JPH07331335A - Device for adjusting roll crown rate in heating furnace - Google Patents

Abstract

PURPOSE:To always execute the optimum control of roll crown and to prevent the lowering of heat efficiency by executing the cooling the end parts of the roll corresponding to the variation of a metal strip width in a continuous heat treatment furnace. CONSTITUTION:This device for adjusting the roll crown rate in the heating furnace for continuously executing the heat treatment while carrying the metal strip through plural rolls formed in the furnace by cooling both end parts of the roll is provided with a radiating cooling plate 3 movable in the width direction of the roll faced to the roll. In the device, the radiating cooling plate 3 is divided into plural plates in the width direction of the roll faced to the roll and each divided radiating cooling plate can independently change the cooling capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for adjusting the amount of roll crown of furnace rolls in a continuous heat treatment furnace.

[0002]

2. Description of the Related Art In a continuous heat treatment furnace, the temperature of a steel strip rises from a room temperature to a recrystallization temperature of 600 to 900 ° C. or higher and the ambient temperature of a roll is a heating device between rolls installed in the upper and lower portions according to the traveling direction of the strip. Due to the influence of
It varies between ℃ and +800 ℃. The temperature of the roll around the strip is almost the same as the temperature of the strip due to the high contact heat transfer coefficient between the strip and the roll. The temperature is close to the surroundings. Therefore, a temperature gradient is generated in the roll axial direction, and the roll is thermally deformed based on the temperature gradient. In order to prevent troubles due to meandering and buckling of the steel strip in the furnace, the roll has a predetermined crown under operating conditions,
An initial crown more than offsetting the thermal deformation is applied. However, the steel strip processing temperature is changed based on the product quality of the steel strip, and the size of the steel strip is also changed, so that the furnace temperature and the strip passing position of the steel strip are also changed. For this reason, since the ambient temperature of the roll also changes, it is difficult to constantly maintain a crown that does not cause troubles due to meandering and buckling.

In order to cope with such a problem, the following apparatus has been disclosed as an apparatus for adjusting the roll crown amount of the furnace roll in the continuous heat treatment furnace.

The technique disclosed in Japanese Examined Patent Publication No. 57-23733 discloses a cooling device in which a front end is closed and a coolant passage is formed inside, facing a non-contact portion of a furnace roll with a steel strip. The apparatus is characterized in that it is arranged separately from the roll, and the non-contact portion is cooled by a cooling medium flowing through the flow path.

Further, Japanese Patent Laid-Open No. 62-253734,
And the technology described in "Iron and Steel Vol.78 (1992) T145-148", the temperature difference along the axial direction of the roll is supported by blowing a gas onto the part of the roll supporting the strip that is not in contact with the strip. The apparatus is characterized in that it is provided with a gas blowing means for reducing

Further, conventionally, a shielding plate is installed between the rolls so that the difference between the ambient temperature around the rolls and the steel strip temperature does not become large, whereby radiation from the heating device between the rolls to the furnace wall around the rolls and the rolls is performed. Is being prevented. However, in order to avoid contact with the steel strip, the above-mentioned shield needs to be spaced at intervals of 50 to 150 mm. Therefore, high-temperature gas on the heating device side flows into the roll chamber, and a sufficient effect cannot be obtained. As a measure for improving the sealing property as described above, JP-A-2-28243 has been proposed.
Japanese Patent No. 1 discloses a nozzle that secures a sealing property by forming strip-shaped gas jets on the front and back surfaces of a steel strip in a slit-shaped steel strip passage portion.

[0007]

However, the above-mentioned prior art has the following problems. Japanese Patent Publication 57-2
The cooling tube system of the technique described in Japanese Patent No. 3733 has a small cooling wall area and a small roll crown control effect. Such indirect (radiative) cooling has a lower heat transfer coefficient than direct (gas jet) cooling, and when a cooling wall is installed at the lower part of the roll, the cooling wall area sufficient to adjust the roll crown is sufficient for contact with the strip. You have to take it as large as possible while avoiding. In addition, if the number of tubes is increased, the number of penetration points between the furnace wall and the movable tube will be increased, which will be complicated and the equipment cost will be increased.

