JPH08276206A - Rolling mill and rolling method - Google Patents

Abstract

PURPOSE: To attain rolling mill and rolling method with the shape of the crown of a work roll so that preferable crown and shape of a rolling stock to be rolled can be attained in a multiple rolling mill with four stages or over, shifting upper and lower work rolls. CONSTITUTION: This must be a rolling mill equipped with at least backup rolls 4 and 5 and work rolls 2 and 3, whose backup rolls 4 and 5 are equipped with crowns symmetrical to the left and the right, having maximum diameters in the centers of roll barrel lengths, and whose work rolls 2 and 3 are equipped with the following crowns. (a) A maximum roll diameter is positioned in a position deviated from the center of a roll barrel length so that the crowns of upper and lower rolls are in the same shape and become in point symmetry each other to the center of the rolling mill. (b) A smoothly continuous curve is composed by the crown of the roll, and a roll diameter is monotonously decreased toward the left and the right ends of the roll from the position of the maximum roll diameter. (c) And, the curve is equipped with at least one inflection point or over on either one side of the left or the right or on both sides of them in distances from the position of the maximum roll diameter to the ends of the left and the right of the roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a work roll and a backup roll capable of accurately controlling the crown and shape of a plate which is a material to be rolled over a wide range from a narrow material to a wide material. The present invention relates to a multi-high rolling machine having four or more stages and a rolling method.

[0002]

2. Description of the Related Art In rolling a steel sheet or the like, as a method for controlling the plate thickness distribution (plate crown) and shape in the width direction of the steel sheet with high accuracy, a method of applying crowns of various shapes or a work roll is used. A method of moving the work rolls in the axial direction, a method of crossing the work rolls with each other, a method of adding roll bending, and the like are widely practiced.

Among these, as a method of controlling the plate thickness and shape by moving the work roll in the axial direction, Japanese Patent Laid-Open No. 57-9 is used.
No. 1807 uses a so-called CVC type work roll in which upper and lower work rolls or intermediate rolls are respectively provided with bottle crown roll crowns having the same shape so as to be point-symmetric with respect to the center of the rolling mill. A method for controlling the plate crown and shape of the rolled material has been proposed.
According to this method, by combining with the roll bending mechanism, the ability to control the plate crown and the shape is enhanced even with a small roll movement amount.

As a rolling method using a CVC type roll,
In addition to the method of providing a point symmetric crown only to the work roll, JP-A-62-28217 and JP-A-6-15
As disclosed in Japanese Laid-Open Patent Publication No. 309, there is a method of performing control by a compound crown that imparts a point-symmetric crown to the intermediate roll that moves in the axial direction.

However, in each of these methods, since the roll crown of the entire roll cylinder length is given by one kind of function (combination of cubic equation, cubic equation and quadratic equation, etc.), the unit roll length is It is difficult to increase the amount of change in roll diameter per contact. Therefore, it is difficult to widen the control range by increasing the difference between the plate width center roll gap and the plate end roll gap, that is, the plate crown equivalent amount. Therefore, there is a limit in reducing the plate crown and improving the shape accuracy.

On the other hand, in JP-A-56-131002 and JP-A-3-230802, when the roll crowns of the upper and lower work rolls are applied so as to be point-symmetric with respect to the center of the rolling mill, the rolls are rolled. A method is disclosed in which the entire body length is convex. According to this method, there is no local increase in surface pressure near the roll end,
There is a possibility that roll damage is small and the plate crown and shape can be controlled with high precision.

However, since it is impossible to increase the plate crown equivalent amount only by making the entire roll cylinder length convex, there is a limit to the reduction of the plate crown and the improvement of the shape as compared with the case of the CVC type roll. It is the same.

By the way, in the thick plate rolling, various plate materials from narrow width material to wide width material are manufactured by one rolling mill. Among them, in the case of narrow material, the axial movement amount of the roll can be greatly changed, so when the work roll or the intermediate roll provided with the point symmetrical roll crown is relatively moved in the axial direction, the maximum roll diameter By moving the point near the center of the strip width, it is possible to reduce the strip crown even when the rolling reduction is increased to improve the rolling efficiency.

