JPS6120372B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic sheet thickness control method and apparatus for a rolling mill that rolls thin metal sheets, such as strips, bands, sheets, foils, etc., particularly cold rolling.

Figure 1 shows the gauge meter type plate thickness control system (gauge meter AGC) in a conventional rolling mill.
is a roll position detector, 2 is a rolling load detector, 3 is a plate thickness standard setting device, 4 is a rolled material, 5 is a thickness gauge, 6 is a monitor circuit, 10 is a plate thickness control device, and 11 is a roll gap adjustment device. be. Figure 2 is a gauge meter
This diagram illustrates the principle of AGC.

Now, S ₀ is the roll gap (mm) when there is no material, that is, when the rolling load is "zero", F is the rolling load during rolling (TON), M is the elastic property of the rolling mill (TON/mm), h ₁
It is well known that if is the plate thickness (mm) at the exit side of the rolling mill, it is given by Hook's law of elasticity as follows: h ₁ = S ₀ + F/M (1). This formula is called the gauge meter formula.

Since M is a constant specific to the rolling mill, the plate thickness h ₁ can be calculated indirectly from equation (1) using the roll gap S ₀ and the rolling load F, so the roll gap can be controlled to make this a predetermined value. This allows the plate thickness to be controlled at a constant level. This is the so-called gauge meter AGC (hereinafter simply referred to as AGC).
That is what is said.

Furthermore, in this AGC, in order to suppress plate thickness fluctuations due to changes in roll diameter due to roll thermal expansion, changes in oil film thickness on roll bearings, etc., the material plate thickness at the exit side of the rolling mill is directly measured with an X-ray thickness meter, and the standard is determined. A monitor circuit is provided that corrects the AGC device according to the deviation value (actually, its integral value).

FIG. 2 shows the relationship between plate thickness and rolling load, where the horizontal axis is the plate thickness and the vertical axis is the rolling load. If the roll gap of the rolling mill when there is no rolled material is _S0 , the elastic property of the rolling mill is M, the plastic property of the rolled material is _m1 , and the thickness of the inlet side of the rolled material is _h0 , then the thickness of the outlet side is the characteristic M. and m ₁ intersection point A
h ₁ corresponds to .

Here, the inlet plate thickness is h ₂ and the plastic properties of the material are m ₂
, the roll gap becomes S ₁ and the thickness at the exit side becomes the intersection point B of the characteristics M and m ₂ , returning the thickness at the exit side to the predetermined value h ₁ again, but on the other hand, the rolling load also changes to △F.
only changes. As a result, the load on the rolling rolls changes and the bending of the rolls changes, resulting in a change in the shape of the rolled material and a disadvantage that the shape of the plate deteriorates. In order to correct this, it is necessary to control the shape by, for example, installing a separate roll bending device and changing the amount of bending of the roll.

When applying such a gauge meter AGC to a rolling mill that performs a new rolling method (abnormal rolling), the present invention aims to maintain the thickness correction amount at a predetermined allowable speed even if the fluctuation range of the plastic properties of the rolled material is large. If the speed ratio is within the ratio range, adjust the speed ratio of the top and bottom rolls, and if the speed ratio of the top and bottom rolls is outside the allowable speed ratio range, adjust the roll gap to keep the plate thickness constant and do not perform shape control. An object of the present invention is to provide an automatic plate thickness control method and device that can obtain a product with a constant thickness and a good shape.

