JPS58205610A - Method for controlling tension between stands of continuous rolling mill - Google Patents

Abstract

PURPOSE:To stabilize the control of tension between the stands of a continuous rolling mill and to improve the dimensional accuracy of a product by changing the control gain of a tension control device at every timing at which the preceding and succeeding ends of a material to be rolled passes through the respective stands successively. CONSTITUTION:The timing for biting of a rolling material 1 is detected with a detector 9 for material position at every change in the number of the stands across which the material travels in the continuous rolling mill by passing through the stands successively in the continuous rolling mill of m-stand (m is >=3) constitution. When an arithmetic device 10 for control gain receives the biting signal Ti of the material, the device operates the gain for generation of the tension corresponding to the number of the stands across which the material 1 travels. Said device calculates the optimum control gain corresponding to the number of the stands in accordance with the calculated value and the frequencies Wc, F of crossing angles and outputs the same to a tension control device 6 so as to change the setting. As a result, the tension between the stands is controlled always stably.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an inter-stand tension control device in a continuous rolling mill for wire rods, steel bars, hoist strips, mills, etc., and particularly relates to an inter-stand tension control device for controlling the inter-stand tension control system for rolling materials. The present invention relates to an inter-stand tension control method in which the optimum #LK is set each time the leading and trailing ends of a rolling mill pass through each stand of a continuous rolling mill.

[Technical background of the invention]

In a continuous rolling mill, if there is an error in the roll speed settings of each stand, abnormal tension or compression force will work between the stands, and if abnormal tension occurs between the stands, it will not only affect the dimensional accuracy of the material. This may sometimes lead to material breakage. Therefore, stand opening force control of a continuous rolling mill is an important control technology from the viewpoint of product dimensions and operation.

As a method for controlling tension between stands of such a continuous rolling mill, the following methods have been conventionally known.

■ A tension detection device is installed between the stands, this detection device detects the tension between the stands, and the roll pigeon speed of the rolling mill is corrected based on the signal of the difference between the detected eye power and the target tension.
A method of controlling the tension between stands.

■ Without installing a tension detection device between the stands, the tension between the stands is detected from the rolling load and rolling torque, and based on the signal of the difference between the detected tension and the target tension, rolling is performed in the same way as in ■ above. A method of adjusting the roll peripheral speed of the machine and controlling the tension between the stands to about 111tE.

Here, the method (2) above differs from the method (2) in the method of detecting the tension between the stands, but is the same as the method (2) in that it corrects the circumferential speed of the rolls of the rolling mill.

FIG. 1 is a diagram illustrating a conventional inter-stand tension control method corresponding to method (2) above using a continuous rolling mill with a three-stand configuration. In FIG. 1, a rolling material JFi is rolled in a rolling mill 1 of each stand, and the rolling mill of each stand is driven by an electric motor 1 and its speed control device. +1
To explain the method of controlling the tension 'fat between the two stands, the tension detection device 5 detects the tension tf between the stands φ1 to 2, and the detected tension tf,
, target tension between lotus l and two stands tiLIF,
It is compared with 1. The compared good signal (tension deviation) Δt
l=tagr, 1-Ll, 1 is inputted to each tension control device, and each tension control device calculates the roll speed correction lid Δt1 of the +1 stand based on this tension deviation Δtl.

The roll speed correction amount ΔNl is input to the speed side #1fll4 of the drive motor l of the +1 stand, the roll circumferential speed ΔW1 of the rolling mill of the +1 stand is corrected, and the inter-stand tensions tf and g are controlled precisely. Ru. In addition, φ2~◆
Similar control is performed between the three stands.

FIG. 2 FTS is a professional diagram of the transfer function display for tension control between the above-mentioned φ1 to ◆2 stands.

In FIG. 2, the transfer functions correspond to the force control devices in FIG. 1, and 1 indicates the rolling mill drive motor l and its speed control device! The transfer function of the speed control system including the roll circumferential speed of +1 stand and the tension between ◆1 and 2 stands tf,
, is a transfer function of the tension generation mechanism showing the relationship between .

As is well known, the transfer function of the speed control device is expressed by a first-order delay cost equation. Here, 1+T1-8 T is a time constant, S is a Laplace operator, and K8 is a constant indicating a conversion coefficient determined by a roll radius or the like in a steady state.