However, in the case of a wide material in which the roll cannot be moved in the axial direction, since the maximum diameter portion of the roll is located in the vicinity of the plate width quota portion, a shape defect such as a quarter wave may occur. Under such circumstances, there is a strong demand for a technology capable of controlling the plate crown and the shape in a wide range from a narrow material to a wide material.

[0010]

DISCLOSURE OF THE INVENTION The present invention is capable of accurately determining the plate crown and shape of a material to be rolled in a wide range from a narrow material to a wide material, even if a rolling load is increased to improve rolling efficiency. It is an object of the present invention to provide a rolling mill and a rolling method for hot or cold rolling which can be controlled and which does not cause roll damage due to local increase in surface pressure.

[0011]

Means for Solving the Problems As a result of intensive studies by the inventors, the inventors have found that the above problems can be solved by optimizing the crown shapes of the backup roll and the work roll.

(1) The invention of claim 1 comprises at least a backup roll and a work roll, and the work rolls are moved relative to each other in the axial direction to control the crown and shape of the material to be rolled. In the rolling mill, the backup roll has a left-right symmetrical crown having a maximum diameter at the center of the roll cylinder length, and the work roll has the following crown. (A) The upper and lower rolls have the same shape and have a maximum position of the roll diameter at a position deviated from the center of the roll cylinder length so as to be point-symmetric with respect to the center of the rolling mill;
The crown of the roll constitutes a smoothly continuous curve, the roll diameter monotonically decreases from the maximum position of the roll diameter toward the left and right roll ends, and (c) and the curve is from the maximum position of the roll diameter. At least one inflection point is provided on one or both of the left and right sides up to the left and right roll ends.

(2) The invention of claim 2 is the rolling mill described in claim 1, wherein the curve forming the crown of the work roll has the following characteristics. (A) A sine function having the same or different amplitudes and different wavelengths from the maximum position of the roll diameter toward both ends, and (b) the curve at the maximum position of the roll diameter. , The maximum point of one sine function and the maximum point of the other sine function are connected.

(3) The invention of claim 3 is the rolling machine according to claim 1 or 2, wherein the rolling machine is provided with a work roll bending mechanism.

(4) The invention of claim 4 uses the rolling mill according to any one of claims 1 to 3, wherein the work roll of the rolling mill is a maximum point of the roll diameter of the work roll. The rolling method is characterized in that the rolling is performed by relatively moving so that is located near the width center of the material to be rolled.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the upper and lower work rolls are moved relative to each other in the axial direction, but these work rolls have roll crowns of the same shape and symmetrical with respect to the center of the rolling mill. Is given.

The crown shape of this work roll has a maximum roll diameter point at a position deviated from the center of the roll body length, and further, the roll diameter monotonically decreases to the roll end, and from the maximum roll diameter point to the left and right. Alternatively, it is a curve having one or more inflection points between at least one roll end.

When the crown is constructed with such a curve, it is possible to increase the change in the gap between the upper and lower work rolls in the roll axial direction in the vicinity of the maximum roll diameter.
Therefore, by relatively moving the upper and lower work rolls so that the maximum point of the roll diameter is located near the center of the rolling mill according to the strip width, even if the rolling reduction is increased and the rolling load is increased, the roll shaft bends. Since the plate crown caused by the flatness and the flatness can be reduced, shape defects such as generation of ear waves are improved.

A curve having one or more changes between the left and right or at least one of the ends of the work roll is preferable because the sine function is easy to implement. At the maximum position of the roll diameter, it is connected at the maximum point of one sine function and the maximum point of the adjacent sine function.From the maximum position of the roll diameter toward both ends, the amplitude is equal and the wavelength When the crown is constructed by using two or more different sine functions, the gradient around the maximum point can be increased.

Therefore, since the change in the interval between the upper and lower rolls in the axial direction can be increased, the plate crown can be further reduced. The above is the shape of the work roll.

Next, the shape and operation of the backup roll will be described. The backup roll that does not move in the axial direction during the rolling operation has the maximum diameter at the center of the body length, and is given a symmetrical crown. With this configuration, even if the work roll is bent by the rolling load, the gap between the upper and lower work rolls near the center of the rolling mill can be kept small at all times.

