JPS6054221A - Tension controlling method of strip - Google Patents

Abstract

PURPOSE:To simplify a control system, and to improve a dimension accuracy of a plate by raising a looper roll placed between stands when a strip is bitten into a lower side stand, and controlling a relative speed of the roll so that a looper tension becomes a prescribed tension. CONSTITUTION:When a strip 4 is bitten into a lower side stand 2, between adjacent stands 1, 2, a looper roll 3c is made to contact by pressing to the strip by operating an automatic arm angle control part 10 by a signal of a rolling reduction load cell 9, and raising an arm 3b up to a prescribed angle theta by a hydraulic cylinder 3d. A load is detected by a load cell 5 of a looper 3, and a strip tension between the rolls is made constant by controlling a relative speed of a roll motor M of the upper side stand 1 by a roll speed control part 11 so that its load becomes a prescribed value. A tension of a strip is made constant, and a plate accuracy is improved by a simple control system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the tension of a hot strip mainly in a finishing mill etc. using a speed control device that controls the tension of a strip at a joint of the relative speed of rolls of adjacent stands, and a looper. Regarding.

Generally, tension between stands in a finishing mill or the like is controlled using a looper and/or a speed control device that controls the relative speed of rolls of adjacent stands.

Normally, the looper controls the strip tension between the stands and the loop amount to maintain the strip tension stably.The strip tension is controlled by controlling the driving torque of the louver drive device, and the loop amount is The arm angle in the looper is controlled by adjusting the relative roll speed of the stand.

By the way, the relationship between the looper and the strip can be considered as a kind of spring system if the strip is considered to be a completely elastic body and its plate elongation is ignored. If you look at it, it will look like the one shown in Figure 1. Figure 1 is a block diagram showing the relationship between the looper arm angle θ, strip tension σ, strip speed V (stand roll speed), and looper drive torque τ.If the strip speed is changed by Δvi, the transmission element There is a tension fluctuation corresponding to the transfer function Ga (S), but this tension fluctuation is due to the interference coefficient γ
The louver driving torque is varied accordingly. On the other hand, when the driving torque of the looper is changed by Δτ, this variation and the variation caused by the change in the stripping speed are added, and the transfer element transfers the louver arm according to its transfer function Gθ(S). Although it causes a variation of θ in the angle,
At the same time, this variation in arm angle causes a tension variation corresponding to the interference coefficient γ. This variation is the transfer function G
This is combined with the tension fluctuation corresponding to a(S) to cause a fluctuation in the tension σ. Therefore, controlling either the arm angle or the strip tension will also change the other, making it difficult to stabilize both at the same time.

For this reason, in recent years, attempts have been made to make multivariable control systems non-interfering, and FIG. 2 is a block diagram thereof. This is as follows (for the multivariable control system of Equation 11, θref +σ
ref and feedback data θ, σ are combined, proportional and integrated in the control device, and the transfer function KG” (
It is characterized in that it is input from a transmission element of 0) to a louver rolling system of several G(w+) (Japanese Patent Laid-Open No. 57-160510).

However, K: Transfer coefficient G-' (0): Inverse matrix of G←) at w=O The premise is to always accurately understand the dynamic characteristics of the louver. It is a nonlinear system that includes many parameters such as the arm angle of the louver, the cross-sectional area of the strip, and the Young's modulus of the strip, and although a completely non-interfering state can be expected, there are limits to stable control of the louver arm angle and strip tension. .

The present invention has been made in view of the above circumstances, and its purpose is to select one of the elements of the arm angle of the louver and the roll speed of the stand, that is, the strip speed, which interfere with each other. An object of the present invention is to provide a method for controlling strip tension in which the arm angle is fixed at a predetermined desired position and thereafter the strip tension can be accurately controlled by adjusting the strip speed.

The looper control method according to the present invention is a method in which the tension of the strip is controlled by adjusting the relative speed of rolls of adjacent stands using a speed control device and adjusting the arm angle of the louver. Immediately after the arm of the louver disposed between both stands is rotated from the position where it contacts the strip to a predetermined angle, the speed control device is activated, and when the arm angle reaches a predetermined value, the arm is rotated. is fixed at the position, and thereafter the tension is controlled by a speed control device.

The method of the present invention will be specifically explained below based on the drawings showing its implementation state. FIG. 3 is a schematic diagram showing the implementation state of the method of the present invention, in which 1.2 indicates adjacent stands in a finishing mill, 3 indicates a louver, and 4 indicates a strip.

The louver 3 is located between the stands 1 and 2, and presses the strip 4 passed from the direction of the white arrow upwards from its lower surface side, applying appropriate tension to the strip 4 and tightening the tension between the stands 1 and 2. It is designed to ensure an appropriate amount of strip loops. The louver 3 is constructed by pivotally supporting a roll 3c on the upper end of an arm 3b whose lower end is pivotally supported on a support base 3a, and connecting the operating rod of a hydraulic cylinder 3d to the middle part of the arm 3b. By operation, the arm 3b is moved to a required angle and maintained at that position. The arm 3b is provided with a load detector 5 such as a load cell and an arm angle detector B6, and the hydraulic cylinder 3d is provided with a locking device such as a brake. In addition, 8 is a pulse generator attached to the roll drive motor M of the stand 1, and 9 is a load cell for detection of a rolling type in the stand 2.

