JPH0133533B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat insulating cover for high temperature steel material being transported on a roller table. In the conveyance line for high-temperature steel materials, as shown in the schematic cross-sectional view of the conveyance line in FIG. It is installed so as to cover the high temperature steel material 3 being conveyed by the rollers 2. The heat insulation cover 1 is for preventing cooling of the high-temperature steel material 3 being transported, and as shown in the partially enlarged sectional view of FIG. It is formed from a steel plate jacket 5 provided on the outside. The high-temperature cover 1 prevents the radiant heat emitted from the high-temperature steel material 3 from dissipating, and also heats its inner surface to a high temperature due to the radiant heat from the high-temperature steel material, thereby reducing the amount of heat exchange between the high-temperature steel material and this inner surface. The purpose is to reduce the size and prevent cooling of high-temperature steel materials. By the way, in the past, there have been the following difficulties in keeping heat in a conveying line for high-temperature steel materials. (1) High-temperature steel materials are transported intermittently, and the time interval between transports is relatively long. For example, if we take a high-temperature slab as a high-temperature steel material, the length of the slab is generally several meters to several tens of meters, and it is transported at a speed of several meters/min to 120 m/min at intervals of one to several minutes. There is. Therefore, if a slab with a length of 10 m is 120
When conveying at a speed of m/min, the time that any part of the insulation cover faces the slab is:
It is very short, 5 seconds every 1 to several minutes. As a result, even if the inner surface of the thermal cover becomes hot when a high-temperature slab passes through it, the temperature drops before the next high-temperature slab passes, so it is inevitable that the high-temperature slab being transported will cool down. . The degree of cooling is greater as the tip of the hot slab passes through the inner surface of the insulation cover, where the temperature has decreased, and decreases as the rear end of the hot slab passes through the insulation cover, whose temperature has increased due to radiant heat as the high temperature slab passes through. Become. (2) The atmosphere around the heat insulating cover contains a lot of moisture due to the cooling water supplied to the bearings of the conveyor rollers, rolling rolls, etc., and this moisture may have an adverse effect on the heat insulating cover. give.
For example, insulating bricks, castables, ceramic fibers, etc. are used as the insulating material that makes up the heat insulating cover, but when moisture enters the insulating material, the thermal conductivity of the insulating material decreases to about 10 rise twice. Therefore, the radiant heat generated by the high-temperature steel material is easily radiated to the outside through the heat-insulating cover, so that the high-temperature steel material is cooled.
Furthermore, if moisture enters the insulation material, the insulation material will deteriorate and the thermal cover will no longer be able to withstand long-term use. Therefore, in order to prevent moisture from entering the heat insulating material, a heat insulating cover with a protective plate 6 provided on the side of the heat insulating material 4 facing the high-temperature steel material is installed, as shown in the partially enlarged sectional view of FIG. Are known. usually,
The protection plate 6 has a thickness of 0.8 in consideration of thermal deformation.
A relatively thick steel plate of mm or more is used. However, such a heat retaining cover using a relatively thick steel plate for the protection plate 6 has a small heat retaining effect as described later. Further, a heat-retaining cover using a metal plate with low emissivity (high reflectance) as the protection plate 6 is also known. However, with this thermal cover, the metal plate surface deteriorates due to moisture adhering to the metal plate, and due to oxidation due to long-term use, the low emissivity (high reflectance) of the metal plate cannot be maintained, so it is not effective at retaining heat. almost disappears. In view of the above-mentioned difficulties, the present inventors conducted tests on the heat insulating structure of a heat retaining cover in order to develop a heat retaining cover that has a high heat retention effect on high-temperature steel materials being transported. As a result, we found the following. In the test, a high-temperature slab of 1000°C was inserted into various heat insulation covers whose partially enlarged cross-sectional views are shown in Figures 4a to d, and the normal rate of decrease in the surface temperature of the slab was measured from immediately after insertion until 5 seconds had elapsed. Examined. Figure 4 a-d
The heat insulation cover shown in Figure a has a structure made of a single steel plate 7 with a thickness of 0.8 mm, Figure b shows a structure in which ceramic fibers 8 are stacked on the steel plate 7, Figure c shows a structure in which ceramic fibers 8 are stacked on the steel plate 7,
A structure in which a low emissivity plate (emissivity: 0.1 to 0.20) 10 made of a chrome-plated steel plate is provided through a gap 9,
d in the same figure is a steel plate with a thickness of 0.01 mm or SUS310S (25C-
It has a structure in which 20 metal plates 11 made of (20Ni) are stacked. The results were as shown in Table 1.