Similarly, in the tension generation mechanism transfer function, the first-order delay is the tension generation dyne, and T4 is the time constant of tension generation. The tension control device consists of proportional and integral elements, that is, 1+T.・As shown in FIG. 2, the responsiveness and stability of the inter-stand tension control system depend on how the coefficient 71+T related to this proportional/integral element is determined.

Then, the coefficient T 1 * related to this proportional/integral element
Generally speaking, these are referred to as the control dynes of the inter-stand tension control system, but usually the leading element term (1+T*・S)#'i, which is the numerator term of the proportional/integral element of the tension control 1116, and the speed control system Since the delay element is compensated for, it comes down to how to determine the value of T1 among the proportional and integral elements of the tension control device.

Therefore, the control dynes of the inter-stand tension control system and rJ-1
In the following, I will simply refer to T1 as a representative of jealousy. Now, if the intersecting angle frequency of the loop representing the desired responsiveness of the inter-stand tension control yarn is Wc, F, then the second
Oven roux from the picture! One round transfer dyne is 3-4/
This is because Tt. From this equation (1), the control r in TsFi is determined by the following equation.

In the above equation, K is a constant as shown earlier, so the control gain T1 depends on the tension generation gain of the tension generation mechanism transfer function A with a cage of 4, and if 4 is found for this tension generation dyne, then ,
Desired crossing angle frequency We + of the tension control system between stands
A control gain T1 that satisfies F is obtained from equation (2).

On the other hand, conventionally, the control gain TI has been determined and set based on operational experience. In addition, in recent years, with the spread of computers, one computer has been used to calculate the above tension generation gain by 4 for each material to be rolled.
Some studies have also been conducted to calculate the value of Therefore, stand opening force control has been implemented.

[Key points of background technology]

However, conventionally, the rolled material passes through the stands of a continuous rolling mill from stand 1 to KOE, and the material spreads over many stands, causing tension interference between each stand, etc., and the controllability remains constant. It is known that if this happens, the inter-stand tension control system becomes unstable. This means that the tension generation gain in the l/g2 diagram changes by a factor of 4 each time the material passes through the stand, but no particular measures have been taken in the past regarding this point.

[Object of the invention].

The present invention has been made with attention to the above points, and its purpose is to stabilize a continuous rolling mill with three or more stands that can contribute to improving product dimensional accuracy and stabilizing operations by stabilizing inter-stand tension control. An object of the present invention is to provide a method for controlling tension between stands.

[Summary of the invention]

In order to achieve the above object, the present invention clarifies that the tension generation dynes change as the rolled material passes through the stands one after another, and the control of the tension control device changes each time the rolled material passes through the stands one after another. The present invention is characterized in that the tension between the stands can always be controlled stably regardless of the number of stands in which the rolling material is spread across the continuous rolling mill.

[Embodiments of the invention]

An embodiment of the present invention shown in the drawings will be described below.

ME will explain the present invention in detail, and it will be made clear that the focus of the present invention is that the tension generation gain changes each time the rolled material passes through each stand of the continuous rolling mill. To this end, we will discuss the general formula for the inter-stand tension generation mechanism of a single-mass continuous rolling mill.

Figure 3 shows an arbitrary stand of a continuous rolling mill and its front edge stand. In the figure, J is the rolled material, x
Fi is the rolling mill of each stand. Now, paying attention to the tension tf, i between ÷1~+1+1 stands, the tension tf, t is the material speed (personnel speed) on the entry side of the i+1 stand Vrs, t
+t and φil stand exit side material speed (material output speed) VOU
The relationship between T and i is expressed by the following equation.

Here, E: Young's modulus of material; LS; Φt~◆1+1 distance between stands.

This formula (1) is expressed as 7. In the relational expression based on the law of , (2)
It can also be expressed as an expression.

Here, tf, i/ri distribution is shown.

Na i + 1 stand's personnel speed "N + 1 + 1, Na fish stand's output speed VOUT, i is VxN, s from rolling theory
+t=Wt+1・X1+1・(1+ft+1)...
(3) youT, t == W 1・(1+f1)
... is represented by (4).

