JP2003164918A - Method and apparatus for bending work of metal pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for bending work which controls so as to minimize flattening induced to a metal pipe as much as possible. <P>SOLUTION: In the method to perform continuous bending work moving a heated zone 6 continuously to the pipe length direction, while a part of the metal pipe 1 is heated into the heated zone 6 by a heating means 5 and a bending moment to the heated zone 6 with a bending arm 2 is applied to cause a bend deformation, a dimension control means 20 is arranged just ahead of the heated zone 6, which prevents the pipe body from expanding in the direction vertical to a bending plain (NN direction) and flattening, so that the flattening is controlled by the bending work preventing the heated zone from expanding to the NN direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and apparatus for bending a metal pipe such as a steel pipe.

[0002]

2. Description of the Related Art Conventionally, as a method and apparatus for bending a metal tube, as shown in FIG. 10 (a), a tip of a metal tube 1 to be bent is formed into a bending arm 2 capable of turning around a fulcrum O. It is grasped by the attached grasping means, that is, the arm side clamp 3, and the rear end thereof is grasped by the grasping means, that is, the tail side clamp 4 connected to the pipe moving means (not shown) for moving the metal pipe in the pipe longitudinal direction. A heating means 5 such as an induction coil capable of forming a heating part 6 by heating a short section in the longitudinal direction of the tube so as to surround the tube 1 is arranged, and the heating means 5 heats the metal tube to In the state where 6 is formed, the metal pipe 1 is continuously advanced in the pipe longitudinal direction while the trajectory is regulated by the tail side clamp 4, so that the metal pipe 1 is bent to the bending arm 2 as shown in FIG. Bending moment is applied to bend the heating part 6 Is, the heating means 5 to the portion of the immediately
It is known that the cooling water 7 is sprayed to cool the pipe, and the heating portion 6 is continuously moved relative to the longitudinal direction of the pipe to continuously bend the pipe. In the figure, 8 is a guide roller. Usually, the swivel arm 2 is arranged so as to swivel in a horizontal plane, and thus the bending plane (the plane including the central axis of the bent metal tube) is horizontal. Hereinafter, for convenience of explanation, as shown in FIGS. 10B and 10C, the direction along the bending plane in the plane orthogonal to the central axis of the bent portion of the metal tube is the CT direction, and the direction orthogonal thereto is NN. Direction.

As shown in FIG. 11, each of the clamps 3 and 4 used conventionally has a fixed support member 11 having an arcuate support surface 11a for supporting the inner circumference side of the bend of the metal tube 1.
And a swivel support member 12 having an arcuate support surface 12a that is pivotally held at its upper end around a fulcrum P and that supports the bending outer peripheral side of the metal pipe 1, and the metal pipe 1 is tightened and fixed. A metal cylinder 1 is provided with a hydraulic cylinder 13 for pressing the swivel support member 12 toward the fixed support member 11.
Was pressed and fixed in the CT direction. The radius of the arcuate support surfaces 11a and 12a is slightly larger than the radius of the outer surface of the metal tube 1 so that the metal tube 1 can be held well even if there is some error in the outer diameter of the metal tube 1. It is set. Therefore, the metal tube 1 pressed in the CT direction by the support surfaces 11a and 12a can be slightly enlarged in the NN direction to be flat. Here, the metal tube 1 is attached to the support surface 1
The structure in which the 1a and 12a are pressed and held in the CT direction has a flat shape in which the pipe end of the metal pipe 1 after bending (the part held by the clamps 3 and 4) is enlarged in the CT direction as described later. This is because the clamps 3 and 4 are trying to suppress it.

[0004]

In the bending method as shown in FIG. 10, due to the action of the bending moment, a force is applied to the metal tube 1 at the time of bending to reduce the CT dimension of the tube. However, there is a tendency for flattening, and in particular, when the wall thickness of the metal tube is thin, or when the ratio of the bending radius to the tube diameter is small, the flattening becomes large and cannot be ignored. Moreover, the flattening of the metal tube occurs not only in the bent region but also in the straight pipe portions on both sides thereof, and the flattening direction is different. That is, as shown in an exaggerated manner in FIG. 12, when the cross-sectional shape of the metal pipe after bending is viewed, the tubular body 1a in the bending region between the bending start point s and the bending end point e extends in the NN direction. It has an enlarged flat shape (elliptical shape with a major axis in the NN direction), but in the straight pipe parts before and after the bending region, the pipes at positions b and c that are apart from the bending region by 1 to 2 times the pipe diameter. The bodies 1b and 1c are
On the contrary, it had a flat shape enlarged in the CT direction (elliptical shape with the major axis in the CT direction). Conventionally, in order to suppress the flattening that occurs in the straight pipe portion so as to expand in the CT direction, the clamps 3, 4 are
Although the tubular body was pressed in the CT direction so as not to expand, the flattening could not be prevented. When these flattenings occur, the external dimensions deviate from the desired dimensions, pipe end misalignment,
This may lead to problems such as reduced strength and increased resistance to passing fluid. Therefore, the allowable flatness is usually set, and bending is performed so that the allowable flatness is equal to or lower than the allowable flatness. However, depending on the bending conditions, it may not be possible to suppress the flatness ratio below the allowable flatness. In that case, there is a problem that the flattening work is performed after the bending work is completed, resulting in a high cost. .

