WO2024018724A1

WO2024018724A1 - Cold rolling equipment, steel plate manufacturing equipment, cold rolling method, and steel plate manufacturing method

Info

Publication number: WO2024018724A1
Application number: PCT/JP2023/016986
Authority: WO
Inventors: 公貴日野; 正樹平井; 一郎田野口; 哲矢荒川
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2022-07-19
Filing date: 2023-04-28
Publication date: 2024-01-25
Also published as: JP2024013098A

Abstract

Provided are cold rolling equipment, steel plate manufacturing equipment, a cold rolling method, and a steel sheet manufacturing method capable of suppressing deformation of work rolls and suppressing brittle fracture during rolling. The cold rolling equipment comprises: one or more cold rolling mills that spray a coolant toward the work rolls and a metal steel strip to cold-roll the metal steel strip; a plurality of rolls that are provided farther upstream than the one or more cold rolling mills in a conveyance direction of the metal steel strip and are used to convey the metal steel strip; and a control device that controls the height difference between the plurality of rolls. The control device controls the plurality of rolls such that the metal steel strip is lowered toward the downstream side in the conveyance direction, on the upstream side of at least a portion of one or more cold rolling mills including the most upstream rolling mill provided on the most upstream side.

Description

Cold rolling equipment, steel plate manufacturing equipment, cold rolling method, and steel plate manufacturing method

The present disclosure relates to cold rolling equipment, steel sheet manufacturing equipment, cold rolling methods, and steel sheet manufacturing methods.

Steel plates containing Si, such as electrical steel plates, have low toughness and are prone to brittle fracture during rolling. Generally, the greater the amount of Si contained in a steel sheet, the lower the ductile-brittle transition temperature tends to be. As a method of preventing brittle fracture, there is a method of heating a steel plate to a temperature equal to or higher than the ductile-brittle transition temperature before rolling.

In steel plate rolling equipment, tandem mills, etc., coolant is injected towards the nip between the work roll and the steel plate in order to lubricate the steel plate during rolling and prevent thermal deformation of the work roll. Therefore, the injected coolant bounces off the work rolls and flows over the steel plate towards the entry side. When a steel plate is heated before rolling, the temperature of the steel plate decreases due to coolant flowing toward the inlet side (coolant liquid).

The length of the coolant in the longitudinal direction of the steel plate increases as the line speed decreases. Furthermore, as the line speed increases, the force of drawing in the coolant by the steel plate becomes stronger, so the liquid riding length tends to become shorter. Therefore, when the line speed is slow, even if the steel plate is preheated, the steel plate is cooled to about the temperature of the coolant.

For example, Patent Document 1 discloses a technology in which a draining device is provided to spray draining air onto the top roll of a rolling mill in order to prevent the coolant sprayed onto the top roll of a rolling mill from falling onto the strip and lowering the temperature of the strip. Disclosed.

In order to solve the lack of lubrication of the steel plate that occurs in the draining device of Patent Document 1, for example, as shown in Patent Document 2, a technique is disclosed in which a highly concentrated emulsion is supplied to the steel plate in a small amount.

On the other hand, in downstream stands such as multi-high rolling mills, the temperature of the steel sheet rises due to the heat generated during rolling, but if the temperature is too high, the amount of heat input to the work roll during rolling increases and a thermal crown is formed on the work roll. Ru. When a thermal crown is formed, the rolled shape of the steel sheet deteriorates.

In particular, as the rolling speed increases, the amount of heat input per unit time increases, the thermal crown grows further, and the rolled shape of the steel sheet deteriorates.

Japanese Patent Application Publication No. 2000-271614 JP2006-272382A

However, although providing the liquid draining device described in Patent Document 1 is effective for suppressing a decrease in plate temperature, poor lubrication of the steel plate occurs and seizure is likely to occur.

In the case of Patent Document 2, since the emulsion is supplied to the steel plate on the inlet side of the rolling mill, the steel plate is cooled by the emulsion and the temperature of the steel plate is lowered.