Here, Wl; roll circumferential speed of stand i, Wi+1
: +i +l roll circumferential speed of stand, fm
; Advanced rate of φl stand, fl+t ; Advanced rate of φ1+1 stand, Xl++
; φi+1 Inlet side material cross-sectional area of stand (Aovt,
By substituting equations (3) and (4) into equation (2), the following equation is obtained.

...(5) In this equation (5), if we consider minute changes from the steady state, (
6) Equation becomes.

+W++ l° Δfl
+1 is (force), respectively, as shown in equation (8).

Δfi=kf, i・Δtf, 1−kbll・Δtfp
i 1 ... (force Δfi+t=kf, i+
t HΔtf, l+1−kb, l+1°Δtf, i
Effect coefficient between °-+81 and advanced rate, kb, sVi++
This is the coefficient of variation between the rear tension of the stand tb, r (=tr, s-t) and the advance rate. And this (7), (
By substituting equation (8) into (6), the following equation is obtained.

Δ” ” ” ” l, 1 ” (Wi+1 ′ X1
+, °kf, l+1°Δtf, l+1-(Wi publication'
Xi+1'kb, l+1+W1'kf, i) Δtf, i
+Wi'kb, iΔtf, i-1+X1+1゜(1+f
1+t)-Δ, Wt+t (1+f!MW1)...
(9) After all, this equation (9) is a general equation showing the ykI relationship between the change in the roll peripheral speed of each stand and the change in tension between the stands. In addition, in this equation (9), the variables without the symbol Δ, which represents a minute change, are the steady state forces, and if the type of rolling material and rolling schedule are known, it can be calculated in advance for each rolling material. It is direct that can be decided.

Next, the focus of the present invention, that is, the visual image when the rolled material passes through the stand in sequence, will be explained as described above.
:, (This will be explained using Equation 91 and FIG. 4.

Figure 4 shows a continuous rolling mill with a four-stand configuration.
This figure shows how the rolling mill 1 passes through the rolling mill 1 in sequence.

In the figure, state (Ta) is the state in which the tip of the rolled material J is caught in the +2 stand, state (Tb) is the state in which the tip of the rolled material J is caught in the third stand, and state (Te) is the state in which the tip of the rolled material J is caught in the +2 stand. Each shows a situation in which the lost ground is bitten by a +4 stand. This each state withered (Ta) ~ (
Te), the relationship between the tension tLl between ÷1 and φ2 stands and the roll chest speed of one stand is shown below.

First, the material is spread over two stands (T
Consider a). In the case of T114 (Ta), the rear tension of the +1 stand and the +17] tension of the +2 stand are zero, and the speed of the +1 stand is changed without changing the roll circumferential speed of the +2 stand. Then, the circumferential speed of the roll in the first stand #f and the tension between the two stands tf.

Expressing the relationship with , four holes can be obtained from equation (9).

=a■・Δtf, 1+b11・Δwl ・・・α
Moan... αυ bu ;-L, (1+fi) ・”
Q3 If we set the left side of this 001 formula to zero, the state (Ta)
Roll peripheral speed Δw of one stand! Tension between Toner 1 and 2 stands Δtf, steady r in tx (Ta)
is obtained. In other words, this steady r ingr (Ta) is the state (Ta)
This corresponds to 1 for the tension generation mechanism transfer function in FIG.

Next, the material is spread over three stands (T
Consider b). The relationship between the inter-stand tension and the roll circumferential speed in this state is expressed by the state equation of Equation 04 from Equation (9).

...04J Formula 1 is the general formula (9), with l=1 for the force between stands Na1 and S2, and i=2 for the tension between stands Na2 and S3. Substitute, +1 stand rear tension tf, 0
This is an equation obtained by substituting the forward tension If of the 0 and +3 stands and the amount of change in roll circumferential speed ΔW3 of the 3=O and +3 stands ΔW3=0.

From formula Q4), the amount of change in roll circumferential speed ΔW for +1 stand
The steady-state gain g1 (tb) of the transfer function showing the relationship between 1 and the tension between the 1 and 2 stands Δtf, 1 is as follows.

