JP2908653B2 - Method of manufacturing metal plate with small edge drop - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal sheet having a good cross-sectional shape and a good planar shape.

[0002]

2. Description of the Related Art In recent years, demands on the properties of metal sheets of various materials manufactured by rolling (hereinafter referred to as "rolled sheets") have become more and more strict, and the thickness and shape of the sheets have been increasing. It is desired to control the accuracy.

Generally, when a metal plate is rolled, a work roll receives a reaction force from the metal plate and deforms flat. However, the amount of deformation decreases sharply near the edge of the plate width. At the same time, the plastic flow of the material occurs at the end of the sheet width due to the absence of the restraining force outward in the sheet width direction. Therefore, as shown in FIG. A shape defect called edge drop, which sharply decreases, occurs. In order to give the precision of the required thickness as a product to the rolled sheet where this edge drop occurs, it is necessary to perform a process called trimming to cut off the end of the sheet, which reduces the production efficiency and the yield. Inviting.

As a method of preventing the occurrence of the edge drop, there is known a method of rolling using a work roll (hereinafter, referred to as a tapered roll) whose end is tapered as shown in FIG. According to this method, the roll deformation is canceled out by the taper, and as shown in FIG. 1 (b), the metal plate can be rolled without deforming the width end thereof.
Edge drop can be prevented from occurring. In addition to rolling using a taper roll vertically, for example, a method using a taper roll only in one of the upper and lower sides (FIG. 3 (a))
Alternatively, there is a method in which rolls having only one end tapered are symmetrically arranged at the top and bottom, and rolling is performed while shifting the work roll in accordance with the plate width (FIG. 3B). In addition,
These figures show a state in which the work roll is not deformed by the reaction force of the metal plate for convenience, but the cross section of the material to be rolled (metal plate) is actually rectangular.

On the other hand, when a metal plate is rolled, there is no restriction in the width direction at the end, so that the metal plate is outwardly directed in the width direction (from the center to the end).
Plastic flow occurs. Therefore, although the above-described method can suppress the occurrence of edge drop, the elongation at the center becomes larger than the end of the plate, and excessive tension is generated only at the end. There is a problem that the shape deteriorates.

In recent years, a rolling mill (usually referred to as a minimum-edgedrop mill, abbreviated as ME mill) has been developed and put into practical use, in which a work roll is flexed in a horizontal direction for the purpose of controlling plastic flow in the width direction. (Plasticity and Processing, Vol.
31-352 (1990), pp. 632-638, Proceedings of the 39th Joint Lecture on Plastic Working, 593-596). The rolling mill is a rolling mill for the purpose of offsetting a work roll having an extremely small diameter, bending the work roll horizontally by a support roll, and controlling edge drop. 4
As shown in (b) and (c), bending the work roll in the horizontal direction generates a frictional force in the sheet width direction, and the plastic flow during rolling of the material changes in the width direction. ing. As a result, it is suggested that by suppressing the elongation deviation in the width direction, it is possible to change the thickness distribution in the width direction while keeping the shape of the rolled material favorable.

FIG. 4 is a plan view showing the horizontal deflection of the roll, and the arrow (→) in the figure indicates the direction of the rotation vector of the roll. 4 (a) is a state in which the roll is not bent, FIG. 4 (b) is a state in which the roll is bent to the entrance side in the rolling direction, and FIG. 4 (c) is a state in which the roll is bent to the exit side in the rolling direction. in this way,
As shown in FIG. 4 (b) or (c), the vector in the rotation direction of the roll is inward or outward, respectively, as compared to the normal rolling, and the velocity vector in the width direction of the roll is different, so that the friction in the width direction of the roll is A force is generated, causing a plastic flow of the material.
However, this method requires a special roll arrangement for bending the roll and large-scale incidental facilities,
It is difficult to control the amount of roll deflection, and it is also difficult to increase the amount of roll deflection. Therefore, it is extremely difficult to arbitrarily control the plastic flow of the material in the sheet width direction.

