JPS6213084B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a rolling mill equipped with a gauge meter type rolling control mechanism and a plate thickness correction mechanism that is activated when a rolled member is passed through the rolling mill. Relates to a method by which the invention may be controlled.

In recent years, the requirements for plate thickness accuracy of rolled products have become stricter, and various automatic plate thickness control methods such as the gauge meter method (BISRA method) have been used to achieve almost good accuracy during normal rolling. It is now possible to roll the sheet to a thickness of . However, during low-speed rolling in which the leading and trailing ends of the rolled member pass through the rolling mill, the plate thickness control methods such as the gauge meter method described above are not sufficiently effective. This resulted in off-gauge areas where the plate thickness was considerably thicker than the target plate thickness, leading to a decrease in yield. The main reason for this is that the low rolling speed increases the coefficient of friction between the rolled member and the rolls, and the oil film on the bearings that support the back-up rolls becomes thinner, resulting in the spacing between the rolls (hereinafter referred to as this). (referred to as a roll gap) substantially increases, and when the tip of the rolled member is pushed into the rolling mill and passes through it, the tension on the side where the rolled member is wound is further applied to the rolled member. This is because the apparent deformation resistance increases because no load is applied.

Therefore, in order to improve the yield by reducing the number of off-gauge points, the roll gap during low-speed rolling is narrowed by a predetermined amount compared to the roll gap during normal rolling by operating a reduction screw or reduction cylinder ram, etc. Recently, sheet thickness correction based on a program control method that brings the thickness of both ends of a rolled member closer to the target thickness has begun to be adopted in various places.

However, when a gauge meter type thickness control is started to maintain a constant thickness in parallel with the program control for thickness correction when a rolled member is passed through a rolling mill, the tip of the rolled member is Conventionally, even if an attempt was made to widen the roll gap to a predetermined interval when transitioning from low-speed rolling to high-speed normal rolling after plate thickness correction was completed, the roll gap would not widen as instructed. In other words, a value completely opposite to the rolling force command value for the rolling rolls at the start of thickness correction is given at the start of normal rolling in an attempt to return to the rolling force before plate thickness correction, which was set in advance assuming normal rolling. However, because the amount of narrowing of the roll gap at the start of thickness correction did not match the amount of widening of the roll gap at the start of normal rolling after the completion of thickness correction, the number of off-gauge locations for the rolled material as a whole decreased, but it was still normal. The accuracy of plate thickness due to rolling was not very good. This is because the setting value (lock-on value) of the rolling force of the rolling roll according to the gauge meter type plate thickness control method is the value set during plate thickness correction during sheet passing, and normal rolling is started after plate thickness correction is completed. When the roll gap is widened when starting, the rolling force decreases, so the gauge meter type plate thickness control operates the roll screws, roll cylinder rams, etc. so that the roll gap returns to its original spacing. This is caused by the amount of expansion of the roll gap being different from its command value.

To explain the relationship between such a control process and plate thickness with reference to Fig. 1, first, at T ₁ , the tip of the workpiece to be rolled is bitten into the rolling roll of the rolling mill, and at T ₂
Start plate thickness correction during sheet threading, narrow the roll gap by a predetermined amount, and when the plate thickness becomes constant,
At T ₃ , gauge meter type plate thickness control is started to maintain this plate thickness constant. When the tip of the rolled member completely passes through the rolling rolls of the rolling mill and the threading operation is complete, the thickness correction is canceled at T ₄ , and the target thickness H ₀ and this plate shown by the two-dot chain line in the figure are Deviation from the plate thickness of the rolled member during thickness correction Δh ₀
The rolling force of the rolling rolls is weakened by a certain amount corresponding to T5, and the work is completed at _T5 .
However, as mentioned earlier, when the roll gap is widened from T ₄ to T ₅ , the thickness control using a gauge meter, which operates in response to changes in the rolling force of the rolling rolls due to changes in the roll gap, increases the rolling force. The correction operation is automatically performed, and a deviation of Δh ₀₁ remains between the target plate thickness H ₀ and the actually rolled plate thickness from T ₅ onwards.

From this point of view, the present invention provides a plate thickness correction mechanism that narrows the roll gap to a predetermined amount so that the tip of the rolled member, which is rolled at low speed, has approximately the target thickness when the rolled member passes through the rolling mill. The above-mentioned problems in rolling mills equipped with a gauge meter type plate thickness control mechanism have been solved, and the difference between the actual rolled plate thickness and the target plate thickness when passing from low-speed rolling to normal rolling has been solved. It is an object of the present invention to provide a method for controlling plate thickness that eliminates deviations and enables rolling to a highly accurate plate thickness.

