JPH079044B2 - Strip cooling device in continuous annealing furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a strip cooling device in a continuous annealing furnace capable of making a contact angle of a strip in contact with a cooling roll 180 degrees or more.

[Prior Art] In a strip cooling device in which a plurality of strips are wound around a cooling roll arranged in a horizontal direction or a vertical direction to perform cooling, when a cooling load is large as shown in FIG. A strip 24 is wound around a large number of cooling rolls 23 arranged between the rolls 21 and 22 for cooling. When the cooling load is small, a part of the cooling rolls 23a is retracted so that the strips 24 do not come into contact with each other, or the contact angle (θ) of the rolls is changed, as shown in FIG. 3 (b). . However, when cooled in this way, between the adjacent cooling rolls 23,
Since the strip 24 is not in contact with the cooling roll 23, the cooling rate decreases during this period, and it takes time to cool to a predetermined temperature as compared with the case where continuous cooling is possible.

FIG. 4 is a graph comparing the temperature history of the strip when the strip 24 is cooled by the strip cooling device and the temperature history when the strip is continuously cooled at the same cooling rate in the cooling roll 23. The strip cooling device is a case where five cooling rolls 23 are used. However, since there is a time (t) during which the strip is not cooled between the cooling rolls 23, the strip cooling device has a time T compared to the case where continuous cooling is possible. It takes a long time to cool to a predetermined temperature.

[Problems to be Solved by the Invention] Therefore, in order to shorten the strip cooling time, the strip contact angle with the cooling roll (θ in FIG. 3).
However, the contact angle can only be adjusted by simply moving the cooling roll up and down, so the contact angle can be up to 180 degrees. There was a problem that I could only do it.

The present invention solves the above-mentioned problems of the prior art,
Since the contact angle can be 180 degrees or more, the cooling efficiency per cooling roll is large, and if the roll diameter is increased, it can be continuously cooled from the start of cooling to the end of cooling. Strip cooling in a continuous annealing furnace. The purpose is to provide a device.

[Means for Solving the Problems] A strip cooling device in a continuous annealing furnace according to the present invention includes a cooling roll, a strip wound around the cooling roll integrally with the cooling roll, and a center of the rotating shaft serving as the cooling roll. A strip cooling device in a continuous annealing furnace, comprising a moving roll configured to be movable on a concentric locus and having a roll diameter smaller than that of the cooling roll, and deflector rolls arranged before and after the cooling roll.

[Operation] In the strip cooling device in the continuous annealing furnace according to the present invention, the cooling roll and the strip are wound around the cooling roll integrally with the cooling roll, and the center of the rotating shaft moves on a locus concentric with the cooling roll. The movable roll has a roll diameter smaller than that of the cooling roll, and deflector rolls arranged before and after the cooling roll. Then, by moving the moving roll on a locus concentric with the cooling roll, the contact angle of the strip with respect to the cooling roll can be changed from 0 to around 360 degrees. The cooling capacity per roll is larger than that. If the diameter of the cooling roll is increased, 1
The book can be continuously cooled with a cooling roll, and the cooling time can be greatly shortened.

[Example] A strip cooling apparatus in a continuous annealing furnace of a first example of the present invention will be described with reference to FIG. FIG. 1 is a side view of a strip cooling device according to a first embodiment of the present invention. The strip cooling device in the continuous annealing furnace according to the first embodiment of the present invention includes a cooling roll 1 and a strip 2 which is integrated with the cooling roll 1 to cool the strip 2.
Two moving rolls 3 each having a diameter smaller than that of the cooling roll, which is wound around the rotating shaft and is configured to be movable on a locus of a concentric circle with the cooling roll 1, and deflectors arranged before and after the cooling roll 1. It is composed of rolls 4 and 5. Then, the contact angle θ of the strip 2 with the cooling roll 1 is obtained by moving the moving roll 3 on a locus of a concentric circle with the cooling roll 1.
As shown in FIG. 1 (a), θ can be changed from around 360 degrees to 0 as shown in FIG. 1 (b), so that the cooling capacity per roll is lower than that of the conventional cooling roll. By increasing the diameter of the cooling roll, it is possible to continuously cool with one cooling roll from the start of cooling to the end of cooling, and the cooling time can be greatly shortened.

