JPH11129010A - Roll profile control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of radical thermal expansion gradient of work rolls by increasing cooling water quantity of a roll cooling equipment as it approaches the roll position in contact with the rolled material edge portion from the roll position in contact with the center of the rolled material, and cutting off or reducing one part of the cooling water at the non-rolling portion. SOLUTION: From the initial rolling stage, the cooling water quantity of the roll cooling equipment 1 arranged in the body length direction of the work rolls 2 is increased as it approaches the roll position in contact with the edge portion of the rolled material 4 from the roll position in contact with the center of the rolled material within the sheet path. Outside the sheet path, the roll cooing water is closed to control the thermal crown. This makes it possible to solve the problem of radical thermal expansion gradient of the work rolls near the edge portion of the material which occurs in the early stage of rolling and also to control the thermal crown over the entire roll body length to be mild even when the number of pieces rolled increases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces the gradient of thermal expansion near the end of a rolled material that grows rapidly in the initial stage of a rolling unit, and does not depend on the change in the width of the rolled material over the entire rolling schedule. And a roll profile control method for controlling a sheet crown and shape of a rolled material.

[0002]

2. Description of the Related Art As a method for controlling a thermal crown that grows on a work roll during rolling, a conventional technique is generally known in which the amount of roll cooling water is controlled to be uniform over the entire length of the roll body. . When the thermal crown is controlled by this conventional technique, as shown in FIG. 6, the thermal crown behavior rapidly grows particularly in a region in contact with the rolled material at an early stage of rolling (hereinafter, referred to as a sheet path), As a result, the gradient of the thermal expansion of the roll near the end of the rolled material becomes steep. Next, when rolling a rolled material having a greater sheet width than the previous rolled material, the sheet crown of the next rolled material is affected by the thermal crown behavior described above, and the sheet crown is sharply reduced near the end of the pre-rolled material sheet. Thus, there is a problem that a desired plate crown cannot be obtained by the rolling mill. Further, even when the number of rolls is increased, for example, after rolling several rolls of the same width continuously, and rolling a rolled material having a plate width larger than that of the previously rolled material, it is desirable to use a desired rolling mill as described above. However, there is a problem that the sheet crown cannot be obtained, that is, the sheet width schedule cannot be performed.

As another conventional technique for making the thermal crown and roll wear uniform in the roll body length direction, for example, a hot rolling method disclosed in Japanese Patent Application Laid-Open No. 61-92702 is known. In this conventional technique, during a rolling schedule, the shift amount of a work roll is changed stepwise every fixed number, for example, with respect to a mill center as shown in FIG. It will be uniform. In the case of this conventional technique, thermal crown and wear distribution are possible in the effective range of the work roll shift,
Since the shift amount of the work roll at this time is about ± 100 mm (based on a mill center), it is possible to solve the above-described problem when rolling the rolled material continuously and then performing the wide rolling. could not.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and uses an existing strip crown and shape control end throughout the rolling schedule.
An object of the present invention is to provide a thermal crown control technique for a rolling roll in order to obtain a desired sheet crown and shape.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is as follows: (1) In a method for controlling a thermal crown of a work roll, a roll disposed in a body length direction of the work roll. The amount of cooling water of the cooling device is controlled so as to increase as the roll position approaches the roll position contacting the rolled material end from the roll position contacting the rolled material center in the rolled portion of the roll, and in the non-rolled portion of the roll, A roll profile control method, wherein at least a part of the cooling water is cut off or the amount of the cooling water is extremely reduced. (2) A method of controlling the thermal crown of a work roll in a rolling mill having a mechanism for shifting the work roll symmetrically with respect to the roll body length direction by disposing a pair of upper and lower work rolls in the work roll body length direction. The amount of cooling water of the roll cooling device was controlled in the rolling section of the roll so as to increase from the roll position in contact with the center of the rolled material to the roll position in contact with the end of the rolled material, and in the non-rolled portion of the roll. Cuts off at least a part of the roll cooling water or extremely reduces the amount of cooling water, and furthermore, the pair of upper and lower work rolls are rolled one by one or several To
A roll profile control method characterized by inverting right and left. It is.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors first provided a roll profile meter capable of measuring a work roll profile of a hot rolling mill online in order to grasp the growth morphology of the thermal crown in detail. After installation, the thermal crown behavior of the work roll was investigated from the initial stage of the rolling unit. As a result, as shown in FIG. 6, the thermal crown behavior at the initial stage of the rolling unit is almost in the sheet path (the area where the rolled material is in contact with the roll) except for around 50 mm near the end of the rolled material. It was found that the thermal expansion uniformly increased in the roll axis direction, and that a sharp gradient of thermal expansion existed on the end side in the roll axis direction. Further, when a rolled material having the above thermal crown behavior and the width of the next rolled material is larger than the rolling is rolled, the crown of the next rolled material is affected by the roll profile as shown in FIG. As a result, it was found that the crown of the pre-rolled material rapidly decreased in the vicinity of the plate edge. Further, it has been found that such a local and abrupt plate crown fluctuation cannot be corrected even by making full use of the existing operation amount of the crown / shape control end.

Therefore, in order to obtain a roll profile that can be controlled by the existing crown / shape control end, a number of actual machine experiments in which the width direction water distribution of the roll cooling water of the work roll is changed were performed, and the roll profile at that time was set online. Was measured. As a result, as shown in FIG. 1, the widthwise distribution of the roll cooling water in the work rolls increases in the sheet path of the rolls from the roll position in contact with the center of the rolled material toward the roll position in contact with the rolled material edge. It has been found that a desired roll profile can be obtained by controlling the roll cooling water outside the roll path and shutting off the roll cooling water.

