JPH0449Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention is a walking beam type heating furnace for heating materials such as metals, and the hearth moves the materials to be heated in a predetermined direction. This invention relates to a heat shielding plate for the hearth opening of a walking beam heating furnace for reducing heat loss from the hearth opening.

BACKGROUND OF THE INVENTION A walking beam continuous heating furnace is generally used to heat a steel piece such as a slab to a temperature suitable for processing such as rolling. As shown in FIG. 5, the walking beam heating furnace has an opening 2 in its hearth 1, and the hearth 3 is disposed in the opening 2. The openings 2 are large enough to allow the movement of the hearth, so for the purpose of preventing heat radiation from the openings 2 or intrusion of outside air, the openings are placed at fixed positions on the posts of the hearth 3. A heat shield plate 4 is attached to the hole.

As shown in FIG. 6, the hearth 3 performs a rectangular drive cycle consisting of a series of movements of raising, moving forward (conveying), lowering, retreating, and rising.

That is, the hearth 3 rises from the lower limit position of the rear end, receives the material to be heated 5, reaches the upper limit position, and then moves forward while remaining at the upper limit position. When it moves forward and reaches the front end position, it then descends with the heated material 5 placed thereon and reaches the lower limit position.

During this descent, the heated material 5 is supported by another support, and the hearth 3 separates from the heated material 5 and reaches the lower limit position. The hearth 3 moves from the lower limit position at the front end to the lower limit position at the rear end again, rises again from the lower limit position, places the next heated material 5 on it, and lifts it up to the upper limit position.

The hearth 3, which moves in this manner, is constantly exposed to high heat in the walking beam heating furnace.
For this reason, the heat shielding plate 4 is built up with super heat-resistant metal to provide heat shielding and to close the openings as much as possible.

That is, a heat shielding plate 4 made of a super heat-resistant metal is welded to the side surface of the post of the hearth 3, and the heat shielding plate 4 and the side surface of the hearth 3 are overlaid with super heat-resistant metal.

However, the heat shielding plate 4 has a temperature history as shown in FIG.

Each temperature measurement position A to C shown in FIG. 5 is at a high temperature, and the large temperature changes shown in FIG. It can be done. Moreover, at measurement position D, the temperature reaches 1200 to 1350°C.

Problems to be Solved by the Invention Therefore, the metal heat shielding plate 4 has the following drawbacks.

(1) Because it is used in a high-temperature atmosphere inside a furnace of 1200 to 1300°C, there are problems with high-temperature heat resistance and high-temperature oxidation resistance even if it is a super heat-resistant metal.

(2) Super heat-resistant metals are expensive, have a short lifespan of about 1 to 1.5 years due to high heat and high-temperature oxidation, and have enormous maintenance and equipment costs.

(3) Especially in ultra-high temperature areas of 1200 to 1300℃, such as the soaking zone and heating zone of a walking beam furnace,
It cannot be used practically.

(4) When replacing a heat shield made of super heat-resistant metal,
It is very troublesome to break and remove the overlay, and there have been requests to improve the workability.

Further, a ceramic heat shield plate has been proposed so that it can be used in a high temperature range, but it has the following drawbacks.

(1) Since the shape of the ceramic heat shield plate and its support structure are complex, it cannot withstand the above temperature history that the heat shield plate is subjected to, resulting in a short lifespan. or,
It is troublesome to replace the heat shield plate.

(2) Conventional ceramic heat shielding plates such as castables have the problem of heat absorption spalling from the sides of the plate, which is a drawback of irregularly shaped materials. That is, as shown in the graph of Fig. 7, the amount of temperature change △T at each temperature measurement position is 200 to 300°C at each point A, B, and C, and the average temperature difference between A and B, for example. Since the ΔT _ave is as high as 200 to 300°C and the side surface area of the plate is large, heat absorption spalling occurs particularly on the side surfaces, making the plate susceptible to cracking.

Purpose of the invention This invention was made to solve the above problems, and it has a long life without uneven heat generation even in high temperature range and severe thermal history. An object of the present invention is to provide a heat shielding plate for a hearth opening of a walking beam heating furnace that is easy to heat.

