JPH0362483B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a speed control device for controlling the tension of a strip by adjusting the relative speed of rolls of adjacent stands;
The present invention also relates to a method of controlling the tension of hot strips, mainly in finishing mills, etc., using a looper.

Generally, tension between stands in a finishing mill or the like is controlled using a looper and/or a speed control device that adjusts the relative speed of rolls of adjacent stands. Normally, the looper controls the strip tension between the stands and the loop amount to keep the strip tension stable. The arm angle is controlled by adjusting the stand roll relative speed.

By the way, regarding the relationship between the looper and the strip, if we consider the strip as a completely elastic body and ignore its plate elongation, we can think of it as a kind of spring system. 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, the strip tension σ, the strip speed v (stand roll speed), and the looper drive torque τ.If the strip speed is changed by Δvi, the transmission element is the transfer function Ga
A tension variation corresponding to (S) occurs, and this tension variation gives a variation to the looper drive torque in accordance with the interference coefficient γ. 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 strip speed are added, and the looper arm is transferred from the transfer element to the 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 added to the tension variation corresponding to the transfer function Ga(S) described above to cause a variation in the tension σ. Therefore, controlling either the arm angle or the strip tension will 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 the multivariable control system non-interfering, and FIG. 2 is a block diagram thereof. This is done by adding θref, σref and feedback data θ, σ to the multivariable control system of equation (1) below, and proportionally and integrally integrating it in the control device to transfer the transfer function KG ^-1 (0). From the elements, θ σ = G (w) Δv Δτ … (1) where G (w): transfer function Input Δv and Δτ expressed by the following equation (2) into the looper rolling system of the transfer function G (w), respectively. (Japanese Unexamined Patent Publication No. 160510/1983).

Δv Δτ=KG ^-1 (o) Δx Δy …(2) where K: Transfer coefficient G ^-1 (0): Inverse matrix of G(w) at w=O Δx, Δy: Δx Δy=F(s)・Δθ Δσ However, this type of control method relies on always accurately understanding the dynamic characteristics of the looper, but the dynamic characteristics of the looper depend on the tip of the strip, the backward rate,
It is a nonlinear system that includes many parameters such as the looper arm angle, strip cross-sectional area, and strip Young's modulus, and a completely non-interfering state cannot be expected, and there are limits to stable control of the looper arm angle and strip tension. Ta.

The present invention has been made in view of the above circumstances, and its purpose is to predetermine one element of the looper arm angle and the strip tension, which interfere with each other, in other words, the looper arm angle. It is an object of the present invention to provide a method for controlling a strip tension by fixing it at a desired position and then controlling the strip tension accurately by adjusting the strip speed.

A method for controlling the tension of a strip according to the present invention is a method for controlling the tension of a strip by adjusting the relative speed of rolls of adjacent stands using a speed control device and adjusting the arm angle of a looper. Immediately after the looper is caught in the stand, the arm of the looper disposed between the two stands is rotated from the standby position during strip threading to a predetermined angle and fixed at that angle, after which the speed control device It is characterized by controlling the tension.

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 and 2 are adjacent stands in a finishing mill, 3 is a looper, and 4 is a schematic diagram showing how the method of the present invention is implemented.
indicates a strip. The looper 3 is located between the stands 1 and 2, and presses the strip 4 passed from the direction of the white arrow upward from its lower surface side, applying appropriate tension to the strip 4 and attaching it to the stands 1 and 2. It is designed to ensure an appropriate amount of strip loops in between. The looper 3 is constructed by having a roll 3c pivoted on the upper end of an arm 3b whose lower end is pivotally supported on a support base 3a, and an operating rod of a hydraulic cylinder 3d connected to the middle part of the arm 3b. Arm 3 by operation
b 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 6, 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 detecting the rolling weight in the stand 2.

Reference numeral 10 denotes an automatic arm angle control section (APC) of the looper 3, which moves the looper 3 from its standby position to a set position at a predetermined timing and locks the arm angle of the looper 3 at that position. It is set as. Reference numeral 11 denotes a roll speed control section of the stand 1, which also starts tension control of the strip at a predetermined timing, and after locking the arm angle of the looper 3, controls the strip tension mainly by adjusting the relative speed of the stand roll. It is designed to control tension.

The method of the present invention will be explained below in accordance with the control procedure based on the operation diagrams shown in FIGS. 4A to 4B.

(1) Before passing the strip through the finishing mill (before the strip is inserted into the downstream stand 2 of the adjacent stands 1 and 2), operate the hydraulic cylinder 3d to move the roll 3c of the looper 3 as shown in Fig. 4A. It is fixed at the standby position directly below the pass line of strip 4 or at the lowest position lower than this, and when threading the strip 4
The strip 4 was pulled to prevent the top of the strip 4 from colliding with the looper, and to control the strip tension by the roll speed control section 11, which starts at the same time as the top of the strip 4 is bitten by the downstream stand 2, which will be described later. At this time, the roll 3c is prevented from bending due to the impact of the strip against the looper roll 3c, or the strip 4 is prevented from elongating.

