JPS6365029A - Method for controlling catenary amount of thin steel sheet for catenary type heat treatment furnace - Google Patents

Abstract

PURPOSE:To control a catenary amt. with good accuracy by detecting the catenary amt. of a thin steel sheet with a catenary sensor disposed between supporting rolls, comparing the same with the target catenary amt. and changing the rotating speed of the supporting roll. CONSTITUTION:A driving motor 5 of a bridle roll 4 of a catenary type heat treatment furnace is controlled by a speed deviation calculator 8, a PID calculator 9 and a signal selector 25, etc., from the deviation between the set value of a speed setter 7 and the value detected with a speed detector 6, by which the conveying speed of a strip W is controlled. The catenary amt. of the strip W is detected by the catenary sensor 20 disposed between the supporting roll 13 and the adjacent supporting roll (not shown) and the deviation from the set value is determined by a catenary setter 23. On the other hand, the speed change rate is determined by the PID calculator 17 from the deviation between the set value of the above-mentioned speed setter 7 and the value detected with the speed detector 15. The change rate thereof is corrected by the above-mentioned deviation value in a corrector 18 by which the driving motor 14 of the supporting roll 13 is controlled and the catenary is controlled to the target value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for processing cold rolled film in a catenary heat treatment furnace.
Regarding the method of controlling the amount of catenary when heat treating a plate (hereinafter referred to as a strip), for example, the catenary type continuous annealing furnace of continuous annealing pickling equipment in a cold rolling mill, or the catenary type paint baking of continuous coating equipment in a surface treatment factory. Applicable to control the amount of strip catenary in the furnace.

[Conventional technology]

Generally, in a catenary annealing furnace, the strip is suspended and supported in a so-called catenary shape with multiple curves by support rollers placed inside the furnace main body or near the charging port or extraction port, and the strip is continuously conveyed in this state while being conveyed inside the furnace. This is a heat treatment furnace that performs annealing treatment. In this type of furnace, it is essential for stable operation to control the catenary amount, which is the amount of hanging of the strip in the furnace, to a predetermined value.

Therefore, as a conventional method for controlling the amount of strip catenary,
For example, the method shown in Figure 2 was adopted. In Figure 1, 1 is the furnace body, 2 is a tension roll, 3 is a load cell that detects the load acting on the tension roll 2, 4 is a priddle roll, and 5 is the priddle roll. 4 is a drive motor that drives the motor 5 at a variable speed; 6 is an acceleration detector that detects the output rotational speed of the motor 5;

In this conventional furnace, the speed control of the strip W is performed as follows. The speed deviation calculator 8 calculates the deviation between the speed set by the speed setter 7 and the speed detected by the speed detector 6, and the PID calculator 9 calculates the transport speed that can eliminate the speed deviation, and drives accordingly. This is done by driving the priddle roll 4 with the motor 5.

On the other hand, in order to control the amount of catenary, the strip tension value that provides the optimum amount of catenary is determined in advance and the tension setting device is set.
The load acting on the tension roll 2 is detected by the load cell 3, and the detected load is converted into tension by the tension deviation calculator 11, and the deviation between this tension and the set tension is determined. . Then, the conveyance speed is corrected in the corrector 12 according to the tension deviation, and the priddle roll 4 is driven according to this corrected conveyance speed,
This controls the catenary amount to a predetermined amount.

As described above, in the conventional catenary amount control method, the strip tension that provides the optimum catenary amount is determined in advance, and the drive control of the prydle roll is performed using this strip tension as a target value.

[Problem that the invention seeks to solve]

However, in the method of setting a strip tension corresponding to the amount of strip catenary and controlling the tension as a target value, the tension corresponding to the amount of catenary fluctuates due to variations in the density of the strip itself, that is, fluctuations in the weight of the strip, thermal expansion of the strip, etc. Therefore, it is difficult to obtain the optimal amount of catenary in all cases. As a result, if the catenary amount is too small, the angle at which the strip is wound around the roll becomes small, causing slippage, whereas if the catenary amount is too large, the strip may come into contact with the hearth bottom, causing flaws.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for controlling the amount of catenary in a thin steel plate in a catenary heat treatment furnace, which solves the problems of the conventional method and allows the amount of catenary to be accurately controlled to a target value.

[Means for solving problems]

The present invention provides yJt! in a catenary heat treatment furnace. The four-plate catenary amount control method is characterized in that the catenary amount is detected by a catenary sensor installed between the support rolls, and the support rolls are driven at variable speed so that the detected catenary amount becomes a target catenary amount. .

Here, the support roll in the present invention includes a roll placed inside the furnace or a roll placed outside the furnace near the charging port or extraction port, and these rolls were conventionally free rolls that were not driven. .

[Effect]

In the catenary amount control method according to the present invention, the catenary amount is directly detected between the support rolls, and the support rolls are driven at variable speed so that the detected value becomes the target value, so that the above-mentioned weight fluctuation of the strip can be avoided.

Thermal expansion does not affect the amount of catenary, and the control accuracy of the amount of catenary can be improved accordingly, and as a result, the above-mentioned problem of occurrence of slip and TM due to fluctuations in the amount of catenary is solved.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a block configuration of a catenary amount control method for implementing a catenary amount control method according to an embodiment of the present invention.

