JPH07155817A - Method for controlling tension of continuous rolling mill - Google Patents

Abstract

PURPOSE:To improve tension control accuracy, and to improve dimensional accuracy by calculating a torque arm variation with no tension according to the variation of a rolling load, and calculating the corrected value of the torque arm with no tension of a stand on a posterior stage side. CONSTITUTION:When controlling tension between an i + 1 stand 1c and an i + 2 stand 1d, the rolling load of an (i) stand 1b just after a rolling stock is bit, and the rolling load of an (i) stand 1b made no tension state at the time of the lock-on timing of the torque arm with no tension of the (i) stand 1b, are temporarily stored. A torque arm variation with no tension of the i + 1 stand 1c, is calculated according to the variations of these rolling loads and the influence coefficient of the torque arm with no tension. The correction value of the torque arm without tension of the i + 1 stand 1c, is calculated. Consequently, even in the case of the rolling of a special steel with a large rolling load, tension with high accuracy, can be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension control method for a continuous rolling mill, which enables highly accurate tension control even when rolling alloy steel or the like having a high rolling load.

[0002]

2. Description of the Related Art When rolling a rolling material by a hot tandem rolling mill having a plurality of stands, the tension of the rolling material between the stands is controlled by a tension control device. In the conventional tension control device (torque load memory system), the ratio G / P between the rolling load (P) and the rolling torque (G), that is, the torque arm is always a constant value in the longitudinal direction of the rolled material. Tension control was performed.

[0003]

However, when rolling a special steel having a large rolling load, the portion supported by the skid of the heating furnace (hereinafter referred to as skid mark) is rolled on the roll of each stand. Then, the rolling load fluctuates, and the torque arm does not show a constant value. Therefore, in the conventional tension control device that calculates the tension over the entire length of the rolled material with the torque arm set to a constant value, the tension calculation error accumulates, and accurate tension control cannot be performed for all types of rolled material. There is a problem to be solved that there is a possibility that the rolled material may break due to poor dimensional accuracy of the material or momentary excessive tension.

Therefore, the present invention has been made in view of the above circumstances, and provides a tension control method for a continuous rolling mill capable of performing highly accurate tension control even for a special steel having a large rolling load. The purpose is to do.

[0005]

According to the tension control method for a continuous rolling mill of the present invention, the rolled material is the i-th stand, i + 1.
In the tension control method of the continuous rolling mill, in which the rolling is continuously performed on the (i) th stand and the (i + 2) th stand, and a predetermined torque arm value is set in the rolling material between the stands to control the tension, Based on the rolling load fluctuation amount, which is the difference between the rolling load when the tip of the rolled material bites into the stand and the rolling load when the rolled material bites into the i-th stand in a tensionless state Calculate the torque arm fluctuation amount. Then, a correction value of the tensionless torque arm of the i + 1-th stand on the rear stage side is calculated based on the calculated variation amount of the tensionless torque arm.
This is a method of controlling the tension between the i-th stand and the (i + 2) th stand.

[0006]

According to the tension control method of the continuous rolling mill of the present invention, the rolling load when the rolled material is caught in the i-th stand on the preceding stage side and the rolling load at the lock-on timing of the i-th stand. Is stored, and the tensionless torque arm fluctuation amount is calculated based on these rolling load fluctuation amounts, and based on this tensionless torque arm fluctuation amount, the tensionless torque arm of the i + 1-th stand on the rear stage side is calculated. By performing the method of calculating the correction value of, even if the rolling load largely changes due to the arrival of the skid mark portion on the roll of each stand, the fluctuation of the tensionless torque arm of the (i + 1) th stand can be reliably corrected. be able to. Therefore, even when rolling a special steel having a large rolling load, the accuracy of tension control between the i + 1st stand and the i + 2nd stand is improved, and the dimensional accuracy can be improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the tension control method for a continuous rolling mill according to the present invention will be described below with reference to FIGS. FIG. 1 is an example of a torque memory type tension control device used for carrying out the present invention, and is an explanation showing the timing from the state in which the tip of the rolled material 1 is caught in the i stand to the start of tension control. It is a figure and the code | symbol 1a-
1d is a stand, 3a to 3d are electric motors, 5a to 5d are electric motor drive devices, and 7a to 7d are load detectors that detect the load during rolling of each stand. Further, reference numeral 10 in FIG.
The timing at which the tip of the rolled material 1 that has moved from the (i-1) th stand (i-1 stand) 1a bites into the i stand 1b (hereinafter, referred to as rolling timing 10), and reference numeral 11 denotes the rolled material 1. The timing (lock-on timing) for collecting the data of the _tensionless torque arm a _Oi of the i-stand 1b that is biting in the tensionless state (hereinafter referred to as rolling timing 11) is indicated by reference numeral 12.
Indicates the start timing for calculating the tension between the i stand 1b and the i + 1st stand (i + 1 stand) 1c (hereinafter, referred to as rolling timing 12), and the reference numeral 13 indicates
The timing for performing correction control of the tensionless torque arm of the i + 1 stand 1c in the tensionless state (hereinafter,
It is called rolling timing 13. ).

