JPS61147913A - Meandering control method in thick plate rolling - Google Patents

Abstract

PURPOSE:To increase the shape quality and products yield by selecting the optimal gains for the plate thickness, plate width and estimated crown on each rolling pass and by performing the correction of the roll draft position based on this optimal gain. CONSTITUTION:The list of optimal gains is made and prepared on each pass by experienced or off-line simulation model in advance classified by the plate thickness, plate width and estimated crown in a PID gain setting part 7. The plate thickness, plate width and estimated crown information on each rolling pass are given from the host computer each rolling stock, the optimal gains list is retrieved on each time and the decided optimal gains are automatically selected. The divergence command of the right and left rolls is operated by the prescribed equation from the right and left differential load detected by a load cell 3 and the meandering of the rolling stock 2 is controlled by controlling the servo valve 6 for hydraulic automatic control. With this method, the shape quality and yield of the rolling stock 2 are increased.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention adjusts the opening degree of the left and right rolls based on the rolling load difference between the left and right rolls that occurs due to the off-center of the thick plate when rolling a thick plate. The present invention relates to a meandering control method for correcting the rolled down position of a roll.

(Prior Art) A model diagram of rolling in thick plate rolling is shown in FIG. Figure 1 (~ shows a state in which a rolled material 2 with a plate width B is rolled with a deviation of δ■ from the center of the rolling mill l to the work side (WS). In this state, the workpiece to be formed on the rolled material 2 is The center Q of the resultant force of the side rolling load PW and the drive side rolling load PD is located on the drive side (DS) from the center of the rolling mill 1.
Therefore, the distribution of rolling load per unit length in the width direction of the rolled material 2 is as shown in Fig. 1(b), where Pd >
It becomes PW.

Since pw > FD, the roll gap changes in the direction of opening at WS and closing at DS. Therefore, the thickness distribution on the outlet side of the rolled material 2 is as shown in Figure 1 e), where the thickness hw of the work side and the thickness hD of the drive side are hW >
It becomes hD. At this time, compared to WS, the rolled material 2 of DS
The advancing speed at the input side of the rolling mill 1 becomes slow, and the rolled material 2 tends to bend toward the WS at the input side, and the meandering progresses further. In addition, in Fig. 1), k indicates the spring constant on one side of the rolling mill 1, but the material plate thicknesses hW, hD on the exit side of the rolling mill 1 are
is expressed by the following equation (1).

PW hW=sW + /), , bn-sD+ PD/l
c...α) Here, SW is the roll opening degree i on the work side.
9D is the roll opening degree of the drive side. Therefore, the left and right plate thickness difference h(1f(-hW -hD) is h(If-C$1-SD) + (PW -FD
)/ni-Sdf + Pdf/k ・Song・-Song・Song…
...becomes a melodic song (g). In this way, the left and right roll opening difference is 8
By detecting the difference P(if) between df and the rolling load, it is possible to know the difference Mf in thickness of the left and right plates on the exit side.

Meandering m* means that the rolling reduction ratios of WS and 08 are made equal so that there is no speed difference between the left and right sides of the WS and the entry side of the field. For example, the cross-sectional shape of the entrance plate is rectangular, that is, WS and DB.
Assuming that the plate thicknesses are the same, in order to prevent the plate from meandering,
It may be set to haf-0.

sdr + Pdf/k -o ・------ Song---
By controlling 5(if) so that it becomes --・-(s), the difference in thickness between ws and DS can be made zero. In other words, Sat + aPdf/k −o −−−−−
--Curve--If BClf is controlled to satisfy (4), that is, by changing α (P gain of PID gain), the apparent stiffness of the rolling mill l in the width direction can be changed. . In the case of Fig. 1, Pdf > 0, so from equation (4), St −5D−Bat −−αPdf/k < 0−(
5), so SW<SD, that is, WSe opening direction, D
Meandering can be prevented by controlling S in the closing direction. In other words, if the board snakes toward WS, it is WS.
If the winding meandered towards the DB, the DB may be controlled to be closed by an amount that can correct the meandering amount.

However, in the normal arc of a thick plate, the temperature difference between the left and right sides of the rolled material,
Due to the difference in the thickness of the left and right plates on the entry side and the unbalance of the detected rolling load values on the left and right sides, the relationship between the difference in rolling load on the left and right sides and the amount of meandering is l to l.
does not correspond to Therefore, in order to prevent the left-right rolling load difference caused by the above-mentioned cause from being mistakenly caused by the meandering of the rolled material and to perform erroneous control, the differential load caused by causes other than meandering is set to Paft1 (lock-on difference). load)
The following method is generally used to control meandering. In other words, if Pat is the actual differential load detected during rolling, then the value ΔPdf, which is obtained by subtracting the differential load Pafo caused by causes other than meandering from pat, is the differential load caused by meandering, so it is expressed as the following equation: Become.