Summary of the invention Therefore, in order to achieve this purpose, the main idea of this invention is to provide a ceramic material that is installed in the opening of a walking beam heating furnace and overhangs the side of the hearth through which the material to be heated is transferred. An opening in the hearth of a walking beam heating furnace, which is characterized in that the heat shield plate has an arc-shaped end and is a thin flat plate with a thickness of 15 to 30 mm, and is further surrounded by a heat insulating material to prevent uneven heat. located on the heat shield plate.

Means for Solving the Problems As shown in FIG. 2, the heat shielding plate 17 is made of ceramic in a thin and flat plate shape (ribbed shape), and its ends are made into an arc shape. Insulating material 22, 23, 30, 3
Surround with 1,32.

In the unlikely event that the hearth 6 is repaired, the heat shield plate 17
and the insulation material (filling) together.

Function The heat shielding plate 17 is made of ceramic and is thin and flat, so it can be easily destroyed together with the heat insulating material.

Since the shape of the heat shield plate 17 and its support mechanism are extremely simple, it can withstand the temperature history that the heat shield plate 17 undergoes and is less likely to crack.

Since the heat shield plate 17 has a small side surface area and is surrounded by a heat insulating material, the problem of heat absorption spalling on the side surfaces of the heat shield plate 17 does not occur.

Embodiment FIG. 1 shows a hearth equipped with a heat shield of this invention.

The hearth 6 is, for example, a columnar object with a rectangular cross section. This upper end surface is a mounting surface 8 on which a heated material 7 made of steel is placed. The hearth 9 is provided with an opening 10 . A hearth 6 is set in this opening 10 so as to protrude upward. As shown in FIGS. 2 and 3, this hearth 6 is made of a water-cooled steel pipe covered with castable refractories or the like.

As shown in FIG. 1, the hearth 6 is located at points A, B,
You can move in the order of C and D.

The mounting surface 8 rises from point A to point B,
Point B is reached by placing the heated material 7 supported on a support (not shown). Next, the mounting surface 8 moves forward from point B to point C with the material to be heated 7 placed on it and conveys it.

Next, the mounting surface 8 descends from point C to point D. At this time, the material to be heated 7 is supported by a support (not shown) and separated from the mounting surface 8.

Next, the mounting surface 8 retreats from point D to point A, and rises from point A to point B again. Then, the next heated material 7 is placed on the mounting surface 8 and the same operation is repeated to sequentially feed the heated material 7.

Metal fittings 1 are attached to the sides 12 and 13 of the hearth 6.
5 is fixed.

Since this fixture 15 and each element attached to the fixture 15 have the same structure on the left and right sides of the hearth 6, the left side portion will be representatively explained with reference to FIGS. 2 and 3.

The fixture 15 has a substantially U-shaped cross section and has an edge 16 formed therein.

A heat shielding plate 17 is fitted into this fixture 15 . The heat shielding plate 17 is made of ceramics, as shown in FIG. 3, and has a thin, flat plate shape with arc-shaped ends and no ribs. As the ceramic, for example, SiC, SiC-Si ₃ N ₄ , cordierite, etc. can be used.

In any case, the ceramics used are preferably those with high heat resistance strength and spalling resistance.

The heat shielding plate 17 has a thick portion 18 . This thick portion 18 has a shape that corresponds to the fixture 15. Grooves 18a are provided at two locations in the thick portion 18.

The heat shielding plate 17 has its thick portion 18 attached to the mounting tool 15.
It is attached by fitting it from the side. As shown in FIG. 2, the thick portion 18 is fixed to the fixture 15 by a ceramic sheet 15a and ceramic pins 20, 21. pins 20, 21
is fitted into the groove 18a. In this way, the heat shield plate 17 is attached to the hearth 6 so as to protrude from the side thereof.

The heat shield plate 17 is surrounded by heat insulating materials 22 and 23. The heat insulating materials 22 and 23 may be, for example, fiber blankets.

Slits 28 and 29 are provided from the center to the side edges of the heat shielding plate 17 as necessary. The slits 28 and 29 are provided to minimize uneven heat within the heat shield plate and prevent cracking due to thermal stress, and are extremely effective in preventing cracking, but there is no particular problem even if they are not provided.

