JPH0716682B2 - Continuous warm rolling equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous warm rolling facility capable of reducing fluctuations in strip thickness during rolling of steel strip.

[Conventional technology]

Generally, a general cold rolled steel strip is manufactured by rolling a hot rolled steel strip that has been pickled. Further, in the case of stainless steel strip, after hot rolling, it is annealed and pickled, and then cold rolled.

Cold rolling is usually performed by a tandem rolling mill in the case of ordinary steel, and is performed in a high pressure rolling mill such as a Sendzimir rolling mill in the case of stainless steel having high deformation resistance.
Recently, from the viewpoint of improving the production volume, stainless steel has also been oriented to rolling by a tandem rolling mill.

By the way, as the high pressure rolling is performed, the production amount is improved and the manufacturing cost is reduced, but on the other hand, the work hardening of the steel sheet is increased and the rolling load is remarkably increased in the latter stage stand of the tandem rolling mill. Furthermore, the occurrence frequency of steel plate breakage increases and an unfavorable state occurs during operation.

Further, in the case of a complete continuous tandem rolling mill in which a welding machine is installed on the inlet side of the tandem rolling mill and continuously cold-rolls, the steel plate breakage as described above causes a further serious problem in operation.

As a means for solving such a problem, for example, Japanese Patent Laid-Open No.
There is a facility disclosed in Japanese Patent Laid-Open No. 118259. It is equipped with a rolling machine such as Sendzimir mill, planetary mill, pendulum mill, which can be operated under high pressure, on the inlet side of the tandem rolling machine. It is equipped with a heating device that maintains the temperature for the time above which recrystallization does not occur, and heats the strip work-hardened by rolling in the first-stage high-pressure rolling mill to reduce deformation resistance. After doing
Roll with a second stage tandem rolling mill.

[Problems to be solved by the invention]

However, in the rolling equipment disclosed in JP-A-53-118259, since the strip is heated to a temperature of 200 ° C. or higher, it is oxidized by oxygen in the atmosphere to generate a temper color, and the surface There is a problem that it is not good in terms of quality.

In addition, the smaller the distance between the heating device and the tandem rolling mill, the smaller the temperature drop of the steel sheet between them, which is convenient for processing, but it is difficult to prevent the meandering of the steel strip. Since the meandering of the steel sheet causes the steel sheet to break during rolling or the rolled shape of the steel sheet becomes poor, generally, a method of correcting the meandering of the steel sheet by providing a steering device near the entrance side of the tandem rolling mill is recommended. Has been taken. The reason is that if the heating device is small, the steering device, the heating device, and the tandem rolling mill can be arranged in that order. However, in a high-speed line, the passing speed of the steel sheet is large, so the heating device becomes large and the steering device causes meandering. Even if the correction is made, meandering occurs again before passing through the heating device and reaching the rolling mill.

However, when the steering device is installed on the entrance side of the tandem rolling mill as in the above-mentioned general example, the path length of the steel strip from the heating device to the tandem rolling mill becomes large. Such rolling equipment is shown in FIG.

In the figure, 3 is a welding machine for connecting the steel strip S fed from the rewinding machine, 4 is a looper for storing the steel strip S, 5 is a heating device, 6 is a steering device which is a meandering prevention device,
8 is a tandem rolling mill. In this equipment, the path length of the steel strip S between the heating device 5 and the tandem rolling mill 8 is
At least 15 to 20 m.

Further, in the completely continuous tandem rolling mill, as shown in FIG. 5, the strip running speed of the steel strip is changed into patterns such as (a) acceleration, (b) high speed, (c) deceleration, and (d) low speed. It is common to perform repeated operations. This depends on the capacity of the looper 4 or the presence or absence thereof, but due to the welding process of the steel strip on the inlet side and the shearing process of the steel strip on the outlet side, the inlet side equipment may be temporarily stopped or the outlet side equipment may be stopped. This is because it takes time to drive at a low speed. Further, when rolling the welded portion of the steel strip, it is easy to break, so it is necessary to reduce the rolling speed. Therefore, since the passage time of the steel strip between the heating device 5 and the tandem rolling mill 8 changes depending on the rolling speed pattern,
The amount of temperature drop of the steel strip during this period also changes. Therefore, there has been a problem in that the sheet resistance of the steel strip after rolling also fluctuates because the deformation resistance during rolling also fluctuates. (Note that the rolling schedule in the tandem rolling mill is generally set by considering that the deformation resistance of the steel strip is constant.) The present invention has been made in view of such conventional problems. Therefore, an object of the present invention is to solve the above-mentioned problems by providing a second heating device in the vicinity of the entrance side of the rolling mill.

[Means for solving problems]

The present invention relates to a first heating device for heating a steel strip according to a processing sequence between a rewinding machine and a tandem rolling mill, a meandering prevention device for preventing the meandering of the steel strip, and a steel strip dropped by cooling. The second heating device for raising the temperature of 1 to the temperature before being left to cool or higher is a continuous warm rolling facility which is sequentially arranged.

[Action]

The steel strip rewound by the rewinding machine is heated to a predetermined temperature in the first heating device through a welding machine, a looper and the like, and then is prevented from meandering by a steering device which is a meandering prevention device. The steel strip is cooled by passing through the steering device and its temperature is lowered. After passing through the steering device, the steel strip enters a second heating device where it is heated to the temperature before cooling or higher. Then, in a state where the deformation resistance is lowered by heating, the tandem rolling mill enters and is rolled. Therefore, even if the rolling speed of the tandem rolling mill changes,
Since the deformation resistance is small, the plate thickness of the steel strip does not change.