(2) After threading (after the top of the strip 4 is caught in the downstream stand 2) The automatic arm angle control unit 10 records the change in the output signal of the load cell when the top of the strip 4 is caught in the stand 2. , when detected by the roll speed control section 11, the arm angle automatic control section 10 causes the hydraulic cylinder 3d to extend its operating rod at a predetermined constant speed, in other words, to strip the looper arm 3d from the standby position at a predetermined angular speed. A control signal is output to allow the stand 1 to rotate and stand up toward the pass line side of the looper 3, and the arm 3b of the looper 3 starts to rise as shown in FIG. Strip tension control by roll speed control is 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 section 11 starts to act effectively is that the strip 4 is in a slightly looped state as shown in FIG. As shown in Fig. 4D (it is conceivable that the strip 4 does not loop and is located on the original path line), when the roll speed control section 11 starts to work effectively, the case shown in Fig. 4C occurs. In this case, the loop in the strip 4 is eliminated, and in the case shown in FIG. 4D, control is performed in the manner described below to apply a predetermined tension to the strip 4.

The roll 3c of the looper 3 rises [in the case of FIG.
The roll 3c comes into contact with the lower surface of the strip 4,
When the arm angle automatic control unit 10 detects a load signal from a load detector provided on the arm 3b, automatic control of the arm angle is started, and the arm angle θ read from the arm angle detector is changed to the previously input setting angle θ ₀ A predetermined control signal is output to the hydraulic cylinder 3d until the fourth
In the case of FIG. 4, the looper roll 3c is gently lowered, and in the case of FIG. It moves so as not to cause any disturbance, and when the arm angle θ approaches the set angle θ ₀ within a predetermined value, the moving speed of the looper roll 3c is decelerated.

When the arm angle θ matches the set angle θ ₀ , the hydraulic cylinder 3d is stopped, and at the same time the locking means is activated to fix the looper 3 at the position shown in FIG. After that, the control by the roll speed controller 11 continues to control the strip tension.

Specifically, the inter-stand strip tension is controlled by the roll speed control section 11 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 θ ₀ , the length r of the arm 3c, Height y from the pivot point at the lower end of arm 3c to the pass line of strip 4, distance x from the pivot point at the lower end of arm 3c to the center of the front stand, distance x' to the center of the rear stand, relative to the pass line on the exit side of stand 1. Based on the exit angle α of the strip 4 and the entrance angle β of the strip 4 with respect to the pass line on the entrance side of the stand 2, the tension T of the strip 4 is calculated according to the following equation (3), and this calculated value T is determined in advance. A control signal is output to the motor M of the stand 1 to adjust the roll speed to match the set tension T ₀ . Note that equation (3) can be approximately rewritten as equation (4).

T=τ−(W+W ₀ )rcosθ/(yc
osβ+x′sinβ)−(ycosα+x・sinα)…(3)
T=τ−r(W+W ₀ ) cosθ/C/2r ² (1/lx
-1/lx') sin2θ...(4) However, W: Load on the strip between the stands W ₀ : Load on the looper C: Constant The relationship between the roll rotation speed of stand 1 and the strip tension between the stands is conventionally established. It is sufficient to adopt the appropriate method.

As described above, in the method of the present invention, when the strip is caught in the stand on the downstream side, the looper is rotated from the standby position during strip passing to a predetermined angle and fixed at that position. Therefore, the interference between the looper arm angle and the strip tension immediately after threading can be easily eliminated, the control system configuration is simplified, and control accuracy is improved.
Furthermore, the present invention has excellent effects such as improved responsiveness and a rapid transition to a stable steady-state operating state.

In the above embodiment, a brake is used as a means for locking the looper arm. However, when a hydraulic motor, hydraulic cylinder, etc. are used, the closing operation of a servo valve for hydraulic control or the servo valve is necessary. The same effect as using a brake can be obtained by means such as cutting off the operating power source. Also, when using a looper motor, a brake is used.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a general strip tension control system, Fig. 2 is a block diagram showing a conventional control system, 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 4E 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, 10...
Arm angle automatic control section, 11... Roll speed control section.

Claims (1)

[Claims] 1 In a method of controlling the tension of the strip by adjusting the relative speed of rolls of adjacent stands using a speed control device and adjusting the arm angle of the looper, immediately after the strip is bitten by the downstream stand of the adjacent stand, both stands The arm of the looper placed between the strips is rotated from the standby position during strip threading to a predetermined angle and fixed at that angle.
A method for controlling tension in a strip, characterized in that the tension is then controlled by the speed control device.