As shown in FIG.
Insulating materials 30 and 31 are attached on top of 5. Both of the heat insulating materials 30 and 31 are made of wet type fiber castable or the like. The upper surface of the heat insulating material 30 is coated with a ceramic composite material 30a having extremely high heat resistance.

Note that the lower surface of the fixture 15 is covered with a plate-shaped heat insulating material 32.
covered with. This heat insulating material 32 can be made of fiber paper or the like.

The fixture 15, the heat shield plate 17, and each heat insulating material having such a structure can always cover the opening 10 even if the hearth 6 moves as described above.

Further, the heat shielding plate 17 has a simple shape and a simple supporting structure, and the heat insulating materials 22, 23,
Since the heat shield plate 17 is surrounded by the heat shield plates 30, 31, and 32, uneven heat will not be generated in the heat shield plate 17 even if there is the repeated temperature history described above, and there is no risk of cracking. Since the heat shield plate 17 has a small side surface area and is surrounded by the heat insulating materials 22, 23, 30, 31, and 32, even if the temperature changes are large, heat absorption spalling is small and it is difficult to break.

By the way, in the unlikely event that you replace the heat shield plate 17,
Each of the heat insulating materials 22, 23, 30 and the heat shielding plate 17 can be destroyed and easily removed at the same time. That is, the heat shielding plate 17 is made of ceramic, is thin, and has a flat plate shape, so that it can be broken relatively easily.

Note that even if the thick portion 18 of the heat shield plate 17 remains on the fixture 15 side after destruction, it can be easily removed from the fixture 15 by removing the pins 20 and 21. The heat shielding plate 17 can be protected from oxidation by being made of SiC, SiC-Si ₃ N ₄ based or cordierite based oxide ceramic.

FIG. 4 shows another example of this invention. In this example, the fixture 15 is provided with rectangular grooves 40, 41. The heat shield plate 17 is fitted into the fixture 15 from the side. Then, the two fixing members 43 are fitted into the grooves 40 and 41, respectively, and the lower end of the fixing member 43 is fitted into the groove 18c. In this way, the fixture 15 and the heat shield plate 17 can be integrated.

By the way, the heat shield plate does not have to be integrated, but may be divided into two parts, for example.

Effects of the invention As is clear from the above explanation, uneven heat generation does not occur even in high-temperature ranges, resulting in a long service life, and even if it becomes necessary to replace the insulation material and heat shielding plate, the insulation material and heat shielding plate can be destroyed at once. Since it can be easily removed and replaced, its maintenance becomes easy.

According to the present invention, unlike conventional ceramic heat shield plates, the structure itself can be made very easy to manufacture, and the area of the side surfaces can be reduced, as well as being arcuate with no stress concentration parts. This makes it possible to improve spalling resistance. In other words, the present invention makes it possible to obtain a heat shield plate that is easy to manufacture and has excellent spalling resistance.

In addition, in the present invention, the thickness of the heat shield plate is set to 15 to 30 mm.
By making it into a thin flat plate shape with a thickness of mm, it is possible to make it easy to install, especially to remove. By limiting the thickness of the heat shield plate to a small thickness, it is possible to remove it by destruction.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the hearth to which the heat shield plate of this invention is attached, Fig. 2 is a sectional view showing the main parts of this invention, Fig. 3 is a plan view showing the main parts of this invention, and Fig. 4
The figure is a perspective view showing another example, Figure 5 is a diagram showing a conventional hearth, Figure 6 is a diagram showing the movement of the hearth, and Figure 7 is a diagram showing the temperature (heat) history of the hearth and its vicinity. This is a graph showing. 6... Hearth, 7... Heated material, 15... Fittings, 17... Heat shielding plate, 22, 23, 30, 3
1,32...Insulation material.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a ceramic heat shield plate that is set in the opening of a walking beam heating furnace and is attached to the side of the hearth through which heated materials are transferred,
A heat shielding plate for a hearth opening of a walking beam heating furnace, characterized in that it is a thin flat plate with an arc-shaped end and a thickness of 15 to 30 mm, and is further surrounded by a heat insulating material to prevent uneven heat. (2) A heat shielding plate for a hearth opening of a walking beam heating furnace according to claim 1 of the utility model registration, in which a slit is formed.