JP2015217396A - Method for frictional pressure-welding of metallic hollow member and member for power generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for frictional pressure-welding of a metallic hollow member which can suppress generation of inner burrs, and a member for power generation facility.SOLUTION: In a method for frictional pressure-welding of a metallic hollow member according to an embodiment, a pipeline 10 and a pipeline 20 are joined with each other by frictional pressure-welding. This frictional pressure-welding method includes: a process in which notches 11, 21 are formed on an inner periphery of at least one joint end side of the pipeline 10 and the pipeline 20; a process in which the pipeline 10 and the pipeline 20 are coaxially held; and a process in which joint end surfaces 12, 22 of the pipeline 10 and the pipeline 20 are confronted with each other and are pressured in an axial direction, and at the same time, the pipeline 10 and the pipeline 20 are rotated and frictionally welded to each other.

Description

  Embodiments described herein relate generally to a friction welding method for a metal hollow member and a member for power generation equipment.

  Conventionally, pipes for power generation facilities and turbine rotor structures, which are large metal structures, are joined mainly by arc welding. However, in welding joining, construction takes time and a skilled welder is required. Further, in welding that undergoes a melting process, depending on the combination of materials to be joined, joint strength may be reduced, or joining itself may not be possible.

  In addition to such welding, there is friction welding as one of the joining methods of metal materials. In friction welding, for example, a pair of cylindrical tubes are arranged on the same axis, and the joint is heated and joined by frictional heat generated by pressing the other side while rotating one side. At this time, the material extruded to the inside and outside of the cylindrical tube is discharged as burrs at the joint.

  As for the conventional friction welding method for metal hollow structures, a friction welding method for improving the reliability of the joint is disclosed by suppressing the occurrence of the edge of the burr corner that becomes the starting point of fatigue fracture. . Moreover, the joining method which joins large sized structures, such as a turbine rotor structure, by applying the non-contact heating from the outside etc. is disclosed.

JP 2004-141933 A JP 2012-115884 A

  As described above, when the metal hollow structure is joined by the conventional friction welding method, inherently unnecessary burrs are generated on the inner diameter side and the outer diameter side of the joint portion. A burr generated on the inner diameter side (hereinafter referred to as an inner burr) is more difficult to cut than a burr on the outer diameter side (hereinafter referred to as an outer burr). In many cases, the internal burr cannot be removed due to the structure.

  In addition, the inner burr may become a starting point of fracture as a stress concentration part or may be a resistance of a fluid flowing in the metal hollow structure. For this reason, the application range of friction welding has been limited.

  The problem to be solved by the present invention is to provide a friction welding method for a metal hollow member and a member for power generation equipment that can suppress the occurrence of internal burrs.

  In the friction welding method of the metal hollow member of the embodiment, the first metal hollow member and the second metal hollow member are joined by friction welding. The friction welding method includes a step of forming a notch portion in the circumferential direction on the inner periphery of at least one of the first metal hollow member and the second metal hollow member on the joining end side, and The step of holding the metal hollow member and the second metal hollow member on the same axis, the joining end faces of the first metal hollow member and the second metal hollow member are butted together and pressed in the axial direction, And rotating and friction-joining the first metal hollow member or the second metal hollow member.

It is a figure which shows the cross section containing the central axis of piping joined by the friction welding method of the metal hollow member of 1st Embodiment. It is an enlarged view of the X section of FIG. It is a figure which shows the cross section containing the central axis of the piping joined by the friction welding method of the metal hollow member of 1st Embodiment. It is a flowchart for demonstrating the process of the friction welding method of the metal hollow member of 1st Embodiment. It is a side view in the state where piping was held for explaining the process of the friction welding method of the metal hollow member of a 1st embodiment. It is a figure which shows the cross section containing the central axis of piping for demonstrating the process of the friction welding method of the metal hollow member of 1st Embodiment. It is an enlarged view equivalent to the X section of Drawing 1 which shows the notch part of other composition of piping which carries out friction welding by the friction welding method of the metal hollow member of a 1st embodiment. It is an enlarged view equivalent to the X section of Drawing 1 which shows the notch part of other composition of piping which carries out friction welding by the friction welding method of the metal hollow member of a 1st embodiment. It is an enlarged view equivalent to the X section of Drawing 1 which shows the notch part of other composition of piping which carries out friction welding by the friction welding method of the metal hollow member of a 1st embodiment. It is an enlarged view equivalent to the X section of Drawing 1 which shows the notch part of other composition of piping which carries out friction welding by the friction welding method of the metal hollow member of a 1st embodiment. It is a figure which shows the cross section containing the central axis of piping joined by the friction welding method of the metal hollow member of 2nd Embodiment. It is a perspective view which shows the joining end surface of one piping joined by the friction welding method of the metal hollow member of 2nd Embodiment. It is a flowchart for demonstrating the process of the friction welding method of the metal hollow member of 2nd Embodiment. It is a figure which shows the cross section containing the central axis of the piping joined by the friction welding method of the metal hollow member of 2nd Embodiment. It is a perspective view which shows the joining end surface of the other structure of piping joined by the friction welding method of the metal hollow member of 2nd Embodiment. It is the top view which looked at the joining end surface of other composition of one piping joined by the friction welding method of the metal hollow member of a 2nd embodiment from the front. It is the top view which looked at the joining end surface of other composition of the other piping joined by the friction welding method of the metal hollow member of a 2nd embodiment from the front. It is a figure which shows the cross section containing the central axis of piping joined by the friction welding method of the metal hollow member of 3rd Embodiment. It is a flowchart for demonstrating the process of the friction welding method of the metal hollow member of 3rd Embodiment. It is a figure which shows the cross section containing the central axis of piping in the friction welding process of the friction welding method of the metal hollow member of 3rd Embodiment. It is a figure which shows the cross section containing the center axis | shaft of piping of the other structure in the friction welding process of the friction welding method of the metal hollow member of 3rd Embodiment. It is a figure which shows the cross section containing the central axis of piping joined by the friction welding method of the metal hollow member of 4th Embodiment. In the friction welding method of the metal hollow member of 4th Embodiment, it is a figure which shows the cross section containing the central axis of the piping which showed the mode of the internal burr | flash in the case of providing a heating means and a cooling means. It is a flowchart for demonstrating the process of the friction welding method of the metal hollow member of 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a view showing a cross section including a central axis of pipes 10 and 20 joined by the friction welding method of the metal hollow member according to the first embodiment. FIG. 2 is an enlarged view of a portion X in FIG. 1 and 2 show a state where the pipes 10 and 20 are held coaxially. FIG. 3 is a view showing a cross section including the central axis of the pipes 10 and 20 joined by the friction welding method of the metal hollow member according to the first embodiment. In the embodiments described below, the same components are denoted by the same reference numerals, and redundant descriptions are omitted or simplified.

