JP4508727B2 - ERW pipe manufacturing method - Google Patents

Description

The present invention, the plate thickness is thin walled electric-resistance-welded pipe with respect to the outer diameter of a method for producing a suitable electric-resistance-welded pipe is applied to the production of so-called low t / D electric-resistance-welded pipe.

  The electric sewing tube manufacturing apparatus is generally configured as shown in FIG. 5 which is common to the present invention and the conventional example. A strip-shaped metal plate 1 is passed through an inlet guide roll 13 and a plurality of breakdown rolls 2. Is formed into a substantially semicircular shape in a breakdown roll region 3 and then formed into a substantially circular shape in which both edges are close in a fin pass roll region 5 composed of a plurality of stages of fin pass rolls 4 and at the same time an outer diameter drawing Next, in the welded portion 8 including the squeeze roll 6 and the welding machine 7, both the materials of the substantially circular material (molded material) are energized and heated by the welding machine 7, and both the materials are used by the squeeze roll 6. The edges are butted against each other to form a tube. In the illustrated example, a cluster roll 11 including a plurality of side rolls 10 that press the material from the side is installed between the breakdown roll area 3 and the fin pass roll area 5.

  In the case of a low t / D ERW pipe having a thin plate thickness t with respect to the outer diameter D, it is easy to make butt welding in a state where the edge portion has a poor shape in the welded portion. It is difficult to manufacture the D electric sewing tube, and conventionally, the low t / D is limited to 1%.

There are two types of edge shape defects (edge edge butt shape failure): the shape of both edge parts is asymmetric and has a step, and the shape of the edge part is unsuitable for butt welding even if symmetrical. If the material (molded material) is introduced into the squeeze roll of the welded portion in such a state where the shape of the edge portion is defective, the butt welding becomes poorly welded. There are various causes for the butt welding in the state of such a defective shape of the edge portion.
(1) In breakdown molding (molding in the breakdown roll region), an edge wave 16 may occur at the edge portion as shown in FIG. In the case of low t / D, the edge wave of the edge portion is particularly likely to occur. When the edge wave is generated, a step 17 is generated between the two edges at the time of abutting both the edges in the welded portion as shown in FIG.
(2) In the fin pass molding (molding in the fin pass roll region), an outer diameter drawing process (hoop compression) is performed, but the edge portion of the material may be buckled by the applied pressure of the outer diameter drawing process. This buckling is also particularly likely to occur at low t / D.
In addition, the edge part of the fin pass roll is bent to a predetermined curvature, but the curvature radius of the edge part becomes large due to the springback of the material after passing through the fin pass roll (the phenomenon that the bending returns), and both edges May not be the original I groove but a V groove 18 as shown in FIG. In this case, of course, welding failure occurs.
In addition, although there is no problem in the butt shape of the edge portion, buckling may occur in the edge portion of the material in the butt welding process, that is, the upset pressure (circumferential compression force) in the squeeze roll during welding. . This buckling is also particularly likely to occur at low t / D.

In the present invention, there is a problem that an edge wave is generated in the edge portion of the material at the time of breakdown molding. The cause of the edge wave and conventional countermeasures will be described.
In breakdown molding, in which both edges are gradually raised with respect to the center and formed into an arc shape, the track length of the edge is longer than the track length at the center in the width direction of the material. Elongation, that is, edge elongation (edge elongation indicated by a in FIG. 6) occurs. Due to this edge extension, a compressive force in the longitudinal direction of the material acts on the edge portion until it becomes substantially circular by the fin pass roll, the edge portion buckles due to this compressive force, and an edge wave 16 is generated. The arrow (A) in FIG. 6 is the molding direction (material feeding direction).
Because of this generation mechanism, in order to prevent edge waves, it is necessary to suppress the elongation of the edge part as much as possible, but as measures to prevent edge waves, measures to downhill the pass line are widely adopted. . The pass line is a line that connects the designated points of the roll hole shape in each stand, and there are several ways to take the designated points, but here it is the same as in general tube forming In addition, the bottom point of the roll hole shape is adopted as the designated point, and a line connecting the bottom points of each roll hole shape (therefore, the lower surface at the center in the material width direction) is defined as a pass line.

