JPH01306009A - Method and device for controlling tension between stands in continuous rolling mill - Google Patents

Abstract

PURPOSE:To improve the product quality and operational safety by learning a speed ratio of electric motors per material based on an average speed of driving electric motors under a stable condition and setting respective speeds of both motors so that a preceding learning value and a present learning value are equal. CONSTITUTION:Respective speed controllers 5, 6 for driving electric motors 3, 4 in stands #1, #2 are installed and a speed setter 10 setting speeds of both the motors 3, 4 is also installed. When the #1 stand starts rolling, a tension controller 7 stores a ratio K1=G1/P1 of a rolling load P1 and a rolling torque G1. When a stock Z is rolled by the stands #1, #2, a tension deviation DELTAtf is inputted to the setter 10 and the setter 10 sets speeds of the motors 3, 4 so that the preceding and present learning values of the motors 3, 4 are equal. Hence, the product quality and operational safety are improved because a deviation from a speed ratio under a stable condition is kept a small value.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention provides a method for driving two adjacent stands so that the tension applied to the material to be processed becomes a predetermined target tension value. The present invention relates to a method and device for controlling tension between stands of a continuous rolling mill that controls the speed of an electric motor.

(Prior Art) In the above-mentioned continuous rolling mill, fluctuations in tension between stands not only cause fluctuations in product/J' method, but excessive fluctuations in tension may even cause material breakage accidents.

Conventionally, in the inter-stand tension control of a continuous rolling mill that rolls wire rods and steel bars, the inter-stand tension is calculated from the rolling load and rolling torque, and the calculated tension is used as the target tension. A method has been adopted to control the tension between the stands by adjusting the speed to match the

Before explaining the control principle of this control method, the basic rolling equation in a state where a material is being rolled will be explained.

The material is l stand (1st stand) and (i+1
) The pre-rolling ff1P and rolling torque G of the l stand in the state of rolling on the stand are expressed as follows.

2°-P, '``l'i-βi''bir
+, o I... (1) CI・"G1.o-γi"1rI-δI"bi...
(2) Here, P: Rolling load when the l stand is under no tension 1.0 G: Rolling torque when the l stand is under no tension 1.

jrI: forward tension t of l stand 2 rearward tension αl of i stand: influence coefficient β representing the degree of influence of front tension tri on rolling 6f load, : influence coefficient γ representing influence degree of rear tension tb□ on rolling load , : Influence coefficient δ representing the impact of front tension t'l on rolling torque, : Influence coefficient representing impact of rear tension tbl on rolling torque Influence coefficient α of equations (1) and (2) above ,,β1゜γI
, δ1 are constants determined by the material and rolling machine.

Here, if the ratio of rolling torque to rolling load during tensionless rolling is k, -G. /P. ...(3)(
When formulas (1) and (2) are substituted into formula 3), the ratio of rolling torque to rolling load is expressed by the following formula.

k ″(G,,o−γi′tI′i−δl′″bl)÷
(Pi, o-α1・trI-β1・' bl)...
(4) From equation (4), 1 is the ratio of rolling torque to rolling load during tension-free rolling of l stand, and rolling load P1 and rolling torque G1 of l stand at any time. In addition, it can be seen that if the front tension t,1 and the rear tension tbl are known, it can be obtained.

Expressing equation (4) with respect to the forward tension trl, t rl−
(k t ” P s −G ]+t number (k t
・βi+δI))bi ÷ (γ, -k ・α,) ... (5
)+I+.

Equation (5) is the ratio of rolling torque and rolling load when no tension is applied,
It is shown that if is detected and memorized when there is no tension, the front tension t of one stand can be calculated from the rolling load P1, the pressure ('1), the rolling torque G, and the rear tension tb+ from time to time. There is.

The above equations (1) to (5) are basic equations for determining the forward tension from the rolling torque and rolling load.

A conventional tension control method between stands in a continuous rolling mill for wire rods and steel bars using this basic formula will be explained with reference to FIGS. 4 and 5.