ΔPdf −Par −Pdfo・−−−−−−−−
--(6) In order to prevent the plate from meandering, use the following formula 8df + αΔPdf/k -Q-...
- (?) It is sufficient to perform 5att- control so as to satisfy.

Japanese Patent Publication No. 45-8780 describes correction of plate shape based on meandering when rolling steel strips, etc. Special Public Service 1977-100
8, the method described in Japanese Patent Publication No. 59-86866 has been proposed.

An example of conventional meandering control is shown in a block diagram in FIG. As shown in the figure, the conventional meandering fa control method is based on the differential load p generated when the work roll l of the rolling mill that rolls the rolled material 2 and the rolled material 2 are off-center (meandering).
A pair of left and right load cells 8 for measuring af-pws-PDS, a four-door seven plate 4 for taking out the load from the load cells 8 as voltage, Memorize the rolling load Pdfo (O, S seconds), and compare the lock-on differential load P(ifo and differential load P(if) with the lock-on differential load Pdfo, and calculate the difference Pd
f-P(if.

The calculation unit 10 multiplies &/k (at coefficient here, kst constant) and roughly multiplies gain αx (1) to 80PI.
The system 111 consists of a microcomputer 9 for outputting left and right roll opening commands having a D gain setting section γ, etc., and a hydraulic pressure reduction control panel 6 for operating the left and right hydraulic automatic thickening leg valves 6, etc. To explain the operation of this control method, the rolled material 8 is off-center (
The differential load Pe1t generated by the rolling material 3 is detected by the load panel 4 via the load cell 8, and the lock-on differential load Pdfo immediately after the rolled material 3 is bit is detected by the microcomputer 9 for commanding the left and right roll opening. The difference Pd
&/k (a: coefficient, k: main) by the calculation unit 1G on f-Pdf0.

, constant), and further multiplied by gain α (%) by the PID gain setting section to obtain the left and right roll opening difference command value Δ-C (Δ
S*WS−ΔS*DS) is determined. The roll opening degree difference command value ΔSo7 is %Δ with respect to the center in the reel body length direction.
The oil pressure level of the left and right oil pressure automatic thickness control servo valves 6 is dynamically controlled via the oil pressure reduction control panel 5 by distributing the opening difference by SO*.

(Problem to be solved) However, with conventional control methods, when the plate thickness is large,
When the plate thickness is small, even if the off-center amount (deviation of the top center of the plate width relative to the mill center) is the same, the amount of differential load generated is larger when the plate thickness is small, that is, ΔP machining: the plate thickness is small. Actual differential load ΔP at the off-center moment when the plate thickness is large: Actual differential load ΔP00 at the off-center moment when the plate thickness is small: Differential load Δpoo caused only by off-center factors when the plate thickness is small: Differential load ΔPkm caused only by off-center factors when the plate thickness is large: Differential load ΔPkBs generated due to the deformation resistance difference when the plate thickness is small: Due to the deformation resistance difference when the plate thickness is large Assuming the differential load that occurs, ΔP −Δpoo +ΔPkm, −・−−−−−・−
・CB)ΔP−Δpoo +ΔPkms・・・・・・
・・・・・・・・・・・・(9) s Therefore, the differential load caused only by the off-center factor when the plate thickness is small, and the difference load caused only by the off-center factor when the plate thickness is large. Even if the differential load that occurs is equal, that is, Δpoa - ΔP00°, ΔPkIn〉ΔPkm, so ΔP engineering〉
ΔP.

Conversely, when the actual differential load at the off-center moment when the plate thickness is small is equal to the actual differential load at the off-center moment when the plate thickness is large, that is, ΔP - ΔP.

When ΔP km, > ΔPkm, #ΔP00□〈ΔP00
．． Therefore, the off-center amount is smaller when the plate thickness ratio is higher.

In the conventional meandering control method, the gain is constant regardless of the size of the plate thickness, and the left and right roll opening difference command is output using equation (7). Therefore, as mentioned above, when the differential load is the same,
When the left and right roll opening difference commands are the same and the plate thickness is small, the control amount becomes too large even though the off-center amount is small, conversely promoting meandering of the plate or not being able to control it enough. That was the result. In addition, if the plate width is wide, the plate crown is small, or the plate has a negative crown, the centripetal action is small, so the differential load is locked on after the plate is engaged, and then the left and right roll opening difference is controlled by the deviation of the differential load. However, it is difficult to prevent the meandering of the board, and sideways bending of the board inevitably occurs compared to when the board is thick, narrow, and has a large crown.