[0008] In addition, rolling is performed using a work roll, which has been proposed by the present applicant, and at least a portion of the rolled material in contact with the end of the width of the roll is polished in a spiral shape. A method of applying a shearing force from the center of the width to the end of the sheet width (Japanese Patent Application No. 3-310307), in which the upper and lower work rolls are singly or paired with a backup roll and intersect in a plane parallel to the rolling surface. In a method of rolling a metal plate (in this specification, both are referred to as “roll cross rolling”), a method of rolling by changing the friction coefficient between a work roll and a metal plate in the axial direction of the work roll. (Japanese Patent Application No. 4-252392). In both cases, a shear force is applied in the width direction of the plate to prevent the occurrence of shape defects.

[0009]

According to various cold rolling methods for controlling edge drop, a large tensile force acts in the longitudinal direction of rolling near the edge of the sheet, so that the rolled material is broken and the edge of the sheet is broken. There is a problem that a shape defect occurs.

[0010] An object of the present invention is to prevent the occurrence of shape defects and plate breakage by a relatively simple method in a rolling method for controlling edge drop.

[0011]

The gist of the present invention resides in the following (1) and (2).

(1) A metal plate is rolled using a work roll having a spiral polished surface on the surface and having a tapered portion in contact with a plate width end of a rolled material, and the plate width is reduced in a rolling backward region. A method for producing a metal plate with small edge drop, which is rolled by applying a shear force inward in the direction.

(2) Using a work roll having a tapered portion in contact with an end portion of the rolled material in the width direction, changing the friction coefficient between the work roll and the metal plate in the axial direction of the work roll. A method for producing a metal sheet having a small edge drop, wherein the metal sheet is subjected to roll cross rolling and subjected to an inward shear force in the sheet width direction to perform rolling.

[0014]

[Action]

(A) A method for applying a shearing force in the width direction of the material will be described.

1) Rolling is performed by using a work roll having a spiral polishing stitch.

The roll having a spiral polishing stitch means a roll having a spiral polishing stitch as shown in FIG. 5 (a). Although the actual surface of the roll is very finely ground by polishing, in FIG. 5 and FIGS. 6 and 7 described below, the surface roughness is exaggerated for convenience of explanation. FIGS. 5 (a), 6 and 7 are views as seen from the outside in the rolling direction. In this roll, spirals having different inclination directions are attached to the entire barrel with the center of the barrel as a boundary. However, as shown in FIGS. 6 and 7, there are various modes for spiral polishing and use of the spiral polishing roll. Is possible.

The polished eyes are microscopically intermittent, but macroscopically, they are spirally connected along the outer periphery of the roll. Such a roll is referred to as a “spiral polishing roll” in the present invention.

FIG. 8 is a diagram schematically showing the relationship between rolls and rolled materials during rolling. As shown in the figure, the plate thickness t ₁ to t ₂
If the speed of the rolled material on the roll entrance side (point A) is v ₁ and that on the exit side (point B) is v ₂ , then v ₁
<A v _2. The point (point N) at which the speed v of the rolled material becomes the same as the roll peripheral speed V is called a neutral point, and from this point forward (the roll exit side) is called the advanced zone, and backward (the roll entrance side) is called the reverse zone. In the reverse region on the entry side from the neutral point N, the speed v _{1 of the} rolled material
Is smaller than the roll peripheral speed V, so that a force acts to pull the rolled material toward the roll, and in the advanced region on the exit side from the neutral point N, the speed v _{2 of the} rolled material is larger than the roll peripheral speed V. The rolled material exerts a force that pulls it back in the roll direction. The rolled material is subjected to inward or outward shearing force in the sheet width direction by the action of the directionality and the spiral polishing of the roll surface.

That is, a shearing force can be exerted in the width direction of the metal plate by using a spirally polished work roll and selecting the direction of spiral polishing.

The shearing force applied to the surface layer of the rolled material in the reverse travel region does not need to cover the entire width of the upper and lower surfaces of the rolled material. That is,
In the present invention, an inward shearing force is applied only to both end portions of the sheet width, an inward shearing force is applied to any left or right half or less of the sheet width, either the upper surface or the lower surface of the rolled material. The object can also be achieved by a method in which an inward shearing force is applied to the surface.

