JPH072252B2 - Welded pipe manufacturing equipment - Google Patents

Description

Description: TECHNICAL FIELD 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, in a welded pipe such as an electric resistance welded pipe, first, a flat metal strip is gradually formed into an arc shape in a roll forming step, and the arc-shaped metal strip is formed into a tubular shape in a final stage, Manufactured by melt welding the butt edges. At this stage of forming into a tubular shape, so-called roll bending is performed, and as a first step, forming into an arc shape generally called breakdown is performed, and then the arc is formed into a tubular shape with a smaller radius. Finally, the tubular butt edges are formed in a step called fin pass.

In the roll forming of such a welded pipe, in order to obtain a desired product shape, it is extremely important to perform bending forming on both ends of the metal strip in the width direction, and when this bending forming is not performed properly. In addition, it causes deterioration of the shape quality of the welded part or reduction of material yield.

(Problems to be solved by the invention) By the way, today, together with the performance improvement of the welded pipe, the use of the welded pipe is expanded because it is easy to manufacture. Of course, a welded pipe has come to be used also in a pipe made of a thick material having a considerable plate thickness.

However, when a welded pipe is obtained by using a thick material, it is difficult to form the edge portion as the plate thickness increases.Therefore, there is an unformed portion that is not bent and formed near the edge portion. Remain. For this reason, if welding is performed on the relevant portion, the welding abutment is imperfect and the welding quality is deteriorated.

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

Further, since a metal strip having the same width from thin-walled material to thick-walled material is usually formed on the same roll, as shown in FIG. 4 (a), for example, a mesh is formed between the upper roll 2 and the lower roll 3. The inserted thin metal strip 4 cannot be bent at the edge. Rather, in the thin-walled material, the edge tends to extend to some extent as compared with the central portion of the metal band, and this extended edge bends and becomes wavy, which makes the welded part unstable. Thin material,
For example, when the ratio t / D (%) between the wall thickness t and the outer diameter D is 1.5% or less, corrugation occurs at the side edge portion of the metal strip during molding. This is so-called edge buckling. On the other hand, FIG. 4 (b)
As shown in (1), if the wall thickness is too thick, it becomes difficult to form the edge, and then roofing occurs.

In this way, since each roll has an optimum forming range from the viewpoint of the wall thickness, the wall thickness of the metal strip to be formed is limited, and the rolls are appropriately rearranged according to the thickness of the metal strip to be formed. The current situation is to perform roll forming.

Further, as a method for bending an edge for manufacturing a welded pipe, there is a W bend method disclosed in Japanese Patent Publication No. 59-27654. However, this W bend method also reduces the thickness of the edge that occurs during the edge bending. Is inevitable. Further, since it is not possible to form a thin material having the same width to a thick material with the same roll, rolls are changed for each range of a certain thickness.

FIG. 5 is a schematic explanatory view showing a contact state between a roll and a material when an edge is bent and formed by a horizontal roll which is an ordinary breakdown stand. Here, the lower roll 3 which is a hole-shaped roll and the metal strip 4 come into contact with each other at both edges (points A and B) of the metal strip 4 at the roll entrance. Then, the lower roll 3 pushes the metal strip 4 at points A and B, winds the metal strip 4 around the upper roll 2, and bends the edge of the metal strip 4. For this reason, the portion corresponding to the points A and B of the metal strip 4 receives the concentrated load, and the wall thickness is reduced. This metal band edge thinning is not limited to the case of the edge bend type molding shown in FIG. 5 and is the same in the case of the W bent method.

Further, as disclosed in Japanese Patent Laid-Open No. 64-44217, there is an apparatus for manufacturing a welded pipe in which a lower roll is divided into two parts and an inclination angle in a metal band advancing direction can be adjusted. By the way, in the existing break-down rolls of welded pipe manufacturing equipment of medium diameter or more (outer diameter of 10 inches or more), the roll diameter is generally large and the roll cost is high. Even if the size, that is, the metal band width differs within a predetermined range, the lower roll uses the same roll in common, only by replacing the upper roll with one having different arc curvatures and body lengths at both ends. However, when applying the device shown in the above-mentioned Japanese Patent Laid-Open No. 64-44217 to such a device, it is necessary to have a plurality of rolls in order to correspond to the outer diameter size of the final product, etc. However, it cannot be implemented in reality.

