JPH07118761A - Method for controlling tension in continuous annealing furnace and device therefor - Google Patents

Abstract

PURPOSE:To suitably control the tension of a steel strip in each of zones without mutual interference by controlling voltage of each of motors for driving helper rolls in a heating zone, soaking zone and cooling zone by a specific method, at the time of annealing the steel strip in a continuous annealing furnace. CONSTITUTION:The steel strip 9 is annealed by passing through each block 2 of the heating zone 2a, soaking zone 2b and cooling zone 2c in the continuous annealing furnace 1. The tension of the steel strip 9 in the blocks 2a-2c is suitably controlled according to the kind of steel, strip thickness, strip width, etc., of the steel strip 9 to be annealed, and the steel strip 9 is stably passed through each block 2a-2c in the continuous annealing furnace 1. For this purpose, the variating allowance SV of the control voltage of each of the driving motors M of the helper rolls 3 for carrying the steel strip in each block 2a-2c is obtd. by deltaV=A<-1>deltaF (wherein, A: constant) from the deviation deltaF between the setting value of the tension and the measured value in each block 2a-2c. The motor M for driving the helper rolls in each block is controlled with this deltaV and the tension of the steel strip in each block 2a-2c is suitably controlled without interference and independently, thus, even if the kind of the steel strip 9 to be annealed is changed, the stable continuous annealing can be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace tension control method and apparatus in a continuous annealing furnace process line in which strips are conveyed by a large number of helper rolls.
More specifically, the present invention relates to a furnace tension control method and device that can control the tension of each block of a continuous annealing furnace in accordance with the strip thickness, width, steel type, and the like, and can control the tension with high response.

[0002]

2. Description of the Related Art In a conventional strip annealing process line, a continuous annealing furnace is divided into blocks having different processing temperatures such as a first heating zone, a second heating zone, a soaking zone, an annealing zone, and a quenching zone. Then, heat treatment is carried out while being transported by a helper roll or the like in each block. Generally, in order to pass the strip stably, it is better to make the tension as high as possible. However, the strip in the continuous annealing furnace is at a high temperature, and if the tension is increased too much, drawing will occur and in the worst case, it will break. Therefore, taking into consideration the strip squeezing prevention and the sheet passing property, for example, the tension of the strip is decreased in the high temperature portion and increased in the low temperature portion, and the tension of the strip in each block is changed to stably convey the strip. It is devised so that. In this case,
When strips of different width and thickness are processed in the same continuous annealing furnace, the tension in each block must be reset each time. Particularly in recent years, due to market demand, thinning and widening of strips and softening have facilitated squeezing in the furnace, while strips that are easy to squeeze in the furnace are passed through at high speed in order to pursue high productivity. It is necessary, and the tension set as a means for that is high response,
Moreover, tension control that is stably realized is essential.

As a conventional strip tension control method for each block in this type of process line, as a non-interference control method in which the result of controlling the tension in one block does not affect other blocks, for example, JP-A-58-58 The method disclosed in 110620 or JP-A-62-263933 is known.

That is, in the method disclosed in Japanese Patent Laid-Open No. 58-110620, mutual influence between blocks is prevented by applying a tension control signal to other blocks upstream or downstream to perform a successive control. It is a thing. Further, the method disclosed in Japanese Patent Laid-Open No. 62-263933 considers not only the concept of tension control for each block but the effect of each block on the overall tension in the furnace. Adjust the tension setting of the constant tension control device (current-controlled tension applying device such as bridle roll or dancer roll) installed at one end on the downstream side to adjust the overall tension level of the process line and Formulate the influence of the voltage operation of the hearth roll motor of the block on the tension of each part of the relevant process line based on the characteristics of the motor, and use this formula to generate the decoupling control output that does not affect the tension of blocks other than the block to be controlled. It is what you want.

[0005]

In the former method of performing the above-mentioned successful control, when the control outputs to be fed back between the blocks have opposite polarities of the tension control outputs between the adjacent blocks, the control outputs to the control outputs are reversed. It may cause a disturbance and increase the tension deviation on the contrary, they may interfere with each other,
There is a problem of low stability.

Further, the latter method has a problem that it cannot be applied to an apparatus in which one of the inlet and outlet of the continuous furnace is controlled in a constant speed because the tension is controlled in a constant manner.

In recent years, in particular, due to market demand, the strips produced in process lines such as continuous annealing furnaces are rapidly becoming thinner and wider (for example, widths of 600 to 12).
With a thickness of about 50 mm and a thickness of about 0.15 mm), there is a problem that the conventional method cannot secure a stable strip passing plate.

The present invention solves such a problem and surely realizes the optimum tension for each block even when the tension is changed by different materials, and moreover, the thin and wide strip can be surely conveyed. An object of the present invention is to provide a furnace tension control method and apparatus for a continuous annealing furnace.