  Here, the pipes 10 and 20 will be described as examples of the metal hollow member. The pipe 10 functions as a first metal hollow member, and the pipe 20 functions as a second metal hollow member.

  First, the configuration of the pipes 10 and 20 that are friction-welded will be described.

  The pipes 10 and 20 are made of, for example, a cylindrical metal material. Although the outer diameter of the piping 10 and 20 is not specifically limited, For example, the thing of about 30 mm-500 mm can be illustrated. In the center of the pipes 10 and 20, for example, hollow portions 10a and 20a penetrating in the axial direction are formed. As the metal material, for example, carbon steel, heat resistant steel, stainless steel, Ni-based alloy, or the like is used. Moreover, the piping 10 and the piping 20 may be comprised with the same material, and may be comprised with a different material.

  As shown in FIGS. 1 and 2, notches 11 and 21 are formed in the inner periphery of the pipes 10 and 20 on the joint end side in the circumferential direction. The notch surfaces 11a and 21a of the notches 11 and 21 are linearly inclined toward the central axis side from the joining end surfaces 12 and 22 in the axial direction of the pipes 10 and 20. That is, the notches 11 and 21 are annular spaces whose cross-sectional areas decrease from the joining end faces 12 and 22 in the axial direction of the pipes 10 and 20. In other words, the notches 11 and 21 are frustoconical spaces from which the hollow portions 10a and 20a are removed. In addition, the joining end surfaces 12 and 22 are comprised by the plane perpendicular | vertical with respect to an axial direction, for example.

As shown in FIG. 1, for example, when the notches 11 and 21 are formed in both the pipes 10 and 20, one notch in the pipe 10 in the axial cross section including the central axis of the pipes 10 and 20. It is preferable that the area A, which is the sum of the area A1 of 11 and the area A2 of one notch 21 in the pipe 20, satisfies the relationship of the following equation (1).
1/6 × L × T ≦ A ≦ 1/2 × L × T (1)

  Here, as shown in FIGS. 1 and 3, the lengths of the pipes 10 and 20 change before and after the friction welding. L in the formula (1) is the total axial length of the pipe 10 and the pipe 20 before the friction welding (L1 + L2), and the axial length of the joined body composed of the pipe 10 and the pipe 20 after the friction welding. The length obtained by subtracting the length L3 (L1 + L2-L3). That is, L is the axial length reduced by friction welding in the pipe 10 and the pipe 20. T is the thickness of the pipe 10 and the pipe 20. The wall thickness of the pipe 10 and the wall thickness of the pipe 20 are equal.

  FIG. 1 illustrates a configuration in which the area A1 is equal to the area A2. For example, when the pipe 10 and the pipe 20 are made of the same material, the amount of internal burr coming out of each is almost the same. Therefore, a configuration in which the area A1 and the area A2 are equal is suitable, for example, when the pipe 10 and the pipe 20 are made of the same material.

  When the pipe 10 and the pipe 20 are friction-welded, it is necessary to form notches 11 and 21 having a sufficiently large size in order to suppress internal burrs that protrude to the inner peripheral side of the joint of the pipes 10 and 20. is there. However, if the notches 11 and 21 are too large (the spaces of the notches 11 and 21 are too wide), the inner burrs that fill the notches 11 and 21 are relatively small, and the joint 30 is also after friction welding. A large space due to the notches 11 and 21 remains in the vicinity of. As a result, problems such as formation of stress concentration portions and insufficient thickness in the vicinity of the joint portion 30 occur. On the other hand, if the notches 11 and 21 are too small (the spaces of the notches 11 and 21 are too narrow), the amount of internal burr that can be accommodated in the notches 11 and 21 is limited. Therefore, it is not possible to suppress internal burrs that protrude to the inner peripheral side of the joint portion 30.

  Therefore, the size of the notches 11 and 21 needs to be an appropriate size considering the amount of burrs. Therefore, by setting the area A to be “1/6 × L × T” or more, the inner burr can be reliably accommodated in the notches 11 and 21. Further, by setting the area A to be “½ × L × T” or less, it is possible to prevent a large space in the vicinity of the joint portion 30 due to the notches 11 and 21 from being formed, and to form a stress concentration portion or the joint portion 30. Insufficient wall thickness in the vicinity of is prevented.

  In addition, it is preferable that the specific shape of the notches 11 and 21 is set based on, for example, a result of a preliminary test or numerical calculation using a small model similar in shape to a pipe that is friction-welded in advance.

Moreover, it is preferable that the thickness H of the joining end surfaces 12 and 22 satisfy | fill the relationship of following Formula (2).
1/5 × T ≦ H ≦ 4/5 × T (2)

  Note that T is the thickness of the pipe 10 and the pipe 20 as described above. By setting H to “1/5 × T” or more, it is possible to ensure appropriate joining end faces 12 and 22. By setting H to “4/5 × T” or less, the notches 11 and 21 that accommodate the inner burr can be formed in an appropriate range in the vicinity of the joint 30.

  Next, the process of the friction welding method of a metal hollow member is demonstrated.

  FIG. 4 is a flowchart for explaining a process of the friction welding method of the metal hollow member according to the first embodiment. FIG. 5 is a side view of the state in which the pipes 10 and 20 are held for explaining the steps of the friction welding method for the metal hollow member according to the first embodiment. FIG. 6 is a view showing a cross section including the central axis of the pipes 10 and 20 for explaining the process of the friction welding method for the metal hollow member according to the first embodiment.

  First, the notches 11 and 21 are formed in the inner periphery on the joint end side of the pipes 10 and 20 in the circumferential direction (notch portion forming step: step S1). The notches 11 and 21 are formed by cutting the inner periphery on the joint end side of the pipes 10 and 20 using, for example, a lathe or the like while being rotatably supported by a bearing or the like. . In addition, the structure of the notch parts 11 and 21 formed is as having mentioned above.

  Subsequently, the pipe 10 and the pipe 20 are held coaxially (pipe holding step: step S2). The other end of the pipe 10 on the side different from the joining end face 12 side is chucked by a fixing member (not shown), for example, and the pipe 10 is fixed so as not to rotate. On the other hand, the other end of the pipe 20 on the side different from the joining end face 22 side is chucked by a rotatable fixing member (not shown), and the pipe 20 is fixed rotatably.

