JPS6059046B2 - Gaugemeter type automatic plate thickness control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a cage meter type automatic plate thickness control system that uses a rolling mill itself as a type of plate thickness measuring machine to control plate thickness.

The thickness of the final product produced by cold rolling varies widely depending on its use, and the accuracy of the thickness is rough for thick plates, but for ultra-thin steel plates with a thickness of O, 4Tfgn or less, the tolerance value is very large. Strict.

The plate thickness accuracy of this rolled material is determined by the plate thickness deviation.
There are two main causes of sheet thickness deviation: One is factors other than the cold rolling mill, such as changes in the thickness of the entrance plate and roll gap setting errors. Another problem is the variation in plate thickness caused by rolling in a rolling mill, which includes variations in tension, oil film, rolling friction, thermal expansion of the rolls, and roll eccentricity. Among these plate thickness variation factors, disturbances other than roll eccentricity have relatively slow fluctuation cycles, so it is easy to take countermeasures. This problem has almost been solved by using a monitor M°C that feeds back the plate thickness deviation signal from the thickness gauge to the rolling down device. for example,
Hydraulic rolling mills have become common in recent cold rolling mills, so the quick response of hydraulic rolling is utilized to increase the apparent rigidity of the rolling mill in a gauge meter type automatic plate thickness control system. A model equipped with variable mill constant control is adopted to control the plate thickness based on the thickness of the plate, increasing plate thickness accuracy.

However, with the gauge meter type automatic plate thickness control system,
Since the reduction blade is detected and the amount of elastic deformation of the rolling mill is calculated and correction control is performed, fluctuations in the reduction blade due to roll eccentricity are accentuated, which has the disadvantage that the effect of roll eccentricity is amplified by changes in plate thickness. ing.

In other words, even though the roll gap has become smaller due to the eccentricity of the rolls, the load increases, so the roll gap must be corrected to become even smaller.
Further, since the plate thickness fluctuation due to roll eccentricity has a relatively fast period, it cannot be followed by the monitor AGC, and almost no effect can be expected. This will be briefly explained together with the principle of gauge meter type AGC with mill constant variable control. The rolling blade is F1, the mill constant of the rolling machine is M1, and the roll gap is S. Then, the outlet plate thickness h is equal to the sum of the roll gap setting value and the amount of elongation due to elastic deformation of the rolling mill, and is expressed by equation (1). Now, if we consider a slight change from a certain target exit side plate thickness, we will get the following.

Therefore, the gauge meter type M° C. makes Δh zero by controlling the roll gap with a value proportional to ΔF/M in the second term on the right side of equation (2).

In other words, the Mill constant variable control equivalently changes the Mill constant by changing the tuning rate k in equation (3). When k=1, Me becomes infinite, and when ΔSO=0, the exit side plate thickness deviation becomes zero. However, in response to changes in the roll gap such as roll eccentricity,
The control amount of the gauge meter type AGC works in the direction of increasing the change in plate thickness, and when k=1, the change in the roll gap increases the length. This is reflected in the plate thickness on the exit side. In this way, the gauge meter type M°C is effective against variations in plate thickness on the entrance side, and if the tuning rate k is increased to near l, the welding point area can be rolled accurately, but the plate with roll eccentricity Regarding thickness accuracy
On the contrary, the higher the tuning rate is, the greater the influence becomes, so when rolling with rolls with relatively large roll eccentricity, selection of the tuning rate during the rolling process becomes a problem.

For example, as can be seen from Figure 1, which shows an example of actual measured values for rolling with a tuning rate of k=0.75, thickness vibrations, which are considered to be the effects of roll eccentricity, are observed in the exit side thickness deviation.
Due to the low tuning rate, this has not been increased much. However, if there is an abnormal area, such as a welded area, that is thicker or harder than other parts, the tuning rate will not be so high in the area passing through the welding point, and the plate thickness accuracy will be somewhat disturbed. On the other hand, the tuning rate is k=
In FIG. 2, which shows an example of the measured value of rolling at 0.00.9, the welding point is completely rolled and the thickness deviation is almost the same as other steady rolling parts. However, the variation in plate thickness due to the influence of roll eccentricity appears larger than in the case where the tuning rate k=0.75. The present invention solves the above-mentioned problem, that is, if the tuning rate is lowered to prevent the influence of roll eccentricity, the rolling of abnormal areas such as welded areas will not be sufficient, and the plate thickness accuracy in these areas will decrease. (by increasing the tuning rate and rolling the abnormal areas sufficiently)
If the thickness accuracy of this part is improved, the effect of roll eccentricity in other steady parts will be increased.We provide a thickness control method that eliminates the conflicting factors of thickness variation, and improve the thickness accuracy. The purpose is to roll at a relatively low tuning rate when rolling in the steady rolling section, but at a higher tuning rate when rolling abnormal areas where the plate thickness or hardness suddenly increases. It is characterized by doing. That is, in the steady rolling section, rolling is performed at a lower tuning rate k = 0.7 to 0.8, which is less affected by roll eccentricity,
Only abnormal locations such as welding points that require sufficient rolling are rolled at a high tuning rate k=0.9 to 0.95. As a result, as shown in the measured values in Figure 3, although the thickness accuracy near the welding point where the tuning rate was increased is approximately the same as that of other rolled parts, the overall rolling rate is low, that is, the rolls. Rolling can be performed with less influence of eccentricity. Therefore, the accuracy of the plate thickness including the welding points can be improved. FIG. 4 shows a specific example of the method of the present invention.

