JPH07112210A - Winding method for hot rolled material - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for winding a hot-rolled material that does not require advanced control technology and can reliably prevent the necking of strips. [Structure] Until the strip 1 is wrapped around the mandrel 2,
The pinch roll 3 and the finishing rolling mill 5 are synchronized in rolling speed, and the winding speed of the mandrel 2 is set to be higher than the synchronous speed by a predetermined value A. After the strip 1 is wound around the mandrel 2, The mandrel 2 is decelerated and the pinch roll 3 is accelerated to synchronize them so that their speed is higher than the rolling speed by a predetermined value B. After a predetermined time passes, both speeds are synchronized with the rolling speed. take. 4 is a table roller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling a strip by hot rolling and, more particularly, to a winding method for preventing necking of the strip during winding.

[0002]

2. Description of the Related Art Necking means that an excessive impact force is generated in the strip due to the speed difference between the mandrel and the strip at the moment when the strip is wound around the mandrel, and the strip is plastically deformed to partially constrict the width of the strip. It is a phenomenon that it becomes a different shape. The mandrel is spinning at a higher speed than the strip, waiting for the strip to arrive. The reason for providing this speed difference is to improve the winding property when the tip of the strip is wound around the mandrel, and to remove the slack of the strip formed on the cooling table (usually about 100 m) from the rolling mill to the mandrel. Especially.

As a conventional technique, an intermediate pinch roll is installed on a table, the line speed of the strip is detected, and the speed of the mandrel and the pinch roll is made higher than the line speed in accordance with this line speed. To have an appropriate lead rate, the strip is wound around the mandrel and the speed of the pinch roll is reduced at the same time (Japanese Patent Laid-Open No. 2-235517), or two pinch rolls are installed and the pinch roll There is disclosed a method (Japanese Patent Laid-Open No. 2-151315) in which the speed is reduced before the strip passes around the mandrel and the excessive tension at the time of winding is provided as the back tension of the pinch roll. .

[0004]

In all of the above-mentioned prior arts, (a) the pinch roll is provided with a lead rate to remove the slack of the strip, and thereafter (b) an excessive impact force is not generated on the strip. As described above, the two-stage process of reducing the speed of the pinch roll is performed before the completion of winding.

However, in reality, the above two processes need to be performed within a very short time. For example, Japanese Patent Laid-Open No.
As in Japanese Patent Publication No. 235517, the time during which the tip of the strip reaches the mandrel and the tension is generated is generally considered to be the time until the strip is wound a couple of times, but this is 0.5 seconds. It is the following phenomenon. Further, considering that the pinch roll is decelerated after passing through the pinch roll and before being wrapped around the mandrel as in Japanese Patent Laid-Open No. 2-151315, this distance is usually about 10 m, and the passing speed is 700 mpm. For example, the passing time difference is 0.86 seconds.

In any of the above-mentioned publications, it is necessary to decelerate the pinch roll within this short time, but the lead rate of the pinch roll is 10%, the strip passing speed is 700 mpm, and the deceleration rate is 40 mpm / sec. Calculated using normal values, the time required to return the lead rate to zero is 1.8.
It becomes seconds, and it can be seen that the processing is not completed within the time allowed for the above control. As described above, when the conventional technique is applied to the actual operation, it is necessary to accurately control the timing in a very short time and control with a deceleration rate of about 2 to 3 times that of the normal operation. It can be seen that advanced control technology is required. Therefore, this prior art is a highly dangerous method because there is a high probability that winding failure will occur if the control timing is incorrect.

The present invention does not require sophisticated control techniques,
An object of the present invention is to provide a method for winding a hot-rolled material that reliably prevents necking.

[0008]

According to the present invention, when a strip rolled by a hot rolling mill is wound on a mandrel via a pinch roll, the pinch roll strip is conveyed until the end of the strip is wound on the mandrel. The speed is synchronized with the strip rolling speed, and the winding speed of the mandrel is set to be higher than the synchronous speed by a predetermined value A. After the strip is wound around the mandrel,
The winding speed of the mandrel is reduced and the strip conveying speed of the pinch roll is accelerated so that both speeds are synchronized to be higher than the rolling speed by a predetermined value B, and after the predetermined time passes, the both speeds are rolled. A method for winding a hot-rolled material is characterized in that the material is wound in synchronism with the speed.

[0009]

In the beginning of winding the strip on the mandrel, the mandrel is rotated at a speed higher than the rolling speed of the strip, so that the strip is wound and tightened while slipping between the strip and the mandrel. At this time, the mandrel lead rate required is smaller than the lead rate required for strip slack removal. In the present invention, as shown in FIG. 1 (a), the above-mentioned good winding property is secured by providing a speed difference between the pinch roll and the mandrel while leaving the slack of the strip on the table. Is.

