JPH09256075A - Uniform heating device for continuous heat treatment furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly execute heat treatment to the whole surface of a steel strip and to reduce the meandering and the heat buckle of the steel strip by parallel arranging plural radiant tubes in the width direction of the steel strip and controlling the temp. distribution in the width direction of the steel strip in continuous heat treatment furnace. SOLUTION: Plural pieces of the radiant tubes 14 for heating the steel strip 12 are arranged in the upper and lower surfaces of radiant tube fitting part 13 in a uniform heating device A in the contiguous heat treatment furnace. The radiant tube 14 is formed in a cylindrical shape and arranged with its longitudinal direction matched with the carrying direction of the steel strip 212 and also parallel with the steel strip 12. Further, plural radiant tubes 14 are parallel arranged in the width direction of the steel strip 12 like a raft state and the calorific valve of the heat source can independently be adjusted for each source by changing the load of each heat source. Atmospheric gas of N2 gas, etc., is filled up in the inner part of the fiancee body 11 and the steel strip 12 is heated with the radiation heat from the radiant tubes 14. Thermal crown of the hearth roll can be adjusted by controlling the temp. distraction in the axial direction of the roll with he radiant tubes 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a uniform heating apparatus for a continuous heat treatment furnace which continuously conveys a steel strip and performs heat treatment such as annealing and surface treatment. More specifically, the present invention relates to a steel strip using a radiant tube. The present invention relates to a uniform heating device for a continuous heat treatment furnace that can uniformly heat the steel sheet, adjust the thermal crown of the hearth roll, and reduce the occurrence of meandering of the steel strip and heat buckle.

[0002]

2. Description of the Related Art In recent years, in continuous heat treatment equipment for continuously heat-treating steel strip, a radiant tube that indirectly heats by radiant heat using a burner, a heater or the like as a heat source is often used because of the necessity of preventing the oxidation of the steel strip. Has been done. In the heat treatment of steel strips, the thickness of the steel strip is extremely thin and the thickness is strictly controlled, so if the temperature distribution of the heating element is not uniform, the temperature distribution in the steel strip will be uneven. Occurs and the heat treatment of the steel strip is not performed uniformly, resulting in deterioration of quality. Further, the temperature distribution of the hearth roll arranged in the furnace body changes depending on the contact state with the steel strip, and due to this temperature fluctuation, a difference in thermal expansion occurs in the axial direction of the hearth roll, and the surface shape of the hearth roll is delicately changed. fluctuate. Therefore, the thermal crown of the hearth roll fluctuates in the roll axial direction (or simply referred to as the axial direction), and the fluctuation causes the meandering during the transportation of the steel strip, or the generation of wrinkles due to the fluctuation of the local stress applied to the steel strip ( This causes problems such as so-called heat buckles.

Various developments have been made in order to improve these points. For example, in Japanese Unexamined Patent Publication No. 2-4927, a plurality of nozzles are arranged so as to surround the base of a radiant tube, and a plurality of nozzles are arranged. No. 2 discloses a method for heating a steel strip in which atmospheric gas is blown onto a locally high temperature portion of a radiant tube to cool it and the temperature distribution in the longitudinal direction of the radiant tube is uniformly heated. In addition, Japanese Unexamined Patent Publication
JP-A-67123 discloses that in order to prevent meandering and heat buckle of a steel strip by partitioning a portion where a hearth roll of a continuous heat treatment furnace is arranged with a partition wall or a heat shield plate, the temperature inside the room is a center portion of the hearth roll. A method for preventing the meandering of steel strip and the heat buckle by controlling the room temperature so as to approach the temperature is disclosed.

[0004]

However, the conventional method for heating a steel strip and the method for preventing the meandering of the steel strip and the heat buckle still have the following problems to be solved. That is, in JP-A-2-4927, the temperature distribution in the longitudinal direction of the radiant tube itself can be made uniform by using the nozzle at the base, but due to the difference in radiant heat from the furnace wall and the like. The amount of heat received (or the amount of heat input) differs between the central portion and both end portions of the steel strip, so that there is a problem that the conveyed steel strip cannot be uniformly heated. On the other hand, in Japanese Patent Application Laid-Open No. 62-67123, the temperature difference between the central portion and the edge portion of the hearth roll is slightly improved, but since only the heat shield plate is arranged, the precision of the hearth roll in the roll axial direction is improved. Temperature control is difficult,
There is a problem that the fluctuation of the thermal crown in the roll axis direction cannot be completely controlled. Further, since the heat shield plate is arranged to be isolated from the heating chamber and the furnace temperature in this roll chamber is set lower than that in the heating chamber, there is a problem that it is difficult to raise the temperature of the steel strip in this portion.