Here, in a downstream stand such as a multi-high rolling mill, if the temperature of the steel plate is too high due to heat generated during rolling, the temperature of the steel plate is lowered by the coolant and the amount of heat input to the work rolls can be suppressed. However, when the rolling speed is high, the liquid riding length becomes short, so the cooling effect is small.

In addition, increasing the coolant flow rate improves the cooling capacity, and increasing the liquid riding length further improves the cooling capacity. However, it is necessary to increase the number of pumps, and review the diameter of the coolant water supply piping and the size of the circulation tank.

The present disclosure has been made in view of such problems, and provides cold rolling equipment, steel plate production equipment, cold rolling method, and steel plate production that can suppress deformation of work rolls and suppress brittle cracking during rolling. The purpose is to provide a method.

(1) Cold rolling equipment according to an embodiment of the present disclosure,
one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; a plurality of rolls provided in the metal steel strip for conveying the metal steel strip, and a control device that controls the height difference of the plurality of rolls,
The control device is configured such that, on the upstream side of at least a portion of the one or more cold rolling mills including the most upstream rolling mill provided on the most upstream side, the metal steel strip is lowered toward the downstream side in the conveying direction. The plurality of rolls are controlled as follows.

(2) As an embodiment of the present disclosure, in (1),
The control device controls the steel type of the metal steel strip, the line speed, the injection flow rate of the coolant, and the flow rate of the metal steel strip on the upstream side of at least a portion of the one or more cold rolling mills including the most upstream rolling mill. An inclination angle of the metal steel strip with respect to a biting portion of the one or more cold rolling mills is set based on at least one of temperature and a target temperature of the metal steel strip.

(3) As an embodiment of the present disclosure, in (2),
The control device controls the plurality of rolls so that the inclination angle is 2° or more and 10° or less.

(4) As an embodiment of the present disclosure, in any one of (1) to (3),
The one or more cold rolling mills are plural,
The control device is configured such that, on the upstream side of at least a portion of the one or more cold rolling mills including the most downstream rolling mill provided on the most downstream side, the metal steel strip is positioned at a higher level toward the downstream side in the conveying direction. The plurality of rolls are controlled as follows.

(5) The cold rolling equipment according to an embodiment of the present disclosure includes:
one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; a plurality of rolls provided in the metal steel strip for conveying the metal steel strip, and a control device that controls the height difference of the plurality of rolls,
The control device is configured such that, on the upstream side of at least some of the one or more cold rolling mills including the most downstream rolling mill provided on the most downstream side, the metal steel strip is positioned at a higher level toward the downstream side in the conveying direction. The plurality of rolls are controlled as follows.

(6) As an embodiment of the present disclosure, in (5),
The control device controls the steel type of the metal steel strip, the line speed, the injection flow rate of the coolant, and the flow rate of the metal steel strip on the upstream side of at least a portion of the one or more cold rolling mills including the most downstream rolling mill. An inclination angle of the metal steel strip with respect to a biting portion of the one or more cold rolling mills is set based on at least one of temperature and a target temperature of the metal steel strip.

(7) As an embodiment of the present disclosure, in (6),
The control device controls the plurality of rolls so that the inclination angle is −10° or more and −2° or less.

(8) The steel plate manufacturing equipment according to an embodiment of the present disclosure includes:
The cold rolling equipment according to any one of (1) to (7) and equipment for cutting the metal steel strip are provided.

(9) The cold rolling method according to an embodiment of the present disclosure includes:
one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; A cold rolling method carried out in a cold rolling facility comprising: a plurality of rolls provided at a steel strip for transporting a metal steel strip; and a control device for controlling a height difference between the plurality of rolls.
The control device is configured such that, on the upstream side of at least some of the one or more cold rolling mills including the most upstream rolling mill provided on the most upstream side, the metal steel strip is positioned at a lower level toward the downstream side in the conveying direction. controlling the plurality of rolls in such a manner.

