JP2824186B2 - Speed control method of wire finishing mill consisting of two block mills - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed fine wire finishing mill comprising two block mills arranged in series.
The present invention relates to control for compensating for a decrease in mill passage characteristics when the leading end of a material bites into a second finishing mill due to a speed change between the two mills due to a speed impact drop.

[0002]

2. Description of the Related Art FIG. 3 shows the construction of equipment after a finishing mill in a wire rod rolling line. The material 1 is rolled by a first finishing block mill 2 and further rolled by a second finishing block mill 4. Since the exit material speeds of the first and second finishing block mills reach as high as 60 m / s and 100 m / s, it is difficult to control the loop by installing a looper between the two mills. Therefore, a guide pipe is used between the two mills. Contact and tension rolling. Next, the water cooling tube 5 and the pinch roll 6
, Reaches the laying head 7 and is formed into a ring-shaped product 8.

[0003] First and second finishing block mills 2 and 4
Are power converters 2c and 4c having a speed control function.
Is driven via transmissions 2g and 4g which are directly connected to the electric motors 2m and 4m controlled by.

In order to perform tension rolling between the two mills, the peripheral speed of the first roll of the second finishing block mill 4 is set to be higher than the peripheral speed of the final roll of the first finishing block mill 2. The peripheral speeds of the first and second finishing block mill exit rolls are V1 and V2, and the material cross-sectional areas are S1 and S2,
When the read rate is a, V2 = (1 + a) · S1 / S2 · V1. Although the lead rate a is preferably small from the viewpoint of product quality, it is required to be about several% from the passage characteristic of the material tip, that is, the material permeability.

FIG. 4 shows first and second finishing block mills 2.
7 shows the change in roll peripheral speed during rolling of Nos. 4 and 4. The horizontal axis shows time t, the vertical axis shows the roll peripheral speeds V1 and V2 of the first and second finishing block mills by solid lines, and the roll peripheral speed references Ref1 and Ref2 by dotted lines. Times t1 and t2 are
This is the time at which the material bites into the first and second finishing block mills, at which time speed drops cause instantaneous speed drops ΔV1 and ΔV2. The period between t1 and t2 is a single finishing block mill single rolling period, and there is no effect between both mills. However, after t2, tandem rolling is performed by the first and second finishing block mills, and the impact drop ΔV
Numeral 2 acts to reduce the difference in roll peripheral speed between the two mills. When the impact drop amount is larger than the lead rate a, the roll is inverted and the first finishing block mill pushes the material into the guide pipe, making it impossible to roll.

As a method of compensating for the speed impact drop, a method of setting a lead rate equal to or higher than the speed impact drop can be considered. However, if the lead rate is too large, the product quality is deteriorated. Material breaks.

A common compensation method is to increase the speed by adding a speed correction signal corresponding to the amount of impact drop before the material bites into the mill, and to cut off the speed correction signal at the same time as the biting. Has been adopted.

FIG. 5 shows the change in roll peripheral speed when this compensation is performed. The actual speed impact drop amount is ΔV.
In contrast to 1 and ΔV2, the apparent velocity impact drop amounts are small as ΔV1 ′ and ΔV2 ′. In this case, the speed correction signal is a fixed value determined by the maximum impact drop amount.

Although not shown in FIG. 3, the timing of applying the correction signal is performed by the tracking HMD. Since this control is high-speed rolling, it is very difficult to control the timing of applying a speed correction signal, particularly the timing of turning off the signal.

[0010]

In the conventional compensation method,
It is necessary to control the timing that cuts the speed correction signal, and to optimize the impact drop correction amount by changing the speed impact drop amount of the mill depending on the material, speed, shape of the material tip, speed, biting condition, etc. . The present invention provides a method for solving the above two problems.

[0011]

The present invention is based on a completely different concept, whereas the conventional compensation method compensates for offset by performing speed increase correction corresponding to the speed impact drop amount. That is, before the material bites into the first finishing block mill, the speed control circuits of the first and second finishing block mills are switched from PI control to P control to delay recovery of the speed impact drop by the control circuit, This is a method in which the speed difference between the two mills when the material bites into the second finishing block mill is maintained by returning from the P control to the PI control again after passing through the second finishing block mill.

