JPS60255932A - Device for cooling metallic strip - Google Patents

Abstract

PURPOSE:To obtain the titled device capable of cooling a metallic strip uniformly widthwise and lengthwise by blowing a jet gas against the part of contact between a roll and a metallic strip which is transported along the peripheral surface of the cooling roll. CONSTITUTION:A steel strip W winds along the peripheral surface 1.2 of a cooling roll 1 having a refrigerant passage 1.1 inside, and is transported in the direction as shown by the arrow and cooled. In said cooling device, a nozzle 2 is provided at the inlet side of the steel strip W, and a jet gas G is blown against the part of contact C between the surface of the steel strip W and the peripheral surface 1.2 of the cooling roll 1. Accordingly, a gaseous film is formed between the peripheral surface 1.2 of the roll and the surface of the steel strip W, and the strip is cooled at the part of contact C. Consequently, the steel strip W which is transported is cooled widthwise and lengthwise at a uniform cooling rate, and the deformation and unevenness in quality of the steel strip W is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal strip cooling device suitable for cooling a steel strip in a continuous annealing process for copper strips.

Continuous annealing of steel strips aims to improve the material properties of the steel strips, such as imparting high tension, improving drawability, and workability, and is achieved by heating and cooling the steel strips according to a predetermined heat cycle. Ru.

As a cooling method for the copper strip in this continuous annealing treatment, methods such as immersion in cooling water, spraying with chef's gas, or using a cooling roll having an internal water cooling structure have been implemented. However, with the cooling water immersion method, the copper strip is unnecessarily cooled to a low temperature, and the subsequent overaging treatment requires a large amount of thermal energy to reheat the steel strip to the treatment temperature. On the other hand, the die-end gas spraying method has a rather slow cooling rate, making it unsuitable for annealing high-strength steel, and it also has disadvantages, such as requiring a long period of time for subsequent over-aging treatment.

The method of cooling using a cooling roll has recently become widely used as a method to compensate for the drawbacks of the above-mentioned immersion method and jet gas blowing method.This method uses an internal cooling structure as shown in Figure 6. A cooling roll (1) having the above-mentioned structure is placed in a continuous annealing treatment line, and a heated toner belt is wound around the body surface (1/2) while cooling water is flowing into the interior (1/1). In this method, the copper strip is cooled by heat conduction between the circumferential surface of the body of the roll and the copper strip while moving the copper strip.In this case, the temperature of the strip is changed from 650°C to 400°C with one roll. Rapid cooling can cause distortion of the strip and other problems, so normally a plurality of cooling rolls (1) are arranged in series as shown in the figure, and the temperature of the copper strip is lowered by each roll of each stage. The processing conditions are controlled so that the width is set to an appropriate value (for example, 40 to 50° C.) and the material is cooled to a target temperature at a predetermined cooling rate by passing through all the rolls.

However, it is extremely difficult to uniformly cool the entire surface of the strip by simply transporting the strip in contact with a cooling roll. It is easy to cause deformation and unevenness in the material. This is because the shape of the rope introduced into the cooling roll section is not completely flat in both the sheet width and longitudinal directions, and due to so-called edge elongation and mid-elongation that occur during the original sheet stage and heating process,
This is due to the fact that it is slightly undulating.

Therefore, if we look at the contact between the roll circumferential surface and the steel strip at the abutting part in the cooling roll section, as shown in Figure 7, the part that directly contacts the circumferential surface (l 2) of the cooling roll , and parts that do not touch each other. That is, the cooling roll (1)
The convexly curved part (a) that appears on the circumferential surface of the roller contacts the roll curved surface, and the concavely curved part (b) creates a gap (S) between it and the roll circumferential surface. Ru. Although the figure shows the board width direction, the same applies to the longitudinal direction. The contact portion (a) is rapidly cooled, and the non-contact portion (b) receives the heat insulating effect of the air layer i (S), so that the cooling rate is extremely slow. For this reason, the tension distribution of the steel strip becomes uneven, and as a result, contraction occurs in the strongly cooled contact area (a), and as a result, the copper strip (W)
It is sent to the next cooling roll in a state where the unevenness is more intense than before it contacts the cooling roll (1). In the cooling roll portion of the next stage, the unevenness is further strengthened due to the difference in speed of cooling between the contact portion and the non-contact portion, as described above. As a result of repeated uneven cooling, the shape of the copper strip becomes noticeably deformed, and the annealing effect differs between the contact area and the non-contact area with the circumferential surface of the cooling roll.As a result, the material of the resulting strip becomes This results in a lack of uniformity across the width and length of the board.

