JPH03230817A - Manufacturing device for welded pipe - Google Patents

Abstract

PURPOSE:To obtain a welded pipe in corresponding to a plate thickness of wide range by providing the rotary shaft of two rolls of the both side of the lower roll having an angle of inclination to the direction orthogonal to the advancing direction of the metal strip and having an angle of intersection with the direction of the width direction of the metal strip on the crossing orthogonally with the advancing surface. CONSTITUTION:The lower rolls consist of rolls more than three divided in the rotary shaft direction. Two rolls of both sides are arranged so that their rotary shafts has inclination of inclining angle alpha with the direction vertically crossing to the advancing direction of metal strip on the advancing surface of metal strip, and the rotary shafts has crossing angle beta with the width direction of metal strip on the vertically crossing surface to the advancing surface of metal strip. The contacting point of the lower roll and the metal strip 4 is, because each lower roll 5 has its inclining angle beta and its crossing angle alpha, moved following to the advancing of the metal strip bend-forming and its position is made different and so do not receive the concentrated load at its one point. Therefore, this device copes with the steel plate of wide range plate thickness from a thick wall material to a thin wall material, because of needless of the roll shifting in correspond to the plate thickness, the productive technique can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a welded pipe manufacturing apparatus incorporating a forming roll group for continuously forming a metal strip into a cylindrical shape.

(Prior Art) For example, welded pipes such as electric resistance welded pipes are manufactured by first gradually forming a flat metal band into an arc shape in a roll forming process, and after forming the arc-shaped metal band into a tube shape in the final stage. Manufactured by melt-welding the abutting edges. In this step of forming into a tubular shape, so-called roll bending is performed, and the first step is generally called breakdown, which is formed into an arc shape, and then that arc is shaped into a tubular shape with a smaller radius. The final step is called the fin pass, in which a tubular butt edge is formed.

In roll forming such welded pipes, in order to obtain the desired product shape, it is extremely important to bend both ends of the metal strip in the width direction, and if this bending is not done properly, This causes a decrease in the shape quality of the welded part or a decrease in material yield.

(Problems to be Solved by the Invention) Nowadays, along with improvements in the performance of welded pipes, the use of welded pipes is being expanded due to their ease of manufacture. Of course, welded pipes have also come to be used for pipes made of thick-walled materials with considerable plate thickness.

However, when obtaining welded pipes using thick-walled materials, it becomes difficult to form the edges as the plate thickness increases, so there are unformed parts near the edges where bending has not been performed. remain. For this reason, when welding this part, welding abutment becomes irregular and welding quality deteriorates.

FIG. 3 is a schematic side view showing a typical example. In particular, the vicinity of the welded part 1' inside the steel pipe 1 remains as an unformed straight part a, resulting in a so-called roofing phenomenon. The straight portion a, which is not bent and formed, is welded as it is to form a roof shape, which remains in the final product.

In addition, since metal strips ranging from thin to thick materials are usually formed using the same roll, for example, as shown in FIG. The edges of the thin metal strip 4 cannot be bent. On the contrary, in thin materials, the edges tend to stretch a little compared to the center of the metal strip, and these stretched edges bend and become wavy, making the weld unstable. If the material is thin, for example, the ratio t/D (a) of the wall thickness t to the outer diameter is less than 1.5%, undulations will occur at the side edges of the metal band during forming. This is so-called edge buckling. On the other hand, as shown in FIG. 4(b), if the thickness is too large, it becomes difficult to form the edge, and roofing will occur.

In this way, each roll has an optimal forming range in terms of wall thickness, so the thickness of the metal strip to be formed is limited, and the rolls are rearranged as appropriate depending on the thickness of the metal strip to be formed. Currently, it is being molded.

Furthermore, as a method for bending edges for manufacturing welded pipes, there is a W-bending method shown in Japanese Patent Publication No. 59-27654. is unavoidable. Furthermore, since it is not possible to form thin to thick materials using the same roll, the rolls are changed for each thickness range.

FIG. 5 is a schematic diagram showing the contact state between the roll and the material when edge bending is performed using a normal horizontal roll stand. Here, a lower roll 3 which is a grooved roll and a metal band 4
First, both edges (points A and B) of the metal strip 4 come into contact with each other at the roll entrance.