  Here, as shown in FIG. 5, the pipe 10 is preferably supported by a bearing 40. The pipe 20 is also preferably supported by the bearing 41. The bearings 40 and 41 are configured by, for example, a rolling bearing or a sliding bearing. Thus, by providing the rotating pipe 20 with the bearing 41, it is possible to suppress bending due to its own weight and rotational vibration during rotation. On the other hand, the stationary side pipe 10 can suppress bending due to its own weight by providing the bearing 40. In addition, by providing the bearings 40 and 41, the pipe 10 and the pipe 20 can be reliably held on the same axis, and friction welding can be performed.

  Subsequently, the joint end face 12 of the pipe 10 and the joint end face 22 of the pipe 20 are butted together. Then, as shown in FIG. 6, the pipe 20 is rotated while applying axial pressure, and the pipe 10 and the pipe 20 are joined by friction welding (friction welding process: step S3). At the time of friction welding, the inner burr is accommodated in the notches 11 and 21 as shown in FIG. Therefore, the protrusion of the inner burr from the inside of the joint portion 30 is suppressed. Although an example in which the friction welding is performed by rotating the pipe 20 is shown here, the pipe 20 may be fixed and the pipe 10 may be rotated.

  After the friction welding, the joined body shown in FIG. 3 is obtained. Although not shown in FIG. 3, an external burr may occur after friction welding. This outer burr can be easily removed from the surroundings by, for example, a grinder.

  In the friction welding process, the friction welding may be performed, for example, in an inert gas atmosphere. Thereby, the oxidation of the joint portion 30 during joining can be prevented. As the inert gas, for example, argon (Ar) can be used.

  Here, examples of the pipes 10 and 20 include pipes used for steam turbine equipment. Specific examples of the pipes 10 and 20 include pipes constituting a main steam pipe, a reheat steam pipe, an extraction pipe, a crossover pipe, and the like. Moreover, as a metal hollow member, the turbine rotor structure etc. which comprise a turbine rotor other than piping are mentioned, for example. These metal hollow members function as members for power generation equipment.

  As described above, according to the friction welding method of the metal hollow member according to the first embodiment, the notches 11 and 21 are provided on the inner periphery of the joints 10 and 20 on the joining end side, so that the joint 30 is provided. It is possible to suppress the internal burr from protruding from the inside. Thereby, the reliability of the joint part 30 can be improved.

  Here, the structure of the notch parts 11 and 21 is not restricted to the structure mentioned above. 7 to 10 show the notches 11 and 21 of other configurations of the pipes 10 and 20 that are friction welded by the friction welding method of the metal hollow member of the first embodiment. It is a corresponding enlarged view.

  As shown in FIG. 7, in this cross section, the notched surfaces 11 a and 21 a of the notched portions 11 and 21 are inclined toward the central axis side from the joining end surfaces 12 and 22 in the axial direction of the pipes 10 and 20. You may be comprised with two straight lines. That is, the notches 11 and 21 are configured by two annular spaces having different inclination angles with a cross-sectional area decreasing from the joining end surfaces 12 and 22 in the axial direction of the pipes 10 and 20. In the cross section shown in FIG. 7, the area of the notch 11 is equal to the area of the notch 21.

  Here, in the cross section shown in FIG. 7, an example in which the cut-out surfaces 11 a and 21 a are configured by two straight lines is shown, but the cross section may be configured by three or more straight lines. Further, the notched surfaces 11a and 21a may be formed of a curved surface that is convex outward, a curved surface that is convex inward, or the like.

  Moreover, as shown in FIG. 8, you may comprise the notch parts 11 and 21 in the cyclic | annular space from which the center of the cylinder removed. That is, the notches 11 and 21 may be formed of a cylindrical space from which the hollow portions 10a and 20a are removed.

  Also in the notches 11 and 21 shown in FIG. 7 and FIG. 8 described above, the relationship shown by the above-described equations (1) and (2) is established.

  Furthermore, as shown in FIG. 9, the shape of the notch 11 and the shape of the notch 21 may be different. In this case, in the cross section shown in FIG. 9, the area A1 of the notch 11 is different from the area A2 of the notch 21. Here, an example is shown in which the notches 11 and 21 are frustoconical spaces from which the hollow portions 10a and 20a are removed, but the present invention can also be applied to the configurations shown in FIGS.

  The configuration in which the shape of the notch portion 11 and the shape of the notch portion 21 are different in this way is suitable when, for example, the pipe 10 and the pipe 20 are made of different materials. For example, when the area A1 of the notch 11 is larger than the area A2 of the notch 21, the pipe 10 is preferably made of a material having a softening temperature lower than that of the pipe 20, for example. Thus, the configuration shown in FIG. 9 is suitable for a material combination in which the pipe 10 and the pipe 20 have different softening behaviors, for example.

  The notches 11 and 21 shown in FIG. 9 also satisfy the relationship of the above-described formula (1). In this case, the area A1 and the area A2 are different. The thickness H1 of the joining end face 12 of the pipe 10 and the thickness H2 of the joining end face 22 of the pipe 20 shown in FIG. 9 each satisfy the relationship of the above-described formula (2). The wall thickness T of the pipe 10 is equal to the wall thickness T of the pipe 20.

  Moreover, as shown in FIG. 10, you may form a notch part over the circumferential direction in the inner periphery by the side of the joining end part of the piping 10 or the piping 20. As shown in FIG. In addition, in FIG. 10, the example which provided the notch part 11 in the piping 10 is shown. The notch 11 is an annular space whose cross-sectional area decreases as it goes from the joint end surface 12 in the axial direction of the pipe 10, similarly to the notch 11 shown in FIG. 2. On the other hand, the joining end face 22 of the pipe 20 is configured by a plane perpendicular to the axial direction over the thickness T of the pipe 20. In addition, the shape shown in FIG. 7 or 8 may be sufficient as the shape of the notch part 11. FIG.

  Thus, even in the case of the configuration in which the notch 11 is provided only in the pipe 10, the relationship of the above-described formula (1) is satisfied. In this case, the area A2 of the pipe 20 is “0”. Further, the thickness H1 of the joint end surface 12 of the pipe 10 in the pipe 10 having the notch 11 satisfies the relationship of the above-described formula (2). Here, an example in which the notch 11 is provided only in the pipe 10 is shown, but the notch may be provided only in the pipe 20.

  Even when the pipes 10 and 20 shown in FIGS. 7 to 10 are friction-welded, the pipe 10 and the pipe 20 are friction-welded through the same process as that of the metal hollow member friction-welding method described above. The And by providing the notch parts 11 and 21 in the inner periphery of the joining end part side of the piping 10 and 20, or providing a notch part in the inner periphery of the joining end part side of the pipe 10 or the piping 20, the joining part. The protrusion of the inner burr from the inside of 30 can be suppressed. Thereby, the reliability of the joint part 30 can be improved.