Comparing Equation 0'5 and Equation 07), it is clear that the state Th(Ta) (the material straddles two stands) and the state (Tb) (the material straddles three stands) The change in tension iL' (steady gain) between ◆1 and 2 stands for the change in roll strength speed of +1 stand is different between (17
)0 * aH (because U), so the state (T
b) has a larger steady-state gain, gt (Tb) > gx (Ta) ・
(According to the relationship 18. This means that the tension generation gain (=steady gain) K between the tension generation mechanism transfer functions in Figure 2
1 means that it increases each time the material passes through the stand.

Using the same method, the relationship between the inter-stand tension and the roll circumferential speed for the state u(Tc) can be found using equation (9), α1
The formula becomes

... (To) The above formula (11) is obtained from the general formula (9) using the same concept as when calculating formulas 0I and 1. In other words, the rear tension Δtf of +1 stand is , o =
0, +4 stand forward tension Δtf, 4=0.4w4=
This is an equation obtained under the condition o.

From this (15 fist equation), the steady gain (tension generation gain) gs (To) in state (Tc) K becomes,
As is clear from the above aken formula, a7) formula, and the four holes, gt (Tc) > gx (Tb) >
The relationship is tx (Ta) - c2.9,
It is shown that the tension generation dynes increase as the material passes through the stands in sequence and the number of stands spanned by the material increases.

This means that the tension generation gain shown in Figure 2 changes by 1 each time the material passes through the stand, so if the control gain of the tension control device is constant, the response of the inter-stand tension control system will change. This means that sometimes vibrations occur.

FIG. 5 shows the configuration of an embodiment of the method of the present invention, and the figure shows the configuration of a continuous rolling mill with four stands. In FIG. 5, the same parts as those in FIG.

In the figure, 9*10 is equipment for realizing the method of the present invention,
This is a material position detection device that detects the position of the rolled material attached to each stand, and the material position information (Ti) detected by the conventional load relay @10Fi material position detection device @S. Load the book into the tension control device f1
This is a control one-dyne calculation device that calculates the control gain of each tension control device and outputs the total value jIL to each tension control device.

Moreover, we, i' are the crossing angle frequencies of the desired inter-stand tension control system described above. Furthermore, L! is a calculator that calculates settings for continuous rolling mills, and for each rolling material, [stock],
The constants a1t to ass*btt to b33 of the 12υ formula are calculated in advance, and their baskets are given to the control 1-dyne arithmetic unit f& in advance.

Next, the present invention will be explained in detail using the configuration of an embodiment of the present invention shown in FIG.

First, +1 to +2 stand expansion force control will be described. First, tension between the stands does not occur until the rolled material J bites into the two stands. Therefore, by the time the material J is bitten into the +2 stand, the control gain calculation device 10 of the φl stand has been given in advance by the td meter 11.
cm, G! l) Using the formula of each constant, calculate the tension generation amount in using the Oken formula, and based on this calculation, calculate the +1 stand control gain using formula (2), and set it on the tension control device. In other words, as shown in FIG. 4, the state is initially (T&), so 1. The tension generation gain in this state b(T&) is calculated using equation 03 (2).
Calculate and set the control gain using the formula. When the rolling material is applied to the +2 stand, the tension control between the first and second stands of the initially set control dynes is performed as explained in the conventional method shown in FIG.

Next, when the rolled material J is applied to the third stand, the tension generation gain changes as described above.

Therefore, the present invention optimally changes the control gain of the inter-stand tension Il+ control system based on the timing when the material J is bitten into the +3 stand. That is, when the material J bites into the +3 stand, the material position detecting device detects the material biting timing and outputs the material biting signal TI to the control gain calculation device 10. In addition, the control gain calculation device 1
0 receives the H material biting signal Ti, and at the same time calculates the tension generation gain when the material is running between three stands with aη2, and calculates the calculated value and the intersection angular frequency We.
, F based on equation (2), and outputs it to the tension control device. As a result, it is clear that stable inter-stand tension control is performed under the control gain changed above from the time the material J bites into the 3rd stand until the material J bites into the +4th stand.

Next, when the rolled material J is bitten by 4 stands, a is also used in an intermediate way, that is, in this case, it corresponds to the shape track (Tc) in Fig. 4, so the tension calculated using equation (2) is The control gain may be calculated and set based on the generated gain using equation (2).