The present invention has been made in view of the above problems, and provides a method and apparatus for bending a metal pipe capable of reducing the flattening of the metal pipe caused by bending to a negligible level. The purpose is to do.

[0006]

Means for Solving the Problems As a result of intensive studies by the inventors of the present invention for suppressing flattening of a metal tube caused by bending, a portion of the metal tube immediately before a heating portion in which bending deformation occurs. Alternatively, the bending process can be performed while restricting the portion gripped by the clamps before and after the region to be bent and deformed so as to prevent the tubular body from expanding in the direction orthogonal to the bending plane and flattening. The inventors have found that flattening can be suppressed, and have completed the present invention. That is, the present invention, the operation of bending and deforming the heating portion by heating a short section in the longitudinal direction of the pipe while applying a bending moment to the metal pipe,
When performing bending by sequentially applying the heating means in the longitudinal direction of the pipe to sequentially apply the bending means in the longitudinal direction of the pipe, the pipe body is bent immediately before the portion where the metal pipe is bent and deformed. In order to arrange the dimension regulating means for preventing expansion and flattening in the direction orthogonal to the plane and to perform bending while regulating the tube body by the dimension regulating means, and / or to advance bending deformation Either one or both of the gripping means for gripping the tubular body at the front end side and the rear end side of the metal pipe is configured to prevent the tubular body from expanding and flattening in a direction orthogonal to the bending plane, Bending is performed while preventing the tube body from expanding and flattening in the direction orthogonal to the bending plane by the gripping means. With this configuration, flattening caused by bending is suppressed to a small level. You can

Here, the reason why the flattening of the metal tube is suppressed is considered as follows. When performing the bending process by the conventional method, as shown in FIG. 13, while the bending process of the metal tube 1 is in progress,
A bending moment acts on the heating portion 6 heated to the red hot state, bending deformation occurs in the heating portion 6, and the cooling water 7 is sprayed and cooled to the portion immediately after the deformation to fix the bending deformation. Around this bending deformation progressing portion, a force for flattening the tubular body acts on the heating portion 6 as a reaction of the bending moment, so flattening occurs due to the bending deformation, and the portion of the heating portion 6 where the bending deformation occurs The tube body 1f has a flat shape that is enlarged in the NN direction. At this time, since the straight pipe portion before being bent and the straight pipe portion on the tip side are not heated, they have high rigidity, and it is considered that these straight pipe portions are held in a perfect circle. It was being done. However, as confirmed by the present inventors, the flattening force acting on the heating unit 6 is considerably transmitted not only to the heating unit 6 but also to the region before and after the heating unit 6.
As a result, even at positions g and h on the straight pipe part, the pipe body 1g,
1h has a flat shape enlarged in the NN direction, and moreover, since the clamps 3 and 4 hold the straight pipe portion while pressing it in the CT direction, this also promotes the flat shape enlarged in the NN direction. ing. In this state, the heating portion 6 was bent and deformed, so that the bending region was considerably flattened. Also, in the straight pipe part outside the bending region,
The shape was balanced with the flattening of the bending region, and the shape was flattened in the CT direction. On the other hand, in the present invention, the portion immediately before the heating portion 6 or the portion gripped by the clamps 3 and 4 is configured to prevent the tubular body from expanding and flattening in the direction orthogonal to the bending plane. As a result, these portions are held in a perfect circle shape or a flat shape slightly enlarged in the CT direction during bending, which suppresses flattening of the heating portion 6 during bending deformation, and as a result, bending is performed. The flattening enlarged in the NN direction in the region is extremely reduced. Further, as a result of suppressing flattening in the bending region, flattening in the straight pipe portion is also suppressed, and flattening of the entire metal pipe after bending is reduced. Thus, flattening prevention is achieved by the present invention.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A bending method according to an embodiment of the present invention is a method of heating a metal tube by bending a heating section by heating a short section in the longitudinal direction of the tube while applying a bending moment. When performing bending while sequentially applying the means in the pipe longitudinal direction by successively moving the means in the pipe longitudinal direction, immediately before the portion where the bending deformation of the metal pipe occurs,
A feature is that a dimension regulating means for preventing the tubular body from expanding and flattening in a direction orthogonal to a bending plane (NN direction) is arranged, and bending is performed while regulating the tubular body by the dimension regulating means. To do. In this way, by preventing the tubular body immediately before the heating portion in which the bending deformation has occurred from expanding and flattening in the NN direction, the heating portion in which the bending deformation has occurred expands in the NN direction. Flattening can be prevented, and flattening that occurs in the metal tube after bending can be reduced.