〔Example〕

The present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view of an embodiment according to the present invention, and FIG. 2 is a diagram showing a change in deformation resistance of a steel strip due to heating. FIG. 3 shows another embodiment. The same parts as those in the conventional example are designated by the same reference numerals, and duplicate description will be omitted.

In the figure, the pickled hot-rolled steel strip 2 goes through the following steps according to the processing order. That is, the steel strips 2 unwound from one or a plurality of unwinders 1a and 1b are connected at their ends by a welding machine 3 to form a continuous body and enter the looper 4. The looper 4 is capable of expanding and contracting the passage of the steel strip, so that the residence time of the steel strip in the looper 4 is adjusted as necessary. Next, the steel strip enters the large first heating device 5 by the looper 4, where it is heated to a predetermined temperature (not exceeding 200 ° C.) and then the steering device for correcting and preventing the meandering of the steel strip 2 ( Meandering prevention device)
Pass 6. Then, the steel strip whose temperature has decreased due to cooling while passing through the steering device 6 is
In the heating device 7, the temperature is raised to the temperature before being left to cool, and rolling is performed by the tandem rolling mill 8 in a state where the deformation resistance is reduced.
The rolled strip 10 is cut by the running shear 9 and wound on the winders 11a and 11b.

Now, assuming that the path length of the steel strip 2 passing through the steering device 6 is, for example, 20 m, the amount of temperature decrease due to cooling in the atmosphere is about 1 ° C./sec, so when the strip velocity is 500 m / min. The temperature drop of the steel strip in Similarly, if the steel strip speed is 50 m / min, Becomes That is, when the strip speed is 500 m / min and 50 m / min, a temperature difference of about 20 ° C. occurs on the inlet side of the tandem rolling mill, and therefore the deformation resistance also varies (see FIG. 2) and the strip 10 The result has a great influence on the final plate thickness of. Therefore, in order to prevent the decrease in temperature that causes this, a small-sized second heating device according to the present invention is arranged near the entrance side of the tandem rolling mill 8.

Furthermore, since the steel strip temperatures in the heating devices 5 and 7 are maintained so as not to exceed 200 ° C., there is no risk of temper color. The temperature of the hot rolled steel strip 2 is 80 even immediately after pickling.
Since the temperature is lower than 0 ° C, urethane or the like is conventionally used as the material of the roll that comes in contact with the steel strip 2 from the rewinder 1 to the looper 4, but the roll used for the steering device 6 arranged next to the heating device 5 is By using a nonwoven fabric with excellent heat resistance, it is possible to withstand temperatures of 80 ° C or higher and 200 ° C or lower.

The heating devices 5 and 7 may be any heating device such as an induction heating device, a direct furnace, a radiant tube burner type furnace, etc., but a gas jet for blowing a combustion gas generated from a separately provided combustion device onto a steel strip. The type heating device is more preferable because the device is simple and can easily cope with changes in the steel strip speed. In the embodiment, the heating device 7 has a small capacity of about 1/5 to 1/7 that of the large heating device 5. Further, the exhaust gas generated by the heating device 5 may be used by the small heating device 7.

FIG. 3 shows another embodiment.

This is a rolling facility in which the steering device 6 and the tension applying device 12 are arranged between the large heating device 5 and the small heating device 7. The tension applying device 12 increases the tension on the entry side of the tandem rolling mill 8 to improve the rolling property. improves. Further, since the tension of the steel strip in the heating device 5 is made low, it is possible to prevent the width reduction and the like due to the creep deformation of the steel strip during heating.
Reference numeral 14 is a steel strip speed detector, and 15a to 15d are plate thermometers provided on the inlet and outlet sides of the heating devices 5 and 7, which enable highly precise control of the steel strip temperature. 17 is its control device. Reference numeral 13 is a high temperature gas generator, and 16a and 16b are blowers for supplying high temperature gas to the heating devices 5 and 7, respectively, and the heating devices are of a gas jet type.

〔The invention's effect〕

As described above, according to the present invention, according to the processing order between the rewinding machine and the tandem rolling machine, the first heating device for heating the steel strip, the meandering prevention device for the steel strip,
Since the continuous warm rolling equipment has the second heating device arranged in sequence to raise the temperature of the steel strip lowered by cooling to the temperature before cooling, the fluctuation of the strip thickness of the strip after rolling and the strip at the time of rolling It is possible to prevent breakage and improve the yield, quality, and processing efficiency of the product strip by perfect continuous rolling. Furthermore, it is possible to use a hot-rolled steel strip that is 20 to 30% thicker than before as a raw material. Therefore, effects such as economic efficiency can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an embodiment according to the present invention, FIG. 2 is a diagram showing a relationship between a heating temperature of a steel strip and a deformation resistance, FIG. 3 is a schematic explanatory view of another embodiment, and FIG. Fig. 5 is a schematic explanatory view of a conventional cold rolling facility, and Fig. 5 is a diagram showing a pattern of steel strip speed in continuous rolling. 1a, 1b ... Rewinder, 2 ... Steel strip, 5 ... First heating device, 6 ... Meandering prevention device (steering device), 7 ...
Second heating device, 8 ... Tandem rolling mill.

Claims (1)

[Claims] 1. A rolling facility having a rewinding machine for rewinding a steel strip and a tandem rolling mill for cold rolling the rewound steel strip,
A first heating device for sequentially heating the steel strip between the rewinding machine and the tandem rolling mill according to the processing order, a meandering prevention device for the steel strip, and a temperature of the steel strip lowered by the cooling before cooling. And a second heating device capable of raising the temperature to or higher than that of the continuous warm rolling facility.