FIG. 10 shows an example of a pass line design in the breakdown roll region from the entrance guide roll 13 to the entrance of the fin pass roll 4 in the conventional electric sewing tube manufacturing apparatus. As shown in the figure, in each stand, the path in which the material 1 enters with a downward inclination (entrance angles θ ₁ , θ ₂ , θ ₃ ) with respect to the path position of the roll 2 (the height position through which the material between the upper and lower rolls passes). It is a line L, and the locus of the lower surface in the center of the material width direction is a downhill pass line with a downward slope.
In addition, although the described patent documents 1 and 2 are common with this invention in the point aiming at manufacture of a thin electric sewing tube, there is no description about the downhill shaping | molding which is the principal part of this invention.
Japanese Patent No. 2788911 JP 58-196181

With reference to FIGS. 8 (a), (b), and (c), a phenomenon that is experimentally and empirically known about the relationship between the material entry angle and the material warpage tendency in the breakdown roll will be described. To do. In FIG. 8, 2 is a roll of one stand (upper and lower rolls) in a plurality of breakdown roll regions. In this figure, the material 1 is formed from a circular arc 1a having a certain curvature to a circular arc 1b having a smaller curvature (arc-shaped → arc-shaped). An arc shape can be considered in the same way. Since the breakdown roll 2 is formed by curving the material downward, the upper roll 2a is a convex roll and the lower roll 2b is a concave roll.
Conventionally, when the vertical roll direction of the breakdown roll 2 (referring to the direction connecting the centers of the upper and lower rolls) is vertical, and the material 1 is made to enter the path position of the roll 2 horizontally, the material formed by the roll Has a convex shape on the convex roll side (upper roll side) (ie, a convex shape on the upper side), that is, downward warping (FIG. 8 (A)). Further, when the material is entered at an approach angle with a certain downward slope with respect to the pass position of the roll 2, the roll is warped in relation to the approach angle, but is discharged horizontally on the roll exit side ( FIG. 8 (b)). If the roll 2 is made to enter at an approach angle with a further downward slope, it will eventually be discharged with an upward slope and will be in a deformed state of the ship bottom (FIG. 8 (c)). This is the behavior when one stand has the material height position fixing means on the entry side and is free on the exit side.

By the way, looking at the relationship between the warpage of the material and the distribution of the longitudinal strain in the width direction, the downward warpage is the elongation strain at the material edge and the compressive strain at the center, and conversely the upper warping is the compression at the material edge. The central part is strained by strain.
If it is downward warping, that is, if there is longitudinal elongation strain at the edge and compression strain at the center, considering that the material on the same surface in the longitudinal direction is welded in the welded part, it becomes a straight round tube, It means that compressive deformation occurs at the edge after the breakdown roll and before welding. That is, it means that buckling occurs at the edge and warping occurs due to buckling.
On the other hand, when it is warped, that is, when there is a longitudinal compressive strain at the edge and an elongation strain at the center, the compressive deformation that occurs at the edge before the breakdown roll and before welding is reduced, and buckling and hip breakage occur. It has the potential to be reduced. That is, positively warping the material entering the fin pass roll is an effective means for reducing the longitudinal compression of the edge between the fin pass roll and the squeeze roll. This is considered to be an effective means for preventing wave generation.

From the above, the true downhill pass line that should be adopted to suppress edge stretch (prevent edge wave generation) is a pass line that can be warped simultaneously on all stands. .
However, the downhill conventionally employed is not such a pass line as shown in FIG. If there is one stand, there is no problem in satisfying the above true downhill conditions, but considering the downhill conditions at each stand in a continuous multi-stage stand, the downhill conditions at the entrance The condition is satisfied, but the condition is not satisfied on the exit side. That is, in each stand, when the material enters with a downward slope on the entry side of the roll, the material is discharged upward from the roll, but receives a downward force from the roll on the downstream side (that is, the downward warp). Therefore, the downhill effect on the entry side is canceled on the exit side.

In view of such a background, the inventors examined the forming conditions that cause the material to warp, paying attention to the tendency of warping to the material entry angle as described in FIG. The idea was that the upper and lower rolls 2a, 2b are eccentric from each other, so that the downhill conditions can be satisfied on both the entry and exit sides of the roll.
The present invention has been made based on such a background, and it is possible to realize a true downhill to be adopted for suppressing the edge elongation, and a method for manufacturing an electric resistance tube capable of preventing the generation of edge waves of the material. The purpose is to provide.

In the invention of claim 1 for solving the above-mentioned problem, the belt-shaped metal plate is formed into a substantially circular arc shape in the breakdown roll region, and formed into a substantially circular shape with both edges approaching in the fin pass roll region. In the method of manufacturing an electric resistance welded tube, which is subjected to diameter drawing, and then butt welds both edges at a welded portion including a squeeze roll and a welding machine.
In the breakdown roll area including the front and rear stands, the path line, which is the forming direction locus in the center of the material width direction, is set to be inclined downward, and the upper roll is set for each of the plurality of breakdown rolls constituting the breakdown roll area. Eccentric to the downstream side with respect to the lower roll, so that the amount of eccentricity at the central portion in the material width direction is discharged at a downward discharge angle that is smaller than the entry angle when the material entered at a downward angle from the upstream side is discharged. In addition, the material discharge direction in each breakdown roll is set so as to be directed to the pass position of the downstream roll.