[0009]

SUMMARY OF THE INVENTION An internal furnace tension control method for a continuous annealing furnace according to the present invention is an annealing furnace composed of a plurality of blocks, and a helper roll for carrying a strip provided inside each of the plurality of blocks. A constant speed controller and a constant tension controller for the strip, which are respectively provided on one and the other of the inlet side and the outlet side of the set of the plurality of blocks, and the strip in each block that drives the helper roll. A method for controlling the tension of each block in a continuous annealing furnace consisting of a drive motor that holds the tension of each of them constant, and each method for controlling the tension of each block to a target value. δV increases and decreases cost δV control voltage of the drive motor of the block by the deviation .delta.F of readings with tension set values of the respective blocks = a ^-1 .delta.F where a is the drive motor And constants and formulated determined by the rating of the motor, is characterized in that to control the tension of independently in each block for each block without interfering with other blocks from said relational expression.

Further, the in-furnace tension control device for a continuous annealing furnace according to the present invention comprises an annealing furnace composed of a plurality of blocks, a helper roll for carrying a strip provided inside each of the plurality of blocks, and A constant speed control device and a constant tension control device for the strip, which are respectively provided on one and the other of the inlet side and the outlet side of the set of blocks,
A furnace tension control device for a continuous annealing furnace, which controls the tension of each block in a continuous annealing furnace, comprising: a drive motor that drives the helper roll and holds the tension of the strip constant in each block. a) means for obtaining a difference in set tension and difference in measured tension between the inlet side and outlet side of each of the blocks, and (b) means for obtaining a deviation δF between the set tension difference and the measured tension difference, c) Means for obtaining the control operation amount δV for controlling the drive motor of the helper roll by the deviation δF of the tension by the following equation: δV = A ⁻¹ δF, where A is a constant determined by the rating of the drive motor (d) And a means for controlling the drive motor by the control operation amount δV.

[0011]

According to the present invention, the deviation δF _i (ΔS _{i-1 i} −ΔT _{i-1 i} ) of the difference ΔT _{i-1 i} of the actual tension values from the difference ΔS _{i-1 i} of the tension target values of the adjacent blocks. For each block, and the increase / decrease amount δ of the control voltage of the drive motor of each block for controlling the tension of each block to a target value.
V is defined by the deviation δF between the set value of the tension of each block and the measured value δV = A ⁻¹ δF, where A is formulated as a constant determined by the rating of the drive motor, and each relation is expressed without interference with other blocks. Since the operation control amount of the drive motor that independently controls the tension in each block is obtained for each block, the voltage correction signal of the drive voltage, that is, the tension control output of each block does not interfere with each other. As a result, the set tension in each block can be stably realized with high response.

[0012]

EXAMPLES Next, the method for controlling the internal tension of the continuous annealing furnace of the present invention will be described with reference to the drawings. 1 is a flow chart showing the control method of the present invention, FIG. 2 is a schematic diagram in which a strip is modeled as an elastic body for each annealing furnace composed of blocks for explaining the control method of the present invention, and FIG. 3 is the present invention. FIG. 3 is a schematic diagram of an example of a strip tension control device in a continuous annealing furnace consisting of three blocks for explaining the control method of FIG.

In FIG. 3, reference numeral 1 denotes a continuous annealing furnace, and this embodiment shows an example of three blocks for simplicity.
The inside of each block 2 can be controlled at different temperatures, and the strip 9 can be conveyed in each block 2 (2a, 2b, 2c) by a plurality of helper rolls 3 in the furnace. Has been At the inlet side of the continuous annealing furnace 1, a constant tension control device 4 for the strip 9 consisting of an inlet side bridle roll is provided, and the tension of the inlet side strip 9 is set to a set value by an automatic current controller ACR via a tension current converter. It is supposed to be. Further, the constant tension control device 4 may be a dancer roll. Further, on the outlet side, a constant speed control device 5 for the strip 9 composed of an outlet side bridle roll is provided,
The speed of the strip 9 is set to a set value by the automatic speed controller ASR in light of the speed reference MRH.
Tension gauges 6a, 6b, 6c, 6d are provided behind the constant tension control device (entrance side bridle roll) 4 and between each block, and between the final block and the exit side bridle, and each of the blocks in each block 2 is provided. A drive motor M for driving the helper roll 3 is provided, and each drive motor M is controlled by the automatic voltage controller AVR for each block 2a, 2b, 2c.