The present embodiment is characterized in that the tensionless torque arm of a predetermined stand is calculated and corrected. The torque arm calculation method will be described with reference to the block diagrams of FIGS. 1 and 2. . First, when the rolled material 1 bites into the i stand 1b (rolling timing 10), the relay 10R is turned on by the control signal I _R1 output from the control unit (not shown), and is detected by the load detector 7b. The rolling load Pi of the i-stand 1b immediately after the rolling material 1 is bitten is stored in the memory 15 as the delay load P _Di. This delay load P _Di is i + 1 stand 1c
It is used as control data. Further, the rolling torque Gi detected from the electric motor drive device 5b is also stored in the memory 15.

Next, at the lock-on timing of the _tensionless torque arm a _Oi of the i-stand 1b (rolling timing 11), the relay 11R is turned on by the control signal I _R2 output from the control unit, and the load detector. The rolling load Pi of the i-stand 1b in the tensionless state detected in 7b is stored in the memory 1 as the lock-on memory load P _Mi.
6 is stored.

Next, i stand 1b and i + 1 stand 1
At the start timing for calculating the tension between c (rolling timing 12), the relay 13R ₁ is turned on by the control signal I _R3 output from the control unit, and based on the delay load P _Di and the memory load P _Mi , The load variation amount ΔPi is calculated by the following equation. ΔPi = P _Di −P _Mi (1) This calculation result ΔPi is stored in the memory 18.

Then, based on the load variation amount ΔPi of the formula (1) stored in the memory 18 and the tensionless torque arm influence coefficient (∂a _{oi + 1} / ∂Pi) stored in the memory 19 in advance, The variation amount Δa _{oi + 1} of the _tensionless torque arm of the i + 1 stand 1c is calculated by the following equation. Δa _{oi + 1} = ΔPi · ∂a _{oi + 1} / ∂Pi (2) The calculation result Δa _{oi + 1} is stored in the memory 20.

Then, based on the tensionless torque arm fluctuation amount Δa _{oi +1 of the} formula (2) stored in the memory 20, and the uncorrected tensionless torque arm value a _{Oi + 1} stored in the memory 17, The correction value A _{Oi + 1 of the tensionless} torque arm of the i + 1 stand 1c is calculated by the following equation. A _{oi + 1} = a _{oi + 1} + (∂a _{oi + 1} / ∂Pi) · ΔPi (3) This calculation result A _{oi + 1} is stored in the memory 21 and stored in the tensionless torque arm of the i + 1 stand 1c. Used as correction control.

The control signal I from the control unit_R3Is output
If not, that is, before rolling timing 12, relay 1
3R₁Is turned off and the relay 13R₂Is ON
The load of zero value output from the memory 22 after being put in the state
The heavy fluctuation amount ΔPi is stored in the memory 18, and therefore
Correction value A of the tensionless torque arm of i + 1 stand 1c
_{Oi + 1}Does not change from the value before correction.

Next, the torque arm calculation method of this embodiment will be described.
Used i + 1 stand 1c and i + 2nd stand
(I + 2 stand) Tension control procedure between 1d and rolling
Please refer to the flow chart in Figure 3 that corresponds to the timing.
Explain. In addition, in this embodiment, a special rolling load is large.
Since we are rolling steel, the arrival of the skid mark part
The delay load P detected by the i stand 1c_Dias well as
Lock-on memory load P _MiVaries as shown in FIG.
ing. In addition, i-1 stand 1a and i stand 1b,
Tension control between i stand 1b and i + 1 stand 1c
Has already been performed using the torque arm calculation method of the present embodiment.
It is assumed that

First, in step S1, the rolling load Pi of the i stand 1b is stored as the delay load P _Di. Next, in step S2, the _tensionless torque arm a _Oi of the i stand 1b is calculated by the following equation as the average value of N _ao . Here, N _ao is the number of samplings of the tensionless torque arm a _Oi , δi is the rear tension influence coefficient of the i stand 1b, and t
_i-1 is the tension between the i-1 stand 1a and the i stand 1b.

Further, in step S3, the rolling load Pi of the i stand 1b is stored as a lock-on memory load P _Mi. Next, in step S4, the difference between the delay load P _Di and the memory load P _Mi , that is, the load variation Δ
Calculate Pi. Then, in step S5, the load variation amount ΔPi and the tensionless torque arm influence coefficient (∂a
_{Based on oi + 1} / ∂Pi), the tensionless torque arm fluctuation amount Δa _{oi + 1} of the i + 1 stand 1c is calculated. Further, in step S6, the tensionless torque arm fluctuation amount Δa _{oi + 1}
Then, the correction value A _{Oi + 1} of the _tensionless torque arm of the i + 1 stand 1c is calculated based on the uncorrected tensionless torque arm value a _{Oi + 1} stored in the memory 17.