In the bending method according to another embodiment of the present invention, any one of the holding means for holding the tubular body on the front end side and the rear end side of the metal pipe in order to further promote bending deformation in the above embodiment. One or both of them has a structure for preventing the tube from expanding and flattening in the direction orthogonal to the bending plane, and the gripping means expands and flattening the tube in the direction orthogonal to the bending plane. It is characterized in that the bending process is performed while blocking. With this configuration, it is possible to better prevent the heating portion that has undergone bending deformation from expanding and flattening in the NN direction, and it is possible to reduce flattening that occurs in the metal tube after the bending process is completed.

In a bending method according to still another embodiment of the present invention, the operation of bending and deforming the heating portion by heating a short section in the longitudinal direction of the metal tube while applying a bending moment to the metal tube is performed. When performing relative bending in the longitudinal direction of the pipe by successively moving relative to the longitudinal direction of the pipe, the pipe body is gripped by the front end side and the rear end side of the metal pipe in order to promote bending deformation. One or both of the gripping means has a structure for preventing the tube from expanding and flattening in the direction orthogonal to the bending plane, and the gripping means expands the tube in the direction orthogonal to the bending plane to flatten it. It is characterized in that the bending process is performed while preventing the change. With this configuration as well, it is possible to prevent the heating portion that has undergone bending deformation from expanding and flattening in the NN direction, and it is possible to reduce flattening that occurs in the metal tube after the bending process is completed.

In the bending method according to still another embodiment of the present invention, in each of the above-described embodiments, the bending body is expanded in the direction orthogonal to the bending plane to the bent pipe during the bending operation. The present invention is characterized in that the same type of size regulation / correction means for preventing or correcting the flattening is attached, and the bending process is continued in that state. With this configuration, it is possible to better prevent the heating portion that has undergone bending deformation from expanding and flattening in the NN direction, and it is possible to reduce flattening that occurs in the metal tube after the bending process is completed.

In the bending method according to still another embodiment of the present invention, in each of the above-described embodiments, immediately after the portion of the metal pipe where the bending deformation occurs, the tubular body is moved in a direction orthogonal to the bending plane. It is characterized in that a stationary type size regulation / correction means for preventing or straightening the expanding flattening is arranged, and bending is performed while the pipe body is regulated by the size regulation / correction means. With this configuration, the heating portion that is undergoing bending deformation is N
It is possible to better prevent flattening by expanding in the N direction,
The flattening that occurs in the metal tube after the bending process can be reduced.

A bending apparatus according to an embodiment of the present invention comprises a first holding means and a second holding means for holding a pipe body before and after a region of a metal pipe to be bent, and a longitudinal direction of the metal pipe. The heating means for heating a short section of the direction, the moving means for continuously moving the heating means relative to each other in the longitudinal direction of the tube, and the metal tube for bending the metal tube into a predetermined bending plane. It is arranged on the side of the second gripping means adjacent to the moment applying means for applying a bending moment via the gripping means, and on the side of the second gripping means, so that the tubular body expands in a direction orthogonal to the bending plane and is flattened. The present invention is characterized in that it is provided with a dimension controlling means for preventing the bending, and with this configuration, the tube just before the heating section is bent by the dimension controlling means while being regulated so as not to be flattened by expanding in the NN direction. Yes, bending deformation And it has a flattening of the heating unit to prevent a flattening occurring in the metal pipe after the processing end bending can be reduced.

In a bending apparatus according to another embodiment of the present invention, the dimension regulating means in the bending apparatus according to the above-described embodiment is arranged in parallel with the bending plane and in a relationship of sandwiching the tubular body. This is a configuration including a pair of flattening prevention rollers, and with this configuration, the tube body can be regulated so as not to be expanded and flattened in the NN direction.

