JPS61249624A - Tension controlling method for payoff reel - Google Patents

Abstract

PURPOSE:To prevent the flaw around a tail end of a strip and to increase the yield by limitting the strip tension at an ordinary time and the time of the coil remaining thickness reaching a limitation set value in case of rewinding a coil from a payoff reel. CONSTITUTION:The tension of a strip 12 is controlled so as to make 0.35-0.8kg/mm<2> at the ordinary time. The tension of the strip 12 is also controlled so as to reduce to 0.15-0.30kg/mm<2> at the time of the coil remaining winding thickness of the payoff reel 10 reaching 2-50mm set value. The reason for the limitation of the tension and coil remaining winding thickness is because of the bounding phenomenon being of no problem since the acceleration is not possible but only ordinary speed reduction in case of <=50mm. However, in case of the tension becomes <=0.15kg/mm even in case of <=50mm coil thickness the control of the payoff reel 10 becomes unstable and it is feared that the strip becomes in a loop shape and the tension is therefore limitted.

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention relates to a method for controlling the tension of a payoff reel, and in particular, a coil suitable for controlling the tension of a payoff reel in a reverse or tandem cold rolling mill. This invention relates to an improvement in a method for controlling the tension of a payoff reel when unwinding from the payoff reel. 2. Description of the Related Art Generally, when a plate after pickling is cold rolled, the tension of the payoff reel is considered to be approximately 0.35 to 1.4 kg/l. This is because the tension of the tension reel in a normal pickling line is 0.8
While it is operated at around 1.6 kg/- (varies depending on the line), if the tension of the payoff reel of the cold rolling mill, which is the next process, is higher than this, so-called tightening will occur. On the other hand, if the tension on the payoff reel is too weak, the loose strip may suddenly tighten when the line accelerates.
On the other hand, this is because when the line decelerates, the deceleration of the payoff reel coil is delayed, which is a so-called coil bouncing phenomenon. In particular, winding tightening is likely to occur after the remaining winding thickness of the coil becomes small. 0.30~0.50k from .4m/vl
A method of weakening it to g/- has been proposed. This method is characterized in that the payoff reel tension is normally increased in order to maximize the tension on the entry side of the first stand of the rolling mill, which is disposed on the payoff reel exit side. However, as shown in FIG. 5, the strips 12 rewound from the payoff reel 10 are sequentially welded by the welding machine 14 on the entry side, and during this time the strips stored in the louvers 18 provided between the pre-roll rolls 16 are welded. In a completely continuous rolling mill in which rolling is continued without interruption in the cold rolling mill 20 by continuously unloading the rolling stock 12, the priddle roll 16 is installed on the entrance side of the cold rolling mill 20. , it is possible to increase the tension on the first stand entry side without increasing the tension on the payoff reel 1o. In FIG. 5, 22 is a cutting device, and 24 is a tension reel. Moreover, even if it is a batch type rolling mill as shown in Fig. 6,
The same applies if the priddle roll 16 is installed on the entrance side of the cold rolling mill 20. Therefore, in order to prevent the coil from bouncing during tightening and acceleration/deceleration, the tension of the payoff reel is set to 0.35 throughout the entire area.
It is conceivable to operate under control to a level of ~0.8 kg/w.

Problems to be Solved by the Invention] However, as a result of the inventor's investigation, even if the tension of the payoff reel is controlled to 0.35 to 0.8 kg/- over the entire area, the problem occurs near the tail end of the strip. It was found that there were defects. This flaw is a particular problem in a fully continuous rolling mill where the entire length is on-gauge because it hinders yield improvement. OBJECTS OF THE INVENTION The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a tension control method for a payoff reel that can reliably prevent flaws near the tail end of the strip. shall be.

[Means to solve the problem]

As shown in FIG. 1, the present invention normally controls the tension of the strip to be 0.35 to 0.8 kg/d when unwinding the coil from the payoff reel. When the remaining winding thickness of the coil reaches the set value within 2 to 50 nm, the tension of the strip is increased to 0.15 to 0.
The above objective was achieved by controlling the velocity to be weakened to 30 m/-.

[Effect]

The inventor investigated the cause of the flaw near the tail end of the strip, and found that the flaw was caused by the edge 12A of the blade when dividing the strip 12 on the pickling line, as shown in FIG. As shown in Figure 3, the innermost winding is payoff reel 10.
It has been found that this occurs by rubbing the adjacent strips 12 at the moment of separation. In order to prevent strip flaws caused by this blade burr 12A, the best way is to prevent the blade burr 12A itself from occurring using the pickling line's dividing device, but it is not always perfect, so there are some It is desirable to adopt a tension control method for the payoff reel that does not cause flaws even if the blade is burred. For this reason, the inventor investigated the degree of flaws caused by the edge 12A by varying the tension of the payoff reel, and found that the payoff reel tension for several turns at the tail end was 0.30k.
It has been found that flaws can be significantly reduced if the ratio is less than g/i-. This is because the last volume expands as shown in Figure 4. It is presumed that this is because the blade of the knob 12 is not easily affected by the collar 12A.In reality, it is difficult to change the tension with only a few turns remaining from the viewpoint of control accuracy, so the remaining windings of the coil are difficult to change. It is practical to lower the tension when the thickness reaches an appropriate thickness of 50n or less.Here, the reason why the thickness is 50n or less is that below this remaining winding thickness, there is usually only deceleration and no acceleration. However, even if the winding thickness is 50 nm or less, if the tension of the payoff reel becomes an extremely low tension of 0.15 kg/- or less, the control of the payoff reel 10 will become unstable. , there is a risk that the strip 12 may become looped during deceleration.For this reason, even if the remaining winding thickness is 50n or less, the thickness of the strip 12 is 0.15 to 0.3
A suitable tension is 51 cg/-. The present invention has been made based on the above findings.

【Example】

When the payoff reel 10 of a completely continuous rolling mill similar to the conventional example shown in FIG. Although it suffered from scratches due to
When the remaining winding thickness of the coil is 401m or less,
By switching to 0% tension, that is, 0.28 b/wd, it was possible to prevent flaws and improve yield without making control unstable.

【Effect of the invention】

As explained above, according to the present invention, it is possible to reliably prevent flaws in the strip due to the edge of the blades, and in particular, it has the excellent effect of improving the yield of a fully continuous rolling mill.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the gist of the payoff reel tension control method according to the present invention, and Fig. 2 shows the shape of the vicinity of the tail end of the strip where the blade has a burr, in order to explain the present invention in detail. The side view, FIG. 3, is a side view showing the unwinding state near the tail end of the strip when the tension is high, and FIG.
Similarly, FIG. 5 is a side view showing the unwinding state near the tail end of the strip when the tension is low. FIG. 5 is a side view showing an example of the configuration of a conventional fully continuous rolling mill. FIG. FIG. 2 is a side view showing a configuration example of a batch-type rolling mill equipped on the entry side. 10...Payoff reel, 12...Strip.

Claims (1)

[Claims] (1) When unwinding the coil from the payoff reel, the tension of the strip is usually 0.35 to 0.8 kg/
When the remaining coil thickness of the payoff reel reaches a set value of 2 to 50 mm, the strip tension is adjusted to 0.15 to 0.2 mm.
A method for controlling the tension of a payoff reel, characterized in that the tension is controlled to be weakened to 30 kg/mm^2 to prevent flaws in the strip.