JPH02197329A - Manufacturing equipment for welded pipe - Google Patents

Abstract

PURPOSE:To sufficiently execute bending of an end part extending from a thin wall material to a thick wall material by diving the lower roll of a forming roll for forming a metallic hoop to a cylindrical shape, inclining rotation axes in the metallic hoop advance direction, respectively, and also, installing the divided rolls so as to be freely movable. CONSTITUTION:A metallic hoop is formed continuously to a cylindrical shape by a forming roll group, and by welding and joining joints of this cylindrical metallic hoop, a welded pipe is obtained. In a manufacturing equipment for said welded pipe, a forming roll of at least one stand of breakdown stands of said forming roll group is constituted of a horizontal roll consisting of the upper roll 2 and the lower roll 3. Also, its lower roll 3 is constituted of two divided rolls 5, 5'. These divided rolls 5, 5' incline its rotation axes in the metallic hoop advance direction, and also, installed so as to be freely movable in the metallic hoop advance direction and/or in the axial direction of the upper roll 2. In such a way, in accordance with plate thickness, a contact point of the roll and the metallic hoop is varied continuously, bending is executed enough to the end part of the metallic hoop, and the generation of edge buckling, roofing, etc., can be prevented.

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 made by first forming a flat metal strip into an arc shape in a roll forming process, and after forming it into a tube shape in the final stage, the butt edges are melt-welded. Manufactured by In this step of forming into a tubular shape, so-called roll bending is performed, and the first step is forming into an arc shape, which is generally called breakdown, and then that arc is further formed into a tubular shape with a smaller radius. The final step is called the fin pass, in which a tubular butting edge is formed.

In order to obtain the desired product shape in roll forming of such welded pipes, bending at both ends of the metal strip in the width direction is extremely important.If this bending is not done properly, welding This may cause a decrease in the shape quality of the part or a decrease in material yield.

By the way, today, welded pipes are being used more and more because they are easy to manufacture and have improved performance, and welded pipes are used not only for pipes made of thin-walled materials, but also for pipes made of thick-walled materials with considerable plate thickness. Welded pipes have also come to be used for pipes.

(Problem to be solved by the invention) However, in the case of welded pipes made of such thick-walled materials, as the plate thickness increases, it becomes difficult to form the joints at both ends in the width direction of the metal strip, and bending becomes difficult. An unformed portion remains where no molding is performed. Therefore, in the welding process following this forming process, welding abutment becomes irregular, resulting in a significant deterioration in welding quality.

FIG. 6 is a schematic cross-sectional view showing a typical example in which a steel plate is used as the metal strip. In FIG. 6, in particular, the vicinity of the welded portion 1'' inside the steel pipe 1 remains as an unformed straight portion a, resulting in a so-called roofing phenomenon. This roofing phenomenon is a phenomenon in which straight portions that have not been bent are welded as they are and remain in the welded pipe product in the form of a roof.

In addition, since metal strips ranging from thin to thick materials are usually formed using the same roll, for example, thin metal strips caught between the upper roll 2 and the lower roll 3, as shown in Fig. 7 (Ta). The ends of the metal strip 4 are not sufficiently bent. On the contrary, when such a thin material is formed, its edges tend to stretch somewhat compared to the center, and these stretched edges bend and become wavy, making the welded part unstable. For example, if the ratio t/D of the wall thickness t to the outer diameter is less than 1.5%, undulations will occur at both ends of the metal band during forming. This is the so-called edge bank ring. On the other hand, Fig. 7 (
As shown in b), in the case of thick inner materials, it becomes difficult to form the ends, and roofing occurs.

In other words, each roll has an optimal forming range, so the current situation is to limit the thickness of the metal strip to be formed, and to change the roll to the most suitable roll according to the thickness of the metal strip to perform rolling forming. .

