to be baked are mounted on the tube rollers 8. The air flow regulating valve 3 regulates an air flow supplied to the tube rollers 8 in accordance with the temperature distribution of a roller hearth kirn so as to reduce softening and deformation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a roller hearth kiln for quickly and economically firing ceramic products at high temperatures using forced cooling rollers, and particularly relates to a wide roller hearth kiln. The present invention also relates to a roller hearth kiln suitable for firing heavy objects.

[Prior art] No. 41! I shows the general structure of a roller hearth kiln made by the same applicant as the present application, and the technical content thereof is disclosed in Japanese Patent Publication No. 64-6394.

The furnace body 15 integrally combines an upper furnace body and a lower furnace body, has a rectangular shape having a space surrounded by durable material on all four sides, and is supported by the frame 14. The furnace body 15 is composed of a plurality of pieces having the same shape connected to each other along the longitudinal direction and having an elongated shape.

At approximately the center of the cross section of the furnace body 15, tube rollers 8 are provided which are arranged on the same horizontal plane at regular intervals approximately perpendicular to the furnace length direction (in the direction perpendicular to the plane of the paper). tube roller 8
is open at both ends and functions as a hearth, on which the object to be fired 9 is mounted and transferred.

That is, both ends of the tube roller 8 are rotatably supported by a short shaft roller 10, and the short shaft roller 10 is supported by a support block 11 fixed to the frame side. Further, the short shaft roller 10 is driven and rotated by a chain wheel 12 connected thereto. The upper and lower parts of the tube roller 8 are coated with an undisclosed technique (patent application No. 63-261645) according to the inventor's invention.
A burner 13 is installed in parallel.

The burner 13 has a hollow flame tube 16 installed between both walls of a furnace body 15, an outer cylinder 19 to which a gas pipe 17 is connected and a gas passage 18 formed therein, and an air pipe 20 connected inside. It is composed of an inner cylinder 21 having an air passage. The mixture of air and gas becomes a flame and is injected from the flame injection hole 22 of the hollow flame tube 13. Further, in order to obtain a desired temperature distribution within the furnace, the pitch and/or diameter of the flame injection holes 22 are varied.

With the above configuration, the object to be fired 9 mounted on the tube roller 8 is transferred in the longitudinal direction of the furnace, heated by the flame from the central flame tube 13, and fired.

The above-described roller hearth kiln transfers and fires flat products such as ceramics, but conventionally the kiln has been widely used only for lightweight products and has not been used for products of one weight.

Fine ceramic products such as mullite, alumina, and silicon nitride with a refractory temperature of 1600 ['C] or higher have a bending strength of 1000 [kg/c+m"1] or higher at room temperature, but these products cannot be fired. temperature is 100
If the support span of the tube roller 8 exceeds 0 ['c], hot load softening will occur if the support span of the tube roller 8 is more than 1000 [mm1], and furthermore, at high temperatures of 1000 ['C] or more, a phenomenon of rapid softening as the temperature rises can be seen. .For this reason, roller hearth kilns are only used for the lightweight products mentioned above.
For example, in the case of a heavy item such as sanitary ware, the product is placed on a refractory flat plate with a large planar area to reduce the load applied to each tube roller 8.

[Objective of the present invention: Problems to be solved] In order to transfer and fire heavy objects, physical measures such as increasing the diameter of the tube roller 8 and increasing its section modulus, and changing the material of the tube roller 8 to zirconia, for example, are required. Measures such as using a material with high thermal strength such as silicon nitride and minimizing the support span of the tube roller 8 can be considered. This is difficult and equipment costs are extremely high, and the conventional technology is beyond the scope of practical use in terms of thermal economy and productivity.

An object of the present invention is to provide a roller hearth kiln with a high-performance structure that enables transporting and firing of heavy objects without impairing the economic efficiency of the generally widely used roller hearth kiln.