(Second Embodiment)
FIG. 11 is a diagram illustrating a cross section including the central axis of the pipes 10 and 20 to be joined by the friction welding method of the metal hollow member according to the second embodiment. FIG. 12 is a perspective view showing a joining end face 12 of one pipe 10 to be joined by the friction welding method of the metal hollow member according to the second embodiment.

  In the second embodiment, the pipes 10 and 20 will be described as examples of the metal hollow member. The pipe 10 functions as a first metal hollow member, and the pipe 20 functions as a second metal hollow member.

  As shown in FIGS. 11 and 12, the joining end faces 12 and 22 of the pipes 10 and 20 are configured by a plane perpendicular to the axial direction over the wall thickness T of the pipes 10 and 20. The joint end surfaces 12 and 22 are provided with groove portions 50 and 60.

  For example, as shown in FIG. 12, the groove portions 50 and 60 are composed of a plurality of grooves 51 and 61 that are formed radially around the center of the end surface including the joint end surfaces 12 and 22. That is, the groove portions 50 and 60 are constituted by a plurality of grooves 51 and 61 formed at equal intervals in the circumferential direction on the joining end surfaces 12 and 22. In addition, the structure of the groove part 60 of the joining end surface 22 in the piping 20 is the same as the structure shown in FIG.

As shown in FIG. 11, when both the pipes 10 and 20 are provided with the groove parts 50 and 60, the volume V1 of the groove part 50 in the joint end surface 12 of the pipe 10 and the volume V2 of the groove part 60 in the joint end surface 22 of the pipe 20 are set. It is preferable that the total volume V satisfies the relationship of the following formula (3). The volume V1 of the groove 50 is the sum of the volumes of the grooves 51, and the volume V2 of the groove 60 is the sum of the volumes of the grooves 61.
1/6 × L × S ≦ V ≦ 1/2 × L × S (3)

  Here, S is the area of each of the joining end faces 12 and 22 including the grooves 50 and 60 of the pipe 10 and the pipe 20. That is, in the groove portions 50 and 60 shown in FIGS. 11 and 12, the total area of the area of the joining end surface 12 and the area of the bottom surface of the groove portion 50 is S, and the area of the joining end surface 22 and the area of the bottom surface of the groove portion 60 are The total area is S. L is as described above.

  FIG. 11 illustrates a configuration in which the volume V1 and the volume V2 are equal. For example, when the pipe 10 and the pipe 20 are made of the same material, the amount of burrs coming out of each is almost the same. Therefore, the configuration in which the volume V1 and the volume V2 are equal is suitable when, for example, the pipe 10 and the pipe 20 are made of the same material.

  In order to accommodate burrs such as inner burrs and outer burrs generated at the joints 30 of the pipes 10 and 20 when the pipes 10 and 20 are friction welded, the amount of burrs generated is taken into account. The optimum volume of the grooves 50 and 60 is required. Therefore, by setting the volume V to “1/6 × L × S” or more, the burrs can be reliably accommodated in the grooves 50 and 60. Moreover, the space | gap which arises in the groove parts 50 and 60 can be suppressed by making the volume V below "1/2 * L * S", and the fall of the intensity | strength of the junction part 30 can be prevented. Note that the width, depth, number, shape, and the like of the grooves 51 and 61 in the groove portions 50 and 60 are set based on, for example, results of preliminary tests or numerical calculations using a small model similar in shape to a pipe that is friction-welded in advance. It is preferred that

  Next, the process of the friction welding method of a metal hollow member is demonstrated.

  FIG. 13 is a flowchart for explaining the steps of the friction welding method for a hollow metal member according to the second embodiment. FIG. 14 is a view showing a cross section including the central axis of the pipes 10 and 20 joined by the friction welding method of the metal hollow member according to the second embodiment.

  First, the groove parts 50 and 60 are formed in the joining end surfaces 12 and 22 of the pipes 10 and 20 (groove part forming step: step S10). That is, grooves 51 and 61 are formed in the joining end surfaces 12 and 22. The grooves 50 and 60 are formed, for example, by cutting the inner periphery on the joint end side of the pipes 10 and 20 using a milling machine or the like while being rotatably supported by a bearing or the like.

  (Piping holding process: Step S11) and (Friction welding process: Step S12) are respectively the same as (Piping holding process: Step S2) and (Friction welding process: Step S3) in the first embodiment. .

  Here, in the friction welding process, the burr is accommodated in the grooves 51 and 61 as shown in FIG. Therefore, the protrusion of the burr | flash to the inner side and the outer side of the junction part 30 is suppressed.

  As described above, according to the friction welding method of the metal hollow member of the second embodiment, the groove portions 50 and 60 are provided on the joint end surfaces 12 and 22 of the pipes 10 and 20, so that the inside and outside of the joint portion 30. It is possible to suppress burrs from protruding. Thereby, the reliability of the joint part 30 can be improved.

  Here, the structure of the groove parts 50 and 60 is not restricted to the structure mentioned above.

  FIG. 15 is a perspective view showing joining end faces 12 and 22 of other configurations of the pipes 10 and 20 joined by the friction welding method of the metal hollow member according to the second embodiment. In addition, since the structure of the groove part 60 of the joining end surface 22 is the same as the structure of the groove part 50 of the joining end surface 12, both code | symbol is attached | subjected to FIG.

  As shown in FIG. 15, the groove portions 50 and 60 formed on the joining end surfaces 12 and 22 of the pipes 10 and 20 are ring-shaped grooves 52 and 62. The grooves 52 and 62 are formed in the circumferential direction between the outer edge and the inner edge of the joint end faces 12 and 22. Note that the outer edge and the inner edge are not included between the outer edge and the inner edge. Therefore, the shape of the groove parts 50 and 60 in the cross section including the central axis of the pipes 10 and 20 is a U-shape. By providing such groove portions 50 and 60, the burr is accommodated in the grooves 52 and 62. Therefore, the protrusion amount of the burr | flash to the inner side and the outer side of the junction part 30 is reduced. The groove portions 50 and 60 shown in FIG. 15 also satisfy the relationship of the above-described formula (3).

  FIG. 16: is the top view which looked at the joining end surface 12 of the other structure of the one piping 10 joined by the friction welding method of the metal hollow member of 2nd Embodiment from the front. FIG. 17 is a plan view of a joining end face 22 of another configuration of the other pipe 20 joined by the friction welding method of the metal hollow member according to the second embodiment as viewed from the front.