The present invention will be explained below with reference to an embodiment shown in FIG. This figure shows a hydraulic rolling mill as an example, and the roll gap between rolls R ₁ and R ₂ during no load is detected by a roll position detector 1, while the rolling load is detected by a rolling load detector 2 such as a load cell. Detect with. The actual thickness of the rolled material 4 is detected by a thickness meter 5, and the deviation value from the reference value is integrated by a monitor circuit 6.
This integral output is input to the plate thickness control device 7. The output of the roll position detector 1, the output of the rolling load detector 2, the monitor circuit 6, and the reference value signal _h1 from the plate thickness reference setting device 3 are input to the plate thickness control device 7. The outputs V ₁ and V ₂ of the plate thickness control device 7 are the speed control device 8,
9, and speed control devices 8 and 9 control the speeds of electric motors M ₁ and M ₂ for driving rolls R ₁ and R ₂ , respectively. Further, the output V ₃ of the plate thickness control device 7 is applied to a roll gap adjustment device 11 to adjust the gap between the rolls R ₁ and R ₂ . Note that the thickness gauge 5 and the monitor circuit 6 do not need to be provided in principle, but are provided in order to further improve the plate thickness control accuracy as described later.

Roll gap S ₀ when no load is detected by roll position detector 1
The rolling load F is detected by the rolling load detector 2, and the plate thickness h during rolling is calculated using equation (1).
On the other hand, compare the target plate thickness h ₁ from the plate thickness setter 3 that gives the target plate thickness with the plate thickness h, and the deviation △h
For example, a proportional-integral control signal determined by the control signal is inputted to the speed control devices 8 and 9 of the upper and lower rolls through the plate thickness control device 7, and the speeds of the upper and lower rolls are changed so that h= _h1 .

It is known that the plastic property m of a rolled material changes depending on the speed ratio of a pair of rolling rolls, and an example thereof is shown in FIG. The horizontal axis is the speed ratio v _T /v _B , and v
_T and v _B are the speeds (peripheral speeds) of the upper roll R ₁ and lower roll R ₂ in FIG. 3, respectively. The length and width are the rolling load F
It is. It can be seen that when the speed ratio v _T /v _B is changed by Δ(v _T /v _B ), the rolling load F changes by ΔF, and moreover, as the speed ratio increases, the rolling load decreases.

First, a case will be described in which the necessary correction of the plate thickness at the exit side of the rolling mill can be made sufficiently within the range of the predetermined allowable speed ratio of the upper and lower rolls shown in FIG. In Fig. 5, if the roll gap of the rolling mill under no load is S ₀ , the elastic properties of the rolling mill are M, the thickness of the rolled material at the entrance side is h ₀ , and its plastic properties are m ₁ , then the thickness at the exit side is Assume that the plate thickness corresponds to the intersection point A of the characteristic M and m ₁ , and that this is maintained at h ₁ by AGC.

Next, if the entrance plate thickness changes to h ₂ and the plastic properties of the rolled material become m ₃ , then the exit plate thickness changes to the property M and m ₃
to h ₃ , which corresponds to the intersection B, and the rolling load is from F to
Each of them tries to become F ₁ . This plate thickness h ₃ is calculated using the gauge meter formula h ₃ =S ₀ +F ₁ /M, and the deviation from the set value h ₁ of the plate thickness setting device 3 △h ₁ (=
h ₃ − h ₁ ), the plate thickness control device 7 changes the speed reference of the speed control devices 8 and 9 of the electric motors M ₁ and M _{2 and}
The circumferential speed ratio v _T /v _B of R ₁ and R ₂ is decreased. For this reason, the plastic properties of the rolled material change to m ₄ in Figure 5, and the exit plate thickness h ₁ corresponds to the intersection A between the properties M and m ₄ again.
Therefore, the deviation △h ₁ is controlled to be zero.

Therefore, the rolling load returns to F again and there is no change in the rolling load F, so that the rolled material does not suffer from defects in shape due to changes in roll bending or the like.

Next, a case will be described in which the amount of correction required for the exit side plate thickness becomes even larger and it becomes impossible to correct it only by changing the speed ratio within the range of the predetermined allowable speed ratio of the upper and lower rolls. As shown in Figure 5, the entrance plate thickness changes from h ₀ to h ₂ , and furthermore, the plastic properties of the rolled material change beyond the limit of m ₃ , which can be controlled only by changing the speed ratio of the upper and lower rolls, and change to m ₅ . Let's say it's summer. In this case, the plate thickness on _the exit side is about to be h ₄ corresponding to point C, but the output signals V ₁ and V ₂ of the plate thickness control device 7 are _the allowable limit (the fourth Point “1” in the figure) is limited to the same output limit value. Therefore, the plasticity characteristic curve is a characteristic that passes through point D in section AB.
Changes to _m6 . Therefore, the deviation in the exit side plate thickness will remain by △h ₂ corresponding to point D. However, when the output signals V ₁ and V ₂ of the plate thickness control device 7 exceed the limit values, the output signal V ₃ is subsequently output and the roll gap adjustment device 11 operates, so that the roll gap between the upper and lower rolls is adjusted. Adjust to S ₂ . This roll gap S ₂ is parallel to the characteristic M passing through the S ₀ point and the characteristic M ₁ passing through the S ₂ point,
Control is performed by the roll gap adjustment device 11 so that the intersection point E of the characteristic m ₆ becomes the set plate thickness h ₁ . Therefore, the rolling pressure is _F2 equivalent to point E, so F2 equivalent to point A is
Although it deviates somewhat from the original value, the exit plate thickness is maintained at the set value _h1 and the deviation is zero. Contrary to the above, the plastic properties of the rolled material
If it changes to m ₇ , the upper and lower roll speed ratio v _T /v _B
Since the operation is the same except that the output limit value is limited to the output limit value corresponding to point a in FIG. 4, the explanation will be omitted.

In this way, the entrance plate thickness changes, the plastic properties of the rolled material,
Even if the amount of correction of the exit side plate thickness becomes large due to other external factors, the exit side plate thickness is kept constant and at the same time there is little change in the rolling load. No shape defects will occur.

The above operation has been explained for the basic case where the thickness gauge 5 and the monitor circuit 6 are not provided. When these are further provided as shown in Fig. 3, the actual plate thickness at the exit side of the rolling mill is detected by the thickness gauge 5, the deviation from the reference value is integrated by the monitor circuit 6, and this integrated output is Since the correction operation is performed by inputting the information to the plate thickness control device, the control accuracy of the plate thickness is further improved.

For this reason, if the required correction amount of the exit side plate thickness is within the predetermined allowable speed ratio range of the upper and lower rolls, the exit side plate thickness and rolling pressure are kept constant, and the required correction amount is within the allowable speed ratio range of the upper and lower rolls. Even when the rolling pressure is exceeded, the exit plate thickness remains constant, and the rolling pressure changes slightly but remains almost constant. Therefore, defects in the shape of the rolled material due to variations in roll bending, etc. do not occur.

In the above description, the speed reference of the speed control devices 8 and 9 is changed, but the speed reference of either one may be changed.

Furthermore, in the above explanation, the upper and lower rolls R ₁ and R ₂ are driven by separate electric motors, but in order to drive the upper and lower rolls by a common electric motor and change the relative speed between the upper and lower rolls, for example, a continuously variable transmission is used. When using the plate thickness control device 7 shown in FIG. 3, a speed control device (not shown) of the electric motor for driving the continuously variable transmission may be controlled by the output of the plate thickness control device 7 shown in FIG.

As explained above, according to the present invention, even if the range of variation in the plastic properties of the rolled material is large, the speed ratio of the upper and lower rolls is adjusted within the allowable speed ratio of the upper and lower rolls, and the plate thickness and rolling load are kept constant. If the speed ratio falls outside the allowable speed ratio range, the roll gap is adjusted, so the rolling load changes somewhat but the plate thickness remains constant. Therefore, (a) compared to conventional AGC, the rolling load does not change within a certain range as described above for the same change in the plastic properties of the rolled material, and the rolling load does not change even for large changes in the plastic properties. Since there are few changes, products with good shape can be obtained.

(b) Therefore, a roll bending device and a shape control device for controlling the shape of the plate are not required, making it economical.

(c) By using both the speed ratio adjustment of the upper and lower rolls and the roll gap adjustment, it is possible to continue controlling the plate thickness while keeping the rolling load close to constant even when the plate thickness cannot be controlled solely by the roll speed ratio. Compared to conventional AGC, this method has many advantages, such as allowing for more flexible sheet thickness control.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a conventional plate thickness control device, Fig. 2 is a characteristic diagram of a conventional plate thickness control device,
FIG. 3 is a block diagram showing the configuration of the automatic plate thickness control device of the present invention, FIG. 4 is a characteristic diagram of rolling pressure with respect to roll speed ratio, and FIG. 5 is a characteristic diagram of the plate thickness control device of the present invention. R ₁ , R ₂ ... Roll, M ₁ , M ₂ ... Electric motor,
1...Roll position detector, 2...Rolling load detector, 3...Plate thickness reference setting device, 4...Rolled material, 5...
... Thickness gauge, 6... Monitor circuit, 7, 10... Board thickness control device, 8, 9... Speed control device, 11... Roll gap adjustment device.

Claims (1)

[Scope of Claims] 1. In a rolling mill in which opposing rolling rolls sandwiching a rolled material are operated at different speeds, the roll gap and rolling load of the rolling mill are detected, and the roll gap and rolling load are compared with the rolling mill. Calculate the exit plate thickness of the rolling mill from the mill constant of When the speed ratio between the rolling rolls is controlled, and when the speed ratio exceeds the predetermined speed ratio range, the roll gap of the rolling mill is further controlled while maintaining the speed ratio at the predetermined speed ratio. An automatic plate thickness control method characterized by: 2. In a rolling mill in which opposing rolling rolls sandwiching a rolled material are operated at different speeds, the roll gap and rolling load of the rolling mill are detected, and the roll gap and rolling load of the rolling mill are detected, and the Calculate the outlet side plate thickness of the rolling mill, and calculate the difference between the rolling rolls by the sum of the deviation of the calculated outlet side plate thickness from the set plate thickness and the integral value of the deviation of the plate thickness performed by the rolling mill from the set plate thickness. An automatic plate thickness control method characterized by controlling a speed ratio, and when this speed ratio exceeds a predetermined speed ratio range, maintaining the speed ratio at the predetermined speed ratio and further controlling the roll gap of the rolling mill. . 3. A roll position detector for detecting the roll gap of the rolling mill, a rolling load detector for detecting the rolling load of the rolling mill, a plate thickness reference setting device for setting the plate thickness of the rolled material, and the roll position detector. The output, the output of the rolling load detector, and the output of the plate thickness standard setter are inputted to calculate the exit side plate thickness deviation of the rolled material, and a speed correction signal is output based on this deviation, and this speed correction signal exceeds a predetermined value. a plate thickness control device that outputs a roll gap correction signal in the case of a roll gap; a speed control device that inputs the speed correction signal of the plate thickness control device and controls the speed ratio between opposing rolls of the rolling mill;
An automatic plate thickness control device comprising: a roll gap adjustment device that inputs the roll gap correction signal and controls the roll gap of the rolling mill. 4. A roll position detector that detects the roll gap of the rolling mill, a rolling load detector that detects the rolling load of the rolling mill, a plate thickness standard setting device that sets the plate thickness of the rolled material, and a A thickness gauge that detects the thickness of the side-rolled material and outputs a thickness deviation signal, and a monitor circuit that inputs the thickness gauge output and outputs an integral output.
The output of this monitor circuit, the output of the roll position detector, the output of the rolling load detector, and the output of the plate thickness reference setter are inputted, and the exit side plate thickness deviation of the rolled material is calculated, and this deviation and the integrated output of the monitor circuit are input. a plate thickness control device that outputs a speed correction signal based on the sum of and a roll gap adjustment device that inputs the roll gap correction signal and controls the roll gap of the rolling mill. Control device.