1:'vHl, the rolled material J passes through the stands one after another, and the material position detection device 2 detects whether the rolled material J is caught in the stand each time the number of stands where the rolled material 1 is spread over the continuous rolling mill changes. The control gain calculating device 10 detects the timing, and based on the timing, calculates an appropriate gain according to the number of stands where the rolled material J is spread over the continuous rolling mill, and the tension control device f! It is clear that by mutually changing the settings of jt, stable and strong inter-stand control can be achieved at all times.

Note that the present invention is not limited to the above embodiments.

(1) In the above, tension control between the Na1 and So2 stands was explained, but the tension control between +2 and ÷33. The same goes for the tension control between the stands. In other words, in the tension control between Na2 and ÷3 stands, the control gain of the two stands is calculated and set in advance by the control gain of the two stands. Then, after the material J is placed in the four stands, the control 41 dynes of the two stands are sequentially changed based on the signals from the material position detection devices (2) In the above,
Although the case where the leading edge of the material J passes through each stand is shown, the control gain is similarly changed using the configuration shown in FIG. 5 also in the case where the rear end of the material 1 passes through the valley stands. That is, when the rear end of material J passes through the 1st stand, the tension control between φ2 and φ3 stands and the tension control between φ3 and φ3 are performed.
In the inter-stand tension control, since the stand on which the material J wants to attach changes, the control gain may be changed in accordance with the changed number of stands.

(3) Although the continuous rolling mill with /fi4 stand configuration is shown in FIG. 5 above, it is clear that the method of the present invention can also be applied to a configuration with three stands or four or more stands. It is also clear that the present invention can be applied to an inter-stand tension control device using a looper or the like. Furthermore, the desired inter-stand tension control system's intersecting angular frequency We, FI
J. It may be different for each stand.

〔Effect of the invention〕

As explained above, according to the present invention, the control gain of the tension control device is optimally changed based on the tension generation gain that changes each time the side slope passes through a stand. It is possible to provide a method for controlling tension between stands of a continuous rolling mill, which can stabilize tension control between stands of a continuous rolling mill, improve product dimensional accuracy, and realize stable operation.

[Brief explanation of drawings]

Figure 1 shows the conventional tension control method between stands. Figure 2 is a diagram showing the inter-stand tension control system, Figure 3 is a diagram showing an arbitrary stand of a continuous rolling mill and the stands before and after it, and Figure 4 is a diagram showing the tension control system between the stands. FIG. 5 is a block diagram showing an embodiment of the present invention, which is a diagram for explaining that the tension generation gain is changed as the stand passes through the stands. DESCRIPTION OF SYMBOLS 1... Material to be rolled, 2... Rolling machine, 3... Rolling machine drive motor, 4... Speed control device, 5... Tension detection device, 6... Tension control device, 7. ... Speed control system transfer function, 8... Tension generation mechanism transfer function, 9... Material position detection device, 10... Control r-in calculation device, 1 No.
・ynn machine, tf, i...su quantity ~su i+1 stand opening tension, t4gr, 1...su quantity ~ target tension between nato stands, ΔN1... output of su quantity stand tension detection device mutual Signal 1SBEF,... Speed standard of φ1 stand, ΔW... Amount of roll circumferential speed correction amount of stand, vo
υT+1...◆i quantity stand exit side material speed, VIN,
i+1...φi+1 stand entrance side material speed, Ti・
・・Material position detection device for pull stand! The output signal of We
, F...Cross angle frequency of the inter-stand tension control system. Applicant's agent Patent attorney Takehiko Suzue 1st Zurin 1 Stan R Bed 2 Stand
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A continuous rolling mill with an m-stand (m is an integer of 3 or more) configuration, which is equipped with a tension control device that controls the tension between each stand to a desired target value, and a material position detection device that detects the position of the material to be rolled. , the material position detection device detects the timing at which the tip and rear end of the oblique side to be rolled sequentially pass through each stand of the continuous rolling mill, and the control dynes of the tension control device are changed at each detected timing. 1. A method for controlling tension between stands of a continuous rolling mill, characterized in that the i-force between the stands is controlled by