  As shown in FIGS. 16 and 17, the configuration of the groove 50 and the configuration of the groove 60 may be different. In this case, the volume V1 of the groove 50 and the volume V2 of the groove 60 are different. Here, the shape (the width, depth, and radial length of the groove) of the groove 51 of the groove part 50 and the groove 61 of the groove part 60 are the same. The configuration of the different groove portions 50 and 60 can also be applied to the configuration shown in FIG.

  Such a configuration in which the volume V1 of the groove 50 and the volume V2 of the groove 60 are different is suitable, for example, when the pipe 10 and the pipe 20 are made of different materials. For example, when the volume V1 of the groove part 50 is larger than the volume V2 of the groove part 60, it is preferable that the piping 10 is comprised with the material whose softening temperature is lower than the piping 20, for example. The groove portions 50 and 60 shown in FIGS. 16 and 17 also satisfy the relationship of the above-described formula (3).

  Moreover, you may provide a groove part in the joining end surface of the piping 10 or the piping 20. FIG. That is, the joint end face of one pipe is provided with a groove portion, and the joint end face of the other pipe is constituted by a plane perpendicular to the axial direction over the thickness T of the pipe. The shape of the groove part may be constituted by a plurality of radially formed grooves as shown in FIG. 12, or may be a ring-like groove as shown in FIG. Thus, even when a groove is provided in only one of the pipes, the relationship of the above-described formula (3) is satisfied. In this case, the volume of the groove portion of the other pipe is “0”.

  Even in the case of friction welding the pipes 10 and 20 having the joining end surfaces of the other configurations described above, the pipe 10 and the pipe are subjected to the same process as the process of the friction welding method of the metal hollow member described with reference to FIG. 20 is friction-welded. And by providing the groove parts 50 and 60 in the joining end surfaces 12 and 22 of the pipes 10 and 20, or by providing the groove part in the joining end faces of the pipe 10 or the pipe 20, the protrusion of the burr to the inner side or the outer side of the joint part 30 is prevented. Can be suppressed. Thereby, the reliability of the joint part 30 can be improved.

(Third embodiment)
FIG. 18 is a view showing a cross section including the central axis of the pipes 10 and 20 joined by the friction welding method of the metal hollow member of the third embodiment. In the third embodiment, the pipes 10 and 20 will be described as examples of the metal hollow member. The pipe 10 functions as a first metal hollow member, and the pipe 20 functions as a second metal hollow member.

  As shown in FIG. 18, the joining end faces 12 and 22 of the pipes 10 and 20 are configured by planes perpendicular to the axial direction.

  Around the ends of the pipes 10 and 20 on the joint end faces 12 and 22 side, heating means 70 and 80 are provided with a predetermined distance from the outer surface of the pipes 10 and 20. The heating means 70 and 80 heat the end portion from the outer peripheral side in a non-contact manner. Any heating means 70 and 80 may be used as long as the end portions are heated from the outer peripheral side in a non-contact manner, and examples thereof include a high-frequency induction heating coil and laser light. For example, a plurality of heating means 70 and 80 are provided in the circumferential direction. Further, when the pipes 10 and 20 are butted together, the heating means 70 and 80 are provided so as to be movable in the butting direction corresponding to the operation.

  In the hollow portions 10a and 20a of the pipes 10 and 20, a cooling means 90 for cooling the joint portion 30 from the inner peripheral side is provided. The cooling unit 90 includes, for example, a jet part 91 that jets a cooling medium. The ejection portion 91 has, for example, a plurality of holes 91 a on the peripheral surface facing the joint portion 30. And the ejection part 91 ejects the refrigerant | coolant supplied by the supply pipe | tube 92 to the junction part 30. FIG.

  In addition, the structure of the ejection part 91 is not restricted to an above-described structure. For example, the jet part 91 having one or more holes 91a facing the joint part 30 may be rotated about the central axis of the supply pipe 92 as a rotation axis, and the refrigerant may be jetted to the joint part 30. Examples of the refrigerant include compressed air and argon (Ar) gas, but are not particularly limited.

  The temperature distribution in the radial direction of the joint 30 can be controlled by the heating means 70 and 80 and the cooling means 90 described above. For example, by providing the heating means 70 and 80 and the cooling means 90, the temperature on the outer peripheral side of the joining end faces 12 and 22 can be intentionally adjusted higher than the temperature on the inner peripheral side. By adjusting in this way, softening on the outer peripheral side is promoted, and softening on the inner peripheral side is suppressed. As a result, burrs generated during friction welding increase the amount of discharge as external burrs. As a result, the amount of internal burr discharged can be reduced.

  The amount of heating by the heating means 70 and 80 and the flow rate of the refrigerant ejected by the cooling means 90 are set based on the results of preliminary tests and numerical calculations, for example, using a small model similar in shape to the piping that is friction-welded in advance. It is preferred that

  Next, the process of the friction welding method of a metal hollow member is demonstrated.

  FIG. 19 is a flowchart for explaining the steps of the friction welding method for a metal hollow member according to the third embodiment. FIG. 20 is a view showing a cross section including the central axis of the pipes 10 and 20 in the friction welding process of the friction welding method of the metal hollow member according to the third embodiment.

  First, the pipe 10 and the pipe 20 are held coaxially (pipe holding step: step S20). Note that (Pipe holding step: Step S20) is the same as (Pipe holding step: Step S2) in the first embodiment.

  Subsequently, the end portions on the joint end faces 12 and 22 side of the pipe 10 and the pipe 20 are non-contact heated from the outer peripheral side (non-contact heating step: step S21).

  Here, when the piping 10 and the piping 20 are comprised with the same material, they are heated on the same conditions by the heating means 70 and 80, for example. When the pipe 10 and the pipe 20 are made of different materials, the heating means 70 and the heating means 80 may be operated under different conditions. For example, when the softening temperature of the pipe 10 is higher than the softening temperature of the pipe 20, the output of the heating unit 70 may be higher than the output of the heating unit 80. As a result, burrs can be generated uniformly and the amount of burrs discharged can be reduced.

  It should be noted that the material and shape of the pipes 10 and 20 (areas of the joining end faces 12 and 22, the dimensions of the pipes 10 and 20, etc.), the rotating speed of the pipe to be rotated, and the pressing between the pipe 10 and the pipe 20 during friction welding It is preferable to calculate, for example, the relationship between the output of the heating means 70 and 80 and the temperature of the heating portion of the pipes 10 and 20 by numerical calculation based on pressure or the like. And based on the calculated database, the output of the heating means 70 and 80, a heating time, etc. are set, and the heating part of the piping 10 and 20 is heated to predetermined temperature. Here, the predetermined temperature is a temperature at which a sufficient amount of heat can be supplied only by frictional heat in order to perform appropriate friction welding.

