JPH0368935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for cooling metal strips.

Generally, a metal strip or the like delivered from a continuous annealing line can be rapidly cooled at a predetermined cooling rate by surface contact with the cooling rolls in a cooling zone consisting of a plurality of cooling roll groups. Here, the temperature difference between the metal strip and the cooling roll is
If the temperature exceeds 200 to 250 degrees, non-uniform thermal distortion occurs inside the strip, deteriorating its shape. This tendency is particularly noticeable when the strip thickness is 0.8 mm or less, so it is necessary to control the surface temperature of the cooling roll that allows the strip to be cooled, depending on the strip temperature, thickness, line speed, etc. .

By the way, a conventional cooling roll has a linear or spiral coolant flow path formed inside the roll, and allows a cooling medium such as water, oil, or molten salt to flow through the coolant flow path. Therefore, in such a cooling roll, the cooling medium flows through a predetermined flow path and the heat conduction area is constant, so by controlling the discharge temperature after the cooling medium absorbs heat, It is necessary to control its cooling capacity. However, when controlling the cooling capacity, the cooling rate can only be changed within a very narrow cooling range within the cooling capacity of the heat exchanger. Other cooling control methods include controlling cooling by changing the contact area between the strip and the roll, and changing the contact time with the roll even if the contact area between the strip and the roll is constant, i.e., changing the threading speed. Methods are known to control cooling by varying the cooling, but these also have various constraints on the production line or operation, and are often not easily implemented during sheet threading, resulting in poor cooling response, There were problems with cooling controllability over a wide range, etc.

The present invention has been made in view of the above-mentioned conventional problems, and provides a method and device for cooling a metal strip that allows the cooling capacity of a cooling roll to be controlled over a wide range without relying on temperature control of the cooling medium. The purpose is to

In order to achieve the above object, the first aspect of the present invention is to
In a method for cooling a metal strip, in which a cooling medium is flowed inside a cooling roll and the strip is cooled by contacting the cooling roll, the inner surface of the cooling roll is divided into adiabatic parts and non-insulating parts alternately in the circumferential direction, The contact area of the cooling medium with the non-insulated portion is increased or decreased to adjust the amount of heat flowing through the cooling roll from the strip side to the cooling medium side. The second aspect of the present invention is a cooling device for a metal strip that cools the strip by bringing the strip into contact with a cooling roll through which a cooling medium flows, in which a plurality of heat insulators are inserted at approximately equal locations in the circumferential direction of the inner surface. A cylindrical cooling roll, and a plurality of heat insulating bodies that are freely installed in the cooling roll so as to be relatively rotatable and can face the heat insulating body that is immersed in the inner surface of the cooling roll, are approximately equally distributed in the circumferential direction, An adjustment roll formed with a refrigerant flow path that allows a cooling medium to flow between the adjacent heat insulators, and the cooling roll and the adjustment roll can be rotated synchronously, and the cooling roll and the adjustment roll can be rotated asynchronously. and a driving means that can change the degree of overlap between the non-immersed part of the cooling roll and the coolant flow path, so that the amount of heat flowing through from the strip side to the coolant side of the cooling roll can be adjusted. This is how it was done.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view schematically showing an apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view showing the internal structure of a cooling roll according to the embodiment, and FIG. FIG.
The figures are sectional views showing different operating states of the main parts shown in Fig. 3, Fig. 5 is a drive system diagram showing the drive means according to the same embodiment, and Fig. 6 is a -
FIG. 7 is a diagram showing specific experimental results based on the same example.

The cooling roll 11 shown in FIG. 1 includes a cylindrical roll body 12 and a roll body 1 as shown in FIG.
It is rotatably supported by a bearing 14 via the shaft support 13. The outer surface of the roll body 12 can be contacted by the strip 1. Further, as shown in FIG. 3, a plurality of heat insulators 15 made of ceramic or the like are inserted into the inner surface of the roll body 12 at substantially equal positions in the circumferential direction. Of the inner surface of the roll body 12, a portion in which the heat insulator 15 is recessed forms a heat insulating portion, and a portion in which the heat insulator is not recessed forms a non-heat insulating portion.

An adjustment roll 21 is housed inside the cooling roll 11 so as to be relatively rotatable. Adjustment roll 21
The roll body 22 of the roll body 12 of the cooling roll 11 is loosely mounted, and the shaft support 1 of the cooling roll 11 is
3, and a pivot support 23 rotatably supported in a hollow portion 13A provided in the main body 3. As shown in FIG. 3, a plurality of heat insulators 2 made of ceramic or the like are provided on the outer surface of the roll body 22 of the adjustment roll 21.
4 are fixed at substantially equal locations in the circumferential direction, and a coolant flow path is formed between adjacent heat insulators 24 to allow a coolant to flow therethrough. Here, cooling roll 1
1 and the adjustment roll 2
The number of heat insulators 24 fixed to the heat insulators 1 is the same and the width is the same in the circumferential direction. Further, in the shaft support 23 of the adjustment roll 21, a refrigerant introduction hole 2 is provided that allows a cooling medium to be introduced into the cooling roll 11 from the outside.
6A, and a refrigerant discharge hole 2 that allows the cooling medium to be discharged from inside the cooling roll 11 to the outside.
6B is provided. That is, the coolant at a constant temperature is press-fitted into the coolant introduction hole 26A, flows through the coolant flow path 25 within the cooling roll 11, and is discharged to the outside from the coolant discharge hole 26B. Here, the coolant flowing through the coolant flow path 25 is cooled by contact with the non-insulated portion formed on the inner surface of the chill roll 11.
The heat passing through the strip 1 that is in contact with the outer surface of the strip 1 is removed, and the strip 1 can be rapidly cooled.

Further, the cooling roll 11 and the adjustment roll 21 can be rotated synchronously by a main motor 31 and a main reduction gear 32 including a planetary gear mechanism. In addition, the cooling roll 11 and the adjustment roll 21 include a phase adjustment electric motor 33 and a phase adjustment reduction gear 3.
4 and the main speed reducer 32 allow asynchronous rotation, and the degree of overlap between the non-insulated portion of the cooling roll 11 and the coolant flow path 25 can be adjusted. That is, the cooling roll 11 and the adjustment roll 21 are
As a result of the above-mentioned asynchronous rotation, it is possible to set the phase state in any one of the mutually non-overlapping position shown in FIG. 3, the mutually overlapping position shown in FIG. 4, or an intermediate position thereof. In the state shown in FIG. 3, the degree of overlap between the non-insulated portion of the cooling roll 11 and the coolant flow path 25 is zero, and the cooling capacity of the cooling roll 11, that is, the amount of heat flowing through from the strip side to the coolant side is minimized. The state shown in FIG. 4 assumes that the degree of overlap between the non-insulated portion of the cooling roll 11 and the coolant flow path 25 is 100%, and the cooling capacity of the cooling roll 11, that is, the flow through from the strip side to the coolant side. It maximizes the amount of heat. Therefore, while the strip 1 is being cooled by the cooling roll 11, the adjusting roll 21 is rotated asynchronously with respect to the cooling roll 11,
After adjusting the cooling capacity of the cooling roll 11 within the range of the above-mentioned minimum cooling capacity and maximum cooling capacity, if the adjusting roll 21 is rotated again in synchronization with the cooling roll 11, the cooling roll 11 is set to the desired cooling capacity. This makes it possible to rapidly cool the strip 1 stably. In addition, when the adjustment roll 21 is continuously rotated asynchronously with respect to the cooling roll 11,
Under the condition where the degree of overlap between the non-insulated portion of the cooling roll 11 and the refrigerant flow path 25 is equivalent to 50%, the refrigerant stirring effect is added, so the cooling capacity state is higher than that under the condition where the degree of overlap is 50%. It becomes possible to obtain. That is, in the present invention, the cooling capacity state is any one of a cooling capacity state in which the degree of overlap is fixed at zero, 100%, an intermediate percentage between zero and 100%, and a cooling capacity state obtained under continuous asynchronous rotation. It is possible to set

