JPS6366884B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device suitable for cooling a metal strip running in a line, such as a steel strip in a continuous annealing process or a continuous melt galvanizing process.

BACKGROUND ART As a cooling method for steel strip in continuous annealing treatment and continuous hot-dip galvanizing lines that include heating and cooling steps, a method using a cooling roll has been implemented. As shown in FIG. 5, a cooling roll 1 having an internal water cooling structure is disposed in a continuous annealing treatment line, and cooling water is passed into the interior 1.
While winding and moving the heated steel strip around 2,
This method cools the steel strip by heat conduction between the circumferential surface of the body of the roll and the steel strip. In this case, if the temperature of the steel strip is rapidly cooled from, for example, 650°C to 400°C with one roll, distortion of the steel strip and other problems will occur.
A plurality of rolls are arranged in series, and the temperature drop width of the steel strip in each roll of each stage is set to an appropriate value (for example, 40 to 50
℃), and the processing conditions are controlled so that the temperature is cooled to the target temperature at a predetermined cooling rate by passing through all the rolls.

However, with conventional cooling rolls, it is extremely difficult to cool the entire surface of the steel strip uniformly, and the steel strip tends to lose its shape and become uneven in material quality due to uneven tension distribution in the width direction and longitudinal direction. .
This is because the shape of the steel strip introduced into the cooling roll section is not completely flat in both the strip width direction and the longitudinal direction. However, it is due to the fact that it has a wavy unevenness. That is, at the contact portion C between the cooling roll and the steel strip, as shown in FIG. , a gap S is created between the concavely curved portion b and the roll circumferential surface. 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 in the gap 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 steel strip W becomes
It is sent to the next stage of cooling roll in a state where the unevenness is stronger than before contacting the cooling roll 1.
In the cooling roll portion of the next stage, the unevenness is further strengthened by the speed and speed of cooling of each portion of the contact portion a and the non-contact portion b in the same manner as described above. As a result of such repeated uneven cooling, the shape of the steel strip becomes noticeably deformed, and the cooling effect differs between the contact area and the non-contact area with the circumferential surface of the cooling roll, resulting in a decrease in the resulting steel strip. The material lacks uniformity across the width and length of the plate.

The cooling device of the present invention has been made to solve the above problem, and is characterized by a cooling roll that abuts the back side of the metal band with respect to the cooling roll around which the metal band is wound. One or more metal strips are provided to cool the metal strip from both sides.

The present invention will be described with reference to the drawings. In FIG. 1, reference numeral 2 denotes a cooling roll disposed so as to face the cooling roll 1 and come into contact with the back side of the steel strip W. The cooling roll 1 around which the steel strip W is wound 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 into the internal refrigerant channels 1, 1. This point is not particularly different from that of conventional cooling rolls. Further, the cooling roll 2 disposed opposite to the cooling roll 1 may also have a similar internal refrigerant flow path 2.1. However, the roll body diameter does not need to be as large as the cooling roll 2, and may be relatively small. Note that cooling conditions such as roll peripheral surface temperature are set for the cooling roll 1 and the cooling roll 2 facing it so that they have the same cooling effect on the steel strip.

According to the present invention, the steel strip W is cooled from both sides by the cooling rolls 1 and 2 while being continuously transported. Looking at the contact parts C and C' between the cooling rolls 1 and 2 and the steel strip W, as shown in FIG. while the recess b
becomes a convex portion with respect to the other cooling roll 2, contacts that cooling roll 2, and is cooled. That is,
The steel strip W is cooled under the same conditions with each uneven portion coming into contact with one of the cooling rolls.
Therefore, deformation as in the conventional case is not promoted, and a substantially uniform cooling effect is produced over the entire surface of the steel strip.

When the difference between the temperature of the steel strip to be cooled and the surface temperature of the cooling roll 2 is large, as shown in FIG.
A plurality of cooling rolls 21, 22, 23... may be installed facing each stage of cooling roll 1.