  Subsequently, after the heating unit of the pipes 10 and 20 reaches a predetermined temperature, the joint end surface 12 of the pipe 10 and the joint end surface 22 of the pipe 20 are abutted. Then, as shown in FIG. 20, the pipe 20 is rotated while applying axial pressure, and the pipe 10 and the pipe 20 are joined by friction welding (friction welding process: step S22).

  Although an example in which the friction welding is performed by rotating the pipe 20 is shown here, the pipe 20 may be fixed and the pipe 10 may be rotated. Further, when the pipe 10 and the pipe 20 are butted together, the heating means 70 and 80 also move in the butting direction corresponding to the operation. In the friction welding process, the heating by the heating means 70 and 80 is continued.

  In the friction welding process, friction welding is performed, and the joint 30 between the pipe 10 and the pipe 20 is cooled from the inner peripheral side (cooling process: step S23). In this cooling step, the coolant is blown onto the joint portion 30 from the inner peripheral side. In this way, the ends of the pipes 10 and 20 on the joint end faces 12 and 22 side are heated from the outer peripheral side and the joint 30 is cooled from the inner peripheral side, thereby reducing the amount of internal burr discharged. can do.

  A joined body is obtained after the friction welding process and the cooling process. In addition, an external burr | flash may generate | occur | produce in a joined body. This outer burr can be easily removed from the surroundings by, for example, a grinder.

  As described above, according to the friction welding method of the metal hollow member of the third embodiment, the end portions on the joining end surfaces 12 and 22 side of the pipes 10 and 20 are heated from the outer peripheral side, and the joint portions are joined from the inner peripheral side. By cooling 30, the protrusion of burrs to the inside of the joint portion 30 can be suppressed. Thereby, the reliability of the joint part 30 can be improved.

  Here, the cooling means 90 used in the cooling step is not limited to the above-described configuration. FIG. 21 is a diagram illustrating a cross section including the central axis of the pipes 10 and 20 having another configuration in the friction welding process of the friction welding method of the metal hollow member according to the third embodiment.

  As shown in FIG. 21, the cooling means 90 may be constituted by, for example, a cylindrical cooling pipe 100 having a slightly smaller diameter than the inner diameters of the hollow portions 10 a and 20 a of the pipes 10 and 20. The cooling pipe 100 has, for example, a double pipe structure including an outer pipe 101 and an inner pipe 102 accommodated in the outer pipe 101. As shown in FIG. 21, the one end 102 a of the inner tube 102 is disposed away from the one end 101 a of the outer tube 101. As a result, as indicated by arrows in FIG. 21, the refrigerant that has flowed through the inner tube 102 can be guided to the annular passage between the inner tube 102 and the outer tube 101. The refrigerant guided to the annular passage cools the inner burr in contact with the outer pipe 101 and is discharged to the outside of the cooling pipe 100.

  The cooling pipe 100 is inserted into the hollow portions 10 a and 20 a of the pipes 10 and 20. In the friction welding process, friction welding is performed, and a coolant is flowed into the cooling pipe 100 to cool the joint portion 30 between the pipe 10 and the pipe 20 from the inner peripheral side (cooling process: step S23). Note that the tip of the cooling pipe 100 is inserted until it passes through at least the joint 30. As the refrigerant, for example, a liquid such as water, a gas such as compressed air or argon gas can be used.

  When this cooling means 90 is used, the generated internal burr comes into contact with the cooling pipe 100 and is cooled. Thereby, the temperature on the outer peripheral side of the joining end faces 12 and 22 can be intentionally adjusted higher than the temperature on the inner peripheral side. By adjusting in this way, softening on the outer peripheral side is promoted, and softening on the inner peripheral side is suppressed. As a result, burrs generated during friction welding increase the amount of discharge as external burrs. As a result, the amount of internal burr discharged can be reduced. Furthermore, the protrusion of the inner burr can be suppressed by the cooling pipe 100.

  In the friction welding method for a metal hollow member according to the third embodiment, for example, when the pipes 10 and 20 are made of a material that is sufficiently softened by the amount of heat generated in the friction welding, the non-contact by the heating means is performed. The heating step may not be provided. In this case, only the joint 30 is cooled during the friction welding process. Even in this case, the amount of internal burr discharged can be reduced.

(Fourth embodiment)
FIG. 22 is a view showing a cross section including the central axis of the pipes 10 and 20 to be joined by the friction welding method of the metal hollow member according to the fourth embodiment. In the fourth embodiment, the pipes 10 and 20 will be described as examples of the metal hollow member. The pipe 10 functions as a first metal hollow member, and the pipe 20 functions as a second metal hollow member.

  As shown in FIG. 22, the joining end surfaces 12 and 22 of the pipes 10 and 20 are configured by a plane perpendicular to the axial direction.

  Around the ends of the pipes 10 and 20 on the joint end faces 12 and 22 side, heating means 70 and 80 for heating the ends from the outer peripheral side in a non-contact manner with a predetermined distance from the outer surface of the pipes 10 and 20. Is provided. As shown in FIG. 22, the heating means 70 and 80 are 1/2 to 3 times as long as the wall thickness T of the pipe 10 and the pipe 20 in the axial direction from the joint end faces 12 and 22 of the pipe 10 and the pipe 20. It is preferable to heat the range of N. In addition, the wall thickness T of the pipe 10 and the pipe 20 is equal.

  Here, by setting the length N in the axial direction where the heating means 70 and 80 are provided to be 1/2 or more of the wall thickness T of the pipes 10 and 20, the protrusion of the inner burr can be suppressed. Even if the axial length N in which the heating means 70 and 80 are provided is larger than three times the wall thickness T of the pipes 10 and 20, the effect of suppressing the protrusion of the inner burr hardly changes. Therefore, the axial length N in which the heating means 70 and 80 are provided is set to be three times or less the wall thickness T of the pipes 10 and 20.

  In addition, the heating means 70 and 80 which heat the above-mentioned range are provided with two or more over the circumferential direction, for example. The examples of the heating means 70 and 80 are as described above.

  Further, cooling means 110 and 120 for cooling the pipes 10 and 20 from the outer peripheral side are provided on the outer side in the axial direction where the heating means 70 and 80 are provided. The cooling units 110 and 120 eject the refrigerant toward the outer peripheral surfaces of the pipes 10 and 20. Thereby, the outer side in the axial direction where the heating means 70 and 80 are provided is cooled. A plurality of cooling means 110 and 120 are provided in the circumferential direction corresponding to the heating means 70 and 80, for example.

