JP4906573B2 - Metal tube bending apparatus and bending method - Google Patents

Description

  The present invention relates to a metal tube bending apparatus and bending method for performing so-called arm-rotating high-frequency bending.

The arm-rotating high-frequency bending process (see, for example, Patent Documents 1 to 12), for example, applies an annular induction heating to a steel pipe and a bending moment by a bending moment adding mechanism to sequentially bend the heating part in a moving manner. Technology. The bending moment is generated by the cooperative action of the front end side path restriction by the rotating arm and the propulsion from the rear end side by the pusher.
Pusher thrust in simple push bending without applying compression axial force is 3DR (that is, about 600 mm to 1200 mm) which is a general bending radius of a steel pipe having a nominal diameter of 200 to 400 A (outer diameter of 216.3 mm to 406.4 mm). It is about 100 kN in the case of bending with, and becomes even larger in compression bending.

The steel pipe is clamped and fixed to the pivot end side of the arm and is subjected to a path restriction by the pivot arm. At that time, a moment acts on the clamp as a reaction of applying the bending moment to the steel pipe. In other words, in order to perform a satisfactory bending process, it is necessary to clamp firmly so that the fixed state does not go wrong due to the moment.
This also applies to a case where a liner is provided on the clamp at the tip of the rotating arm to elastically deform the tube end straight portion into an elliptical shape (see, for example, Patent Document 1).

In addition, in order to make the device compact, in the device that applies thrust to the pipe body by an intermediate clamp arranged in front of the rear end of the steel pipe, a large frictional force is required in the clamp portion as a reaction force of the thrust, After all, the addition of a strong tightening force is desired.
For this reason, clamping is performed with a tightening force of 30 N / mm ² or more. Since this tightening force is around 30% of the yield strength of the steel material, the steel pipe does not yield as long as it acts evenly.

Japanese Patent Publication No. 58-38251 JP-A-8-323426 JP-A-8-323427 JP-A-6-269860 JP-A-9-57357 JP 2000-94043 A JP 2000-153111 A JP 2000-263144 A JP 2002-113523 A JP 2003-164918 A JP 2005-144469 A JP 2006-326667 A

However, uneven contact is unavoidable in the clamp portion on which a moment acts, and a rolling force that is several times greater than the tightening force may be locally applied to the uneven contact portion. For this reason, an indentation may remain in the uneven contact portion of the steel pipe from which the clamp is removed.
That is, the direction in which the clamping force of the clamp is increased to the limit of the yield strength of the steel is accompanied by a non-defective yield loss due to the occurrence of indentation or a measurement yield loss due to the introduction of a cutting allowance in anticipation of the indentation.

However, in cases with a high processing load such as stainless steel pipes with high deformation resistance, small R-bending (small radius bending), or compression bending, the clamping force can be further increased. I want to increase it.
Therefore, it is an issue to provide a bending technique provided with a clamping technique that does not cause any trouble even if the clamping force is increased to the limit of the material strength of the metal tube, such as the yield strength of the steel material.

  The metal pipe bending apparatus (Claim 1) of the present invention has been devised to solve such a problem, and is for inductively heating a short section in the longitudinal direction of a metal pipe to be bent. An inductor, a cooling mechanism for cooling the heating portion by the inductor, a rotating arm for restricting the path on the tip side of the metal tube in an arc shape, and a pusher for propelling the metal tube from the rear end side In the metal tube bending apparatus provided with a bending moment applying mechanism that sequentially bends and deforms the metal tube from one end side, the rotating arm is connected to the tip end side of the metal tube on the rotating end side. As a combination means, the ring body is provided with a clamp mechanism having a structure in which a segment group made of filling reinforced resin having a vertically divided shape grips the metal tube via a ring-shaped isolation layer. And

  Moreover, the metal pipe bending apparatus (Claim 2) of the present invention is the metal pipe bending apparatus according to Claim 1, wherein the pusher is also connected to the rear end side of the metal pipe. As described above, a segment group made of filling reinforced resin in a shape in which the ring body is divided vertically is provided with a clamp mechanism having a structure in which the metal tube is gripped through a ring-shaped isolation layer. .

  Furthermore, the metal pipe bending apparatus according to the present invention (Claim 3) is the metal pipe bending apparatus according to Claims 1 and 2, wherein the clamp mechanism is a metal pipe having various outer diameters. It is characterized by comprising a plurality of series of segment groups having dimensional specifications so that isolation layers having various inner diameters conforming to the above can be formed.

  Moreover, the metal pipe bending apparatus (Claim 4) of the present invention is the metal pipe bending apparatus according to Claims 1 to 3, further comprising the number of divisions related to the vertical division of the segment group. Is characterized in that the number of divisions is set so that the weight of each segment is 20 kg or less.

  Moreover, the metal pipe bending apparatus (Claim 5) of the present invention is the metal pipe bending apparatus according to any one of Claims 1 to 4, wherein the segment group has a large inner peripheral surface. It is characterized in that it is a concavo-convex surface having a single shape or a mixture of a plurality of shapes among a dot shape, a line array shape, and a mesh shape.

  Moreover, the metal pipe bending apparatus (Claim 6) of the present invention is the metal pipe bending apparatus according to any one of Claims 1 to 5, wherein the filling reinforcing resin is made of a reactive curable resin as a substrate. And a reinforcing component is a resin filled with 10 to 30% by volume of any one or more of carbon short fibers, glass short fibers, ceramic short fibers, and glass flakes. .

  Moreover, the bending method (Claim 7) of the metal pipe of the present invention is a bending method performed by providing the metal pipe to the metal pipe bending apparatus according to Claims 1 to 6, further comprising a metal The pipe is used in the above-described metal pipe bending apparatus, and the metal pipe is gripped with a clamping force of 10 to 30% of its yield strength by the clamp mechanism to be bent.

  In such a metal pipe bending apparatus (Claims 1 and 2) and a bending method (Claim 7) of the present invention, the filling reinforced resin segment has a compressive strength equivalent to that of metal. In this case, the elastic modulus of the resin material that is the substrate of the segment is a small value of about 5 to 10% of the steel material of the typical material of the metal tube. Elastic deformation easily occurs in the segment, and the segment group of the isolation layer comes into contact with the tube body, and an equalized tightening force that is not concentrated acts on the tube body. Therefore, even if the tightening force is increased to the limit of the material strength such as the yield strength of the pipe material, no indentation is generated in the metal pipe.

  Moreover, in the metal pipe bending apparatus (Claim 3) and the bending method (Claim 7) of the present invention, the bending process of the metal pipes of various outer diameters simply replaces the segment group with one having the appropriate size. You can do it. Since the specific gravity of the filling reinforcing resin is about 20% of that of the steel material, the weight of the segment is light and easy to attach and detach.

  Furthermore, in the metal pipe bending apparatus (Claim 4) and the bending method (Claim 7) of the present invention, by setting the minimum number of segments so that the unit weight of the segment is 20 kg or less, the safety with respect to attachment and detachment is achieved. Both work efficiency is ensured.

  Further, in the metal pipe bending apparatus (Claim 5) and the bending process method (Claim 7) of the present invention, when an oil film is present on the metal pipe, a slip is generated unless the tightening load reaches the film breakage load. To happen. As described above, since the load is difficult to concentrate on the ring-shaped member, slip due to the oil film is likely to occur. However, if the inner diameter side is a concavo-convex surface, the load concentrates on the contact portion when the convex portion having only a small area starts to contact, and the slip is avoided by the action of cutting the oil film at this stage.

  Moreover, in the metal pipe bending apparatus (Claim 6) and the bending method (Claim 7) of the present invention, if the reinforcing component is a short fiber or flake, the casting production is different from the long fiber. Since it is easy, even a small number can be manufactured at low cost.

  A configuration of an embodiment (first embodiment) of a metal pipe bending apparatus of the present invention will be described with reference to the drawings. 1A is a plan view of the metal tube bending apparatus 20, FIG. 1B is a BB cross-sectional view of the clamp mechanism 30, that is, a vertical cross-sectional view in the metal tube longitudinal direction, and FIG. -C sectional view, that is, a vertical sectional view orthogonal to the longitudinal direction of the metal tube.

  The metal pipe bending apparatus 20 (see FIG. 1A) includes an inductor 21, a cooling mechanism 22, a rotating arm 23, a guide roller 26, and a pusher 27 for bending the metal pipe 10. Since these may be the same as conventional ones, the main point will be described. The inductor 21 is composed of a coil or the like that is energized from a high-frequency power source (not shown), and is configured to inductively heat a short section in the longitudinal direction of the metal tube 10 in a ring shape. It has become. The cooling mechanism 22 includes an annular tube or the like in which a large number of spray holes are formed inward. The cooling mechanism 22 is installed adjacent to the inductor 21 and is supplied with water from a water supply facility (not shown). The heating part by 21 is followed and cooled. In many cases, the inductor 21 is made of a metal tube and has a structure in which a hollow portion serves as a cooling water channel for water cooling of the inductor 21. It also serves as the mechanism 22.