The technique described in Japanese Patent Laid-Open No. 62-253734 and "Iron and Steel Vol.78 (1992) T145-148" has a high heat transfer coefficient and a large cooling effect, but the cooling gas is a furnace. When mixed with the atmosphere, the temperature of the furnace lowers and the thermal efficiency of the furnace lowers.

On the other hand, in the furnace roll of the heating section, a temperature gradient is generated in the axial direction of the roll from about 200 mm inside the width end of the steel strip (hereinafter simply referred to as steel strip end) to about 150 mm outside, and The thermal deformation in the radial direction is as much as 20 to 60% of the difference in the amount of deformation between the roll end and the roll center. The roll temperature distribution in the roll axial direction and the deformation amount in the radial direction at the end of the steel strip are the same regardless of the width of the steel strip. In addition, it is common to change the strip width between 600 and 1300 mm in the same equipment.
Since the maximum height is about 900 to 1900 mm, the position of the steel strip edge changes by 350 to 500 mm. Therefore, it is necessary to change the cooling width of the roll end depending on the width of the steel strip or to determine the cooling width according to the minimum width, and the cooling width should be minimized to avoid lowering the thermal efficiency of the heating equipment. However, the above-mentioned conventional technology cannot meet such a demand.

In addition, the nozzle for forming the strip-shaped gas jets on the front and back surfaces of the steel strip in the slit-shaped steel strip passage portion for improving the sealing property of the shielding plate to secure the sealing property needs to pressurize a large amount of gas. Therefore, the power cost increases.

According to the present invention, by cooling the roll end corresponding to such a variation of the steel strip width, the roll crown is always optimally controlled, and the sealing property of the heat shield plate is improved. The purpose is to prevent a decrease in thermal efficiency.

[0012]

The above-mentioned problems can be solved by the following means. A device for adjusting a crown amount of a roll of a heating furnace for continuously performing heat treatment while conveying a metal strip through a plurality of rolls provided in a furnace by cooling both ends of the roll, An in-furnace roll crown adjusting device for a heating furnace, which has a radiation cooling plate which faces the roll and is movable in the roll width direction.

A device for adjusting the crown amount of a roll of a heating furnace that continuously heat-treats while conveying a metal strip through a plurality of rolls provided in the furnace by cooling both ends of the roll. Facing the roll,
The heating furnace is characterized by having a plurality of radiant cooling plates divided in the roll width direction, and each of the divided radiative cooling plates is capable of changing its cooling capacity independently. In-furnace roll crown adjustment device.

A device for adjusting the crown amount of a roll of a heating furnace for continuously performing heat treatment while transporting a metal strip through a plurality of rolls provided in the furnace by cooling both ends of the roll. And a shielding device that shields the roll and the radiant cooling plate from the metal band heating device.

A device for adjusting the crown amount of a roll of a heating furnace that continuously heat-treats while transporting a metal strip through a plurality of rolls provided in the furnace by cooling both ends of the roll. A shield plate that shields the roll and the radiative cooling plate from the metal strip heating device, leaving the passage opening of the metal strip, and a seal roll that blocks the flow of gas is provided in the passage opening of the metal strip. An apparatus for adjusting the amount of roll crown in a furnace of a heating furnace according to the above item 1 or 2.

[0016] The roll crown amount adjusting device for a heating furnace according to any one of items 1 to 3, wherein the roll is made of a material having a small linear expansion coefficient.

[0017]

The function of the present invention will be described. Regarding the cooling capacity of the device of the present invention, the required dimensions of the radiation cooling plate facing the roll and the radiation wall temperature were examined by heat conduction analysis and thermal deformation analysis by the finite element method.

As a calculation example, the steel strip temperature (300 ° C.) and roll ambient temperature (700 ° C.) in the first half of the radiant tube type heating furnace
4 shows the result of simulating the thermal crown in the case where the present invention is not used for the roll having a large difference in
5A to 5C, FIG. 4 is a diagram showing the temperature distribution, and FIG. 5 is a diagram showing the displacement in the radial direction. 4 to 5 show that the temperature difference and the displacement difference (1.2 mm) between the end of the steel strip and the end of the roll not in contact with the steel strip are large.