In a bending apparatus according to still another embodiment of the present invention, the tubular body is provided with one or both of the first holding means and the second holding means in the bending apparatus according to the above-mentioned embodiment. The tube body is structured so as to hold the tube body in such a manner as to prevent the tube body from expanding and flattening in the direction orthogonal to the bending plane, and with this configuration, the tube body is bent by the first and / or second gripping means. Bending can be performed while preventing expansion and flattening in the direction orthogonal to the plane, and it is better possible to prevent expansion and flattening in the NN direction of the heating portion that has undergone bending deformation. As a result, flattening of the metal pipe after bending can be reduced.

A bending apparatus according to still another embodiment of the present invention comprises a first holding means and a second holding means for respectively holding a pipe body before and after a region of a metal pipe to be bent,
Heating means for heating a short section of the metal tube in the longitudinal direction,
A moving means for continuously moving the heating means relative to each other in the longitudinal direction of the pipe, and a moment imparting a bending moment to the metal pipe through the first gripping means so that the metal pipe is bent and deformed within a predetermined bending plane. Means, one or both of the first gripping means and the second gripping means,
The pipe body is structured to hold the pipe body in a mode that prevents the pipe body from expanding and flattening in a direction orthogonal to the bending plane, and by this configuration, the first and / or second holding means. It is possible to perform bending while preventing the tubular body from expanding and flattening in the direction orthogonal to the bending plane, and to prevent the heating portion that has undergone bending deformation from expanding and flattening in the NN direction. It is possible to prevent the flattening of the metal tube after the bending process.

In still another embodiment of the present invention, in the apparatus according to the above-mentioned embodiment, either one or both of the first gripping means and the second gripping means has a bending inner circumference side or a bending outer circumference side of the tubular body. A fixed support member that supports the side, and the fixed support member, which is rotatably held at two points separated in a direction orthogonal to the bending plane, respectively, and has a large area other than a region of the tubular body supported by the first support member. A first swivel support member and a second swivel support member, which support the partial region in approximately two halves, and the tube body is held by the fixed support member, the first swivel support member, and the second swivel support member, The first swivel support member and the second swivel support member are configured to have a pressing unit that presses them in directions toward each other. With this configuration, the first gripping means and / or the second gripping means can firmly grip the tubular body in a state of being close to a perfect circle, and the heating portion in which bending deformation has occurred expands in the NN direction and becomes flat. Can be prevented.

Still another embodiment of the present invention is the device according to the above-mentioned embodiment, further, in the direction adjacent to the heating means on the side of the first gripping means, the tube body is enlarged in a direction orthogonal to the bending plane. The configuration is such that a stationary size regulation / correction means for preventing or correcting such flattening is provided. With this configuration, it is possible to perform bending processing while restricting the tubular body immediately after the heating unit by the stationary size regulation / correction means so as not to expand and flatten in the NN direction. It is possible to prevent the flattening of the portion more favorably, and further reduce the flattening that occurs in the metal pipe after the bending process is completed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view showing a metal pipe bending apparatus according to a preferred embodiment of the present invention,
The same parts as those of the conventional example shown in FIG. 10 are designated by the same reference numerals. In FIG. 1, 1 is a metal tube to be bent. The metal tube 1 is arbitrary as long as it can be hot-bent, and is a steel tube in many cases. The bending apparatus according to this embodiment includes a first gripping means (that is, an arm clamp on the tip side) 15 and a second gripping means (that is, a rear end) for gripping a tubular body before and after a region of the metal tube 1 to be bent. (End tail clamp) 16, a short section in the longitudinal direction of the metal tube 1 to be a heating section 6 and a heating means 5 such as an induction coil that blows out cooling water 7 and the heating means 5 A moving means (not shown) for continuously making relative movement in the direction.
In this embodiment, a tube moving means for moving the metal tube 1 in the tube longitudinal direction via the second gripping means 16 is used),
Adjacent to the heating means 5 and the moment applying means for applying a bending moment to the metal tube 1 through the first gripping means 15 so that the metal tube 1 is bent and deformed in a predetermined bending plane, that is, the heating arm 5. It is arranged on the second gripping means 16 side,
Dimension control means 20 for preventing the tubular body from expanding and flattening in the direction orthogonal to the bending plane, and arranged in the vicinity thereof,
A guide roller 8 that regulates the traveling path of the metal tube 1, and FIG.
The same size-regulating / correcting means 22 shown in FIG.

