JP3260658B2 - Coolant liquid injection method in strip rolling - 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 injecting a coolant liquid in strip rolling, and more particularly to a coolant liquid for reducing a temperature fluctuation of a material to be rolled and enabling a stable temperature control even if a rolling speed changes. The present invention relates to an injection method.

[0002]

2. Description of the Related Art In strip rolling, a pair of upper and lower work rolls are arranged in a plurality of stages, and a cold-rolled material fed between the work rolls is sequentially cold-rolled (including warm-rolled) to form a cold strip. Becomes During this rolling, for the purpose of maintaining lubricity during rolling and cooling the rolls,
The coolant liquid is sprayed toward the work roll or the gap between the work roll and the material to be rolled.

[0003] By the way, cold strips have recently been required to have higher quality than before in terms of surface properties and material properties, and strip rolling requires even more advanced techniques. It has become. In such a situation, depending on the product, the control of the rolling temperature of the material to be rolled has also become an important index.

The most common and effective method for controlling the temperature of a material to be rolled is to control the temperature of a work roll. Conventionally, in the rolling of products that require temperature control of the material to be rolled, the coolant liquid is prevented from scattering near the lower surface of the material to be rolled so that the coolant does not scatter to the material to be rolled and the temperature does not drop. And a rolling plate was provided.

[0005]

However, in the method using such a shield plate, when the rolling speed is increased, the supply of the coolant liquid to the gap between the material to be rolled and the work roll is insufficient. Cause poor lubrication,
On the other hand, when the rolling speed is low, there is a problem that the material to be rolled is supercooled and the temperature cannot be controlled. Therefore, the present invention is to solve the above problems that could not be solved by the prior art in strip rolling,
It is an object of the present invention to propose a method of injecting a coolant liquid that can easily control the temperature of a work roll or the temperature of a cold strip.

[0006]

Means for Solving the Problems In order to effectively control the temperature of the lower work roll in particular, the inventors have intensively studied a method of spraying a coolant liquid, and specified a spray nozzle arrangement and a method of using the spray nozzle. The inventors have found that the above objects can be achieved by setting the conditions, and have completed the present invention.

[0007] In other words, the present invention relates to a strip rolling method using a pair of upper and lower work rolls, in which a coolant is injected from a mill entry side to a lower work roll to cool the lower work roll. A first spray nozzle and a second spray nozzle for lubricating the gap between the lower surface of the material to be rolled and the lower work roll.
The spray nozzle is always used, and the second spray nozzle has a large amount of material to be rolled per unit time.
The temperature drop of the material is small and sufficient temperature control range can be secured.
A method for spraying a coolant liquid in strip rolling, characterized in that the method is used only in rolling at a speed range in which the coolant can flow.

[0008] Here, the coolant spray direction to the lower work roll by the first spray nozzle may be such that, in a cross section perpendicular to the roll axis, the coolant spray direction is lower than the normal direction to the roll surface. It is advantageous.

[0009]

Next, the details of the present invention will be described with reference to FIG. In FIG. 1, a material 1 to be rolled is fed from the right side to the left side of the mill, and is rolled by an upper roll 2 and a lower roll 3. The lower roll is provided with a pair of spray nozzles including a first spray nozzle and a second spray nozzle having different spraying directions.

The first spray nozzle 4 injects only to the lower work roll 3 and has a main purpose of cooling the roll. For this reason, the spraying direction of the spray of the first spray nozzle 4 is lower than the normal direction to the roll surface in the section perpendicular to the roll axis (from the nozzle tip to the lower side) in order to prevent scattering on the material to be rolled. It is desirable that the fuel is sprayed so as to be below the line connecting the center of the work roll). Note that the injection direction here means that this condition is satisfied in the entire area of the coolant spray 7 having a spread. That is, if the upper edge of the coolant spray 7 is sprayed so as to satisfy the above condition, this condition is achieved in the entire area of the coolant spray. If the spraying direction is such that the spraying direction satisfies the above condition, the coolant spray 7 sprayed from the first spray nozzle 4 collides with the lower work roll, becomes a reflective coolant spray 8 and is reflected downward to be rolled. There is no scattering on the material side.

On the other hand, the second spray nozzle 5 is provided for spraying a coolant spray toward a gap between the lower surface of the material to be rolled and the lower work roll for the main purpose of lubrication. At this time, the second spray nozzle 5
The first spray nozzle 4 and the first spray nozzle 4 need to be arranged at positions where the sprays sprayed from the respective nozzles do not collide with each other and interfere with each other.

In the arrangement of the first and second spray nozzles, the first spray nozzle is always used during rolling, and the second spray nozzle is used only during high-speed rolling. As shown in FIG. 1, a coolant liquid is constantly supplied to a first spray nozzle from a coolant tank. On the other hand, a shut-off valve 9 is connected to the second spray nozzle. When the rolling speed is low, the shut-off valve 9 is closed, and when the rolling speed is high, the shut-off valve 9 is opened. Supplied.