The structure of the plate thickness control method of the present invention that achieves this objective is such that the rolling rolls are adjusted so that the tip of the rolled member, which is rolled at low speed, has approximately the target thickness when the rolled member is passed through the rolling mill. In a rolling mill equipped with a plate thickness correction mechanism that narrows the interval to a predetermined amount and a gauge meter type plate thickness control mechanism, the plate thickness correction mechanism corrects the plate thickness at the tip of the rolled member and then shifts to normal rolling. When performing this correction, the rolling force setting value set in the gauge meter type plate thickness control mechanism that is activated during this plate thickness correction is made to correspond to the plate thickness deviation between the plate thickness at the time of plate passing and the target plate thickness. , calculation formula ΔF ₀
=M+(1-k)Q/k・Δh ₀ (However, ΔF ₀ is the transition amount, M is Mill constant, k is the tuning rate, Q is the plasticity coefficient, and Δh ₀ is the plate thickness deviation). Either change it based on ΔF ₀ and shift to target thickness control, or change the rolling position setting value to correspond to the thickness deviation between the thickness at the time of sheet passing and the target thickness, and use the calculation formula. Calculated using ΔS ₀ = M + (1-k) Q/M・Δh ₀ (where ΔS ₀ is the return amount, M is Mill constant, k is the tuning rate, Q is the plasticity coefficient, and Δh ₀ is the plate thickness deviation). The return movement is performed based on the return amount
It is characterized by shifting to target plate thickness control.

By the way, as shown in Fig. 1 mentioned above, in the thickness correction section during sheet passing, the tip of the rolled member is rolled to be thinner than the target thickness H ₀ , so the thickness correction is discontinued and the process shifts to normal rolling. The plate thickness of the rolled member at time T ₄ is thinner than the target plate thickness H ₀ by Δh ₀ (plate thickness deviation), and at this point, the gauge meter type plate thickness control is already in operation. here,
The roll gap value that is initially set when correcting the plate thickness is S ₀ , the rolling force setting value of the rolling roll at ₃ points T (rolling force lock-on value) is F ₀ , and the rolling force of the rolling roll at ₄ points T is F ₁ , if the tuning rate in the gauge meter method plate thickness control is k and the mill constant is M, then from the gauge meter method H ₀ −Δh ₀ =S ₀ +k(F ₀ −F ₁ )/M+F ₁ /M...
(1) The following relationship is established. On the other hand, the rolling force F ₁ of the rolling roll at this point (T ₄ ) is calculated as F ₁ =MQ/M+Q{H, where Q is the plasticity coefficient of the rolled member and H _i is the thickness of the rolled member before rolling. _i + k (F ₁ - F ₀ )/M-S ₀
}...(2) They have the following relationship. Therefore, the roll gap is expanded by giving a return command value of Δh ₀ as the amount of expansion of the roll gap, but the deviation between the actual plate thickness and the target plate thickness H ₀ at the end of this operation (T ₅ ) is Δ
h ₀₁ and the rolling force of the rolling roll at this time is F ₂ , the following formula holds true.

H ₀ −Δh ₀₁ =S ₀ +Δh ₀ +k(F ₀ −F ₂ )/M+F ₂
/M……(3) F ₂ =MQ/M+Q{H _i +k(F ₂ −F ₀ )/M−S ₀
-Δh ₀ }... (4) Therefore, Δh ₀₁ is obtained by subtracting equation (1) from equation (3), and becomes Δh ₀₁ = (1-k) (F ₁ - F ₂ )/M... (5) , and F ₁ −F ₂ is obtained by subtracting equation (4) from equation (2) and becomes F ₁ −F ₂ =MQ/M+(1−k)Q・Δh ₀ ……(6), so this ( Substituting equation 6) into equation (5), we end up with Δh ₀₁ = (1-k)Q/M+(1-k)Q・Δh ₀ ...(
7) is obtained.

According to this equation (7), even if a return command value of Δh ₀ is given to the rolling roll, the roll gap will not actually widen by an amount corresponding to Δh ₀ due to the action of the gauge meter type plate thickness control, and will become Δh ₀₁ . This shows that it is not possible to return by an amount corresponding to the deviation, and this has already been stated repeatedly. Note that if normal localization control is performed without employing gauge meter type plate thickness control, the tuning rate k will be zero, resulting in extremely low plate thickness accuracy.