Therefore, the purpose of the present invention is, in the roll forming of the welded pipe, by sufficiently performing the bend forming of both edges of the metal strip, even in a thick material, edge thinning does not occur during edge bend forming, that is, Molding can be performed without causing roofing, while thin-walled materials can be molded without causing edge buckling, and moreover, edge bending can be performed from thin-walled materials to thick-walled materials with the same lower roll. A welded pipe manufacturing device incorporating a roll forming device. Even in a roll forming device with a medium diameter or more (outer diameter 10 inches or more), the number of lower rolls can be reduced and the cost of the welded pipe is low. It is to provide a manufacturing apparatus.

Further, an object of the present invention is to provide a welded pipe manufacturing apparatus provided with a roll forming device capable of effectively forming a large-diameter size to a small-diameter size, that is, a wide metal band to a narrow metal band with a shared roll. is there.

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

Here, the gist of the present invention comprises a forming roll group for continuously forming a metal strip into a cylindrical shape, and welding means for joining a joint of the cylindrical metal strip formed by the forming roll group. In the welding pipe manufacturing apparatus, the lower roll of the horizontal roll of the forming roll of at least one stand of the breakdown stand of the forming roll group is composed of three or more rolls divided in the rotation axis direction, and the lower roll is formed. Is arranged in such a manner that (i) in the traveling surface of the metal strip, the rotation axis and the direction orthogonal to the traveling direction of the metal strip form an inclination angle, and (ii) in the plane orthogonal to the traveling surface of the metal strip. , The width direction of the metal strip and the rotation axis are arranged so as to form an intersecting angle, and (iii) one or both of the inclination angle and the intersecting angle are attached so as to be adjustable according to the thickness of the metal strip. From An apparatus for manufacturing a welded pipe, characterized in that the roll comprises at least two sides of the rolls.

In the present invention, the “inclination angle” means, on the advancing surface of the metal strip, each of the lower rolls divided into three or more in the direction orthogonal to the traveling direction of the metal strip and the rotation axis direction. In the present invention, the "crossing angle" refers to the angle formed by the width direction of the metal strip and the rotation axis in the plane orthogonal to the advancing surface of the metal strip.

(Operation) Hereinafter, the configuration and operation of the present invention will be described in detail.

In the present invention, the configuration that the lower roll of "at least one stand of the breakdown stand" is composed of three or more rolls divided in the rotation axis direction means that a flat metal strip is formed in the breakdown stand. , One of the rolls mainly in charge of edge bending is always composed of three or more lower rolls. If necessary, two stands, three stands and three or more stands also have three lower rolls. This means that the above rolls may be used.

The concentrated load at the time of forming on the edge of the metal strip in the breakdown stand is the largest in the first stand, decreases toward the second stand and the third stand toward the downstream, and almost disappears in the fourth stand. Therefore, if the lower roll of the first stand is made up of three or more rolls, the effect is great.
It is also possible to reduce the amount of forming on the first stand and increase the amount of forming on the second stand by the reduced amount. In such a case, the lower roll of the second stand also has three or more roll systems. Preferably.

As described above, according to the present invention, in the roll forming apparatus for a welded pipe, in at least one horizontal roll stand that is mainly in charge of bending and forming the edge in the initial stage of the roll forming process, the lower roll is The roll is divided into two or more, of which at least two rolls on both sides have the above-described inclination angle and crossing angle, and these angles are adjustable.

In the present invention, the mechanism itself for changing and adjusting the tilt angle and / or the crossing angle of the divided lower rolls may have any structure. For example, a U-shaped bearing member that pivotally supports the rolls may be used. It may be supported and slid on the cylindrical seat surface within the valve seat.

That is, when it is desired to change only one of the inclination angle and the crossing angle, it is necessary to slide within the cylindrical seat surface so that the roll axis is in the direction to be changed by the desired angle. Good. Alternatively, a cradle may be provided and the shaft center may be appropriately rotated by a hydraulic device.

If the tilt angle and the crossing angle can be changed at the same time, the roll holding seat should be supported by a cylindrical seating surface whose arc surface is 90 ° in phase from the initial position. The bearing member of the roll, which is tilted in a direction 90 ° in phase with the tilting direction of the member or is fixedly supported by the cradle, is supported on the cylindrical seat surface in the roll valve seat with respect to the cradle, You may make it slide.

