JPS6018495B2 - 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 plate with a thickness of 2 to 3 willows, this is 10
The value is about the same as Cape m. In other words, there is a difference of 10 meters between the thickness at the center of the board and the thickness at the edge.
If the minimum value is guaranteed, the corresponding volume will be redundant in the plate crown. In addition, it is generally desirable that the thickness of the steel sheet be the same for each part.For example, in the case of electric equipment such as motors and transformers that use many electromagnetic steel sheets in a thin layer, differences in thickness will cause assembly work and electrical problems. This is especially true because it has a negative impact on physical characteristics. By the way, to control the crown to make it flat as desired, for example in the zero or 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 has a limited ability to correct the plate crown and shape, especially when the center of the plate changes to medium. We cannot expect sufficient effects.

For example, in hot rolling, the plate material to be rolled is generally rolled according to a schedule called a coffin schedule, in which it is first rolled into a medium-sized, then wide-medium, and finally fine-sized. 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 controlled even if the inside of the plate changes, and high-quality plates can be provided with good quality. 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.

The shape control device in the rolling mill of the present invention has eight effective lengths that are in contact with the work rolls, each having one type of length that is shorter than the body length of the work rolls, and the effective chest part having the diameter of the roll. 1.
The rolling mill is equipped with a reinforcing roll with a large convex crown that is larger than the proboscis, and the work roll is equipped with a roll pending device, and data necessary for shape control is input, and the optimum roll pending force, sheet width, and a calculator that outputs a shape reference value; a device that calculates a change in roll bending force from the difference between an actual shape value of a rolled plate material and the shape reference value and the plate width; and the optimum roll pending force;
It is characterized by having a device that outputs a command value for the roll pending device from the amount of change in roll pending force and the actual measured value of 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 the plate material to be rolled, and 2a and 2b are the work rollers.
3a, 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, the diameter of this roll is smaller than that of the roll and the same machine for a certain length 1 as shown in the figure, and the diameter is larger in the middle part of length L, so the effective month of contact with work rolls 2a and 2b is smaller. It has both parts, and 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 a convex crown in consideration of roll wear, but the size of the crown is at most about 0.2 ribs in 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 cape. 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 (for example, a body length of approximately 8 feet) 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. Effective roll body length L when rolling a material plate in the range of 3 feet to 7 feet in finish rolling of hot rolled strip material
is 5 feet) and roll crown (e.g. △R=
1) is the most effective method from the viewpoint of the contact length during rolling, that is, the actual effective roll body length, and the plate crown characteristics.

As for the effective trunk length L, the shorter the length of any plate, the smaller the plate crown.

However, if it is made too small, medium elongation will occur in the rolled plate material, and 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, when the work rolls 2a, 2b try to move upward or downward due to the rolling load, the reinforcing rolls 3a, 3b suppress this, and the amount of sag is greatest at the center, but the reinforcing rolls Since the diameters of 3a and 3b are maximum at the center, this sagging can be well suppressed.

In addition, the amount of bales 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 they automatically move 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, this rolling mill can effectively prevent the occurrence of crowns and shape defects in the rolled plate material even if the rolling reduction rate, plate thickness, etc. change. Furthermore, the reinforcing roll 3a,
It is also important that the roll 3b does not contact the work rolls 2a, 2b in the predetermined ranges 1 at both ends thereof, and as a result, the roll pending force is not restrained by the support roll at the ends of the work rolls, so that it is effectively applied to the work rolls. Shape control by the rubber bender is effectively performed. Shape control using a roll bender is fast-responsive within a range where it is effective, and is quite effective. Therefore, it is a great advantage that this method is effective for various types of plates. Additionally, a 4-high rolling mill has been invented in which an intermediate roll is added to form a 6-high rolling mill in which 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 of the work roll, the profile, and its changes due to thermal expansion and wear.

In order to appropriately deal with these factors and always obtain the desired plate crown and plate 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.

If you know the inside of the plate and the rolling load as shown in this graph,
The optimal roll pending force can be determined. Next, when rolling a plate whose shape changes by changing the amount of roll pending, for example, a plate with a large entry side plate crown, and at this time, by applying a roll bender to reduce the exit side plate crown to 0, it is possible to roll the plate from the edge of the plate to the middle of the plate. The plate stretches greatly at the edges, causing mid-elongation, and if a plate with a large negative crown is rolled in the same way to reduce the crown to 0, the elongation at the edges is large, resulting in edge elongation, and the shape changes. Getting worse.