FIG. 4 is a rolling state diagram for explaining a conventional inter-stand tension control method, and shows a two-stand configuration of #1 stand 1 and #2 stand 2. In Figure 4, 81 shows the state in which the material 2 is caught in the #1 stand 1, and 82 shows the state in which the material 2 is also caught in the #2 stand 2.
shall be.

Now, considering the state S1 in which the material Z is caught in the #1 stand l, the material Z is not caught in the #2 stand 2, so neither the forward tension tri nor the rear tension tbi is acting on the material Z. It is in a state of tension. Therefore, the rolling load P and rolling torque G1 of #1 stand detected in state S1 are (1).

In formula (2), t −0, t b 1-0, P, −P, . ...(6)G, -
G. ...(7).

Further, the ratio 1c between the rolling torque and the rolling load when no tension is applied to the #1 stand 1 is calculated from the equation (4) by -G between the rolling torque G detected in the state S1 and the rolling load P1. /P
, o-G, /P, . . . (8). This value is stored in memory.

Next, considering a state S2 in which the material is caught in the #2 stand 2, tension is generated between the #1 stand 1 and the #2 stand 2 due to the difference in speed setting between both stands 1 and 2. this#
The tension between #1 stand 1 and #2 stand 2 is (5)
Detected from the expression.

That is, in the case of #1 stand 1, the rear tension tb1 is zero, so in equation (5), t b l"" O.

i-1, t "1"" (kloPl-01) ÷ (γ □-k φα) ...(9),
The forward tension tr1 in state S2 is calculated.

If the target tension is tl and REF for the previous tension r1 detected by this equation (9), then the tension deviation Δ between #1 stand 1 and #2 stand 2 ["At,"t1 ．． i? IN, I? l”l
If the roll speed of #1 stand 1 is controlled using this tension, the tension t, 1 between #1 stand 1 and #2 stand 2 becomes the target tension 'z, +<b
++ can be maintained.

In the following, stand configurations of three or more stands are controlled in the same manner.

FIG. 5 shows a conventional tension control device to which the above method is applied.

Two stands, #1 stand 1 and #2 stand 2, are also shown in FIG. #1 stand 1 is driven by electric motor 3, and #2 stand 2 is driven by electric motor 4. The speed of the electric motor 3 is controlled by a speed control device 5,
The speed of the electric motor 4 is controlled by a speed control device 6. #
The #1 stand 1 and the #2 stand 2 are each provided with load detectors 8 and 9 that detect the rolling load PL. A tension control device 7 is attached to the speed control device 5.

A similar tension control device is also attached to the speed control device 6, but its illustration is omitted. FIG. 5 corresponds to state S1 in FIG. 4, and accordingly the speed control device 5,
Controlled by 6.

In this state, the tension control device 7 uses the load signal r'j L 0,000P output from the load detector 8 of the #1 stand 1, the voltage V1, the current ■1, and the speed N1 of the electric motor 3.
(Each detector is not shown)
Rolling 6f weight P when no tension is applied. and rolling torque G are detected, and 1 is stored in the ratio of these.

Next, when state S changes to state S2, the tension side ■ The rolling load P1 and pressure when tension is generated by the sub-device 7 The extended torque G, is detected above, p,v,.

■ Calculated from and N, the inter-stand tension tr1 in this state is obtained from equation (9), and as shown in equation (10), the difference 1, I? EI', that is, the tension deviation Δt, is calculated.

The tension deviation Δtr thus obtained is converted into a control output ΔN1 for correcting the roll speed of the #1 stand 1, and is output to the speed control device 5 of the #1 stand 1.

The speed control device 5 corrects the speed N1 of the electric motor 3 using the control output ΔN1 as a speed correction amount, and
The tension tr1 of the stand 2 is changed.

In operation in state S, the tension t1.1 is the target tension tl, R
This is repeated moment by moment until it becomes equal to E)'.

The above is an outline of conventional inter-stand tension control.

A conventional tension control device between stands in a continuous rolling mill for wire rods and steel bars has the following characteristics.

1) If there is an error Z in the speed setting of the electric motor that drives the rolling rolls of each stand, the speed of the electric motor 3 is corrected using the roll speed correction control output ΔN1 output from the tension control device 7 shown in FIG.