In the figure, the same reference numerals as in Figure 2 indicate the same or corresponding parts, and 1
3 is a support roll that supports the strip W in the furnace; 14;
1 is a support roll drive motor that drives the support roll 13 at a variable speed, and 15 is a support roll speed detector that detects the rotational speed of the drive motor 14.

Further, 16 is a speed deviation calculator that calculates the deviation between the set speed from the speed setter 7 and the detected speed from the speed detector 15, and 17 is a PID operator that calculates a support roll speed change value that can eliminate the above speed deviation. Summer calculation unit, the calculation value is corrector 1
8. The signal is input to the support roll drive motor 14 via the hold circuit 19. Here, the corrector 18 is configured to correct the support roll speed change value according to a catenary deviation value, which will be described later.

A catenary sensor 20 is placed between the support roll 13 and an adjacent support hole (not shown) and detects the amount of catenary in the strip W. It is input to the deviation calculator 22. This catenary deviation calculator 22 is a catenary setting device 23.
The device is configured to calculate the deviation between the set catenary value and the detected catenary value from the catenary sensor 20, and output the calculated value to the corrector 18.

24 is an upper/lower limit alarm that outputs an alarm signal when the rotational speed of the support roll 130 is above the upper limit or below the lower limit; 25 is an increase/decrease pattern generator 26; PID calculator 9. This is a signal switch that switches and outputs one of the signals from the upper and lower limit alarm device 24.

Next, a case will be described in which the method of this embodiment is implemented in the catenary heat treatment furnace.

First, conveyance speed control of the strip W will be explained.

When the conveyance speed is set by the speed setter 7, the deviation between this set speed and the detected speed is determined by the speed deviation calculator 8, and the amount of speed change to make the deviation zero is determined by the PID calculator 9. The drive motor 5 accelerates and decelerates the priddle roll 4 in accordance with this speed change amount, thereby controlling the strip W to the set conveyance speed.

Next, catenary amount control will be explained.

A speed deviation calculator 16 calculates the deviation between the conveyance speed set from the speed setter 7 and the detected speed of the support roller 13, and a PID calculator 17 calculates the amount of speed change to make the deviation zero. On the other hand, the catenary amount of the strip W is detected moment by moment by the catenary sensor 20, and is inputted to the catenary deviation calculator 22 via the converter 21. The deviation from the value is calculated.

In this case, when the detected catenary value>the set catenary value, the corrector 18 corrects the speed change amount so that the rotational speed of the support roll 13 becomes faster, and the drive motor 14 rotates the support roll 13 according to this correction value. Drive at increased speed.

Further, when the detected catenary value is the set catenary value, the support roll 13 is driven to decelerate, contrary to the above. In this way, the catenary amount of the strip W is controlled to the target value.

Note that if the support roll 13 becomes faster than the predetermined upper limit speed or slower than the lower limit speed, an alarm signal is output from the upper and lower limit alarm 24, and the speed of the support roll 13 is maintained within the upper and lower limit speeds. be done.

In this embodiment, the catenary amount of the strip W is directly detected, and the support roll 1 is adjusted so that the detected value becomes the target value.
3, so even if the weight of the strip changes or the length of the strip changes due to thermal expansion, the amount of catenary will not change due to this (control accuracy can be greatly improved.

Note 1. In the above embodiment, the catenary amount is controlled only by controlling the rotational speed of the support roll 13, but it is also possible to increase or decrease the speed of the charging side priddle roll 4 so that it falls within the speed control range of the support roll 13. You can also
In this way, the catenary amount can be controlled more accurately.

Furthermore, although the above embodiments have been explained using the example of a furnace in which the support rolls are disposed inside the furnace, the present invention can of course be applied to a furnace in which the support rolls are disposed outside the furnace, and in this case,
It is desirable to configure the support roll near the extraction port outside the furnace to be able to be driven at variable speed.

Furthermore, in order to prevent slippage when the strip is wound around the support roll 13 at a small angle, the strip may be pressed by a rotatable free roll.

〔Effect of the invention〕

As described above, according to the method for controlling the catenary amount of a thin steel plate in a catenary heat treatment furnace according to the present invention, the catenary amount of the Ell plate is detected, and the support roll is driven at a variable speed so that the detected value becomes a target value. As a result, it is possible to improve the control accuracy of the catenary amount by avoiding the effects on the catenary amount due to changes in the weight of the F1114 plate and changes in length due to thermal expansion, and improve product quality by preventing slips and scratches on thin steel sheets. There is an effect that can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a catenary amount control device for carrying out a strip catenary amount control method according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional catenary amount control device. In the figure, 13 is a support roll, 20 is a catenary sensor, and W is a strip.

Claims (1)

[Claims] (1) A method for controlling the catenary amount of the thin steel sheet in the furnace to a predetermined value in a catenary heat treatment furnace in which a thin steel sheet is heat-treated while being conveyed in a state of being supported in a double curved shape by support rolls, the method comprising: The amount of catenary in the steel plate is detected by a catenary sensor arranged between support rolls, and the rotation speed of the support rolls is changed so that the amount of catenary detected by the catenary sensor becomes a target amount of catenary. A method for controlling the catenary amount of thin steel sheets in a catenary heat treatment furnace.