JPH0692008B2 - Roll coolant supply method for cold rolling mill - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a roll coolant supply method in a cold rolling mill, and in particular, a work roll exchange in which a thermal crown generated in a work roll of a cold rolling mill is unstable. The present invention relates to a method for supplying roll coolant in the immediate transient period.

[Conventional technology]

In a cold rolling mill for cold rolling metal strips, it is necessary to frequently replace work rolls.

Usually, a work roll is provided with a crown, but since a thermal crown is also generated due to processing heat during rolling, the above crown amount is determined in consideration of the thermal crown.

In such work rolls, the temperature of the work rolls did not rise sufficiently due to the accumulation of processing heat immediately after replacement, and the total crown was small, so there was a problem that the rolled shape of the rolled material was not very good. .

When manually controlling the shape control of the rolled material in such a transient period, the roll coolant flow rate is reduced to some extent and rolling is performed for a few coils at a low speed until the roll crown becomes stable. During this time, the rolling load, strip tension, etc. can be adjusted and AGC (Automatic Gauge Con
Wait for the roll crown to stabilize while checking the operation of related equipment. Then, the rolling speed and the roll coolant flow rate are gradually increased from the rolling of the third to fourth coils to start the steady rolling.

On the other hand, in the case of automatic shape control of rolled material, basically, the work roll bender copes with the change of the initial thermal crown, but as in JP-A-55-42162, the flow control of the roll coolant is controlled. There are some that can be used together. In this case, the flow pattern of the roll coolant becomes a concave pattern in the width direction as shown in FIG. That is, since the thermal crown due to the processing heat of the roll is not sufficiently formed in the transient period, the both ends of the roll are cooled more than the central part to increase the crown amount.

[Problems to be Solved by the Invention]

However, in the case of the manual control of the above shape, the operation after the work roll replacement does not necessarily pay attention to only the shape control, and it is easy for the shape defect to occur, and the coolant flow rate with respect to the rolling speed. There is a problem that it is not proper, or rather wear of the roll is accelerated and the roll replacement cycle is shortened.

On the other hand, in the case of automatic shape control, even if the pattern control of the coolant flow rate is performed as described above in the low speed rolling region immediately after the roll exchange, the heat generation amount is small and the working heat is not sufficiently accumulated in the work roll, It becomes difficult to make a difference in the amount of heat removal due to the flow rate distribution, and it cannot be said that the crown control is sufficiently performed. For this reason, the roll bender may exceed the control range of the roll bender, and there is a problem that a defective shape is likely to occur.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a roll coolant supply method capable of obtaining a strip with a good rolled shape even in a transient period immediately after roll replacement. .

[Means for Solving the Problems]

The present invention, in the roll coolant supply method of the cold rolling mill for performing automatic shape control, immediately after the work roll replacement,
While rolling a predetermined number of coils, the roll coolant cooling pattern is manually or automatically operated so as to be a smooth pattern, and the cooling amount is supplied in proportion to the rolling speed, and after the rolling of the predetermined number of coils is completed, The roll coolant supply method for a cold rolling mill is characterized in that the roll coolant cooling pattern is switched to a concave pattern or a convex pattern in the rolling width direction for automatic control rolling.

[Action]

In the present invention, immediately after the work roll is replaced, until the thermal crown is sufficiently formed on the work roll, the cooling pattern of the roll coolant is a smooth pattern, and the cooling amount is increased or decreased in proportion to the rolling speed. The crown stabilizes early.

Therefore, steady rolling in which the rolled shape of the rolled material is good can be easily achieved at an early stage.

〔Example〕

Immediately after exchanging the work rolls, with the work roll bender fixed at a fixed position, the rolls are cooled according to the two types of flow patterns shown in FIGS. When the rolled shape was measured by, and the number of rolled coils until the shape became stable was compared, it was stable at the 5th coil in the pattern of FIG. 2 (a), but in the middle of the 3rd coil of the pattern of FIG. 2 (b). It turned out to be stable at.