FIG. 6 shows some combinations of work rolls in which both ends of the barrel (including a portion in contact with the plate width end) are spirally polished. In these cases, polishing of the center of the roll is optional. FIG. 6A shows the case where the center of the roll is polished normally, FIG. 6B shows the case where the center of the roll is brightly polished to a mirror surface, and FIG.
In any of these cases, an inward shearing force acts on both ends of the rolled material in the sheet width direction, and plastic flow outward in the sheet width direction can be prevented.

FIG. 7 shows an example in which the polishing state of the upper and lower work rolls is changed. (a) is spiral polishing only on the left and right halves of the upper and lower rolls, and when the rest is normal polishing,
(b) and (c) are cases where a spiral polishing roll is used for only one of the upper and lower ones, and the other is a normal polishing roll. When a metal plate is rolled by combining work rolls in this way, at least both ends of the rolled material are subjected to an inward shear force in the plate width direction, and the outward plasticity in the plate width direction, which is one of the causes of edge drop. Flow can be prevented.

2) In roll cross rolling, rolling is performed by changing the friction coefficient between the work roll and the metal plate in the axial direction of the work roll.

FIG. 9 shows a case where roll cross rolling is performed at a cross angle θ without changing the friction coefficient between the upper work roll and the upper surface of the metal plate and the lower work roll and the lower surface of the metal plate in the axial direction of the work roll. 2 shows the relationship between the metal plate and the upper and lower work rolls. FIG. 9A is a plan view, and FIG.
(b) is a cross-sectional view of the direction of the shearing force acting on the upper and lower surfaces of the metal plate as viewed from the entry side in the rolling direction. However, in FIG. 9 and FIG. 10 (b), which will be described later, the thickness direction is shown as being enlarged as compared with the width direction.

As shown in FIG. 9A, there is a deviation of the angle θ between the speed vector in the roll rotation direction and the speed vector in the rolling direction. Relative slip occurs. As a result, the upper surface of the metal plate acting shear forces F ₁ towards the end C from the end A, the lower surface of the metal plate acting shear forces F ₂ towards the end A from the end C. At this time, if the coefficient of friction between the work roll and the metal plate is the same on the upper and lower surfaces of the metal plate and also in the width direction of the metal plate, the shear forces F ₁ and F ₂ in the width direction of the metal plate are:
The result is as shown in FIG. That is, F ₁₁ = F ₁₂ = F ₁₃ ,
F ₂₁ = F ₂₂ = F ₂₃ , and F ₁₁ = F ₂₁ , F ₁₂ =
Since in _{F 22, F 13 = F 23} , the plate width direction of the force at the upper and lower surfaces of the metal plate cancel each other. Therefore, at the ends A and B of the metal plate, only the plastic flow in the width direction of the plate due to the absence of the restraining force occurs to the ordinary degree.

FIG. 11 shows an example of a roll in which the surface roughness is changed in the width direction. FIG. 10 shows the use of a roll as shown in FIG. 11 to determine the friction coefficient between the upper and lower surfaces of the metal plate and the work roll. It is an example showing a relationship between a metal plate and upper and lower work rolls when performing roll cross rolling at a cross angle θ while changing the work roll in the axial direction. FIG. 10 (a) is a plan view, and FIG. 10 (b) is a cross-sectional view of the direction of the shearing force acting on the upper and lower surfaces of the metal plate viewed from the rolling direction entry side. In this method, the surface roughness of the upper work roll is large at the end A and small at the end C, and the surface roughness of the lower work roll is small at the end A and large at the end C. , And the rolling coefficient is changed in the axial direction of the work roll.

At this time, a shear force F ₁ from the end A to the end C acts on the upper surface of the metal plate, and a shear force F ₂ from the end C toward the end A acts on the lower surface of the metal plate. I do. However, when looking at the sizes of F ₁ and F _{2 in} the plate width direction, FIG.
As shown in the above, F ₁₁ <F ₁₂ <F ₁₃ , F ₂₁ > F ₂₂ > F ₂₃ , and F ₁₁ <F ₂₁ , F ₁₂ = F ₂₂ , and F ₁₃ > F ₂₃ . Therefore, from the relative relationship between the forces on the upper and lower surfaces of the plate,
An inward force acts on both the end A and the end C.