FIG. 5 shows a comparison result of the thermal crown behavior between the roll cooling method according to the present invention and the prior art.
That is, if the above-described roll cooling control is performed, the thermal crown behavior gradually decreases from the roll position in contact with the center of the rolled material to the roll position in contact with the end of the rolled material, as shown in FIG. , And outside the board road,
By shutting off the roll cooling water, it is possible to suppress the heat extraction outside the sheet path and promote the thermal expansion due to radiant heat, so that it is possible to eliminate the rapid thermal expansion gradient of the work roll near the end of the rolled material. Was.

When the present invention is applied to a hot rolling line of an actual machine, from the initial stage to the latter half of the rolling unit, the existing crown / shape control ends such as work roll bending force and cross angle, etc. It has been found that by changing the control amount, it is possible to control to a desired plate crown and shape.

In the present invention, as described above, the roll cooling water is cut off outside the sheet road. However, it has been experimentally confirmed that the above-described effects can be obtained even when the cooling water amount is extremely reduced.

The fluid jetting device provided in the work roll body length direction applied to the present invention controls and shuts off the amount of cooling water in the roll body length direction. A switchgear is attached,
Equipment that can be controlled independently is deployed.

According to another aspect of the present invention, a thermal crown control method using the above-described roll cooling method and a pair of upper and lower work rolls are moved left and right with respect to the center in the width direction of the rolled material every one roll or every few rolls. As a result of performing actual rolling in combination with the reverse shift technique, it was found that the thermal crown could be made uniform in the roll body length direction. As a method of shifting the work roll, besides the method shown in FIG. 8, for example, a method disclosed in Japanese Patent Application Laid-Open No. 61-92702 can achieve the same degree of thermal crown uniformity as that of the present invention. Do you get it.

The present invention can be applied not only to the above-described hot rolling mill but also to a cold rolling mill.

[0014]

【Example】

(Embodiment 1) A specific embodiment in which the present invention is applied to hot rolling will be described with reference to FIGS. In the present invention, from the initial stage of rolling, the cooling water amount of the roll cooling device 1 arranged in the body length direction of the work roll 2 is reduced from the roll position in contact with the center of the rolled material in the sheet path as shown in FIG. The thermal crown was controlled so as to increase as approaching the roll position in contact with the end of the material 4, and outside the plate path, the roll cooling water was closed to control the thermal crown. A high-speed roll with extremely low roll wear was used for the work roll, and an online roll profile meter was used for roll profile measurement. FIG. 2 shows a comparison result of the work roll thermal crown behavior according to the present invention and the prior art.

According to the present invention, the gradient of the rapid thermal expansion of the work roll near the end of the rolled material which occurs in the early stage of rolling, which cannot be solved by the prior art, can be eliminated. Even when the number increased, the thermal crown could be controlled more smoothly over the entire length of the roll body than in the prior art. That is, when the present invention is applied, the thermal crown behavior can be gently controlled over the entire rolling schedule, and the existing sheet crown and shape control can be performed even for large sheet width schedule fluctuations, that is, for sheet width schedule free rolling. By changing the control amount of the end, a desired plate crown / shape could be obtained.

(Embodiment 2) Hot rolling was performed by combining the roll cooling method shown in the above-mentioned embodiment 1 and a method of inverting right and left, for example, as shown in FIG. 4 for every three rolls. . As a result, as shown in FIG. 3, the thermal crown was further uniformed in the roll body length direction.

[0017]

As described above, according to the present invention, the gradient of the rapid thermal expansion of the work roll in the vicinity of the end of the rolled material can be eliminated from the initial stage of the rolling unit, and the plate width schedule can be greatly reduced. With respect to the change, the desired crown and shape can be obtained, and the thermal crown can be controlled within the control capability range of the crown and shape control end over the entire rolling schedule.

[Brief description of the drawings]

FIG. 1 is a diagram showing a widthwise distribution of roll cooling water when the present invention is applied.

FIG. 2 is a diagram showing a comparison of roll thermal expansion between the present invention and a conventional technique.

FIG. 3 is a diagram showing an effect of another embodiment of the present invention.

FIG. 4 is a diagram showing a work roll shift method when the present invention is applied to hot rolling.

FIG. 5 is a diagram showing a comparison result between the present invention and a conventional technique at an initial stage of rolling.

FIG. 6 is a view showing a problem of the growth of a thermal crown according to the related art.

FIG. 7 is a view showing a sheet crown caused by thermal crown control according to the related art.

FIG. 8 is a view showing a method of shifting a work roll performed for uniformizing a thermal crown in a roll body length direction according to a conventional technique.

[Explanation of symbols]

 Reference Signs List 1 spray cooling device 2 work roll 3 backup roll 4 rolled material

Claims (2)

[Claims] In a method for controlling a thermal crown of a work roll, a cooling water amount of a roll cooling device provided in a body length direction of the work roll is reduced from a roll position in contact with a center of a rolled material in a roll portion of the roll. The roll is controlled so as to increase as it approaches the roll position in contact with the material end, and in a non-rolled portion of the roll, at least part of the roll cooling water is cut off or the amount of cooling water is extremely reduced. Profile control method. 2. A method for controlling a thermal crown of a work roll in a rolling mill having a mechanism for shifting a pair of upper and lower work rolls symmetrically with respect to the roll body length direction. In the roll section of the roll,
It is controlled so as to increase as it approaches the roll position in contact with the rolled material end from the roll position in contact with the rolled material center, and in the non-rolled portion of the roll, at least a part of the roll cooling water is cut off or the amount of cooling water is extremely reduced. The roll profile control method is characterized in that the pair of upper and lower work rolls are further shifted left and right with respect to the center in the width direction of the rolled material for each rolled material or every several rolls.