JPS62192206A - Method and device controlled tension between stands for hot strip continuous finishing rolling mill - Google Patents

Abstract

PURPOSE:To control tensions with the high accuracy in accordance with strip passing states by controlling a strip tension by using both a tension detector between stands and a looperless controller. CONSTITUTION:A detector for tensions of a strip S between finishing rolling mills Fi and F>=+1 consists of a mechanical system containing such as a cylinder 2 of a tension detecting roll 1 and a load cell 3 supporting the cylinder 2. A tension control system jointly consists of the above tension detector and a looperless controller which controls tensions based on a rolling torque and rolling reaction force at the mills Fi and Fi+1. When a strip is passed, the roll 1 is lifted higher than the pass line and a tension is directly detected by the load cell 3 and a computer 5 operates and controls tensions between mills. When sledging or runout occurs, the roll is downed below the pass line and the looperless controller using a computer 20 operates and controls tensions based on data such as a rolling torque and a rolling reaction force of the mills Fi and Fi+1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for controlling the tension of strip between each stand of a continuous hot strip finishing mill.

[Conventional technology]

The tension between each stand of a continuous hot strip steel finishing mill is a factor that has a large effect on the dimensional accuracy, shape, and rootability of the rolled material. For this reason, various devices have been proposed to maintain the tension at a predetermined value.

The tension control that has been proposed so far is the looper method (September 1, 1980), which uses a mechanical looper device to keep the tension acting on the rolled material constant by balancing the looper drive torque and the torque caused by tension. (Refer to pages 306-307 of ``Theory and Practice of Sheet Rolling'' published by the Japan Iron and Steel Institute) and the tension can be calculated indirectly from the rolling a drive torque and rolling load.
There are two main types: the loopless method (see pages 307 to 308 of the same document), in which the tension is controlled at a constant value.

[Problems to be Solved by the Invention] In the looper method, the tension of the strip is adjusted by torque control (current) of a looper motor, and the louver angle is maintained constant by speed control of a mill motor.

However, in the looper type configuration, it is unavoidable that the looper angle control and the inter-stand tension control interfere with each other. In other words, in this louver method, as shown in FIG.
If the arm A of the looper device is at an angle θ1 when the metal strip S is running, and the tension increases by 8T'2 due to a disturbance, then in order to perform control to keep the tension constant, As shown in the same figure + b), set the angle to the arm to 0.
2 to reduce the louver angle. In response to this change in the looper angle, the roll speed of the entry side roll is increased by V as shown in Figure [C], and the louver angle is thereby changed to the original value in order to compensate for the loosening of the tension at 41. Control is performed to return to θ1. In this way, in order to control the tension between the sukun I and the sukun I by controlling the louver angle and tension control (M), the tension changes as a result of changing the louver angle control and the roll speed. In this case, the tension is corrected by changing the looper angle, but as in the case above, the roll speed is also changed, which causes the tension to change, and louver angle control and tension control are mutually exclusive. It becomes an interfering system.

In addition to such control system interference, tension detection includes dynamic fluctuations such as inertia and centrifugal force caused by looper angle fluctuations, and the looper arm has a large moment of inertia and a mechanical resonance point. For this reason, it cannot be used to manufacture products that require high dimensional accuracy. In particular, in recent years, with the expansion of the manufacturing range, the enlargement of equipment, and the feasibility of improving performance, we are manufacturing ultra-thin products of 30111 or more, such as those for line pipes, from ultra-thin products of 30111 or more, such as those for line pipes. In the case of objects, it is necessary to make the louver device stronger, resulting in an increase in the moment of inertia, and when manufacturing thin objects, this increased moment of inertia has a negative effect on dimensional accuracy.

On the other hand, although non-interference has been attempted in recent years, it is similar in principle to the control method in the louver device described above, in which the tension is kept constant by balancing the looper drive torque and the torque caused by the tension, and in the low frequency range. Stability has been achieved.

Furthermore, if the theoretical model is completely elucidated and actual parameter fluctuations can be compensated for, complete non-interference would be possible;
This technological level has not yet been reached, and non-interference during transient periods has not yet been achieved.

Furthermore, the Loopaless method uses a model formula, and the tension between the stands is detected by the mill motor speed calculated from this model formula using the values of rolling torque and rolling reaction force, and the tension between the stands is controlled. There is.

In this loopless method, a control system is configured that feeds back the inter-stand tension calculated based on rolling theory, so fluctuations in physical properties depending on the material, temperature, etc. of the rolled material have a large influence on the control system. Therefore, there is a limit to increasing control accuracy. In addition, in continuous hot rolling mills, the elastic range of the rolled material is narrow, and the ratio of the tension component to the rolling force is extremely small. For this reason, in hot rolling based on low-tension threading, the accuracy of tension detection is low, and absolute tension cannot be obtained in some respects.

In addition, in the case of the looper type, in addition to problems caused by interference in the control system, the moment of inertia increases due to the enlargement of the looper equipment due to the expansion of the manufacturing range as mentioned above, making it difficult to maintain high control accuracy. ing.