First gripping means 15 and second gripping means 16
Has a structure of holding the tube body in a mode that prevents the tube body from expanding and flattening in a direction orthogonal to the bending plane, and specifically, as shown in FIG. Of the fixed support member 24 having an arcuate support surface 24a for supporting the inner side of the bend or the outer side of the bend, and the fixed support member 24 can be respectively swung at two points Q and R separated in a direction orthogonal to the bending plane. A first swivel support member 25 provided with arcuate support surfaces 25a, 26a for holding and holding a large portion of the tubular body 1 other than the region supported by the first support member 24 in a substantially bisected manner.
And the second swivel support member 26 and the tubular body 1 for the fixed support member 2
4 and a pressing means 27 such as a hydraulic cylinder that presses the first turning support member 25 and the second turning support member 26 toward each other so as to be held by the first turning support member 25 and the second turning support member 26. is doing. With this configuration, the pipe body 1 is pressed and grasped by the first turning support member 25 and the second turning support member 26 in the NN direction, and therefore, the pipe body is placed on the pipe body 1 when the bending process is performed. Even if a force that expands in the direction is applied, expansion of the tubular body in the NN direction can be prevented. Moreover, since the tubular body is not only gripped by the first swivel support member 25 and the second swivel support member 26 but also by the fixed support member 24, three outer peripheral surfaces of the tubular body 1 are eventually obtained. Arcuate support surface 24
Since it is supported by a, 25a, and 26a, the tube body 1 can be firmly gripped in a state close to a perfect circle. The structures of the first gripping means 15 and the second gripping means 16 are as follows.
The present invention is not limited to the one shown in FIG. 2, but can be changed as appropriate. For example, the conventional clamp 3 shown in FIG. 11 is arranged with its mounting direction rotated by 90 degrees, and is gripped in a form of pressing the tubular body in the NN direction. It may be configured to.

The dimension control means 20 prevents the tubular body from expanding and flattening in the direction (NN direction) orthogonal to the bending plane, and as shown in FIG.
A pair of flattening prevention rollers 3 held by the frame 30
1, 32 and pressing means 33 such as a hydraulic cylinder for pressing the one flat prevention roller 32 toward the other flat prevention roller 31. Here, the pair of flattening prevention rollers 31 and 32 are arranged parallel to the bending plane and sandwiching the tube body 1. By pressing the flattening prevention roller 32 against the tube body 1 by the pressing means 33, By the flattening prevention rollers 31 and 32, the tube body 1 can be regulated so as not to expand in the NN direction and flatten. In this embodiment, the force for pressing the flattening prevention roller 32 against the tube body 1 by the pressing means 33 prevents the tube body 1 from expanding and flattening in the NN direction. Using a screw mechanism or the like capable of adjusting the position of the flattening prevention roller 32, the position of the flattening prevention roller 32 is set to a position where the displacement of the tube body 1 expanding in the NN direction and flattening can be restricted by the screw mechanism or the like. It may be configured to be positioned and fixed at that position.

In FIG. 4, the dimension control / correction means 22 of the same type is attached to the tube body 1 after bending deformation so as to run along with the tube body 1 during the bending operation so that the tube body is in a bending plane. It is intended to prevent or correct the flattening that expands in a direction orthogonal to each other, and has a substantially C-shaped frame 41, and a tubular body support member 4 provided at both ends of the frame 41 so as to face each other.
It is equipped with 2, 43, etc. One tube support 42 is fixedly provided on the frame 41, and the other tube support 43 is rotatably held on the tip of a screw shaft 44 screwed into the frame 41. A handle 45 for operation is attached to the other end of the screw shaft 44. With this structure, the dimension regulation / correction means 22 is arranged with respect to the tubular body 1 so that the tubular body supporters 42 and 43 contact both outer surfaces in the NN direction, and the handle 45 is operated to screw in the screw shaft 44. By moving it, the tube supporter 42, 43
It can be pressed in the N direction, and if
If a flattened shape that has expanded in the direction has occurred, the flattened shape can be corrected and held in a corrected state. A plurality of this size regulation / correction means 22 are prepared.

Next, a bending method using the bending apparatus having the above structure will be described. Figure 1 shows a metal tube 1 to be bent
And the pressing means 3 of the size regulating means 20 as shown in FIG.
3 is operated to keep the metal tube 1 pressed in the NN direction by the flattening prevention rollers 31 and 32. In this state, heating by the heating means 5 and injection of the cooling water 7 are started, and then
The forward movement of the second gripping means 16 holding the rear end of the metal tube 1 is started. As a result, as shown in FIG. 5, the metal tube 1 advances in the tube longitudinal direction and the bending arm 2 pivots to apply a bending moment to the metal tube 1 to bend and deform the heating portion 6. At this time, a force is applied to the tube body 1f at the position f of the heating unit 6 in a direction to reduce the tube body in the CT direction, and accordingly, the tube body 1f tends to expand in the NN direction to be flattened. However, the tube body 1g at the position g immediately before the heating portion 6 is constrained by the flattening prevention rollers 31 and 32 so as not to expand in the NN direction, and the tube body at the position h of the straight tube portion at the tip of the metal tube. 1h is also restrained by the first gripping means 15 so as not to expand in the NN direction.
g and 1h do not expand and flatten in the NN direction,
It maintains a nearly perfect circle. And these tubes 1g,
1 h prevents the tube body 1 f of the heating unit 6 from being flattened, and the heating unit 6 is bent and deformed without being flattened.