In the invention of claim 2, the belt-shaped metal plate is formed into a substantially circular arc shape in the breakdown roll region, and is formed into a substantially circular shape with both edges approaching in the fin pass roll region, and at the same time, an outer diameter drawing process is performed. Then, in the method of manufacturing an electric resistance welded pipe where both edges are butt-welded at a welded portion equipped with a squeeze roll and a welding machine,
In the breakdown roll area including the front and rear stands, the path line that is the forming direction locus in the center of the material width direction is set horizontally, and the upper roll is lowered for all of the plurality of breakdown rolls constituting the breakdown roll area. It causes eccentrically on the upstream side of the rolls, the eccentricity, in the material widthwise central portion, material has entered horizontally from the upstream side and setting so as to be discharged horizontally.
In the invention of claim 3, the belt-shaped metal plate is formed into a substantially circular arc shape in the breakdown roll region, and is formed into a substantially circular shape with both edges approaching in the fin pass roll region, and at the same time, an outer diameter drawing process is performed. Then, in the method of manufacturing an electric resistance welded pipe where both edges are butt-welded at a welded portion equipped with a squeeze roll and a welding machine,
In the breakdown roll area including the front and rear stands, the path line that is the forming direction locus in the center of the material width direction is set horizontally, and the upper roll is lowered for all of the plurality of breakdown rolls constituting the breakdown roll area. It is characterized in that it is eccentric to the upstream side with respect to the roll, and the amount of eccentricity is set so that the material that has entered horizontally from the upstream side is discharged at an upward angle at the center in the material width direction .

According to the invention of claim 4, the belt-shaped metal plate is formed into a substantially circular arc shape in the breakdown roll region, and is formed into a substantially circular shape with both edges approaching in the fin pass roll region, and at the same time, an outer diameter drawing process is performed. Then, in the method of manufacturing an electric resistance welded tube, in which both edges are butt-welded at a welded portion having a squeeze roll and a welding machine,
In the breakdown roll area including the front and rear stands, the path line, which is the forming direction locus in the center of the material width direction, is set to be inclined downward, and the upper roll is set for each of the plurality of breakdown rolls constituting the breakdown roll area. Eccentricity to the upstream with respect to the lower roll, and the amount of eccentricity is set so that the material that has entered at a downward angle from the upstream side is discharged at the same downward discharge angle as the entry angle at the center in the material width direction characterized in that it.
In the invention of claim 5, the belt-like metal plate is formed into a substantially circular arc shape in the breakdown roll region, and is formed into a substantially circular shape with both edges approaching in the fin pass roll region, and at the same time, the outer diameter is drawn. Then, in the manufacturing apparatus of the electric resistance welded pipe where both edges are butt-welded at a welded portion equipped with a squeeze roll and a welding machine,
In the breakdown roll area including the front and rear stands, the path line, which is the forming direction locus in the center of the material width direction, is set to be inclined downward, and the upper roll is set for each of the plurality of breakdown rolls constituting the breakdown roll area. Eccentricity is made upstream with respect to the lower roll, and the amount of eccentricity is set so that the material that has entered downward from the upstream side at the center in the material width direction is discharged at a downward discharge angle that is smaller than the entry angle. To do.

According to the invention of claim 1, as shown in FIG. 1, the eccentric amount δ with respect to the lower roll 2 b of the upper roll 2 a is appropriately set for each stand roll in the breakdown roll region (see FIG. 9 (B)). By doing so, it is possible to discharge the material that has entered at a downward angle from the upstream side at a downward discharge angle that is smaller than the entry angle. In other words, the material that has entered at a downward angle can be discharged substantially with a warp (relative warping with respect to the entry direction on the entry side), and the roll entry downhill condition can be satisfied. . In addition, even if each roll discharges the material substantially upwardly, the discharge angle is spatially downward, so that the material discharged from the roll does not receive downward pressing force by the downstream roll. Since there is no (that is, the downhill condition on the roll exit side is satisfied), there is no problem that the downhill effect on the entrance side is canceled on the exit side.
Since this action is obtained for each roll in the breakdown roll region, the downhill condition can be satisfied for all rolls in the breakdown roll region both on the entry side and the exit side of the roll. It can be performed. Thereby, the edge extension of the material in the breakdown roll region is suppressed, and therefore, the generation of the edge wave of the material is suppressed, and the cause of poor welding in the welded portion is improved.