For example, as a method for bending both ends of a steel plate for welded pipes, W as disclosed in Japanese Patent Publication No. 59-27654 is used.
There is a bending method, but even with this W bending method, a decrease in the plate thickness that occurs during bending of both ends cannot be avoided. In addition, since it is not possible to form thin to thick materials using the same roll, the rolls are changed to the optimal roll according to the thickness of the sheet.

In this way, the conventional known method prevents a decrease in the plate thickness at both ends during forming of thick-walled materials and so-called roofing after welding, and eliminates edge buckling and welding when forming thin-walled materials. Until now, there has been no means that can completely prevent misalignment.

Herein, an object of the present invention is to provide roll forming of welded pipes.
Both ends of the metal strip in the width direction are completely bent, and even when forming thick-walled materials, there is no reduction in plate thickness when bending the ends, that is, there is no roofing, and it is possible to form thin-walled materials without causing roofing. To provide a roll forming device capable of forming without causing edge buckling in forming, and capable of sufficiently bending the end of a metal strip with the same roll for thin to thick materials. The purpose of the present invention is to provide a welded pipe manufacturing device.

(Means for Solving the Problems) In order to solve the above problems, the present inventors first used a steel plate as a metal strip and studied in detail the contact state between the roll and the steel plate during bending of this steel plate.

Contact between the roll and the material when bending the edge of a steel plate using a normal horizontal roll stand The state is schematically shown. In FIG. 8 (al), the contact between the lower roll 3, which is a grooved roll, and the metal strip 4 first occurs at both ends (point ASB) of the metal strip 4 at the roll entrance.
Figure (G))), and the lower roll 3 is at points A and B,
In Fig. 8 (C1), the metal band 4 is wrapped around the upper roll 2, and the edges of the metal band 4 are bent (
It can be seen that FIG. 8(d)). Therefore, it is considered that the portions of the metal strip 4 corresponding to points A and B receive a concentrated load, causing a decrease in the plate thickness. Therefore, it is considered that the decrease in the plate thickness at both ends of the metal strip is not limited to forming by the edge bend method shown in FIG. 8 (al), but is similar when forming by the W bend method.

In other words, the inventor of the present invention believes that the cause of the decrease in thickness that occurs when forming both ends of a thick material is that a concentrated load is applied to the metal strip due to contact with the rolls, and that in order to prevent such decrease in thickness, It has been found that it is effective to reduce the concentrated load by continuously changing the contact point between the roll and the metal strip.

In addition, when forming thick to thin materials using the same roll, it is not possible to simply change the distance between the rolls (gear gear) as in the conventional method. For cases where this is not possible, we discovered that it is effective to adjust and change the distance between the upper and lower rolls at both ends and the center of the metal strip depending on the thickness of the metal strip. Completed the invention.

The gist of the present invention is to include a forming roll group for continuously forming 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 welded pipe manufacturing apparatus, the forming rolls of at least one stand of the breakdown stand of the forming roll group include: (1) the lower roll of the horizontal roll is composed of two rolls; (iii) The welded pipe manufacturing apparatus is characterized in that the welded pipe manufacturing apparatus is installed so as to be movable in the traveling direction of the metal strip and/or in the axial direction of the upper roll.

Here, "the forming rolls of at least one stand of the breakdown stand consist of two rolls, the roll below the horizontal roll" means that when a flat metal strip is bent and formed on the breakdown stand, One of the roll groups that mainly performs bending of both ends of the roll always has two lower rolls, and if necessary,
This means that two rolls may be used as the lower roll in a stand, three stands, and a plurality of stands.

For example, in a normal forming process, the bending of the end of the metal strip in the breakdown stand is often performed in the first stand, or in both the first stand and the second stand. Therefore, the lower roll of the first stand (hereinafter simply referred to as "lower roll").

) into two roles. Also, the second
If the bending load of the end of the metal strip is higher on the stand than on the first stand, the lower roll of the second stand is also
Preferably, it is made into two rolls.