(10) The cold rolling method according to an embodiment of the present disclosure includes:
one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; A cold rolling method carried out in a cold rolling facility comprising: a plurality of rolls provided at a steel strip for transporting a metal steel strip; and a control device for controlling a height difference between the plurality of rolls.
The control device is configured such that, on the upstream side of at least some of the one or more cold rolling mills including the most downstream rolling mill provided on the most downstream side, the metal steel strip is positioned at a higher level toward the downstream side in the conveying direction. controlling the plurality of rolls in such a manner.

(11) A method for manufacturing a steel plate according to an embodiment of the present disclosure,
The method includes a step of performing the cold rolling method of (9) or (10) and cutting the metal steel strip.

According to the present disclosure, it is possible to provide cold rolling equipment, steel sheet manufacturing equipment, cold rolling method, and steel sheet manufacturing method that can suppress deformation of work rolls and suppress brittle cracking during rolling.

FIG. 1 is a diagram illustrating a configuration example of a cold rolling mill included in cold rolling equipment according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating a configuration example of a cold rolling mill included in cold rolling equipment according to an embodiment of the present disclosure. FIG. 3 is a diagram for explaining changes in temperature of a metal steel strip in a cold rolling facility.

Hereinafter, a cold rolling facility, a steel plate manufacturing facility, a cold rolling method, and a steel plate manufacturing method according to an embodiment of the present disclosure will be described with reference to the drawings.

First, with reference to FIG. 3, an example of temperature change of a metal steel strip in a cold rolling facility will be explained. In the example of FIG. 3, the cold rolling equipment includes a heating device, a plurality of rolls, and first to fourth cold rolling mills. The first to fourth cold rolling mills perform cold rolling of a metal steel strip that is heated by a heating device and conveyed by a plurality of rolls. The cold rolling equipment includes a heating device, a first cold rolling mill, a second cold rolling mill, a third cold rolling mill, and a third cold rolling mill from the upstream side to the downstream side in the conveying direction of the metal steel strip. 4 cold rolling mills are installed in sequence. The cold rolling equipment may constitute a part of the steel plate manufacturing equipment. The steel plate manufacturing equipment may further include equipment for cutting a metal steel strip, for example downstream of the fourth cold rolling mill, to cut out a steel plate of a desired size.

Each of the first to fourth cold rolling mills includes a coolant header (see FIG. 1) that injects coolant toward the work roll and the metal steel strip. The coolant is, for example, a liquid mixture of rolling oil and water, and is injected for the purpose of ensuring lubricity and cooling the work rolls.

When a metal steel strip is inserted into a cold rolling mill, if it is not heated to a certain level, there is a possibility of brittle fracture. Steel sheets manufactured by manufacturing equipment including cold rolling equipment include, for example, electrical steel sheets. Generally, electrical steel sheets have a ductile-brittle transition temperature of 70 to 80°C, so after being heated to a degree above the ductile-brittle transition temperature (for example, 200 to 500°C), they are inserted into rolling equipment and rolled. However, the temperature of the steel strip decreases due to rolling oil, etc. provided during rolling, and the temperature of the metal steel strip at the time of biting in the cold rolling mill (hereinafter also referred to as "plate temperature") reaches the ductile-brittle transition temperature. If it is less than that, breakage is likely to occur. In cold rolling equipment, depending on the level of rolling oil, the plate temperature could drop lower than expected.

On the other hand, if the plate temperature at the time of biting is high, breakage can be prevented, but there is also processing heat generated during rolling, and the plate temperature can become even higher in the downstream rolling pass. If the plate temperature is higher than expected, the thermal crown of the work roll will grow, potentially causing shape defects in the rolled metal steel strip.