Further, in step S7, i + is calculated based on the calculated correction value A _{Oi + 1} of the _tensionless torque arm.
After the tension t _{i + 1} between the 1st stand 1c and the i + 2 stand 1d is calculated by the following equation, _{i + 1} is calculated in step S8.
The tension between the stand 1c and the I + 2 stand 1d is controlled. t _{i + 1} = (A _{oi + 1} · P _{i + 1} −G _{i + 1} −δ _{i + 1} · t _i ) / γ _{i + 1} (5) where γ _{i + 1} is the i + 1 stand Forward tension influence coefficient,
δ _{i + 1} is an i + 1 stand rear tension effect coefficient.

Therefore, in this embodiment, when the tension between the i + 1 stand 1c and the I + 2 stand 1d is controlled, the rolling load Pi (delay load P _Di ) of the i stand 1b immediately after the rolling material 1 is bitten into , The rolling load Pi of the i-stand 1b in the tension-free state at the lock-on timing of the tension-free torque arm a _Oi of the i-stand 1b.
(Lock-on memory load P _Mi ) is temporarily stored, and the i + 1 stand is based on the rolling load fluctuation amount (load fluctuation amount ΔPi) and the tensionless torque arm influence coefficient (∂a _{oi + 1} / ∂Pi). 1c tensionless torque arm fluctuation amount Δa
_{Since oi + 1} is calculated and the correction value A _{Oi + 1} of the _tensionless torque arm of the i + 1 stand 1c is calculated, the rolling load is increased by the arrival of the skid mark portion on the roll of each stand. Even if there is a large change, it is possible to surely correct the change in the tensionless torque arm, and therefore it is possible to perform tension control with high accuracy even when rolling special steel or the like having a large rolling load.

[0019]

As described above, according to the tension control method for the continuous rolling mill of the present invention, the rolling load when the rolled material is bitten into the i-th stand and the lock-on timing of the i-th stand. The rolling load at that time is stored, the fluctuation amount of the tensionless torque arm is calculated based on the fluctuation amount of these rolling loads, and the i + 1-th stand on the rear stage side is calculated based on the fluctuation amount of the tensionless torque arm. Since the method of calculating the correction value of the tensionless torque arm is performed, even if the rolling load fluctuates greatly due to the arrival of the skid mark portion on the roll of each stand, i +
It is possible to reliably correct the tensionless torque arm fluctuation of the first stand. Therefore, even when rolling a special steel having a large rolling load, the tension between the i + 1st stand and the i + 2nd stand. It is possible to improve control accuracy and achieve improvement in dimensional accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a non-tension torque arm lock-on timing of an example of a torque memory type tension control device used when implementing the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a torque memory system control device.

FIG. 3 is a flowchart showing a procedure of a torque arm calculation method according to an example of the present invention.

FIG. 4 is a diagram showing a rolling load that fluctuates during rolling.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Rolled material 1a i-1st stand 1b i-th stand 1c i + 1st stand 1d i + 2nd stand 3a, 3b, 3c, 3d electric motors 5a, 5b, 5c, 5d electric motor drive devices 7a, 7b, 7c, 7d. Load detector 10 Timing of rolled material biting into i-th stand 11 Data acquisition timing (lock-on timing) when i-th stand is a tensionless torque arm 12 Tension calculation timing 13 Tension control timing P _Di i-th Delay load of stand P _Mi Lock-on memory load of i-th stand ΔPi i Load fluctuation amount of i-th stand Δa _{oi + 1} i + 1 No-tension torque arm fluctuation of stand 1c A _{Oi + 1} i + 1 No-tension torque arm of stand 1c Correction value of

Claims (1)

[Claims] 1. A continuous rolling method in which rolled material is continuously rolled on the i-th stand, the (i + 1) th stand, and the (i + 2) th stand, and a predetermined torque arm value is set for the rolled material between the stands to control tension. In the tension control method for a rolling mill, the rolling load when the tip of the rolled material bites into the i-th stand and the rolling load when the rolled material bites into the i-th stand in a tensionless state The tensionless torque arm fluctuation amount is calculated based on the rolling load fluctuation amount which is the difference, and i + on the rear stage side is calculated based on the tensionless torque arm fluctuation amount.
A tension control method for a continuous rolling mill, comprising performing a tension control between an i + 1st stand and an i + 2nd stand after calculating a correction value of the tensionless torque arm of the first stand.