JPS61179819A - Cooling method of metallic strip - Google Patents

Abstract

PURPOSE:To bring a strip into uniform contact with cooling rolls and to obtain an excellent product shape by applying the largest possible tension to the strip while maintaining the transverse shrinkage of the strip detected on the outlet side of the cooling rolls within a permissible range. CONSTITUTION:The width of the strip on the outlet side of the roll cooling section is detected in a method for cooling the metallic strip by bringing the same into contact with >=1 pieces of the cooling roll in the cooling zone of the continuous annealing installation. The tension of the strip in the roll cooling section is controlled so as to be made max. in the tension range below the yield stress within the range where the transverse shrinkage of the strip obtd. by such width detection does not exceed the permissible value of the product width. The strip is thus brought into uniform contact with the cooling rolls and is uniformly cooled in the transverse direction, by which the product having a goodshape is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cooling a metal strip such as a steel plate, and in particular to a method for contact cooling a steel plate using a cooling roll installed in a cooling zone in continuous steel plate annealing equipment. be.

(Prior Art) The strip unwound from the payoff reel l (or l) is welded by a welding machine 2. Electrical cleaning installation 113. Dryer 4
．． It is introduced into the continuous annealing furnace through the entrance looper 5. This furnace has 6 heating zones, 7 soaking zones, and 8 gas jet cooling zones. Roll cooling zone9. It consists of an overaging zone 12 and a secondary cooling zone 13 through which the strip is subjected to the desired heat treatment. The strip leaving the annealing furnace is passed through an exit looper 14° and a skin pass mill 15. Side trimmer 16.
Invection Department 17. It passes through an oiler 18 and is wound up on a tension reel 19 (or 19).

In the roll cooling zone 9 in the above equipment, a plurality of water-cooled cooling rolls 10 (in some cases, a single piece of wood may be used) and, for example, prydle rolls 11 and 11 that apply tension to the front and rear positions are arranged. is cooled to the required temperature while alternately contacting cooling rolls on both sides.

Note that the technique of applying tension to a steel plate and uniformly cooling the steel plate with a cooling roll has not been disclosed until the technique described in JP-A-59-20428.

(Problem to be Solved by the Invention) Normally, in this roll cooling method, in order to cool the strip uniformly, it is necessary to bring the roll into contact uniformly in the width direction, and for this reason, it is necessary to operate at a relatively high tension. did not become. The tension is within the hot strength of the strip and the tension range is such that the plate does not break (heat buckling does not occur).
However, high tension operation causes width shrinkage of the strip.

Conventionally, the width of the material was determined in advance by considering the amount of width shrinkage, but the amount of width shrinkage varies depending on various conditions and is not constant. Alternatively, the width of the material can be made larger in advance and then trimmed, but since this reduces the yield, the current situation is that trimming is generally not performed unless the width accuracy is extremely strict. Therefore, in the roll cooling of the strip, there has been a strong demand for the development of a means that can reliably maintain the amount of width shrinkage within an allowable range and apply as large a tension to the strip as possible.

The present invention has been made in view of the above circumstances, and provides a cooling method that reasonably achieves the above-mentioned contradictory problems, namely, applying maximum tension while suppressing the amount of width shrinkage within an allowable value. The purpose is to

(Means for solving problems) The cooling method of the present invention is configured as follows.

That is, in a method of cooling a metal strip by bringing it into contact with one or more cooling rolls in a cooling zone of continuous annealing equipment, the width of the strip is detected at the exit side of the roll cooling section, and the width of the strip is detected at the exit side of the roll cooling section. tension without the amount of width shrinkage obtained by the width detection exceeding the allowable value of the product width.

This is a method for cooling a metal strip, characterized in that the tension is controlled to be maximum in a tension range below the yield stress.

The details of the present invention will be explained below based on the drawings.

In the present invention, since the width of the strip is detected at the exit side of the roll cooling section of the continuous annealing equipment as described above,
A strip width detector 2o is installed on the exit side of the final cooling roll in FIG.
Place. As this detector, for example, a pyroscanner is used which can detect the strip width edge by using a water-cooled plate as the background so that the temperature difference between the strip and the background can be identified. Of course, any other width meter may be used as long as it can accurately detect the width.