The graph in the lower part of FIG. 3 shows the change in temperature of the metal steel strip. The vertical axis shows the temperature of the metal steel strip, and the horizontal axis shows the position in the manufacturing process corresponding to the cold rolling equipment shown in the above figure. The coolant injected in the first to fourth cold rolling mills bounces off the work rolls and flows over the metal steel strip toward the entry side (upstream side), causing coolant flooding. The length in the longitudinal direction (conveying direction) of the metal steel strip carrying the coolant becomes longer as the line speed is lower, and becomes shorter as the line speed becomes faster because the force for drawing in the coolant by the steel plate becomes stronger. In cold rolling equipment, a metal steel strip is rolled and stretched in the longitudinal direction by a rolling mill, so the line speed increases from the upstream cold rolling mill to the downstream cold rolling mill. In the example shown in Fig. 3, in the first cold rolling mill and the second cold rolling mill where the line speed is relatively slow, the length of the coolant liquid is long, and the temperature of the metal steel strip is lower than the optimum temperature (ductile-brittle). (below the transition temperature). In addition, in the fourth cold rolling mill, where the line speed is relatively high, the length of the coolant liquid is short, and heat generated during rolling accumulates, causing the temperature of the work roll and the shape of the metal steel strip to be defective. The temperature is raised above the temperature at which shape defects occur.

As will be explained below, the cold rolling equipment according to the present embodiment, for example, based on the measurement results such as the plate temperature as shown in the lower diagram of FIG. By setting the angle of inclination of the metal steel strip with respect to the biting part, the length of the coolant can be adjusted. By adjusting the length of the coolant flow, the temperature of the metal steel strip falls within the optimum temperature range, suppressing deformation of the work roll and suppressing brittle cracking during rolling.

FIG. 1 is a diagram showing an example of the configuration of a cold rolling mill included in the cold rolling equipment according to the present embodiment. The cold rolling equipment includes one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and a cold rolling mill located upstream of the cold rolling mill in the conveyance direction of the metal steel strip. It includes a plurality of rolls provided on the side for conveying the metal steel strip, and a control device that controls the height difference between the plurality of rolls. Although the number of cold rolling mills included in the cold rolling equipment is not particularly limited, this embodiment will be described assuming that it is four as shown in FIG. 3. FIG. 1 shows an enlarged view of one of a plurality of cold rolling mills included in a cold rolling facility.

As shown in FIG. 1, the height of each of the plurality of rolls on the entrance side of the cold rolling mill can be adjusted by a lifting device. The elevating device is, for example, a screw jack, but is not limited to a specific device. The control device controls the height difference between the plurality of rolls by causing the lifting device to raise and lower the rolls based on the control signal. In the example of FIG. 1, the control device controls the plurality of rolls so that the metal steel strip becomes lower toward the downstream side in the conveyance direction. In the example of FIG. 1, the control device controls the inclination angle to be positive, with the angle of the metal steel strip on the entry side with respect to the horizontal direction of the biting part of the cold rolling mill being defined as the inclination angle. When the inclination angle is positive, the coolant that bounces off the work rolls and flows over the metal strip toward the entry side (upstream side) returns to the biting part of the cold rolling mill due to the inclination. Therefore, the length of the coolant can be shortened. Therefore, the control device controls the metal steel strip to be at a lower position toward the downstream side in the conveying direction at the entrance side of the cold rolling mill where the temperature of the metal steel strip is lower than the optimum temperature. The temperature of the metal steel strip can be increased. Generally, on the inlet side of the most upstream rolling mill provided on the most upstream side, the length of the coolant liquid becomes long, and the temperature of the metal steel strip decreases below the optimum temperature. Therefore, the control device may control the metal steel strip to be at a lower level toward the downstream side in the conveyance direction on the upstream side of one or more cold rolling mills including the most upstream rolling mill. In the example of FIG. 3, the control device raises and lowers the entry side rolls of the first cold rolling mill (most upstream rolling mill) and the second cold rolling mill so that the inclination angle is positive. By shortening the coolant flow length, the temperature of the metal strip can be increased to within the optimum temperature range.

