JPH07106374B2 - Rolling roll cooling method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cooling a rolling roll in a finishing mill for a hot strip mill.

[0002]

2. Description of the Related Art Cooling of a rolling roll in a finishing mill of a hot strip mill is usually performed by injecting a cooling liquid onto a rolling roll from an injection nozzle arranged in the axial direction of the rolling roll. Also, JP-A-62-686
No. 12, JP-A-62-45409, a cooling water jacket is arranged on the outer periphery of the rolling roll, and the rolling roll is cooled by circulating cooling water in the jacket. Further, in the known pump speed control method (hereinafter abbreviated as VVVF method), the cooling water amount during rolling (when the rolled material is bitten) and the cooling water amount during idle operation are smaller than those during idle operation. Cooling rolls can be efficiently cooled by adjusting and changing so as to reduce the amount of cooling water during operation.

However, the above-described cooling technology for the rolling rolls is mainly intended to save the cooling water for the rolling rolls, and does not show any concrete means for improving the surface quality of the hot coil produced. For example, in continuous operation, VV
When the temperature of the rolling roll rises during rolling by the VF method, deterioration and wear of the surface of the rolling roll progress, and the surface quality of the hot coil deteriorates. If the temperature of the rolling roll can be accurately measured, it is possible to perform cooling by the VVVF method without increasing the temperature of the rolling roll, but it is difficult to accurately detect the temperature of the rolling roll. For this reason, even in the VVVF method, when the amount of cooling water is insufficient, there is a problem that the deterioration and wear of the surface of the rolling roll progresses more than expected during continuous operation, and the surface quality of the hot coil deteriorates.

[0004]

As described above, in the continuous operation of the hot strip mill, conventionally, the temperature and wear of the rolling rolls are not checked online,
Excess cooling water is often used to prevent the temperature rise of the rolling rolls, but use of unnecessary cooling water is unavoidable. Since it is difficult to check the surface quality of the hot coil online, it is often the case that a sample is taken from the hot coil after winding up by the sampling method and the surface is inspected offline, but the surface quality is known. When it was discovered that the surface quality of the rolled material had deteriorated due to the long time, the rolling of many hot coils had already been completed.
For this reason, there is a problem that a large number of hot coils whose surface quality is insufficient are inevitably generated.

The present invention has been made to solve these problems, that is, the roll slip water is not unnecessarily excessively used in the continuous operation of the hot slip mill, and the surface quality is excellent. An object of the present invention is to provide a method for cooling a rolling roll that can always stably manufacture a hot coil. By carrying out the method of the present invention, as will be described later, it is possible to extend the life of the rolling roll until the cutting.

[0006]

[Means and Actions for Solving the Problems] In a finishing rolling stand row of a hot strip mill, a rolling roll immediately after being incorporated and before being rolled is grinded to have a roughness of irregularities of, for example, about 10 μ in a preceding stand. ,
The rear stand is finished to a roughness of, for example, about 5μ. The present inventors used a non-contact type laser roughness meter to measure the surface roughness of the rolling roll while being subjected to rolling, but the surface roughness of the rolling roll being used in rolling is , For example, in the rolling roll of the stand in the front stage of finishing,
It was learned that the roughness reached 8 mm to 1.0 mm.

Further, it has been found that the surface quality of the hot coil has an extremely strong correlation with the surface roughness of the rolling roll, and the surface quality of the hot coil can be determined by grasping the surface roughness of the rolling roll.

Further, when the surface roughness of the rolling roll begins to become rough, if the cooling water amount is increased and the rolling roll is strongly cooled, the surface quality of the hot coil is improved, which is different from the case where a smooth rolling roll is used. It was learned that the level was similar, and that the progress of roughening of the rolling roll was remarkably reduced.

The present invention is based on the above findings, namely,
A surface roughness meter that detects the actual roughness of the surface of the rolling roll when the cooling roll is cooled by jetting cooling water from the jet nozzles arranged in the axial direction of the rolling roll of the finishing mill of the hot strip mill. And a computing device that computes the target roughness of the rolling roll required to manufacture a hot coil with a desired surface quality, and a control device that adjusts the cooling water amount and / or the cooling water pressure. A method for cooling a rolling roll, characterized in that the amount of cooling water and / or the pressure of cooling water is controlled based on the difference in degree.

FIG. 1 is an explanatory view of a method for cooling a rolling roll according to the present invention. The rolling roll 4 is heated by the rolled material 9. Since the rolling speed of the front stage stand of the finishing rolling mill train is slow, the contact time with the rolled material 9 is long and the rolling reduction is large. Therefore, heat transfer and frictional heat are large, and heat cracks on the surface layer are particularly large. It is easy to occur.

In the present invention, cooling water is jetted from the jet nozzle 3 arranged in the axial direction of the rolling roll to the rolling roll 4 to cool the rolling roll. The cooling liquid jet nozzle 3 arranged in the axial direction of the rolling roll is formed by arranging a large number of roll cooling water jet nozzles 3 on the roll cooling water header 2 in FIG. 1, for example.