Then, when the winding is completed, the mandrel is decelerated and the pinch rolls are accelerated to synchronize the speeds of the two so that the strip between the pinch rolls and the rolling mill is not slackened. To have a lead rate. As a result, as shown in FIG.
The slack of the strip on the table can be removed and stable rolling can be performed. The lead rate used for removing the slack is set to a small value to prevent the impact force from being generated on the plate when the slack is removed, and the slack is removed over time. In the present invention, it is not necessary to take up slack in a short time as in the prior art and to wind the slack, so that the lead ratio with respect to the rolling speed of the pinch roll can be made small and necking can be prevented.

That is, in the prior art, the three operations of strip slackening, deceleration, and winding were switched within a very short period of time, whereas the present invention first carries out winding firmly. The slack of the strip is gradually removed later to prevent the generation of impact force, thereby preventing the occurrence of necking.

[0012]

EXAMPLES Examples of the present invention are shown below. This example was carried out in a strip hot rolling line, and the lead ratio before the strip was wound on the mandrel was 5% mandrel and 0% pinch roll, and after winding, 1% mandrel and 1% pinch roll. Was carried out as. The strip is a soft material with a thickness of 3 mm and a width of 1000 mm.
According to the present invention, the necking occurrence amount becomes zero, while the necking of about 7 mm to 7 mm occurs.

It has been confirmed that even if the lead rate of the mandrel before winding the strip is changed in the range of 10% to 1%, the necking is effectively prevented. 1
When the lead ratio is 0% or more, the impact force generated when the strip is wound around the mandrel becomes excessive, propagates over the pinch roll to the table, and exhibits unstable behavior. Further, when the lead ratio was lowered to 1% or less, the winding property around the mandrel was deteriorated.

In this embodiment, the pinch roll is the mandrel 1
Although one set is provided for the base, it is more effective to combine with two sets of pinch rolls as in the above-mentioned JP-A-2-151315 in order to enhance the effect of blocking impact force. That is, even if a material that is thinner than the strip used in this embodiment and is easy to neck is applied to the present invention, necking can be prevented.

FIG. 2 is a time chart of the speed control of the present invention.
Shown in. Mandrel winding of the strip is detected by the rising signal of the load current value of the mandrel motor. Based on this detection signal, change the mandrel speed from 5% to 1%
At the same time, the pinch roll speed is set to 0
Accelerate from 1% to 1% to remove any slack in the strip on the table.

In this embodiment, it is not judged whether the slack of the strip has been removed. Instead, the speed of the mandrel and the pinch roll is synchronized with the speed of the strip after the speed is maintained for 3 seconds by the timer. (This is because it is empirically known that the slack of the plate on the table is removed in about 3 seconds. This time varies slightly depending on the production line, but empirically for a specific line. Can be asked).

[0017]

According to the present invention, the lead ratio of the mandrel speed to the rolling speed required for improving the winding property of the strip on the mandrel and the mandrel and the pinch required to remove the slack of the strip on the table. Separately consider the lead rate against the rolling speed of the roll speed, add the lead rate to obtain good wrapping property only to the mandrel until the strip is wound, and synchronize the mandrel and pinch roll after winding is completed. When the tape is rolled against the rolling speed, it is possible to remove the slack of the strip with a small lead rate (slowly over time), which has high certainty, and does not require exceptionally high control to prevent necking. It has an excellent effect.

Further, in the present invention, since the slack of the strip remains on the table when the strip is wound around the mandrel, even if the impact force of the winding cannot be completely blocked by the pinch rolls, the slack is enough. It was also found that the effect of absorbing the impact and preventing necking can be obtained.

[Brief description of drawings]

1 is an explanatory view of the operation of the present invention, FIG. 1 (a) shows a slack state of a strip on a line when the strip is wound around a mandrel, and FIG. 1 (b) is FIG. 1 (a).
Next, the state of eliminating the slack of the strip on the line when the mandrel and the pinch roll are synchronously operated is shown.

FIG. 2 is a time chart of speed control of the mandrel and pinch roll of the present invention.

[Explanation of symbols]

 1 strip 2 mandrel 3 pinch roll (upper and lower) 4 table roller 5 finishing rolling mill

Claims (1)

[Claims] 1. When winding a strip rolled by a hot rolling mill onto a mandrel via a pinch roll, the pinch roll strip conveying speed is synchronized with the strip rolling speed until the end of the strip is wound around the mandrel. The winding speed of the mandrel is set to be higher than the synchronous speed by a predetermined value A, and after the strip is wound around the mandrel, the winding speed of the mandrel is reduced and the strip conveying speed of the pinch roll is set. And the speed of both is synchronized so that the speed of the both is higher than the rolling speed by a predetermined value B, and after passing a predetermined time, the speed of both is synchronized with the rolling speed and winding is performed. Winding method of material.