According to the invention of claim 2, as shown in FIG. 3, in each roll 2 of the breakdown roll 3, the eccentric amount d with respect to the lower roll 2b of the upper roll 2a is appropriately set (see FIG. 9 (A)). As a result, the material 1 that has entered the roll 2 horizontally is discharged from the roll 2 horizontally (that is, discharged so that the material does not warp in the roll 2), and is therefore horizontal to the downstream roll. It is discharged so that it may enter. In this case, the molding shown in FIG. 9 (a) is horizontally equivalent to the portion discharged downward in FIG. 8 (a), and is therefore substantially equivalent to that discharged upward from the roll 2. is there. Therefore, it can be said that the entry side of each roll is equivalent to satisfying the downhill condition.
In addition, since the material discharged horizontally from each roll goes to the pass position of the downstream roll, the material discharged from each roll does not receive a downward pressing force by the downstream roll, There is no problem that the downhill effect is canceled on the exit side. In this way, even if it is a horizontal pass line, it is equivalent to satisfying the downhill condition on both the entrance side and the exit side of the roll, and a molding equivalent to a true downhill can be performed. Thereby, the edge extension of the material in the breakdown roll region is suppressed, and therefore, the generation of the edge wave of the material is suppressed, and the cause of poor welding in the welded portion is improved.

According to the invention of claim 3, the material 1 that has entered horizontally to the roll 2 is slightly upwardly discharged from the roll 2 (i.e. discharged as camber occurs in the material in the roll 2), therefore, the downstream It is discharged so as to enter slightly upward from the horizontal with respect to the pass position of the side roll. Then, the material discharged from the roll enters the downstream roll horizontally while being slightly pushed down by the downstream roll. However, if the push is slightly reduced, the material remains downstream while maintaining a substantially upward tendency. Enter the side roll.
If the material passes through the rolls of each stand with substantially large warping, there is a risk that a compressive force will act on the edge part and buckle will occur at the edge part, resulting in an edge wave. Is slightly lowered, and a slight tensile force acts on the edge portion of the material between the roll and the downstream roll, and the tensile force is applied to the edge between the roll and the downstream roll. It acts to prevent buckling, that is, edge waves, from occurring in the part. That is, it is effective for preventing the generation of edge waves in the breakdown roll region.

  The method of claim 1 is a pass line design in which the cross-sectional center of the molding material gradually decreases, and the method of claim 2 is a pass line design in which the cross-sectional center of the molding material gradually increases. According to the method of the invention of claim 4 or claim 5, it is possible to balance the whole by making the cross section center of the molding material constant or substantially constant, and the downhill effect at each stand can be further enhanced.

Hereinafter, the Example of the manufacturing method of the electric sewing pipe of this invention is described with reference to FIGS.

The structure of the main part of the manufacturing apparatus of the ERW pipe to which the present invention is applied is as schematically shown in FIG. 5 common to the above-described present invention and the conventional example, and a plurality of belt-shaped metal plates 1 are provided. In the breakdown roll region 3 composed of the step-by-step breakdown rolls 2, it is formed into a substantially semicircular shape, and then in the fin pass roll region 5 composed of the plurality of stages of fin-pass rolls 4, the both edges approach each other. At the same time as forming, the outer diameter drawing process is performed, and then in the welded portion 8 including the squeeze roll 6 and the welding machine 7, the material of the circular material 1 is energized and heated by the welding machine 7 with the squeeze roll 6. Both edges of 1 are butted against each other to form a tube. Then, the product is shaped into a final product shape by a plurality of subsequent sizing rolls 9. In the illustrated example, a cluster roll 11 composed of a plurality of side rolls 10 for pressing the material from the side is installed between the breakdown roll area 3 and the fin pass roll area 5. In addition, the thing including the flame | frame which supports each roll 2, 4, 10 is called a roll stand (or only a stand).
In the figure, 12 is an uncoiler, and 13 is an inlet guide roll. Normally, a pinch roll, a leveler, a material shearing machine and a relay welding machine, a looper, etc. are installed between the uncoiler 12 and the inlet guide roll 13, but these are omitted (14 indicates the inlet portion of the looper. )is doing. As the welding machine 7, a high frequency induction welding machine, a high frequency resistance welding machine or the like is generally used.

FIG. 1 shows an embodiment of an electric sewing tube manufacturing apparatus to which the electric sewing tube manufacturing method according to the first aspect of the present invention is applied. A breakdown forming pass line from an inlet guide roll 13 to a fin pass roll is shown. It is a figure explaining design. In the illustrated example, the breakdown roll region 3 is constituted by a three-stage breakdown roll 2, the fin pass roll region 5 is constituted by a two-step fin pass roll 4, and further a cluster roll region comprising a two-stage side roll 10. 11 is installed, but the number of stages is merely an example, and in actuality, it is designed to have an appropriate number of stages according to various conditions.