Then, the lower roll 3 pushes the metal band 4 at points A and B, and the metal band 4 is wound around the upper roll 2 to bend the edge of the metal band 4. Therefore, the portions of the metal strip 4 corresponding to points A and B receive a concentrated load and thinning occurs. This thinning of the edge of the metal band occurs not only in the case of the edge bend type forming shown in FIG. 5, but also in the case of forming by the W bend method.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 64-44217, there is a welded pipe manufacturing apparatus in which the lower roll is divided into two parts and the inclination angle in the direction of metal band movement can be adjusted. By the way, in the breakdown roll group of the existing production equipment for welded pipes of medium diameter or larger (outer diameter 10 inches or larger), -
For boat fishing, the roll diameter becomes larger and the cost of the roll increases, so the same lower roll is commonly used even if the outer diameter size, that is, the width of the metal strip is different. However, the above-mentioned Japanese Patent Application Laid-Open No. 64-44217
When applying the device shown in the publication, it is necessary to have multiple rolls in order to correspond to the outer diameter and size of the final product, and the cost of the rolls increases significantly, so it is rarely implemented in reality. I can't.

Therefore, an object of the present invention is to sufficiently bend both edges of a metal strip during roll forming of welded pipes, so that even thick materials can be prevented from thinning at the edges during edge bending. A roll that can form without causing roofing, can also form thin materials without causing edge buckling, and can perform sufficient edge bending of both thin and thick materials with the same roll. To provide a welded pipe manufacturing device incorporating a forming device, which has a low roll cost even when the roll forming device has a medium diameter or more (outer diameter 10 inches or more).

(Means for Solving the Problems) In order to achieve the above object, the present inventor completed the present invention as a result of intensive research.

Here, the gist of the present invention is to provide a method comprising: a group of forming rolls for continuously forming a metal strip into a cylindrical shape; and a welding means for joining the seams of the cylindrical metal strip formed by the group of forming rolls. In the welded pipe manufacturing apparatus, the forming roll of at least one stand of the breakdown stand of the forming roll group, the lower roll of the horizontal roll is (i) composed of three or more rolls divided in the rotational axis direction, of which At least the two rolls on both sides are configured such that: (11) in the plane of movement of the metal band, a direction perpendicular to the direction of movement of the metal band and the rotational axis form an inclination angle, and (iii) the axis of rotation is orthogonal to the plane of movement of the metal band. In a plane,
The welded pipe manufacturing apparatus is characterized in that the metal band is arranged so that the width direction of the metal band and the rotation axis form an intersecting angle.

In the present invention, the "angle of inclination" refers to the angle of inclination formed by the direction perpendicular to the direction of movement of the metal band and the rotation axis of each of the rolls on both sides of the rolls divided in the direction of the rotation axis, on the plane of movement of the metal band. In the present invention, the term "intersection angle" refers to an angle in a plane perpendicular to the plane of movement of the metal strip
This refers to the angle between the width direction of the metal strip and the rotation axis.

(effect) Hereinafter, the structure and operation of the present invention will be explained in detail.

In the present invention, the configuration in which the lower roll of "at least one stand of the breakdown stand" is composed of three or more rolls divided in the direction of its rotational axis means that in the process of forming a flat metal strip in the breakdown stand, , one stand of the roll group that is mainly in charge of edge bending always has three or more lower rolls, and if necessary, three or more lower rolls can be used in multiple stands such as 2nd and 3rd stands. This means that you may use the following rolls.

The concentrated load on the metal band edge during forming in the breakdown stand is greatest at the first stand, decreases downstream from the second and third stands, and almost disappears at the fourth stand. Therefore, it is highly effective to use three or more rolls for the lower roll of the first stand.

It is also possible to reduce the amount of molding in the first stand and increase the amount of molding in the second stand by the reduced amount.In such a case, the second stand can also use a system with three or more lower rolls. It is preferable to do so.

As described above, according to the present invention, in the roll forming apparatus for welded pipes, the lower roll is moved to a (The roll is divided into three or more rolls, at least two of which have the above-mentioned inclination angle and crossing angle, and these angles are adjustable.

In the present invention, although not limited to a specific value, the inclination angle or crossing angle of the lower roll in the metal band advancing direction is large when the material is thin, and conversely small when the material is thick. It is preferable to adjust.

