JP3153478B2 - Method and apparatus for cooling stainless steel strip - 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 and an apparatus for cooling a stainless steel strip, and more particularly, to a cooling technique performed after annealing a cold-rolled stainless steel strip and before pickling.

[0002]

2. Description of the Related Art Generally, in the production of a stainless steel strip (hereinafter simply referred to as a steel strip), annealing and pickling are continuously performed after cold rolling in order to secure a certain quality. Therefore, the steel strip after annealing needs to be cooled before pickling, and the cooling is performed downstream of the annealing apparatus 1 and upstream of the pickling apparatus 2 as shown in the annealing pickling line in FIG. Usually, a cooling zone 3 is provided at the position where the cooling zone 3 is provided, and air cooling and / or water cooling is usually performed. That is, as shown in FIG. 3, a cooling fluid 5 (air or water) is sprayed from above and below onto the steel strip 4 running in the cooling zone 3, and heat is removed from the steel strip 4 to be cooled. In the cooling zone 3, a support roll is often not provided in order to prevent the steel strip 4 from being flawed.

[0003] In addition, in the case of ordinary steel, so-called roll cooling has been proposed in which a support roll of a steel strip running in a cooling zone is a metal water-cooled roll in order to make the above cooling more powerful ( See JP-A-59-54374 and JP-A-61-243128. However,
In such roll cooling, since the steel strip is arranged to be wound around the water-cooled roll, the length of the cooling strip is increased, and the installation of the water-cooled roll is considerably expensive. Further, in stainless steel, the demand for surface quality is high, so that the steel strip does not like to contact such a metal roll. For this reason, stainless steel is generally cooled by air cooling (including gas cooling) or water cooling as described above.

However, in air cooling or water cooling which is usually employed for cooling a stainless steel strip, when cooling a steel strip 4 having a small thickness (0.4 mm or less in thickness), a thermal strain caused by a temperature distribution in a width direction is generated. In many cases, the buckling stress caused by buckling occurs in the width direction of the steel strip. Since this break cannot be corrected in a subsequent step, the steel strip 4 produced with great care becomes scrap, resulting in a reduction in production yield and an increase in production cost.

[0005]

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a method for cooling a stainless steel strip which does not break in the width direction of the steel strip.

[0006]

Means for Solving the Problems The inventor of the present invention has made intensive studies to achieve the above-mentioned object, and has performed cooling while forcibly smoothing the upward bending of a steel strip by running with a physical force. Then, it was found that breaking in the steel strip width direction can be prevented. The present invention embodies this finding, in which cold rolling is performed, and a cooling fluid is sprayed from above and below onto a stainless steel strip running in a cooling zone after annealing and before pickling to cool the steel strip. In doing so, a plurality of support rolls for supporting the steel strip are provided in the cooling zone, the amount of cooling fluid sprayed from the upper side is made larger than the amount from the lower side, and the steel strip is pressed against the support roll, This is a method of cooling a stainless steel strip, wherein the stainless steel strip is cooled while running smoothly.

[0007] Further, the present invention provides a method for cooling a steel strip which is subjected to cold rolling from above and below onto a stainless steel strip running in a cooling zone after annealing and before pickling. The belt is provided with a plurality of support rolls that can be raised and lowered, and the contact between the support roll and the steel strip is adjusted according to the plate thickness to change the support interval between the steel strips, so that the steel strip runs smoothly. And cooling the stainless steel strip.

[0008] Further, there is provided a method for cooling a stainless steel strip, wherein the support interval of the steel strip is changed according to the thickness of the steel strip. In addition, the present invention provides a stainless steel strip comprising a group of nozzles that are subjected to cold rolling, and run in a cooling zone after annealing and before pickling, and spray a cooling fluid onto the steel strip from above and below. The cooling device according to the above, wherein a plurality of vertically movable support rolls for supporting the traveling steel strip are provided in the cooling zone.

In the present invention, the method and apparatus for cooling a steel strip running in the cooling zone are as described above, so that the running steel strip can always maintain smoothness even if it has thermal strain. Therefore, breakage due to planar buckling in the width direction of the steel strip does not occur.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an apparatus for carrying out a method for cooling a stainless steel strip according to the present invention. It is provided with a plurality of vertically movable support rolls 6 inside a cooling zone 3 provided with a cooling device 7 composed of a group of nozzles from which a cooling fluid 5 blows out, and supports a steel strip 4 running on the rolls 6. I made it. The reason why the support roll 6 was made to move up and down freely was
The steel strip 4 has a different sagging state in the cooling zone depending on its thickness. That is, since the steel strip 4 having a large thickness has a small sag and is large if the thickness is small, the number of supports of the steel strip 4 is changed by the thickness. is there. Normally, when the steel strip 4 having a thickness as large as 0.4 mm or more is passed, the support roll 6 may be hardly used, but when the steel strip 4 having a small thickness is passed, the support roll 6 may be used. It was possible to support it. Although not shown in FIG. 1, means for elevating and lowering the support roll 6 is provided by using a mechanism using a known hydraulic cylinder to support and elevate the roll 6 from the side surface of the cooling zone 3. You can do it. Further, in the present invention, each support roll 6 needs to be individually movable up and down.