  An example of the hole shape of each roll in FIG. 1 is shown in FIG. In the illustrated example, the flat metal plate 1 passes through an inlet guide roll 13 that constrains at least the lower surface of the material 1, and is roughly arc-shaped with three breakdown rolls 2 (BDR # 1, BDR # 2, BDR # 3). The two-stage side roll 10 is pressed into the fin pass roll 4 while pressing the material from both sides, and the two-stage fin pass roll 4 (FPR # 1, FPR # 2) is used to bring both edges closer. It is finished and formed into a circular shape (in the illustrated example, a vertically long oval shape). The fin pass roll 4 has a fin roll 4f with which the edge of the material hits in the center of the upper roll 4a. Moreover, although the fin pass roll 4 of the example of illustration is the structure which also has the vertical roll 4c of both sides with the up-and-down rolls 4a and 4b, the structure which consists only of an up-and-down roll may be sufficient. The side roll 10 is actually a roll on both sides as shown in FIG. 2, but FIG. 1 shows a hypothetical lower horizontal roll 10 'in order to clarify the path position of the side roll region. However, in the case of forming a large diameter tube, the lower horizontal roll 10 'may be disposed.

In the invention of claim 1, as shown, the path line L ₁ of the breakdown molding leading to FPR # 1 from the inlet guide roll 13 is set to downhill, and the roll 2a over each breakdown roll 2, respectively Eccentricity is made downstream with respect to the lower roll 2b.
In the central portion of the material width direction, the material 1 that has entered at a downward angle from the upstream side is discharged at a downward discharge angle that is smaller than the entry angle , and the material discharge direction in each breakdown roll 2 is the downstream side. Set to go to the roll pass position. As a result, the material that has entered at the downward angle is discharged substantially in a warp (relative warping relative to the entry direction on the entry side), and the downhill condition on the roll entry side is satisfied.

An example of a specific method for setting as described above will be described.
Overall, the upper roll 2a of each breakdown roll 2 is eccentric with respect to the lower roll 2b by a predetermined eccentric amount in order from the FPR # 1 toward the upstream with the horizontal line having the origin at FPR # 1 as a reference. Therefore, it is set so that the downhill condition is satisfied in all the breakdown roll stands. When the upper roll 2a is eccentric to the downstream side with respect to the lower roll 2b, the upper roll chock that supports the upper roll shaft is disposed downstream of the lower roll chock that supports the lower roll shaft.
(1) The gradient α of the lower surface in the material width direction of the side roll 10 region with FPR # 1 as the origin is appropriately set. This gradient α is set to an appropriate value empirically. The material discharge direction in BDR # 3 is determined from the extended line of the gradient α.
(2) The upper roll is decentered in the horizontal direction by δ ₃ so that the vertical roll direction of the BDR # 3 stand (referred to as the direction connecting the centers of the vertical rolls) is the same as the gradient α on the BDR # 3 exit side.
(3) The material entry angle θ ₃ to BDR # 3 is determined experimentally or empirically such that the material is discharged from BDR # 3 in the direction of the gradient α.
(4) The eccentric amount δ ₂ of the upper roll of the BDR # 2 stand is calculated from θ ₃ .
(5) Similar to the BDR # 3, such as material from the BDR # 2 is discharged at an angle theta ₃ direction, the BDR # entry angle theta ₂ of the material to 2, determined experimentally or empirically.
(6) on than theta ₂ of the BDR # 1 stand to compute the eccentricity [delta] ₁ of the roll.
(7) Like the BDR # 2, as material from the BDR # 1 is discharged to the angle theta ₂ direction, the material entry angle theta ₁ of the BDR # 1, determined experimentally or empirically.

In the breakdown forming by the pass line design shown in FIG. 1, the eccentric amount δ with respect to the lower roll 2b of the upper roll 2a is appropriately set for each roll 2 of each stand in the breakdown roll region 3 (see FIG. 9B). Thus, the material 1 that has entered from the upstream side at a downward angle is discharged at a downward discharge angle that is smaller than the entry angle. In other words, the material that has entered at a downward angle is discharged substantially by warping (relatively warping relative to the entry direction on the entry side), and the downhill condition on the roll entry side is satisfied. In addition, even if each roll discharges the material substantially upwardly, the discharge angle is spatially downward, so that the material discharged from the roll does not receive downward pressing force by the downstream roll. Since there is no (that is, the downhill condition on the roll exit side is satisfied), there is no problem that the downhill effect on the entrance side is canceled on the exit side.
Since this action is obtained for each roll in the breakdown roll region, the downhill condition can be satisfied for all rolls in the breakdown roll region both on the entry side and the exit side of the roll. It can be performed. Thereby, the edge extension of the material in the breakdown roll region is suppressed, and therefore, the generation of the edge wave of the material is suppressed, and the cause of poor welding in the welded portion is improved.

