JPS60111783A - Production of electric welded pipe - Google Patents

Abstract

PURPOSE:To obtain an electric welded steel pipe having excellent shape quality by using squeezingly supporting and forming means for forming both of the both edge parts at the joint of a pipe stock and both side parts of the pipe stock in the position just before the 1st fin pass rolls and in the intermediate positions of respective fin pass rolls. CONSTITUTION:Edge squeezing rolls 36 which can support squeezingly both edges 26a of the joint of a pipe stock 26 are provided in the position just before the 1st fin pass rolls 20. Side squeezing rolls 46 which can support squeezingly both sides of the pipe stock are provided so that both of both edges 26a of the joint and both side parts of the pipe stock can be simultaneously and continuously squeezed and supported. Edge squeezing rolls 38 which can support squeezingly both edges 26a of the pipe stock are provided in the intermediate positions of respective fin pass rolls 20, 22, 24. Side squeezing rolls 48 which can support squeezingly both side parts of the pipe stock are provided so that both of both edges 26a of the joint and both side parts of the pipe stock can be simultaneously and continuously squeezed and supported.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing an electric resistance welded steel pipe.

Generally, ERW steel pipe is made using cage roll forming method, step o
-Manufactured using manufacturing equipment based on roll forming method, semi-cage roll forming method, etc.

That is, in the manufacturing equipment based on the cage roll forming method shown in FIGS. 1 and 2, for example, the strip plate 10 is formed using breakdown rolls 12. Edge forming roll 14, Ara I side cage roll 16
After being successively formed into a cylindrical shape by the inside cage roll 18, as shown in enlarged form in FIGS. By being sequentially rolled down in the pipe circumferential direction by the pass rolls 22 and the third fin pass rolls 24, the raw pipe 26 is finished formed into a predetermined pipe shape and size while stably forming the edge portion.

The blank 126 rolled down in the circumferential direction of the pipe by each of the fin bath rolls 201, 22, and 24 in L is subjected to high-frequency heating at both joint edges 26a, and is upset-welded by the squeeze roll 28 to become an electric resistance welded steel pipe 30. In addition, the weld bead 32 raised due to upset welding is removed by the squeeze roll 2.
The beads are cut and removed by a bead cutting device 34 installed on the downstream side of the beads 8. In addition, in the figure, 20a, 22
a, 24a indicates the lower roll, 20b, 22b.

24b shows a side roll, 20c, 22c.

24c indicates the lower roll.

In the manufacturing process of the above-mentioned electric resistance welded tube, the forming condition of both edges of the strip plate is extremely important, and if the edge forming is defective, it will lead to a decrease in the shape quality of the welded part and a decrease in material yield. . In particular, the leading and trailing ends of the strip become unsteady regions of forming, where the restraint applied to the strip is weak, and the strip tends to fluctuate because almost no tension is applied in the longitudinal direction, and each fin path The springback of the raw pipe increases after passing through the stand. This results in forming defects such as asymmetric bending of both the left and right edges, insufficient bending of the edges, and generation of edge waves, which is a bigger problem than the material yield.

By the way, in the method for forming the electric M steel pipe, the method of restraining the raw pipe between the tandem type fin pass roll stands is extremely important from the viewpoint of stabilizing the edge forming of the raw pipe. In particular, when forming the unsteady portion at the leading and trailing ends of the strip, the forming conditions between the fin pass roll stands determine the stability of the raw tube edge forming. Therefore, in conventional fin pass forming, edge restraint rolls or edge restraint shoes that continuously restrain and support the edge portion of the raw pipe are installed immediately before the first fin pass stand and between each fin pass stand, and the edge of the raw pipe is formed. We are trying to stabilize the situation. 3 to 5 show an example of the edge restraint rolls 36 and 38 installed immediately before the first fin pass roll and in the middle of each fin pass roll in the conventional forming method described above. . FIG. 6 shows an example of installation of the work/engine restraining shoe 40.

However, in the conventional fin pass forming described above,
Immediately before the first fin pass roll and in the middle of each fin pass roll, only the edges of the raw pipe are constrained, so the material between the stands is weakly constrained, and if only the edges are restrained, the raw pipe cannot be formed properly. It springs back and deforms in the width direction, becoming a horizontally long blank tube with a wide edge opening.

