JP3389785B2 - Metal strip tension control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the tension of a metal strip in a continuous heat treatment furnace for a metal strip.

[0002]

2. Description of the Related Art In a continuous heat treatment equipment for a metal strip such as a continuous annealing furnace, the temperature of the metal strip in the furnace may rise and break when the metal strip is stopped (at the time of traveling stop). this is,
Since the strength of the metal strip is lowered by the temperature rise, the metal strip is broken by the tension applied to the metal strip.
The tension of the metal band is given for the stability of running.

Therefore, conventionally, a method of reducing the tension of the metal strip when the metal strip is stopped has been proposed. For example,
Japanese Unexamined Patent Publication (Kokai) No. 60-82620 describes a technique of controlling the tension of a metal strip in a furnace using a dancer roll. In this technique, the tension of the metal strip in the furnace is lowered by increasing the feeding amount of the metal strip into the furnace before stopping the traveling of the metal strip.

In this technique, when the traveling speed of the metal strip falls below a predetermined level, a heating zone compensation signal is generated and the tension of the metal strip in the furnace using the dancer roll is controlled.
This heating zone compensation signal continues until the running speed of the metal strip becomes 0, that is, until the metal strip stops. During this period, the amount of the metal strip fed into the furnace is made larger than usual so that the tension finally becomes zero.

[0005]

However, in the above-mentioned technique (prior art), the tension during the period until the metal strip stops can be suppressed, but the control thereafter is not considered. In fact, in the heat treatment furnace, the temperature inside the furnace gradually drops while the metal strip is stopped because of its large thermal inertia. Along with that, the temperature of the metal strip in the furnace is also lowered and the metal strip tries to shrink, but it is constrained because the heat treatment equipment is stopped and cannot shrink. as a result,
The tension of the metal strip gradually increases. Eventually, the problem of the metal strips trying to shrink rupturing in the furnace remained unsolved.

[0006] As a countermeasure against such a case, the equipment operator performs an operation to loosen the tension, predicts the amount of shrinkage of the metal strip when the equipment is stopped, and puts the metal strip into the furnace (before leaving the site). It was also sent in advance. However, such an operation is uncertain, and a secondary abnormality such as breakage due to insufficient feeding of the metal strip or deterioration of shape due to excessive feeding occurs.

The present invention provides a method for solving the above-mentioned problems, and a method for preventing the metal strip from breaking or its shape deteriorating in the furnace even after the operation of the equipment is stopped.

[0008]

According to a first aspect of the present invention, in a method for controlling tension of a metal strip in a continuous heat treatment furnace for continuously heating a metal strip, the heating of the metal strip is stopped and the operation of the equipment is stopped. A method for controlling the tension of a metal strip, characterized in that the tension of the metal strip is measured, and the tension is controlled by feeding the metal strip into a furnace so that the measured value has a preset tension. Is.

In the present invention, the preset tension is a tension set from the viewpoint of operation and quality. Although the value of the tension varies depending on the specifications of the equipment and the like, the value of the tension should be at least such that the metal strip is not broken and the shape is not deteriorated. Actually, it is decided by looking at safety from past operation data. Even after the operation of the equipment is stopped, the metal strip
Measure the tension of the
Tension control is performed by feeding the metal strip into the furnace.

According to the second aspect of the present invention, the amount of the metal strip fed into the furnace after the operation of the equipment is stopped is measured, and the measured value of the fed amount is the upper limit value of the feed amount determined based on the temperature of the metal strip. The metal strip tension control method according to claim 1, wherein tension control of the metal strip is performed within a range not exceeding the above.

In the present invention, the feed amount is measured and compared with the feed amount upper limit value. The upper limit of the feeding amount is the metal strip
It can be calculated from operating conditions based on the temperature .
When the measured value of the feed amount exceeds the feed amount upper limit value, the feeding of the metal strip is stopped by a measure such as stopping the tension control. In this way, the feed rate depends on the metal band temperature.
By providing an upper limit value based on, prevents free write sends an excessive metal strip in the furnace, the shape deterioration of the metal strip is prevented.