That is, the present invention is a welded pipe manufacturing apparatus in which the lower roll is composed of two rolls in at least one horizontal roll stand that mainly performs bending of the end of the metal strip in the initial stage of the roll forming process. The rotating shaft of these rolls is tilted with respect to the traveling direction of the metal strip, and the configuration is such that the movement can be adjusted relative to the traveling direction of the metal strip, or the rotation axis of these rolls can be adjusted in the axial direction of the upper roll. That's what I do.

(Function) The present invention will be described in more detail below along with examples. Note that this is merely an example of the present invention, and the present invention is not unduly limited thereby.

FIGS. 1(a) and 1(b) are schematic illustrations of the roll arrangement of the apparatus according to the present invention, and FIG. 1 (al is a side view, FIG. 1tb) is a top view. In at least one horizontal roll stand that is mainly responsible for edge bending, the lower roll 3 is composed of two rolls of 5.5°, and as shown in FIG. 1(b), the lower roll 3 is 90
There exists an inclination β (inclination angle) with respect to the direction where the angles intersect. In addition, in FIG. 1 fat, the rotating shaft of the lower roll 3 has an angle γ with respect to the feeding direction of the metal strip, but this is not particularly relevant to the effects of the present invention, and γ=06. You can.

Cross sections in the direction perpendicular to the traveling direction of the metal strip when the metal strip is fed to a stand with such a roll arrangement, that is, the Y-Y cross section, the YY'' cross section, and the Y'' cross section in FIG. 1(b).
-Y'' cross section Fig. 1 fc), Fig. 1 (dl and Fig. 1 (
It is also shown in Q). In other words, Fig. 1 fc) is the cross section of the fed metal band 4 when it starts contacting the upper roll 2 and the lower roll 5, and Fig.
This is the cross section at the time when the edge bending of the metal strip 4 is completed at the center position. Figure 1 + d) is also Figure 1 (C
1 and FIG. 1(a). As is clear from Fig. 1 (C1 to Fig. 1 (Ql), the contact point between the lower roll 5.5゜ and the metal band 4 is the metal band because each lower roll 5.5゜ has an inclination angle β. As the bending of the metal strip 4 progresses, the ends of the metal strip 4 do not receive a concentrated load at one point.Therefore, the thickness of the metal strip 4 does not decrease at the end of the metal strip 4. Roofing does not occur because sufficient bending can be performed to the ends.

Furthermore, even when bending metal strips with different thicknesses, the rolling reduction of the upper roll 2 is adjusted, and each lower roll 5.5° is installed movably in the metal strip advancing direction or in the upper roll axial direction. By doing so, the arrangement is such that the metal strip 4 can be sufficiently formed to the end. For thin materials, bending the edges increases the rigidity of the edges and is effective in preventing edge buckling. Therefore, the same roll can sufficiently bend the edges of thin to thick materials, effectively preventing edge buckling when bending thin materials and roofing when bending thick materials. It can be prevented.

It goes without saying that installing the lower roll so that it can move freely in the advancing direction of the metal strip and installing the lower roll so that it can move freely in the axial direction of the upper roll can be done separately or together. . Furthermore, the lower roll is not limited to the grooved roll shown in the example shown, but may be a cylindrical roll with the same outer diameter in the axial direction or two rolls obtained by dividing a Taber cylindrical roll with the minimum diameter at the axial center into two. You can.

In addition, in order to install the lower roll so that it can move freely in the advancing direction of the metal strip, or to install the lower roll so that it can move freely in the axial direction of the upper roll, for example, the roll can be moved mechanically using a morph. Examples include means for moving the rolls using hydraulic pressure, and the like.

Further, the present invention will be specifically explained with reference to examples thereof.

Example 1 Two types of steel plates with thicknesses of 1 V++ and 0.7 V++ were roll-formed using a conventional method and the method of the present invention using a single stand, and their formability was compared.