Continuing the bending operation, FIG. 6 (a)
As shown in, when the first gripping means 15 held by the bending arm 2 moves away from the heating part 6, the effect of restraining the heating part 6 by the first gripping means 15 in the NN direction is weakened. Therefore, a slight flattening occurs during bending deformation.
Therefore, while continuing the bending operation, the feeding type dimension regulating / correcting means 22 is attached to the portion immediately after the bending deformation, and the screw shaft 44 is tightened as shown in FIG. The flatness that had occurred on the body was corrected, and the tubular body was restrained so as not to expand in the NN direction. As a result, the heating unit 6
The binding action in the NN direction with respect to is increased, and the bending deformation proceeds without flattening the heating portion 6. After that, the bending operation is continued, and another dimensional regulation / correction means 22 is attached at an appropriate timing. And FIG. 6 (b)
As shown in FIG. 5, after performing the bending process on the desired bending region, the advance of the metal tube 1 is stopped and the bending process is completed.
As described above, in the above-described embodiment, since bending is performed with the expansion in the NN direction in the heating portion 6 being restrained as much as possible, the obtained bent pipe has a very small flatness in the bending region. Therefore, the flatness generated in the straight pipe portion is also extremely small.

In the above-described embodiment, the tube body which is attached to the tube body 1 serves as the dimension control / correction means 22 for preventing or correcting the flattening of the tube body after bending and deformation which expands in the direction orthogonal to the bending plane. Although the same type is used, which is run together, it is also possible to use a stationary type size regulation / correction means instead of or in combination with this. FIG. 7 shows an embodiment in which a stationary type size regulation / correction means 51 is used, and the size regulation / correction means 51 is the heating means 5.
Is disposed in the vicinity of and on the first gripping means 15 side. As shown in FIG. 8, the stationary size regulation / correction means 51 includes a frame 52 having an open side, a pair of tube support rollers 53 arranged above and below the tube 1, and a tube support. Roller holders 54 that respectively hold the rollers 53 and the roller holders 54 in the vertical direction (NN
A guide rod 55 and a bearing 56 for movably holding the roller holder 54, and a pressing means 57 such as a hydraulic cylinder and a screw mechanism for moving the roller holder 54 in the vertical direction (NN direction). With this configuration, the first gripping means 15 and the bending arm 2 holding the tubular body 1 can be passed by passing the tubular body supporting rollers 53, 53, which are arranged above and below, largely open in the vertical direction. After that, by pressing the upper and lower tubular body supporting rollers 53, 53 against the tubular body 1, the tubular body 1 is pressed in the NN direction, and the flattening of the bent and deformed tubular body 1 in the NN direction is prevented or corrected. be able to.

Bending using the stationary type size regulation / correction means 51 is performed as follows. In FIG. 7A, at the start of the bending process, the tube body supporting roller 53 of the dimension regulating / correcting means 51 is largely opened vertically so as not to interfere with the turning of the bending arm 2. In this state, the bending process is started, and after the bending arm 2 has swung to a position where it does not interfere with the dimension regulating / correcting means 51, the pressing means 57 of the dimension regulating / correcting means 51 is operated to move up and down as shown in FIG. The tubular body supporting rollers 53, 53 are pressed against the tubular body 1 and restrained so that the tubular body 1 after bending deformation does not flatten out to expand in the NN direction. If flattening has occurred, correct it. After that, the bending process is continued in a state in which the tube body 1 is restrained by the tube body supporting rollers 53 so as not to cause the flattening of the tube body 1 in the NN direction. Thus, in this embodiment, the heating portion 6 is constrained by the dimension regulating means 20 and the dimension regulating / correcting means 51 before and after the heating portion 6 so as not to cause flattening that expands in the NN direction, and flattening hardly occurs. Bending can be performed with. If necessary, as shown in FIG. 7B, the dimension regulation / correction means 5
The above-mentioned feed type dimensional regulation / correction means 22 may be attached to the pipe body which has passed through 1, so that flattening can be further prevented.

