JPS59219419A - Cooling method of steel strip - Google Patents

Abstract

PURPOSE:To enable uniform cooling in the transverse direction of a steel strip and to eliminate the need for a post treatment after cooling by providing a cooling circuit and hydraulic circuit concentrical with the surface of a cooling roll body to said body and changing the crown by adjusting the hydraulic power according to the transverse bending shape of the steel strip. CONSTITUTION:Shells 4, 5 are provided on the outside circumference in the shaft part 3 of a cooling roll 1 and spiral grooves 6 are cut on the outside circumferential surface of the shell 5 to constitute a cooling circuit 6 with the inside surface of the shell 4. The circuit 6 is connected to a cooling fluid supplying path 7 and discharging path 8 in the part 3 to cool the roll 1. A hydraulic chamber 9 is formed between the annular cavity 9 provided on the outside surface of the part 3 and the inside surface of the shell 5 and is communicated via passages 10, 10' to the hydraulic passage 11 in the part 3. The transverse bending shape of a steel strip 2 is continuously detected and the oil pressure of the chamber 9 is changed according to the detected shape to adjust the crown of the roll 1, by which the surfaces of the strip 2 and the roll 1 are brought into tight contact with each other over the entire transverse direction and the strip is uniformly cooled.

Description

[Detailed description of the invention] The present invention relates to a method for cooling steel strip.

More specifically, the present invention relates to a method for cooling steel strip in a continuous treatment facility for steel strip, such as a continuous annealing facility for cold-rolled steel strip. For example, cooling a steel strip in continuous annealing equipment requires the ability to rapidly cool the steel strip continuously, for example, in the case of a steel strip with a thickness of 0.8, a cooling capability of 50° C./sec or more is required.

As such cooling methods, methods such as gas cooling, mist cooling, water immersion, and roll cooling have been implemented or devised in the past.

In the gas cooling or mist cooling method, the steel strip is cooled by jetting gas or mist, that is, a steam/water mixed refrigerant, into a cooling zone that the steel strip crosses back and forth several times. However, the cooling ability of gas is low, and in order to obtain a desired cooling rate, it is necessary to set the jet velocity to 80 to 100 m/sec or more, and the power consumption of the blower is enormous. On the other hand, in the case of mist cooling, a large cooling capacity can be obtained by changing the mixture ratio of gas and liquid, but the surface of the steel strip becomes contaminated with oxidation due to contact with liquids such as water, and pickling treatment is required in the post-process. becomes.

With the water immersion method, it is possible to obtain extremely high cooling performance by directly immersing the steel strip in cold water, but it is difficult to control the cooling temperature reached, and pickling in the post-process is unavoidable. It has certain drawbacks. Although a hot water immersion method has been developed to improve this drawback, pickling in the post-process is still considered necessary.

In the roll cooling method, cooling water is flowed inside the hearth roll, and the copper strip is brought into contact with the roll and cooled. This method not only provides a relatively high cooling capacity, but also has the characteristics of low energy consumption and no need for post-process pickling treatment.

(7) However, the shape of the copper strip in the width direction is not necessarily constant, and it is difficult to obtain uniform contact between the cooling roll and the steel strip, so uniform cooling cannot be obtained. Furthermore, the surface temperature of the cooling roll is There is a difference between the end of the roll and the center of the roll, which causes a so-called thermal crown on the roll.The roll surface temperature rises at points where there is good contact with the steel strip, and the roll expands, causing a decrease in the degree of cooling at points where there is poor contact. Differences are becoming more and more prevalent.

If the cooling rate in the middle direction of the steel strip is uneven in this way,
The mechanical properties of the obtained steel strip product also become non-uniform in the middle direction, which is not preferable.

The present invention can be used in continuous annealing equipment for cold-rolled steel strips, and although the cooling energy used is small,
A method for cooling steel strips that has a high-speed cooling capacity of ℃/second or more, enables uniform cooling in the middle direction of the steel strip, and does not require post-treatments such as pickling in the post-cooling process. The purpose is to provide.