  In the roll hole shape shown in FIG. 2, the material is formed into a vertically long ellipse by the fin pass roll 4. By forming the material into an oblong ellipse, the radius of curvature near both edges of the material is reduced. For this reason, the butt pressure (= upset pressure = circumferential direction) when the material edge is butted in the squeeze roll of the weld The rigidity with respect to the compression force is increased, the edge portion can be prevented from buckling or deforming due to the butt pressure, and poor welding can be prevented.

FIG. 3 shows an embodiment of the electric sewing tube manufacturing apparatus to which the invention of claim 2 is applied , and is a diagram for explaining a pass line design for breakdown forming from the inlet guide roll 13 to the fin pass roll. . As shown, set the inlet guide roll 13 FPR # pass line L ₂ breakdown molding leading to 1 from horizontal, and the upstream roll 2a over each breakdown roll 2 with respect to each under roll 2b And the amount of eccentricity δ is set so that the material that has entered horizontally from the upstream side is discharged horizontally at the center in the material width direction. That is, warp material is set so as not to generate in the breakdown roll 2.

An example of a specific method for setting as described above will be described.
The overall idea is to provide each stand with an up-roll eccentric amount that eliminates the warp on the exit side in all the break-down rolls, and eliminates edge elongation without any downhill.
(1) A horizontal pass line with FPR # 1 as the origin is set.
(2) In each roll of the BDR # 1 to # 3 stand, the material that horizontally enters the roll 2 is discharged horizontally from the roll 2 (that is, the material does not warp in the roll 2). The eccentric amounts d _{1 to} d ₃ are determined experimentally or empirically with respect to the lower roll 2b of the upper roll 2a. In this case, by applying the experimental facts described in FIG. 9 (b), to determine the eccentricity d ₁ to d ₃ with respect to the lower roll 2b of upper roll 2a.

In the pass line design of FIG. 3 described above, each roll 2 of the breakdown roll 3 has the eccentric amount d with respect to the lower roll 2b of the upper roll 2a appropriately set (see FIG. 9 (a)). 2 is discharged horizontally (that is, discharged so as not to warp the material in the roll 2), that is, discharged so as to enter the downstream roll horizontally. In this case, the molding shown in FIG. 9 (a) is horizontally equivalent to the portion discharged downward in FIG. 8 (a), and is therefore substantially equivalent to that discharged upward from the roll 2. is there. Therefore, it can be said that the entry side of each roll is equivalent to satisfying the downhill condition.
In addition, since the material discharged horizontally from each roll goes to the pass position of the downstream roll, the material discharged from each roll does not receive a downward pressing force by the downstream roll, There is no problem that the downhill effect is canceled on the exit side. In this way, even if it is a horizontal pass line, it is equivalent to satisfying the downhill condition on both the entrance side and the exit side of the roll, and a molding equivalent to a true downhill can be performed. Thereby, the edge extension of the material in the breakdown roll region is suppressed, and therefore, the generation of the edge wave of the material is suppressed, and the cause of poor welding in the welded portion is improved.

In the embodiment of FIG. 3, the amount of eccentricity of the upper roll toward the upstream side is such that the material does not warp in the breakdown roll (that is, the material is discharged horizontally toward the pass position of the downstream roll). 3), the amount of eccentricity to the upstream side of the upper roll in the embodiment of FIG. 3 is set so that the material that has entered horizontally from the upstream side is discharged at an upward angle at the center in the material width direction. setting, i.e., it is effective to warp up some is set to occur in the material in the breakdown roll.
In this case, the material 1 that has entered the roll 2 horizontally is discharged slightly upward from the roll 2 (that is, discharged so that the material slightly warps in the roll 2). It is discharged so as to enter slightly upward from the horizontal with respect to the pass position. Then, the material discharged from the roll enters the downstream roll horizontally while being slightly pushed down by the downstream roll. However, if the push is slightly reduced, the material remains downstream while maintaining a substantially upward tendency. Enter the side roll.
If the material passes through the rolls of each stand with substantially large warping, there is a risk that a compressive force will act on the edge part and buckle will occur at the edge part, resulting in an edge wave. Is slightly lowered, and a slight tensile force acts on the edge portion of the material between the roll and the downstream roll, and the tensile force is applied to the edge between the roll and the downstream roll. It acts to prevent buckling, that is, edge waves, from occurring in the part. That is, it is effective for preventing the generation of edge waves in the breakdown roll region.