Next, the reason why there are three or more lower rolls will be explained. Second
The figure schematically shows the arrangement of large-diameter and small-diameter rolls within the range that can be manufactured using the same device.

When there are two lower rolls (when there is no lower roll 6), if the lower roll 5 is shared with the roll for the small diameter size in the case of a large diameter size, the material escapes downward and cannot be formed.

Therefore, in order to share the lower roll, it is necessary to divide the lower roll into three or more parts and hold the material with the lower roll 6. Further, the lower roll 6 may be further divided into several rolls.

Next, the present invention will be explained in more detail with reference to the drawings.

)-0 Figures 1(a), 1(b) and 1(c) are a schematic cross-sectional view, a schematic side view and a schematic top view, respectively, of the roll arrangement of the device according to the invention.

As can be seen from FIGS. 1(a) and (C), in at least one horizontal stand which is mainly responsible for edge bending, the lower roll is composed of three or more rolls 5.5.
6, of which two rolls 5.5 on both sides have an inclination β ((lJt oblique angle) with respect to the feeding direction of the metal strip 4,
In addition, in FIG. 1(a), it has an inclination α (intersection angle) with respect to the width direction of the metal band in a plane perpendicular to the feeding direction of the metal band 4.

A cross section perpendicular to the feeding direction when the metal strip 4 is fed to this stand is also shown in FIG. 1(b).

In the figure, the cross section ■ is the cross section of the metal strip 4 when the fed metal strip 4 contacts the upper roll 2 and one of the lower rolls 5, and the cross section ■ is the cross section of the metal strip at the center position of the upper roll 2. This is the cross section at the time point when the edge bending of step 4 is completed. Moreover, the ``cross-section'' is a cross-section at an intermediate position between the ``cross-section'' and the ``cross-section''. As is clear from FIGS. 1(B) and 1(C), the contact point between the lower rolls 5 and the metal strip 4 is such that each lower roll 5 has an inclination angle β and an intersecting angle α. Therefore, as the bending process of the metal band 4 progresses, it moves and its position changes, and the - point does not receive a concentrated load. Therefore, thinning of the edge of the metal band 4 does not occur, and forming can be carried out sufficiently up to the edge of the metal band, so that roofing does not occur.

Next, in the case of metal strips with different wall thicknesses, the lower roll adjustment of the upper roll 2 and the inclination angle β or/and crossing angle α of the lower roll 5.5 are performed.
By adjusting the thickness of the thin material to be large, it is possible to arrange the rolls so that the edges of the metal strip 4 can be sufficiently formed.

Particularly in the case of thin materials, bending the edges increases the rigidity of the edges, which is highly effective in preventing edge buckling.

In this way, according to the present invention, by adjusting the inclination angle β and/or the crossing angle α depending on the plate thickness each time,
The same roll can sufficiently bend the edges of thin to thick materials, effectively preventing edge buckling when forming thin materials and roofing when forming thick materials. I can do it.

Note that the relationship between the plate thickness, inclination angle, and intersecting angle at this time cannot necessarily be unambiguously stated because it is also related to the radius of curvature of the lower roll, but those skilled in the art will be able to understand the relationship between the thickness and the inclination angle and the intersection angle. You can also set it as appropriate.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Using a single stand, two types of steel plates with wall thicknesses of 10+ nm and 0.7 mm were roll-formed using the welded pipe manufacturing apparatus according to the conventional example and the example of the present invention, respectively.
The moldability was compared.

FIG. 6 is a schematic explanatory diagram showing the roll shape of the conventional example at this time, and the radius of curvature R of the upper roll was 20II1 m. On the other hand, the R of the lower roll was 30 mm.

On the other hand, in the case of the present invention, as shown in the same schematic explanatory diagram in FIG. did.

FIG. 8 graphically shows the wall thickness distribution of the edge after passing through a single stand when a steel plate having a wall thickness of 10IIll11 is formed. It can be seen that when forming was performed using the roll of the conventional example, edge thickness reduction occurred by 2111ff1, but when forming was performed using the roll of the example of the present invention, almost no edge thickness reduction occurred.