Here, the control device may set the inclination angle of the first cold rolling mill to the same inclination angle as that of the second cold rolling mill, or may set it to a different inclination angle. The control device controls at least the steel type of the metal steel strip, the line speed, the coolant injection flow rate, the temperature of the metal steel strip, and the target temperature of the metal steel strip on the upstream side of one or more cold rolling mills including the most upstream rolling mill. The tilt angle may be set based on one. The control device may set the inclination angle of the first cold rolling mill (the most upstream rolling mill), for example, based on the temperature of the metal steel strip and the target temperature of the metal steel strip. The control device also sets the inclination angle of the second cold rolling mill so that the inclination angle is smaller than the inclination angle of the first cold rolling mill, based on, for example, a difference in line speed. good.

It is preferable that the control device controls the plurality of rolls so that the inclination angle is 2° or more and 10° or less. As shown in the experimental examples described later, when the inclination angle is less than 2 degrees, the degree of shortening of the length of the coolant layer is small and the effect of temperature increase is small. Moreover, if the inclination angle is larger than 10°, smooth conveyance of the metal steel strip may be hindered. When the angle of inclination is 5° or more, there is a possibility that the length of the coolant layer can be shortened by 50% or more. Therefore, the control device may control the plurality of rolls so that the inclination angle is greater than or equal to 5 degrees and less than or equal to 10 degrees.

Here, the length of the sloped portion is preferably a certain length because if it is too short, the coolant may ride over the sloped portion. As an example, the length of the inclined portion is preferably 1 m or more. Further, due to equipment constraints, an upper limit may be set on the length of the inclined portion. As an example, the length of the inclined portion is preferably 3 m or less.

FIG. 2 is a diagram showing another configuration example of a cold rolling mill included in the cold rolling equipment according to the present embodiment. As in FIG. 1, the cold rolling equipment includes one or more cold rolling mills, a plurality of rolls, and a control device. FIG. 2 will be described as an enlarged view of one of a plurality of cold rolling mills included in the same cold rolling equipment as FIG. 1.

The height of each of the plurality of rolls on the entrance side of the cold rolling mill can be adjusted by a lifting device, similar to FIG. 1. In the example of FIG. 2, the control device controls the plurality of rolls so that the metal steel strip becomes higher toward the downstream side in the conveyance direction. That is, in the example of FIG. 2, the control device controls the tilt angle to be negative. When the inclination angle is negative, the coolant that bounces off the work roll and flows toward the entry side (upstream side) on the metal steel strip extends further upstream due to the inclination. Therefore, the length of the coolant can be increased. Therefore, the control device controls the metal steel strip so that it becomes higher toward the downstream side in the conveying direction at the entrance side of the cold rolling mill where the temperature of the metal steel strip has risen above the shape defect generation temperature. By this, the temperature of the metal steel strip can be lowered. Generally, on the inlet side of the most downstream rolling mill, which is installed at the most downstream side, the length of the coolant liquid is short, and heat generated during rolling accumulates, causing the temperature of the metal steel strip to rise above the temperature at which shape defects occur. Rise. Therefore, the control device may control the metal steel strip to be at a higher level toward the downstream side in the conveyance direction on the upstream side of one or more cold rolling mills including the most downstream rolling mill. In the example of FIG. 3, the control device increases and decreases the length of the coolant liquid by raising and lowering the entrance roll of the fourth cold rolling mill (the most downstream rolling mill) so that the inclination angle is negative. The length can be increased to reduce the temperature of the metal strip to within the optimum temperature range.

Here, the control device controls the steel type of the metal steel strip, the line speed, the coolant injection flow rate, the temperature of the metal steel strip, and the target of the metal steel strip on the upstream side of one or more cold rolling mills including the most downstream rolling mill. The tilt angle may be set based on at least one of temperature. The control device may set the inclination angle of the fourth cold rolling mill (the most downstream rolling mill), for example, based on the temperature of the metal steel strip and the target temperature of the metal steel strip. In addition, the control device calculates the optimum length of the coolant liquid based on, for example, the steel type of the metal steel strip, the line speed, and the coolant injection flow rate, and adjusts the length of the coolant liquid to match the calculated value. The inclination angle of the fourth cold rolling mill may be set to .