As described above, by applying an inward shearing force in the width direction at the end of the metal plate, an inward plastic flow in the width direction can be generated. That is,
It is possible to offset the plastic flow of the metal plate caused by the rolling.

Next, the reason why the plastic flow can suppress the shape defect generated in the metal plate after rolling will be described.

The ear wave or middle elongation is caused by elongation in the longitudinal direction being different in the width direction of the board. Therefore, if the elongation in the longitudinal direction is made closer to a uniform state in the board width direction,
Ear waves or middle elongation can be reduced or even prevented.

The present invention utilizes the inward shear force in the width direction at the end of the metal plate generated by the above-described method to promote longitudinal elongation at the end of the metal plate. It is. In this way, it is possible to perform rolling so that the elongation in the longitudinal direction becomes equal in the width direction of the sheet, and as a result, shape defects can be reduced or further prevented.

In order to apply an inward shearing force in the width direction of the plate, the present invention uses "a spiral polishing roll".
Or a method of "changing the coefficient of friction between the work roll and the metal plate in the axial direction of the work roll". As a method of changing the friction coefficient between the work roll and the metal plate in the roll axis direction, any method such as changing the temperature of the roll in the axial direction or changing the temperature of the metal plate in the width direction is used. Although it does not matter, it is indispensable for the operation of cold rolling, considering that it is not necessary to introduce large-scale new equipment and to consider the influence of thermal expansion of metal plates or rolls. It is preferable to change at least one of the types, the temperature, the concentration, the viscosity, the emulsion particle size and the supply amount of the rolling oil and the surface roughness of the work roll itself in the roll axis direction.

Generally, when the surface roughness of the work roll is constant, the temperature of the rolling oil is increased,
The friction coefficient can be increased by performing at least one of the operations of lowering the viscosity, reducing the emulsion particle size, or decreasing the supply amount. Further, if the various conditions of the rolling oil are kept constant, the surface roughness of the work roll may be increased. If this is performed in the roll axis direction of the roll cross rolling, plastic flow in the width direction of the metal plate occurs at the end of the metal plate, so that defective shape can be prevented.

For example, if rolling oils having different temperatures are used, the coefficient of friction between the metal plate and the work roll also differs. Therefore, when the work rolls are arranged and roll cross rolling is performed as shown in FIG. If a higher temperature rolling oil is supplied to the end A side of the upper surface than the C side and the lower surface is rolled under the opposite condition, an inward force acts on the rolled material in the sheet width direction, and the shape is defective. Can be alleviated.

The method of the present invention comprises the steps of:
It is not limited by the material of the work roll or the kind of the rolling oil. When the friction coefficient is changed in the axial direction, the coefficient of friction may be changed gradually, or may be changed regionally so as to have one or more displacement points at the center of the plate or at other places.

(B) When rolling is performed using a taper roll,
The fact that edge drop can be prevented will be described.

The taper roll referred to in this specification is a roll having a taper (inclined) such that the diameter of the taper decreases toward the end of the roll as shown in FIG. This taper is
An arc shape as shown in FIG.

As described above, when a metal plate is rolled by a normal roll, the work roll receives a reaction force from the metal plate and deforms flat. However, the amount of deformation decreases sharply near the edge of the sheet width, and conversely deforms the metal sheet. Therefore, even if the plastic flow in the sheet width direction can be prevented by the above-described method, an edge drop still occurs in the rolled sheet.

When rolling is performed using a taper roll, the rolling force acting on the end of the sheet width during rolling is smaller than that of other parts, but the work roll is deformed, so that a sharp deformation at the end of the sheet width occurs. The decrease in volume is offset by the taper and the roll gap profile becomes rectangular. In this way, since the cross-sectional shape of the metal material at the time of rolling can be made rectangular, it is possible to prevent edge drop that occurs when the width end portion is deformed by the work roll.

By performing the methods (A) and (B) at the same time, it is possible to manufacture a metal plate free from edge drops and free from shape defects. Therefore,
As a mode of using the taper roll, there is a method in which only one of the upper and lower sides is a taper roll, a method in which a roll having a taper only on one side is symmetrically arranged in the upper and lower directions, and the like. Can be applied.