Therefore, in the method of the present invention, when the plate thickness at the tip of the rolled member is corrected by the plate thickness correction mechanism and then transferred to normal rolling, the gauge meter type plate thickness control mechanism that is activated during the correction of the plate thickness is The predetermined rolling force set value (rolling force lock-on value) is changed in accordance with the thickness deviation between the plate thickness at the time of sheet passing and the target plate thickness, thereby shifting to target plate thickness control. In other words, a device with a function to correct the rolling force set value was installed, and the rolling force set value of the gauge meter type plate thickness control mechanism was corrected in a fixed pattern when the plate thickness correction during sheet threading was completed. It is.

The rolling force setting value (rolling force lock-on value) of the gauge meter type plate thickness control mechanism during plate thickness correction during plate passing is F ₀ , and the plate thickness deviation (plate thickness correction amount) is Δ.
h ₀ , the rolling force setting value after completion of the plate thickness correction return operation during sheet threading, that is, the rolling force setting value after the change, is F ₀ ′, and in this case, the final rolling force setting value to be slid is F ₀ ′. On the other hand, if the rolling force at that point is F ₁ ', then the following formula holds true.

H ₀ =S ₀ +k(F ₀ ′-F ₁ ′)/M+F ₁ ′/M...
(8) F ₁ ′=MQ/M+Q{H _i −S ₀ +k(F ₁ ′−F ₀ ′
)/M}...(9) Therefore, from (8)-(1), Δh ₀ = (1-k)(F ₁ ′-F ₁ )/M+k(F ₀ ′-
F ₀ )/M (10) On the other hand, the following relationship holds between the variation in the rolling force and the change in the set rolling force from equations (2) and (9).

(F ₀ ′−F ₀ )=M+(1−k)Q/−kQ・(F ₁ ′−F ₁
)...(11) Substituting this equation into equation (10), F ₀ ′-F ₀ =M+(1-k)Q/k・Δh ₀ =ΔF ₀ ...(1
2) Using this equation (12), the calculation unit of the control device calculates the amount of change ΔF ₀ of the rolling force set value, and slides the rolling force set value at the same time as the return operation starts (T ₄ in Figure 1). The rolling force setting value is changed by a transition amount ΔF ₀ at the setting return time. When the rolling force set value is changed by ΔF ₀ , the distance between the rolling rolls becomes a distance corresponding to the target plate thickness H ₀ , and rolling is performed to make the rolled member the target plate thickness H ₀ .

In another aspect of the present invention, when the plate thickness at the tip of the rolled member is corrected by the plate thickness correction mechanism and then transferred to normal rolling, a gauge meter type plate thickness control mechanism is started while the plate thickness is being corrected. While continuing the operation, the rolling position of the rolling roll is moved by a return amount calculated in accordance with the thickness deviation between the thickness at the time of passing and the target thickness to shift to target thickness control. I made it. In other words, while the gauge meter type plate thickness control is continued, the return amount of the rolled down position is commanded, including the correction amount due to the gauge meter type plate thickness control.

In this case, if the return amount is ΔS ₀ and the reduction force after completion of return is F ₁ ′, then H ₀ =S ₀ +ΔS ₀ +k(F ₀ −F ₀ ′)/M+F ₁ ′/M
...(13) F ₁ =MQ/M+Q{H _i −S ₀ −ΔS ₀ +k(F ₀ −F ₁ ′
)/M}...(14) From (13)-(1), Δh=ΔS ₀ +(1-k)(F ₁ '-F ₁ )/M is obtained.

On the other hand, from (14)-( ₂ ), (F _{1 '} -F _{1 )} =-MQ/M+(1-k) Q・ΔS ₀ ...
Since the relationship (15) holds true, the amount of return ΔS ₀ =M+(1−k)Q/M·Δh ₀ (16) is obtained.

Using this equation (16), the return amount ΔS ₀ ' is calculated in the calculation unit of the control device, and the lowered position is changed at the same time as the return operation is started, and the lowered position is changed by the return amount ΔS ₀ ' in a predetermined return time. By doing so, the rolling position, that is, the distance between the rolling rolls becomes a distance corresponding to the target plate thickness H ₀ , and rolling is performed to make the rolled member to the target plate thickness H ₀ .

Embodiments of the present invention will be described below with reference to FIG.