Preferably, the control device controls the plurality of rolls so that the inclination angle is −10° or more and −2° or less. As shown in the experimental examples described later, when the inclination angle is −2° or more, the degree of extension of the length of the coolant layer is small, and the temperature reduction effect is small. Further, if the inclination angle is larger than -10°, smooth conveyance of the metal steel strip may be hindered. When the inclination angle is −3° or less, there is a possibility that the length of the coolant can be increased by more than three times. Therefore, the control device may control the plurality of rolls so that the inclination angle is −10° or more and −3° or less.

Here, the type of cold rolling mill that the cold rolling equipment is equipped with is not limited. The cold rolling mill may be, for example, a multi-high rolling mill or a reverse rolling mill. Also, different types of cold rolling mills may be included. Even when the cold rolling mill is a reverse rolling mill, the inclination angle for adjusting the length of the coolant layer may be set so as to keep the temperature of the metal steel strip in the optimum range.

Additionally, the cold rolling equipment may have a limiting mechanism to prevent the inclination angle from exceeding a predetermined angle range (for example, −10° to 10°). The limiting mechanism may be, for example, a mechanical stopper, or may be a device that limits the range of motion of the lifting device based on a signal from a detection device such as a proximity switch.

The cold rolling equipment according to the present embodiment is used as a part of steel plate manufacturing equipment, as described above. In addition, the control device of the cold rolling equipment controls a plurality of rolls on the upstream side of one or more cold rolling mills including the most upstream rolling mill so that the metal steel strip is at a lower position toward the downstream side in the conveying direction. A cold rolling method can be carried out, comprising the steps of: In addition, the control device of the cold rolling equipment controls a plurality of rolls on the upstream side of one or more cold rolling mills including the most downstream rolling mill so that the metal steel strip is at a higher position toward the downstream side in the conveying direction. A cold rolling method can be carried out, comprising the steps of: The steel sheet manufacturing equipment can perform a method of manufacturing a steel sheet, which includes performing a cold rolling method and further cutting a metal steel strip.

As described above, the cold rolling equipment, the steel sheet manufacturing equipment, the cold rolling method, and the steel sheet manufacturing method according to the present embodiment adjust the length of the coolant liquid through the above configuration or process (step). to bring the temperature of the metal steel strip within the optimum temperature range. Therefore, deformation of the work roll can be suppressed and brittle cracking during rolling can be suppressed.

Although the embodiments of the present disclosure have been described based on the drawings, it should be noted that those skilled in the art can easily make various changes or modifications based on the present disclosure. For example, functions included in each component can be rearranged so as not to be logically contradictory, and a plurality of components can be combined into one or divided. Embodiments according to the present disclosure can also be realized as a program executed by a processor included in the device or a storage medium recording the program. It is to be understood that these are also encompassed within the scope of the present disclosure.

In the above embodiment, a cold rolling facility including four cold rolling mills has been described with reference to FIG. 3, but the number of cold rolling mills included in the cold rolling facility is not limited. For example, if the cold rolling equipment is equipped with only one cold rolling mill, the control device can control multiple rolls such that the metal steel strip is lowered toward the downstream side in the conveying direction, and Only one of the plurality of rolls may be controlled at higher positions toward the downstream side. In addition, when the cold rolling equipment includes a plurality of cold rolling mills, each of the intermediate cold rolling mills other than the most upstream rolling mill and the most downstream rolling mill has a positive inclination angle according to the control device. It may be adjusted to have a negative inclination angle, or it may be adjusted to have a negative inclination angle, or the inclination angle may not be adjusted.