Since the strip width is detected by the bump width detector 20,
Since the width of the strip at the equipment entry side is known, the amount of width reduction can be measured based on this. In the case of cold-rolled steel sheets and copper strips, there is a permissible range for this width shrinkage, and tension application is permitted as long as it does not deviate from this range. The product width tolerance defined in JIS is as follows.

The amount of width shrinkage varies depending on various conditions such as the material of the strip (yield strength of the material), the plate thickness, and operating conditions (annealing temperature, tension in the furnace, speed (residence time in the furnace), presence or absence of acceleration/deceleration, etc.). Conventionally, for safety reasons, the tension in the roll cooling section was set low so that the amount of convergence would not exceed an allowable value under any conditions.

In contrast, in the present invention, the amount of width shrinkage is constantly detected, so if the amount of width shrinkage is within the allowable value, the tension is increased to the maximum near the limit of the allowable value, and the tension is increased evenly in the width direction of the strip. This makes it possible to cool the rolls. To explain this in Fig. 2, the conventional tension shown by the chain line was set at a low point with respect to the plate thickness, but the present invention
11,・The upper limit of the yield stress (6 kg/
This means that it is possible to adopt a tension in the range (shaded area) where the lower limit is the conventional tension value (mW) and the lower limit is the conventional tension value.

(Example) A material with a product size of 0.7 x 1015+am (charged material width 1022 m1) was placed in a continuous annealing furnace at a tension of 3 kg/ml.
However, as a result of measuring the width at the exit side of the roll cooling section, it was 1019 mm, so the tension was gradually reduced to 4.8 k.
When it was increased to g/m♂, the 1 width became 1017+sm. this.

FIG. 3(a) shows the temperature distribution in the width direction of the strip when roll cooling is performed under the condition (tension: 4.8 kg/.f), and it can be seen that the strip is cooled almost uniformly as shown.

On the other hand, Fig. 3 (0) shows the temperature distribution when the weight was continued at 3 kg/Female, but as shown in Fig. 1, unstable conditions were often observed in the width direction.

In addition, Fig. 4 shows an example of measuring the amount of width shrinkage of a strip with a plate thickness of 0.8 to 1.0 l1, where the solid line shows the example of the present invention and the chain line shows the conventional example. In the example of the present invention, since the tension value is controlled while measuring the width, it can be seen that although the absolute value of the amount of width reduction is large, the variation is small.

(Effects of the Invention) As explained above, according to the present invention, when the strip is cooled in rolls, it is possible to thread the strip by applying the maximum tension while keeping the amount of width shrinkage within the allowable range. This allows the strip to contact the cooling roll evenly and
Cooling is performed evenly in the width direction, and excellent shape properties can be obtained.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an overview of continuous annealing equipment to which the method of the present invention is applied, Figure 2 is a graph comparing the tension ranges of the present invention and the conventional example, and Figure 3 is a plate on the exit side of the roll cooling section. In the graphs showing the temperature distribution, (A) is the present invention and (01 is the conventional example). Fig. 4 is a graph showing a comparison of measurement examples of the width shrinkage of the present invention and the conventional example.・Payoff reel, 2... Welding machine, 3... Electric cleaning equipment, 4... Dryer, 5.14... Looper, 6... Heating zone, 7... Soaking zone, 8...・Gas jet cooling zone, 9... Roll cooling zone, 10... Cooling roll, 11... Prydle roll, 12... Overaging zone, !3... Niiocooling zone, 15... Skin pass mill, IB...side trimmer, 17...inspection section, 18...oiler, 1θ...tension reel.

Claims (1)

[Claims] A method of cooling a metal strip by bringing it into contact with one or more cooling rolls in a cooling zone of continuous annealing equipment, comprising: detecting the width of the strip at the exit side of the roll cooling section;
A method for cooling a metal strip, characterized in that the tension of the strip in the roll cooling section is controlled so that the amount of width shrinkage obtained by the width detection is maximized without exceeding an allowable value for the product width.