1 is a pass line design in which the cross-sectional center of the molding material gradually decreases, and the method in FIG. 3 is a pass line design in which the cross-sectional center of the molding material gradually increases, but the molding material cross-sectional center is constant. It is effective to balance the whole. Therefore, an intermediate method between the method of FIG. 1 and the method of FIG. 3 can be considered.
FIG. 4 shows an embodiment of an electric sewing tube manufacturing apparatus to which the invention of claim 4 is applied , and is a diagram for explaining a pass line design for breakdown forming from the inlet guide roll 13 to the fin pass roll. . This pass line design is a pass line design by an intermediate method between the method of FIG. 1 and the method of FIG. That is, the inlet guide roll 13 FPR # pass line L ₃ of breakdown molding leading to 1 from set downward slope, and of the upper roll 2a on the upstream side with respect to each under the roll 2b each break down rolls 2 The eccentric amount δ is set so that the material entering at a downward angle from the upstream side at the central portion in the material width direction is discharged at the same downward discharge angle as the entrance angle, that is, the breakdown roll. warp material is set so as not to occur in 2.

An example of a specific method for setting as described above will be described.
The overall pass line design is based on keeping the cross-sectional center of the molding material constant, and the pass line height is determined upstream from the FPR # 1 stand as the origin. In particular,
(1) Temporarily arrange each stand in the breakdown roll region so as to be downhill by the method of FIG. 1 (the downhill reference amount by the methods (1) to (7) described in the specific example in the case of FIG. 1). Decide).
(2) The upper roll eccentricity d based on the methods (1) and (2) described in the specific example in the case of FIG. 3 so that the material is not warped in the breakdown roll 2 in all the breakdown rolls. the ₁ to d ₃ calculated, the amount of eccentricity δ ₁ ~δ ₃ of Figure 1 which has been corrected by the amount of eccentricity _d 1 to d _3, and eccentricity δ _{'1 ~δ' 3} of each stand. Here, the corrections are generally corrections such that δ ′ ₁ ≈δ ₁ −d ₁ , δ ′ ₂ ≈δ ₂ −d ₂ , and δ ′ ₃ ≈δ ₃ −d ₃ .
As a result, the entire center of the cross section of the molding material can be kept constant or can be balanced, and the effect of downhill at each stand can be further enhanced.

In the embodiment of FIG. 4, the amount of eccentricity to the upstream side of the upper roll is discharged with a downward slope toward the pass position of the downstream roll so that the material does not warp in the breakdown roll. 4), the amount of eccentricity to the upstream side of the upper roll in the embodiment of FIG.
At the center in the width direction of the material, it is set so that the material entering downward from the upstream side is discharged at a downward discharge angle smaller than the entrance angle, that is, the material is substantially slightly warped in the breakdown roll. It is also effective to set the position so as to occur, that is, set so as to be slightly higher than the pass position of the downstream roll (that is, generally as in the third embodiment relative to the second embodiment (see FIG. 3)). is there.
In this case, the same effect as the embodiment of FIG. 3 can be obtained.

  Although the product size is not described in the above description, the present invention is suitable for manufacturing a steel pipe having a small diameter, for example, a steel pipe having an outer diameter of about 50 mm or more, for example, a steel pipe having an outer diameter of 120 mm and a thickness of 1 mm, that is, t / It is also possible to manufacture a low t / D ERW steel pipe with D of 0.8%.

1 is a view for explaining an embodiment of an apparatus for manufacturing an electric resistance welded tube to which the invention of claim 1 is applied, and illustrating a pass line design from an inlet guide roll to a fin pass roll. FIG. It is the figure which showed an example of the roll hole shape of each step | level in FIG. An embodiment of the electric sewing tube manufacturing apparatus to which the invention of claim 2 is applied is a diagram for explaining a pass line design from the entrance guide roll to the fin pass roll. An embodiment of the electric sewing tube manufacturing apparatus to which the invention of claim 4 is applied is a diagram for explaining a pass line design from the entrance guide roll to the fin pass roll. It is a principal part block diagram for demonstrating one Example of the whole structure of the manufacturing apparatus of the ERW pipe to which this invention is applied. It is a figure explaining the mechanism in which an edge wave generate | occur | produces in material at the time of pipe forming. The aspect of the butt shape defect of the material in the welded portion will be described, where (A) is a case of a butt step and (B) is a case of insufficient edge portion molding. The relationship between the entry angle of the material with respect to the roll and the occurrence of warpage will be described. (A), (b), and (c) show cases of different entry angles. When the upper roll is decentered with respect to the lower roll, it explains an example of the relationship between the entry angle of the material in the roll and the occurrence of warpage, and (A) is when the upper roll is decentered upstream, (B) shows the case where the upper roll is eccentric to the downstream side. It is a figure which shows the manufacturing method of the conventional electric sewing pipe, and is a figure explaining the pass line design (conventional downhill) between the entrance guide roll and the fin pass roll.