  Further, the rotating arm 23 clamps the tip 11 of the metal tube 10 to restrict the path of the metal tube tip 11 in an arc shape, and the guide roller 26 supports the intermediate part of the metal tube 10 from below. In addition, by restricting the displacement on both sides, the portion of the metal tube 10 that has not been bent is caused to advance straight in the longitudinal direction of the metal tube, and the pusher 27 clamps the rear end portion 12 of the metal tube 10 to form the metal The tube 10 is propelled from the rear end side. A bending moment applying mechanism for bending and deforming the metal tube 10 locally heated by the inductor 21 sequentially from one end side includes a rotating arm 23 and a pusher 27, and is provided at the arm rotating end 24 of the rotating arm 23. The first clamp mechanism 25 is mounted as a means for coupling with the metal tube front end portion 11, and the second clamp mechanism 29 is disposed as a means for coupling with the metal tube rear end portion 12 at the pusher action portion 28 of the pusher 27. It is installed.

A clamp mechanism 30 having the same structure is employed for both the first clamp mechanism 25 and the second clamp mechanism 29. The clamp mechanism 30 (see FIGS. 1B and 1C) includes gripping members 31 to 34 made of an openable / closable annular member, an inner peripheral surface thereof, and the metal tube 10. And a ring-shaped liner (35) interposed in an isolation layer between the outer peripheral surface and the outer peripheral surface.
Each of the gripping members 31 to 34 includes a fixed gripping member 31, a movable gripping member 32, a hinge shaft 33, and a tightening bolt 34, each of which is made of a strong metal or the like. 31 is fixed to the arm rotation end 24 and the pusher action portion 28, but the movable gripping member 32 can be opened and closed by swinging around the hinge shaft 33 when the tightening bolt 34 is loosened. When the tightening bolt 34 is tightened, a tightening force is exerted on the metal tube 10 via the ring-shaped liner (35).

The ring-shaped liner (35) is composed of a plurality of segments 35, 35,..., Each of which is formed by dividing a ring body into vertically divided segments 35, for example, four segments in the illustrated example. Occupies most of the isolation layer.
The segment 35 is attached to the fixed gripping member 31 or the movable gripping member 32 with a key 36, so that it can be easily replaced. Also, unlike the prior art, it is manufactured from a filling reinforced resin by casting or molding. As the filling reinforcing resin, a reactive curable resin is used as a substrate, and as the reinforcing component, any one or a plurality of carbon short fibers, glass short fibers, ceramic short fibers, and glass flakes is used. It is a resin filled with ˜30 vol%.

The specific gravity of such a filling reinforcing resin is approximately 1.2 to 2.0. On the other hand, the specific gravity of a steel material that is a typical material of the metal tube 10 is approximately 7.85. Therefore, since the specific gravity of the filling reinforcing resin is only about 20% of the specific gravity of the metal tube 10, the segment 35 is light.
Moreover, as said reaction curable resin, a phenol resin, an epoxy resin, etc. are easy to use, and the elasticity modulus of such a resin material is about 8-20 kN / mm < ² > in general. On the other hand, the elastic modulus of a steel material that is a typical material of the metal tube 10 is approximately 200 kN / mm ² . Therefore, the elastic modulus of the substrate of the segment 35 remains as small as about 4 to 10% of the elastic modulus of the metal tube 10.
However, the compression strength of the filling reinforced resin is around 300 N / mm ^2, which is comparable to the compression strength of a general steel material.

  A metal tube bending method performed using the metal tube bending apparatus 20 of this embodiment (first embodiment) will be described with reference to the drawings. FIG. 1A is a plan view of a metal tube 10 bent by a metal tube bending apparatus 20, and FIGS. 1B and 1C are views of clamping the metal tube 10 by a clamp mechanism 30. FIG. It is a vertical sectional view, (b) is a BB sectional view along the metal tube longitudinal direction, (c) is a CC sectional view orthogonal to the metal tube longitudinal direction.