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

Next, the reason why there are three or more lower rolls will be described. Second
The figure schematically shows the roll arrangement in the case of molding a large diameter size and a small diameter size within the manufacturable range of the same device, the left half is a case of molding a small diameter size with an upper roll with a small arc curvature of the end, The right half shows the case of forming a large diameter size with an upper roll having a large arc curvature at the end.

As can be seen from FIG. 2, when there are two lower rolls (there is no lower roll 6 in the figure), if the lower rolls 5 on both sides in the large diameter size are shared with the rolls in the small diameter size, the lower rolls on both sides The interval between 5 and 5 becomes large, and the central portion in the width direction of the metal strip, which is the raw material, escapes downward, and molding cannot be performed.

Therefore, in order to share the lower roll, the lower roll is divided into three or more, and the lower roll 6 is divided into the lower rolls 5 and 5 on both sides.
It is necessary to position the metal strip as a raw material so that the central portion of the metal strip in the width direction does not escape downward. The lower roll 6 may be further divided into several rolls.

Next, the present invention will be described more specifically with reference to the drawings.

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

As can be seen from FIGS. 1 (a) and 1 (c), in at least one horizontal stand mainly responsible for edge bending, the lower roll has three or more rolls 5, 5,
6, the two rolls 5 and 5 on both sides have an inclination β (inclination angle) with respect to the feeding direction of the metal strip 4, and
In FIG. 1 (a), there is an inclination α (crossing angle) with respect to the width direction of the metal strip 4 in a plane perpendicular to the feeding direction of the metal strip 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 (d). 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 at the center position of the upper roll 2. It is a cross section at the time when the edge bending is completed. The cross section is a cross section at an intermediate position between the cross sections. First
As is clear from FIG. 1B and FIG. 1C, the contact points between the lower rolls 5 and the metal strips 4 are metal strips because each lower roll 5 has the inclination angle β and the crossing angle α. As the bending forming of No. 4 progresses, it moves, its position is different, and concentrated load is not received at one point. Therefore, edge thinning of the metal strip 4 does not occur, molding can be sufficiently performed up to the edge of the metal strip, and roofing does not occur.

Next, in the case of metal strips having the same width and different thicknesses, the upper roll 2
By adjusting the rolling reduction and the inclination angle β or / and the crossing angle α of the lower rolls 5 and 5 to be larger as the thickness of the thin-walled material is increased, the roll can be arranged so that the edge of the metal strip 4 can be sufficiently formed. . Especially for thin materials,
The bending of the edge increases the rigidity of the edge portion, which is very effective in preventing edge buckling.

FIG. 10 is a schematic explanatory view of a mechanism for changing the inclination angle β or / and the crossing angle α of the lower rolls 5, 5 according to the present invention. In the illustrated example, the spherical seat 9 is used to adjust the roll inclination angle. FIG. 10 is a top view in the case of a device that does this, and is a front view in the case of a device that adjusts the roll crossing angle.

As described above, according to the present invention, by adjusting the inclination angle β or / and the crossing angle α each time according to the plate thickness,
With the same lower roll, it is possible to sufficiently bend and form edges from thin-walled materials having a width within a predetermined range to thick-walled metal strips, and it is possible to generate edge buckling during thin-walled material molding and thick-walled material molding. It is possible to effectively prevent the occurrence of roofing.

Note that the relationship between the plate thickness, the inclination angle, and the crossing angle at this time cannot always be uniquely described because it is also related to the radius of curvature of the lower roll, but those skilled in the art will describe the examples described below. Can be set appropriately from.

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

Using a single stand, two types of steel plates having thicknesses of 10 mm and 0.7 mm were roll-formed using the welded pipe manufacturing apparatuses according to the conventional example and the present invention example, and the formability was compared.

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

On the other hand, in the case of the example of the present invention, as shown in the schematic explanatory view of FIG. 7, the lower roll is divided into three parts, and the inclination angle β is set to 30 ° and the crossing angle α is set to 20 °. did.

FIG. 8 is a graph showing the wall thickness distribution of the edge after passing a single stand in the case of forming a steel plate having a wall thickness of 10 mm. It can be seen that when the roll of the conventional example was used for molding, edge thinning was 2 mm, but when the roll of the present invention was used for molding, edge thinning was hardly generated.

Next, the curvature of the inner surface of the molded product after single stand molding is set to 9
It is shown in FIG. 9 (a) and FIG. 9 (b). In the conventional example, in the case of a thick wall, that is, a steel plate having a wall thickness of 10 mm, the inner surface is not bent due to edge thinning. Furthermore, even a 0.7 mm thick steel plate could not be bent at the edge.