[0027]

EXAMPLE A SGP 12B (nominal outer diameter 318.5 mm) × 1650 mm was prepared as a sample metal tube 1, and a bending radius R = 4 was set for this metal tube with the device configuration shown below.
77 mm, feed rate 1.2 mm / sec, temperature 980-10
Bending was performed at 10 ° C to obtain a bent tube having a shape shown in Fig. 9. The flatness was measured at points A, B, C, D and E (the unit of numerical values in the figure is mm) of this curved pipe. The results are shown in Table 1. The flatness is calculated by "(outer diameter in NN direction-outer diameter in CT direction) / average outer diameter of raw pipe". If this value is positive, it indicates a flattened shape expanded in NN direction. In the case of negative, a flat shape enlarged in the CT direction is shown.

[Embodiment 1] Using the apparatus shown in FIGS. 1 to 4, the dimension regulating / correcting means 22 has bending angles of 30 degrees and 60 degrees.
It was installed at the degree position. [Embodiment 2] In the apparatus shown in FIGS.
The first and second gripping means 15 and 16 for holding the front and rear of the
Instead of the conventional clamp shown in FIG. 11, the dimension regulating / correcting means 22 was attached at the bending angle of 30 ° and 60 °. [Embodiment 3] In the apparatus shown in FIGS.
The first and second gripping means 15 and 16 for holding the front and rear of the
Changed to the conventional clamp shown in FIG.
The corrective means 22 was not used. [Embodiment 4] In the apparatus shown in FIGS. 1 to 4, the size regulating means 20 was removed and the size regulating / correcting means 22 was not used. [Comparative Example 1] The conventional apparatus shown in FIGS. 10 and 11 was used, and the dimension regulation / correction means 22 was not used.

[0029]

[Table 1]

As is clear from the results shown in Table 1, in Examples 1 to 4 of the present invention, the flatness was significantly lower than that of Comparative Example 1, and in particular, flatness was almost generated in Example 1. Didn't.

[0031]

As described above, according to the method and apparatus of the present invention, it is possible to prevent the heating portion, which has undergone bending deformation, from expanding in the NN direction when bending is performed. To prevent flattening when bending and deforming,
The flatness that occurs in the bending region can be reduced, and the flatness that occurs in the bending region also affects the straight pipes on both sides to flatten it.However, since the flatness of the bending region is small, The flatness that occurs in the part can be made extremely small,
In the end, it is possible to produce bent tubes with a very small flatness. Therefore, there is no need for post-treatment such as flattening of the bent pipe after bending, which has the effect of reducing the manufacturing cost of the bent pipe.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a bending apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a schematic front view of a first gripping means used in the bending apparatus shown in FIG.

FIG. 3 is a schematic front view of a dimension control unit used in the bending apparatus shown in FIG.

FIG. 4 is a schematic front view of the dimension regulation / correction means used in the bending apparatus shown in FIG.

5 is a schematic plan view showing an initial state when bending is performed by the bending apparatus shown in FIG. 1 and a schematic cross-sectional view of the tubular body at that time.

6 (a) and 6 (b) are schematic plan views showing intermediate and final states when performing bending with the bending apparatus shown in FIG.

7 (a) and 7 (b) are schematic plan views showing intermediate and final states when performing bending with a bending apparatus according to another embodiment of the present invention.

8 is a schematic front view of the dimension regulation / correction means used in the bending apparatus shown in FIG.

FIG. 9 is a schematic plan view showing a bent pipe after bending and its oblateness measurement position.

10A is a schematic plan view of a conventional bending apparatus, FIG. 10B is a schematic plan view showing a state in which bending is performed by the bending apparatus, and FIG. 10C is a bending region of a metal tube. Schematic cross section of

11 is a schematic front view of a clamp used in the conventional bending apparatus shown in FIG.

FIG. 12 is a schematic plan view of a bent pipe processed by the conventional bending apparatus shown in FIG. 10 and a schematic cross-sectional view exaggerating a tube body section of each part of the bent pipe.

13 is a schematic plan view showing an initial state when bending is performed by the conventional bending apparatus shown in FIG. 10 and a schematic cross-sectional view exaggerating a tubular body section of each part of the metal tube.

