JPS6018497B2 - Rolling mill plate crown control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plate crown control device for a plate material to be rolled in a rolling mill.

When a plate is rolled using a rolling mill, a crown is formed on the rolled plate as is well known.

For example, in hot rolling of a steel plate with a thickness of 2 to 3 sides, the
The value is approximately 0.00 French m. In other words, there is a difference of 100 m between the thickness at the center of the board and the thickness at the green edge, and if the minimum thickness is guaranteed, there is an extra volume corresponding to the crown of the board. becomes. In addition, it is generally desirable for the thickness of the steel sheet to be constant for each part; for example, in the case of electrical equipment such as motors and transformers that use a large number of laminated electromagnetic steel sheets, differences in thickness may affect assembly work and electrical properties. This is especially true as it can have a negative impact on By the way, in order to control the crown to be flat at a desired value, for example, zero or in the middle direction, a roll pending method for work rolls in a four-high rolling mill has been developed and has achieved some results, but this method is limited to the ability to correct the plate crown. Therefore, sufficient effects cannot be expected, especially when the medium of the plate changes to medium.

For example, in the hot rolling of steel plates, the rolling process is generally carried out according to a schedule called a co-fin schedule. In that case, roll benders have little effect on crown control. Therefore, the present applicant first devised a four-high rolling mill in which the effective length of the support roll was shortened and a convex crown was provided on the peripheral surface of the roll, and filed an application for the same. According to this rolling mill, the plate crown can be effectively controlled even if the inside of the plate changes, and high-quality plates can be provided with a high yield. The present invention further improves this and makes it possible to achieve good crown control for fluctuations in the sheet and other factors by performing appropriate control in combination with a roll bender. In the plate crown control device for a rolling mill of the present invention, the effective body part in contact with the work roll is shorter than the work roll body length and has one type of length, and the effective body part in contact with the work roll has one type of length, and the roll diameter is 1 ．． In addition, it is equipped with a reinforcing roll with a large convex crown that is larger than the ship's side.
A rolling mill equipped with a roll pending device on the work rolls, various data necessary for plate crown control such as steel type, plate width, plate thickness, rolling reduction, tension, roll diameter, plate shape limit values, and actual measured value of entrance plate crown. is input, and a calculator outputs the appropriate exit plate crown value, the rolling load in the plate, and the optimal roll pending force, and calculates the roll pending force correction amount from the difference between the measured exit crown value and the appropriate exit plate crown value. A device for determining the roll pending force, and a device for controlling the roll pending device so that a value obtained by correcting the optimum roll pending force by a roll pending force correction amount matches an actual measured value of the roll pending force,
Next, a detailed description will be given with reference to the drawings. FIG. 1 shows the basic form of a rolling mill previously proposed by the applicant.

In this figure, 1 is a plate material to be rolled, 2a and 2b are work rolls, and 3a and 3b are reinforcing or supporting rolls. The main difference between this rolling mill and the known four-high rolling mill is that the reinforcing roll 3
a, 3b, the diameter of this roll is small for a certain length 1 from the end of the roll body as shown in the figure, and the diameter is large in the middle part of the length L, so that the effective body that contacts the work rolls 2a, 2b is small. This part has a convex crown on its circumferential surface. The reinforcing rolls of conventional four-high rolling mills are also provided with convex crowns in consideration of roll wear, but the size of the crowns is at most about 0.2 of the roll diameter.

On the other hand, the reinforcing rolls 3a and 3b have a roll diameter of at least 1. At least 2, preferably 2. Gives a convex roll crown that is about the same as the surface of an object. As illustrated in Fig. 2 a to e, there are various shapes of roll crowns, such as trapezoid a, polygonal line b, sinusoidal curve c, parabola d, and e, which is a shape in which a crown is attached to the trapezoid of a above. However, it is preferable that the effective roll body length L (e.g., the heat of about 8 feet of body length) is regulated by either the medium elongation limit or the spalling limit under the rolling conditions of the largest plate of the material to be rolled, as shown in e. In finishing rolling of intermediate steel strip rolling, a roll crown (for example, △R=1
The most effective method is to provide a contact length during rolling, a substantially effective roll body length, and plate crown characteristics.

Regarding the effective body length L, in any plate, the shorter the length, the smaller the plate crown.