In the present invention, the roughness meter 5 is used to detect the surface roughness (actual roughness) Ri of the rolling roll. As the roughness meter, for example, a non-contact type laser roughness meter can be used, but another kind of roughness meter may be used as long as it can detect the surface roughness of the rolling roll with high accuracy. Roughness meter 5
Detects the actual roughness Ri of the rolling roll at all times or with a constant pitch and transmits the detection result to the control device 8.

In the present invention, the controller 8 increases the cooling water amount or the cooling water pressure of the rolling roll when the actual roughness measured by the roughness meter exceeds the target roughness Ro calculated by the method described later. , Strengthen the cooling of the rolling rolls. This enhanced cooling of the rolling roll has the effect of improving the surface quality of the hot coil during rolling, as described above. Further, by strengthening the cooling of the rolling roll, the progressing speed of the roughening of the rolling roll is remarkably eased.

In the present invention, the target roughness Ro is, for example, when the rolling roll of the pre-finishing stand has an average unevenness of 0.2 mm or more, and the rolling roll of the post-finishing stand has an average unevenness of 0.1 mm or more. More specifically, it is set as a function of the temperature T of the rolled material, the plate thickness H of the rolled material, the rolling speed V of the rolled material, and the rolling pitch P of the rolled material. When the temperature of the rolled material is high, the roughening of the rolling roll is likely to proceed. Therefore, it is preferable to start the cooling of the rolling roll at an early stage. If the rolled material is thick,
When the rolling speed of the rolled material is slow and the rolling pitch is short, the roughening of the rolling rolls easily progresses. Therefore, Ro is set to a small value and the cooling of the rolling rolls is started to be strengthened at an early stage. Ro can also be adjusted by the surface quality Q required for the hot coil to be manufactured.

As described above, the target roughness Ro is T, H,
Since it depends on V, P, Q, Ro is T, H, V,
A relational expression of P and Q, for example, Ro = f (THVPQP)
This relational expression is created in advance based on operational experience or based on operational analysis. This relational expression is input to the arithmetic unit 6 in advance. The computing device 6 computes Ro using the related equation, but the T. H.
V. P. Q is, for example, the upper process computer 7 in FIG.
Input to the arithmetic unit 6. The arithmetic unit 6 calculates Ro and sends it to the control unit 8. The control device 8 has an actual roughness R
i and the target roughness Ro are compared. When Ri <Ro, the roll is cooled with standard cooling water, and when Ri> Ro, a larger amount of cooling water than the standard cooling water or high-pressure cooling water is applied to the rolling roll. Inject to enhance cooling of the roll.

In the present invention, the reference cooling water and the amount or pressure of the cooling water when the cooling is strengthened are not particularly limited, but the present inventors use the cooling water of the ordinary VVVF method as the reference cooling water. As the cooling water for strengthening cooling, the amount of cooling water during idling is not reduced, and the amount of cooling water during idling is made the same as the amount of cooling water during rolling. I was able to extend it.

As described above, according to the present invention, when the cooling water is jetted from the jet nozzles arranged in the axial direction of the rolling roll to the rolling roll of the finishing rolling mill of the hot strip mill to cool the rolling roll, Roughness meter that detects the actual roughness of the roll, a calculation device that calculates the target roughness of the rolling roll necessary to manufacture a hot coil with a desired surface quality, and a control device that adjusts the cooling water amount and / or the cooling water pressure. Is provided and the cooling water amount and / or the cooling water pressure is controlled based on the difference between the actual roughness Ri and the target roughness Ro.

[0018]

When the present invention is carried out, the surface quality of the hot coil can be controlled online, and the surface quality of the hot coil is improved by adjusting the cooling water for the rolling rolls. The coil can be manufactured stably. Further, according to the present invention, since the progress of the roughening of the rolling roll is alleviated, the rolling roll life can be extended. Further, according to the present invention, since the surface condition of the rolling roll can be evaluated online, it is possible to reduce the amount of cooling water that has been conventionally used excessively. Further, according to the present invention, slippage between the rolled material and the rolling roll, which has conventionally occurred due to excessive roll cooling water, can be prevented, and reduction in rolling efficiency due to accidents such as miss rolls can be prevented.

[Brief description of drawings]

 FIG. 1 is an explanatory diagram of a method for cooling a rolling roll according to the present invention.

[Explanation of symbols]

1: Backup Roll, 2: Roll Cooling Water Header, 3: Roll Cooling Water Injection Nozzle, 4: Rolling Roll, 5: Roughness Meter, 6: Computing Device, 7: Upper Process Computer, 8: Control Device, 9: Rolling Material.

Claims (1)

[Claims] 1. When cooling a rolling roll by jetting cooling water to a rolling roll of a finishing rolling mill of a hot strip mill from an injection nozzle arranged in the axial direction of the rolling roll, the actual roughness of the surface of the rolling roll is detected. A surface roughness meter, a computing device that computes the target roughness of the rolling roll required to manufacture a hot coil with a desired surface quality, and a control device that adjusts the cooling water amount and / or the cooling water pressure are arranged. A method for cooling a rolling roll, comprising controlling the amount of cooling water and / or the cooling water pressure based on the difference between the roughness and the target roughness.