2) The rolling result is reset each time the rolling of the material is finished, and each time before rolling starts, a new speed setting value is calculated from the rolling schedule, and this value is used to set the speed of the electric motor.

(Problems to be Solved by the Invention) The conventional tension control method described above has the following problems.

1) If there is an error in the motor speed setting, it will take time for the tension between the stands to reach a stable state, resulting in parts of the product where the target tension is not achieved.

2) Since the current rolling results are not reflected in the next rolling, if there is a speed setting error in one mill in the same lot, the same error will continue to occur when rolling materials with the second grain or lower.

This No. 2 1-1 error problem is not a particular problem when the speed setting error is small, but when the error is large,
Since the tension is greatly changed by the control output output from the tension control device, there is a risk of material breakage. Therefore, conventional inter-stand tension control poses problems in terms of product quality and operational safety.

Therefore, even if there is an initial error in the speed setting of the drive motor, the present invention automatically corrects it from the next material to produce a higher quality product, and also suppresses tension fluctuations and prevents material breakage. It is an object of the present invention to provide a method and device for controlling the tension between stands of a continuous rolling mill, which can suppress such problems and ensure operational safety.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above-mentioned object 1-1, the present invention provides a method for driving both stands in a stable state in which the tension applied to the material to be processed between both stands is controlled within a predetermined control range. The speed ratio of the two drive motors is learned for each material in the same lot from the average speed of the motor, and the speed ratio of the two drive motors is learned so that the initial speed ratio of the current material is equal to the learned value of the speed ratio calculated for the previous material. The speed setting value is determined.

(Function) According to the present invention, a stable state in which the tension between two adjacent stands is controlled within a control range can be determined by calculation from equations (9) and (10) using a conventional inter-stand tension control method. The tension deviation signal for the target tension is input, and this tension deviation is compared with the tolerance value for tension control accuracy. If it is less than the tolerance value, it is considered a stable state, and the rolling conditions with the previous material are Comparisons are made by creating material count values in the same lot with one mouth in the same lot as a count value of 1, and if the count value is 1, it is determined that the conditions are different, and if the count value is 2 or more, the material count value is determined to be different. If so, it is determined that the conditions are the same, and based on these determinations, the calculation of the speed setting value and the calculation of speed ratio learning are performed. Therefore, according to the present invention, since the rolling results of the previous month's material are reflected in the rolling of the next material, speed setting errors can be corrected each time, producing higher quality products, and tension fluctuations can be reduced. It is possible to measure operational safety by suppressing material breakage accidents.

(Example) Hereinafter, the present invention will be described in further detail in the case of a rolling mill having a two-stand configuration with reference to FIGS. 1, 2, and 3.

First, in FIG. 3, parts that are the same as those in FIG. 5 or have the same functions are designated by the same numbers as in FIG. In the device shown in FIG. 3, the speed setting device 10 is an additional device part provided in accordance with the present invention with respect to the device shown in FIG. 5, and the configuration of other parts is different from that shown in FIG. None. The speed setting values NI,REr''N2.I?IEr' for the electric motors 3 and 4 obtained from the rolling schedule are manually input to the speed setting device 10. Speed N, speed N of electric motor 1714
2. Tension side 13 The difference between the inter-stand tension calculated by the tl device 7 and the target tension [, that is, the tension deviation1.
1? El' Δtr - the material count value A1 within the same mouth and the tension control start signal A2 are introduced. The tension control start signal A2 is derived from the tension control device 7.

FIG. 1 shows a calculation flow of a speed setting value performed by the speed setting device 10 of FIG. 3. In FIG.