Next, the curvature of the inner surface of the molded product after single stand molding is
This is shown in Figure (a) and Figure 9 (b). In the conventional example, in the case of a thick steel plate, that is, a steel plate with a wall thickness of 1OIllII+, the inner surface is not bent due to edge thinning. Furthermore, even with a steel plate having a wall thickness of 0.7 mm, it was not possible to bend the edges.

On the other hand, in the example of the present invention, it was possible to sufficiently bend to the edge in both cases, whether the thickness was 10 mm (A in the figure) or the thickness was 0.7 m+a (B, C' in the figure).

In addition, in the figure, the inner surface curvature (1/R) of 0.05 is a value when R=20+em of the upper roll. In addition, the 9th
In the example of the present invention whose results are shown in Figure (b), A,
For B and C, (inclination angle and intersection angle are respectively, (20°, 30°), (30', 30"), (2
0°, 35°).

As described above, according to the present invention, it is possible to stably manufacture welded pipes for thick-walled materials without causing edge thinning or roofing, and for thin-walled materials without causing edge buckling. Ta.

Here, the example of the present invention was incorporated into the first stage roll stand of a roll forming device of a normal electric resistance welded pipe manufacturing device, and the outer diameter was 50 mm.
．． A welded pipe with a thickness of 8 mm and a wall thickness of 10111111 or 0°71 was manufactured. Welding was performed by electric resistance welding.

As a result, in the case of a steel plate with a wall thickness of 10III11, no roofing was observed because edge wall thinning did not occur.

Further, in the case of a steel plate with a thickness of 0.7 mm, edge buckling occurred in the conventional example, but no edge buckling was observed in the example of the present invention because the edges were sufficiently bent.

The effects of the present invention are clear from the results of the above examples. That's it.

(Effects of the Invention) As described in detail above, according to the present invention, both edges can be sufficiently formed regardless of whether the material is thick or thin.
In particular, roofing of thick-walled materials, which has been a problem in the past, can be effectively prevented, and edge buckling of thin-walled materials can also be prevented, which is of great significance in terms of quality control.

In addition, by appropriately adjusting the inclination angle and crossing angle of each lower roll, it is possible to handle steel plates with a wide range of thicknesses from thick to thin.
Since it is not necessary to rearrange the rolls according to the thickness of the sheet, there are great benefits in terms of production technology.

The significance of the present invention having such effects is extremely significant.

[Brief explanation of drawings]

1(a), 1(c) and 1(c) are a schematic sectional view, a schematic side view, and a schematic side view, respectively, illustrating the arrangement of upper and lower rolls of a forming device of a welded pipe manufacturing apparatus according to the present invention. Top view; Figure 1 (c) is a schematic sectional view showing the ■ cross section, ■ cross section, and ■ cross section in Figure 1 (c) and Figure 1 (C): Figure 2 (a) and Figure 2 ( b) is a schematic cross-sectional view and a schematic top view showing the welded pipe manufacturing apparatus according to the present invention, respectively, used to show the reason why the lower roll is divided into three parts; Fig. 3 is a welding according to the conventional example. A schematic cross-sectional view showing the roofing, which is a defect in the pipe: Figures 4(a) and 4(a) are schematic explanatory views showing the roll-caught state of thin-walled material and thick-walled material, respectively; Schematic diagrams 6 and 7 of the contact state between the molding material and the molded material
The figure is a schematic explanatory diagram showing a conventional example roll and a roll according to an example of the present invention, respectively, which were used in an example of the present invention; and Figs. It is a graph summarizing the results of an example. 1: Welded steel pipe 2: Upper roll 3: Lower roll
4: Metal band 5.6: Split lower roll

Claims (1)

[Scope of Claims] A welded pipe manufacturing apparatus comprising a forming roll group that continuously forms a metal strip into a cylindrical shape, and a welding means for joining the joints of the cylindrical metal band formed by the forming roll group. In the forming roll of at least one stand of the breakdown stand of the forming roll group, the lower roll of the horizontal roll is (i) composed of three or more rolls divided in the rotational axis direction, of which at least two on both sides are (ii) in the plane of movement of the metal band, a direction perpendicular to the direction of movement of the metal band and the rotational axis form an inclination angle, and (iii) in a plane perpendicular to the plane of movement of the metal band, A welded pipe manufacturing apparatus characterized in that the width direction of the welded pipe is arranged such that the rotation axis and the rotation axis form an intersecting angle.