Although the first spray nozzle is always used,
The reason why the second spray nozzle is used only at the time of high-speed rolling is as follows. That is, at the time of high-speed rolling, sufficient lubrication is necessary to ensure rollability, and coolant spray to the gap between the material to be rolled and the lower roll is indispensable. At this time, liquid cooling occurs due to the supply of the coolant liquid to the gap portion, but the amount of material to be rolled per unit time is large. For this reason, the temperature reduction amount of the material to be rolled is small, and the temperature control range of the material to be rolled can be sufficiently ensured. On the other hand, at the time of low-speed rolling, the amount of material to be rolled per unit time per unit time is small, and the passage time of the coolant liquid through the liquid cooling section becomes long. The amount of temperature reduction of the material increases, and the temperature control range is significantly narrowed. Therefore, in this case, by stopping the coolant spray to the gap portion and using only the first spray nozzle, the temperature control range of the material to be rolled can be secured. At this time, the lubrication in the gap portion has no problem in rollability because the coolant sprayed to the lower roll by the first spray nozzle adheres to a sufficient degree for lubrication at low speed.

The temperature of the material to be rolled varies depending on the balance between the temperature rise due to the heat generated during processing during rolling and the temperature decrease due to the cooling of the coolant. The calorific value of processing depends on the amount of reduction. If the reduction ratio is constant, the calorific value of processing is constant. Therefore, in order to control the temperature of the material to be rolled,
The amount of coolant to be supplied to the nozzles may be adjusted in accordance with the rolling reduction during rolling under the conditions for use of each nozzle described above.

[0015] Regarding the injection of the coolant liquid to the upper roll, a certain amount of coolant liquid sufficient to cool the upper roll is injected to the roll, and a constant amount of coolant liquid is always generated on the strip. To

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A spray nozzle attached to a lower roll and a spray nozzle attached to an upper roll shown in FIG. It was rolled into a cold strip under the conditions of 70% and a finished plate thickness of 0.5 mm. Here, the strip is rolled at a low speed of 200 mpm and at a high speed of 500 mpm. At a low speed, a coolant liquid is sprayed at a flow rate of 300 l / min using only the first spray nozzle. In both cases, both the first spray nozzle and the second spray nozzle were used together, and the coolant liquid was sprayed at the former flow rate of 500 l / min and the latter flow rate of 500 l / min. Also,
A 5% emulsion was used as the coolant. As a result, the temperature of the material to be rolled measured by the contact type sheet thermometer falls within the temperature range of the target temperature ± 20 ° C., which is far higher than the target temperature ± 40 ° C. which is the conventional technical level, and the predetermined temperature. Sheet temperature control became possible.

[0017]

According to the present invention, even when the rolling speed is changed, it is possible to prevent the supercooling due to the coolant liquid and the reduction of the rolling property (lubricating state), and to control the temperature rolling property of the material to be rolled without impairing it. It is possible to manufacture strips of stable quality.

[Brief description of the drawings]

FIG. 1 is a side view showing an arrangement of a spray nozzle and a method of spraying a coolant liquid.

[Explanation of symbols]

 Reference Signs List 1 rolled material (strip) 2 upper work roll 3 lower work roll 4 first spray nozzle 5 second spray nozzle 6 coolant spray by first spray nozzle 7 coolant spray by second spray nozzle 8 reflective coolant spray 9 Automatic shut-off valve 10 Coolant tank

Continuation of the front page (56) References JP-A-11-267717 (JP, A) JP-A-9-164406 (JP, A) JP-A-7-68310 (JP, A) JP-A-6-292910 (JP, A) JP-A-7-232203 (JP, A) JP-A-9-239403 (JP, A) JP-A-9-239402 (JP, A) JP-A-10-263630 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 27/10 B21B 45/02 310 B21B 45/02 320

Claims (2)

(57) [Claims] In a strip rolling using a pair of upper and lower work rolls, a first spray nozzle for cooling a lower work roll is provided for injecting a coolant liquid from a mill entry side to a lower work roll; A second spray nozzle is provided for the purpose of lubricating the gap between the lower surface of the material to be rolled and the lower work roll, the first spray nozzle is always used, and the second spray nozzle is used for rolling per unit time. Large amount of material passing through, pressure
The amount of temperature drop of the rolled material is small and the temperature control range is sufficiently secured
A method of spraying a coolant liquid in strip rolling, wherein the method is used only in rolling at a speed range in which the coolant can be rolled. 2. The method according to claim 1, wherein the coolant spray direction of the first spray nozzle to the lower work roll is downward in a cross section perpendicular to the roll axis with respect to a normal direction to the roll surface. The method for spraying a coolant liquid according to the above.