[Explanation of symbols]

1 metal tube 2 Moment giving means (bending arm) 5 heating means 6 heating unit 7 cooling water 15 First gripping means 16 Second gripping means 20 Dimension control means 21 Guide roller 22 Simultaneous size control and correction means 24 Fixed support member 25 First swivel support member 26 Second swivel support member 27 Pressing means 30 frames 31, 32 Flat prevention roller 33 Pressing means 41 frames 42,43 Tube support 44 screw shaft 51 Stationary size regulation and correction means 52 frames 53 Tube support roller 57 Pressing means

Claims (11)

[Claims] 1. An operation of heating a short section in a longitudinal direction of a metal tube while applying a bending moment to the metal tube to bend and deform the heating section is to continuously relatively move the heating means in the longitudinal direction of the tube. At the time of performing bending by sequentially applying in the pipe longitudinal direction, the pipe body is prevented from expanding and flattening in the direction orthogonal to the bending plane immediately before the portion where the bending deformation of the metal pipe occurs. A method for bending a metal tube, comprising: arranging a dimension regulating means, and performing bending while regulating the tube body by the dimension regulating means. 2. The bending method according to claim 1, wherein either one or both of the holding means for holding the tube body at the front end side and the rear end side of the metal tube for advancing bending deformation is connected to the tube body. Has a structure for preventing expansion and flattening in the direction orthogonal to the bending plane, and performing bending while preventing the tubular body from expanding and flattening in the direction orthogonal to the bending plane by the gripping means. A method for bending a metal tube, which is characterized in that 3. The operation of bending and deforming the heating portion by heating a short section of the metal tube in the longitudinal direction while applying a bending moment to the metal tube is performed by continuously moving the heating means in the tube longitudinal direction. When performing bending by sequentially applying in the longitudinal direction of the pipe, either one or both of the holding means for holding the pipe at the front end side and the rear end side of the metal pipe in order to promote bending deformation, the pipe body is A structure that prevents expansion and flattening in the direction orthogonal to the bending plane is performed, and bending is performed while preventing the tube body from expanding and flattening in the direction orthogonal to the bending plane by the gripping means. A method for bending a metal tube, characterized by: 4. The bending method according to any one of claims 1 to 3, wherein during the bending operation, the flattened tubular body expands in a direction orthogonal to the bending plane of the tubular body after bending deformation. A method for bending a metal pipe, characterized in that the same size regulation / correction means for preventing or straightening is attached, and bending is continued in that state. 5. The flattening method according to any one of claims 1 to 4, wherein the tubular body expands in a direction orthogonal to a bending plane immediately after a portion of the metal tube where bending deformation occurs. A method for bending a metal pipe, comprising arranging a stationary type size regulation / straightening device for preventing or straightening the metallization, and performing bending while regulating the pipe body by the size regulation / straightening device. 6. A first gripping means and a second gripping means for gripping the tubular body before and after a region to be bent of the metal tube, and a heating means for heating a short section in the longitudinal direction of the metal tube. A moving means for continuously moving the heating means relative to each other in the longitudinal direction of the pipe, and a moment imparting a bending moment to the metal pipe through the first gripping means so as to bend and deform the metal pipe within a predetermined bending plane. And a heating means, a metal pipe provided adjacent to the heating means, on the side of the second gripping means, and a size regulating means for preventing the tube body from expanding and flattening in a direction orthogonal to the bending plane. Bending equipment. 7. The apparatus for bending a metal tube according to claim 6, wherein the dimension regulating means includes a pair of flattening prevention rollers arranged in parallel to the bending plane and in a relationship of sandwiching the tube body. 8. The tube body in a mode that prevents one or both of the first gripping means and the second gripping means from expanding and flattening in the direction orthogonal to the bending plane of the tube body. The bending apparatus for a metal tube according to claim 6 or 7, which has a gripping structure. 9. A first gripping means and a second gripping means for gripping the tubular body before and after a region to be bent of the metal pipe, and a heating means for heating a short section of the metal pipe in the longitudinal direction. A moving means for continuously moving the heating means relative to each other in the longitudinal direction of the pipe, and a moment imparting a bending moment to the metal pipe through the first gripping means so as to bend and deform the metal pipe within a predetermined bending plane. Means for gripping the tubular body in such a manner as to prevent one or both of the first gripping means and the second gripping means from expanding and flattening in the direction orthogonal to the bending plane of the tubular body. An apparatus for bending a metal tube, which is characterized by having a structure. 10. One or both of the first gripping means and the second gripping means support a fixed inner peripheral side or an outer peripheral bent side of the tubular body, and a fixed plane on the fixed supporting member. A first swivel support member, which is rotatably held at two points separated in a direction orthogonal to, and which substantially bisects most of the region of the tubular body other than the region supported by the first support member, and A direction in which the first swivel support member and the second swivel support member approach each other so that the second swivel support member and the tubular body are gripped by the fixed support member, the first swivel support member, and the second swivel support member. The bending apparatus for a metal tube according to claim 6, further comprising a pressing unit that presses the metal tube. 11. A stationary dimensional regulation which is arranged adjacent to the heating means on the side of the first gripping means and which prevents or corrects flattening of the tubular body expanding in a direction orthogonal to the bending plane. The bending apparatus for a metal pipe according to claim 6, further comprising a straightening unit.