(Means for Solving the Problems) The present invention aims to provide a meandering control method in thick plate rolling that can eliminate and improve the drawbacks and problems of conventional methods. The above object can be achieved by providing a meandering control method in plate rolling as described in the claims. That is, the present invention provides a meandering control method in which the opening degree of the left and right rolls is adjusted based on the rolling load difference between the left and right rolls that occurs due to the off-center of the thick plate during rolling of a thick plate, and the rolling position of the rolls is corrected. Select the optimum gain corresponding to the plate thickness, plate width, and predicted crown of the rolled material for each rolling pass; By correcting the roll rolling position based on the optimum gain, meandering and camper of the rolled material can be reduced in each rolling pass. The present invention relates to a meandering control method in thick plate rolling that suppresses the occurrence of meandering.

The meandering control method in thick plate rolling according to the present invention will be explained below. The present invention is basically the same as the meandering control of the conventional method explained in the block diagram of FIG.
df is detected by the load cell board 4 via the load cell 8,
The left and right roll opening command microcomputer 9 compares the lock-on differential load P dfo immediately after the rolled material 2 is bitten, and the calculation unit 10 calculates a/
Multiply by k (a: coefficient, k: t constant), and then PID
Multiply the gain α (%) by the gain setting section F to obtain the left and right roll opening difference command value ΔSc*(Δs”ws−ΔS*Da)
Determine. The roll opening difference command value Δs (3 is hΔs Although the oil pressure level is controlled by the dynamo main vine, it is significantly different from the conventional method in the settings of the PID gain setting section.The plate thickness is thinner,
The wider the strip width and the smaller the predicted crown, the higher the sensitivity to meandering, so in the PID gain setting section), the gain is set for each rolled material so that the gain can be set smaller for each strip thickness, strip width, and predicted crown. Alternatively, for each rolling pass, a table is prepared so that meandering can be automatically controlled using the optimum gain for each rolling size predicted experimentally or by an offline simulation model in advance. For example, the table is as shown in Table 1, where plate thickness (pass exit side plate thickness), plate width,
The gain αl) for each predicted crown is XI, Xs * X
The first performance was watched as s...... The plate thickness, plate width, and predicted crown information for each rolled material and each rolling pass are given by the host computer (Procomputer), and Table 1 is searched each time, and the determined optimal gain α is automatically selected. The left and right roll opening command Δs□ is determined from the detected differential load using the following formula, and the left and right hydraulic pressure is automatically controlled to control meandering.

*.

Δs□−(cpar−paro)x”/,)α−(10
) where (lc: t constant, a: coefficient, α-gain) Next, the present invention will be described with reference to embodiments.

Example In conventional thick plate rolling, the PID gain was set at 90%, but the plate thickness was 4.5 to 8 mm and the plate width was aoo.

~4 Q Q QllllB, plate length 80,000 N40
The gains were set as shown in Table 2 for a rolling size of ,000 m.

Table 2: Gain setting table A thick plate with the dimensions mentioned above was rolled with this gain/gay/ The amount of lateral bending (camber) of the board was significantly reduced.

However, n is the number of data. Although the method of the present invention is applied, it is of course not necessary to apply the method of the present invention to all passes, and the effectiveness can be exerted even if an appropriate pass is selected and implemented.

(Effects of the Invention) As explained above, in the meandering control method in thick plate rolling of the present invention, the optimum gain is selected according to the plate thickness, plate width, and predicted crown of the material to be rolled for each rolling pass, and the optimum gain is By correcting the rolling position of the rolls based on the above, we were able to significantly reduce the bending of the plate and obtain thick plates with a good shape, improving the product yield and having an extremely large effect. It is.

[Brief explanation of drawings]

Fig. 1 <8) is a rolling mill model diagram, Fig. 1 ｽ) is a rolling load model diagram, Fig. 1 @) is a plate thickness distribution diagram, and Fig. 2 is a conventional meandering control block diagram. l...Rolling mill work roll S2...pressure [material, 8...
・Load cell (load detector), 4...Load cell panel,
5...Hydraulic reduction control board, 6...Hydraulic automatic thickness control servo valve, 7...PID cane setting section, 8...Lock-off load storage layer memo! J-, 9*7・Left, Arita-
Microcomputer for outputting the valve opening difference command, 1G... calculation section. 41rrass person Kawasaki-Tetsu Co., Ltd. Kinsha-Daibanto Bentanshi Seitoshi Murata Patent attorney Hata IYG Ya

Claims (1)

[Claims] 1. A meandering control method that adjusts the opening degree of the left and right rolls based on the rolling load difference between the left and right rolls that occurs due to the off-center of the thick plate during rolling of a thick plate, and corrects the rolled down position of the rolls. In: Select the optimum gain corresponding to the plate thickness, plate width, and predicted crown of the rolled material for each rolling pass; By correcting the roll rolling position based on the optimum gain, the rolled material can be adjusted in each rolling pass. A method for controlling meandering in thick plate rolling, which is characterized by suppressing the occurrence of meandering and camber.