[Table] According to Table 1, the rate of temperature drop on the slab surface is approximately 40% when using the insulation covers shown in Figure 4 a to c compared to when there is no insulation cover, which is natural cooling.
%, but there is no big difference in the rate of descent of the slab surface between the insulation covers shown in Figure 4 a to c. On the other hand, when the insulation cover shown in Figure 4 d is used, , it was about 1/20 of the thermal cover shown in Fig. 4 a to c. From the above test results, the heat retention characteristics of the slab by the heat insulation cover are determined by the temperature rise rate of the steel plate 7 and the metal plate 11 facing the slab of the heat insulation cover, and It turns out that it is controlled by thickness. In other words, if a thin metal plate is provided on the side of the insulation cover facing the slab, the metal plate will heat up to a high temperature in a short time due to the radiant heat emitted by the high-temperature slab, and the slab will heat up. The amount of radiant heat lost will be reduced and the slab will be kept warm. Next, in order to quantitatively investigate the influence of the thickness of the metal plate on the heat retention effect, we examined
We created 5 types of thermal covers with a structure consisting of 5 layers of 0.3 mm and 0.5 mm steel plates, and placed them inside the thermal cover.
A 1000°C slab was inserted, and from the moment it was inserted, the temperature change over time in the surface temperature of the slab side of the heat insulation cover was measured. Then, from the measured temperature, calculate the heat radiation amount of the slab inside the heat insulation cover, and from that heat radiation amount and the heat radiation amount of the slab during natural cooling,
The insulation efficiency η of the heat insulation cover was determined according to the following formula. Insulation efficiency η = (1 - heat radiation amount of the slab inside the heat insulation cover / heat radiation amount of the slab during natural cooling) × 1100 (%) Figure 5 shows that after inserting the slab into the heat insulation cover,
This is the insulation efficiency η of the heat insulation cover after 1 second and 3 seconds have elapsed. According to Figure 5, when 1 second has passed after inserting the slab, if the metal plate exceeds 0.1 mm, the insulation efficiency is almost constant and low, and if the plate thickness is 0.1 mm or less,
The insulation efficiency is increasing rapidly. After inserting the slab 3
A similar trend in insulation efficiency can be seen when the plate thickness exceeds 0.1 mm. Therefore, it was found that using a metal plate with a thickness of 0.1 mm or less for the heat insulation cover greatly increases the heat insulation effect. This invention was made based on the above knowledge, and the heat insulation cover of the invention is made of a metal plate made of one or more metal plates with a thickness of 0.1 mm or less, facing the high-temperature steel material being conveyed on a roller table. It is characterized in that it is composed of a plate layer and a heat insulating material layer provided on a side of the metal plate layer opposite to the side facing the high temperature steel material. In this invention, the metal plate forming the metal plate layer facing the high-temperature steel material of the heat insulating cover needs to have a thickness of 0.1 mm or less, based on the above test results. When the thickness of the metal plate exceeds 0.1 mm, the heat insulation efficiency of the metal plate reaches a certain low value, and the heat insulation effect of the heat insulation cover becomes small. In this case, it is better to use a metal plate that is as thin as possible for better heat retention. FIG. 6 is a partially enlarged sectional view showing one embodiment of the heat retaining cover of the present invention. In the same figure, 1
2 is a metal plate layer consisting of one or more metal plates with a thickness of 0.1 mm or less, and 13 is a heat insulating material layer. metal plate layer 1
For 2, a layer consisting of a single metal plate with a thickness of 0.1 mm or less is sufficient, but if the heat insulating cover is used for a long period of time, the metal plate will oxidize and partially break off, so multiple metal plates should be laminated. It is preferable to do so. When a plurality of metal plates are laminated, the thermal resistance between the metal plates has the effect of improving the heat insulation properties of the heat retaining cover. Examples of metal plates include steel plates, stainless steel plates, and others. The heat insulating material layer 13 keeps the metal plate layer 12 heated by the high-temperature steel material and helps the metal plate layer 12 to reach a high temperature in a short time. consisting of insulation material. The heat insulating material layer 13 is prevented from moisture entering into the insulating material layer 12 by the metal plate layer 12,
Thermal conductivity is prevented from increasing. FIG. 7 is a perspective view showing another embodiment of the invention. This heat insulation cover supports the metal plate layer 12 with a heat-resistant metal wire mesh 14 to reinforce the metal plate layer 12, and the heat insulating material layer 13 is supported by a steel plate outer sheath 15.
The heat insulating material layer 13 is protected. Although this invention is configured as described above,
According to this, the metal plate layer of the insulation cover where the high-temperature steel material passes through is heated by the radiant heat emitted by the high-temperature steel material, and the temperature rises to a high temperature in a single hour. Most of the time, the high-temperature steel material passes through the heated metal plate layer, so
High-temperature steel materials are sufficiently insulated.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a high-temperature steel conveyance line equipped with a conventional heat-insulating cover, FIG. 2 is a partially enlarged cross-sectional view of the heat-insulating cover in FIG. 1, and FIG.
FIGS. 4a to 4d are partial enlarged cross-sectional views of other conventional heat-retaining covers, and FIG.
A graph showing the relationship between the thickness of laminated steel plates and their insulation efficiency, FIG. 6 is a partially enlarged sectional view showing one embodiment of the present invention, and FIG. 7 shows another embodiment of the present invention. FIG. In the drawings, 1... Heat insulation cover, 2... Conveyance roller, 3...
High-temperature steel material, 4, 13... Insulating material, 5, 15... Outer cover, 6... Protection plate, 8... Ceramic fiber, 11, 12... Metal plate, 14... Heat resistant metal wire mesh.

Claims (1)

[Claims] 1. A metal plate layer consisting of one or more metal plates with a thickness of 0.1 mm or less, facing the high-temperature steel material being transported on a roller table, and a side of the metal plate layer opposite to the side facing the high-temperature steel material. A heat insulating cover for high-temperature steel material being transported on a roller table, characterized by comprising a heat insulating material layer provided on a roller table.