JPH044913A - Method for preventing tail end jumping up on continuous rolling mill - Google Patents

Abstract

PURPOSE:To prevent the meandering of the material to be rolled by decreasing the tension in the specific stand and the next stand before passing the tail end of the material to be rolled through the concerned stand, calculating the change of rolling load from the model equation of rolling load, deducting the gap correcting quantity due to the quantity of load change from the gap quantity of the plate thickness controlling. CONSTITUTION:The rolling is executed while tracking with the tracking device 9. When the tail end part of the material to be rolled is reaches the distance detected with the sensor 10 positioned at front of the i-th stand among the tandem stands or reaches the distance estimated with tracking, the tension of the material to be rolled is reduced with the tension reduction controlling device 8 between the i-th stand and the (i+1)th stand positioned in front of the above. In this stage, the change of the load caused by the tension change of the i-th stand and the load change of the (i+1)th stand is calculated by utilizing the rolling model and the correcting quantity of gap caused only with the tension change is calculated from these load change and it is deducted from the correcting quantity of the plate thickness controlling device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a technology for preventing the tail end of a strip-shaped metal material from splattering during continuous hot rolling of a steel plate or the like.

[Conventional technology]

During strip rolling, when the strip passes through the stand, the tension at the tail end of the strip momentarily becomes zero, so it bounces off and hits the side guide, causing the end to fold or
If the shape of the tail end is poor, the tail end may tear and cause flaws on the roll surface, which may require roll replacement.

As a countermeasure, a method has been proposed in JP-A-53-10353 in which the tension between the stands is reduced to prevent the ends from bouncing off when lowering the louver angle, but the control method using the looper is Since the control system adjusts the angle of the tail end of the material fed from the front stand to the rear stand, and the angle and tension interfere with each other, a phenomenon occurs where the tension does not drop as much as intended.

Further, Japanese Patent Laid-Open No. 57-32814 proposes a method in which the speed of the forward rolling mill is lowered at the tail end of the material to loosen the tension between the stands.

However, with this method, the tension is loosened, which increases the load on the rolling mill, tightens the gap with AGC (automatic plate thickness control), and conversely tends to cause meandering.

[Problem to be solved by the invention]

The looper is a control system in which the angle and tension interfere with each other, so if you lower the angle preferentially at the tail end of the material, the tension will not decrease, and if you try to lower the tension preferentially at the tail end of the material. Then, a problem arises in that the feed angle is not lowered sufficiently, causing material to splatter.

Furthermore, if you try to lower the tension in advance or lower the tension at the tail end as a countermeasure, the rolling load will increase and the plate thickness control device will tighten the gap, causing the tail end of the material to meander.
In addition, there is a problem in that the material folds against the side guides, similar to when the tail end of the material snaps off, causing flaws in the roll.

The problem to be solved by the present invention is to find a means for preventing meandering of a rolled material in preventing the tail end of the rolled material from splashing in a tension control system using a looper in a tandem rolling mill.

[Means to solve the problem]

When the present invention detects the passing of the tail end of a material to be rolled at a position in front of a specific stand of a tandem rolling mill, the tension in the stand and the next stand is reduced before the tail end passes the specific stand, and the tension is reduced in the stand and the next stand. The above problem was solved by calculating the rolling load change due to tension reduction from the rolling load model formula, and then subtracting the gap correction amount due to the load change from the gap amount for plate thickness control.

The above-mentioned passage of the tail end of the material to be rolled can be directly detected by a sensor, or it is also possible to employ a detection means based on calculations based on the circumferential speed of the roll, etc.

[Effect]

In order to prevent the tail end of the material from springing off by loosening the tension between the stands, the tightening of the roll gap due to the decrease in tension can be subtracted from the amount of correction of boyar for plate thickness control (this can be prevented, and the meandering of the material to be rolled can be prevented). will not occur.

〔Example〕

FIG. 1 is a schematic diagram in which the present invention is applied to a tandem rolling mill. In the figure, 1 is a rolling mill, 2 is a hydraulic rolling device, and 3 is a rolling mill.
is a looper, 4 is a material to be rolled, 5 is a looper control lid, 6
Reference numeral denotes a sheet thickness control device, 7 a gap correction correction device, 8 a tension reduction control device, 9 a tracking device, and 10 a sensor for detecting the tail end of sheet threading.

During the rolling operation, rolling is performed while being tracked by the tracking device 9. When the tail end of the material to be rolled reaches the distance estimated by detection or tracking by the sensor 10 located in front of the first stand in the tandem stand, it is located in front of the first stand. The tension of the material to be rolled is decreased by the tension reduction control device 8 between the 1st and 1st times. At this stage, the rolling model is used to calculate the load variation at one stand due to the tension reduction and the load variation at i+1 stand.
This method calculates the amount of gap correction due to only the tension variation from the load variation, and subtracts it from the correction amount of the plate thickness control device.

〔Effect of the invention〕

The present invention can achieve the following effects.

(1) Meandering of the material to be rolled does not occur, and the function of preventing tail end splashing by the looper can be fully demonstrated.

(2) Therefore, the occurrence of damage to rolls, etc. due to tail end splashing is reduced.

(3) Since it is possible to reduce the number of roll replacements due to damage to rolls, etc., an improvement in work efficiency can be expected.

(4) The impact on other products due to irregular roll changes can be reduced, and the number of outside orders can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a control system for implementing the present invention. 1: Rolling machine 2: Hydraulic rolling device 3 Nil-par 4: Rolled material 5 Nil-par control device 6: Thickness control device 7: Gap correction device 8: Tension reduction control device 9 Ni-dracking device 10: Sensor patent Applicant New Japan! i! Masu Kobori, Representative of the Steel Stock Company

Claims (1)

[Claims] 1. In a tandem rolling machine equipped with a measuring device that measures the load and thickness of the material to be rolled, a rolling control device that controls the thickness of the material to be rolled to a target value, and a control device that controls the tension between the stands to be constant, When the passage of the tail end of the material to be rolled at the front position of a specific stand is detected, the tension in that stand and the next stand is reduced before the tail end passes through the specific stand, and the rolling load change due to the decrease in tension is reduced. A method for preventing tail end splashing of a continuous rolling mill, characterized by calculating from a load model formula and further subtracting a gap correction amount based on the load change from a gap amount for plate thickness control.