The present invention was created in view of the above-mentioned problems, and utilizes a direct tension control method using an inter-stand tension detection device, and a combination of this direct tension control method and a loopless method to take advantage of the respective advantages. The purpose of this is to perform tension control with high precision according to the sheet threading situation.

[Means for solving problems]

In order to achieve the above object, the present invention controls tension during sledging of a strip running between each stand of a rolling mill and when the strip runs out of the downstream stand by controlling the tension between the stands by the rolling torque and rolling load of the rolling rolls. The tension is controlled by a control system that calculates and detects the tension and controls the tension during sheet threading. It is characterized by a control system that directly detects the vertical load of the rolling mill and calculates and controls the tension between the stands.Furthermore, in order to perform such control, the rolling torque of the rolling rolls Equipped with a looperless control device that calculates and detects the tension between the stands based on the rolling load and controls the tension, and a tension detection roll that moves up and down between the lower levels on both sides of the pass line, the vertical load of the strip that is applied to the tension detection roll is detected. A tension detection device is provided to detect and calculate and control the tension between the stands, and the looperless control device is operated when the strip knob is sledged and the downstream side stand bottom slips out, and the tension detection device is operated when the plate is threaded. Features.

〔Example〕

Hereinafter, the present invention will be specifically described based on embodiments shown in the drawings.

FIG. 1 is a block diagram of a control system in this embodiment.

Hot finishing mill F, and F. Between 1 and 2, there is a strip S.
As a tension detection device for directly detecting the tension of the tension detection roll 1, a machine such as a cylinder 2 that drives the tension detection roll 1 and a load cell 3 that supports the cylinder 2 and detects the vertical load that the strip S loads on the tension detection roll 1 is used. The system is in place.

In addition, the tension control system includes the above-mentioned tension detection device of the direct detection method using the tension detection roll 1 and the hot finishing rolling machine F+.
, Ft-+, and a loopless control device that controls the rolling torque and rolling reaction force.

The tension control system includes a low-pass filter 4 that removes signal ripples from the load cell 3, a tension calculator 5, and an arithmetic unit 6 that corrects the Young's modulus of each net type in accordance with the temperature of the strip on the entry side based on the Young's modulus correction pattern. , a proportional-integral controller type tension control device 7, a limiter 8, and a roll drive device 9. Furthermore, 10 to 12 are low-pass filters, 13 to 18 are contact switches, 19 is a conditional circuit, and 2
0 each indicates a tension calculator as a control element of the looperless control device.

In the block diagram, when threading the strip S, the tension detection roll 1 is raised to a level above the pass line by the cylinder 2, and the tension between the hot finishing mills F and F, 41 is directly detected by the load cell 3. , a low-pass filter 4 removes ripples from the detected values, and a tension calculator 5 removes ripples from the detected values, and a hot finishing mill F, and F. Control for calculating the tension between 1 and 2 is performed by a tension detection device system.

In addition, during sledging and tailing, the tension detection roll 1 is lowered to a lower level than the pass line, and the tension calculator 20 calculates the loop from data such as rolling torque and rolling reaction force of the hot finishing mills F and F8°. Tension calculations are performed by a system of controllers.

Since the calculation by the tension calculator 5 is performed at the fixed position of the tension detection roll 1, the static loads used in the calculation include the strip bending load Pb, the strip distribution load P,
, , and the own weight Pr of the tension detection roll 1 are considered, and the calculation formula for the case in FIG. 2 is as follows.

W H[5in(tan-'δ/ &) +5in(t
an-'δ/b)]=KI [P/(WH)-2E
H2-3]K+=sin [(tan-'δ/ lJ
) 15in(tan-'δ/a)]-'2 = 113
/ (4b"b") K3-ρ1/2.

However, P,=EWH'J3/<4b3b")1=VzpW
H1 ρ: Specific gravity of the rolled material W: Plate width H: Plate thickness E: Young's modulus In addition, in this secondary method, the Young's modulus E is a function of the temperature at the entrance of the stand, and the correction according to the steel type is calculated using the Young's modulus correction pattern using a calculator. 6, and the correction value is calculated using the tension calculator 5.
Enter.

Based on the above calculation formula, the tension σT)I caused by the tension detection roll 1 is basically fed back to the tension control device 7,
The roll drive device 9 changes the mill speed of the stands F and controls the tension between the stands.

The operating method of the tension detection roll 1 is as shown in the shift diagram of the tension detection roll in FIG. 3 and the time chart in FIG. 4, as shown in FIG. After 1 stand metal-in, soft touch control is performed and tension detection roll 1 is
is raised to a level above the pass line, and at the upper limit, inter-stand tension control by the tension detection roll 1 is started. Then, F. While performing the no-voice control before the stand ash removal, F. the tension horn detection roll 1 is operated so as to complete its descent to the lower limit just before the stand metal is turned off.