  Examples of the refrigerant include compressed air and argon (Ar) gas, but are not particularly limited. The cooling means 110 and 120 are composed of, for example, an injection nozzle. The cooling means 110 and 120 are provided to be movable in the abutting direction corresponding to the operation when the pipe 10 and the pipe 20 are abutted.

  By the heating means 70 and 80 and the cooling means 110 and 120 described above, the temperature distribution in the axial direction of the ends of the pipes 10 and 20 on the side of the joining end faces 12 and 22 can be controlled. For example, by providing the heating means 70 and 80 and the cooling means 110 and 120, only a portion having a predetermined length in the axial direction from the joint end faces 12 and 22 can be heated in advance. As a result, the region deformed during friction welding is increased in the axial direction as compared with the case where no heating is performed.

  Here, FIG. 23 shows the state of internal burrs when the heating means 70 and 80 and the cooling means 110 and 120 are provided in the friction welding method of the metal hollow member of the fourth embodiment. It is a figure which shows the cross section of 20 including a central axis. In FIG. 23, the above-described predetermined range is heated by the heating means 70 and 80, and the outer side in the axial direction where the heating means 70 and 80 are provided is cooled from the outer peripheral side by the cooling means 110 and 120.

  As shown in FIG. 23, by providing the heating means 70 and 80 and the cooling means 110 and 120, an optimal axial temperature distribution can be obtained at the ends of the pipes 10 and 20 on the joining end faces 12 and 22 side. As a result, the inner burrs do not protrude locally on the inner periphery of the joint portion 30, and a slight inner burrs that are almost uniformly flat are generated over the axial length N where the heating means 70, 80 are provided. Therefore, the internal burr | flash which protrudes to the inner periphery of the junction part 30 can be suppressed.

  Note that the amount of heating by the heating means 70 and 80 and the flow rate of the refrigerant ejected by the cooling means 110 and 120 are based on, for example, the results of preliminary tests or numerical calculations using a small model similar in shape to the pipe that is friction-welded in advance. Are preferably set.

  Next, the process of the friction welding method of a metal hollow member is demonstrated.

  FIG. 24 is a flowchart for explaining the steps of the friction welding method for a metal hollow member according to the fourth embodiment.

  First, the pipe 10 and the pipe 20 are held coaxially (pipe holding step: step S30). Note that (Pipe holding step: Step S30) is the same as (Pipe holding step: Step S2) in the first embodiment.

  Subsequently, the pipes 10 and 20 in a predetermined range in the axial direction are heated from the outer peripheral side in a non-contact manner from the respective joining end faces 12 and 22 of the pipe 10 and the pipe 20 (non-contact heating step: step S31).

  Here, when the piping 10 and the piping 20 are comprised with the same material, they are heated on the same conditions by the heating means 70 and 80, for example. When the pipe 10 and the pipe 20 are made of different materials, the heating means 70 and the heating means 80 may be operated under different conditions. For example, when the softening temperature of the pipe 10 is higher than the softening temperature of the pipe 20, the output of the heating unit 70 may be higher than the output of the heating unit 80. Accordingly, burrs can be uniformly generated in the axial direction, and inner burrs protruding on the inner periphery of the joint portion 30 can be suppressed.

  It should be noted that the material and shape of the pipes 10 and 20 (areas of the joining end faces 12 and 22, the dimensions of the pipes 10 and 20, etc.), the rotating speed of the pipe to be rotated, and the pressing between the pipe 10 and the pipe 20 during friction welding It is preferable to calculate, for example, the relationship between the output of the heating means 70 and 80 and the temperature of the heating portion of the pipes 10 and 20 by numerical calculation based on pressure or the like. And based on the calculated database, the output of the heating means 70 and 80, a heating time, etc. are set, and the heating part of the piping 10 and 20 is heated to predetermined temperature. Here, the predetermined temperature is a temperature at which a sufficient amount of heat can be supplied only by frictional heat in order to perform appropriate friction welding.

  Moreover, when performing non-contact heating, the said range of the piping 10 and 20 is non-contact heated, and the axial direction outer side of this non-contact heating range is cooled from an outer peripheral side (cooling process: step S32). In this cooling step, the refrigerant is blown to the outside in the axial direction of the range where the pipes 10 and 20 are heated in a non-contact manner.

  Subsequently, after the heating unit of the pipes 10 and 20 reaches a predetermined temperature, the joint end surface 12 of the pipe 10 and the joint end surface 22 of the pipe 20 are abutted. Then, as shown in FIG. 23, the pipe 20 is rotated while applying axial pressure, and the pipe 10 and the pipe 20 are joined by friction welding (friction welding process: step S33).

  Although an example in which the friction welding is performed by rotating the pipe 20 is shown here, the pipe 20 may be fixed and the pipe 10 may be rotated. Further, when the pipe 10 and the pipe 20 are abutted, the heating means 70 and 80 and the cooling means 110 and 120 also move in the abutting direction corresponding to the operation. In the friction welding process, the heating by the heating means 70 and 80 and the cooling by the cooling means 110 and 120 are continued.

  In the non-contact heating process and the cooling process, the inner burr does not protrude locally on the inner periphery of the joint portion 30, and the inner surface is substantially uniformly flat over the axial length N where the heating means 70 and 80 are provided. Slight burr occurs.

  After the friction welding process, for example, a joined body as shown in FIG. 23 is obtained. In addition, an external burr | flash may generate | occur | produce in a joined body. This outer burr can be easily removed from the surroundings by, for example, a grinder.

  As described above, according to the friction welding method of the metal hollow member of the fourth embodiment, the pipes 10 and 20 in a predetermined range are heated from the outer peripheral side in the axial direction from the joining end faces 12 and 22. By cooling the outside in the axial direction of the range to be performed from the outer peripheral side, it is possible to suppress the occurrence of internal burrs that locally protrude on the inner periphery of the joint portion 30. Thereby, the reliability of the joint part 30 can be improved.

  In the friction welding method of the metal hollow member according to the fourth embodiment, for example, depending on the material and dimensions of the pipes 10 and 20 and the construction conditions of the friction welding, the pipes 10 and 20 in the predetermined range described above are arranged on the outer peripheral side. In some cases, an optimal temperature distribution in the axial direction may be obtained at the ends of the pipes 10 and 20 on the side of the joining end faces 12 and 22 only by heating. In this case, the cooling means 110 and 120, that is, the cooling process may not be provided. Even in this case, it is possible to suppress the occurrence of internal burrs that locally protrude on the inner periphery of the joint portion 30.

