JP2642575B2 - Welding tube forming method and forming stand - 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 continuously forming and welding a metal band having a predetermined width by electric resistance welding or another welding method. The present invention relates to a forming method for forming a good welded pipe and a forming stand.

[0002]

2. Description of the Related Art Generally, in a manufacturing process for manufacturing a welded pipe such as an electric resistance welded steel pipe, a metal band having a predetermined width is formed by a metal strip.
It is continuously supplied to a forming roll group consisting of a plurality of breakdown rolls, side rolls, fin pass rolls, and the like, and then manufactured by performing welding such as high frequency welding with a squeeze roll.

[0003] Since this method can be manufactured continuously, high efficiency and low cost are great advantages. For this reason, it is widely used for pipes for mechanical structures, boiler pipes, oil well pipes, various pipes, and the like, and recently, demands for thin-walled pipes, thick-walled pipes, high-tensile pipes, and the like are increasing. Further, it is strongly desired to ensure high dimensional accuracy for high-grade pipes.

However, when these thin-walled pipes, thick-walled pipes, and high-strength pipes are formed by a conventional method, a defective shape occurs. That is, as shown in FIG. 8, in the initial forming process of the edge forming, a problem such as insufficient bending of the edge portion of the material to be formed occurs in the pair of upper and lower breakdown rolls.

On the other hand, as shown in FIG. 11, during edge forming, a so-called W-bend is formed by bending the vicinity of the center of the material to be formed into a curvature opposite to that of the product and bending both ends to the same side as the product. The law has been put to practical use. The effect of this method is introduced, for example, in the Journal of the Japan Society for Technology of Plasticity, Journal of Japan Society for Technology of Plasticity, Spring Meeting, p519.

[0006] Japanese Patent Application Laid-Open No. 01-044217 discloses that a pilot hole type roll of a horizontal roll of a forming stand for edge forming is composed of two rolls,
A method is described in which the angle of inclination in the traveling direction of the metal strip can be adjusted so that the edge portion can be sufficiently formed with both thick and thin materials.

On the other hand, in the process of manufacturing such a metal pipe by roll forming and welding, the pipe diameter is reduced for the purpose of reducing the roll cost by reducing the number of hand-held rolls and improving the line operation rate by reducing the frequency of roll changeover. For such different metal strips, there is a demand for forming rolls that can be used in common with rolls. On the other hand, Japanese Patent Application Laid-Open No. 62-16 / 1987
A roll as shown in Japanese Patent No. 6027 has been devised,
Has been put to practical use.

[0008]

As described above, as described above,
In the case of a breakdown roll that performs edge forming in a conventional molding method, a problem of a defective shape occurs particularly when a thin-walled tube, a thick-walled tube, or a high-tensile tube is molded. In order to eliminate the shape defect, when the edge forming is to be strengthened by the subsequent fin pass roll, the thickness increase 15 of the edge portion as shown in FIG. Becomes

Further, in the breakdown roll of the W-bend system shown in FIG. 11, the bending force of the edge portion can be sufficiently ensured, so that the edge portion can be bent as compared with the conventional method. In the molding process from the contact start point of the molding material and the upper roll to just below the roll,
Because the upper roll and the material to be formed are in local contact, FIG.
The indentation 16 as shown in FIG. Furthermore, even in this method, it is not possible to fundamentally solve the shape defect when forming a thick-walled pipe or a thin-walled pipe that is larger or smaller than a design thickness of the upper roll to some extent, and it is not possible to solve the problem of forming thickness commonality. Has not been expanded.

On the other hand, Japanese Patent Application Laid-Open No. 01-0442 is disclosed.
In the No. 17 publication, compared with the normal edge forming method,
Since the contact between the molding material and the roll changes continuously, reduction of indentation and the like can be expected. However, in this technique, since the metal strip is formed so as to sequentially contact the fixed upper roll by inclining the lower roll, the inner diameter of the bending curvature is constant regardless of the thickness, As a result, the bending curvature outer diameter differs depending on the thickness,
There is a limit to the range of wall thickness commonality. In addition, it does not have roll sharing with the outer diameter.

On the other hand, the roll disclosed in Japanese Patent Application Laid-Open No. 62-166027 has a roll versatility in a wide range of tube outer diameters. Since it tends to be localized and has problems such as poor shape, it is not particularly suitable for forming a thick-walled pipe.