In this way, when forming an oblong blank tube with spring buckles in the width direction using the subsequent fin pass rolls,
On the contrary, it may lead to defective edge molding. In particular, when forming the unsteady portion at the front and rear ends of the strip, the raw tube will undergo a large springback in the width direction after passing through each fin pass roll, so when forming at the next stand, the edge portion of the raw tube will be formed. Causes defects. In particular, when forming unsteady parts at the tip of thin-walled materials, the springback at the tip of the raw tube after passing through each fin pass roll is extremely large. This causes sudden bending deformation of the edge portion and side portion of the tube. When such sudden width-closing bending deformation occurs, a sudden compressive force acts on the edge portion of the blank pipe in the longitudinal direction, and the direction of the compressive force acts on the edge portion in the longitudinal direction. This causes edge waves to be generated at the edges of the raw pipe between the fin pass roll stands. Once such edge waves are generated, edge waves continue to occur at the tip of the strip, resulting in an open pipe that cannot be welded. FIGS. 7 and 8 show t
FIG. 3 is a diagram showing the results of an investigation of the springback state of the tip of the raw tube after passing through the first fin pass roll in a material having a ratio of /D (thickness/outer diameter) of 1.0%. FIG. 7 shows the relationship between the edge opening width and the first fin path reduction area, and FIG. 8 shows the relationship between the raw pipe opening width (vertical diameter/horizontal frame) and the first fin path reduction area. Note that the investigations shown in Figures 7 and 8 were conducted when there was no edge guide roll between the first fin pass roll and the second fin pass roll. It is recognized that the horizontal frame of the raw pipe increases and the vertical diameter of the raw pipe decreases, that is, springback occurs in the width direction. That is,
In the case of the conventional edge restraint support method, it is not possible to sufficiently suppress the above-mentioned sprinkling back in the width direction, which results in the occurrence of the above-mentioned defective two-way molding. In particular, in forming thin materials, a forming method in which the amount of first fin pass reduction is increased is generally used in order to stabilize the forming of the steady portion of the strip. In this case, as shown in FIGS. 7 and 8, the amount of springback at the tip of the blank tube increases, and the occurrence of edge forming defects at the tip of the blank tube becomes more severe.

In other words, the conventional method of restraining and supporting the raw pipe between finpass roll stands cannot sufficiently prevent the springback of the raw pipe, resulting in poor forming of the raw pipe edges, such as generation of edge waves and defective edge bending. This results in an open pipe that cannot be welded, resulting in a decrease in material yield.

Furthermore, in the production of conventional electric resistance welded steel pipes as described in 1.
As shown in FIG. 4, the final fin pass roll 2
4 and squeeze roll 28
The final fin pass roll 24 and the squeeze roll 28 are used to suppress the springback of the fin pass roll 24 and the squeeze roll 28 in order to suppress the springback of the pipe 6a and stabilize the edge forming, as well as to prevent fluctuations in the raw pipe edge 26a during upset welding by the squeeze roll 28.
One or two seam guide rolls 42 are installed between the base pipe and the base pipe to restrain and support the raw pipe edge portion. Figure 9 shows
4 is a sectional view taken along line IX-IX in FIG. 3. FIG.

By the way, in order to suppress the springback of the raw pipe edge between the final fin pass roll and the squeeze roll by the seam guide roll as described above, and to prevent the edge fluctuation, it is necessary to adjust the pressure of the seam guide roll. However, when using the constraint support forming means using the seam guide rolls, even if the pressure of the seam guide rolls is strengthened in order to strengthen the restraint of the edges of the raw pipe, the raw pipe does not move in the width direction as shown in Fig. 10. Because it has a degree of freedom, it bulges in the width direction and has a horizontal oval shape.
It becomes difficult to form a sufficient restraint state of the raw pipe edge by the seam guide roll. Furthermore, even if the rolling force of the seam guide rolls is strengthened, an edge-worn condition occurs in which the edges of the raw pipe collapse toward the inner surface of the pipe, resulting in poor welding by the squeeze rolls in the subsequent process.