In order to prevent the trouble of the steel strip due to the thermal crown, it is desirable that the thermal crown does not change regardless of the steel strip temperature, the ambient temperature and the steel strip width, and the difference in the steel strip temperature and the ambient temperature between the rolls is the largest. Under these conditions, the roll surface temperature distribution should be made almost flat. From this point of view, in order to avoid the radiation from the furnace and to make the radiation radiation from the radiation cooling plate sufficiently effective, the roll surface should be close to 70 mm or less and the surface angle 80
A radiant cooling plate of about 100 degrees is required, and if a radiant cooling plate is provided on the lower surface of the roll in order to mainly cool the roll without adversely affecting the heating of the steel strip, it is necessary to obtain this surface angle of 80 to 100 degrees. When the roll diameter is 650 to 900 mm, the circumferential length depends on the face angle, but the projected dimension in the roll radial direction is
(Roll diameter) It became clear that it was necessary to set it to -30 to -150 mm. If it is smaller than -30 mm, it may come into contact with the steel strip, and if it is larger than -150 mm, the cooling capacity is reduced.

On the other hand, in the in-furnace roll of the heating section, a temperature gradient is generated in the roll axial direction from about 200 mm inside the steel strip end to about 150 mm outside the steel strip, and the radial thermal deformation at the steel strip end is caused by the roll end and the roll. 20-60% of the difference in the amount of deformation in the center
It also becomes. Therefore, since cooling of the steel strip end portion is insufficient by cooling only the outside of the steel strip end, it is necessary to change the cooling width in accordance with the steel strip width. , Or the radiation cooling plate is divided into multiple parts in the roll width direction and the cooling width is changed by changing the cooling capacity independently of each other, so that the required roll cooling can be obtained and the roll crown can be adjusted appropriately. To be done.

FIGS. 6 to 7 show the lower surface of the roll 100, which is 200 mm inward from the end of the steel strip to the outer roll end, according to the present invention.
Is the result of radiative cooling of the range of degrees with a 120 ° C cooling wall,
FIG. 6 is a diagram showing the temperature distribution, and FIG. 7 is a diagram showing the displacement in the radial direction. 6 to 7, it can be seen that the roll surface temperature distribution becomes almost flat and the thermal crown can be suppressed to about 0.4 mm.

FIGS. 4 to 7 show the case of the austenitic stainless steel such as HH and HK of ACI standard which is often used as a roll material, which is determined by the heat resistance and the creep strength. If the cooling device according to the present invention is used, the roll ambient temperature can be set to 600 ° C. or less in the low temperature region in the first half of the furnace, so that 13Cr (11 to 14% Cr) steel or the like having a small linear expansion coefficient can be used. FIGS. 8 to 9 show the results of the case where such a 13Cr steel roll is used, without radiative cooling. FIG. 8 shows the temperature distribution and FIG. 9 shows the radial displacement. . 10 to 11 show the results of radiative cooling when using a roll of 13Cr steel.
Shows a temperature distribution, and FIG. 11 shows a radial displacement.

Table 1 summarizes the thermal deformation amounts of the above rolls.

[0024]

[Table 1]

FIGS. 12 to 13 show the results of radiative cooling when a 13Cr steel roll was used, and the results of radiative cooling wall range of 60 degrees, and FIG. 12 shows the temperature distribution. 13 and 14 are diagrams showing displacement in the radial direction. From the figure,
In the case of 13Cr steel, even if the range of the radiant cooling wall is reduced to 60 degrees, the effect is sufficient, and it can be seen that the specifications of the cooling equipment can be reduced.

The shielding device of the present invention enhances the cooling effect by the shielding effect. Further, the seal roll in the present invention covers the gap between the shielding plate and the steel strip so that the inflow of atmospheric gas from the heating device side to the roll chamber is reduced, thereby stabilizing the atmospheric temperature in the roll chamber, The adverse effect on the deformation is prevented.