The metal pipe 10 to be bent is, for example, a carbon steel pipe for pressure piping specified in JIS G 3454, and is provided to the metal pipe bending apparatus 20 in a straight state.
The metal tube 10 is set with the metal tube bending apparatus 20 in the initial state. That is, the pivot arm 23 is pivoted so that the arm pivot end 24 is brought close to the inductor 21, the pusher 27 is also operated to retract the pusher action portion 28, and the first clamp mechanism 25 is also the first clamp mechanism 25. By opening the 2 clamp mechanism 29, the metal pipe bending apparatus 20 is set to an initial state. Then, the metal tube 10 is suspended by, for example, a crane, the metal tube front end portion 11 is placed on the guide roller 26, and the metal tube rear end portion 12 is held by the second clamp mechanism 29.

  Then, the pusher action portion 28 is advanced until the metal tube tip 11 passes through the cooling mechanism 22 and the inductor 21 and reaches the first clamp mechanism 25, and the metal tube tip 11 is gripped by the first clamp mechanism 25. Hold it. The metal tube 10 is gripped by the first and second clamp mechanisms 25 and 29 (see FIGS. 1B and 1C) with an appropriate tightening force by appropriately tightening the tightening bolt 34. The clamping force is preferably about 10 to 30% of the yield strength of the metal tube 10, and the setting is performed by, for example, connecting appropriate segment groups 35, 35,. 29, or when a segment group 35, 35,... Is attached to the first and second clamp mechanisms 25, 29, for example, an appropriate pressure measuring tool (not shown) such as a load cell is also provided. Can be performed easily and accurately.

  After setting the metal tube 10, the inductor 21 is energized with high frequency and the metal tube 10 is advanced by the pusher 27 while water is passed through the cooling mechanism 22. If it does so, a bending moment will be added to the metal pipe 10 by control of the rotation arm 23, and the longitudinal direction short section of the metal pipe 10 will be induction-heated cyclically | annularly by the inductor 21, Therefore The heating part will be bent. The bent heating part is cooled by the water discharged from the adjacent cooling mechanism 22. Then, as the metal tube 10 advances, the heating portion where the bending occurs in the metal tube 10 and the cooling portion where the bending is fixed move sequentially from the end of the metal tube 11 toward the rear end 12 of the metal tube.

  In this way, the metal tube 10 is bent with the desired radius of curvature (see FIG. 1A). At that time, since a bending moment is acting on the metal tube 10, the first and second clamp mechanisms 25 and 29 holding the metal tube end portions 11 and 12 with a strong tightening force are not biased. Although it cannot be avoided, since the elastic modulus of the substrate of the segment 35 is as small as about 5 to 10% of that of the metal tube 10, the segment 35 is easily elastically deformed, and the segment group 35 intervening in the isolation layer, 35,... Are in contact with the metal tube 10, and a non-concentrated equalized tightening force acts on the metal tube 10, so that no indentation is generated in the metal tube 10. Since the compression strength of the segment 35 is comparable to that of metal, there is no inconvenience even if the tightening force is made much higher than 30% of the yield strength of the metal tube 10 which is the upper limit of the preferred value described above.

  Another embodiment (second embodiment) of the metal pipe bending apparatus and bending method of the present invention will be described with reference to the drawings. 2A and 2B show the structure of the clamp mechanism 40 that holds the metal tube 10, wherein FIG. 2A is a sectional view taken along the line AA-AA, and FIG. 2C is a sectional view taken along the line BB-BB. FIG. 3 is a correspondence table between the pipe outer diameter and the appropriate number of segment divisions.

  This metal tube bending apparatus is different from the above-described metal tube bending apparatus 20 in that the clamp mechanism 30 is partially modified to be the clamp mechanism 40, and the clamp mechanism 40 is the clamp mechanism 30 described above. Unlike the segment groups 35, 35,..., The segment groups 41, 43,... Are interposed in an isolation layer between the inner peripheral surface of the holding members 31, 32 and the outer peripheral surface of the metal tube 10. It is a point. While the segment groups 35, 35,... Were divided into four by vertical division (see FIG. 1 (c)), the segment groups 41, 43,. 2 (see FIG. 2B)), divided into two by horizontal division (see FIG. 2A), and further divided into two by layer division (see FIG. 2B), for a total of 16 divisions.