Hereinafter, the effects of the present disclosure will be specifically explained based on examples (experimental examples), but the present disclosure is not limited to these examples.

(Example)
Using the cold rolling equipment described in the above embodiment, a rolling experiment was conducted to determine whether seizure and plate breakage occur after rolling. The cold rolling equipment used was one equipped with four cold rolling mills as shown in FIG. Table 1 shows the components (mass%) of the target steel types A to C. In Table 1, "Bal." indicates that the remainder is Fe.

A rolling experiment (first experiment) was conducted with the inclination angle changed from 0° to 10°. In the first experiment, the inclination angle of the first cold rolling mill (No. 1std), which is the most upstream rolling mill, was changed. The coolant flow rate was 100 to 300 L/min. The initial temperature of the steel plate (metal steel strip) to be passed was 200°C. The steel plate (metal steel strip) had a width of 1000 mm and an initial plate thickness of 2.0 mm. The line speed was 15 mpm or 100 mpm. The plate thickness was set from 2.0 mm to 1.2 mm by rolling with the first cold rolling mill. The coolant used was a mixture of 5% rolling oil and 95% pure water. The temperature of the coolant was 60°C.

Table 2 shows the results of the first experiment. No. Under condition 1, the liquid riding length was 100 mm or less, but seizure occurred. No. Seizure did not occur under condition No. 5, but the length of the coolant was as long as 600 mm, and the plate temperature at the entrance side was 60°C, a drop of 140°C from the initial temperature, causing the plate to break. No. 3 and no. No. 4 was the result of tilting the pass line, but no burn-in occurred in either case. Also, No. 3 and no. In No. 4, the plate temperature at the entry side was also 80° C. or higher, which was the ductile-brittle transition temperature or higher, and no plate breakage occurred.

Other results are shown in Table 2. In the comparative example, the inclination angle was 0°, and plate breakage occurred with a high probability. From the invention example in Table 2, when the initial temperature of the steel plate (metal steel strip) is 200°C, in order to prevent plate breakage by tilting the pass line, it can be prevented by setting the inclination angle of the most upstream rolling mill to 5° or more. It was found that the effect was even greater. This result is considered to be the same for a cold rolling mill provided in the middle, in which the temperature of the steel plate (metallic steel strip) on the entry side is lower than the ductile-brittle transition temperature.

Further, using the cold rolling equipment described in the above embodiment, a rolling experiment was conducted to determine whether shape defects would occur after rolling. The cold rolling equipment used was one equipped with four cold rolling mills as shown in FIG. Table 1 shows the components (mass%) of the target steel types A to C.

A rolling experiment (second experiment) was conducted with the inclination angle changed from 0° to -10°. In the second experiment, the inclination angle of the fourth cold rolling mill (No. 4 standard), which is the most downstream rolling mill, was changed. The coolant flow rate was 2000 to 3000 L/min. The initial temperature of the steel plate (metallic steel strip) to be passed was 300°C. The steel plate (metal steel strip) had a width of 1000 mm and an initial plate thickness of 2.0 mm. The line speed was 1000 to 1500 mpm. The plate thickness was set from 0.4 mm to 0.3 mm by rolling with the fourth cold rolling mill. The coolant used was a mixture of 5% rolling oil and 95% pure water. The temperature of the coolant was 60°C.

Table 3 shows the results of the second experiment. When the inclination angle was 0° and the plate temperature at the entrance side was 250°C, quarter elongation (shape defect) occurred when the length of the coolant was 400mm. When the inclination angle was -2° and the plate temperature at the entrance side was 250°C, the length of the coolant was 1500mm, and no quarter elongation occurred.

Other results are shown in Table 3. In the comparative example, the inclination angle was 0°, and shape defects occurred with a high probability. From the invention example in Table 3, when the initial temperature of the steel plate (metal steel strip) is 300°C, in order to prevent shape defects by inclining the pass line, the inclination angle of the most downstream rolling mill is set to -2° or less. It was found that the prevention effect was enhanced. This result is considered to be similar to a cold rolling mill that is provided in the middle and in which the temperature of the steel plate (metal steel strip) on the entry side is equal to or higher than the shape defect generation temperature.