10 is an arm angle automatic control unit (A P
C), the louver 3 is moved from its standby position to a set position at a predetermined timing, and the arm angle of the louver 3 is locked at the position. Reference numeral 11 denotes a roll speed control section of the stand 1, which also controls the tension of the strip at a predetermined timing.
After starting and locking the arm angle of the louver 3, the strip tension is controlled mainly by adjusting the relative speed of the stand rolls.

The method of the present invention will be explained below according to the control procedure based on the operation diagrams shown in FIGS. 4(a) to 4(b).

(11 Before threading to finishing mill (adjacent stand 1
．． 2) Before the strip is caught in the downstream stand 2), the hydraulic cylinder 3d is operated to move the roll 3c of the louver 3 to the standby position directly below the pass line of the strip 4, or from this point, as shown in FIG. 4(A). is fixed at the lowest lowest position to prevent the top of the strip 4 from colliding with the louver during passing, and roll speed control that starts at the same time as the top of the strip 4 is caught in the downstream stand 2, which will be described later. When the strip 4 is pulled due to strip tension control by the section 11, the impact of the strip against the louver roll 3C prevents the roll 3C from bending or the strip 4 from elongating.

(2) After threading (after the top of the strip 4 is caught in the downstream stand 2) 1) Automatically adjust the arm angle for each load cell output signal change when the top of the strip 4 is caught in the stand 2 When detected by the control unit IO and the roll speed control unit 11,
The automatic arm angle control section 10 causes the hydraulic cylinder 3d to extend its operating rod at a predetermined constant speed, in other words, the looper arm 3d is rotated and raised from the standby position toward the pass line side of the strip 4 at a predetermined angular speed. A control signal is output to allow the arm 3b of the louver 3 to start rising as shown in FIG. will be started. The state of the strip 4 between the stands 1 and 2 at the time when the strip tension by the roll speed control unit 11 starts to act effectively is that the strip 4 is in a slightly looped state as shown in FIG. 4(c). , as shown in FIG. 4(D) (Although it is possible that the strip 4 does not loop and is located on the original path line, if the roll speed control section 11 starts to work effectively, In the case shown in c), the loop of the strip 4 is eliminated, and in the case shown in FIG. Control takes place.

ii), the roll 3c of the louver 3 rises [in the case of FIG. When the arm angle automatic control unit 10 detects a load signal from a load detector provided on the arm 3b that comes into contact with the lower surface, automatic control of the arm angle is started, and the arm angle θ read from the arm angle detector is input in advance. The set angle θ. A predetermined control signal is output to the hydraulic cylinder 3d until the looper roll 3 is reached.
The looper roll 3c is moved slowly downward, and in the case of FIG. When the arm angle θ approaches the set angle θ0 within a predetermined value, the moving speed of the louver roll 3c is reduced.

iii) When the arm angle θ matches the set angle θ0, the hydraulic cylinder 3d is stopped at that point, and at the same time the locking means is activated to fix the louver 3 at the position as shown in FIG. 4 (g), and the arm angle is adjusted. The control by the automatic control section 10 is ended, and thereafter the control of the strip tension by the roll speed control section 11 is continued.

Specifically, the control of the inter-stand strip tension by the roll speed control section 11 is performed as follows. That is, the load, that is, the driving torque τ of the looper is read from the load detector 5 attached to the looper arm 3d, and when the arm angle is already fixed, the known arm angle θo is read.
1 Length of arm 3c lr, height from the pivot point of the lower end of arm 3c to the pass line of strip 4 '3' + arm 3c
Distance from the bottom pivot point to the center of the front stand
x, distance to the center of the rear stand 7! Calculate the tension T of the strip 4 according to the following formula (3) based on , this calculated value T is a predetermined set tension T. A control signal is output to the motor M of the stand 1 to adjust the roll speed so as to match the . Note (3)
The equation can be approximately rewritten as equation (4).

However, W: load of the strip between the stands Wo: load of the louver C: constant The relationship between the roll rotation speed of the stand 1 and the strip tension between the stands may be determined by appropriately adopting a conventional method.

As described above, in the method of the present invention, when the strip is caught in the downstream stand between the stands, the arm angle of the looper is fixed at a predetermined value, and the strip tension is controlled by adjusting the stand roll speed. As a result, the configuration of the control system is simplified, tension fluctuations are reduced, plate thickness and width accuracy are improved, and loop amount fluctuations are also relatively small, reducing operational troubles. It has the following effects.

Of course, the same applies to the power transmission looper.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a general strip tension control system, FIG. 2 is a block diagram of a conventional control system, and FIG. 3 is a schematic diagram showing the implementation state of the method of the present invention together with its control system.
FIGS. 4A to 4G are explanatory diagrams showing the looper control procedure in the method of the present invention. 1.2...Stand 3...Looper 3b...Arm 3c...Roll 3d...Hydraulic cylinder 1o
... Arm angle automatic control section 11 ... Roll speed control section Patent applicant: Sumitomo Metal Industries, Ltd. Agent Patent attorney: Noboru Kono

Claims (1)

[Claims] 1. In a method in which the relative speed of rolls of adjacent stands is adjusted by a speed control device and the tension of the strip is controlled by the joint of the arm angle of the looper, immediately after the strip is bitten by the downstream stand of the adjacent stand, both The arm of the looper disposed between the stands is rotated from the position where it contacts the strip nib to a predetermined angle, and the speed control device is activated, and when the arm angle reaches a predetermined value, the arm is rotated to that position. A method for controlling the tension of a strip, the method comprising: fixing the tension on the strip, and then controlling the tension using a speed control device.