The present invention has been made in view of the above circumstances, and it is possible to uniformly heat a steel strip and perform a uniform heat treatment over the entire surface of the steel strip. Further, a thermal crown of a hearth roll is used. It is an object of the present invention to provide a uniform heating device of a continuous heat treatment furnace that can control and reduce the meandering and heat buckle of a steel strip and can efficiently heat the steel strip.

[0006]

According to the present invention, there is provided a semiconductor device comprising:
The uniform heating device of the continuous heat treatment furnace described is a uniform heating device of a continuous heat treatment furnace provided with a radiant tube for heating the steel strip by radiant heat, wherein the radiant tubes are arranged in parallel in the width direction of the steel strip, The temperature distribution in the width direction of the steel strip can be controlled. The uniform heating device for a continuous heat treatment furnace according to claim 2, wherein in the uniform heating device for a continuous heat treatment furnace according to claim 1, the radiant tube is arranged apart from the upper surface and / or the lower surface of the steel strip for a predetermined period. , While aligning the longitudinal direction of the radiant tube with the conveying direction of the steel strip, a plurality of the radiant tubes are juxtaposed in the widthwise direction of the steel strip so that the temperature distribution in the widthwise direction of the steel strip can be controlled. There is. A uniform heating device for a continuous heat treatment furnace according to claim 3 is the uniform heating device for a continuous heat treatment furnace according to claim 1, wherein the radiant tube is formed in a hanging type and is separated from the hearth roll by a predetermined distance. A plurality of the hearth rolls are arranged side by side in the roll axis direction so that the temperature distribution in the roll axis direction of the hearth roll can be controlled. Here, as the radiant tube, a burner, an electric heater or the like is used as a heat source. Alternatively, only air may be blown.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to the attached drawings, an embodiment in which the present invention is embodied will be described to provide an understanding of the present invention. 1 is a front sectional view of a main part of a uniform heating apparatus for a continuous heat treatment furnace according to the first embodiment of the present invention, and FIG. 3 (a) is a graph showing the distribution of the load of the radiant tube in the width direction of the steel strip when the load of the radiant tube is uniform, and FIG. 3 (b) is a graph of the steel strip when the load of the radiant tube is uniform. FIG. 4A is a graph showing the distribution of the temperature of the steel strip in the width direction, and FIG. 4A is a graph showing the distribution of the load of the radiant tube in the width direction of the steel strip when the load of the radiant tube is changed.
(B) is a graph which shows the temperature distribution of the steel strip in the width direction of the steel strip when the load of the radiant tube is changed.

The uniform heating apparatus A of the continuous heat treatment furnace according to the first embodiment of the present invention is a steel strip 1 having a single pass.
2 heat treatment furnace. In FIGS. 1 and 2, a steel strip 12 for heat treatment in a cylindrical furnace body 11 is continuously conveyed in the direction of arrow B, and a radiant tube having a cross-sectional area larger than that of the furnace body 11 at a predetermined portion of the furnace body 11. The mounting portions 13 are arranged at predetermined intervals. On the upper and lower surfaces of the radiant tube mounting portion 13, a plurality of radiant tubes 14 that radiate heat from the surface and heat the steel strip 12 are arranged. The radiant tube 14 is formed in a cylindrical shape, and the longitudinal direction thereof is aligned with the conveying direction of the steel strip 12 and is arranged parallel to the steel strip 12. Further, a plurality of radiant tubes 14 are arranged in a raft shape in the width direction of the steel strip 12, and the heat generation amount can be independently adjusted for each one by changing the load of each heat source. .

