JPH0237245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling plate thickness and width of a hot strip mill that simultaneously controls tension between stands, and an apparatus for implementing the method.

Conventionally, a looper has been used in a hot strip mill to keep the tension of the rolled material constant between the stands. Also, even in hot strip mills that do not use such a looper, the tension between the stands is controlled at a constant level. Incidentally, hot strip mills use automatic plate thickness control (hereinafter referred to as AGC) to control the plate thickness. Figures 1 and 2 show the changes in plate thickness and width when AGC is applied to the skid area and when it is not applied.
When AGC is applied to the skid section, the change in board width increases as shown in Figure 2. The reason for this is that when the skid area is controlled by AGC, deformation resistance occurs in the length direction due to differences in temperature and hardness, and due to this change, the amount of reduction in the skid area is greater than in the non-skid area. Cross flow (spreading in the width direction of the plate) occurs, and the width of the plate becomes wider in the skidded area compared to the non-skidded area. Therefore, even if the plate thickness is within the allowable deviation from the target value, the plate width becomes uneven in the length direction, which is unfavorable in terms of yield.

The present invention automatically controls the plate thickness by determining the roll gap change amount from the plate thickness deviation signal, and simultaneously controls the tension between the stands, thereby eliminating plate width fluctuations caused by changes in the rolling reduction, especially in the skid area. The purpose is to improve product yield.

If the plate width before rolling is B ₁ and the plate width after rolling is B ₂ , then B ₂ −B ₁ /B ₁ = C・r ^3/2・f (B ₁ , H, R) ...(1) However, C is a constant, r is the rolling reduction ratio, and f is a function of the sheet width B ₁ before rolling, the sheet thickness H before rolling, and the roll diameter R.

The relational expression holds true.

The size of the plate thickness at the skid mark part is h + Δh (h
is the target value and Δh is the deviation), then at the skid part
The change ΔB in plate width when AGC is activated is calculated from equation (1) as follows: ΔB=∂/∂Δh [C・B ₁・r ^3/2・f(B ₁ , H, R)]・(−Δh ) = ∂/∂r[C・B ₁・r ^3/2・f(B ₁ , H, R)]・∂r/∂h・(−Δh) =3/2・C・B ₁・r ^{3 /2}・f(B ₁ , H, R)・Δh/H =3/2・B ₂ −B ₁ /r・Δh/H =3/2・Δh/H−h・(B ₂ −B ₁ ) ...(2) becomes.

Therefore, if the thickness of the plate at the skid mark portion is known, the spread of the plate width ΔB can be determined from equation (2).

Equations (1) and (2) are for the case where the tension between the stands is 0, but when there is tension, Equations (1) and (2) are corrected to obtain B ₂ - B ₁ /B ₁ = C・r ^{3 /2}・f(B ₁ , H, R) −A・t _f ...(3) ΔB=3/2・Δh/H−h・(B ₂ −B ₁ )−A・Δt _f
・ B ₁ ...(4) However, A is a constant and t _f is a tension coefficient.

You can use

Therefore, calculate the plate thickness deviation Δh at the skid part and operate the AGC, and at the same time control the tension between the stands so that the left side of equation (4) becomes 0, that is, the plate width spread ΔB becomes 0. By doing so, changes in board width at the skid portion can be prevented.

As means for controlling the tension between the stands, there are means such as controlling the pushing force of a looper, or, if there is no looper, adjusting the tension by controlling the speed of a roll drive motor.

An embodiment of the present invention will be described with reference to FIG.
1 and 2 are respective stands, 3 is a rolled material that moves in the X direction, 4 to 7 are work rolls, 8 to 11 are back up rolls, 12 and 13 are load cells, 14 and 1
55 is a lowering device, 16 is a looper roll, 17,1
8 is a drive device, and 21 is a roll gap detector, both of which are known.