The basic idea of the control method of the present invention will be described with reference to FIG. 2 in which the strip 9 is modeled as an elastic body. In FIG. 2, each block 2a, 2b, 2c
The force applied to the strip 9 therein is indicated by a white arrow (the leftward direction is the positive direction) 7. Further, the tensions measured by the tension control device (inlet side bridle roll) 4 and the tensiometers 6a, 6b, 6c and 6d provided on the outlet side of each block 2 are T ₀ , T ₁ , T ₂ and T _{3 respectively.} And
Then, the tension difference F ₁ generated in the first block 2a
Becomes F ₁ = T ₀ −T ₁ = ΔT ₀₁ (1). Similarly, assuming that the tension differences generated in the second block 2b and the third block 3b are F ₂ and F ₃ , respectively, F ₂ = T ₁ −T ₂ = ΔT ₁₂ (2) F ₃ = T ₂ −T ₃ = ΔT ₂₃ (3) Generally, if the tension difference between adjacent blocks is ΔT _{i-1 i} , then F _i = T _i-1 −T _i = ΔT _{i-1 i} (4). On the other hand, if the roll diameter of the i block is D _i , the gear ratio is g _i , and the total torque generated by the motor is τ _i , then F _i = G _i · τ _i , G _i = 2 / (D _i · g _i ) ( 5) Further, the torque τ _i exerted by all the drive motors of the i block is expressed by K _Ti of the drive motor of the i block, I _{i of} the load current, N _i of the number of motors, V _{i of} the terminal voltage, and back electromotive force. Is e _i , the back electromotive force coefficient is k _ei , the rotational angular velocity is ω _i , and the armature resistance is r _i , then τ _i = N _i · K _Ti · I _i = N _i · K _Ti · (V _i −e _i ) / r _i = N _i · K _Ti · (V _i −k _ei · ω _i ) / r _i (6) In equation (6), the motor ratings and various characteristics in the same block are expressed as the same. However, if different,

[0015]

[Equation 1]

[0016]

Meanwhile, when the deviation between the tension difference due to the set value of the tension difference F _i of measurements by the tension six adjacent blocks tension on the outlet side of each block and .delta.F _i, .delta.F the equation (5) _i = G _i δτ _i (7) Here, when the terminal electronic voltage operation of the drive motor of each block by tension control is performed, the motor rotation speed ω _i is constrained by the strip and is constant. δτ _i = N _i · K _Ti · δV _i / r _i (8) Therefore, δF _i = A _i · δV _i δV _i = (1 / A _i ) · δF _i (9) where A _i = N _i · G _i · K _Ti / r _i = 2N _i · K _Ti / (D _i
· G _i · r _i) Therefore, in order to correct the deviations .delta.F _i set value and the measured value of the tension difference F _i at inlet and outlet of each block, the terminal voltage operation amount of the drive motor of the i blocks formula Calculated from (9). This relationship can be expressed by the following equation in the first three blocks.
It becomes like (10).

[0018]

[Equation 2]

This relationship is not limited to three blocks, and in general for an i block, it is represented by a determinant of i rows.

Note that δV _i is a control output that originally sets the deviation δF _i to 0 once, but is integrated so that a steady deviation is not left even in the presence of a control modeling error or disturbance. Also, the response of this control can be adjusted by multiplying δV _i by an appropriate coefficient k (0 <k <1).

Next, each step of this control method will be described with reference to the flowchart of FIG.

First, as shown by S1 in FIG. 1, tensions S _i on the outlet side of the bridle roll on the inlet side of the annealing furnace and on the outlet side of each block are set. This tension is set in advance as a design value according to the temperature of each block, depending on the width, thickness and material of the strip and the shape of the helper roll. Next, as shown in S2, the difference ΔS _{i-1 i} between the set tensions on the inlet side and the outlet side of each block is calculated. Next, the annealing furnace is actually operated and the tension T _i is measured by each tensiometer (see S3), and the difference F _i = ΔT _{i-1 i} between the measured tensions on the inlet side and the outlet side of each block is calculated. (See S4). Next, a deviation δF _i = ΔS _{i-1 i} −ΔT _{i-1 i} between the set tension difference and the measured tension difference in each block is obtained (see S5), and the control amount δV _i of the drive voltage of the drive motor in each block is obtained. = A _i ^-1 · δF _i is obtained (see S6), and the drive motor is controlled (see S7). The steps S3 to S7 are repeated until δF _i becomes zero. Through the above steps, the tension in each block can be controlled non-interferingly according to the set value.

Next, the tension control device of the present invention will be described in more detail with reference to FIG.