[0012]

According to a first aspect of the present invention, there is provided a method for forming a metal strip having a predetermined width by roll forming and welding in a welding pipe production line, the method comprising: By arranging a pair of upper and lower horizontal rolls divided into two in the width direction of the metal band at different positions in the metal band forming direction, bending of one end of the metal band is started and then bending of the other end. Is a method for forming a welded pipe.

The second aspect of the present invention is for maximizing the effect of the present invention. The upper roll of the pair of upper and lower forming horizontal rolls each divided into two in the width direction of the metal band. The angle α _u and the turning angle α _d of the lower roll,
The turning directions of the upper and lower rolls are reversed, and 0 < α _u ≦ 45 °, 0 < α _d ≦ 30 ° (however,
α _u : the angle between the metal band width direction axis and the roll axis of the upper horizontal roll, α _d : the angle between the metal band width direction axis and the roll axis of the lower horizontal roll). 2. A method for forming a welded pipe according to item 1.

Further, a third aspect of the present invention is a means for making the present invention effective regardless of the setting accuracy of the forming stand, and a pair of upper and lower forming horizontal rolls each divided into two in the metal band width direction. 3. The method for forming a welded pipe according to claim 2, wherein the upper roll has a turning angle set so that the entrance side of the roll stand faces the edge side of the metal band and the exit side of the roll stand faces the center side of the metal band. It is.

In a fourth aspect of the present invention, a pair of upper and lower horizontal rolls for bending an end portion of a metal band is provided in a production line and an initial forming roll group of a welded pipe for roll forming and welding a metal band having a predetermined width. Is divided into two in the width direction of the metal band, and the upper and lower rolls on both sides are arranged at different positions in the metal band forming direction, and the respective horizontal upper and lower rolls are adjusted in roll position setting with the vertical direction as a rotation axis. And a welding tube forming stand characterized in that the position can be adjusted in the plate width direction.

[0016]

According to the present invention, in a breakdown stand for the purpose of edge forming, horizontal rolls divided into two in the width direction of the metal strip and arranged on both sides of the line as upper rolls for the purpose of edge forming,
By shaping the metal strip in a state where the metal strip is swung and fixed with the vertical direction as the swiveling axis, it is possible to form a thin pipe to a thick pipe with high dimensional accuracy. This is because, as shown in FIG. 3, by rotating the horizontal roll, which is the upper roll, the horizontal roll in contact with the inner surface of the metal band immediately below the roll continuously turns at the bent portion of the metal band undergoing forming. This is because the contacting and molding process does not cause local contact in the molding process as in the conventional method. Further, as shown in FIGS. 2A to 2C, by changing the turning angle of the horizontal roll, the curvature formed by the upper roll history near immediately below the roll changes. The gap history can be configured according to the thickness of the band, and it is possible to accurately mold the thickness range from a thin material to a thick material.

Further, as shown in FIG. 2D, it is possible to change the curvature formed by the lower roll by changing the turning angle of the lower roll. Therefore, by adjusting the turning angle and the width direction position of the lower roll, there is an effect that the rolls can be shared with metal strips having different product pipe diameters.

Further, in the present invention, the upper and lower rolls are arranged at different positions in the metal band forming direction, so that the bending of one end of the metal band is started and then the bending of the other end is performed. It is characterized by the fact that it starts, especially in the case of small diameter sizes,
This solves the problem that the rolls on both sides interfere with each other when the upper and lower rolls rotate, thereby restricting the rotation angle. Therefore, the interval 20 (see FIG. 1) between the upper and lower rolls in the metal band forming direction is determined by the upper and lower roll diameters and the design turning angle range.

Generally, the turning angle of the upper roll is determined by the hole shape of the upper roll, the forming outer diameter of the metal band, the thickness of the metal band,
The turning angle of the lower roll is determined by the upper roll diameter and the like, and the turning angle of the lower roll is determined by the outer shape of the metal band, the forming outer diameter of the metal band, the lower roll diameter, and the like.
In order to maximize the effects of the present invention, the turning angle directions of the upper and lower rolls are limited as follows.

It is necessary to increase the turning angle of the upper roll as the forming thickness of the metal strip becomes thinner. However, if the turning angle is excessive, the slip between the upper roll and the metal strip becomes excessive, and forming scratches, roll seizure, Since the roll life may be shortened, the upper limit of the turning angle is set to 45 in consideration of the shared range of the metal band.
°. The lower limit is used to clarify the difference from the conventional technology.
More than 0 °.