Now, in this embodiment, P/K obtained by dividing the rolling load P detected by the load cell 12 by the mill constant K by the divider 19, the target plate thickness h output from the plate thickness target setter 20, and the roll gap detector 21 The detected roll gap amount S is inputted to the arithmetic unit 22 to obtain the plate thickness deviation Δh. This Δh is input to the roll gap change calculation device to obtain the roll gap change ΔS, and the signal ΔS controls the rolling down placement (for example, rolling screw, hydraulic cylinder), and the signal ΔS is input to the work roll drive motor control circuit 24. Then, the current change amount ΔI ₁ corresponding to the rolling speed change amount corresponding to the change amount of the rolling torque acting on the rolling rolls is calculated to control the rotational speed of the work roll 6 and perform plate thickness control. On the other hand,
The roll gap change amount ΔS is input to the looper roll drive control circuit 25, the current change amount ΔI ₂ is calculated, and the upward force of the looper roll is controlled via the looper drive device 18.

In addition, the speed change amount ΔV of the work roll 6 that is changed when changing the roll gap of ΔS above is calculated by setting the speed of the rolled material to Vf, the advance rate to fi, and the work roll speed to V.
Then, Vf=(1+fi)×V ……(5), and in order to compensate for the roll gap change of ΔS, the rolling material speed Vf should be set as ΔVf=(−Ai/H)×ΔS ……(6) Ai: Since it is necessary to correct only the coefficient determined from the rolling theory, from both equations, ΔV=(-Ai/(1+fi)H)×ΔS...(7).

As a result, in the skid portion, as shown in FIG. 4, not only variations in the plate thickness but also variations in the plate width are reduced.

In this embodiment, the looper driving device is actuated by the current signal ΔI ₂ , but the roll gap change amount ΔS may be converted into a hydraulic signal and a hydraulic cylinder is driven to control the looper pushing force.

When the looper is not used, the stands 1 and 2 are controlled by the speed control by the roll drive electric motor 17.
It is also possible to adjust the tension.

In addition, in the above embodiment, the gauge meter type AGC
Although described above, the plate thickness deviation Δh can also be determined from the target value and the actual measurement value.

Note that although this embodiment has described feedback AGC, the same applies to feedback AGC.

As described above, the present invention calculates the amount of change in roll gap from the plate thickness deviation signal and automatically controls the plate thickness to keep the plate thickness constant while simultaneously controlling the tension between the stands. This has the effect of preventing fluctuations and improving product yield.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 are characteristic diagrams of plate thickness and plate width at the skid portion, Fig. 3 is an explanatory diagram of an embodiment of the present invention, and Fig. 4 is a characteristic diagram of the plate thickness and plate width at the skid section according to an embodiment of the present invention. It is a characteristic diagram of board thickness and board width. 12, 13... Load cell, 14, 15... Lowering device, 16... Looper roll, 17... Work roll drive motor, 18... Looper roll drive device, 23... Roll gap amount calculation device, 24...
...Work roll drive motor control circuit, 25...
Looper roll drive control circuit.

Claims (1)

[Claims] 1. Calculate the plate thickness deviation based on the rolling load, target plate thickness setting value, and roll gap amount, calculate the roll gap change amount from the calculated value, and adjust the rolling device and work roll based on the roll gap change amount. A hot feature characterized by automatically controlling the plate thickness by controlling the speed of the driving electric motor, and at the same time controlling the looper roll based on the amount of change in the roll gap to automatically control the tension between the stands so that the spread of the plate width becomes zero. Strip mill plate thickness control method. 2. A rolling load detector, a plate thickness target setting device, a roll gap detector, a device that calculates a plate thickness deviation based on these output signals, a roll gap change amount calculation device that calculates a roll gap change amount according to the plate thickness deviation signal, It has an automatic plate thickness control device and an inter-stand tension control device, and the automatic plate thickness control device includes a rolling down device that changes the amount of rolling down based on the amount of change in the roll gap, and a speed of the electric motor for driving the work roll based on the amount of change in the roll gap. The inter-stand tension control device has a looper roll drive control circuit that controls a looper drive device so that the spread of the sheet width becomes zero based on the amount of change in the roll gap. Lip mill plate thickness control device.