Next, a method of using the uniform heating apparatus A of the continuous heat treatment furnace having the above structure will be described with reference to FIGS. The steel strip 12 is conveyed at a constant speed in the substantially central portion of the furnace body 11, and the furnace body 11 is filled with an atmospheric gas such as N ₂ gas. The steel strip 12 is heated by the radiant heat from the radiant tube 14. Since the radiant tubes 14 are juxtaposed in six rows in the width direction of the steel strip 12, the same thermal energy load can be applied in the width direction of the steel strip 12 as shown in FIG. Energy is uniformly radiated from the radiant tube 14 in the width direction of the steel strip 12, but the temperature distribution of the steel strip 12 is as shown in FIG.
As shown in (b), it is not uniform and the central portion is low and both edges are high. This is because the amount of heat received differs depending on the position of the steel strip 12, and the amount of heat received at both edges is greater than that at the center. In order to make the temperature distribution of the steel strip 12 uniform, it is necessary to make the load distribution of the radiant tube 14 as shown in FIG. As shown in FIG. 4 (a), by reducing the load on the radiant tubes 14 located at both edges of the steel strip 12, the heat input to the entire widthwise surface of the steel strip 12 can be made small and uniform. it can. As a result, the heat input to the steel strip 12 is balanced,
Since the amount of heat retained in the steel strip 12 is the same at each position,
The temperature of the steel strip 12 can be made uniform throughout. FIG.
(B) shows a state in which the amount of heat is balanced and the temperature distribution of the steel strip 12 is uniform.

As described above, in the uniform heating apparatus A of the continuous heat treatment furnace according to the present embodiment, the radiant tube 14 is arranged so as to be separated from the upper surface of the steel strip 12 for a predetermined period, and the radiant tube 14 is arranged in the longitudinal direction. The steel strip 1 is made to match the conveying direction of the steel strip 12, and the radiant tube 14 can control the temperature distribution in the width direction of the steel strip 12.
Since two or more pieces are arranged side by side in the width direction of 2, the heat input amount of the steel strip 12 can be balanced and the temperature distribution of the steel strip 12 can be made uniform, so that high-quality and highly reliable heat treatment is performed. be able to. Further, even when the steel strips 12 having different thicknesses and widths are heat-treated, the temperature distribution and the radiant heat of the radiant tube 14 can be freely adjusted to a temperature state suitable for the steel strips 12 to be heat-treated, and thus various types and various types can be used. Steel strip 12
Can be heat-treated stably and with high reliability.

Next, a uniform heating apparatus C for a continuous heat treatment furnace according to a second embodiment of the present invention will be described with reference to the drawings. Here, FIG. 5A is a cross-sectional view of a main part of a uniform heating apparatus for a continuous heat treatment furnace according to the prior art, and FIG. 5B is a uniform heating apparatus for a continuous heat treatment furnace according to a second embodiment of the present invention. FIG. 6 is a plan view of a main part side of FIG. 5 (b), FIG. 7 (a) is a side view of a main part of a hearth roll of a uniform heating device of a conventional continuous heat treatment furnace, and FIG. 8) is a graph showing the surface temperature distribution of the hearth roll in the roll axis direction, FIG.
FIG. 8A is a side view of a main portion of a hearth roll of a uniform heating apparatus for a continuous heat treatment furnace according to a second embodiment of the present invention, FIG.
(B) is a graph showing a surface temperature distribution in the roll axial direction.

The uniform heating apparatus C for the continuous heat treatment furnace according to the second embodiment of the present invention is a vertical furnace having a plurality of passes. 5 (b) and 6, a hearth roll 15 for supporting the steel strip 12 on the upper and lower parts of the box-shaped furnace body 11a.
(The lower hearth roll 15 is not shown) are arranged at a predetermined interval, the steel strip 12 is continuously stretched over the upper and lower hearth rolls 15, and is vertically bellows-shaped in the furnace body 11a. Have been transported to. Adjacent Hearth Roll 15
Six radiant tubes 16 suspended from the ceiling of the furnace body 11a are arranged side by side in the gap between them in the roll axis direction of the hearth roll 15. In addition, on the contact surface of the radiant tube 16 with the ceiling of the furnace body 11a, the furnace body 11 is
A sealing material 17 for sealing a and preventing leakage of atmospheric gas is attached. The radiant tube 16 is formed in a U shape, and fuel and air are supplied from one end and exhausted from the other end. During that time, the wall surface of the radiant tube 16 is heated and radiant heat is radiated from the wall surface of the radiant tube 16. The central bent portion of the radiant tube 16 is located inside the hearth roll 15, and the side surface of the hearth roll 15 is arranged so as to face the radiant tube 16. The furnace body 11a is divided into a hearth roll installation portion (or roll chamber) 19 and a heating chamber 20 by a heat shield plate 18, and the heating chamber 20 has a radiant tube 2 therein.
1 is arranged.

Next, a method of using the uniform heating apparatus C of the continuous heat treatment furnace having the above structure will be described with reference to FIGS. The steel strip 12 is stretched between the hearth rolls 15, continuously conveyed in the furnace body 11 a, and heated by the radiant heat from the radiant tube 16.

In the conventional continuous heat treatment furnace, as shown in FIG.
As shown in (b), the steel strip 12 having a low temperature comes into contact with the surface of the hearth roll 15, and the temperature of the contact surface of the hearth roll 15 with the steel strip 12 locally drops. Due to this temperature variation, a difference occurs in the amount of thermal expansion of the surface of the hearth roll 15 in the roll axis direction, and as shown in FIG.
The central part of is deformed into a concave shape. When this deformation amount is large, meandering and heat buckling of the steel strip 12 occur. Also,
In the conventional technique, as shown in FIG. 5A, a heat shield plate 18 is disposed below the hearth roll 15, the hearth roll installation portion (roll chamber) 19 and the heating chamber 20 are isolated from each other, and By setting the temperature low, the temperature difference in the axial direction of the hearth roll 15 is reduced, but since the steel strip 12 passes through the hearth roll installation portion 19 whose temperature is lower than that of the heating chamber 20, heating is efficiently performed. Can not do it.

In the uniform heating apparatus C for the continuous heat treatment furnace according to the second embodiment of the present invention, six radiant tubes 16 are arranged side by side in the roll axis direction of the hearth roll 15. Since the load amount of each radiant tube 16 can be controlled independently, the surface temperature of the radiant tube 16 can be controlled by varying in the roll axis direction of the hearth roll 15. For example, the load of the radiant tube 16 in the central portion of the hearth roll 15 is made higher than that of both edges to efficiently heat the steel strip 12, while the load of the radiant tube 16 at both edges is set to the minimum so that the heating chamber The surface temperature difference in the width direction of the hearth roll 15 is reduced by blocking the radiant heat from the heat roll 20 to the hearth roll 15 to prevent the temperature rise at both edges of the hearth roll 15, as shown in FIG.
It can be reduced as in (b). As a result, as shown in FIG. 8A, it is possible to maintain an appropriate roll crown with a constant thermal expansion amount.

As described above, in the uniform heating apparatus C for the continuous heat treatment furnace according to the present embodiment, the radiant tube 16 formed in a hanging shape is arranged at a predetermined distance from the hearth roll 15, and Hearth Roll 15
Since a plurality of hearth rolls 15 are arranged side by side in the roll axis direction so that the temperature distribution in the roll axis direction can be controlled, the temperature distribution on the surface of the hearth roll 15 can be freely controlled and the thermal crown amount can be made uniform. can do. Therefore, it is possible to reduce the meandering and heat buckle of the steel strip 12 and manufacture a high-quality heat treatment with a high yield. Further, even if the thickness or width of the steel strip 12 changes, the radiant tube 16 can be changed to a load state suitable for the state, and the thermal crown can be controlled to an optimum shape. The steel strip 12 can also be efficiently heated.

As described above, the present invention is not limited to the configurations described in the above-described embodiments, and other embodiments and modifications that can be considered within the scope of the matters described in the claims. Is included. For example, in the above-described embodiment, the case where six radiant tubes are arranged in parallel has been described, but other numbers may be used. Also,
In the second embodiment, the case where the radiant tube is suspended from the ceiling has been described, but a shelf may be provided on the side surface of the furnace body and suspended or projected upward from the shelf. Further, although the hanging type radiant tube is arranged orthogonally to the steel strip, it may be arranged in parallel. Furthermore, although the radiant tube of the heating chamber is arranged so that its longitudinal direction coincides with the width direction of the steel strip, it may be arranged so that its longitudinal direction coincides with the conveying direction of the steel strip.

[0018]

According to the uniform heating apparatus of the continuous heat treatment furnace of claims 1 to 3, in the uniform heating apparatus of the continuous heat treatment furnace provided with the radiant tube for heating the steel strip by radiant heat, the radiant tube is Since multiple temperature distributions in the width direction of the steel strip can be controlled in parallel in the width direction, the temperature distribution in the tropical zone can be adjusted freely in the width direction of the steel strip, and the temperature distribution of the steel strip itself can be accurately controlled. Therefore, the steel strip can be subjected to heat treatment with high quality and reliability. Also, by controlling the temperature distribution in the roll axis direction of the radiant tube, it is possible to adjust the thermal crown of the hearth roll, reduce the meandering of the steel strip and heat buckle due to fluctuations of the thermal crown, and improve product quality. It is possible to improve the manufacturing yield as well as the manufacturing yield. Further, since it is possible to change to a preferable temperature distribution for each operation depending on the thickness, width and material of the steel strip, it is possible to efficiently heat a wide variety of steel strips and improve equipment efficiency.