Further, by increasing the turning angle of the lower roll, the range of common use of the forming outer diameter of the metal band is widened. However, when the turning angle is too large, the same problem as described above is caused. Will limit its scope,
The upper limit of the turning angle was set to 30 ° in consideration of the common range of the forming outer diameter of the metal strip. Lower bounds clarify differences from prior art
For this reason, it was set to more than 0 °. As a result, the outer diameter can be shared about 1.5 to 2 times.

On the other hand, when the upper and lower rolls are turned, a force may be applied to the rolls in the width direction of the metal band due to the sliding relationship between the roll and the metal band, and a run-out may occur. For example, as shown in FIG. 8 (a), the upper roll is set so that the entrance side of the roll stand faces the edge side of the metal band and the exit side faces the center side of the metal band, and the lower roll reverses its turning direction. When the upper and lower rolls cross each other by setting (in this case, since the contact point of the upper roll shifts from the innermost edge of the metal strip to the inside, the upper roll is hereinafter referred to as an inward molding die). The roll has an outward deflection in the width direction, and the lower roll has an inward deflection in the width direction. On the other hand, FIG.
As shown in the above, the upper roll is set so that the entrance side of the roll stand faces the center side of the metal band and the exit side faces the edge side of the metal band, and the lower roll sets the upper and lower rolls by setting the turning direction to the opposite direction. When they intersect (in this case, since the contact point shifts from the inside of the metal band to the edge portion of the upper roll, the upper roll is hereinafter referred to as an outward molding die), and the upper roll has an inward width direction. The run-out and the run-out in the width direction are generated on the lower roll. Here, in the case of the outward molding die, the edge portion is insufficiently bent due to the upper roll not contacting to the outermost edge. Also, as shown in FIG. Local thinning due to narrowing may occur.

On the other hand, in the inward molding die, there is no concern about the above-mentioned problems, and the run-out force of the upper and lower rolls acts in a direction advantageous for edge molding, and advantages such as reduction of the rolling force of the upper and lower rolls can be expected. . Therefore, in particular, in the case of a stand in which run-out is likely to occur due to the rigidity of the stand or the like, it is desirable to use the inward-molding die described in claim 3.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a front view and a plan view of an example of a roll to which the present invention is applied. Here, the inclination angle α _d of the lower roll 2 is determined according to the forming curvature of the edge of the metal strip 10 to be formed. The upper and lower roll width direction positions on both sides are determined according to the metal strip width and the bending length. Further, according to the thickness of the metal strip 10,
The turning angle α _u of the upper roll 1 is determined.

FIG. 2 shows an example of the history of the roll gap immediately below the roll when the turning angle is set according to the thickness and the bending curvature of the metal strip. FIG. 3 shows an example of a deformation state of the metal strip according to the history of the roll gap. FIG. 4 shows an example of a side view and a front view of an edge bend stand to which the present invention is applied. The roll support beam members 7 and 8 vertically hold the upper and lower roll bearing members 3 and 4 respectively, and the upper roll support beam member 7 has a structure that can be moved and fixed in the vertical direction by the screw down screw shaft 9. ing. The upper and lower roll supports 5, 6
The structure is such that it can be moved and fixed in the width direction by rotation of a screw shaft (not shown) installed in the beam members 7 and 8 or sliding of a slide bracket on a rail (not shown).
Further, the upper roll bearing members 3 and 4 have a structure that can be turned and fixed around a vertical axis as a shaft center by a method such as gear driving not shown.

If necessary, as shown in FIG.
In the center of the metal band 10 at the center in the plate width direction, the metal band 1
Central upper and lower rolls 11, 1 for holding the central part
It is also possible to install two. In this embodiment,
Although an example is shown in which a pair of upper and lower horizontal rolls on both sides are arranged in the same stand, they may be arranged on different stands depending on the position interval 20 on both sides. Furthermore, it is also possible to install a guide roll on the side where edge bending is not performed.

FIG. 6 shows a yield stress of 294 N / mm ² , φ50.
FIG. 4 shows a curvature distribution and a wall thickness distribution after forming a single stand when the present invention is applied and when the present invention is not applied to edge forming of a strip of 8 mm × t2 mm and 10 mm, respectively. In the conventional method, bending is insufficient with thin material,
Although a bent portion indentation is generated in a thick material, a very good shape is obtained by applying the present invention.

On the other hand, FIG. 7 shows the same material, φ34.0 × t by adjusting the turning angle using the same roll as described above.
3 shows a curvature and a thickness distribution of a strip steel equivalent to 5 mm after edge forming. The molding is carried out almost as set and the shape is good. It can be seen that by applying the present invention, the roll has the same outer diameter.