[0027]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment according to the movable system of the present invention, which is an example in which the structure is installed on both ends of the roll. In addition to this, an example in which the structure is installed below both ends of the roll can be considered. In FIG. 1, 1 is a refrigerant inlet, 2 is a refrigerant outlet, 3 is a radiation cooling plate, 4 is a roll axial moving shaft, 5 is an expansion joint, 6 is a roll axial driving device, and 7 is a roll axial driving device.
Is a roll body, and 8 is a furnace wall. In this embodiment, the radiation cooling plate 3 is provided in an arc shape along the roll body 7. The space between the radiation cooling plate 3 and the roll body 7 is 5 to 70 mm. Five
If it is less than 70 mm, it may come in contact with the roll, and if it is more than 70 mm, the cooling capacity will decrease. A partition wall is provided inside the radiant cooling plate 3 so that the wall temperature of the radiant cooling plate 3 is within 150 ° C. to secure the flow velocity of the refrigerant. The roll axis direction moving shaft 4 penetrates the furnace wall 8 and moves the radiation cooling plate 3 in the roll axis direction by the roll axis direction driving device 6 outside the furnace. An expansion joint 5 is attached to the furnace wall penetrating portion of the roll axis direction moving shaft 4 which also serves as the pipe to prevent the gas in the furnace from leaking to the outside of the furnace. The amount of movement of the radiant cooling plate 3 in the roll axis direction is such that the end of the radiative cooling plate 3 on the furnace center side is movable from 0 to 200 mm from the end of the steel strip having the minimum width to the furnace center side. The width of the radiation cooling plate 3 in the roll axial direction is the length up to the roll body end (shoulder) at the above position.

Here, when the steel strip is changed from the narrow material to the wide material, the radiant cooling plate is moved to the roll end side before the width is changed, and conversely when the wide material is changed to the narrow material. Is
It is better to prevent the steel strip from being drawn by moving it to the center of the roll after changing the width.

Further, when the steel strip is changed from the narrow material to the wide material, the radiation cooling plate is moved to the roll end side after the width is changed, and conversely, when the wide material is changed to the narrow material, It is better to prevent the steel strip from meandering by moving it to the center of the roll.
The above-described change timing is used properly by setting a certain value of W / t (steel strip width / steel strip thickness) representing the buckling rigidity of the steel strip as a threshold value.

FIG. 14 shows an embodiment of the control system of the radiation cooling plate according to the movable system of the present invention. In the following figures, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.
The edge of the radiant cooling plate is inside the width of the strip with respect to the width of the steel strip.
The position of the radiation cooling plate in the roll axis direction is controlled so that it becomes 0 mm. In the case of Tin-CAL (steel strip width 600 to 1070 mm), if the steel strip width is 700 mm or less, it is fixed at the position of 600 mm.
In the case of Sheet-CAL (steel strip width 900 to 1880 mm), if the steel strip width is 1000 mm or less, it is fixed at the position of 900 mm.

FIG. 2 shows an embodiment according to the dividing system of the present invention, which is an example of a structure installed on the upper ends of both ends of the roll. In addition to this, an example in which the structure is installed below both ends of the roll can be considered. In FIG. 2, 9 is a partition wall, 10 is a divided cooling plate, 11 is a refrigerant supply pipe, 1
Reference numeral 2 is a refrigerant return pipe. The inside of the radiation cooling plate 3 is divided into a plurality of parts by a partition wall 9. A refrigerant supply pipe 11 and a return pipe 12 are provided in each of the divided cooling plates 10, and the refrigerant is supplied by a valve provided on the inlet side of the refrigerant supply pipe 11.
A stop is performed and the cooling width is changed according to the width of the steel strip.

FIG. 15 shows an embodiment of the control system of the radiation cooling plate according to the division method of the present invention. 15, parts that are the same as those shown in FIG. 2 are given the same reference numerals, and descriptions thereof will be omitted. And the steel strip width W, the relationship between the inner width Y _n of the _{channel, (W-Y n) /} 2 ≧ 0~100mm and so as, by controlling the shut-off valve, changing over the channel.