  According to the embodiment described above, it is possible to suppress the occurrence of internal burrs.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10,20 ... Piping, 10a, 20a ... Hollow part, 11, 21 ... Notch part, 11a, 21a ... Notch surface, 12, 22 ... Joining end surface, 30 ... Joining part, 40, 41 ... Bearing, 50, 60 ... groove part, 51, 52, 61 ... groove, 70, 80 ... heating means, 90, 110, 120 ... cooling means, 91 ... jetting part, 92 ... supply pipe, 100 ... cooling pipe, 101 ... outer pipe, 101a, 102a ... one end, 102 ... inner tube.

Claims (15)

In the friction welding method of the metal hollow member for joining the first metal hollow member and the second metal hollow member by friction welding,
Forming a notch portion in the circumferential direction on the inner periphery of at least one joining end of the first metal hollow member and the second metal hollow member;
Holding the first metal hollow member and the second metal hollow member coaxially;
The first metal hollow member and the second metal hollow member are butted against each other, and the first metal hollow member or the second metal hollow member is rotated and frictionally bonded while pressing in the axial direction. And a friction welding method for a metal hollow member. When the notch is formed in both the first metal hollow member and the second metal hollow member,
In the axial cross section including the central axes of the first metal hollow member and the second metal hollow member, the area of one notch in the first metal hollow member and the second metal hollow member 2. The friction welding method for a metal hollow member according to claim 1, wherein an area A obtained by summing up the areas of one notch satisfies the relationship of the following expression.
1/6 × L × T ≦ A ≦ 1/2 × L × T
Here, L is the sum of the axial lengths of the first metal hollow member and the second metal hollow member before the friction welding, and the first metal hollow member and the second metal after the friction welding. The length of the joined body composed of the metal hollow member is reduced by the axial length, and T is the thickness of the first metal hollow member and the second metal hollow member.   The method of friction welding of a metal hollow member according to claim 2, wherein an area of the notch portion of the first metal hollow member is equal to an area of the notch portion of the second metal hollow member.   The method of friction welding of a metal hollow member according to claim 2, wherein an area of the notch portion of the first metal hollow member is different from an area of the notch portion of the second metal hollow member. When the notch is formed in the first metal hollow member or the second metal hollow member,
The area A of one notch satisfies the relationship of the following expression in an axial cross section including a central axis of the first metal hollow member and the second metal hollow member. The friction welding method of the metal hollow member of description.
1/6 × L × T ≦ A ≦ 1/2 × L × T
Here, L is the sum of the axial lengths of the first metal hollow member and the second metal hollow member before the friction welding, and the first metal hollow member and the second metal after the friction welding. The length of the joined body composed of the metal hollow member is reduced by the axial length, and T is the thickness of the first metal hollow member and the second metal hollow member. In the friction welding method of the metal hollow member for joining the first metal hollow member and the second metal hollow member by friction welding,
Forming a groove in at least one joining end face of the first metal hollow member and the second metal hollow member;
Holding the first metal hollow member and the second metal hollow member coaxially;
The first metal hollow member and the second metal hollow member are butted against each other, and the first metal hollow member or the second metal hollow member is rotated and frictionally bonded while pressing in the axial direction. And a friction welding method for a metal hollow member. When the groove is formed in both the first metal hollow member and the second metal hollow member,
The hollow metal according to claim 6, wherein a volume V obtained by summing a volume of the groove portion of the first metal hollow member and a volume of the groove portion of the second metal hollow member satisfies the relationship of the following expression. Friction welding method for members.
1/6 × L × S ≦ V ≦ 1/2 × L × S
Here, L is the sum of the axial lengths of the first metal hollow member and the second metal hollow member before the friction welding, and the first metal hollow member and the second metal after the friction welding. Is a length obtained by reducing the length in the axial direction of the joined body composed of the metal hollow member, and S is a joint end surface including the groove portion of the first metal hollow member and the second metal hollow member. Each area.   The friction welding method for a metal hollow member according to claim 7, wherein the volume of the groove portion of the first metal hollow member is equal to the volume of the groove portion of the second metal hollow member.   The friction welding method for a metal hollow member according to claim 7, wherein the volume of the groove of the first metal hollow member is different from the volume of the groove of the second metal hollow member. When the groove is formed in the first metal hollow member or the second metal hollow member,
The friction welding method for a metal hollow member according to claim 6, wherein the volume V of the groove satisfies the relationship of the following equation.
1/6 × L × S ≦ V ≦ 1/2 × L × S
Here, L is the sum of the axial lengths of the first metal hollow member and the second metal hollow member before the friction welding, and the first metal hollow member and the second metal after the friction welding. The length of the joined body composed of the metal hollow member is reduced by the length in the axial direction, and S is the length of the first metal hollow member or the second metal hollow member in which the groove is formed, It is the area of the joint end face including the groove.   The friction welding method for a metal hollow member according to any one of claims 6 to 10, wherein the groove is a plurality of grooves formed radially around the center of the end face including the joining end face.   11. The metal hollow member according to claim 6, wherein the groove is a ring-shaped groove formed in a circumferential direction between an outer edge and an inner edge of the joining end surface. Friction welding method. In the friction welding method of the metal hollow member for joining the first metal hollow member and the second metal hollow member by friction welding,
Holding the first metal hollow member and the second metal hollow member coaxially;
A step of non-contact heating the end portions on the joining end face side of the first metal hollow member and the second metal hollow member from the outer peripheral side;
The first metal hollow member and the second metal hollow member are butted against each other, and the first metal hollow member or the second metal hollow member is rotated and frictionally bonded while pressing in the axial direction. And a process of
And a step of cooling the joint portion between the first metal hollow member and the second metal hollow member joint portion from the inner peripheral side during the friction joining. In the friction welding method of the metal hollow member for joining the first metal hollow member and the second metal hollow member by friction welding,
Holding the first metal hollow member and the second metal hollow member coaxially;
A length that is 1/2 to 3 times the wall thickness T of the first metal hollow member and the second metal hollow member in the axial direction from the respective joining end faces of the first metal hollow member and the second metal hollow member. Non-contact heating of the range of from the outer periphery side,
In the non-contact heating, the step of cooling the outside in the axial direction of the non-contact heating range from the outer periphery side;
The first metal hollow member and the second metal hollow member are butted against each other, and the first metal hollow member or the second metal hollow member is rotated and frictionally bonded while pressing in the axial direction. And a friction welding method for a metal hollow member.   A member for power generation equipment, which is joined by the friction welding method for metal hollow members according to any one of claims 1 to 14.

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