In addition, in the constraint forming of the raw pipe edges using the seam guide rolls, the seam guide rolls are rolled down as described above in order to increase the restraining force, but at this time, the raw pipe bulges in the width direction and deforms. This results in a horizontal oval shape blank tube. When such a horizontal oval-shaped blank tube is formed by an almost perfectly circular squeeze roll in the next process, the side portion of the blank tube, which exhibits the above-mentioned bulging deformation, undergoes rapid width-shrinking deformation in the direction of the inner surface of the tube. . Due to the influence of this width-approaching deformation, the edge of the raw pipe fluctuates, making upset welding with squeeze rolls unstable. For this reason, in the conventional forming method using seam guide rolls, wrapping of the seam edge of the raw pipe as shown in Fig. 1 and fluctuation of the V-shape angle formed by the seam edge of the raw pipe in the longitudinal direction occur, resulting in cold This results in the occurrence of union defects and overweld defects.

In addition, when forming the unsteady portion at the leading and trailing ends of the strip, the raw tube undergoes a large springback in the width direction after passing through the final fin pass roll, so the conventional forming method using seam guide rolls cannot The edges of the pipe cannot be restrained sufficiently, and the edge portion of the raw pipe tends to fluctuate, leading to poor forming by squeeze rolls and poor welding.

In particular, when forming unsteady parts at the tip of thin-walled materials, the springback at the tip of the raw tube after passing through the final fin pass roll is extremely large, so when the raw tube enters the squeeze roll in the next process, the side of the raw tube A sudden bending deformation is performed at the edges and edges. When such sudden width-closing bending deformation is performed, a sudden compressive force in the longitudinal direction acts on the edge portion of the raw tube, and edge waves 44 as shown in FIG. 12 are generated at the edge portion of the raw tube. However, welding becomes impossible.

In other words, in the above-mentioned conventional method for restraining and supporting forming the edge portion of a raw pipe in which a seam guide roll is disposed between the final fin pass roll and the squeeze roll, the edge portion of the raw pipe is deformed by bulging in the width direction. This results in upset welding using squeeze rolls, especially wraps at the joint edges of the raw pipe, welding defects due to fluctuations in welding phenomena, and fluctuations in the raw pipe tip and back. This leads to the occurrence of edge waves, etc., resulting in a decrease in material yield and a decrease in welding quality.

The first aspect of the present invention is to suppress the springback of the raw tube between the fin pass roll stands and stabilize the forming of the raw tube edge, especially the unsteady part at the tip and rear end of the raw tube, thereby improving the material yield. An object of the present invention is to provide a method for manufacturing an electric resistance welded steel pipe, which enables the manufacture of electric resistance welded steel pipes with high welded part shape quality.

The second aspect of the present invention is to suppress the springback of the raw pipe between the fin pass roll stands, suppress the spring back of the raw pipe between the final fin pass roll and the squeeze roll, and By reinforcing the constraint of the part, we are able to stabilize upset welding with squeeze rolls and stabilize the edge forming of the unsteady part at the tip and rear end of the raw tube, resulting in high material yield and excellent resistance welding shape quality of the welded part. An object of the present invention is to provide a method for manufacturing an electric resistance welded steel pipe that enables the manufacture of steel pipes.

In order to achieve the above object, the first aspect of the present invention
The steel pipe manufacturing method involves simultaneously forming both joint edges of the raw pipe located immediately before the first fin pass roll and intermediate positions between each fin pass roll and both side parts of the raw pipe using a continuous restraint support forming means. It was designed to do so.

Further, the method for manufacturing an electric resistance welded steel pipe according to the second aspect of the present invention is as follows:
Joint I of the raw pipe located at the position just before the fin pass roll and at the intermediate position between each fin pass roll] Both edge parts and both side parts of the raw pipe are simultaneously formed by a continuous constraint support forming means, and the final fin pass is Both edge portions of the joint of the raw tube located at an intermediate position between the roll and the squeeze roll and both side portions of the raw tube are simultaneously formed by a continuous constraint support forming means.