The amount of change △F (men) in this roll pending force is determined by the amount of change in shape, that is, the difference △S between the elongation at the center of the board and the elongation at the edge, as shown in Figure 4. It has a linear relationship as a parameter. By using the relationships shown in FIGS. 3 and 4, it is possible to control the plate shape to a desired value. FIG. 5 shows an example thereof. In Figure 5, 1,
2a and 2b and 3a and 3b indicate a rolled plate material, a work roll, and a reinforcing roll as in FIG. 1.

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

5 is a calculator or arithmetic unit, 6 is an adder, 7 is a roll pending force control device, 8 is a shape detector, 9 is an adder, 1
0 is a calculator, 11 is a switch that closes during rolling and opens at other times, and 12 is a roll pending force detector.

The shape detector 8 includes, for example, a vibrator and a vibration detector, detects the elongation difference from the tension distribution in the rolling direction of the plate 1, and outputs a shape signal S. The calculator 5 receives various data ○ required for shape control such as steel type, plate medium, plate thickness, reduction ratio, tension, roll protrusion, etc., and calculates the rolling load P using a well-known formula, for example, the following formula. P=k●B・W・Q) where k' is the deformation resistance, B is the inside of the plate, W is the contact length, and Q is the coefficient.

The calculator 5 further determines the optimal roll pending force FO from this rolling load P using the relationship shown in FIG. 3, and outputs this to the adder 6. The calculator 5 also determines a shape reference value SO from the input data, outputs this to the adder 9, and further outputs the input board size B to the calculator 10. The adder 9 calculates the difference ΔS between the detected shape signal S and this reference value SO, and outputs it to the arithmetic unit 10. The arithmetic unit 10 calculates the roll pending force variation ΔF from the input difference ΔS using the relationship shown in FIG. 4, and outputs this to the adder 6. The adder 6 corrects the optimum roll pending force FO inputted from the calculator 5 with the amount of change ΔF inputted from the calculator 10 through the switch 11, and uses this and the actual roll pending force fed back from the detector 12. The difference ER compared with F
is output to the control device 7 as a command value, and the roll pending force is adjusted by the roll pending device 4 to calculate the difference ER.
Make it zero. The shape reference value SO is selected to be 0, for example, when the rolled plate is desired to be flat, that is, without edge elongation or middle elongation.

Now, if there is a shape defect in the rolled plate material and S has a certain value, △S = S - SO, and △F is determined from the relationship shown in Figure 4, but this △F is This is the amount of change in roll pending force that makes the difference in elongation zero. Since FO output from the calculator 5 is the optimum roll pending force for the flat shape at the time of the rolling load P, the value F + ΔF corrected by △F is the value F + △F when the plate material having the shape defect S is P provides the roll bending force necessary for flat rolling, and if feedback control is performed using this as a reference value, desired shape control can be performed. The shape reference value SO is not necessarily zero. For example, if the plate material to be rolled is hard, cracks are likely to occur at the edges of the plate, so it is better to roll the plate to a degree that produces ear waves. In this case, SO is selected to a predetermined value that indicates the degree of ear wave generation. As explained in detail above, according to the present invention, a rolling mill that has excellent shape control ability in itself by adapting to variations in the plate is used, and further closed-loop control is performed via a roll bender to a desired shape reference value. Therefore, it is possible to exhibit large and medium shape correction ability for various steel types, rolling conditions, and plate conditions, and has a great effect on improving product quality and yield.

[Brief explanation of drawings]

Figure 1 is a schematic front view showing the structure of the previously proposed four-high rolling mill;
FIGS. 2a to 2e are explanatory diagrams showing the shapes of various roll crowns, FIGS. 3 and 4 are characteristic curve diagrams, and FIG. 5 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 Hishitaka, 6 is a calculator, 6 is an adder, 7 is a roll pending command value output device, 8 is a shape detector, 9, 10 is a computing unit, 11 is a switch, and 12 is a roll pending force detector. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

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 data necessary for shape control and outputs optimum roll bending force, strip width, and shape reference values; A device for calculating a change in roll bending force from the difference between an actual measurement value of the shape of a plate and the shape reference value and the width of the plate; A shape control device for a rolling mill, comprising: a device for outputting a command value for the roll bending device based on the value of the shape control device.