Claims

one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; a plurality of rolls provided in the metal steel strip for conveying the metal steel strip, and a control device that controls the height difference of the plurality of rolls,
The control device is configured such that, on the upstream side of at least a portion of the one or more cold rolling mills including the most upstream rolling mill provided on the most upstream side, the metal steel strip is lowered toward the downstream side in the conveying direction. A cold rolling facility that controls the plurality of rolls in such a manner.
The control device controls the steel type of the metal steel strip, the line speed, the injection flow rate of the coolant, and the flow rate of the metal steel strip on the upstream side of at least a portion of the one or more cold rolling mills including the most upstream rolling mill. The cold rolling according to claim 1, wherein the inclination angle of the metal steel strip with respect to the biting part of the one or more cold rolling mills is set based on at least one of temperature and a target temperature of the metal steel strip. Facility.
The cold rolling equipment according to claim 2, wherein the control device controls the plurality of rolls so that the inclination angle is 2° or more and 10° or less.
The one or more cold rolling mills are plural,
The control device is configured such that, on the upstream side of at least some of the one or more cold rolling mills including the most downstream rolling mill provided on the most downstream side, the metal steel strip is positioned at a higher level toward the downstream side in the conveying direction. The cold rolling equipment according to any one of claims 1 to 3, wherein the plurality of rolls are controlled as follows.
one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; a plurality of rolls provided in the metal steel strip for conveying the metal steel strip, and a control device that controls the height difference of the plurality of rolls,
The control device is configured such that, on the upstream side of at least some of the one or more cold rolling mills including the most downstream rolling mill provided on the most downstream side, the metal steel strip is positioned at a higher level toward the downstream side in the conveying direction. A cold rolling facility that controls the plurality of rolls in such a manner.
The control device controls the steel type of the metal steel strip, the line speed, the injection flow rate of the coolant, and the flow rate of the metal steel strip on the upstream side of at least a portion of the one or more cold rolling mills including the most downstream rolling mill. The cold rolling according to claim 5, wherein the inclination angle of the metal steel strip with respect to the biting part of the one or more cold rolling mills is set based on at least one of temperature and a target temperature of the metal steel strip. Facility.
The cold rolling equipment according to claim 6, wherein the control device controls the plurality of rolls so that the inclination angle is −10° or more and −2° or less.
Steel plate manufacturing equipment comprising the cold rolling equipment according to any one of claims 1 to 7 and equipment for cutting the metal steel strip.
one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; A cold rolling method carried out in a cold rolling facility comprising: a plurality of rolls provided at a steel strip for transporting a metal steel strip; and a control device for controlling a height difference between the plurality of rolls.
The control device is configured such that, on the upstream side of at least some of the one or more cold rolling mills including the most upstream rolling mill provided on the most upstream side, the metal steel strip is positioned at a lower level toward the downstream side in the conveying direction. A cold rolling method comprising the step of controlling the plurality of rolls in such a manner.
one or more cold rolling mills that inject coolant toward the work rolls and the metal steel strip to cold-roll the metal steel strip, and an upstream side in the conveyance direction of the metal steel strip than the one or more cold rolling mills; A cold rolling method carried out in a cold rolling facility comprising: a plurality of rolls provided at a steel strip for transporting a metal steel strip; and a control device for controlling a height difference between the plurality of rolls.
The control device is configured such that, on the upstream side of at least some of the one or more cold rolling mills including the most downstream rolling mill provided on the most downstream side, the metal steel strip is positioned at a higher level toward the downstream side in the conveying direction. A cold rolling method comprising the step of controlling the plurality of rolls in such a manner.
A method for manufacturing a steel plate, comprising the step of performing the cold rolling method according to claim 9 or 10 and cutting the metal steel strip.