Explanation of symbols

1 Material (metal plate or molding material)
2 Breakdown roll (BDR # 1, BDR # 2, BDR # 3)
3 Breakdown roll region 4 Fin pass roll (FPR # 1, FPR # 2)
5 Fin pass roll region 6 Squeeze roll 7 Welding machine 8 Welded part 9 Sizing roll 10 Side roll 11 Side roll region 13 Inlet guide roll δ (δ ₁ , δ ₂ , δ ₃ ) Eccentricity δ ′ ( δ ′ ₁ , δ ′ ₂ , δ ′ ₃ ) Eccentricity d (d ₁ , d ₂ , d ₃ ) with respect to the lower roll of the upper roll Eccentricity θ (θ ₁ , θ ₂ , θ ₃ ) with respect to the lower roll of the upper roll Ingress angle α of material into roll Gradients L ₁ , L ₂ , L ₃ , L pass line at the center bottom in the material width direction in the side roll region

Claims (5)

A belt-shaped metal plate is formed into a generally circular arc shape in the breakdown roll region, formed into a substantially circular shape with both edges approaching in the fin pass roll region, and subjected to outer diameter drawing processing, and then a squeeze roll and a welder In the method of manufacturing an electric resistance welded pipe where both edges are butt-welded at a welded portion provided with
In the breakdown roll area including the front and rear stands, the path line, which is the forming direction locus in the center of the material width direction, is set to be inclined downward, and the upper roll is set for each of the plurality of breakdown rolls constituting the breakdown roll area. Eccentric to the downstream side with respect to the lower roll, so that the amount of eccentricity at the central portion in the material width direction is discharged at a downward discharge angle that is smaller than the entry angle when the material entered at a downward angle from the upstream side is discharged. and method for producing a electric-resistance-welded pipe material discharge direction at each breakdown roll and sets to face the path position of the downstream side of the roll. A belt-shaped metal plate is formed into a generally circular arc shape in the breakdown roll region, formed into a substantially circular shape with both edges approaching in the fin pass roll region, and subjected to outer diameter drawing processing, and then a squeeze roll and a welder In the manufacturing method of the electric resistance welded pipe where both edges are butt-welded in a welded portion provided with
In the breakdown roll area including the front and rear stands, the path line that is the forming direction locus in the center of the material width direction is set horizontally, and the upper roll is lowered for all of the plurality of breakdown rolls constituting the breakdown roll area. An ERW pipe characterized in that it is eccentric to the upstream side with respect to the roll, and the amount of eccentricity is set so that the material that has entered horizontally from the upstream side is discharged horizontally at the center in the material width direction . Manufacturing method . A belt-shaped metal plate is formed into a generally circular arc shape in the breakdown roll region, formed into a substantially circular shape with both edges approaching in the fin pass roll region, and subjected to outer diameter drawing processing, and then a squeeze roll and a welder In the manufacturing method of the electric resistance welded pipe where both edges are butt-welded in a welded portion provided with
In the breakdown roll area including the front and rear stands, the path line that is the forming direction locus in the center of the material width direction is set horizontally, and the upper roll is lowered for all of the plurality of breakdown rolls constituting the breakdown roll area. It causes eccentrically on the upstream side of the rolls, the eccentricity, in the material widthwise central portion, and sets so that the material entering horizontally from the upstream side is discharged in an upward angle ERW A method of manufacturing a tube. A belt-shaped metal plate is formed into a generally circular arc shape in the breakdown roll region, formed into a substantially circular shape with both edges approaching in the fin pass roll region, and subjected to outer diameter drawing processing, and then a squeeze roll and a welder In the method of manufacturing an electric resistance welded pipe where both edges are butt-welded at a welded portion provided with
In the breakdown roll area including the front and rear stands, the path line, which is the forming direction locus in the center of the material width direction, is set to be inclined downward, and the upper roll is set for each of the plurality of breakdown rolls constituting the breakdown roll area. Eccentricity to the upstream with respect to the lower roll, and the amount of eccentricity is set so that the material that has entered at a downward angle from the upstream side is discharged at the same downward discharge angle as the entry angle at the center in the material width direction A method for manufacturing an electric resistance welded tube. A belt-shaped metal plate is formed into a generally circular arc shape in the breakdown roll region, formed into a substantially circular shape with both edges approaching in the fin pass roll region, and subjected to outer diameter drawing processing, and then a squeeze roll and a welder In an electric welded tube manufacturing apparatus that butt welds both edges at a welded portion with
In the breakdown roll area including the front and rear stands, the path line, which is the forming direction locus in the center of the material width direction, is set to be inclined downward, and the upper roll is set for each of the plurality of breakdown rolls constituting the breakdown roll area. Eccentricity is made upstream with respect to the lower roll, and the amount of eccentricity is set so that the material that has entered downward from the upstream side at the center in the material width direction is discharged at a downward discharge angle that is smaller than the entry angle. A method for manufacturing an electric resistance welded tube.

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