In the device of the present invention, each uneven portion a, b of the steel strip W
are cooled by contact with the cooling rolls 1 and 2, and shrinkage stress is generated equally in each unevenness, and as a result, the steel strip W tends to become flatter than the initial state. If desired, if an appropriate rolling force is applied to the steel strip W by the cooling rolls 1 and 2, flattening will be promoted and the cooling process will be made more uniform.

FIG. 4 shows an example of a general continuous annealing treatment using the cooling device of the present invention. Steel strip W is payoff reel 3
It is unwound from 0, is introduced into a continuous annealing furnace through a surface purification treatment device 31, and is passed through a heating zone 32 and a soaking zone 33.
After being heated and soaked to a predetermined temperature in the primary cooling zone 34, it is relatively gently cooled in the primary cooling zone 34, and then in the secondary cooling zone 35, an appropriate number of cooling rolls 1 and cooling rolls attached to each stage of the cooling rolls are cooled. 2, the cooling device according to the present invention is cooled down to the target temperature at a predetermined cooling rate. After being subjected to a predetermined heat treatment in 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 38.

As an example of continuous annealing treatment using the above continuous annealing equipment, cold rolled steel strip (plate width 1240 mm, plate thickness 1.0 mm)
is transferred at a line speed of 160 m/min, heating zone 32.
After being heated and soaked to 750°C in a soaking zone 33, it was cooled to 650°C in a primary cooling zone 34, and then cooled to 400°C in a secondary cooling zone 35 at a cooling rate of 100°C/sec. However, the cooling roll 1 around which the steel strip of the cooling zone 35 is wound has five stages, and the temperature of the outer circumferential surface of the body is maintained at approximately 200 to 250°C by internal water cooling. Further, each cooling roll 1 is provided with two cooling rolls 2 facing each stage, and the temperature of the circumferential surface of each body is kept cooled at 150 to 200°C. After passing through the cooling zone 35, an overaging treatment of 400°C x 150 seconds is achieved in the overaging treatment zone 37, and in the final cooling zone 38, a cooling rate of 5°C/5°C is achieved by blast cooling.
It was cooled to 130°C in seconds. The shape of the steel strip after the above continuous annealing treatment is almost unchanged from that before treatment, and the wavy irregularities in the width direction and longitudinal direction are approximately 2 mm ± 1.
It is about mm. Furthermore, since uneven cooling of the steel strip is alleviated, the uniformity of the material of the steel strip is also improved compared to the conventional method.

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, and therefore, it is possible to cool the steel strip to a desired temperature at a uniform cooling rate in both the width direction and the longitudinal direction. There is no deformation of the steel strip or uneven temperature distribution due to uneven contact, and the desired uniform cooling process can be achieved. In the above explanation, the continuous annealing treatment of the steel strip was taken as an example, but the cooling treatment of the galvanized steel strip in the continuous hot-melting line,
It is also useful for cooling treatment of metal strips in lines that include heating and cooling processes for various other metal strips.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of the cooling device of the present invention;
The figure is a -arrow explanatory diagram of the abutment part between the cooling roll and the steel strip in the apparatus of the present invention, Figure 3 is a schematic explanatory diagram of another embodiment of the present invention, and Figure 4 is a diagram showing the continuous annealing equipment for the steel strip. A schematic diagram showing an example in which the cooling device of the present invention is applied,
FIG. 5 is a schematic diagram of a conventional cooling device, and FIG. 6 is an explanatory diagram of a contact portion between a cooling roll and a steel strip in the conventional cooling device. 1, 2: cooling roll, 1.1, 2.1: refrigerant channel, W: steel strip.

Claims (1)

[Claims] 1. In a cooling device that cools a metal band by winding a metal band around the body circumference of a cooling roll into which a cooling medium is passed and transporting the metal band, a metal band is placed on the back side of the metal band opposite to the cooling roll. 1 cooling roll in contact with
A metal band cooling device characterized by being provided with one or more pieces.