The segment group 41, 43,... Divided into two layers includes an outer layer segment 41 near the gripping members 31, 32 and an inner layer segment 43 near the metal tube 10. Similarly to the segment 35, the outer layer segment 41 is easily attached to and detached from the gripping members 31 and 32 by the key 42, and the inner layer segment 43 is also easily attached to and detached from the outer layer segment 41 in the same manner.
When the metal pipe 10 is a carbon steel pipe for pressure piping as defined in JIS G 3454, the outer diameter is first determined by selecting the nominal diameter, and the thickness or It is determined up to the inner diameter.

  In this way, the clamping mechanism 40 can be used with a small number of members so that sufficient freedom of selection can be ensured by effectively utilizing the existence of the standard in which the outer diameter of the pipe is unified regardless of the thickness of the pipe. In this case, a plurality of series of segment groups 41, 43,..., Whose dimensions are adjusted so as to form isolation layers having various inner diameters suitable for the metal tube 10 having various outer diameters are provided. For example, the 200A segment group and the 400A segment group have different inner diameters but have the same outer diameter, so the gripping members 31 to 34 can be shared. The 500A segment group and the 600A segment group also have different inner diameters. Since the diameters are equal, the holding members 31 to 34 can be shared.

Therefore, in many cases, bending of the metal pipe 10 having various outer diameters can be performed only by replacing the segment groups 41, 43,.
Moreover, since the specific gravity of the filling reinforcing resin is small, the weight of the segment groups 41, 43,... Is light, but in the clamp mechanism 40, both the outer layer segment 41 and the inner layer segment 43 are 20 kg or less due to the division. Since the number of divisions related to the vertical division of the segment groups 41, 43,... Is set to the minimum number of segments where the unit weight of the segment is 20 kg or less, both safety and work efficiency can be ensured in connection with attachment / detachment. An appropriate integer is selected according to the outer diameter of 10 (see FIG. 3).

  The configuration of another embodiment (third embodiment) of the metal pipe bending apparatus of the present invention will be described with reference to the drawings. 4A to 4C are surface views of the uneven surface on the inner diameter side peripheral surface of the segments 35 and 43, respectively.

The uneven surface shown in FIG. 4A is a typical example of a multipoint shape, and the dot-like convex portions 52 are scattered in the net-like concave portions 51.
The uneven surface shown in FIG. 4B is a typical example of a line array, and the line array recesses 53 and the line array protrusions 54 are alternately arranged.
The irregular surface shown in FIG. 4C is a typical example of a mesh shape, and dot-like recesses 55 are scattered in the mesh-like projections 56.

These uneven surfaces are easily formed by mold transfer or the like, but other manufacturing methods may be used. For example, the inner peripheral surface of the segments 35 and 43 can be formed flat at the time of molding, and the surface can be made into the line-string-like convex portion 53 or the mesh-like convex portion 56 by subsequent mechanical grinding.
The convex portions 52, 53, and 56 have a preferable diameter and width of about 2 mm to 10 mm, and a preferable height of about 1 mm to 3 mm. From the viewpoint of oil film cutting, the cross-sectional shape of the convex portions 52, 53, and 56 is preferably a mountain shape or a trapezoid shape that is close to a square shape.

  Since the above-described metal pipe bending method of the present invention has been implemented in about six aspects using the above-described metal pipe bending apparatus of the present invention, this will be described together with two comparative examples. FIG. 5 is a table showing the conditions and results of the comparative test.

  Two types of steel pipes (JIS G 3454 / STPG schedule 40) with outer diameters of 216.3 mm and 267.4 mm are used by using the clamp mechanism 30 provided with the holding members 31 and 32 for the outer diameter pipe body of 318.5 mm. The ring body segment groups 35, 35,... Having a half thickness with an outer diameter of 318.5 mm were gripped with various tightening forces, and the occurrence of tightening indentations was visually determined.

  Test conditions and indentation determination results are shown in the table (see FIG. 5). As can be seen from the results, the present invention grips a steel pipe through an isolation layer composed of a segment-strength layer made of filled reinforcing resin. In the example, there is no tightening indentation over a high tightening pressure, whereas in the comparative example in which gripping is performed in the steel pipe-steel contact mode, an indentation is generated at a medium or higher tightening pressure. The superiority of was confirmed.