Embodiments of the present invention will be described below with reference to the drawings.

13 to 15 are explanatory diagrams showing a first embodiment of the present invention, and members similar to those in the conventional example are given the same reference numerals.

In this first embodiment, as in the conventional example, a cylindrical strip is rolled by a tandem type first fin pass roll 20, second fin pass 20-roll 22, and third fin pass roll 24. The tube is sequentially rolled down in the circumferential direction to finish forming the tube 26, and the joint edges 2 of the tube 26 are formed.
6a is upset welded using squeeze roll 28,
This makes it possible to obtain an electric resistance welded steel pipe 30.

Therefore, in this first embodiment, an edge restraining roll 36 that can restrain and support both joint edge parts 26a of the i'126 is provided at a position immediately before the first fin pass roll 20, and an edge restraining roll 36 is provided at a position immediately before the first fin pass roll 20, and an edge restraining roll 36 is provided that can restrain and support both joint edge parts 26a of the i'126. 26b is provided with side restraint rolls 46 that can restrain and support the seam both edge portions 26.
Both the base pipe side portions 26b and the base pipe side portions 26b can be simultaneously and continuously subjected to restraint support molding. In addition, each fin pass roll 2
At the intermediate position of 0.22.24, edge restraint rolls 38 are provided that can restrain and support both edge portions 26a of the raw pipe, and side restraint rolls 48 are provided that can restrain and support both side parts 26b of the raw pipe. Both joint edge portions 26a and both side portions 26b of the raw pipe can be simultaneously and continuously constrained and supported. In addition, in this first embodiment,
As shown in FIG. 16, the edge restraint roll 36.
38 may be replaced by edge restraint shoes 40, and the side restraint rolls 46, 48 may be replaced by side restraint shoes 50. Here, the set positions of the edge restraint rolls 36, 38 and edge restraint shoes 40 in the vertical direction can be adjusted, and the positions of the side restraint rolls 46, 48 and the side restraint shoes 50 in the width direction can be adjusted. has been done.

1- According to the first embodiment, the springback of the raw pipe;
In particular, it is possible to suppress springback in the width direction and stabilize edge forming in fin pass roll forming.

In addition, in the above-mentioned first embodiment, a case was explained in which a restraint roll and a restraint shoe were used as means for continuously restraining and supporting the raw pipe edge part and the raw pipe side part, but the restraint support molding used in carrying out the present invention The means include each restraint roll 36, 38, 46, 48 and restraint shoe 40.5.
Not limited to 0, but substantially the feature of the present invention is that the edge portion of the raw tube and both side portions of the raw tube are simultaneously and continuously restrained and formed immediately before the first fin pass stand and between each fin pass' stand. A restraining means having a shape and structure other than the above-mentioned restraining rolls and restraining shoes may be used as long as the springback of the tube can be suppressed.

In addition, in the present invention, the restraint support forming of the side portion of the raw pipe between each fin pass roll stand is such that the part from the exit side of the front fin pass roll to the input side of the rear fin pass roll is continuously and precisely restrained and supported. The higher the continuity, the more stable edge forming in fin pass forming becomes possible. In particular, the edge forming of the unsteady part at the tip and rear end of the raw pipe has been greatly improved and the yield has improved! It becomes possible to aim for improvement.

]-The following results were obtained by applying the molding method shown in FIGS. 13 to 15 to an actual mill. That is,
Outer diameter 24 inches, plate thickness 6, 35 mm, pipe standard API
5LX-X60 (7) When an electric resistance welded steel pipe was manufactured by the conventional forming method and the method according to the first embodiment described above, it was found that the edge forming of the unsteady part at the tip and rear end of the raw pipe was It was observed that the nap length decreased by 70% due to defects, and the pass rate of the welded part in the ultrasonic test increased by 0.5%.

FIGS. 17 to 18 are explanatory diagrams showing main parts of a second embodiment of the present invention.