The present invention has been made to solve the above problems.

The uninvented metal strip cooling device includes a nozzle on the inlet side of the metal strip in the cooling roll section for spraying jet gas toward the abutment area between the circumferential surface of the cooling roll body and the surface of the copper strip. The present invention is characterized in that the jet gas from the nozzle forms a gas film between the roll circumferential surface and the surface of the copper strip at the abutting portion to transfer the wire strip.

The present invention will be explained with reference to the drawings. In Fig. 1, (2) is a jet gas nozzle. The copper strip (W) passed through the cooling roll (1) is introduced into the cooling roll section as shown by the arrow. In other words, the nozzle (2) is located on the rope entrance side of the cooling roll section, and its gas outlet is directed toward the abutment area (C) between the circumferential surface of the cooling roll (1) and the surface of the rope (W). will be installed. The cooling roll (1) has an internal cooling structure, and the outer circumferential surface of the roll is cooled and maintained at a predetermined temperature by a refrigerant such as water passed through the internal refrigerant flow path (1N). It is not particularly different from that of a cooling roll.

According to the present invention, the copper strip (W) is continuously transferred from the nozzle (2) to the contact between the cooling roll (1) and the copper strip (W). Jet gas (G) is blown toward the contact portion (C). This jet gas (G
), as shown in Fig. 2, a gas film (F) is formed between the circumferential surface of the cooling roll (1) and the surface of the steel strip (W) at the contact portion (C). , the gas till! (F) The cooling roll (]) circumferential surface and the convex portion Ca of the copper strip (W)>
There will be no contact with. This non-contact state is formed intermittently in extremely rapid cycles. Convex part (a
) is repeatedly brought into contact with the roll circumferential surface and in a non-contact state due to the gas film, so that the cooling rate of that part becomes slower than when jet gas is not blown. On the other hand, a gap (S
) is provided with jet gas (G) as a refrigerant, thereby increasing the cooling rate of that part.

In this way, the two effects of relaxing the cooling rate at the convex portions (a) of the copper strip (W) and increasing the cooling rate at the concave portions (b) combine to flatten the cooling rate distribution of the copper strip (W). result,
The wavy irregularities of the steel strip (W) are not strengthened, and by passing through the cooling rolls of each stage in sequence, an even cooling process is achieved.

The jet gas (G) used in the present invention is usually air, but if it is necessary to prevent oxidation of the steel strip surface, an inert gas such as nitrogen gas may be used. The jet gas (G) spraying conditions may be set appropriately, but generally the discharge pressure is 2000 to 50QQ+uAq and the spraying amount is 10
Good results can be obtained under conditions of ~30 rrf/min.

It is preferable that the cooling roll (1) in the present invention has a roughened body peripheral surface. This is because the rough surface makes the gas film (F) more stable, and the cooling effect in the convex portions (a) and concave portions (b) of the rope (W) becomes more uniform. The rough surface is formed by, for example, shot or knurl processing. Drilling grooves is also effective as another method for roughening the surface. Figure 4 shows an example of grooves (1 and 3) being spirally drilled on the circumferential surface, and Figure 5 shows spiral grooves (1 and 3).
This is an example where the holes are crossed.