The first invention is an effective method when the steel strip 4 is relatively thin. As shown in FIG. 1, the cooling fluid from the cooling device 7 located above the upper surface of the steel strip is used. The steel strip 4 is brought into contact with a plurality of support rolls 6 adjusted to the same height by making the amount of 5 larger than the amount sprayed from below onto the lower surface of the steel strip, thereby making the steel strip surface horizontal and smooth. It cools down.

Next, according to a second aspect of the present invention, the support roll 6 is moved up and down according to the thickness of the steel strip 4 under the condition that the spraying of the cooling fluid 5 is made uniform in the vertical direction as in the prior art. (Support interval of the steel strip) is changed to cool the steel strip 4 so as to maintain the horizontal and the smoothness of the surface thereof. The number of rolls 6 to be brought into contact is changed according to the plate thickness, and the change can be easily determined based on the conventional plate thickness and empirical data of the amount of sag.

Further, the third invention is a combination of the above two inventions, wherein the adjustment of the amount of the cooling fluid 5 and the change of the number of contacts with the support roll 6 are simultaneously performed. It is. FIG. 2 shows the state of implementation. FIG. 2A shows the case of a steel strip 4 having a very large thickness.
This is an example in which the position of all the support rolls 6 is lowered so that the rolls 6 and the steel strip 4 are completely out of contact with each other, and the horizontal and surface smoothness of the steel strip 4 is maintained. In this case, conventional cooling without using the present invention is sufficient. Here, the reason why the support roll 6 is lowered with the steel strip 4 having a large thickness to break the contact with the steel strip 4 is to reduce the probability of inadvertently generating roll flaws.

On the other hand, FIG. 2B shows a steel strip 4 having an extremely thin plate thickness.
In the third embodiment, the height of the support rolls 6 is changed in the cooling zone, the steel strips 4 are brought into contact with all the rolls 6, and the interval between the rolls 6 is shortened. At the same time, the amount of cooling fluid sprayed above the steel strip surface is made larger than the amount to the lower surface, and the horizontal and surface smoothness of the steel strip 4 is maintained.

[0015] These inventions were practiced in the production of SUS304 stainless steel strip. The apparatus used was one in which three vertically movable support rolls 6 were installed at intervals of 2.5 m in a cooling zone. Table 1 collectively shows the plate thickness, the difference between the vertical flow rate of the cooling fluid, the number of contacts between the steel strip 4 and the support roll 6, and the state of occurrence of buckling. Table 1 also shows the case where the same sheet thickness is cooled by the conventional method. However, there was no occurrence of buckling in the width direction of the steel strip, which was a problem, and the productivity of the stainless steel strip was greatly improved. It is clear that.

[0016]

[Table 1]

[0017]

As described above, according to the present invention, the bending of the stainless steel strip after cold rolling in the width direction of the steel strip due to flat buckling can be suppressed by cooling before annealing and after pickling. Was. As a result, the production of the stainless steel strip can be performed stably and smoothly, and the productivity has been improved.

[Brief description of the drawings]

FIG. 1 is a side view showing a cooling zone according to the present invention.

FIG. 2 is a side view showing a cooling state of a steel strip in a cooling zone, (a) cooling an extremely thick steel strip by a conventional method,
(B) is an example in which the present invention is applied to a steel strip having a small thickness.

FIG. 3 is a side view showing a conventional cooling zone.

FIG. 4 is a side view showing the outline of an annealing pickling facility for a stainless steel strip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Annealing apparatus 2 Pickling apparatus 3 Cooling zone 4 Steel strip (stainless steel strip) 5 Cooling fluid 6 Support roll 7 Cooling apparatus 8 Looper 9 Shear 10 Tension reel 11 Outgoing deflector roll 12 Welding machine 13 Payoff reel

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-142750 (JP, A) JP-A-6-184650 (JP, A) Japanese Utility Model Application No. 56-11256 (JP, U) Japanese Utility Model Application 147249 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 1/00, 9/56, 9/573 B21B 45/02

Claims (4)

(57) [Claims] 1. A cooling fluid is sprayed from above and below onto a stainless steel strip that has been subjected to cold rolling and is traveling in a cooling zone after annealing and before pickling, and when cooling the steel strip, Providing a plurality of support rolls for supporting the steel strip, making the amount of cooling fluid sprayed from the upper side larger than the amount from the lower side, pressing the steel strip against the support rolls, running the strip smoothly, and cooling it. A method for cooling a stainless steel strip. 2. A cooling fluid is sprayed from above and below onto a stainless steel strip which has been subjected to cold rolling and is traveling in a cooling zone after annealing and before pickling, and when cooling the steel strip, the cooling zone is raised and lowered. Provide a plurality of free support rolls, adjust the contact between the support rolls and the steel strip according to the plate thickness, change the support interval of the steel strip, run the steel strip smoothly, and cool it. A method for cooling a stainless steel strip. 3. The method of cooling a stainless steel strip according to claim 1, wherein the support interval of the steel strip is changed according to the thickness of the steel strip. 4. Cooling of a stainless steel strip comprising a group of nozzles which are cold-rolled and run in a cooling zone after annealing and before pickling, and spray a cooling fluid from above and below the steel strip. An apparatus for cooling a stainless steel strip, comprising a plurality of vertically movable support rolls for supporting a running steel strip in the cooling zone.