According to the present invention, in the method of cooling a steel strip by running the steel strip in contact with the surface of a cooling roll, the cooling roll body has a double shell structure and has at least one core concentric with the surface of the roll. It has two circuits,
One circuit communicates with a cooling fluid supply path and a discharge path provided inside the roll shaft to form a cooling circuit, and the other circuit communicates with a cooling fluid passage provided inside the roll shaft. A cooling roll is used in which the crown of the roll is variable by changing the hydraulic pressure by configuring a hydraulic circuit connected to a hydraulic power source, and the steel strip is cooled at the entrance side of the cooling roll. Detecting the bending shape in the middle direction, adjusting the hydraulic pressure of the cooling roll according to the bending shape to change the roll crown, and performing cooling while keeping the steel strip in close contact with the surface of the cooling roll at all times. A method for cooling a steel strip is provided.

As the cooling roll of the present invention, it is preferable to use a large diameter roll with a large contact surface with the steel strip.

In order to detect the bending shape of the steel strip in the 1↑J direction, the deflation crawl is modified to provide multiple means for detecting the contact pressure with the steel strip in the mid-roll direction, and the shape is determined by these pressure detection signals. (or an optical shape detector may be used).

Hereinafter, the present invention will be explained by way of examples with reference to the accompanying drawings.

FIG. 18 of Attachment 1 is a lateral sectional view of the cooling roll used in the method of the present invention, and FIG. 1B is a side view showing only the shaft portion of the cooling roll in cross section.

The cooling roll 1 runs while the steel strip 2 is wound around its surface.

The inside of the roll 1 has shells 4 and 5 on the outer periphery of the roll shaft 3.
It is equipped with A groove 6 is cut in the outer peripheral surface of the shell 5 in the shape of a cape line, and forms a cooling fluid circuit with the inner surface of the shell 4. The cooling circuit 6 is connected to a cooling fluid supply path 7 and a discharge path 8 provided inside the roll shaft portion 3 to cool the roll 1. It goes without saying that the supply line 7 is connected to a suitable fluid source.

Further, as shown in the figure, the diameter of the discharge passage 8 is smaller than the diameter of the supply passage 7, and the cooling fluid is configured to flow within the cooling circuit 6 at high speed.

According to the invention, the outer surface of the roll shaft 3 is provided with an annular cavity 9, which together with the inner surface of the shell 5 constitutes a hydraulic chamber 9. The hydraulic chamber 9 is connected to the roll shaft 3 through passages 1o and 1o''.
It is connected to a hydraulic passage 11 provided therein. Hydraulic passage 11 is connected to a suitable controllable hydraulic pressure source. When the hydraulic pressure in the hydraulic chamber 8 is changed, the roll crown of the roll 1 is changed accordingly.

surface, cooling fluid supply passage 7, discharge passage 8 and hydraulic passage 12 &
11 is connected via suitable rotary joints (not shown) to external fluid sources, drainage equipment and hydraulic sources, which are well known and will not be discussed in further detail herein.

The hydraulic chamber 9 is divided into a plurality of chambers, for example, three chambers 9a, 9b, and 9C, as shown in FIG. It is possible to control the roll crown shape.

FIG. 3 is a schematic illustration of a method of cooling a steel strip using the cooling rolls shown in FIGS. 18 and 1B to 2 in accordance with the present invention.

The steel strip 2 runs in the direction of the arrow in FIG.
is cooled while in contact with the surface of the deflation crawl 22.
and again traveling in the direction of the arrow for the next processing (
.

The detection roll 21, as detailed in FIG. The amount of roll crown of the cooling roll 1 necessary for the cooling roll 1 to absorb the bending shape of the steel strip in the middle direction and bring it into close contact is calculated from the contact pressure detected when the shape of the bend in the middle direction of the strip 2 is detected. Hydraulic chambers 9 to 9a necessary for that purpose,
The hydraulic pressures 9b and 9c are calculated, and the hydraulic system control means, such as the servomorph 25, is controlled thereby.

In this way, by continuously detecting the bending shape of the steel strip 2 in the rJj direction, the roll crown of the cooling roll 1 is adjusted accordingly, and the surfaces of the steel strip 2 and the cooling roll 1 are always brought into close contact over the entire center direction. Since the steel strip 2 is in contact with
j This results in uniform cooling in the force direction.

FIG. 4 is a schematic cross-sectional view of the curved shape detection roll 21 in the middle direction. The detection roll 21 is arranged on the roll main body 26 in a divided manner in the direction of the roll, and is provided with springs 27a and 2, respectively.
Outside @ 2Ra, 28 supported by 7b, 27c
b-28c, and outer cylinders 28a, 28b, 28
The contact pressure with the steel strip c is measured by the load cells 29a and 29b.
, 29c, and these detection signals are sent to the calculation and control device 24 via signal lines 30a, 30b, 30c.
The bending shape is calculated from the detected pressure.

