JP3185628B2 - Rolling mill and rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot or cold work roll provided with a work roll capable of controlling the crown and shape of a plate as a material to be rolled with high accuracy in hot or cold rolling of a steel plate or the like. The present invention relates to a cold rolling mill and a rolling method.
Hereinafter, the work roll will be mainly described, but the principle of the present invention can also be applied to an intermediate roll. That is,
In a four-high rolling mill, the principle of the present invention can be applied to the work roll, but in a six-high rolling mill, the principle can be applied to the work roll and the intermediate roll.

[0002]

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

[0003] Among them, a method of controlling a plate thickness and a shape by moving a work roll in an axial direction is disclosed in Japanese Patent Application Laid-Open No.
As disclosed in JP-A-91807, a so-called CVC type work roll in which a bottle-shaped roll crown is provided to each of upper and lower work rolls or an intermediate roll so as to be point-symmetric with respect to the center of the rolling mill. There has been proposed a method of controlling a sheet crown and a shape of a material to be rolled by using the method.

In this method, by combining with a roll bending mechanism, the ability to control the sheet crown and shape with a small amount of roll movement is enhanced. JP-A-63-
Japanese Patent Application Publication No. 20106, Japanese Patent Application Laid-Open No. Hei 5-177218, and the like, disclose a roll crown function form having a high shape control ability.

In the CVC type work roll,
The roll crown of the entire roll body length is given by one type of function (a cubic expression, a combination of a cubic expression and a quadratic expression, a sine function, etc.).

[0006] For this reason, if an attempt is made to increase the amount of change in roll diameter per unit roll width in the roll width direction, that is, the rate of change in roll diameter, the roll diameter near the end of the roll may be extremely increased. Increased contact pressure can cause local roll damage.

Therefore, it is difficult to increase the change of the upper and lower roll gaps in the roll width direction, and there is a limit to the reduction of the sheet crown and the improvement of the shape accuracy. Here, the plate crown is the difference between the center thickness and the end thickness of the plate width.

In Japanese Patent Application Laid-Open No. 3-230802, when the roll crowns of the upper and lower work rolls are provided so as to be point-symmetric with respect to the center of the rolling mill, the roll crowns project outward with respect to the entire roll body length. A method for forming a shape is disclosed. According to this method, since there is no local increase in the surface pressure near the roll end, roll damage is small, and the crown and shape of the plate can be controlled with high accuracy.

However, it is not possible to increase the rate of change of the roll diameter by merely making the entire roll body length convex outward, so that there is a limit to the reduction of the sheet crown and the improvement of the shape. It is the same as the work roll.

[0010]

SUMMARY OF THE INVENTION According to the present invention, even if the work roll is relatively moved in the axial direction, the roll is not damaged by a local increase in the surface pressure. An object of the present invention is to provide a rolling mill and a rolling method for hot or cold rolling capable of controlling accuracy.

[0011]

As a result of extensive studies by the present inventors to solve the above problems, the upper and lower 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 a rolling mill, a crown shape of a work roll having a high sheet crown control ability was conceived.

(1) An invention according to claim 1 is a rolling mill for controlling the crown and shape of a material to be rolled by moving the upper and lower work rolls relative to each other in the axial direction, wherein the work roll has the following crown. A rolling mill characterized in that: (A) the crown of the upper and lower rolls has the maximum position of the roll diameter at a position deviated from the center of the roll body length so that the crowns of the upper and lower rolls have the same shape and are symmetrical with respect to the center of the rolling mill,
(B) the crown of the roll forms a smoothly continuous curve, and the roll diameter monotonically decreases from the maximum position of the roll diameter toward the left and right roll ends; and (c) the curve has the maximum roll diameter. Has at least one or more inflection points on one or both of the left and right sides from the position of.

(2) The rolling mill according to claim 1, wherein the curve constituting the crown of the work roll has the following characteristics. (A) From the maximum position of the roll diameter toward both ends, the roll is composed of one or more sine functions having the same or different amplitudes and different wavelengths. At the position of the maximum diameter, the local maximum point of one sine function is connected to the local maximum point of the other sine function.

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

(4) A fourth aspect of the present invention is a work roll for a rolling mill having the following shape. (A) a roll having a maximum diameter of the roll at a position away from the center of the roll body length, and (b) a curve forming a crown of the roll, wherein a curve forming the crown of the roll faces the right and left roll ends from the maximum position of the roll diameter. The diameter monotonically decreases, and (c) the curve has at least one or more inflection points on one or both of the left and right sides from the maximum roll diameter position to the left and right roll ends.

(5) The invention of claim 5 is the work roll for a rolling mill according to claim 4, wherein the curve constituting the crown of the work roll has the following characteristics. (A) At the maximum position of the roll diameter, the curve is connected at a maximum point of one sine function and a maximum point of an adjacent sine function, and (b) both ends from the maximum position of the roll diameter. , Each is composed of one or more sine functions having equal or different amplitudes and different wavelengths.

(6) According to a sixth aspect of the present invention, there is provided the rolling mill according to any one of the first to third aspects, wherein the work roll of the rolling mill has a maximum diameter of the work roll. This rolling method is characterized in that rolling is performed by relative movement so as to be located near the center of the width of the material to be rolled.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, upper and lower work rolls are moved relative to each other in the axial direction. These work rolls are provided with roll crowns having the same shape and mutually symmetrical with respect to the center of a rolling mill. Is given. As described above, in the following, a work roll includes an intermediate roll in a six-high rolling mill in addition to a work roll.

The shape of the roll crown is such that the roll diameter has a maximum point at a position deviated from the center of the roll body length, and furthermore, the roll diameter decreases monotonously to the roll end, and the roll diameter decreases from the maximum roll diameter point to the roll end At one or more inflection points (where the axial distance of the work roll is x and the crown is f (x), f ″
(Α) = 0, and a function having x = α such that the sign of f ″ (x) changes before and after x = α).

With such a crown shape, it is possible to increase the gradient of the curve near the maximum diameter of the roll. Therefore, when the roll is relatively moved in the axial direction, the upper and lower rolls at the center of the plate width of the material to be rolled are obtained. The difference between the interval (hc) and the interval (he) between the upper and lower rolls at the plate edge (Δh = hc−he,
However, Δh is an absolute value). Therefore, even if the roll is bent or flattened due to the rolling load, the difference (plate crown) between the plate width center and the plate end of the material to be rolled can be reduced.

For example, as shown in FIG. 1 to be described later, if the crown of the roll near the maximum diameter of the roll is increased and the slope of the curve is reduced at the end of the roll, the ends of the plate are closer than the center of the plate. Also increased roll spacing,
The crown of the plate is reduced and the roll wear at the center of the roll is reduced.

As the curve having the inflection point, a sine function is particularly desirable. The sine function can be expressed by the following equation. f (x) = a · sinx Here, when −π / 2 ≦ x ≦ π / 2, there is an inflection point at x = 0.

When such a sine function is connected to form the crown of the work roll, the gradient around the maximum point can be increased, and the change in the interval between the upper and lower rolls in the axial direction can be increased. Note that f (x) = a · sin
ⁿ x ⁽ⁿ is 1 or more of the real number) may be. Here, a is the amplitude.

However, at the maximum position of the roll diameter, the curve connects 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, each roll is constituted by one or more sine functions having equal or different amplitudes and different wavelengths. In this case, the crown may be determined so that the sine function takes a minimum point at one end or both ends of the roll.

When a work roll bending mechanism such as an increment type or a decrease type is added to a rolling mill provided with the above work rolls, the adjustment range of the work roll gap is increased. The sheet crown control ability is further increased.

Further, by adjusting the amount of offset of the maximum size of the roll crown and the roll diameter from the center of the roll, and controlling the amount of relative movement in the axial direction of the roll, the upper and lower roll gaps with respect to the roll width direction are obtained. Can be greatly changed, so that the effect of reducing the crown of the sheet in a specific sheet width range (for example, the sheet width range in which the production is the largest) can be increased.

When the work roll is relatively moved in the axial direction to reduce the crown of the sheet and control the shape, a roll movement schedule that maximizes the effect is adopted. Will be present. For this reason, the wear of the roll is usually not uniform in the body length direction.

When the work roll of the present invention is used and the work roll is relatively moved and rolled so that the maximum point of the roll diameter is located near the center of the width of the material to be rolled, the material of the material to be rolled which wears greatly increases. Since the initial diameter of the roll near the center of the width can be increased, the permissible wear before the roll change can be increased,
The recombination cycle can be extended.

[0029]

(Embodiment 1) FIG. 1 shows the shapes of upper and lower work rolls according to one embodiment of the present invention. The curve of the roll crown has a sine function of 1 on both the left and right of the maximum point of the roll diameter.
As shown in FIG. 2, the distance from the center of the roll body length (L) to the maximum point of the roll diameter is represented by δ, and is given by the functions of the following equations (1) and (2).

When 1.0 ≦ x ≦ (L / 2 + δ) x ′ = πx / (L / 2 + δ) −π / 2 f ₁ (x ′) = (a / 2) · (sinx ′ + 1) −−−− (1)

2. If (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.

A steel plate having a thickness of 20 mm and a width of 1600 to 4400 mm was hot-rolled using a quadruple reversing rolling mill provided with a work roll having a roll crown constituted by such curves.

On the other hand, the conventional work roll crown is point-symmetric as shown in FIG. 5, but has a convex shape outward and has no inflection point. As shown in FIG. 6, the function of the following equations (3) and (4) was used as the roll crown curve.

When 1.0 ≦ x ≦ (L / 2 + δ) x ′ = πx / {2 (L / 2 + δ)} f ₃ (x ′) = a · sinx ′ (3)

2. When (L / 2 + δ) <x ≦ L x ′ = π {x− (L / 2 + δ)} / {2 (L / 2−δ)} + π / 2 f ₄ (x ′) = a · sinx′− −−−−−− (4)

The magnitude of the load of the work roll bender (increase type) applied in the above-described quadruple reverse rolling mill is as follows.
The example of FIG. 3 is 200 tons, and the example of FIG. 4 is 600 tons.
The maximum amount of work roll movement for each plate width is 1000 mm for both the upper and lower work rolls, and the work roll is moved so that the work roll end is positioned 150 mm outward from the plate end.

Both the rolling mill of the present invention and the conventional rolling mill are point-symmetric work roll crowns, and the coefficients defining their shapes are a = 0.1 mm and δ = 900 mm. Rolls were rolled by a quadruple reversing rolling mill having a work work roll body length L = 4700 mm and a work work roll diameter of 1210 mm.

FIGS. 3 and 4 show a comparison of the strip crown after rolling. In the case of the roll crown of the present invention, the plate crown is significantly reduced over almost the entire sheet width range as compared with the conventional roll crown. Board width 2600-32
Within the range of 00 mm, the effect of reducing the sheet crown is particularly large.
In this range, since the production amount is large, the overall shape defect rate is improved, and the re-correction rate is greatly reduced.

(Embodiment 2) Next, using the half wavelength of the sine function for the longer distance from the maximum point of the roll diameter to the roll end, and using the quarter wavelength of the sine function for the shorter distance. It is an example in the case where a crown is provided. In this case, only the side using １ ／ wavelength of the sine function is a curve having an inflection point, has a shape as shown in FIG. 7, and can be expressed by the functions of the following equations (1) and (4).

When 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)} / {2 (L / 2−δ)} + π / 2 f ₄ (x ′) = a · sinx′− −−−−−− (4)

Other experimental conditions are the same as in the first embodiment. FIG. 8 shows a plate crown reducing effect when the above work roll crown is applied.
The plate crown when using such a work roll is:
Compared with Example 1 using two サ イ ン wavelengths of the sine function, the amount of reduction of the plate crown is small, but the plate crown is reduced at all plate widths compared to the conventional method, and the shape defect rate is also improved. Was done.

(Embodiment 3) Next, an embodiment in which a roll crown is provided so as to have three inflection points from the maximum point of the roll diameter to the right and left roll ends, respectively, will be described. The roll shape at this time is shown in FIG. As shown in FIG.
One sine function １ ／ wavelength. Other experimental conditions are the same as those of the first embodiment.

Table 1 shows a comparison between the sheet crown and the shape when the conventional method shown in FIG. 5 and the roll crown of the present invention are applied. In any of the sheet widths of 3000 and 4000 mm, when the roll crown of the present invention was applied, the sheet crown was smaller and the shape was better. In particular,
This is effective for preventing shape defects in the case of a plate width in which the axial movement amount of the roll cannot be increased.

[0044]

[Table 1]

[0045]

When the upper and lower work rolls are moved relative to each other in the axial direction according to the width of the material to be rolled using a rolling mill provided with the work roll crown according to the present invention, the center of the sheet width and the end of the sheet width are obtained. Since the difference between the positions of the upper and lower work rolls can be increased, the plate crown can be reduced. In addition, this makes it possible to reduce shape defects such as generation of ear waves even when the rolling reduction is increased, so that the number of rolling passes to a predetermined plate thickness can be reduced, and the production efficiency can be greatly improved.

Unlike the CVC type work roll, when the roll is relatively moved in the axial direction, no local load is applied near the roll end, so that the roll is less damaged and the economic effect is large. In this case, if the rolling mill is provided with a work roll bending mechanism of the increment type or the decrease type, the sheet crown can be further reduced. In addition, even if the rolling reduction is increased, shape defects such as generation of ear waves can be reduced. As described above, the above principle can be applied to a case where a crown is provided to an intermediate roll other than the work roll. Using the rolling mill of the present invention, the work roll is rolled by relative movement so that the roll diameter maximum point is located near the center of the width of the material to be rolled. It is possible to extend the recombination cycle

[Brief description of the drawings]

FIG. 1 is an explanatory view of upper and lower work rolls of a rolling mill according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a function form for giving a work roll crown of a rolling mill according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a sheet width and a sheet crown when a rolling mill of the present invention is used and a bender load of 200 tons is applied.

FIG. 4 is an explanatory view showing a relationship between a sheet width and a sheet crown when a rolling mill of the present invention is used and a bender load of 600 tons is applied.

FIG. 5 is an explanatory view of upper and lower work rolls of a conventional rolling mill.

FIG. 6 is an explanatory diagram of a function form that gives a work roll crown of a conventional rolling mill.

FIG. 7 is an explanatory view of a function form for giving a work roll crown of a rolling mill according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a relationship between a sheet width and a sheet crown when a bender load is 200 tons using a rolling mill according to another embodiment of the present invention.

FIG. 9 is an explanatory diagram of upper and lower work rolls of a rolling mill according to another embodiment of the present invention.

FIG. 10 is an explanatory diagram of a function form for giving a work roll crown of a rolling mill according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Material to be rolled 2 Upper work roll of a rolling mill which is one embodiment of the present invention 3 Lower work roll of a rolling mill which is one embodiment of the present invention 4 Upper work roll of a conventional rolling mill 5 Below a conventional rolling mill Work roll 6 Upper work roll of a rolling mill which is another embodiment of the present invention 7 Lower work roll of a rolling mill which is another embodiment of the present invention

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // B21B 37/00 BBH B21B 37/00 BBH 37/38 116B 117B (72) Inventor Toshitaka Tanaka 1-chome 1, Marunouchi, Chiyoda-ku, Tokyo No. 2 Nippon Kokan Co., Ltd. (72) Inventor Kazuya Fukuoka 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (56) References JP-A-5-185107 (JP, A) JP JP-A-2-268910 (JP, A) JP-A-60-54202 (JP, A) JP-A-57-91807 (JP, A) JP-A-62-282717 (JP, A) JP-A-6-15309 (JP) JP-A-56-131002 (JP, A) JP-A-3-230802 (JP, A) JP-A-63-20106 (JP, A) JP-A-5-177218 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) B21B 13/14 B21B 1/22 B 21B 27/02 B21B 29/00 B21B 31/18

Claims (6)

(57) [Claims] 1. A rolling mill for controlling upper and lower work rolls relative to each other in an axial direction to control a crown and a shape of a material to be rolled, wherein the work rolls have the following crowns. . (A) the crown of the upper and lower rolls has the maximum position of the roll diameter at a position deviated from the center of the roll body length so that the crowns of the upper and lower rolls have the same shape and are symmetrical with respect to the center of the rolling mill,
(B) the roll crown forms a smoothly continuous curve, and the roll diameter monotonously decreases from the maximum position of the roll diameter toward the left and right roll ends; (c) and the curve has the maximum roll diameter. Between the position and the right and left roll ends, at least one inflection point is provided on one or both sides. 2. The rolling mill according to claim 1, wherein a curve forming the crown of the work roll has the following characteristics. (A) From the maximum position of the roll diameter toward both ends, the roll is composed of one or more sine functions having the same or different amplitudes and different wavelengths. At the position of the maximum diameter, the local maximum point of one sine function is connected to the local maximum point of the other sine function. 3. The rolling mill according to claim 1, wherein the rolling mill includes a work roll bending mechanism. 4. A work roll for a rolling mill having the following shape. (A) a roll having a maximum diameter of the roll at a position away from the center of the roll body length, and (b) a curve forming a crown of the roll, wherein a curve forming the crown of the roll faces the right and left roll ends from the maximum position of the roll diameter. The diameter monotonically decreases, and (c) the curve has at least one or more inflection points on one or both of the left and right sides from the maximum roll diameter position to the left and right roll ends. 5. The work roll for a rolling mill according to claim 4, wherein the curve constituting the crown of the work roll has the following characteristics. (A) At the maximum position of the roll diameter, the curve is connected at a maximum point of one sine function and a maximum point of an adjacent sine function, and (b) both ends from the maximum position of the roll diameter. , Each is composed of one or more sine functions having equal or different amplitudes and different wavelengths. 6. The rolling mill according to claim 1, wherein the work roll of the rolling mill is positioned such that the maximum point of the roll diameter of the work roll is near the center of the width of the material to be rolled. A rolling method, characterized in that rolling is performed by relative movement so as to be positioned.