[0012]

1 is a block diagram showing an example of an embodiment of the present invention. In this figure, 1 is a metal strip, 2
Is a transfer roll, 3 is a tension switching point, 4 is an inlet combustion zone, 5 is an outlet combustion zone, 6 is a tension meter, 7 is a measuring roll, 8 is a feed amount measuring device, and 9 is a feed amount upper limit calculator. 10 is a comparator, 11 is a tension control calculation unit,
Reference numeral 12 is a set tension when the metal strip is stopped, 13 is a limiter of the tension control output, and 14 is a metal strip temperature. The subscripts 6 to 13 in the figure indicate that the subscript a is a code relating to the inlet combustion zone and the subscript b is a code relating to the outlet combustion zone.

Here, the tension switching point 3 is a point at which the feeding direction of the metal strip is switched, and the entrance side is called the entrance side combustion zone 4 and the exit side is called the exit side combustion zone 5. In the inlet combustion zone 4, the transport roll 2 is controlled to rotate in the normal direction to have the set tension 12a, and in the outlet combustion zone 5, the transport roll 2 is controlled to rotate in the reverse direction to have the set tension 12b.

The feeding amount is measured rolls 7a,
7b, and this is detected by the feed amount measuring devices 8a, 8
Convert the amount into the feeding amount in b and use it as the measured value. The measured values of the feeding amount are compared with the feeding amount upper limit value by the comparators 10a and 10b. The upper limit value of the feed amount is calculated by the feed amount upper limit calculators 9a and 9b using the metal band temperature 14, the size of the metal band, and the like. When the measured feed amount exceeds the feed amount upper limit value, the tension control calculation unit 11
The feeding of the metal strip is stopped by a measure such as stopping the calculation of a and 11b.

Here, the metal strip temperature may be constantly measured, but the heating temperature of the metal strip may be used. The metal strip tension control according to claim 1, wherein the method controls the tension of the metal strip by setting an upper limit value of the amount of the metal strip fed into the furnace by using the heating temperature of the metal strip. It can be called a method.

It should be noted that instead of setting an upper limit on the feeding amount of the metal strip, an upper limit may be set on the execution time of the tension control.
This method is characterized by monitoring the execution time of the tension control of the metal strip after stopping the operation of the equipment, and performing the tension control of the metal strip within the range where this execution time does not exceed the preset upper limit value. The metal strip tension control method according to claim 1 can be said.

The limiters 13a and 13b are provided to keep the tension control output of the tension control calculation units 11a and 11b within a certain range. The limiter 13a in the inlet combustion zone outputs only + side output, and the limiter 13b in the outlet side combustion zone outputs only-side output. In this way, even if there is some malfunction, the metal strip moves toward the feeding side, so that at least breaking of the metal strip can be avoided.

[0018]

EFFECTS OF THE INVENTION The metal strip tension control method according to the present invention can cope with a change in tension over a long period of time while the equipment is stopped, and the metal strip may be broken due to insufficient feeding or the shape may be deteriorated due to excessive feeding. Secondary abnormalities can be prevented.

In addition, it is possible to automate the corresponding treatment by a human-sensible operation.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an embodiment of the present invention.

[Explanation of symbols]

1 metal strip 2 Conveyor roll 3 Tension switching points 4 Entry side combustion zone 5 Outgoing combustion zone 6 Tensiometer 7 Measuring roll 8 Feed rate measuring device 9 Feeding amount upper limit value calculator 10 Comparator 11 Tension control calculator 12 Set tension when metal strip is stopped 13 Tension control output limiter 14 Metal band temperature Subscript a Symbol for entry side combustion zone Subscript b Symbol for exit side combustion zone

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-2-125818 (JP, A) JP-A-2-125819 (JP, A) JP-A-5-295450 (JP, A) JP-A-5- 70844 (JP, A) JP 62-77424 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21D 9/56 101 C21D 11/00 105 C21D 9/52

Claims (2)

(57) [Claims] 1. A metal strip tension control method for a continuous heat treatment furnace for continuously heating a metal strip, wherein the tension of the metal strip is measured after the heating of the metal strip and the operation of the equipment are stopped.
Tension and control the tension by sending a metal strip into the furnace so that the measured value is the preset tension.
A method for controlling tension of a metal strip, which is characterized in that: 2. The feeding amount of the metal strip into the furnace after the operation of the equipment is stopped, and the measured feeding amount is the metal strip.
The metal strip tension control method according to claim 1, wherein tension control of the metal strip is performed within a range not exceeding an upper limit value of the feed amount determined based on the temperature .