Note that the outer cylinders 28a, 28b, and 28c do not have to be divided into three parts, but may be divided into as many divided outer cylinders as necessary to more precisely detect the contact pressure in the middle direction with the steel strip. In addition, outer cylinder 2
8a, 2+3b, 28c, 1 of the roll body 26
1] It is sufficient to provide only three locations in the center of the roll and near both ends, even if they do not extend in the entire direction.

Furthermore, the detection of the intermediate beveled shape of the steel strip may be performed on the entrance side of the cooling roll 1 by optical detection means.

FIG. 58 illustrates the difference between the prior art method using a cooling roll with an unchanged roll crown and the method of the present invention shown in FIG. 5B.

FIG. 58 shows a state in which the cooling roll 1 is initially provided with a negative (concave) crown, and the steel strip 2 is in contact with this. In this state, only both ends of the steel strip 2 tend to be cooled.

On the other hand, in the present invention, since the curved shape of the steel strip 2 in the width direction is detected, when the steel strip is flat, the cooling roll 1 is supplied by the hydraulic system so as to make the surface of the cooling roll 1 flat as shown in FIG. 5B. By increasing the hydraulic pressure of the hydraulic oil, the hydraulic chamber 9 is expanded, and the surface of the cooling roll 10 is covered with a steel strip 2 as shown in FIG. 5B.
almost parallel to the surface of Therefore, cooling roll 1
This increases the contact surface between the steel strip 2 and the steel strip 2, thereby increasing the cooling effect and at the same time making it possible to perform uniform cooling.

As mentioned above, in the cooling method of the present invention, a large-diameter cooling roll is used and is always brought into close contact with the surface of the steel strip.
Since the contact surface with the steel strip is larger and a larger amount of cooling water is used, the roll surface temperature becomes uniform, and the steel strip is evenly cooled.

Since the steel strip cooled by the cooling method of the present invention does not come into direct contact with the cooling medium, the surface is kept clean and, of course, no post-treatment such as pickling is required.

It should be noted that the above embodiments of the present invention are merely illustrative and do not limit the technical scope of the present invention in any way, and it goes without saying that the method of the present invention is also applicable to cases other than continuous annealing. Nor.

[Brief explanation of drawings]

FIG. 18 is a lateral sectional view of a cooling roll used in the cooling method of the present invention, and FIG. 1B is a side view showing only the roll axis in cross section. FIG. 2 is a cross-sectional view of another embodiment of the cooling roll used in the method of the invention. FIG. 3 is a schematic illustration of one embodiment of the method of the present invention. FIG. 4 is a schematic cross-sectional view of a detection roll having a mid-curved steel strip used in one embodiment of the method of the present invention. FIG. 58 and FIG. 5B are diagrams for explaining the effects of the method of the present invention, where FIG. 58 shows the case of the conventional method and FIG. 5B shows the case of using the apparatus of the present invention. (Main reference numbers) 1: Cooling roll, 2: Steel strip, 3: Roll shaft, 4.5 steel, 6: Cooling fluid circuit, 9.9a, 9b, 9c: Hydraulic chamber, 21: Width of steel strip Direction bending shape detection roll, 22: Deflation crawl, 24: Calculation and control means, 25: Hydraulic system servo motor, 27a, 27b, 27c: Hane, 28a
, 28b, 28c: split outer cylinder, 29a, 2
9b, 29c: o-docel, applicant Sumitomo Metal Industries Co., Ltd. agent patent attorney Masahiko Arai

Claims (1)

[Claims] In the method of cooling a steel strip without running the steel strip in contact with the surface of a cooling roll, the body of the cooling roll has a double shell structure and has at least two internal circuits concentric with the surface of the roll. One circuit communicates with a cooling fluid supply passage and a discharge passage provided inside the roll shaft to form a cooling circuit, and the other circuit communicates with a cooling fluid passage provided inside the roll shaft. A cooling roll is used in which the crown of the roll is variable by changing the hydraulic pressure by configuring a hydraulic circuit connected to a hydraulic power source through the It is characterized by detecting a curved shape, adjusting the hydraulic pressure of the cooling roll according to the curved shape to change the roll crown, and performing cooling while bringing the steel strip into close contact with the surface of the cooling roll. A method for cooling steel strips.