FIG. 2 is a side view of the strip cooling device according to the second embodiment of the present invention. In the case of this example, one strip 12 is wound around the cooling roll 11 integrally with the cooling roll 11, and the center of the rotating shaft is movable along a locus of a concentric circle with the cooling roll 11. In this case, the arrangement of the deflector rolls 14 and 15 before and after the cooling roll 11 is also different from that in the first embodiment. Even in the case of the second embodiment, the contact angle θ is 18
Since it can be set to 0 degrees or more, the cooling capacity per cooling roll can be increased.

Next, the contact angle θ of the cooling roll and the radius B of the cooling roll
The method of determining will be described. The heat transfer rate per unit time is Q (Kcal / h), the temperature of the cooling roll and the temperature of the strip (° C) are respectively tr and ts, the contact area (m ² ) of the strip to the cooling roll is S, the heat transfer coefficient (Kcal / m ² · h ·
C)) is α, Q = α (ts-tr) S (1) The radius (m) of the cooling roll is R, the width (m) of the strip is W, and the contact angle (degree) of the strip to the cooling roll is ) Is θ, S = 2πRWθ / 360 (2) Therefore, Q = α (ts-tr) · 2πRWθ / 360 (3) On the other hand, if the strip line speed (m / min) is v, Cooling rate per unit area of q (Kcal / m
² ) is q = Q / 60vW = α (ts-tr) ・ πRθ / 10800v (4) Strip plate thickness (mm) is t, Steel specific heat (Kcal / kg ・ ° C) is c, Strip cooling If the subsequent temperature is ts ₀ , the required cooling amount per unit area of the strip q ₀
(Kcal / m ² ) is q ₀ = 7.85tc (ts−ts ₀ ) ... (5) Therefore, from equations (4) and (5), q = q ₀ ,
It is possible to obtain R and θ of the cooling roll in the case of continuously cooling with one cooling roll.

That is, α (ts−tr) · πRθ / 10800v = 7.85tc (ts−ts ₀ ) Rθ = 10800 × 7.85tcv (ts−ts ₀ ) / α (ts−tr) · π2.7 × 10 ⁴ tcv (ts −ts ₀ ) / α (ts−tr) (6) In the formula (6), the specific heat c of steel and the heat transfer coefficient α are constant, and the temperature difference between the temperature of the strip before cooling and the temperature of the cooling roll is Assuming that (ts−tr) is constant, Rθ is proportional to the product of the strip thickness t, the line speed v, and the temperature difference before and after cooling the strip (ts−ts ₀ ).

In the present invention, since only one cooling roll having a large diameter is required as the cooling roll, the amount of deformation of the strip is large because the cooling roll has a small diameter as in the conventional case, and the strip 2 as shown in FIG. Since the phenomenon that the end portion 2a floats does not occur, uneven strip cooling in the plate width direction does not occur.

[Advantages of the Invention] According to the present invention, the cooling rate of the strip can be increased.

[Brief description of drawings]

FIG. 1 is a side view of a strip cooling device according to a first embodiment of the present invention, and FIG. 2 is a side view of a strip cooling device according to a second embodiment of the present invention. FIG. 4 is a side view of a conventional strip cooling device, FIG. 4 is a graph showing a temperature history when the strip is cooled by the conventional strip cooling device, and FIG. 5 is a sectional view showing the rising of the strip. is there. 1,11 …… Cooling roll, 3,13 …… Movement roll, 4,5,14,15
…… Deflector roll.

Claims (1)

[Claims] 1. A cooling roll, and a strip wound around the cooling roll integrally with the cooling roll, wherein the center of the rotating shaft is movable on a locus of a concentric circle with the cooling roll. Also a small moving roll,
A strip cooling device in a continuous annealing furnace, comprising a deflector roll arranged before and after the cooling roll.