In this second embodiment, in exactly the same way as in the first embodiment, a cylindrical strip 10 is sequentially rolled down in the pipe circumferential direction by a plurality of fin pass rolls 20, 22, 24 to form a base pipe 26. Finish molding is performed to form the seam of both edges 26 of the raw pipe 26.
In the "A" manufacturing method of the ERW steel pipe 30 in which the ERW steel pipe 30 is upset welded by the squeeze roll 28, the position immediately before the first fin pass roll 2o and each fin pass roll 2o, 2
2. Both joint edge portions 26a and both side portions 26b of the raw pipe 26 located at the intermediate position of
Between the fin pass roll 24 and the squeeze roll 28,
As shown in FIGS. 17 and 18, seam guide rolls 42 are provided that can restrain and support both joint edges 26a of the raw pipe 26, and side guide rolls that can restrain and support both side parts 26b of the raw pipe. 52, it is possible to simultaneously and continuously perform restraint support molding on both joint edge portions 26a and both side portions 26b of the raw tube. here,"
: The seam guide rolls 42 and side guide rolls 52 can be adjusted in their setting positions below -L or in the width direction.

In the above embodiment, as a means for simultaneously continuously restraining and supporting forming the joint edge part of the raw pipe and both side parts of the raw pipe,
Although the case where three sets of restraint guide rolls are used has been described, the means used to carry out the present invention is not limited to the guide rolls 42 and 52 described above, and restraint means having shapes and structures other than these can be used. Often, both edges of the raw pipe joint and both side parts of the raw pipe between the final fin pass roll and the squeeze roll are simultaneously and continuously constrained and supported, which is a feature of the present invention, to prevent bulging deformation or spring of the raw pipe side part. Other shapes and structures may be used as long as they can suppress backing, strengthen the restraint of both edges of the raw pipe joint, and stabilize welding and forming.

In addition, the constraint support molding of the joint edge and side portions of the raw pipe in the second embodiment is such that the constraint support is continuously and precisely formed from the exit side of the final fin pass roll to the input side of the squeeze roll in the next process. The higher the continuity, the more stable the upset welding of the joint edges of the raw pipes and the edge forming of the front and rear ends of the raw pipes can be stabilized.

When the molding method shown in FIGS. 17 and 18 was applied to an actual mill, the following results were obtained.

That is, when an electric resistance welded steel pipe with an outer diameter of 24 inches, a plate thickness of 6.35 mm, and a pipe specification API5LX-X60 was manufactured by the conventional forming method and the method according to the second embodiment, t5
Figures 19 and 20 were obtained.

FIG. 19 shows relative fluctuations in the height direction of the joint edge portions of the raw pipe in the vicinity of the squeeze roll, and FIG. 20 shows fluctuations in the edge spacing in the width direction. This figure 19 and 20
According to the figure, according to the second embodiment, fluctuations in the joint edge of the raw pipe due to the squeeze roll are reduced, and upset welding is significantly stabilized. That is, according to the second embodiment, the occurrence of laps in the seam width and welding defects in the welded part was reduced, and the occurrence of welded part failure rate by ultrasonic testing was reduced by 53%. Additionally, the length of the unwelded open tube due to defective edge forming at the unsteady portion at the tip and rear end of one tube was reduced by 45%.゛The present invention is not limited to the forming method in the upstream forming area of ERW steel pipes, but can be widely applied to any forming method such as cage roll forming method, step roll forming method, vertical roll forming method, etc. It is. Furthermore, the present invention is applicable to fin pass roll forming with other numbers of stands, and is not limited by the division method of the fin pass rolls, nor is it limited by the structure of the squeeze roll.

As described above, the method for manufacturing an electric resistance welded steel pipe according to the first aspect of the present invention is applicable to the joint edge portions of the raw pipe located immediately before the first fin pass roll and the intermediate position of each fin pass roll, Both side portions are molded simultaneously by a continuous constraint support molding means. therefore,
By suppressing the springback of the raw tube between the fin pass roll stands and stabilizing the forming of the raw tube edge, especially the unsteady part at the tip and rear end of the raw tube, we have achieved a high material yield and welded part shape quality. This makes it possible to manufacture superior ERW steel pipes.