The calculation method for the speed setting value in the apparatus shown in FIG. 3 differs depending on the material count value At within the same lot. Then, it is judged based on the count value A1 whether it is the material of the first wood in the lot (step 11), and if it is the material of the first wood, the rolling conditions or the material is different from the previous material, so
#1 stand 1 obtained from the rolling schedule of the material this time
Speed setting value N of motor 3 and #2 stand 2
#1 stand 12, R
For FP, N - NO 1, RRI' 1. RI':r''2''Yu'
If the count value Al is after the second grain (Step 13 "Yes"), the rolling conditions are the same as the previous material. Therefore, the speed setting value N of the electric motor 4 of #2 stand 2, which was obtained from the rolling schedule using the learned value of the speed melon ratio of the previous month I-1, is changed to the speed setting value N of the electric motor 4 of #2 stand 2, and the speed setting value N of the electric motor 4 of REF 2 is and #1 s2, R
The speed setting value N of the electric motor '3 of FP stand 1 is as follows: 1,
I? Determine r':P from equation (12) (Step 4).

N = N 1, l? EF 2.17IP"'j-1""2) However, j-1:1 to the material count value of 1 wood, the learned value of the speed ratio of 1 water. The speed setting value obtained in this way is: A speed setting IJN is sent from the speed setting device 10 to the speed control device 5 that controls the speed Nl of the electric fi 3 of #1 stand 1.
A speed setting value N is also obtained for the speed control device 6 that controls the speed N2 of the electric motor 1, R1:l'4 of the #2 stand 2. 6 speed 2,)? E
l' Inverse control device 5.6 controls the speed N1°N2 of the electric motors 3, 4 in such a way that the speed setpoint obtained, respectively 'j, is realized.

When the speed setting and roll opening degree setting of #1 stand 1 and #2 stand 2 are completed in this way, the material is then conveyed and rolling is started in #1 stand 1.

#] stand] When rolling is started, the tension control device 7 adjusts the rolling torque G1 and rolling load P1 in the non-tension state to the speed N1 and current 1 of the electric motor 3 of the #1 stand 1.
The rolling load P is determined from the voltage V1, the rolling G, and the load P detected by the load detector 8, and the ratio of the rolling torque G1 to the rolling load P, +<, =c, /P, is stored. The ratio of 1 to the memorized rolling torque G and rolling load P is #
It is used to calculate inter-stand tension +il when tension is generated in #1 stand 1 and #22 stand 2.

The material Z is rolled by the #1 stand] and then rolled by the #2 stand 2. When the material Z is caught between the stands 1 and 2, tension between the stands is generated. When this inter-stand tension is generated, the tension control device 7 calculates the rolling torque G1 and rolling 6:1 weight 1) 1 at the time when the tension is generated, and then (
From formula 9), the tension between the stands t in this rolling state,
Find 1. This inter-stand tension tI'l is then (10
), the deviation of the target tension t, that is, the tension force Δ
tr is 1i1? El' is determined and then converted into a control output ΔN1 for the speed N of the electric motor 3 of the #1 stand 1, which is output to the speed control device 5 of the #1 stand 1. When the control output ΔN1 is output, the speed control device 5 changes the speed N of the electric motor 3 of the #1 stand 1, and adjusts the inter-stand tension tr1 for one week.

The tension control device 7 outputs the control output ΔN, and at the same time outputs the tension (-difference Δt" and tension control start 1≦A2) obtained by calculation to the speed setting device 10.

The speed setting device 10 determines the tension deviation Δ[r and the tension control start signal A2, and both stands], the speed N of the electric motors 3 and 4 of 2, , N, , material count value A1 in the same lot.
As input data, a learned value is determined according to the calculation flow of the learned value of the quick melon ratio shown in FIG.

In FIG. 2, first, the determination is made based on whether the tension control start signal A2 output from the tension control device 7 is "ON-" (step 21), and if "Yes", the tension deviation output from the tension control device 7 is determined. Determine whether the absolute value 1Δt,l of Δ[ is within the tension control range (step 22)
.

The reason why the tension control start signal A and the tension deviation Δt are determined is to perform the calculation of the learned value in a stable state in which the inter-stand tension is controlled within the tension control range by the tension control device 7.

When it is determined that the rolling is in a stable state through the above two determinations, the detected speed N1 of both rolling machines 3 and 4. N2
From this, the speed ratio of the Ryoichi motive 3.4 used for calculating the learning value is calculated. Here, both speeds N, , N2 are not always constant even if the tension between the stands is stable, so the speed ratio is calculated from the average speeds N, N as Nl/N2 (step 23).