After the material to be rolled 2 is caught in the rolling mill 1, plate thickness correction is started. The plate thickness correction amount is set in a digital setting device (plate thickness correction amount setting device) 3.

The rolling force after a certain period of time after the rolled material is bitten is stored in the rolling force setting value storage device 4 as the rolling force setting value. For the subsequent rolling force, an addition amplifier 5 calculates the amount of correction from the set value of the rolling force, and a coefficient unit 6 determines the amount of roll gap correction.

In the first embodiment, at the same time as the plate thickness correction during sheet passing is completed and the correction return operation is started, the control device 7 controls the plate thickness correction return amount setter 8, the mill constant setter 9, the rolled material Using the return amount (correction deviation) Δh ₀ , the mill constant value M, and the rolled material plasticity coefficient value Q set by the plasticity coefficient setting device 10, the correction amount ΔF ₀ of the rolling force setting value is calculated by equation (12). Then, the contents of the rolling force set value in the storage device 4 are changed.

In the second embodiment, while the gauge meter type plate thickness control mechanism is kept operating, the control device 7 controls the plate thickness correction return amount setter 8, the mill constant setter 9, and the rolled material plasticity at the same time as the start of the plate thickness correction return. Coefficient setter 1
Using the return amount Δh ₀ set by 0, the mill constant value M, and the rolled material plasticity coefficient value Q, from equation (16), the return amount ΔS ₀ of the rolled down position required to actually return by Δh ₀ is calculated. is calculated and added to the addition amplifier 11 as a command value.

In addition, in the drawing, 12 is the cylinder of the rolling mill 1, and 13 is the cylinder of the rolling mill 1.
14 is a cylinder drum, 14 is a hydraulic power source, 15 is a hydraulic pump, 16 is a servo valve, 17 is a reduction position detector, 18 is a servo amplifier, and 19 is a changeover switch.

Further, the present invention is not limited to the above embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

For example, although the above embodiment describes the return operation for only one stand, the same operation may be performed for each stand of a tandem rolling mill or any stand, or each stand may use a combination of return methods. Also good.

As described above, according to the plate thickness control method of the present invention, the rolling force setting value is calculated in accordance with the plate thickness deviation between the plate thickness during threading and the target plate thickness, and the gauge meter method plate thickness is The rolling force set value in the control mechanism was changed, or the amount of return of the rolling position was calculated in response to the plate thickness deviation, and the rolling position was changed accordingly to shift to normal rolling. Therefore, it has become possible to further improve plate thickness accuracy and reduce off-gauge parts.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between the control process and plate thickness accuracy in a conventional rolling mill equipped with a plate thickness correction mechanism and a gauge meter type plate thickness control mechanism during sheet passing, and Fig. FIG. 2 is a system diagram showing the general principle of an embodiment of the plate thickness control method according to the invention. In the drawing, 1 is a rolling machine, 2 is a material to be rolled, 3 is a digital setting device, 4 is a rolling force setting value storage device, 5 is an addition amplifier, 7 is a control device, 8 is a plate thickness correction return amount setting device, 9 1 is a mill constant setting device, 10 is a rolling material plasticity coefficient setting device, and 11 is an addition amplifier.

Claims (1)

[Scope of Claims] 1. A plate thickness correction mechanism that narrows the interval between rolling rolls to a predetermined amount so that the tip end of the rolled member, which is rolled at low speed, has approximately the target thickness when the rolled member is passed through a rolling mill. In a rolling mill equipped with a gauge meter type plate thickness control mechanism, when the plate thickness at the tip of the rolled member is corrected by the plate thickness correction mechanism and then transferred to normal rolling, during this plate thickness correction. The rolling force set value determined for the gauge meter type plate thickness control mechanism to be operated is made to correspond to the plate thickness deviation between the plate thickness at the time of plate passing and the target plate thickness, and ΔF ₀ =M+(1-k) Q/k・Δh ₀ However, ΔF ₀ is the amount of transition, M is Mill constant,
k is the tuning rate, Q is the plasticity coefficient, Δh ₀
is changed based on the transition amount ΔF ₀ determined by the plate thickness deviation to shift to target plate thickness control, or the rolling position set value is Corresponding to the thickness deviation, ΔS ₀ =M + (1-k)Q/M・Δh ₀ However, ΔS ₀ is the return amount, M is Mill constant, k
is the tuning rate, Q is the plasticity coefficient, and Δh ₀ is the return movement based on the return amount obtained from the plate thickness deviation,
A plate thickness control method characterized by shifting to target plate thickness control.