At this time, the taper needs to exist at least at a portion in contact with the end of the width of the metal plate to be rolled.
When the shearing force in the sheet width direction is generated by a spiral polishing roll as shown in FIG. 12, this spiral polishing must also be present at least in a portion in contact with the edge of the sheet width, but in other portions, There is no particular limitation.

Hereinafter, effects of the present invention will be described based on examples.

[0043]

EXAMPLE 1 Cold rolling of a metal plate was performed using rolls having an arc-shaped taper having a curvature of 25 mR at the end as shown in FIG. 13 as upper and lower work rolls. At this time, the upper and lower work rolls were spirally polished only at the tapered portion, and were arranged such that an inward shearing force was applied in the backward movement region of the metal material (arrangement in FIG. 5). Both the upper and lower work rolls have a surface roughness of 0.2 μm in the direction perpendicular to the polished line in the normal polishing part without taper, and Ra in the spiral polishing part.
Is 1.0 μm, and the polishing angle (α in FIG. 5) is 45 ° with respect to the circumferential direction of the roll.

As a rolling oil, the viscosity at 40 ° C. is 40 cSt
Using a 2.0mm thick, 1200mm wide steel plate with a work roll diameter of 550mmφ and a backup roll diameter of 15
It was rolled with a 4Hi rolling mill of 00 mmφ. The rolling reduction was 30%, and the rolling speed was 450 m / min.

FIG. 15 shows the thickness deviation with reference to the center of the plate.
FIG. 16 shows the steepness calculated from the stretching difference from the center of the plate at a certain position in the plate width direction. FIG. 15 shows the cross-sectional shape in the plate width direction of the metal plate after rolling, and FIG. 16 shows the planar shape. The steepness is a value obtained by converting the difference in elongation in the rolling direction between each position in the width direction of the sheet and the center of the sheet. A negative steepness indicates a state in which the elongation is smaller than that in the center of the sheet (so-called middle elongation). Where the steepness is positive indicates that the elongation is greater than the center of the plate.

Rolling was performed under the same conditions using a roll having a tapered work roll, but having a polishing line parallel to the circumferential direction of the roll (normal polishing). The results are also shown as Δ in FIGS. 15 and 16.

FIG. 15 shows that a rolled sheet having a good cross-sectional shape without any edge drop can be obtained when rolled by the method of the present invention, as in the case of rolling using a conventional tapered work roll. . On the other hand, FIG. 16 shows that the difference in elongation in the plate width direction is small and the steepness is improved.

Incidentally, the difference in elongation in the sheet width direction also affects the tension in the rolling direction. At a position where the steepness is negative, a larger tensile force acts than at the central portion, and conversely, at a position where the steepness is positive. Is smaller than that at the center. In the conventional method of rolling using a tapered work roll, elongation of the end of the plate cannot be obtained, so that a very large tensile stress is generated, which causes breakage of the plate. According to FIG. 16, it can be seen that the difference in steepness of the steel material rolled by the method of the present invention is small, and such a deviation in tension is also small.

[0049]

Example 2 Roll cross rolling was performed under the same rolling conditions as in Example 1. A work roll having the same taper as in Example 1 and having a different surface roughness in the axial direction (0.2 μm in Ra and 1.0 μm in Ra) as shown in FIG. 14 was used. At this time, only the tapered portion increased the surface roughness. The roll cross angle (θ in FIG. 9) was set to 0.6 °, and the arrangement was such that an inward shearing force in the sheet width direction worked (the arrangement in FIG. 10).

For comparison, parallel roll rolling (cross angle 0 °) using the same rolls used in the method of the present invention was performed. In each case, the surface roughness of the roll was the same as that of the present invention.

FIG. 17 shows the thickness deviation based on the center of the plate.
FIG. 18 shows the steepness calculated from the stretching difference from the center of the plate at a certain position in the plate width direction in the same manner as in Example 1. From these figures, it can be seen that the steel material rolled by the method of the present invention has a cross-sectional shape as good as that of a steel material rolled using a conventional tapered work roll, and also has an excellent planar shape.

[0052]

According to the method of the present invention, a metal plate having a small edge drop can be manufactured without causing a shape defect. Therefore, the magnitude of the tension acting in the rolling direction of the metal sheet is also made uniform in the sheet width direction, so that no crack or break occurs during rolling.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between a work roll and a metal material during rolling. (a) is a diagram showing that when rolled using a normal roll, the surface of the work roll is deformed and an edge drop occurs at the end of the metal material, and (b) shows the use of a tapered roll. FIG.

FIG. 2 is a diagram illustrating an example of a taper roll.

FIG. 3 is a diagram showing a conventional method of rolling by combining taper rolls.

FIG. 4 is a plan view when the roll is flexed in the horizontal direction and rolled, and arrows indicate the direction of the rotation vector of the roll.

FIG. 5 is a diagram showing a relationship between a rolled material and upper and lower work rolls when rolling is performed using a spiral polishing roll. (a) is a sectional view as seen from the exit side, and (b) is a plan view as seen from above. In the drawing, F ₁ and F ₂ indicate the shearing force in the plate width direction.

FIG. 6 is an example of a combination of work rolls in which both ends of a barrel (including a portion in contact with a plate width end) are spirally polished.

FIG. 7 is an example in which rolling is performed while changing the polishing state of upper and lower work rolls.

FIG. 8 is a diagram showing a relationship between a roll and a metal material during rolling.

FIG. 9 shows a relationship between a rolled material and upper and lower work rolls in roll cross rolling. (a) is a plan view as viewed from above, and (b) is a cross-sectional view as viewed from the entry side of the rolled material. F ₁ and F ₂ in the figure indicate the shearing force in the plate width direction.

FIG. 10 shows an example in which roll cross rolling is performed by changing a friction coefficient in an axial direction, and shows a relationship between a rolled material and upper and lower work rolls. (a) is a plan view of a state in which rolls with surface roughness changed in the axial direction are arranged upside down to perform roll cross rolling, and (b) is a cross-sectional view of the rolled material as viewed from the entry side. is there.

FIG. 11 shows an example of a work roll in which the surface roughness is changed in the width direction.

FIG. 12 shows an example of a tapered roll having a spiral polishing stitch.

FIG. 13 is a diagram illustrating a taper of a work roll used in Example 1.

FIG. 14 is a diagram illustrating a taper of a work roll used in Example 2.

FIG. 15 is a diagram showing a thickness deviation in the width direction with respect to the center of the plate.

FIG. 16 is a diagram showing a steepness calculated from a stretching difference from a plate center portion at a certain position in a plate width direction.

FIG. 17 is a diagram showing a thickness deviation in the width direction with respect to the center of the plate.

FIG. 18 is a diagram showing a steepness calculated from a stretching difference from a plate center portion at a certain position in a plate width direction.

[Explanation of symbols]

1. 1. upper work roll; Lower work roll, 3.
Metal plate.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B21B 37/28 B21B 37/00 118 (72) Inventor: Masahiro Matsuura 4-33 Kitahama, Chuo-ku, Osaka City, Osaka Sumitomo Metal Inside Industrial Co., Ltd. (72) Inventor Kanji Hayashi 4-6-22 Kanon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Inside Mitsubishi Heavy Industries, Ltd. (72) Inventor Kazuo Morimoto 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Laboratory (56) References JP-A-5-50102 (JP, A (58) Fields investigated (Int.Cl. ⁶ , DB name) B21B 1/22 B21B 27/00 B21B 27/02 B21B 37/28 B21B 37/00

Claims (2)

(57) [Claims] 1. A metal plate is rolled using a work roll having a polished spiral spiral and having a tapered portion in contact with a plate width end of a rolled material. A method for producing a metal plate having a small edge drop, wherein a shear force is applied. 2. A work roll having a tapered portion in contact with a strip width end portion of a rolled material, and a friction coefficient between the work roll and the metal plate is changed in an axial direction of the work roll. A method for producing a metal sheet having a small edge drop, wherein the metal sheet is subjected to roll cross rolling and subjected to inward shearing force in the sheet width direction to perform rolling.