FIG. 3 shows an example of a general continuous annealing facility to which the cooling device of the present invention is applied. The copper strip (W) is unwound from a payoff reel (30), introduced into a slave annealing furnace through a surface purification treatment device (31), and heated to a predetermined temperature in a heating zone (32) and a soaking zone (33). After being uniformly heated, it is gently cooled in the secondary cooling zone (34), and then in the secondary cooling zone (35), the cooling roll group (1) with an appropriate number of stages and the jet gas nozzle (2) attached to each roll are cooled. With the cooling device of the present invention having
It is cooled down to the target temperature at a predetermined cooling rate. Then, after being subjected to a predetermined heat treatment in a reheating zone (36) and an overaging treatment zone (37), it is cooled in a final cooling zone (38) and wound onto a take-up reel (39). It goes without saying that the cooling device of the present invention may also be used in the final cooling zone (3 days).

As an example of continuous annealing treatment using the above continuous annealing equipment,
A cold-rolled steel strip (width 1240 x 1, plate thickness 0.8 fl) was transferred at a line speed of 200 m/min, heated and soaked at 750°C in the heating zone (32) and soaking zone (33). , - cooled to 650°C in the secondary cooling zone (34), then cooled to 400°C at a cooling rate of 100°C/sec in the secondary cooling zone (35).
Cooled to ℃. However, there are five stages of cooling rolls (1) in the cooling zone (35), and the outer circumferential surface of the body of each roll is maintained at approximately 200 to 250°C by internal water cooling, and the inlet jet gas nozzle (2 ) The blowing pressure of compressed air (at room temperature) is 3500 uAq, and the blowing amount is 20 d/
Adjusted and held for minutes. After cooling, an overaging treatment of 400°C x 150 seconds was achieved in the overaging treatment zone (37), and cooling was performed at a cooling rate of 5°C/sec to 150°C by blast cooling in the final cooling zone (38). . The shape of the copper strip after the above-mentioned continuous annealing treatment is almost unchanged from that before the treatment, and the wavy unevenness in the width direction and longitudinal direction is about 21-±l+n.

By alleviating uneven cooling of the copper strip, compared to conventional methods,
The uniformity of the material of the steel strip is also improved.

As described above, according to the present invention, a steel strip can be cooled to a desired temperature at a uniform cooling rate in both the width direction and the longitudinal direction. The desired uniform continuous annealing process can be achieved without causing deformation of the copper strip or uneven temperature distribution. In the above explanation, continuous annealing of a copper strip was taken as an example, but
Needless to say, it is also useful for cooling various metal strips, such as cooling copper strips after continuous hot-dip plating.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the cooling device of the present invention, FIG. 2 is an explanatory diagram of the contact portion between the cooling roll and the steel strip in the device of the present invention,
Fig. 3 is a schematic diagram showing an example in which the cooling device of the present invention is applied to copper strip continuous annealing equipment, and Figs. 4 and 5 are schematic diagrams showing an example of the circumferential surface of the body of the cooling roll in the present invention. , FIG. 6 is a schematic diagram of a conventional cooling device, and FIG. 7 is an explanatory diagram of a contact portion between a cooling roll and a toning band in the conventional cooling device. l: cooling roll, 1/3: groove, 2: nozzle, G nitrogen gas, W: steel strip. Agent Patent Attorney Arata Miyazaki Department Figure 1 Figure 2

Claims (1)

[Scope of Claims] +11 A cooling device that cools the metal band while winding the metal band around the circumference of a cooling roll having an internal cooling structure and transporting the metal band, the cooling device comprising: a cooling roll having an internal cooling structure on the inlet side of the metal band; A nozzle is provided for spraying jet gas toward the contact portion of the metal strip surface, and the jet gas from the nozzle forms a gas film between the roll circumferential surface and the metal strip surface at the contact point. A metal band cooling device characterized in that the metal band cooling device is configured to transfer the band while moving the band. (2) The metal strip cooling device according to item (11) above, wherein the cooling roll has a circumferential surface roughened with a large number of irregularities.