Table 1 shows the results of the curvature and the wall thickness reduction when the same roll was used to perform the forming while changing the turning angle of the upper and lower rolls for various forming outer diameters and wall thicknesses. It is. It can be seen that by applying the present invention, improvement in edge formability, reduction in wall thickness reduction, and sharing of roll outer diameter can be obtained. Further, it is understood that the effects of the present invention can be maximized by applying the second and third aspects of the present invention to the turning angle setting condition.

[0030]

[Table 1]

[0031]

As described above, according to the present invention, when a metal tube is continuously roll-formed and welded to produce a welded pipe, a breakdown roll apparatus in an initial forming process for edge forming is used. Edge bending can be carried out without impairing the wall thickness accuracy of the material to be molded, and rolls can be commonly used for forming metal strips having different pipe diameters.

[Brief description of the drawings]

FIG. 1 is a front view and a plan view of an example of a roll to which the present invention is applied.

FIG. 2 is a diagram showing an example of upper and lower roll gap histories set according to each forming curvature and wall thickness when the present invention is applied.

FIG. 3 is a view showing the progress of forming a metal band in the vicinity immediately below a roll.

FIG. 4 is a view showing an example of a molding apparatus to which the present invention is applied.

FIG. 5 is a view showing another example of a molding apparatus to which the present invention is applied.

FIG. 6 shows examples of curvature and wall thickness distribution after single stand molding when the present invention is applied and when it is not applied.

FIG. 7 is an example of a curvature and a thickness distribution after molding when the turning angle is adjusted using the same roll as in FIG. 6;

FIG. 8 (a) is an example of an inward molding die according to the present invention,
(B) is an example of the outward mold in the present invention.

FIG. 9 shows an example in which inward deflection occurs in the upper roll when the outward molding die according to the present invention is applied to the W-bend method.

FIG. 10 is a cross-sectional example of a conventional edge bend roll.

FIG. 11 is an example of a W-bend type breakdown roll.

FIG. 12 is a cross-sectional view of a metal strip showing an example of edge thickening that deteriorates dimensional accuracy.

FIG. 13 is a cross-sectional view of a metal band showing an example of a bent portion indentation that similarly deteriorates dimensional accuracy.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper roll 2 Lower roll 3 Upper roll bearing 4 Lower roll bearing 5 Upper roll support 6 Lower roll support 7 Upper roll support beam 8 Lower roll support beam member 9 Screw screw shaft 10 Metal strip (Material 11) Central upper roll 12 Central lower roll 15 Edge thickening 16 Bent portion indentation 19 Fin pass roll 20 Both sides stand distance in the forming direction

Claims (4)

(57) [Claims] 1. A method for forming a metal band having a predetermined width in a roll forming and welding process in a welding pipe production line, wherein a pair of upper and lower portions divided into two in a metal band width direction for the purpose of bending a metal band end portion. Forming the welded pipe by arranging the horizontal rolls at different positions in the metal band forming direction, thereby starting bending at one end of the metal band and then starting bending at the other end. Method. 2. The turning angle α _u of the upper roll and the turning angle α _d of the lower roll of the pair of upper and lower forming horizontal rolls divided into two in the width direction of the metal band are respectively reversed from the turning direction of the upper and lower rolls. 0 < α _u ≦ 45 ° 0 < α _d ≦ 30 ° where α _{u is the} angle between the metal band width direction axis and the roll axis of the upper horizontal roll α _d : the metal band width direction axis and horizontal lower 2. The method for forming a welded pipe according to claim 1, wherein the angle is set within a range of an angle formed by a roll axis of the roll. 3. In a pair of upper and lower forming horizontal rolls divided into two in the width direction of the metal band, the upper roll is such that the entrance side of the roll stand faces the edge side of the metal band and the exit side of the roll stand faces the center side of the metal band. The method for forming a welded pipe according to claim 2, wherein a turning angle is set in the welding pipe. 4. A pair of upper and lower horizontal rolls for bending an end portion of a metal band are divided into two in a width direction of the metal band in a production line of a welded pipe for forming and welding a metal band having a predetermined width. Further, the respective upper and lower rolls on both sides are arranged at different positions in the metal band forming direction, and the respective horizontal upper and lower rolls are adjusted in roll position setting with the vertical direction as a rotation axis, and the position in the sheet width direction. A welding tube forming stand characterized in that it can be adjusted.