[Structure of the present invention: Means for solving two problems] The applicant of the present invention developed a roller hearth kiln having a structure disclosed in the previously filed Japanese Patent Publication No. 64-6394. The rollers are arranged with a roller pitch of 80 [mm], and the support span is 1900 [m].
] The softening and deformation state of the tube roller was observed. At this time, it was confirmed that the tube roller into which outside air was blown had almost 30% less softening and deformation than the tube roller into which outside air was blown. It is also a well-known fact that the softening properties under hot load are generally due to the influence of the liquid phase that rapidly forms as the temperature rises.
Based on the above, we believe that it is possible to eliminate the influence of the liquid phase by introducing an appropriate amount of outside air into the tube roller.

The present invention was created as a result of research based on the above experiments and theory, and in the roller hearth kiln with the above-mentioned structure, cold air at an appropriate pressure is applied to one opening of the tube roller which is open at both ends. This constitutes a roller hearth kiln equipped with cooling air supply means.

[Operation] Cooled air that has been pressurized to an appropriate pressure according to the temperature field inside the furnace body is fed through one opening of a tube roller that is open at both ends. The introduced air absorbs heat from inside the tube roller and is sent out from the other opening. The delivered air may be discharged as is, but if hot air is introduced into the preheating zone via the concentrator pipe and used for preheating the product, higher performance and efficiency will be achieved.

[Example code] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a perspective view showing only a continuous main part of the roller hearth kiln of the present invention, and FIG.
It is a partial cross-sectional view showing the structure around one of the tube rollers in the figure.

The cooling air supply means for feeding cold air into the tube roller 8 is not particularly limited.

In this embodiment, as shown in FIG. 1, an air inlet pipe constructed of a manifold-shaped air supply pipe 1 having a large number of branch pipes 2 and a compressor 5 etc. connected thereto is adopted. The air supply pipe 1 is connected to a compressor 5 via an air amount adjustment valve 3 and an outer cooler 4. Air introduced from the branch pipe 2 into one opening of the tube roller 8 passes through the tube roller 8.

It is sent out from the other opening.

What is shown by the two-dot chain line is an air collecting pipe 6 for collecting the air sent out from the tube roller 8, and this suction port is formed of a shape that engages with the other opening of the tube roller 8 (Fig. l1l), the air collecting pipe 6 is connected to a preheating zone 7 for preheating the product. Furthermore, two objects 9 to be fired are mounted on the tube roller 8 .

As shown in FIGS. 2 and 4, both ends of the tube roller 8 are rotatably supported by a short shaft roller 10, and the short shaft roller 10 is supported by a support block 11. A chain wheel 12 is connected to the short shaft roller 10, and is rotated by a chain connected to a drive source shown in the figure.

With the above structure, air (cold air) compressed to an appropriate pressure from the compressor 5 and cooled to an appropriate temperature by the outer cooler 4 is sent into the tube roller 8 and sent out from the opening on the opposite side, or air It will be introduced into the preheating zone 7 via the collecting pipe 6. On the other hand, the object to be fired 9 is mounted on the cooled tube roller 8, is transferred by the rotation of the tube roller 8, and is heated and fired by the flame of the burner 3.

The air mvR regulating valve 3 is for adjusting the amount of air fed into the tube roller 8 according to the temperature distribution of the roller hearth kiln, thereby reducing softening deformation.

In this embodiment, the outer diameter d1 of the tube roller 8 is 40 [ll]
l1], the inner diameter d2 is 30 [■], the support span (1 dimension in the figure) is 1000 [mm], and the material is sintered mullite (normal operating temperature] 600 ['C]).
will be adopted. Also, the tube roller 8 has a pitch p
The materials to be fired 9 were arranged in a size of 70 mm, the transfer speed was 200 mm/min, the bottom area of the objects 9 was 300 am, and the objects weighed 40 kg and were loaded in two rows.

The following table shows a comparison with conventional products under the above conditions with different firing temperatures.

In the table, the amount of deflection is δ1 shown in Figure 3. δ2,
δ is the amount of deflection in the example.