[0012]

FIG. 1 shows a change in roll peripheral speed when such control is performed. The horizontal axis shows time t, the vertical axis shows the roll peripheral speeds V1 and V2 of the first and second finishing block mills by solid lines, and the roll peripheral speed references Ref1 and Ref2 by dotted lines. As described above, PI control is performed until time t0 before the first finishing block mill material bites, P control is performed from t0 to time t3 after passing through the second block mill material, and PI control is performed after t3.
Control.

The change in speed at this time is such that the speed impact drop ΔV1 generated at the first finishing block mill material biting time t1 does not recover, and the second finishing block mill material biting at time t2 remains in this state. In other words, the second block mill is relatively corrected by the speed impact drop amount of the first block mill. The speed impact drop ΔV at this time does not recover either. Here, the speeds of both mills between t2 and t3 are determined from the roll peripheral speeds V1 and V2 corresponding to the respective roll peripheral speed references Ref1 and Ref2.
If the speed impact drop ratios ΔV1 / V1 and ΔV2 / V2 are the same, the speed ratio does not change except at the moment when the material bites into the second finishing block mill. Will be.

Here, in general, when the speed impact drop rate ΔV1 / V1 in the first finishing block mill is large, it can be estimated that the speed impact drop rate ΔV2 / V2 in the second finishing block mill is also large, and therefore t2 The compensation when the second finishing block mill material is caught between t3 and t3 is optimized according to the properties of the material.
By returning to PI control again after passing through the second finishing block mill, both mills are rolled at roll peripheral speeds V1 and V2 corresponding to the respective roll peripheral speed references Ref1 and Ref2.

[0015]

FIG. 2 shows a specific example of this control switching. The difference between the speed reference Ref and the speed feedback from the PLG for detecting the speed of the material is determined by the speed control circuit SC,
The power converter THY is controlled via the current control circuit CC and the voltage control circuit VC to control the speed of the motor. Here, the resistance R of the feedback circuit of the speed control circuit SC
And by opening and closing both ends of the capacitor C by the contactor X, the speed control circuit performs PI control.
Switch to control. That is, PI control is performed when the contactor X is opened, and P control is performed when the contactor X is closed. The contactor X is a material detection HMD1 installed on the entrance side of the first finishing block mill.
And material detection H installed on the exit side of the second finishing block mill
With MD2, it closes only during the period when the material tip passes between HMD1 and HMD2.

[0016]

According to the present invention, the control circuit switching timing is before the leading edge of the material bites into the first finishing block mill and after passing through the second finishing block mill. There is no switching at the moment of biting,
Very easy. Further, since the speed impact amount of the first finishing block mill becomes the correction value of the second finishing block mill, the correction amount is automatically optimized.

[Brief description of the drawings]

FIG. 1 shows a case where the present invention is applied. Roll peripheral speed v1 of a first finishing block mill of a high-speed thin wire finishing mill composed of two block mills and roll of a second finishing block mill.
6 is a graph showing a change in peripheral speed v2.

FIG. 2 is an electric circuit diagram showing one configuration of a power conversion device for implementing the present invention, and is a power conversion device 2 shown in FIG.
c, 4c.

FIG. 3 is a block diagram showing a line configuration of a high-speed small-diameter wire rod finishing mill including two block mills.

FIG. 4 is a graph showing an impact drop of a roll peripheral speed in a high-speed small-diameter wire rod finishing mill.

FIG. 5 is a graph showing a roll peripheral speed when a conventional impact drop compensation is performed by a high-speed small-diameter wire rod finishing mill.

[Explanation of symbols]

1: Rolled material 2: First finished block mill 3: Guide pipe 4: Second finished block mill 2g, 4g: Transmission 2m, 4m: Electric motor 2c, 4c: Power converter 2k, 4k: Lead rate setting device 5: Cooling pipe 6: Pinch roll 7: Ray head 8: Product index

Claims (1)

(57) [Claims] In a high-speed fine wire finishing mill composed of two block mills arranged in series, both ends are used before the leading end of the material bites into the first finishing block mill and passes through the second finishing block mill. Change the mill speed control circuit from PI control to P
A speed control method for a wire finishing mill including two block mills, wherein the control is switched to compensate for a decrease in the mill passage characteristics of the material tip caused by a speed impact drop when the material tip bites into the second finishing mill.