By the way, the tension detection roll 1 directly detects the strip S.
In the tension detection device for detecting the tension of , the tension detection roll 1 needs to be lowered to a lower level position than the pass line when the leading and trailing ends of the strip S pass. In other words, the tension cannot be controlled by the tension detection device including the tension detection roll 1 during slancing and when the downstream stand ends. Therefore, tension control for the tip and end portions is performed by a looperless control device.

The calculation formula used by the tension calculator 20 of the loopless control device is to calculate tension from rolling torque and rolling reaction force, as is conventionally known. That is, the tension T between the stands
, is given by the following equation.

Tr-[aFG+bTb]/CTf
: Inter-stand tension T, : Rear tension a : Torque arm (-G0/F0) F : Rolling reaction force (at no tension) G : Rolling torque Go : Rolling torque (at no tension) b, c: constant Here, the strip S range under control by the tension meter roll 1 is defined as MID, and the temperature range of the tip of the strip S from F2.1 stand metal-in to the upper limit position of the tension detection roll 1 [D] is set as TOP, and control is performed by switching to the looperless control device for this TOP portion. That is, for the TOP part of the strip S, the tension between stand units σpre = Tt / W-
H is determined and the control is continued, and when it becomes obsolete, an operation is performed to switch to control based on the tension σ1M directly detected by the tension detection roll 1.

In switching the measurement control from the tension σFTC detected by this looperless control device to the tension σTH detected by the tension detection device which is directly detected by the tension detection roll 1, the low-pass filter 12 controls the tension σFTC detected by the looperless method.
The receiver has the function of removing ripples and smoothing the transition to the directly detected tension σTM.

As a result, even in the strip 50MID range, the tension σ7M is passed between the timers by the condition circuit 19 to prevent sudden disturbance of the feedback signal, and then the tension is switched to the tension σTH to perform predetermined control. Also,
The directly detected tension σ0M and the tension detected by the looperless control device σFTC pass through a low-pass filter 10.11, and at this time, the respective moving average values σd and σFTC are obtained, and the control using σT (in the case of MID range) is performed. When each lock is turned off, the looperless relative tension (σFTC
−σ, A, 10σTM)”6FT.F after the MID area is turned off, this looper relative tension σ until the stand metal is turned off.
F7. Control is performed by (-σ4.X).

This is done in consideration of the fact that the tension σFTC detected by the loopless method is controlled by the tension σTM directly detected by the tension detection device, so the absolute value at the time of switching does not match.This σFTC has ripples removed by the low-pass filter 12. Ru.

Note that the detected tension σFTC of the looperless control device generally includes ripples, and the low-pass filter 4°10-12
Since the modified moving average has a linear phase characteristic, the phase lags significantly and becomes unstable, requiring a filter with a second-order lag.

〔Effect of the invention〕

As explained above, in the tension control method of the present invention, by applying control systems with different tension detection and control methods depending on the steel plate threading situation, the characteristics of each control system are optimally utilized to achieve high performance. Accurate tension control is possible. Furthermore, during sledging and tail-cutting, the roll is lowered from the tension detection roll path line of the tension detection device and is in a non-contact state with the steel plate, so that the threading stability can be improved. Furthermore, control accuracy is further improved because the tension detection roll is not affected by tension disturbances when it moves up and down.

[Brief explanation of drawings]

Fig. 1 is a brochure diagram of the control system in the embodiment of the present invention, Fig. 2 is an explanatory diagram of tension control by the tension detection roll, Fig. 3 is an explanatory diagram showing the shift of the tension detection roll, and Fig. 4 is tension detection. A time chart showing tension waveforms and composite waveforms obtained by the direct detection method based on the roll position and the looperless control device, and FIG. 5 is an explanatory diagram showing interference in the control system of the conventional louver device.

Claims (1)

[Claims] 1. Tension control during sledging of the strip running between the stands of the rolling mill and when the bottom of the downstream stand falls off is performed by calculating and detecting the tension between the stands using the rolling torque and rolling load of the rolling rolls. The tension is controlled by a control system that controls the tension, and the tension during sheet threading is controlled by raising the tension detection roll of the tension detection device installed between the stands above the rolling pass line and directly applying the vertical load applied to the tension detection roll. 1. A method for controlling tension between stands of a continuous hot strip steel finishing rolling mill, characterized in that the tension is controlled between stands in a continuous hot strip steel finishing rolling mill. 2. Between the stands of the rolling mill, there is a loopless control device that calculates and detects the tension between the stands based on the rolling torque and rolling load of the rolling rolls and controls the tension, and a tension detection roll that moves up and down between the upper and lower levels across the pass line. and a tension detection device for calculating and controlling the tension between the stands by detecting the vertical load of the strip applied to the tension detection roll, and activating the looperless control device when the strip is sledged and the downstream stand ends, An inter-stand tension control device for a continuous hot strip finishing rolling mill, characterized in that the tension detection device is activated during strip passing.