JPS6018496B2 - Shape control device in rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shape control device for a rolled plate material 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 legs, the
The value is approximately 00rm. In other words, there is a difference of 10 mm between the thickness at the center of the plate and the thickness at the green edge, and if the plate thickness is guaranteed to be a minimum value, there is an extra volume corresponding to the plate crown. Become. 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 characteristics. 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, such as 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 by the plate crown and shape correction ability. There is a limit to this, and a sufficient effect cannot be expected especially when the medium of the plate changes to medium.

For example, in hot rolling, the plate material to be rolled is generally rolled according to a schedule called the coffin schedule, in which it is first rolled to medium width, then wide to medium, and finally to fine. Bender has little use for 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 crown and shape of the plate can be effectively formed even if the inside of the plate changes, and high-quality plates can be provided at a high yield. The present invention further improves this and makes it possible to achieve good shape control with respect to fluctuations in the sheet and other factors by performing appropriate control in combination with a roll bender.

In the shape control device for a rolling mill of the present invention, the effective chest in contact with the work roll has one type of length shorter than the work roll body length, and the effective chest has a roll diameter of 1.0 or more. A rolling mill is provided with a reinforcing roll with a large convex crown, and the working roll is provided with a roll pending device, and an actual measured value of rolling load and an actual measured value in the plate are input,
The present invention is characterized in that it has a calculator that outputs an optimal roll pending force, and a device that controls the roll pending device so that the actual roll pending force becomes equal to the optimal roll pending force. This will be explained in detail. 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 and 3b, this roll has a diameter smaller than the roll ear for a certain length 1 as shown in the figure, and the diameter is larger at the middle part of length L, so the effective chest area that comes into contact with the work rolls 2a and 2b. Moreover, a convex crown is attached to the circumferential surface of this part. 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. More than 2, preferably 2. Gives a convex roll crown about the size of a snout. 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 a steel strip rolling mill, the effective roll body length L when rolling a plate in the range of 3 feet to 7 feet is 5.
It is most effective to provide a roll crown (for example, ΔR=1 fence) at the position of 1.5 feet (1.5 feet) from the viewpoint of the contact length during rolling, the effective roll body length, and the plate crown characteristics.

Regarding the effective body length L, in any plate, the shorter the length, the smaller the plate crown. However, if the thickness is too large, medium elongation will occur in the rolled plate material, and the contact stress between the work roll and the reinforcing roll will increase, making spalling more likely to occur. Therefore, the minimum effective roll body length L is regulated by medium elongation limits, spalling limits, and the like. In the rolling mill shown in FIG. 1, the work roll 2a is
, 2b try to fly upwards and downwards, the reinforcing rolls 3a,
3b suppresses this, and the amount of sagging is greatest at the center, but since the reinforcing rolls 3a and 3b have the largest diameter at the center, they can effectively suppress this sagging.

In addition, the amount of manipulation increases as the rolling load increases, but at this time, due to their elastic deformation, the reinforcing rolls 3a and 3b come into contact with the work rolls 2a and 2b over a wider contact area, and eventually they automatically follow the rolling load. This is a variable body length roll that increases or decreases the body length depending on the length of the roll.Since the rolling load corresponds to the inside of the plate, the above also applies when the inside of the plate changes.
As a result, this rolling mill can effectively prevent crowning and shape defects from occurring in the rolled plate material even if the rolling reduction rate, plate thickness, etc. change. Furthermore, the reinforcing roll 3a
, 3b are attached to the work rolls 2a, 2b in a predetermined range 1 at both ends thereof.
It is also important that the rolls are not in contact with each other, 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 effectively applied to the work roll, and the shape can be effectively controlled by the roll bender. Shape control using a roll bender also has a long-range response within the range where it is effective.
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. Incidentally, there are various factors that determine the amount of crown, in addition to the rolling load, such as the initial profile of the work roll, changes in it due to thermal expansion, wear, etc.

In order to appropriately deal with these factors and always obtain the desired plate crown and shape, the rolling mill shown in FIG. 1 alone is still insufficient, and appropriate control and adjustment is necessary. In view of the above, the present invention attempts to perform extremely effective and reliable shape control by using the rolling mill shown in FIG. 1 in combination with a roll bender. Next, the present invention will be explained in detail using examples. FIG. 3 shows an example of the relationship between the rolling load P (tons) and the optimum roll pending force Fo (tons) for flattening the sheet shape using the plate inside B in the rolling mill of FIG. 1 as a parameter. As shown in this graph, the optimum roll pending force can be determined by knowing the inside of the plate and the rolling load. The desired value of the shape is not necessarily zero, but it may be desired to set it to a certain appropriate value.

For example, if the material to be rolled is hard, cracks are likely to occur at the edge of the plate, so it is preferable to roll the plate to the extent that it generates ear waves.In this case, rolling is performed to make the exit side plate crown slightly larger than the input side plate crown. Become. Even in such a case, since a P-Fo characteristic curve as shown in FIG. 3 can be drawn for the desired shape, Fo can be determined from it. The present invention attempts to perform feedback control of the roll pending force using the relationship shown in FIG. 3 to control the shape of the plate, and an embodiment thereof is shown in FIG. 4. In Fig. 4, 1, 2a and 2b, and 3a and 3b are rolled plate materials as in Fig. 1;
These are a work roll and a reinforcing roll.

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 a plate detector for the plate material 1 to be rolled, 6 is a computer or arithmetic unit, 7 is a comparator, 8 is a roll pending force control device,
9 is a roll pending force detector, and 10 is a rolling load detector.

To explain the operation, ``When the rolling load P in the plate is measured by the detectors 5 and 10, the calculator 6 uses the relationship shown in Fig. 3 to calculate the optimum roll pending force Fo that brings the crown to the desired value. The comparator 7 calculates the difference Er between this pending force Fo and the actual roll pending force F measured by the detector 9, and inputs this to the control device 8. The control device 8 determines that this difference Er is zero. Generate a roll pending force in the roll pending device 4 so that
As a result, the plate shape is controlled to a desired value. As explained in detail above, according to the present invention, in a four-high rolling mill equipped with a reinforcing roll having an effective body length shorter than that of the work roll and having a convex crown, the controllability of the plate shape is improved by using a roll bender in combination, It is possible to provide a long-responsive shape correction ability that is more effective against fluctuations in the plate, which has a great effect on improving product quality and walking distance, and has the feature of a relatively simple structure. .

[Brief explanation of the drawing]

Figure 1 is a schematic front view showing the structure of the previously proposed four-high rolling mill;
2A to 2E are explanatory views showing the shapes of various roll crowns, FIG. 3 is a characteristic curve diagram, and FIG. 4 is a block diagram showing an embodiment of the present invention. In the drawing, 2a and 2b are work rolls, 3a and 3b are reinforcing rolls, 4 is a roll pending device, 6 is a calculator, 7,
8 is a control device for the roll pending device. Figure 1 Figure 2 Figure 4 Figure 3

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. further comprising: a rolling mill in which the work rolls are equipped with a roll bending device; a calculator that receives the actual measured values of the rolling load and the actual measured plate width and outputs the optimum roll bending force; and a calculator that outputs the optimum roll bending force; A shape control device for a rolling mill, comprising a device for controlling the roll bending device so as to be equal to the optimum roll bending force.