Here, the adjustable range of the cooling capacity of the cooling roll 11 in the above embodiment will be illustrated. first,
Cooling roll 1 when cooling roll 11 and adjustment roll 21 are held under the condition shown in FIG.
The minimum cooling capacity of 1 is as follows. That is, for example, when water is used as the cooling medium, the heat transfer coefficient α ₁ based on the experiment between the strip 1 and the cooling roll 11 is
is 3000Kcal/m ² h℃, and the heat transfer coefficient α ₂ based on the experiment between the cooling roll 11 and the cooling medium is 2000Kcal/m ²
h℃, heat transfer coefficient of cooling roll 11 (steel) λ ₁
35Kcal/mh℃, thermal conductivity (ceramic) λ ₂ of heat insulator 15 is 1.0Kcal/mh℃, cooling roll 11
The thickness of the back side of the insulation body immersed part Δx ₁ is 19.58×10 ^-3
m, and the thickness Δx ₂ of the heat insulator 15 is 1.42×10 ^-3 m, the minimum cooling capacity of the cooling roll 11, that is, the average heat transmission coefficient α _MIN is α _MIN = 1/1/α ₁ +1/ α ₂ +Δx ₁ /λ ₁ +Δx ₂ /λ
₂ = 350 [Kcal/m ² h℃] ...(1). In addition, the cooling roll 11 and the adjustment roll 21
The maximum cooling capacity of the cooling roll 11 when the cooling roll 11 is maintained under the condition shown in FIG. 4 is as follows. In other words, the thermal conductivity α ₁ based on the experiment between the strip 1 and the cooling roll 11 is set to 3000Kcal/
m ² h°C, the thermal conductivity α ₂ based on the experiment between the cooling roll 11 and the cooling medium is 2000 Kcal/m ² h°C, the thermal conductivity (copper) λ ₁ of the cooling roll 11 is 35 Kcal/mh°C,
Thickness Δx of non-insulated part of cooling roll 11 (Δx ₁ +Δx ₂ )
is 21×10 ^-3 m, the maximum cooling capacity of the cooling roll 11, that is, the average heat transmission coefficient α _MAX is α _MIN = 1/1/α ₁ + 1/α ₂ + Δx/λ ₁ = 700 [Kcal /m ² h℃] …(2).

Next, the specific structure of the drive means consisting of the main motor 31, the main reducer 32, the phase adjustment motor 33, and the phase adjustment reduction gear 34 in the above embodiment will be explained with reference to FIGS. 5 and 6. . A gear 35 is fixed to the output shaft of the main motor 31, the gear 35 meshes with a gear 37 fixed to the main shaft 36, and a sprocket 38 fixed to the main shaft 36 is connected to one side of the cooling roll 11 via a chain 39. The sprocket 40 is connected to the sprocket 40 which is fixed to the shaft support 13. Further, an internal gear 42 rotatably supported by the main shaft 36 is disposed outside the small gear 41 fixed to the main shaft 36, and a planetary gear 43 meshes with both the small gear 41 and the internal gear 42. , a sprocket 44 coaxially fixed to an internal gear 42 is connected to a sprocket 46 via a chain 45, a gear 47 is coaxially fixed to the sprocket 46, and is fixed to one shaft support 23 of the adjustment roll 21. A gear 47 is meshed with the gear 48 shown in FIG. Furthermore, the planetary gear 43 is pivotally supported at the rotating end of an arm 49 that rotates coaxially with the main shaft 36, and a gear 50 is fixed to the rotational center of the arm 49. A gear 50 is meshed with a gear 51 fixed to the output shaft.

That is, the cooling roll 11 is driven by the main electric motor 31 to rotate the gears 35 and 37 and the sprocket 3.
8. Through the chain 39 and sprocket 40,
It is possible to rotate at the same speed as the conveyance speed of the strip 1. Further, the adjustment roll 21 is driven by the main electric motor 31 to move the gears 35 and 37 and the small gear 4.
1. It can rotate at a synchronous speed with the cooling roll 11 via a planetary gear 43, an internal gear 42, a sprocket 44, a chain 45, a sprocket 46, and gears 47 and 48, which do not revolve but only rotate. Furthermore, by driving the phase adjustment electric motor 33, the arm 49 is rotated via the phase adjustment reduction gear 34 and the gears 51, 50, and the rotation speed ratio of the small gear 41 and the internal gear 42 is changed to the diameter ratio D of both. ₄₂ /D ₄₁ , and allows the adjustment roll 21 to rotate asynchronously in the advance direction or the retardation direction with respect to the cooling roll 11. That is, the cooling roll 11 and the adjustment roll 21 are rotated asynchronously by the drive of the phase adjustment motor 33, so that the phase of both can be adjusted, and then by stopping the phase adjustment motor 33, both can be adjusted. Synchronous rotation is possible under the condition that the new phase is maintained.