[Others]
In Embodiment 3 described above, the inner diameter side circumferential surface of the segments 35, 43 is a single point shape such as multi-point, line array, mesh, or the like (see FIG. 4). The uneven surface shape of the surface may be a mixture of these shapes.
In Example 1 described above, the case where only the carbon short fiber is included as the reinforcing component of the filling reinforcing resin forming the segment 35 and the case where only the glass flake is included are disclosed, but the glass short fiber and the ceramic short fiber are disclosed. The same result can be obtained when only one is included, or when any plural of these short fibers and glass flakes are mixed.

  The metal pipe bending apparatus and bending method of the present invention can be applied to various metal pipes such as stainless steel, aluminum-based, titanium-based, cast steel, cast iron and the like in addition to the steel pipe described above. it can.

1 shows a structure and a bending method of a metal tube bending apparatus according to an embodiment (first embodiment) of the present invention, wherein (a) is a plan view of a metal tube bent by a metal tube bending apparatus; b) is a cross-sectional view taken along the line B-B where the metal tube is clamped, and FIG. About other embodiment (2nd form) of this invention, the structure of a clamp mechanism is shown, (a) is AA-AA sectional drawing which clamps a metal pipe, (c) is the BB-BB sectional drawing. It is. It is a correspondence table | surface with a pipe outer diameter and an appropriate number of segment divisions. About other embodiment (3rd form) of this invention, (a)-(c) are all surface views of the uneven surface of the internal peripheral side surface of a segment. It is a table | surface which shows the conditions and result of a comparative test about Example 1 of this invention.

Explanation of symbols

10 ... Metal tube, 11 ... Metal tube tip, 12 ... Metal tube rear end,
20 ... Metal pipe bending device,
21 ... Inductor, 22 ... Cooling mechanism, 23 ... Rotating arm,
24 ... arm rotation end, 25 ... first clamping mechanism,
26 ... Guide roller, 27 ... Pusher,
28 ... Pusher action part, 29 ... 2nd clamp mechanism,
30 ... Clamp mechanism,
31 ... Fixed gripping member, 32 ... Movable gripping member, 33 ... Hinge shaft,
34 ... Tightening bolt, 35 ... Segment, 36 ... Key,
40 ... Clamp mechanism,
41 ... outer layer segment, 42 ... key, 43 ... inner layer segment,
51 ... concave, 52 ... dotted convex, 53 ... concave,
54 ... Linear convex portion, 55 ... concave portion, 56 ... mesh convex portion

Claims (7)

An inductor for inductively heating a short section in the longitudinal direction of the metal pipe to be bent, a cooling mechanism for following and cooling the heating portion by the inductor, and a path on the tip side of the metal pipe is regulated in an arc shape In a metal tube bending apparatus comprising a turning arm and a bending moment adding mechanism that has a pusher for propelling the metal tube from the rear end side and sequentially bends and deforms the metal tube from one end side.
The rotating arm has a separating layer in which a group of segments made of filling reinforced resin in a ring shape is connected in a ring shape as a means for joining the tip end side of the metal tube on the rotating end side. A clamp mechanism having a structure for holding the metal tube via
A metal pipe bending apparatus characterized by that.   The pusher also grips the metal tube as a means for joining with the rear end side of the metal tube through an isolation layer in which a ring-reinforced segment segment made of filling reinforcing resin is connected in a ring shape. The metal pipe bending apparatus according to claim 1, further comprising a clamping mechanism having a holding structure.   2. The clamp mechanism includes a plurality of series of segment groups whose dimensions are adjusted so as to form isolation layers having various inner diameters suitable for metal pipes having various outer diameters. Alternatively, the metal pipe bending apparatus according to claim 2.   The number of divisions related to the vertical division of the segment group is set to the number of divisions in which the weight of each segment is 20 kg or less. Metal pipe bending machine.   The segment group is characterized in that the inner peripheral side peripheral surface is a concavo-convex surface by any one of multi-point shape, line array shape, and mesh shape or a mixture of a plurality of shapes. The metal pipe bending apparatus as described in any one of Claims 1 thru | or 4.   The filling reinforcing resin has a reaction curable resin as a substrate, and 10 to 30 vol% of any one or more of carbon short fibers, glass short fibers, ceramic short fibers, and glass flakes as a reinforcing component. The metal pipe bending apparatus according to any one of claims 1 to 5, wherein the apparatus is a filled resin.   The metal tube is used in the metal tube bending apparatus according to any one of claims 1 to 6, and the metal tube is clamped with a clamping force of 10 to 30% of its yield strength by the clamp mechanism and bent. A method of bending a metal tube, characterized in that the metal tube is processed.

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