Further, the effect of keeping the interval between the upper and lower work rolls near the center of the rolling mill small is enhanced even if the upper and lower work rolls are relatively moved by the symmetrical crown of the backup rolls. Therefore, the effect of sufficiently reducing the plate crown can be obtained with a small amount of crown as compared with the case where the crown is provided only to the work roll.

This means that the effect of controlling the plate crown is maintained even if the shape of the roll crown of the work roll changes due to heat crown or wear. By the way, in the case of a material having a large plate width, the work roll can hardly be relatively moved. For this reason, when the upper and lower work rolls are provided with roll crowns that are point-symmetric with respect to each other, the maximum point of the roll diameter comes to be located in the vicinity of the left and right quarter plate width of the material to be rolled.

Therefore, since the roll interval in the vicinity of the center of the plate width becomes relatively large, sufficient reduction cannot be achieved, and ear waves and quarter waves tend to be generated. However, by providing the backup roll with a roll crown whose center is the maximum diameter of the roll cylinder and has a maximum diameter, the work roll can be moved by the action of rolling load even in the case of a wide material in which the work roll cannot be relatively moved. The backup roll is bent, and the difference between the relative roll intervals between the center of the plate width and the plate end can be increased, and the effect of reducing the plate crown is not reduced.

Further, in the rolling mill having the work roll and the backup roll as described above, when a work roll bending mechanism such as an increase type or a decrease type is added, the adjustment range of the work roll gap increases. Therefore, the above plate crown control capability is further increased.

Further, by adjusting the size of the roll crown and the offset amount from the roll center at the maximum position of the roll diameter, and controlling the relative movement amount of the roll in the axial direction, the upper and lower roll gaps with respect to the roll width direction are set. Because it can be changed significantly, a specific width range (for example,
It is also possible to increase the plate crown reduction effect in the plate width range where the production amount is the largest.

By the way, when the work rolls are relatively moved in the axial direction in order to reduce the strip crown and control the shape, a schedule of roll movement amount that maximizes the effect is adopted, so that the material to be rolled and the rolling material are constantly operated. There will be a part in contact with. For this reason, the wear of the roll is usually not uniform in the cylinder length direction.

In the method of rolling using the rolling mill according to the present invention, the crown-shaped work roll is placed so that the maximum point of the roll diameter is located near the width center of the material to be rolled.
Rolling can be performed by relative movement, and the initial diameter of the roll near the center of the width of the rolled material where wear greatly progresses can be made large, so the allowable wear amount up to roll reshuffling increases and the reshuffling cycle can be extended. It will be possible.

[0029]

【Example】

(Embodiment 1) The shapes of upper and lower work rolls and backup rolls, which are an embodiment of the present invention, are shown in FIG. In Figure 1,
2 is an upper work roll, 3 is a lower work roll, 4 is an upper backup roll, and 5 is a lower backup roll. As shown in FIG. 2, the work roll crown has a distance from the center of the roll body length (L) to the maximum point of the roll diameter as δ,
It is given by the functions of the following equations (1) and (2).

In the case of 1.0 ≦ x ≦ (L / 2 + δ) x ′ = πx / (L / 2 + δ) −π / 2 f ₁ (x ′) = (a / 2) · (sinx ′ + 1) −− ----- (1)

2. When (L / 2 + δ) <x ≦ L, x ′ = π {x− (L / 2 + δ)} / (L / 2−δ) −π / 2 f ₂ (x ′) = (a / 2) · ( 1-sinx ') -------- (2) where a is a coefficient representing the size of the crown.

3. Further, the crown of the backup roll is shown in FIG. 3, and can be expressed by the following formula (3). When 0 ≦ x ≦ L, x ′ = πx / L f ₁ (x ′) = f ₂ (x ′) = b · sinx ′ −−−−−− (3) where b is the size of the crown. It is a coefficient to represent.

Using a quadruple reversing type rolling mill equipped with a work roll having a roll crown and a backup roll constituted by such curves, the plate thickness is 20 mm and the plate width is 1600 to 44.
A 00 mm steel plate was hot rolled.

The crown of the sheet after rolling according to the method of the present invention and the conventional method is shown in FIGS. Figure 4 shows the load of the roll bender
The case is 300 tons, and the case of FIG. 5 is 500 tons. Similar steel sheets were hot rolled.