FIG. 2 is a schematic explanatory diagram showing the roll shape of the conventional method at this time, and the radius of curvature R of the upper roll was 2011N. Further, the radius of curvature 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 diagram in FIG. 3, the lower roll was divided into two rolls of 5.5", and the inclination angle β was set to 30".

The edge thickness distribution after passing through a single stand in the case of a steel plate with a thickness of 10+u+ is shown graphically in FIG. The method of the present invention (11 in Fig. 4 is a method in which the lower roll is moved in the traveling direction of the metal strip to make adjustments.The method of the present invention (2) is the method in which the lower roll is moved in the axial direction of the upper roll. , which has been adjusted.

As is clear from Fig. 4, in the conventional method, a decrease in the thickness of the steel plate at the end portion occurred by 2111I, but according to the present invention (1)
Alternatively, it can be seen that according to the method shown in (2), almost no reduction in the thickness of the steel plate occurs.

Next, the inner curvature after single stand molding is shown in Figure 5 (al, Figure 5).
As shown in Figure (bl) and Figure 5 (C1).As shown in Figure 5 (al), in the case of thick-walled materials, the conventional method
It was not possible to bend the edges of the steel plate.

On the other hand, in the method shown in (11 or (2)) according to the present invention, it was possible to sufficiently bend the steel plate to the end of both the steel plates having a thickness of 1 ha+ and 0.7 ms+.

Example 2 The roll arrangement according to the present invention was applied to the first stage roll stand of a roll forming device of a conventional electric resistance welded pipe manufacturing device, and the outer diameter was 50.8 wm, the wall thickness was 10IIIl, and 0.7 am.
(7) A welded pipe was manufactured using a steel plate. Note that a grooved roll was used as the lower roll, the inclination angle of this lower holed roll was 30°, and welding was performed by electric resistance welding.

As a result, with a steel plate having a wall thickness of 1 mm, no roofing occurred because the thickness of the steel plate did not decrease at the end. Further, in the case of a steel plate with a thickness of 0.7 mm, edge buckling occurred in the conventional method, but in the method of the present invention, edge buckling did not occur at all because the edges were sufficiently bent.

(Effects of the Invention) As described in detail above, according to the present invention, both ends of a metal strip can be sufficiently bent and formed, regardless of whether it is a thick-walled material or a thin-walled material. This is of great significance because it can effectively prevent roofing of thick-walled materials, and also prevent edge bank ringing of thin-walled materials.

In addition, by adjusting each lower roll in the advancing direction of the metal strip or in the axial direction of the upper roll, changes in plate thickness can be accommodated, and unlike conventional methods, there is no need to change the rolls, making it practical. The effect is also extremely significant.

[Brief explanation of the drawing]

Figure 1fa), Figure 1tb), Figure 1(C), Figure 1+
d) and FIG. 1 te+ are a schematic explanatory diagram illustrating the arrangement of the upper and lower rolls of the forming stand of the welded pipe manufacturing apparatus according to the present invention; FIG. 2 is a schematic explanatory diagram showing the roll shape of the conventional method; FIG. 3 4, 5 (al), 5 (t+) and 5 (
C, l are graphs summarizing the results of the examples; FIG. 6 is a schematic cross-sectional view showing the shape of a thick-walled material produced by a conventional method; FIG. 7+a+ and 711g (bl are thin-walled materials, A schematic explanatory diagram showing the roll biting state of meat material; and the eighth
Figures (al, Figure 8 (bl), Figure 8 (C1 and Figure 8 (
dl is a schematic explanatory diagram of the contact state between the roll and the molding material. 1: Welded steel pipe 2: Upper roll 3: Lower roll 4: Metal strip 5.5”: 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 two rolls, and (ii) its rotation axis is inclined in the metal strip traveling direction. Become,
Furthermore, (iii) a welded pipe manufacturing apparatus characterized in that the welded pipe manufacturing apparatus is installed movably in the advancing direction of the metal band and/or in the axial direction of the upper roll.