6 indicates the amount of deflection in the conventional example.

In the table, δ1. δ2 will be the same. Firing temperature 1200
In the case of ['C], cold air with a pressure of 500 [mmAg1 was blown for 0.05 Crd1 minute per tube roller 8], and in the case of 1250 ['C], the same 3.7 [m] However, with this amount of deflection, the tube roller 8 becomes unable to be driven and cannot be used in practice, and the conventional example cannot be driven at all at 1250 degrees Celsius. On the other hand, the deflection amount δ□ of the example of the present invention is 1200 ['C] and 12
Even at 50 [''C], it was confirmed that the value was around 2.5 [mm] and normal operation could be performed.

In this embodiment, the air amount adjustment valve 3
is manually adjusted to deliver cold air at the optimum temperature and air volume. However, a single circuit temperature detection means and control mechanism are provided to automatically control the air volume adjustment valve 3 to ensure that the optimum temperature and air volume are supplied at all times. A firing operation may also be performed.

[Effects of the present invention] According to the present invention, the following excellent effects can be achieved.

1) The tube roller is cooled by blowing an appropriate amount of cold air at an appropriate temperature, and the influence of the liquid phase is reduced, so that its deformation is greatly reduced.

2) The conventional technology cannot be driven at a temperature of 1200 ['C], but the present invention can be operated normally even at a temperature higher than that, making it possible to transport and fire heavy materials unlike before.

3) Since it is a simple means of just blowing cold air into the tube roller, it can be implemented easily and inexpensively, and can be easily applied to existing roller hearth kilns.

4) The tube roller may be made of a relatively non-fire resistant material and can be formed at low cost. Additionally, by using high-grade refractory materials, roller hearth kilns can produce highly refractory products at temperatures unprecedented in the past.

5) Firing can be performed under optimal conditions by manually or automatically adjusting the conditions of the cold air blown into the product.

6) It is also possible to greatly improve the thermal efficiency of the roller hearth kiln by further utilizing the air heated by roller cooling in the preheating zone.

7) It becomes possible to design a roller hearth kiln with a wider width than before, that is, a kiln capable of firing a wide object.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the overall configuration of an embodiment of the present invention, Fig. 2 is a partial sectional view showing the structure around the tube roller of this embodiment, and Fig. 3 explains the effects of this embodiment. FIG. 4 is a cross-sectional view showing an example of a conventional roller hearth kiln. 1...' Air supply pipe, 2... Branch pipe, 3... Air amount adjustment valve, 4... Aftercooler, 5... Compressor, 6
... Air concentration pipe, 7 ... Preheating zone, 8 ... Tube roller, 9 ... To be fired, 10 ... Short axis roller, Work 1 ... Support block, 12 ... Chain wheel,
13... Burner, 14... Frame, 15... Furnace body, 16... Central flame tube, 17... Gas pipe, 18...
...Gas passage, 19...Outer cylinder, 20...Air pipe, 2
1... Inner cylinder, 22... Flame injection hole. Patent applicant Hideo Igami Figure 1 Figure 1

Claims (1)

[Claims] 1) A hollow rectangular furnace body surrounded on all sides by durable material;
At approximately the center thereof, there are provided tube rollers arranged on the same horizontal plane at regular intervals almost perpendicular to the furnace length direction, and a burner which is arranged in parallel with the tube rollers at a predetermined interval and injects a flame onto the tube rollers. In a roller hearth kiln that is formed to transfer and fire a workpiece mounted on the rotating tube roller as a hearth, cooling is performed by sending cold air at an appropriate pressure into one opening of the tube roller, which is open at both ends. A roller hearth kiln characterized by being provided with an air supply means. 2) The method according to claim 1, further comprising: a concentration pipe that is removably engaged with the other opening of the tube roller in order to concentrate the air introduced into the tube roller, and a preheating zone that communicates with the concentration pipe. Roller hearth kiln as described.