First, the setting tensions of the tensiometers behind the inlet side bridle roll 4 and between the blocks 2a, 2b, 2c and between the final block and the outlet side bridle are S ₀ , S ₁ , S ₂ , respectively. and S _3, and _{T 0, T 1, T 2} , T 3 the tension caused by actual measurement in the same order, respectively. For example, regarding the first block 2a,
Difference in set tension between inlet side and outlet side of block 2a ΔS ₀₁ =
The difference between S ₀ -S ₁ and the measured tension ΔT ₀₁ = T ₀ -T ₁ is calculated. Measuring the tension T ₀ and T ₁ is determined to T ₀ -T ₁ after removing the noise associated with the measurement through the filter P respectively, through the set tension S ₀ -S ₁ limiter L, the motor M
In consideration of the driving ability of the above and the prevention of slip between the strip 9 and the helper roll 3, the difference is limited so as not to exceed a certain value. A difference δF ₁ = ΔS ₀₁ −ΔT ₀₁ between the set tension difference ΔS ₀₁ and the measured tension difference ΔT ₀₁ is calculated. Similarly for the other second block 2b and the third block 3b, the set tension differences ΔS ₁₂ , ΔS ₂₃ and the measured tension difference Δ are the same.
T ₁₂ and ΔT ₂₃ are calculated, and respective differences δF ₂ and δF ₃ are calculated.

After that, as described above, the control manipulated variables δV ₁ = A ₁ ^-1 δF ₁ and δV ₂ , of the control voltage of the drive motor,
Calculate δV ₃ for each block. The control manipulated variables δV ₁ , δV ₂ , δV ₃ of the respective control voltages are added to the drive voltage by the integrator I, respectively, and the drive voltage V ₁ , respectively.
The signals from the speed reference signal MRH are input as V ₂ and V ₃ to the automatic voltage controller AVR of the drive motor, and the drive of the helper roll 3 in each block is controlled. This operation is repeated until there is no difference between the set tension and the measured tension. As described above, the tension of the strip in each block is controlled so as to be the set value. It should be noted that the process from the setting of tension to the input of the control voltage of the drive voltage is controlled collectively by the microcomputer.

[0026]

As described above, according to the present invention, the tension control for each block does not affect each other, so that the optimum tension control can be realized.
High responsiveness can also be achieved. Moreover, since the model is based on physical constants such as motor constants, adjustment is easy. Further, since the control operation amount for each block can be obtained by the matrix calculation by the microcomputer, all the blocks can be controlled immediately regardless of the number of blocks.

As a result, it is possible to stably achieve the optimum tension target for the recent progress in thinning and widening of strips and also for strips of various sizes. It is possible to ensure a stable transfer in the annealing furnace, and to perform a predetermined heat treatment on any strip in a common annealing furnace.

[Brief description of drawings]

FIG. 1 is a flow chart showing each step of a furnace tension control method of the present invention.

FIG. 2 is a schematic diagram in which a strip for each annealing furnace composed of blocks is modeled as an elastic body for explaining the furnace tension control method of the present invention.

FIG. 3 is a schematic view of an embodiment of a furnace tension control device of the present invention.

[Explanation of symbols]

 1 continuous annealing furnace 2 block 2a 1st block 2b 2nd block 2c 3rd block 3 helper roll 4 constant tension controller 5 constant speed controller 6a tensiometer 6b tensiometer 6c tensiometer 6d tensiometer 9 strips

Claims (2)

[Claims] 1. An annealing furnace composed of a plurality of blocks, a helper roll for carrying a strip provided inside each of the plurality of blocks, and one and the other of an inlet side or an outlet side of a set of the plurality of blocks. Each block in a continuous annealing furnace comprising a constant speed controller and a constant tension controller for the strip respectively installed in the block, and a drive motor for driving the helper roll to keep the tension of the strip constant in each block. Of the control voltage of the drive motor of each block for controlling the tension of each block to a target value. the .DELTA.V = a ^-1 .delta.F where a by deviation .delta.F set value and the measured value of the to constants and formulated determined by the rating of the drive motor, tabs from the equation Tsu furnace tension control method of continuous annealing furnaces for controlling the tension in each block independently for each block without interfering phrase. 2. An annealing furnace comprising a plurality of blocks, a helper roll for strip transportation provided inside each of the plurality of blocks, and one and the other of the inlet side or the outlet side of the set of the plurality of blocks. Each block in a continuous annealing furnace comprising a constant speed controller and a constant tension controller for the strip respectively installed in the block, and a drive motor for driving the helper roll to keep the tension of the strip constant in each block. Is a furnace tension control device for a continuous annealing furnace for controlling the tension of (a), and (b) means for obtaining a difference in set tension and a difference in measured tension between the inlet side and the outlet side of each of the blocks; A means for obtaining a deviation δF between the set tension difference and the measured tension difference; and (c) a control operation amount δ for controlling the drive motor of the helper roll by the tension deviation δF. A furnace for a continuous annealing furnace comprising means for obtaining V by the following formula, and δV = A ⁻¹ δF, where A is a constant determined by the rating of the drive motor (d) and means for controlling the drive motor by the control operation amount δV. Internal tension control device.