Further, the method for manufacturing an electric resistance welded steel pipe according to the second aspect of the present invention is as follows:
Both edges of the joint of the raw pipe and both side parts of the raw pipe located at the position just before the fin pass roll and at the intermediate position between each fin pass roll are simultaneously formed by a continuous constraint support forming means, and the final fin pass roll and Both edge portions of the joint of the raw tube located at an intermediate position with the squeeze roll and both side portions of the raw tube are simultaneously molded by a continuous constraint support forming means. Therefore, by suppressing the springback of the raw pipe between the fin pass roll stands, suppressing the spring back of the raw pipe between the final fin pass roll and the squeeze roll, and strengthening the restraint of the raw pipe edge part, By stabilizing upset welding with squeeze rolls and stabilizing edge forming at the unsteady portion at the tip and rear end of the tube, it is possible to manufacture ERW steel pipes with high material yield and excellent welded part shape quality. .

[Brief explanation of drawings]

Figure 1 is a plan view showing a production line for ERW steel pipes based on the cage roll forming method, Figure 2 is a side view of Figure 1, and Figure 3 is a side view of Figure 1.
4 is a side view of FIG. 3, FIG. 5 is a sectional view taken along the line V-v of FIG. 3, and FIG. FIG. 6 is a sectional view showing a different aspect from FIG. Fig. 8 is a diagram showing the relationship between the aperity of the tip of the blank tube after passing through the first fin pass roll and the first fin pass reduction, and Fig. 9 is a sectional view taken along line IX-IX in Fig. 3. Fig. 10 is a schematic diagram showing the main parts of Fig. 9, Fig. 11 is a cross-sectional view showing the lapped state of the raw pipe joint edge that occurs during upset welding using conventional squeeze rolls, and Fig. 12 is FIG. 13 is a perspective view showing edge waves generated during conventional molding of an unsteady portion at the tip of a blank pipe; FIG. 13 is a plan view showing a fin pass molding region and a squeeze molding region according to the first embodiment of the present invention; 13 is a side view, FIG. 15 is a sectional view taken along the line XV-XV in FIG. 13, FIG. 16 is a sectional view showing a different aspect from FIG. 15, and FIG. 17 is a second embodiment of the present invention. A plan view showing the final fin pass forming area and squeeze forming area, FIG. 18 is a sectional view taken along the line X-X in FIG. FIG. 20 is a diagram showing the relative fluctuation, and is a diagram showing the distance between the edges of both joints of the raw pipe in the vicinity of the squeeze roll. 10... Strip plate, 20... First fin pass roll, 2
2...Second fin pass roll, 24...Third fin pass roll, 26...Main pipe, 26a...Both joint edges, 26b...Both side parts of the stock pipe, 28...Squeeze roll , 30... Electric resistance welded steel pipe, 36.38... Edge restraint roll, 40... Edge restraint shoe, 42...
- Seam guide roll, 46. 48... Side restraint roll, 50... Side restraint shoe, 52... Side guide roll. Agent Patent Attorney Osamu Shiokawa

Claims (2)

[Claims] (1) A cylindrical strip is sequentially rolled down in the circumferential direction of the tube using multiple fin pass rolls to form a finished tube.
In a method for manufacturing an ERW steel pipe in which the joint edges and joints of the raw pipe are upset welded by squeeze rolls, both edge parts of the joint of the raw pipe located at a position just before the first fin pass roll and at an intermediate position between each fin pass roll and 1. A method for manufacturing an electric resistance welded steel pipe, characterized in that both side parts of the raw pipe are simultaneously formed by a continuous constraint support forming means. (2) A cylindrical strip is sequentially rolled down in the pipe circumferential direction using multiple fin pass rolls to form a base pipe, and both edges of the joint of the base pipe are upset welded using squeeze rolls. In a method for manufacturing a sewn steel pipe, both edge parts of the joint of the raw pipe and both side parts of the raw pipe located at a position immediately before the first fin pass roll and at an intermediate position between each fin pass roll are simultaneously continuous by a restraining support forming means. At the same time, both the inner joint engine part of the raw pipe located at an intermediate position between the final fin pass roll and the squeeze roll and both side parts of the raw pipe are simultaneously molded by a continuous constraint support forming means. Manufacturing method of sewn steel pipe.