Next, a learning value is calculated. The calculation of the learning value differs depending on the input material count value A1 in the same lot. If the count value A1 is "1", that is, one mouth in the same lot, the learning value is initialized as follows. (Step 25).

K - (N/N) ... (13) (j-
1) + Matadashi, K: (j=I) learning value count value A of one mouth in the same lot! is 2 or more, that is, if there are two or more mouths in the same lot (step 26 "Yes"), the learned value is calculated as shown in equation (14) below (step 27).

K - (Nl/N2)・α (j) + (1-a) φK (j-■)... (14) However, K: j main mouth learning value (j) K: (j-1) Honguchi's learning value (j-1) α: Learning coefficient The learning value obtained in this way is the next material (j+1
When calculating the speed setting value of book [1], the learned value K of equation (12)
The speed setting value N of the electric motor 3 of #1 stand (j-1) 1 is determined.

1, R):F The above is an example in which the speed setting method of the present invention is applied to a rolling mill having a two-stand configuration.

As explained in detail above, if the material being processed is one material in a lot, the speed setting value obtained from the rolling schedule is used, and if the material is from the second grain onwards, the speed setting is obtained using the learned value. The speed is controlled using the value, and the tension is controlled depending on whether the material is from the first hole in the lot or from the second grain onwards.
Since learning values are initialized or learning calculations are performed and the results are reflected in the speed setting for the next rolling, product quality can be improved and operational safety can be achieved.

Although the above embodiments are for the case of two stands, the present invention can also be applied to a case where inter-stand tension control is performed in a rolling mill configured with three or more stands.

〔Effect of the invention〕

According to the present invention, the speed is set so that the speed ratio of the previous four materials and the initial speed ratio of the current material are equal, so as the material rolling progresses, the initial speed ratio and the inter-stand tension fall within the control range. The difference between the speed ratio and the stable state speed ratio controlled as follows becomes smaller, and dimensional fluctuations due to tension fluctuations at the leading end of the material can be reduced. Therefore, quality improvement and operational safety can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the calculation flow of the speed setting value in the device of FIG. 3, FIG. 2 is a flowchart showing the calculation flow of speed ratio learning in the device of FIG. A block diagram showing one embodiment, FIG. 4 is a rolling state diagram for explaining a conventional inter-stand tension control method, and FIG. 5 is a block diagram of a continuous rolling mill and a conventional inter-stand tension control device that controls it. It is. 1...#1 stand, 2...#2 stand, 3.4
...Electric motor, 5,6...Speed control device, 7...Tension control device, 8.9...6:1 double detector, 10...
Speed setting device. Applicant's agent Sato - Yube 1 Figure 2 Ward 1 Zutashido Ben 2 Sugeshito Figure 5

Claims (1)

[Claims] 1. An inter-stand tension control method for a continuous rolling mill that controls the speed of the drive motors of both stands so that the tension applied to the material to be processed between two adjacent stands reaches a predetermined target tension value. In this step, the speed ratio of the two drive motors is learned for each material in the same lot from the average speed of the two drive motors in a stable state in which the tension applied to the material to be processed between the two stands is controlled within a predetermined control range. The tension control between stands of a continuous rolling mill is characterized in that the speed setting values of the two drive motors are determined so that the initial speed ratio of the current material is equal to the learned value of the speed ratio obtained for the previous material. Method. 2. In an inter-stand tension control method for a continuous rolling mill, the speed of the drive motor of both stands is controlled so that the tension applied to the material to be processed between two adjacent stands becomes a predetermined target tension value. speed ratio learning means for learning the speed ratio of the two drive motors for each material in the same lot from the average speed of the two drive motors in a stable state in which the tension applied to the material to be processed is controlled within a predetermined control range; and setting value determining means for determining the speed setting values of the dual drive motors so that the initial speed ratio of the current material is equal to the learned value of the speed ratio obtained by the learning means for the previous material. An inter-stand tension control device for a continuous rolling mill featuring: