JPH0619120B2 - Method for preventing thermal deformation of strip support roll - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for preventing thermal deformation of a strip plate support roll around which a strip plate to be heat-treated is wound to change the passage direction thereof.

<Prior Art> A vertical furnace such as a continuous annealing furnace for steel plates incorporates a belt support roller such as a hearth roll and a bottom roll around which a belt is wound to change the passage direction.

For example, as shown in FIG. 3 showing an example of a conventional hearth roll used in a continuous annealing furnace, a roll 2 is rotatably supported in the furnace 1, and a predetermined amount is provided while traveling in the furnace 1. The strip plate 3 to which the heat treatment of 1 is applied is wound around a roll 2 that changes the passing direction of the strip plate 3.

Here, when the strip plate 3 is heat-treated, the inside of the furnace 1 needs to be heated by some heating device. In such a case, the strip plate temperature is usually lower than the furnace temperature. is there. Further, the roll 2 is rotated together with the passage of the strip plate 3, and the central strip contact portion A with which the strip 3 can come into contact with the roll 2
The strip plate non-contact portion B at the side end which is not in contact with the strip plate 3 is formed along the longitudinal direction of the roll 2. Therefore, the strip non-contact portion B is heated by the ambient temperature of the furnace 1 over the entire circumference thereof, but the portion of the strip contact portion A which the strip 3 contacts is cooled by the strip 3. The Rukoto. As a result, the temperature of the strip contact portion A becomes lower than that of the strip non-contact portion B, and the roll 2 is thermally deformed as shown by the solid line from the state of the broken line showing the contour shape of the roll 2 before thermal deformation in the figure. Will cause.

As described above, when the roll 2 is thermally deformed, the passage of the strip plate 3 is hindered. Therefore, conventionally, when the roll 2 is provided with an initial crown, for example, when the strip plate 3 is heated as described above, The strip contact portion A is formed into a barrel-shaped contour having a larger diameter than the strip non-contact portion B so as to form a regular cylindrical shape when 2 is thermally deformed.

<Problems to be Solved by the Invention> The initial crown formed on the roll may or may not be appropriate depending on the operating condition of the furnace, and determines how much initial crown is attached to the roll. It is quite difficult.

When the initial crown is attached too large to the roll, as shown in FIG. 4 showing the state at this time, the roll 2
Even after thermal deformation, the diameter of the center part was too large,
Tensile stress is applied to both ends of the strip 3 in contact with the roll 2 in the width direction, whereas compressive stress is applied to both ends of the strip 3 in the width direction immediately before and immediately after contact with the roll 2 by its reaction. . When the strip 3 buckles due to this compressive stress, a bulge 4 is generated in the central portion, and the bulge 4 is narrowed down on the roll 2 to form a wrinkle 5. This is a drawback that a so-called heat buckle is introduced and the product becomes defective.

On the other hand, if the initial crown of the roll is too small,
As shown in FIG. 5 showing the state at this time, since the central portion of the roll 2 is dented, the strip plate 3 meanders toward one of the longitudinal directions of the roll 2, and as a result, in an extreme case, The plate 3 may come into sliding contact with the partition wall to make it difficult to operate, or the band plate 3 may break.

Therefore, it is considered that the roll is separated from the heat treatment furnace so as to remove the influence of the radiant heat in the furnace, but in any case, the strip plate passage for leading out the strip plate from the heat treatment furnace is rolled from the heat treatment furnace. Since the gas must be formed in the partition wall for partitioning the rolls, and the gas in the heat treatment furnace reaches the periphery of the roll through this strip passage, the roll cannot be deformed due to heat.

The present invention has been made in view of various problems associated with thermal deformation of a conventional strip support roll used in such a heat treatment furnace, and an object thereof is to provide a method capable of preventing thermal deformation of the strip support roll. It prevents the generation of heat buckle and meandering of the plate.

<Means for Solving Problems> A method of preventing thermal deformation of a strip plate supporting roll according to the present invention is a heat treatment furnace for heat treating a strip plate, and the heat treatment furnace through a groove-shaped strip plate passage formed in a partition wall. A roll chamber communicating with the strip chamber, and a strip plate support roll rotatably accommodated in the roll chamber and wound around the strip plate in the heat treatment furnace via the strip plate passage to change the passage direction of the strip plate. The heat treatment of the strip plate is performed while the gas having a temperature substantially equal to the temperature of the strip plate is blown into the roll chamber.