FIG. 3 is a view showing an embodiment of the heat shield device and the seal roll in the present invention. In FIG.
13 is a shield plate, 14 is a seal roll, 15 is a transport roll, 16 is a steel strip, 17 is a heating device, and 18 is a shield plate between the transport rolls. The shield plate 13 is provided with a heating device 17 provided between a plurality of transfer rolls 15 installed in the upper and lower parts of the furnace.
The space between the carrier roll 15 and the carrier roll 15 is shielded. Alternatively, the shielding range may be variable in the roll axial direction according to the movement of the roll cooling device. Further, the shield plate 18 between the transfer rolls is effective for maintaining the furnace temperature around the transfer rolls, and the upper part of the furnace is usually installed at the upper part of the transfer rolls for every 1 to 3 rolls, but it is also installed at the bottom part of the furnace. And more effective.

FIG. 3B is a detailed view of the seal roll portion. Two seal rolls 14 are installed close to each other with a steel strip sandwiched in a slit-shaped steel strip passage portion. It rotates in synchronization with. Since there is no slip with the steel strip 16,
The distance from the steel strip can be 30 mm or less. The seal roll is a light roll and may be strip contact rotation, but synchronous rotation is preferable.

Further, as shown in FIG. 3 (C), one roll is pressed against the steel strip 16 to a position where the buckling of the steel strip 16 is prevented, and one sealing roll 14 is brought close to the steel strip 16 in the same manner. You may rotate it. Thereby, the out-of-plane deformation of the steel strip and the compressive stress in the width direction of the steel strip can be reduced, and the drawing of the steel strip can be prevented.

With the seal roll of the present invention, the amount of gas flowing from the heating device side into the roll chamber is reduced, and the temperature rise in the roll chamber can be reduced. Further, by adjusting the amount of atmospheric gas fed into the roll chamber so that the pressure inside the roll chamber becomes higher than the pressure on the side of the heating device, the amount of gas flowing into the roll chamber can be further reduced.

In addition to the method for adjusting the roll crown of the first to fourth inventions, a fluid is caused to flow inside the roll, the temperature of the roll at the end of the roll is measured, and the metal strip in contact with the roll is measured. The temperature of the roll is obtained by measurement or calculation, and the temperature of the roll at the end of the roll and the temperature difference between the metal strip in contact with the roll are within a predetermined range. This is possible as an example. FIG. 16 shows such an embodiment. 16, the same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 16, 23 is a heat medium flow path, 24 is a heat medium thermometer, 25 is a heat medium temperature controller, 2
6 is a flow control valve, 27 is a pump or blower, 28 is a radiation thermometer, and 29 is a heat exchanger. In FIG. 16, arrows indicate the direction in which the heat medium flows. The temperature of the steel strip 16 and the end of the in-furnace roll 15 is measured by the radiation thermometer 28, and the temperature of the heating medium on the exit side of the in-furnace roll is measured by the heat medium thermometer 24. Based on these temperatures, the heat medium temperature adjusting device 25 is used so that the difference between the temperature of the steel strip 16 and the temperature of the end of the furnace roll 15 falls within a predetermined range (preferably within 30 ° C.). The flow control valve 26 is adjusted to adjust After passing through the heat medium thermometer 24, the heat medium exiting the in-furnace roll 15 is divided into a flow passage that passes through the heat exchanger 29 and a flow passage that does not pass through, and the amount of each is adjusted by the flow control valve 26. . The respective flow paths merge again, and when the heat medium is a fluid, it is sent to the inlet side of the in-furnace roll 15 by a pump (a blower when the heat medium is a gas) 27. In this way, the heat medium circulates and passes through the inside of the furnace roll 15 at the optimum temperature, so that the temperature distribution of the furnace roll can be maintained substantially uniform.

Further, in the method of adjusting the crown of the roll shown in FIG. 16, it is possible to use the technique of forming the roll with a material having a small linear expansion coefficient.