However, if it is made too small, medium elongation occurs in the rolled plate material, and contact stress between the work roll and the reinforcing roll increases, making spalling more likely to occur. Therefore, the minimum effective roll body length L' is regulated by medium elongation limits, spalling limits, etc. In the rolling mill shown in Fig. 1, when the work rolls 2a and 2b try to move upward or downward due to the rolling load, the reinforcing rolls 3a and 3b suppress this, and the amount of operation is greatest at the center, but the reinforcing rolls Since the diameters of 3a and 3b are the largest at the center, this bulge can be well suppressed.

In addition, the amount of sag increases as the rolling load increases, but at this time, due to their elastic deformation, the reinforcing rolls 3a, 3b come into contact with the work rolls 2a, 2b over a wider contact area, and eventually, automatically according to the rolling load. It becomes a variable torso length roll that increases or decreases the torso length. Since the rolling load corresponds to the inside of the sheet, the above also applies when the inside of the sheet changes. As a result, with this rolling mill, it is possible to reduce and control the plate crown of the rolled plate material even if the rolling reduction rate, plate thickness, etc. change. Furthermore, the reinforcing rolls 3a and 3b are the work rolls 2a.
, 2b are not in contact with each other in the predetermined range 1 at both ends, and as a result, the roll pending force is not restrained by the support roll at the end of the work roll, so it is well applied to the work roll, and the crown control by the roll bender is effective. It is carried out in a regular manner. Crown control by roll bender is
As long as it works well, it is reasonable and quite effective. Therefore, it is a great advantage that this method is effective for various types of plates. A 6-high rolling mill has also been proposed in which an intermediate roll is added to the 4-high rolling mill, and the intermediate roll is shifted from side to side. As it becomes necessary, it is inevitable that it will become larger and more complex. By the way, the factor that determines the amount of crown is not only the rolling load but also the initial value of the work roll.

There are various changes such as fill, thermal expansion, and wear. The rolling mill shown in Figure 1 is still insufficient to deal with these factors appropriately and always obtain the desired plate crown.
Appropriate control and adjustment is necessary. In view of the above, the present invention attempts to perform extremely effective and reliable crown control by using the rolling mill shown in FIG. 1 in conjunction with a roll bender. Next, the present invention will be explained in detail using examples. Figure 3 shows the roll pending force F and plate crown Cr.
Indicates the relationship between As shown in this figure, F and Cr have a linear relationship with B in the plate and rolling load P as parameters. FIG. 4 is a graph showing the relationship between plate crown control and shape.

The horizontal axis shows the difference △displacement between the crown ratio 〇i/hi on the exit side and the crown ratio Cri-, /hi-, on the input side. Therefore, the origin △displacement = 0 indicates rolling with a constant crown ratio, and at this time The shape is good, and Δs: 0. Here, ΔS is the difference in elongation in the longitudinal direction between the central part of the plate and the ends of the plate determined from the plate shape, and is a shape parameter. If the difference △ is positive, this means that the crown ratio has increased, that is, rolling has been carried out with an increase in edge elongation, and if the difference △ is negative, this means that the crown ratio has decreased, that is, rolling has been carried out with an increase in edge elongation. This means that some rolling has been done. Naoko), Cri, Cri-, is the output side,
Each board crown control on the entry side, hi, hj-, indicates each board thickness on the exit side and the entry side. As shown in this figure, even if rolling is performed with edge elongation or medium elongation, that is, △fcr > 0 or △z foil 0, it will remain as it is. This is not the plate thickness h
It is reflected in △gos through the parameters ``and ``middle B''. That is, as shown in the figure, when the plate thickness is on the 3 side, a larger △ s occurs than when hi = 6, and even with the same plate thickness, the wider △ s in the board is than the narrower one. . The present invention utilizes this relationship to perform more effective and appropriate plate crown control in the rolling mill shown in FIG. 1, and an embodiment thereof is shown in FIG. 5. In FIG. 5, 1, 2a and 2b, and 3a and 3b are rolled plate materials, work rolls, and reinforcing rolls of the rolling mill shown in FIG.

Reference numeral 4 denotes a roll pending device, which is also provided on the other side of the work rolls 2a and 2b, although not shown.

5 is the input plate crown, and 6 is the output plate crown Cri-.
, Cri detectors, 7 and 9 are computing units, 8 and 11 are adders, 12 is a roll pending force control device, 13 is a roll pending force detector, and 14 is a switch that is closed during rolling.

Next, the operation of this device will be explained.