<Operation> When a gas having a temperature substantially equal to the temperature of the strip is blown into the roll chamber separated from the heat treatment furnace, this gas flows out to the heat treatment furnace through the strip passage. The temperature in the roll chamber corresponds to the temperature of the strip plate, and the temperature distribution along the longitudinal direction of the roll is made uniform.

<Example> As shown in FIG. 1 showing a sectional structure of a part of a heat treatment furnace capable of realizing the method of the present invention and FIG. 2 showing a sectional shape taken along the line II-II thereof, as shown in FIG. A support roll 14 is rotatably supported in a roll chamber 13 partitioned by 12, and is guided into the roll chamber 13 through a pair of groove-shaped strip plate passages 15 formed in the partition wall 12. The strip 16 is wound around the support roll 14 and the sheet passing direction is reversed in this embodiment.

The inside of the heat treatment furnace 11 and the inside of the roll chamber 13 are in communication with each other through a communication pipe 17, and in the middle of this communication pipe 17, a feeding fan 18 for feeding the gas in the heat treatment furnace 11 to the roll chamber 13 side, A damper 19 that controls the flow rate of gas flowing through the communication pipe 17 and a heat exchanger 20 that exchanges heat between the atmosphere and the gas from the heat treatment furnace 11 are incorporated in series. Further, a bypass pipe 21 is interposed in parallel with the damper 19 and the heat exchanger 20 in the communication pipe 17, and a throttle 22 is incorporated in the middle of the bypass pipe 21. This diaphragm 22 is a damper 1
9 is for compensating the pressure loss of the gas in the communication pipe 17 due to the heat exchanger 20 and the heat exchanger 20. It is also possible to replace the throttle 22 with a damper and omit the damper 19 provided in the middle of the communication pipe 17. Is.

Therefore, the opening of the damper 19 is adjusted so that the temperature of the gas flowing into the roll chamber 13 is substantially equal to the temperature of the strip plate 16, and the temperature distribution along the longitudinal direction of the support roll 14 is made uniform. .

In the case where the roll chamber 13 is simply provided, when the temperature difference between the strip plate 16 and the atmosphere in the heat treatment furnace 11 is 500 degrees to 700 degrees (in units of Celsius, the same applies hereinafter), a continuous annealing furnace is taken as an example. The temperature difference between the part that can contact the strip plate 16 of 14 and the part that does not contact the strip plate 16 is 250 to 400 degrees.
However, according to the present invention, when the gas controlled at ± 50 ° with respect to the temperature of the strip 16 is blown into the roll chamber 13 at a rate of 300 cubic meters per hour, the above-mentioned temperature difference is from 50 ° to 1 °.
I was able to fit in the range of 50 degrees.

<Effects of the Invention> According to the method of the present invention, the temperature distribution of the strip plate supporting roll can be made uniform in the longitudinal direction thereof, so that thermal deformation of the roll is prevented and heat buckle or meandering does not occur. It is possible to improve the yield.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a main part of an embodiment of a heat treatment furnace capable of realizing the method of the present invention, and FIG. 2 is a sectional view taken along the line II-II of FIG.
3 to 5 are conceptual diagrams showing the shape of the strip plate supporting roll in the conventional heat treatment furnace. In the figure, reference numeral 11 is a heat treatment furnace, 12 is a partition wall, 13 is a roll chamber, 14 is a support roll, 15 is a strip plate passage, 16 is a strip plate, 17 is a communicating pipe, 18 is a feed fan, and 19 is A damper, 20 is a heat exchanger, 21 is a bypass pipe, and 22 is a throttle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhisa Nakajima 1 Kawasaki-cho, Chiba-shi, Chiba Inside the Kawasaki Steel Co., Ltd. (72) Inventor Akira Kishida 1 Kawasaki-cho, Chiba-shi Chiba Steel Co., Ltd. In-house

Claims (1)

[Claims] 1. A heat treatment furnace for heat treating a strip, a roll chamber communicating with the heat treatment furnace through a groove-shaped strip passage formed in a partition wall, and a roll chamber rotatably accommodated in the roll chamber. A strip plate supporting roll that wraps the strip plate in the heat treatment furnace through a plate passage to change the passage direction of the strip plate, and a gas having a temperature substantially equal to the temperature of the strip plate in the roll chamber. A method for preventing thermal deformation of a strip supporting roll, characterized in that the strip is heat-treated while being blown.