Particularly, in the uniform heating apparatus of the continuous heat treatment furnace according to claim 2, the radiant tube is arranged so as to be separated from the upper surface and / or the lower surface of the steel strip for a predetermined period, and the longitudinal direction of the radiant tube is set to the steel strip. Since the radiant tubes are aligned in the width direction of the steel strip so that the temperature distribution in the width direction of the steel strip can be controlled, the temperature distribution in the width direction of the steel strip can be precisely controlled. It is possible to correct the temperature distribution of the steel strip due to the difference in the amount of heat received between the central part and both edges of the steel strip, so that the steel strip can be heated uniformly and high quality heat treatment is possible. Is.

Further, in the uniform heating apparatus of the continuous heat treatment furnace according to the third aspect, the radiant tube is formed in a hanging type and is arranged at a predetermined distance from the hearth roll, and the hearth roll is rolled. Since a plurality of hearth rolls are arranged side by side in the axial direction so that the temperature distribution in the axial direction can be controlled, the temperature distribution on the surface of the hearth roll can be controlled freely and the shape of the thermal crown can be stabilized. It is possible to reduce meandering and heat buckling during the transportation of the strip, and it is possible to obtain a high quality steel strip.

[Brief description of drawings]

FIG. 1 is a front sectional view of essential parts of a uniform heating apparatus for a continuous heat treatment furnace according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of a main part of a uniform heating device of the continuous heat treatment furnace.

FIG. 3 (a) is a graph showing the distribution of the load of the radiant tube in the width direction of the steel strip when the load of the radiant tube is made uniform. (B) It is a graph which shows the temperature distribution of the steel strip in the width direction of the same steel strip.

FIG. 4A is a graph showing a load distribution of the radiant tube in the width direction of the steel strip when the load of the radiant tube is changed. (B) It is a graph which shows the temperature distribution of the steel strip in the width direction of the same steel strip.

FIG. 5 (a) is a cross-sectional view of essential parts of a conventional uniform heating apparatus for a continuous heat treatment furnace. (B) It is a principal part sectional view of the uniform heating apparatus of the continuous heat treatment furnace which concerns on the 2nd Embodiment of this invention.

6 is a plan view of the main part side of FIG. 5 (b).

FIG. 7 (a) is a side view of a main part of a hearth roll of a conventional uniform heating apparatus for a continuous heat treatment furnace. (B) A graph showing a surface temperature distribution in the roll axis direction of the hearth roll.

FIG. 8A is a side view of a main portion of a hearth roll of a uniform heating apparatus for a continuous heat treatment furnace according to a second embodiment of the present invention. (B) A graph showing a surface temperature distribution in the roll axis direction of the hearth roll.

[Explanation of symbols]

A uniform heating device for continuous heat treatment furnace B arrow C uniform heating device for continuous heat treatment furnace 11 furnace body 11a furnace body 12 steel strip 13 radiant tube attachment part 14 radiant tube 15 hearth roll 16 radiant tube 17 sealant 18 heat shield plate 19 roll Room (hearth roll installation part) 20 Heating room 21 Radiant tube

Claims (3)

[Claims] 1. A uniform heating apparatus for a continuous heat treatment furnace, comprising a radiant tube for heating a steel strip with radiant heat, wherein a plurality of the radiant tubes are arranged side by side in the width direction of the steel strip, A uniform heating device for a continuous heat treatment furnace, which is capable of controlling the temperature distribution. 2. The radiant tube is arranged so as to be separated from the upper surface and / or the lower surface of the steel strip for a predetermined period, and the longitudinal direction of the radiant tube is aligned with the conveying direction of the steel strip, and the radiant tube is The uniform heating device for a continuous heat treatment furnace according to claim 1, wherein a plurality of the steel strips are arranged in parallel in the width direction of the steel strip so that the temperature distribution in the width direction of the steel strip can be controlled. 3. The hearth roll is formed such that the radiant tube is formed in a hanging type and is arranged at a predetermined distance from the hearth roll, and the temperature distribution in the roll axis direction of the hearth roll can be controlled. 2. A uniform heating device for a continuous heat treatment furnace according to claim 1, wherein a plurality of the heating devices are arranged side by side in the roll axis direction.