The maximum amount of movement of the work roll for each plate width was 1000 mm for both the upper and lower crawls, and the work roll was moved outward from the end of the plate width at a position of 150 mm. Rolling is done with work roll body length (L) 47
00mm, diameter 1200mm, backup roll body length (L) 4500mm, roll diameter 2150mm 4
The rolling mill was used.

In the conventional method 1, the work roll is provided with a point-symmetrical convex crown represented by the following equations (4) and (5), and the backup roll is not provided with a crown. In Comparative Example 2, the work roll is provided with the point symmetric crown represented by the above formulas (1) and (2), which is a part of the present invention, and the backup roll is not provided with the crown. In the above embodiment, a = b = 0.1 mm,
δ = 900 mm.

In the case of 1.0 ≦ x ≦ (L / 2 + δ) x ′ = πx / 2 (L / 2 + δ) f ₃ (x ′) = a · sinx ′ ---------- (4)

2. When (L / 2 + δ) <x ≦ L x ′ = π {x− (L / 2 + δ)} / 2 (L / 2−δ) + π / 2 f ₄ (x ′) = a · sinx ′ −−− --- (5) where a is a coefficient representing the size of the crown.

FIG. 4 shows a case where the bender load is 300 tons.
In the case of the present invention, the plate crown is reduced more than in the cases of the conventional method 1 and the comparative method 2, particularly in the range of the medium width material to the wide width material. Further, even in the case of the narrow width material, a plate crown similar to that of Comparative Example 2 was obtained, and a substantially constant plate crown was obtained regardless of the plate width.

Next, FIG. 5 showing a bender load of 500 tons.
To compare. In Comparative Example 2, the plate crown is reduced in the range from the narrow width material to the medium width material as compared with the conventional method 1, but the wide width material has a smaller effect of reducing the plate crown. On the other hand, in the method of the present invention, the conventional method 1 is used in a wide range from narrow width materials to wide width materials.
Also, the plate crown is greatly reduced as compared with Comparative Method 1.

That is, even in the case of a plate crown by the axial movement of the work roll or a wide material whose shape is difficult to control, the same effect as that of the narrow material is obtained. Further, when an incremental type or decrease type roll bender is applied, an almost constant plate crown is obtained regardless of the plate width, so that optimum plate crown and shape control are facilitated.

(Embodiment 2) Table 1 shows the results of comparing the shapes after rolling by the method of the present invention and the conventional method in the case where a bender is not used for a wide material in which the axial movement of the work roll cannot be increased. In the conventional method 3, the work roll is provided with the point-symmetrical crowns represented by the formulas (4) and (5), and the backup roll is provided with the point-symmetrical crown represented by the formula (3). Is given.

Comparative Example 2 is the same as the example performed in Example 1, but is a part of the present invention of the work roll (1),
This is a case where the point-symmetrical crown represented by the formula (2) is provided and the backup roll is not provided with the crown.

In the conventional method 3, in addition to the point-symmetrical convex crown of the work roll, the back-up roll is also provided with a bilaterally symmetrical crown. Ear waves are generated only when the plate width is immovable, but ear waves and quarter waves are more likely to occur immediately before roll replacement, which causes large wear.

On the other hand, according to the method of the present invention, a good plate shape which was almost constant during the roll rearrangement period was obtained. This is because, in the method of the present invention, a large plate crown reducing effect is obtained even with a small initial roll crown, so that even if the roll shape is slightly deformed due to abrasion, the influence on the plate shape after rolling is unlikely to change. .

[0046]

[Table 1]

As shown in FIG. 6, by rolling a work roll having a special point-symmetrical crown according to the present invention and a backup roll having a bilaterally symmetrical crown with the center of the roll cylinder length being the maximum diameter, rolling can be performed. When the work rolls are moved relative to each other in the axial direction according to the width of the material, the difference in the distance between the upper and lower work rolls between the center of the plate width and the plate end is compared with the case where only the work rolls are crowned. It is possible to increase it. As a result, even with a small initial crown, it is possible to reduce the plate crown caused by the bending and flattening of the upper and lower rolls due to the rolling load.

Further, as shown in FIG. 7, when a work roll having a special point symmetric crown according to the present invention and a backup roll provided with a symmetric crown whose center of roll length is the maximum diameter are combined, In the case of a wide material in which the amount of axial movement of the roll cannot be increased, the work roll and the backup roll are bent due to the action of the rolling load, and the relative distance between the upper and lower rolls near the center of the plate width can be kept small.

[0049]

As described above, according to the present invention, the plate crown can be reduced in a wide range from the narrow width material to the wide width material. For this reason, the reduction rate is increased in almost all strip widths, and even when the rolling load is increased, shape defects such as selvages are reduced, and it is possible to reduce the number of rolling passes up to a predetermined product sheet thickness. Efficiency is improved.

Further, by combining the work roll having the special point-symmetrical crown and the backup roll having the bilaterally symmetrical crown of the present invention, a sufficient reduction effect of the plate crown can be obtained even if the work roll has a small crown. To be Therefore, immediately after changing the rolls, when a thermal crown occurs, and even when the roll is worn, it is possible to minimize the fluctuation of the roll crown shape,
Almost constant effect can be obtained until the rolls are rearranged.

Therefore, the local load between the work roll and the backup roll, which are in contact with each other, is also reduced, and the roll damage is reduced. Furthermore, if the rolling mill according to the present invention is provided with a work roll bending mechanism such as an increment type or a decrease type, the plate crown can be further reduced. Further, by doing so, even if the reduction rate is increased, it is possible to reduce shape defects such as generation of ear waves.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a rolling mill including upper and lower work rolls and a backup roll according to the present invention.

FIG. 2 is an explanatory diagram of a function form that gives a work roll crown of the rolling mill according to the present invention.

FIG. 3 is an explanatory diagram of a functional form that gives the crown of the backup roll of the present invention.

FIG. 4 is a diagram showing a relationship between a plate width and a plate crown when a bender load is 300 tons.

FIG. 5 is a diagram showing a relationship between a plate width and a plate crown when a bender load is 500 tons.

FIG. 6 is an explanatory diagram of a positional relationship between a roll and a plate material when the work roll of the present invention is moved in the axial direction.

FIG. 7 is an explanatory diagram of a positional relationship between a roll and a plate material when the work roll of the present invention is not moved in the axial direction.

[Explanation of symbols]

 1 rolled material 2 upper work roll of rolling mill according to the present invention 3 lower work roll of rolling mill according to the present invention 4 upper backup roll of rolling mill according to the present invention 5 lower backup roll of rolling mill according to the present invention

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // B21B 37/00 BBH B21B 37/00 BBH 37/38 8315-4E 116B 8315-4E 117B (72) Inventor Toshitaka Tanaka 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Tube Co., Ltd. (72) Inventor Kazuya Fukuoka 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Tube Co., Ltd.

Claims (4)

[Claims] 1. A multi-high rolling mill having four or more stages, comprising at least a backup roll and a work roll, wherein the work rolls are moved relative to each other in the axial direction to control the crown and shape of the material to be rolled. A rolling mill having a bilaterally symmetrical crown having a maximum diameter at the center of a roll cylinder length, and the work roll having the following crown. (A) The upper and lower rolls have the same shape and have a maximum position of the roll diameter at a position deviated from the center of the roll cylinder length so as to be point-symmetric with respect to the center of the rolling mill;
The crown of the roll constitutes a smoothly continuous curve, the roll diameter monotonically decreases from the maximum position of the roll diameter toward the left and right roll ends, and (c) and the curve is from the maximum position of the roll diameter. At least one inflection point is provided on one or both of the left and right sides up to the left and right roll ends. 2. The rolling mill according to claim 1, wherein the curve forming the crown of the work roll has the following characteristics. (A) A sine function having the same or different amplitudes and different wavelengths from the maximum position of the roll diameter toward both ends, and (b) the curve at the maximum position of the roll diameter. , The maximum point of one sine function and the maximum point of the other sine function are connected. 3. The rolling mill according to claim 1, wherein the rolling mill includes a work roll bending mechanism. 4. The rolling mill according to any one of claims 1 to 3, wherein a work roll of the rolling mill is provided such that the maximum point of the roll diameter of the work roll is near the width center of the material to be rolled. A rolling method characterized by rolling by moving relative to each other so as to be located at.