On the other hand, in the example of the present invention, the edge could be bent sufficiently even in the case of the wall thickness of 10 mm (A in the figure) or the wall thickness of 0.7 mm (B and C in the figure). In addition, in the figure, the inner surface curvature (1 / R) of 0.05 is a value when R = 20 mm of the upper roll. In the embodiment of the present invention, the results of which are shown in FIG. 9 (b), for A, B and C, (the tilt angle and the crossing angle are (20 °, 30 °) and (30 °, 30 ° respectively). ),
It was changed to (20 °, 35 °).

As described above, according to the present invention, it is possible to stably manufacture a welded pipe for a thick-walled material without causing edge thinning and roofing, and for a thin-walled material without causing edge buckling. It was

Here, the present invention example was incorporated into a roll stand of the first stage of a roll forming apparatus of an ordinary electric resistance welded pipe manufacturing apparatus to obtain an outer diameter of 50.8 mm.
Welded pipes having a thickness of 10 mm or a wall thickness of 10 mm or 0.7 mm were manufactured. Welding was performed by the electric resistance welding method.

As a result, in the case of a steel plate with a wall thickness of 10 mm, no roofing was observed because edge thinning did not occur. Further, in the case of a 0.7 mm thick steel plate, edge buckling was generated in the conventional example, but in the example of the present invention, the edge buckling was not seen because the edge was bent sufficiently.

The effects of the present invention are clear from the results of the above examples.

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

Further, by appropriately adjusting the inclination angle and the crossing angle of each lower roll, it is possible to cope with a wide range of plate thicknesses from thick-walled materials to thin-walled materials.
Since it is not necessary to change the rolls according to the plate thickness, the production technology has a great advantage.

Further, the present invention is economically advantageous in that the same lower roll can be shared when forming small-diameter size and large-diameter size metal strips.

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

[Brief description of drawings]

1 (a), 1 (b) and (c) are schematic sectional views, schematic side views and schematic top views, respectively, for explaining the arrangement of the upper and lower rolls of the forming apparatus of the welded pipe manufacturing apparatus according to the present invention. FIG. 1 (d) is a schematic cross-sectional view showing the cross section, cross section and cross section in FIG. 1 (b) and FIG. 1 (c); FIG. 2 (a) and FIG. 2 (b), bottom. FIG. 3 is a schematic cross-sectional view and a schematic top view, respectively, showing a welded pipe manufacturing apparatus according to the present invention, which is used for showing the reason why the side rolls are divided into three parts; FIG. 3 is a defect of the welded pipe according to the conventional example. Schematic cross-sectional views showing the roofing; FIGS. 4 (a) and 4 (b) are thin-walled materials,
FIG. 5 is a schematic explanatory view showing a rolled-in state of a thick material; FIG. 5 is a schematic explanatory view of a contact state between a roll and a molding material; FIGS. 6 and 7 are used in the embodiment of the present invention. Schematic explanatory views respectively showing a roll of a conventional example and a roll of the present invention; Figs. 8, 9 (a) and 9 (b) are graphs collectively showing the results of Examples; and Fig. 10 FIG. 4 is a schematic explanatory view of a roll crossing angle and / or tilt angle adjusting mechanism in the present invention. 1: Welded steel pipe, 2: Upper roll 3: Lower roll, 4: Metal strip 5,6: Split lower roll

Claims (1)

[Claims] 1. A welding pipe manufacturing apparatus comprising: a forming roll group for continuously forming a metal strip into a cylindrical shape; and a welding means for joining a seam of the cylindrical metal strip formed by the forming roll group. The lower roll of the horizontal roll of the forming roll of at least one stand of the breakdown stand of the forming roll group is composed of three or more rolls divided in the rotational axis direction, and the lower roll is (i) a metal strip. On the traveling surface of, the direction perpendicular to the traveling direction of the metal strip and the rotation axis are arranged so as to form an inclination angle, and (i
i) on a plane orthogonal to the traveling surface of the metal strip, the width direction of the metal strip and the rotation axis are arranged so as to form an intersection angle,
And (iii) at least one of the inclination angle and the intersecting angle, or both of which are provided so as to be adjustable according to the thickness of the metal strip, on at least both sides of the roll, the apparatus for manufacturing a welded pipe. .