Various data required for plate crown control, such as steel type, plate medium, plate thickness, rolling reduction, tension, roll diameter, and plate shape limit values, are input to the calculator 7, and the actual measurement of the entrance plate crown is input from the detector 5. The values Cri-, are input, and these (especially h, B, Cr
i-, the limit value of △rs, etc.) and the relationship shown in FIG. 4 to determine the appropriate exit plate crown Crio, output this to the adder 8, and use the relationship shown in FIG. 3 to determine the optimal roll pending. Determine the initial setting value Fo of the force, output it to the adder 11, and further output it to the roll pending device 12.
The roll pending force is set to this initial value. Furthermore, the calculator 7 calculates the plate width B directly and the rolling load P.
is calculated from the well-known formula P=k・B・W・Q (k is a variable resistance, W is a contact length, and Q is a coefficient) and outputs these to the calculator 9. During the rolling operation, the adder 8 is inputted with the measured plate crown Cri on the output side from the detector 6, and the difference △Cr=Crjo
-Cri is output to the arithmetic unit 9. In the calculator 9, the difference △Cr
The roll pending force correction amount ΔF is calculated using the relationship shown in FIG.
Output to. The adder 11 outputs the optimal roll pending force Fo corrected by the correction amount ΔF to the roll pending control device 12, and the roll pending force acts on this value, but the roll pending force actual measurement value F from the detector 13 is and the value thereof, and outputs the difference ER to the roll pending force control device 12. The control device 12 causes the roll pending device 4 to generate a roll pending force so that this difference ER becomes zero, and controls the plate crown to a desired value Crio. The appropriate exit plate crown Crio differs for each rolling pass.

For example, in the final rolling pass, the exit side plate crown becomes the plate crown of the product, so it must be equal to the plate crown required for the product, and in the intermediate pass, the plate crown should be a large value because it can be corrected in the subsequent pass. This may improve the rolling efficiency. Of course, if an excessively large plate crown is attached and the product is required to have a flat plate crown, that is, a plate crown of zero, if the plate crown is suddenly corrected to this flat level, the shape will deteriorate significantly as shown in Fig. 4, and it will be a serious problem. In this case, rolling becomes impossible. Therefore, the computing unit 7 takes these circumstances into consideration and determines an appropriate plate crown Crio. As explained in detail above, according to the present invention, a rolling mill that itself has good crown control ability is used, and a roll bender is used to perform closed-loop automatic control for proper plate crown.
Extremely rational crown control can be performed quickly and accurately.

[Brief explanation of the drawing]

Figure 1 is a schematic side view showing the structure of the previously proposed rolling mill;
Figures a to e are explanatory views showing various shapes of the roll crown, Figures 3 and 4 are characteristic diagrams, and Figure 5 is a block diagram showing an embodiment of the present invention. In the drawing, 2a and 2b are work rolls, 3a. 3b is a reinforcing roll, 4 is a roll pending device, 7 is a calculator, 6 is an exit plate crown detector, 7 is an inlet plate crown, and various data are used to calculate the appropriate roll pending force Fo, the appropriate plate crown, and the rolling load. Calculator 8 is a comparator that compares the actual plate crown value on the exit side with the appropriate plate crown value and outputs the deviation. 9 is a change amount of roll pending force using △Cr, plate width B, and rolling load P during rolling. 11 is an addition comparator that adds the roll pending force change ΔF to the appropriate roll pending force Fo, compares that value with the actual measured roll pending force F, and outputs the deviation amount ER. , 12 is a roll pending force control device, 1
3 is. The rolling bending force detection device 14 is a switch that is turned on during rolling to form a loop that allows feedback control. Figure 1 Figure 2 Figure 5 Figure 3 Figure 4

Claims (1)

[Claims] 1. A reinforcing roll in which the effective body in contact with the work roll has one type of length shorter than the work roll body length, and the effective body has a large convex crown with a roll diameter of 1.0 mm or more. In addition, a rolling mill in which the work rolls are equipped with a roll bending device, and various data necessary for plate crown control such as steel type, plate width, plate thickness, rolling reduction, tension, roll diameter, plate shape limit values, etc. A calculator receives the actual measured value of the plate crown on the inlet side and outputs the appropriate plate crown value on the outlet side, plate width, rolling load, and optimal roll bending force, and calculates the value based on the difference between the actual measured value on the outlet side plate and the above-mentioned appropriate plate crown value on the outlet side. a device for determining a roll bending force correction amount; and a device for controlling the roll bending device so that a value obtained by correcting the optimum roll bending force by the roll bending force correction amount matches an actual measured value of the roll bending force. A plate crown control device for a rolling mill, comprising: