JPH0571323B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The disclosed technology belongs to the technical field of the external structure of a roll such as a work roll installed in a rolling mill to roll a steel plate. <Summary of the gist> The invention of this application has a roll pair of work rolls installed on a stand of a rolling mill via a metal chock, and an intermediate roll or an outer roll of a reinforcing roll above and below the roll pair. This invention relates to a roll for a rolling mill, in which one of the pair of rolls is provided with a roll profile curved in the axial direction over the entire length of its barrel, and a method for manufacturing the same, and in particular, the invention relates to a method for manufacturing the same. The contour of one of the rolls in the pair of rolls is composed of cubic, linear, and constant terms, and is a cubic equation regarding the length distance of the roll in the barrel direction. one roll spans the barrel length of the roll, the roll profile of the other roll is formed point-symmetrically with respect to one barrel, including a portion that is parallel to each other in the barrel length direction, and furthermore, the roll pair is It is made to be able to move freely in the axial direction with respect to the axially fixed roll, and is formed so that the entire length of the barrel of the moved roll pair is longer than the barrel length of the axially fixed roll and remains outside even after the movement. The roll of the rolling mill and the third-order coefficient a of the above-mentioned cubic equation have a plate crown change range of γ, and an axial movement range of ±
This invention relates to a method for manufacturing a roll defined by a=γ/12VB ² when V and plate width 2B. <Prior art> As is well known, with the rise of the automobile industry, rolling precision of rolled steel sheets is increasingly required, and uniformity in the length direction of rolled steel sheets has almost reached the level of perfection. However, the uniformity in the axial direction, that is, the uniformity in the entire width direction of the plate crown, has not reached the level of technology that is completely satisfactory, and various technologies to deal with this are still being developed and researched. There is. Mainly for the modification of the plate crown, control in the substantially convex to flat range is not necessary, and it is strongly desired to be able to control the plate crown from flat to concave. The technical means for plate crown control that has been developed so far is mainly to make rolls such as work rolls, intermediate rolls, and reinforcing rolls curved with respect to the entire length of the barrel, and to provide them with axial movement means. This is what is being done. <Problems to be Solved by the Invention> For example, in the rolling mill of the invention disclosed in JP-A-56-30041, since a quadratic equation is used for the curve regulating the roll profile of the pair of work rolls, the roll The curve of the initial crown of the profile has no minimum and maximum values, and therefore it is naturally necessary to obtain the required plate crown change range of the roll gear upon mechanically limited relative movement in the direction of the barrel. The difference in diameter between the same rolls becomes extremely large, and when applied to the work rolls of a four-tiered rolling mill, for example, contact with the reinforcing rolls becomes uneven, resulting in roll marks. As a matter of course, there were disadvantages such as differences in peripheral surface speed and slip damage, resulting in lower product quality and lower product reliability. The contours of the pair of rolls are point symmetrical, and one roll has a convex crown on one side in the axial direction and a concave crown on the other side.
As shown in Fig. 0, when rolling material 2 is rolled by the pair of work rolls 1 and 1', when the rolls 1 and 1' move relative to each other symmetrically in the axial direction, the roll gap has a convex shape as shown in Fig. 8. , a flat type plate as shown in Figure 9, and a concave type plate as shown in Figure 10, which provide an infinite range of correction functions, but in practice, a convex plate type as shown in Figure 8 is used. Crown control is not necessary, and only plate crown control from the flat type shown in Fig. 9 to the concave type shown in Fig. 10 is required, so unnecessary convex or flat type plate crown control is an unnecessary control capability. There was a useless point with a range. In addition, even if the upper and lower work rolls are moved relative to each other in point symmetry in the axial direction to use a roll curve using a quadratic equation, the components of the plate crown that can be changed will be diamond-shaped or inverted diamond-shaped. It is only possible to change the first-order component related to the distance in the roll axis direction, and the necessary second-order component cannot be changed freely due to the characteristics of roll deflection. The actual rolling process had some drawbacks. Furthermore, as shown in the invention disclosed in Japanese Patent Publication No. 51-7635, in a four-high rolling mill, as shown in FIG. Since the barrel lengths of the work rolls 1, 1' are made equal to the barrel lengths of the reinforcing rolls 3, 3', the deflection of the work rolls 1, 1' is restrained by the reinforcing rolls 3, 3' when controlling the plate crown. The condition changes according to the relative movement of the work rolls 1 and 1', resulting in a disturbance state to the roll bending function, which has the drawback of significantly complicating plate crown control. This has the disadvantage of being extremely complicated and resulting in high costs. <Object of the Invention> The object of the invention of this application is to provide the advantages of sheet crown control through roll bending and axial movement using a structure in which the roll profile of a pair of rolls such as work rolls is curved based on the above-mentioned prior art. However, it is a technical problem to be solved that the extremely large difference in roll diameter causes roll marks, slip marks on the product, and disturbance conditions are imposed on roll bending.
By significantly reducing the diameter difference and using roll bending, the barrel direction movement is unaffected by disturbance conditions, improving product quality and smoothing plate crown control, making it ideal for the machine manufacturing industry. It is an object of the present invention to provide an excellent rolling mill roll that is useful in the field of steel plate forming technology, and a method for manufacturing the roll. <Means/effects for solving the problem> In order to solve the above-mentioned problem, the structure of the invention of this application, which is summarized in the above-mentioned claims, is to solve the above-mentioned problem. Tertiary, primary, The roll profile is formed using a cubic equation regarding the distance in the barrel direction of ^the roll consisting of constant terms, and at this time, the rolling mill plate crown change range γ, the roll Axial movement range ±V, plate width 2B, a=γ/
12VB ² is determined, and the roll contours of one and the other of the roll pair are formed point-symmetrically, including parallel movement in the barrel direction, and by axial movement of their relative positions. The plate crown can be adjusted steplessly from a flat type to a concave type, and the difference in roll diameter required to achieve the desired roll gap plate crown change range is greatly reduced, helping to prevent roll marks and slip scratches. Furthermore, when the roll pair such as work rolls is moved in the axial direction and used in conjunction with roll bending, even after the entire barrel length of the roll pair is moved in the axial direction, the fixed roll pair is It is formed so that it is located outside of the end so that roll bending and roll movement adjustment do not interfere, and each function can be performed independently as designed without giving disturbance conditions to roll bending. The technical conditions were taken into account. <Example> Next, an example of the invention of this application will be described below based on FIGS. 1 to 7. Note that the same parts as in FIGS. 8 to 11 will be described using the same reference numerals. The embodiment shown in FIG. 1 is an embodiment of a four-high rolling mill, in which an upper work roll 1 and a
A lower work roll 1' is disposed, and an upper reinforcing roll 3 and a lower reinforcing roll 3' as external rolls are provided above and below the lower work roll 1', and are mounted on a mill stand via a metal chock or the like (not shown). is the same as the conventional rolling mill. In this embodiment, the roll profile of the roll pair of the upper work roll 1 and the lower work roll 1' is formed by a curved curve based on the cubic equation of the length direction distance of the barrel during their manufacture as follows. , the upper work roll 1 and the lower work roll 1'
for opposing roll contours, respectively, within its barrel length via inflection points 4, 4' to local maximum points 5,
5', and minimum points 6 and 6'. For convenience of illustration, normal shadow lines (hidden lines) are not displayed in all drawings including FIG. 1 to clearly indicate local maximum points, minimum value points, and inflection points. Further, in this embodiment, the upper reinforcing roll 3,
The lower reinforcing roll 3' has an uncurved roll profile and is formed into a columnar straight shape, and the roll outlines of the upper work roll 1 and the lower work roll 1' are emphasized for the sake of illustration. Furthermore, the illustrated embodiment is shown in a state where no rolling force is applied. In the mode of a two-high rolling mill, the difference in the roll contours of the upper and lower work rolls 1, 1' is given as a roll gap, but in the four-high rolling mill and six-high rolling mill, the work roll, Alternatively, in an embodiment in which a curved roll profile is provided to a pair of intermediate rolls, the curved roll profile curve is applied to only one pair of rolls, and a straight, flat linear roll profile is provided to the other roll pairs. This results in twice the amount of plate crown control than in the two-high rolling mill embodiment. Therefore, the curved shape of the roll profile of the pair of upper and lower work rolls 1 and 1' of the four-high rolling mill shown in FIG. 1 will be described in detail with reference to FIGS. 2 to 5. As shown in Fig. 2, the formula for the longitudinal distance of the barrel, which defines the curved shape of each roll profile of the roll pair, is expressed as the maximum value 5,
If the expression having the minimum value 6 is given as a cubic expression y=ax ³ +cx+d consisting of the barrel direction axis x, the axis y perpendicular to this, the cubic, linear, and constant terms, the equation is shown in Fig. 2. It will have the following characteristics. dy/dx=3ax ² +c, d ² y/dx ² =6ax Point giving local maximum value, local minimum value x=±√−3 Point giving inflection point x=0 And, assuming the body length of the roll barrel to be 2L ,
It has a maximum value of 5 and a minimum value of 6, and the neutral point of the roll is translated by w in the length direction of the barrel, and the ends 9, 1
The roll profile of one roll 1, which has minimum values 5 and 6 between 0 and 0, is as shown in FIG. The roll profile of the other roll 1' with a body length of 2L, which has a maximum value of 5' and a minimum value of 6' between them, is as shown in Figure 4, and these are schematically expressed as neutral points about the same axes X and Y. If you arrange it so that it is on the Y axis, it will look like Figure 5,
x=X+w for upper roll 1, x for lower roll 1'
= X−w, so the roll contour of upper roll 1
Y ₁ and the roll profile Y ₂ of the lower roll 1' are expressed by the following equations (1) and (2), respectively. Y ₁ =a(X+w) ³ +c(X+w)+d ₁ (1) Y ₂ =a(X-w) ³ +c(X-w)+d ₂ (2) Moreover, as shown in FIG. = 0, then Y ₁ −Y ₂ =h, aw ³ +cw+d ₁ −{−aw ³ −cw+d ₂ }=h, that is, 2aw ³ +2cw+d ₁ −d ₂ =h (3) Then, the barrel is neutral in the axial direction. The shape ΔY of the roll gap at the position is ΔY=Y ₁ −Y ₂ = {a(X ³ +3wX ² +3w ² X+w ³ ) +c(X+w)+d ₁ } −{a(X ³ +3wX ² +3w ² X−w ³ ) +c(X-w)+ _d2 }= ^6awX2 + ^2aw3 +2cw+ _d1 - _d2 = ^6awX2 +h (4) Next, as shown in Fig. 6, the upper roll 1 and lower roll 1' of the work rolls are moved from the neutral position shown in Fig. 5 to the right direction v and the left direction equidistantly to v, respectively, point-symmetrically. (this is called parallel movement on the day crease side), the roll contour is Y ₁ ′=a{(X-v)+w} ³ +c{(X-v)+w}+d ₁ (1′) Y ₂ ′ = {a(X+v)-w} ³ +c{(X+v)-w}+d ₂ (2') And the roll gap shape ΔY' after axially symmetrical translation toward the day crease side is ΔY′=Y ₁ ′−Y ₂ ′ = {a(X+(w−v)} ³ +c{X+(w−v)
}+
d ₁ -a{X-(w-v)} ³ +c{X-(w-
v)}+ _d2 =6a(w-v) ^X2 +2a(w-v) ³ +2c(w-v)+d1 _{- d2} =6a(w-v)
X ² +2a {−3vw ² +3v ² w−v ³ } −2cv+h (5) In particular, it can be seen that a flat roll gap shape can be obtained by performing parallel movement on the day crease side equal to the movement amount w of the neutral point. Ru. In the case of parallel movement in the opposite direction symmetrically to the axial direction (this is called parallel movement on the increase side), by substituting (-v) for v in the above equation (5), a roll gap shape can be obtained. However, as is clear,
In this case, a concave roll gap shape given by a quadratic equation regarding the distance in the barrel direction is obtained. Then, when performing parallel movement to the day crease side and when performing parallel movement to the increase side, if the plate width is 2B and the amount of parallel movement v = ±V, the plate crown change range γ
is as follows. That is, in the case of parallel movement on the day crease side, roll gap at v=+V, X=B: α ₁ Roll gap at v=+V, X=0: α ₂ Plate crown at v=+V: Δα , Δα=α ₂ −α ₁ =−6a(w−V)B ² (6) Similarly, in the case of parallel movement on the increase side, the roll gap at v=−V and x=B: β ₁ Roll gap at v = -V, x = 0: β ₂ Plate crown at v = -V: Δβ Δβ = β ₂ -β ₁ = -6a (w + V) B ² (7) Therefore, the plate crown change range γ is expressed as γ=Δα−Δβ=12aVB ² . From the above, the plate crown change range γ of the rolled material 2 is determined by the equation regarding the limit value V of the amount of axial movement from the axial neutral position of the roll to the left and right, the plate width 2B, and the distance in the barrel direction of the curve of the roll profile. It can be seen from equation (8) that it is determined by the coefficient a of the cubic term, and is completely unrelated to the coefficient c of the constant term, the constants d ₁ and d ₂ , or the amount of parallel movement w of the neutral point. Here, it is known that the roll pairs of the work roll, reinforcing roll, and intermediate roll generally have a convex roll gap distribution due to the rolling reaction force.
It has been found that the main component in the formula is a quadratic term of the lengthwise distance of the barrel. On the other hand, from the above equations (4) and (5), if the upper work roll 1 is moved in parallel from the day crease side to the increase side, that is, from right to left, symmetrically, the lower work roll 1 1' is translated from left to right, it can be seen that the roll gap distribution changes arbitrarily from the convex shape shown in FIG. 8 to the concave shape shown in FIG. 10 depending on the coefficient of the second-order term in the equation. Therefore, the correction of the convex roll gap, which changes depending on the deflection of the roll depending on the rolling conditions, can be made accurately by at least controlling it from the flat shape shown in Figure 9 to the concave shape shown in Figure 10. Modifications can be made to this. Therefore, it is desirable to obtain a concave roll gap as large as possible, and from this point of view, the maximum shape control ability can be obtained by taking the axial movement amount of w = V from equation (6). I understand that. By the way, when a roll that is curved over the entire length of the roll barrel is used, the peripheral surface speed of the roll changes depending on the change in the roll diameter, but this also affects the lubrication conditions between the rolled material and the roll. It was concluded that this difference would result in a difference in surface roughness and surface gloss on one side of the rolled material, significantly deteriorating the product properties. Therefore, when there is a large change in roll diameter, the rolling speed changes on the upper and lower surfaces of the rolled material, causing upward rolling and downward rolling, which also reduces confidence in product quality. In order to deal with this, it is necessary to minimize the diameter difference of the curved roll contour, but in the invention of this application, the cubic equation is calculated so that both the maximum and minimum values of the curve of the roll contour are within the roll barrel. Equation (8) shows that the first-order coefficients can be given, and that they do not affect the variation range γ of the plate crown of the rolled material in any way.
It is clear from this. Therefore, in the following, the required plate crown change range γ
Using specific numerical values, we will examine how the difference in roll diameter can be reduced between the use of the roll profile curve of the prior art and the use of the roll profile curve according to the invention of this application. In the embodiment shown in Fig. 1, the body lengths 2L of the barrels 1 and 1' of the upper and lower work rolls are both 2200 mm, the horizontal translation amount V is 100 mm, the plate width 2B is 2000 mm, and the required plate crown change range. When γ is 1 mm, for example, according to the means of the conventional aspect of the invention described in JP-A-56-30014, the upper work roll 1 has a convexity of y ₁ =a ₁ x ² +d ₁ on one side in the axial direction. A concave crown outline of y ₂ = a ₂ x ² + d ₂ is provided on the opposite side of the crown outline, and the initial crowns of the lower work roll 1' have approximately the same shape and are point symmetrical to each other. It is. In the following discussion, assuming that the symbols follow equations (1) to (8), Y ₁ = a ₁ (X+w) ² + d ₁ (1″) Y ₂ = a ₂ (X−w) ² + d ₂ (2″) X=O: Y ₁ − Y ₂ = h (a ₁ − a ₂ ) w ² + d ₁ − d ₂ = h (3″) ΔY=Y ₁ − Y ₂ = (a ₁ − a ₂ )X ² +2 _{( a 1 w} ⁺ _{a 2 w} ⁾ _{_} ) ΔY _′ = (a ₁ − a ₂ ) X ² + ₂ (a ₁ + _{a 2 )} (w ⁻ v) Δα=α ₂ −α ₁ =−(a ₁ −a ₂ )B ² −2(a ₁ +a ₂ )(w−V)B(6) Δβ=β ₂ −β ₁ =−(a ₁ −a ₂ )B ² -2 (a ₁ + a ₂ ) (w + V) B (7) γ = Δα - Δβ = 4 (a ₁ + a ₂ ) VB (8) Substituting γ = 1 mm, V = 100 mm, and B = 1000 mm, we get a ₁ + a ₂ = 4 x 100 x 1000 = 10 ^-5 / 4 Therefore, for simplicity, the amount of movement of the neutral point W =
Considering the case of 0, the contour of the right half of the upper roll Y _1R = a ₁ x ² + d ₁ The contour of the left half of the upper roll Y _1L = -a ₂ x ² + d ₁ Therefore, at the right body end of the upper roll, Y _1R = a ₁ L ² + d ₁ , Y _1L = -a ₂ L ² + d ₁ at the left body end of the upper roll, and since L = 1100 mm, the roll diameter difference is 2 x (a ₁ + a ₂ ) L ² = 2 x 10 ^-5 ×1100 ² /4 = 6.05mm is required. Moreover, the above-mentioned drawback of this prior art can be clearly read in equations (4'') and (4). In other words, the coefficient of the quadratic term of x is completely unrelated to the axial movement amount v, and the roll Characteristic values of contour curve a ₁ , a ₂
If is determined, it will only take a constant value, and the only thing that can be changed by the axial movement amount V is the coefficient of the first-order term of x, and only diamond-shaped or inverse diamond-shaped plate crown control can be performed. I understand. If the above process is applied, for example, to a work roll having a roll profile proportional to the cubic term of the patent application No. 61-103941, the applicant's earlier invention, the roll curve y = ax ³ + d, w = 0, a=1/12×100×1000 ² =10 ^-8 /12, X=x, so upper roll contour Y ₁ = ax ³ + d ₁ = 10 ^-8 ×x ³ +/12d ₁ Maximum value Y _1nax = 10 ^-8 ×1100 ³ /12 + d ₁ = 1.109 + d ₁ (mm) Minimum value Y _1nio = 10 ^-8 / 12 × (-1100) ³ + d ₁ = -1.109 + d ₁ (mm) Roll diameter Difference 1.109×2×2=4.436mm On the other hand, when applying the means of the invention of this application, roll curve y=ax ³ +cx+d, w=V (=100) a=1/12×10 ^-8 poles Point giving the value x=±√−3 Select the coefficient c so that the point giving the extreme value is at x=±500. -c=3a×500 ² =3×10 ^-8 ×500 ² /12 =25×10 ^-4 /4 Upper roll contour Y ₁ =10 ^-8 (X+100) ³ /12 -25×10 ^-4 (X+100) /4+d ₁ When X=1100 Y ₁ =0.6900+d ₁ When X=-1100 Y ₁ =-0.2083+d ₁ When x=500, that is, when X=400 Y ₁ =-0.2083+d ₁ x=-500, That is, when X = -600, Y ₁ = 0.2083 + d ₁ roll diameter difference (0.6900 + 0.2083) x 2 = 1.7966 mm Then, specific examples of the above two conventional embodiments and the embodiment of the invention of this application are summarized. As shown in Table 1 below, it can be seen that the roll diameter difference that gives the plate crown change range γ of the roll gap of the invention of this application is significantly reduced, and as a result, the occurrence of roll marks and slip scratches can be prevented. It is clearly seen that it is effective.

[Table] Next, in the embodiment shown in FIG. 7, the upper intermediate roll 11 and the lower intermediate roll 11' of a six-high rolling mill have cubic, linear, and constant terms, as in the four-high rolling mill described above. In this example, the maximum value and the minimum value exist within the entire length of the barrel. It is also clear that the effects of the embodiment shown in FIG. 7 are the same as those of the embodiment shown in FIG. In this embodiment, the work roll 1,
1' and reinforcing rolls 3, 3' are formed into flat straight rolls. Furthermore, in the embodiment shown in FIGS. 1 and 7, when the pair of rolls having the cubic roll profile described above is shifted in parallel in the barrel direction, both ends 9, 10, 9', and 10' are flat. It is formed with a long barrel length that covers the fixed roll of a pair of straight rolls even after it moves in the axial direction.
Therefore, when axial movement in the barrel direction and roll bending are used together, there is no change in the contact state between the axially fixed roll and the axially moving roll, so there is no change in the restraint state of the deflection of both rolls. It can be seen that no disturbance is caused to the roll bending effect by adjusting the barrel direction movement of the axially moving roll, and that there is no effect on plate crown control by roll bending. It should be noted that the embodiments of the invention of this application are not limited to the above-mentioned embodiments, for example, and can be applied to rolling mills with six or more stages, and
Various embodiments can be adopted, such as application to work rolls of a six-high rolling mill. <Effects of the Invention> As described above, according to the invention of this application, at least one roll pair of a rolling mill is provided with a cubic roll profile having a maximum value and a minimum value within the roll barrel. As a result, the roll diameter difference in the roll contour that provides the plate crown change range of the work roll gap is significantly reduced, and the peripheral surface speed change of the rolls is also small, preventing uneven contact between the contacting rolls and causing roll marks and slip scratches. First, it has the excellent effect of improving the reliability of the product. In addition, since the convex roll gap can be corrected in a manner that matches the actual rolling conditions and can be adjusted from a flat type to a concave type, the convex roll gap for the plate crown changes depending on changes in rolling conditions. The excellent effect of not causing problems such as elongation and eliminating the need to provide unnecessary plate crown shape control ability is achieved. Moreover, even though a roll having a curved roll profile is used over the entire length of the roll barrel, there is little change in the roll peripheral speed, and even when the invention of this application is applied to a work roll, the rolling material and roll There will be no unevenness in the lubrication conditions between the rolling materials, and there will be no unevenness in surface roughness or surface gloss on one side of the rolled material, which has the excellent effect of significantly increasing product precision. be done. Furthermore, as mentioned above, even though the upper and lower rolls are in an interpolating relationship, the difference in the diameter of the rolls is small, so even when the invention of this application is applied to work rolls, there is No upward or downward slope is formed, and from this point of view as well, an excellent effect is achieved in that the reliability of the product is improved. Furthermore, even if roll bending is used in combination with the upper and lower rolls being moved in the axial direction, both ends of the moving rolls will be located further outside of both ends of the fixed rolls, and therefore the reinforcing rolls will Since there is no change in the contact state between the work roll and the work roll, and there is no change in the restraint state of roll deflection, no disturbance conditions are given to the roll bending effect, and the roll bending effect for plate crown control is provided as designed. This is an excellent effect. Therefore, when manufacturing a roll, as in the dependent invention of the above-mentioned claims, the coefficients of the cubic term and the linear term of the cubic curve forming the contour of the roll are determined. It is possible to specifically specify the optimal roll curve that matches the rolling conditions, and it is also possible to minimize the roll diameter difference necessary to express the plate crown change range of the roll gap. As a result, an excellent effect is achieved that does not cause roll marks or slip marks on the product. It also has the effect of making it possible to control the secondary components of the sheet crown, which are most necessary in actual rolling.

[Brief explanation of drawings]

1 to 7 are explanatory diagrams of embodiments of the invention of this application, FIG. 1 is a schematic front view of one embodiment, FIG. 2 is a graph of a basic cubic curve that provides a roll contour, Figure 3 is a graph showing how the roll contour is imparted to the upper roll of the roll pair, Figure 4 is a graph showing how the roll contour is imparted to the lower roll of the roll pair, Figure 5 is a schematic front view of the roll pair, and Figure 6 is the upper roll and the lower roll. A graph showing the parallel movement of the rolls, Fig. 7 is a schematic front view of another embodiment equivalent to Fig. 1, Fig. 8 is a schematic front view of convex plate crown control, and Fig. 9 is flat plate crown control. FIG. 10 is a schematic front view of concave plate crown control, and FIG. 11 is a schematic front view of plate crown control based on the prior art. 1, 1'... Working roll, 3, 3'... External roll, 4, 4'... Inflection point, 5, 5'... Maximum value,
6,6'...minimum value.

Claims (1)

[Claims] 1. In the roll of a rolling mill in which external rolls are provided above and below a pair of work rolls, and one of these roll pairs has a curved roll profile over the entire length of the barrel, roll contour y
is a cubic equation y=ax ³ +cx+d regarding the distance in the roll axis direction consisting of cubic, linear, and constant terms, and consists of a part having its maximum value and minimum value, and the coefficient a of the cubic term and the coefficient a of the first The coefficient c of the term is defined as the plate crown change range γ of the rolling mill, the roll axial movement range ±V, the plate width 2B, and the x coordinate of the point giving the extreme value ±
When x _P , a=γ/12VB ² and c=−3ax _P ² are set so that the roll contours of one and the other of the roll pair are equal to each other, including the parallel movement in the barrel length direction. A roll of a rolling mill characterized by being formed point-symmetrically. 2. In the roll of a rolling mill in which external rolls are provided above and below a pair of work rolls, and one of these roll pairs has a curved roll profile over the entire length of the barrel, the roll profile y of the roll pair
is a cubic equation y=ax ³ +cx+d regarding the distance in the roll axis direction consisting of cubic, linear, and constant terms, and consists of a part having its maximum value and minimum value, and the coefficient a of the cubic term and the coefficient a of the first The coefficient c of the term is defined as the plate crown change range γ of the rolling mill, the roll axial movement range ±V, the plate width 2B, and the x coordinate of the point giving the extreme value ±
When x _P , a=γ/12VB ² and c=−3ax _P ² are set so that the roll contours of one and the other of the roll pair are equal to each other, including the parallel movement in the barrel length direction. Furthermore, the pair of rolls is made axially movable relative to the fixed roll in the axial direction, so that even after the entire length of the pair of movable rolls is moved in the axial direction from that of the fixed roll in the axial direction, the end portion remains unchanged. A rolling mill roll characterized by being formed to lengthen outward. 3. The roll profile of a roll pair is a cubic equation regarding the distance in the roll axis direction consisting of cubic, linear, and constant terms, and consists of a portion having its maximum value and minimum value, and the roll contour of one roll pair and the other roll of the roll pair are In a method for manufacturing a roll for a rolling mill in which the contour is formed point-symmetrically with respect to the barrel length direction, the coefficient a of the cubic term and the coefficient c of the linear term of the roll profile curve y=ax ³ +cx+d are Rolling mill plate crown change range γ, roll axial movement range ±V, plate width 2B,
A method for manufacturing rolls for a rolling mill, characterized in that the x coordinate of a point giving _an extreme value is determined as follows: a=γ/12VB ² c=−3ax _P ² .