Although the above embodiments have been described in detail for the case of steel strips, they are applicable to all metal strips.

[0040]

As described above, according to the present invention, by cooling the roll end portion corresponding to the variation of the metal strip width, it becomes possible to always control the optimum roll crown, and the meandering of the metal strip and Trouble due to buckling can be prevented. In addition, the sealing roll has an effect of improving the sealing property of the shielding plate and preventing a decrease in thermal efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment according to a movable system of the present invention.

FIG. 2 is a diagram showing an embodiment according to a division method of the present invention.

FIG. 3 is a diagram showing an embodiment of a heat shield device and a seal roll according to the present invention.

FIG. 4 is a diagram showing a temperature distribution when the present invention is not used.

FIG. 5 is a diagram showing displacement in the radial direction when the present invention is not used.

FIG. 6 is a diagram showing a temperature distribution when radiative cooling is used.

FIG. 7 is a diagram showing displacement in the radial direction when radiative cooling is used.

FIG. 8 is a diagram showing a temperature distribution when a 13Cr steel roll is used.

FIG. 9 is a diagram showing radial displacement when a 13Cr steel roll is used.

FIG. 10 is a view showing a temperature distribution when radiative cooling is used for a 13Cr steel roll.

FIG. 11 is a diagram showing displacement in the radial direction when radiative cooling is used with a 13Cr steel roll.

FIG. 12: The range of the cooling wall for radiative cooling is 60 with a 13Cr steel roll.
The figure which showed the temperature distribution when it was set to the degree.

FIG. 13: The range of the cooling wall for radiative cooling is 60 with a 13Cr steel roll.
The figure which showed the displacement of the radial direction at the time of degrees.

FIG. 14 is a diagram showing an embodiment of a control system of a radiation cooling plate according to the movable system of the present invention.

FIG. 15 is a diagram showing an embodiment of a control system of a radiant cooling plate according to the division method of the present invention.

FIG. 16 is a diagram showing an example in which a fluid is caused to flow inside the transfer roll to adjust the roll crown.

[Explanation of Codes] 3 Radiant Cooling Plate 4 Roll Axial Movement Axis 7 Roll Body 13 Shielding Plate 14 Seal Roll

Claims (5)

[Claims] 1. A device for adjusting a crown amount of a roll of a heating furnace for continuously performing heat treatment while transporting a metal strip through a plurality of rolls provided in the furnace by cooling both ends of the roll. An apparatus for adjusting the amount of roll crown in a furnace of a heating furnace, comprising a radiation cooling plate which faces the roll and is movable in the roll width direction. 2. An apparatus for adjusting a crown amount of a roll of a heating furnace for continuously performing heat treatment while transporting a metal strip through a plurality of rolls provided in the furnace by cooling both ends of the roll. The radiant cooling plate divided into a plurality in the roll width direction facing the roll, each radiant cooling plate divided, it is possible to independently change the cooling capacity. An apparatus for adjusting the amount of roll crown in a furnace of a heating furnace. 3. An apparatus for adjusting the crown amount of a roll of a heating furnace for continuously performing heat treatment while transporting a metal strip through a plurality of rolls provided in the furnace by cooling both ends of the roll. A roll crown amount in the heating furnace according to claim 1 or 2, further comprising a shield device that shields the roll and the radiant cooling plate from a metal band heating device. Adjustment device. 4. A device for adjusting a crown amount of a roll of a heating furnace for continuously performing heat treatment while conveying a metal strip through a plurality of rolls provided in the furnace by cooling both ends of the roll. Is, leaving the passage opening of the metal strip, a roll and the shielding plate for shielding the radiation cooling plate from the metal strip heating device is provided, the passage opening of the metal strip,
The in-furnace roll crown amount adjusting device for a heating furnace according to claim 1 or 2, further comprising a seal roll that prevents gas flow. 5. The in-furnace roll crown amount adjusting device for a heating furnace according to claim 1, wherein the roll is made of a material having a small linear expansion coefficient.