The gauge meter type automatic plate thickness control system (AGC) is activated by a command from the control device 13 after a certain period of time after the rolled material 2 is caught in the rolling mill 1, and at the same time. The rolling blade at this time detected by the load cell 4 is stored in the storage device 11 as a lock-on value of the gauge meter type M°C. Thereafter, the deviation amount ΔF between the detected rolling blade and the lock-on value is calculated by the addition amplifier 12, and then multiplied by the coefficient unit 14 to obtain the correction amount of the roll gap. The lowering device is operated based on this correction amount. A position detector 7 for detecting the movement of the cylinder is installed in the lowering device consisting of the cylinder 5 and the cylinder ram 6. The output signal of the position detector 7 is fed back to the cylinder 5 via the addition amplifier 15, the servo amplifier 16, and the servo valve 8, thereby configuring a position control system. In other words, it is checked whether the cylinder has operated or not in accordance with the amount of correction of the roll reduction position according to the amount of mill elongation outputted from the coefficient unit 14, and the cylinder is controlled to move. Rolling machine 1
A welding point detection unit 3 installed on the entry side of the welding point detects passage of the welding point, and this detection signal is sent to the control device 13 to adjust the value of the tuning rate k of the coefficient unit 14 for a certain period of time. Replace with value. By the way, in the case of the actual measurements shown in Figure 3, the tuning rate k=
The tuning rate k = 0.7, which was used to roll at k = 0.75, was replaced with a tuning rate k = 0.9 that allows sufficient rolling in response to a detection signal of passage of the welding point. The above-mentioned fixed time, ie, tuning rate replacement time, may be set by time, or another welding point detector may be installed on the exit side of the rolling mill 1 to return to the tuning rate before the change. Naturally, consideration is taken to smooth the change in the tuning rate so as not to affect the plate thickness at the moment of switching the tuning rate. In addition, 9 is a hydraulic pump, and 10 is an oil tank. In this way, when rolling areas other than abnormal areas such as welding points, rolling is performed at a low tuning rate that is less affected by roll eccentricity, while at the same time, the abnormal area is detected before it gets caught in the rolling roll and the tuning rate is increased to ensure sufficient rolling. Since rolling is performed, the welding point can be completely rolled, and rolling can be performed with less influence of roll eccentricity over the entire area, making it possible to further improve plate thickness accuracy.

In the above embodiment, passage of the welding point is detected using the welding point detector 3, but it may be directly instructed by the operator.

In addition, as a specific example, we have explained a rolled material with welding points, but this is not limited to cases where it is known in advance that the hardness or plate thickness will increase rapidly in some areas, or vice versa, where the hardness or plate thickness is decreased. The control method of the present invention can also be applied.

[Brief explanation of the drawing]

Figure 1 shows the tuning rate k=0 in a gauge meter type automatic plate thickness control system equipped with a mill constant variable control function.
Figure 2 is a graph showing the measured value of plate thickness accuracy when an ultra-thin plate is rolled at a tuning rate k of 0.9. The abnormal part was tuned to other steady parts with a tuning rate of k=0.9. FIG. 4 is a block diagram showing a specific example of a gauge meter type automatic sheet thickness control system equipped with a mill constant variable function. In the drawing, 1 is a rolling machine, 2 is a rolled material, 3 is a welding point detector, 4 is a load cell, 5 is a cylinder, 6 is a cylinder ram,
7 is a position detector, 8 is a servo valve, 9 is a hydraulic pump,
10 is an oil tank, 11 is a lock-on value storage device, 12,
15 is an addition amplifier, 13 is a control device, and 14 is a coefficient unit.

Claims (1)

[Claims] 1. In a gauge meter type automatic sheet thickness control system with a mill constant variable control function, rolling is performed at a relatively low tuning rate during rolling in the steady rolling section, while rolling is performed at a relatively low tuning rate when rolling at an abnormal location where the sheet thickness or hardness has suddenly increased. A gauge meter type automatic plate thickness control method characterized by rolling with a high tuning rate.