Next, specific experimental results based on the above example will be explained with reference to FIG. In this experiment, the plate thickness was 0.8 mm, the plate speed was 100 m/min, and the contact angle between the strip and the first cooling roll, second cooling roll, and third cooling roll (cooling roll 11) was 152.3°, respectively. 161.4° and 152.3°, the initial temperature of the plate was 700°C, and the temperature of the cooling medium was 50°C.The cooling capacity of the cooling roll was adjusted to three levels, and the cooling rate of the strip was measured under these conditions. be. First, the degree of overlap between the non-insulated portion of the cooling roll 11 and the coolant flow path 25 is set to zero, and the cooling capacity of the cooling roll 11 is set to the minimum value α _MIN
(350Kcal/m ² h℃), the cooling rate of the strip is relatively slow, as shown by the broken line, and the temperature of the strip is approximately equal to its initial temperature.
The temperature reached 550°C in about 4 seconds from 700°C. Next, when the degree of overlap between the non-insulated part of the cooling roll 11 and the refrigerant flow path 25 is set to 100%, and the maximum value α _MAX (700 Kcal/m ² h°C) of the cooling capacity of the cooling roll 11 is set, As shown by the solid line, the plate temperature becomes relatively steep, and the plate temperature rises approximately 4 seconds after the initial temperature of 700℃.
The temperature reached 400℃. Next, when the degree of overlap between the non-insulated part of the cooling roll 11 and the refrigerant flow path 25 is set to 50%, an intermediate gradient is shown as shown by the dashed line, and the plate temperature is set to the initial temperature of 700°C. Approximately 4 seconds after
The temperature reached 450℃. Also, when the cooling roll 11 and the adjustment roll 21 are operated asynchronously, the degree of overlap is 50.
The results are almost the same as in the case of %, and as the relative rotational speed between the cooling roll 11 and the adjustment roll 21 is increased, the cooling speed becomes even higher.

Note that the cooling medium is not limited to the water used in this embodiment, but may be applied to the cooling control of the present invention using, for example, oil, or even molten salt when a slow cooling rate is desired.

As described above, the method and apparatus for cooling a metal strip according to the present invention has the effect that the cooling capacity of the cooling roll can be controlled over a wide range without depending on the temperature control of the cooling medium.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing an apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view showing the internal structure of a cooling roll according to the same embodiment, and FIG.
4 is a sectional view showing different operating states of the main part shown in FIG. 3, FIG. 5 is a drive system diagram showing the drive means according to the same embodiment, and FIG. 6 is a sectional view of the main part along the line. FIG. 5 is a view taken along the - line in FIG. 5, and FIG. 7 is a diagram showing specific experimental results based on the same example. 1... Strip, 11... Cooling roll, 15
... Insulator, 21 ... Adjustment roll, 24 ... Insulator, 25 ... Refrigerant flow path, 31 ... Main motor, 32
...Main reduction gear, 33...Phase adjustment electric motor.

Claims (1)

[Claims] 1. A method for cooling a metal strip in which a cooling medium is flowed inside a cooling roll and the strip is brought into contact with the cooling roll to be cooled. A method for cooling a metal strip, characterized in that the contact area of the cooling medium with the non-insulated portion is increased or decreased, and the amount of heat passing through from the strip side to the cooling medium side of the cooling roll is adjusted. 2. In a metal strip cooling device that cools the strip by bringing the strip into contact with a cooling roll through which a cooling medium flows, a cylindrical cooling roll with a plurality of heat insulators inserted at approximately equal locations in the circumferential direction of the inner surface, A plurality of heat insulating bodies are freely installed in the roll so as to be relatively rotatable and can face the heat insulating body immersed in the inner surface of the cooling roll, and are approximately evenly distributed in the circumferential direction, and cooling is carried out between adjacent heat insulating bodies. An adjustment roll formed with a refrigerant flow path that allows a medium to flow, and a cooling roll and an adjustment roll that can be rotated synchronously,
a driving means that rotates the cooling roll and the adjusting roll asynchronously to change the degree of overlap between the non-insulating part of the cooling roll and the refrigerant flow path;
A cooling device for a metal strip, characterized in that the amount of heat flowing through from the strip side to the cooling medium side in a cooling roll can be adjusted.