This is because the amount of heat removed by the roll coolant is too large in FIG. 2 (a) and it takes time until the thermal crown stabilizes. On the contrary, in the pattern of FIG. 2 (b), the amount of heat removed is a simple pattern. It is considered that this is because the thermal crown could be stabilized at an early stage with a small number.

Therefore, according to the present invention, until the thermal crown becomes stable, the roll coolant is supplied in a smooth pattern as shown in FIG. 2 (b), and after the thermal crown becomes stable, the normal operation is performed as shown in FIG. It was decided to switch to the known convex pattern or the concave pattern shown in FIG.

Although it is in the transient period immediately after the roll replacement, the rolling speed repeats the states of acceleration 10, stability 11, and deceleration 12 as shown in FIG. 4, so it is not possible to suppress the heat removal level of the roll coolant more than necessary. However, it causes troubles such as heat streaks and causes abnormalities in the rolling operation itself.

As shown in FIG. 5, the strip temperature on the delivery side of the rolling mill, that is, the calorific value, changes depending on the rolling speed. Therefore, in the present invention, the heat removal amount by the roll coolant is changed according to the rolling speed.

FIG. 1 is a block diagram of an example of an apparatus capable of suitably implementing the method according to the present invention. The upper and lower work rolls 1 and 2 for rolling the strip 3 are provided with a plurality of coolant nozzles 4 in the width direction.
The coolant supply is controlled by. A speed detector 7 such as a pulse generator (PLG) attached to the deflector roll 6 detects the speed of the strip 3 and inputs the detected value to the process computer 8, and the process computer 8 controls the coolant controller 5.

The process computer 8 stores, for example, a function showing the relationship between the rolling speed and the coolant heat removal level shown in FIG. 6, and calculates the coolant heat removal level according to the speed of the strip detected by the speed detector 7. The result is output to the coolant controller 5. Then, the coolant controller 5 controls the flow rate from each coolant nozzle 4 so that the cooling pattern shown in FIG. The number of coils (for example, 3 coils) to be cooled in a smooth pattern is set in advance in the process computer 8, and when the rolling of this number of coils is completed, the coolant controller 5 is controlled at the coolant heat removal level in the normal rolling state. .

The coolant heat removal level may be changed stepwise as shown in FIG.
It can be changed by controlling the temperature or both of them, and any means may be used.

Further, in the above embodiment, the speed detector 7 is attached to the deflector roll 6, but it may be attached directly to the work roll as shown in FIG.

Further, the change of the coolant heat removal level according to the strip speed may be corrected by the reduction rate or the material of the material to be rolled.

〔The invention's effect〕

According to the present invention, it is possible to more efficiently stabilize the crown of the work roll immediately after the roll is replaced, and in the case of the manual operation, it is possible to reduce complicated operations and operator errors.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus capable of suitably carrying out the method of the present invention, FIGS. 2 and 3 are graphs showing coolant heat removal levels, respectively, and FIG. 4 shows changes in rolling speed with time. A graph, FIG. 5 is a graph showing the relationship between the rolling speed and the outlet plate temperature, FIG. 6 is a graph showing the relationship between the rolling speed and the coolant heat removal level, and FIG. FIG. 8 is a block diagram of an apparatus capable of carrying out the present invention, and FIG. 8 is a graph showing the relationship between the rolling speed and the coolant heat removal level.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Onishi 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Yoshikazu Kiyo 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Chiba Works (56) References JP-A-55-42162 (JP, A) JP-B-53-29295 (JP, B2)

Claims (1)

[Claims] 1. In a roll coolant supply method for a cold rolling mill that performs automatic shape control, a roll coolant cooling pattern is smoothed in a rolling width direction while a predetermined number of coils are rolled immediately after a work roll is replaced. , And the cooling amount is supplied in proportion to the rolling speed, and after the rolling of a predetermined number of coils is completed, the roll coolant cooling pattern is switched to a concave or convex pattern in the rolling width direction for automatic control rolling. A method of supplying roll coolant for a cold rolling mill, comprising: