JP2920130B1 - Processing method of hollow cylindrical tube - Google Patents

Abstract

An object of the present invention is to provide a processing method for manufacturing a hollow cylindrical tube having excellent durability and a sufficient spring effect, and having a neck portion having a thicker end than a hem. SOLUTION: This is a processing method of forming a constriction by pressing an outer peripheral surface while rotating a metal hollow cylindrical tube. 2
By forming a W-shaped constriction 13 with the pressing member 7 having two convex portions 7a, and then pressing the central portion 13a of the constriction with the pressing member 17 that fills only the skirt portion of the desired constriction shape. , Transform the constriction into a U-shaped 23,
A constriction 33 having a V-shaped cross section is formed by pressing the central portion 23a of the constriction with a pressing member 27 having a desired constriction shape and a total shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of processing a hollow cylindrical tube for forming an annular constriction on an outer peripheral surface, such as an anode container for a sodium-sulfur battery, and more particularly, to a method for processing a hollow cylindrical tube. It relates to the processing how the hollow cylindrical tube tip to form a constriction thick Te.

[0002]

2. Description of the Related Art As shown in FIG.
The hollow cylindrical tube 31 having an annular constriction 33 on a surface 32 orthogonal to -X 'is suitably used for, for example, an anode container for a sodium-sulfur battery. Conventionally, as shown in FIG. 3, for example, as shown in FIG. 3, a hollow cylindrical tube 31 having such a constriction 33 is provided on a hollow cylindrical tube 4 with a core bar 26 (26a, 26b) having a constriction 33 to be formed and a concave portion 25 having a general shape. ) Is inserted, and the outer peripheral surface of the hollow cylindrical tube 4 is pressed by the processing roller 27 while rotating the hollow cylindrical tube 4.

[0003]

Constriction is formed by, however the method [0008] is 4 (a), the constricted tip of the thickness t ₂ is constricted skirt portion of the thickness t _3, the thickness of the hollow cylindrical tube Since the hollow cylindrical tube 31 is thinner than t ₁ , the hollow cylindrical tube 31 is connected to an anode container for a sodium-sulfur battery (hereinafter, “anode container”).
That. ) Had the following problems.

[0004] That is, as shown in FIG.
The constriction in the above gives a spring effect in the cylindrical axis direction to the anode container 42 and makes the anode container 42 expandable and contractible, so that sodium polysulfide or sulfur is solidified and the solid electrolyte tube 44 and the anode container 42 The purpose is to reduce the load generated at the joints 50 to 53 between the components due to the difference in heat shrinkage and to prevent the anode container 42 from being damaged.

Accordingly, if the thickness t ₂ of the constricted portion, particularly the tip of the constricted portion 33 is smaller than the thickness t ₃ of the constricted hem portion as in the above-described method, the strength of the constricted portion cannot be increased. However, there has been a problem that a sufficient spring effect cannot be provided and durability due to repeated expansion and contraction is poor.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a spring effect which is excellent in durability and can withstand use as an anode container for a sodium-sulfur battery. having, as shown in FIG. 4 (b), a processing method for a hollow cylindrical tube for thickness t ₂ of the tip than the thickness t ₃ of the skirt portion to produce a hollow cylindrical tube having a constricted thick To provide.

[0007]

Means for Solving the Problems According to the present invention, a hollow cylindrical tube made of metal and a cylindrical metal core having a concave portion provided in a ring shape on a surface orthogonal to the cylindrical axis are prepared. And
In a state where the hollow cylindrical tube is loosely inserted into the core, the hollow cylindrical tube and the core are fixed from the end face side by a supporting member, and the hollow cylindrical tube and the core are rotated around the cylindrical axis by rotating the supporting member. While rotating, a pressing member having a convex portion is pressed against a portion of the outer peripheral surface of the hollow cylindrical tube corresponding to the concave portion of the metal core, thereby forming an annular constriction on a surface orthogonal to the cylindrical axis of the outer peripheral surface of the hollow cylindrical tube. In a method for processing into a hollow cylindrical tube, first, a first pressing member having two convex portions has a W-shaped cross section at a portion corresponding to a concave portion of a core metal on the outer peripheral surface of the hollow cylindrical tube. Forming a constriction, and then pressing the central portion of the W-shaped constriction with a second pressing member having one convex portion that satisfies only the skirt portion of the desired constriction shape, The shape of the constriction is transformed into a U-shape, and the desired constriction and overall shape By pressing the central part of the U-shaped constriction with a third pressing member having one convex part, the cross-sectional shape is V-shaped, and compared to the skirt. A method for processing a hollow cylindrical tube, characterized in that a tip portion forms a thick constriction.

Further, according to the present invention, a hollow cylindrical tube made of metal and a cylindrical core having a concave portion formed in a ring on a surface orthogonal to the cylindrical axis are prepared. With the cylindrical tube loosely inserted, the hollow cylindrical tube and the cored bar are fixed from the end face side by a support member, and by rotating the support member, while rotating the hollow cylindrical tube and the cored bar around the cylindrical axis,
A hollow cylindrical tube is formed by pressing a pressing member having a convex portion against a portion corresponding to a concave portion of the core metal on the outer peripheral surface of the hollow cylindrical tube to form an annular constriction on a surface orthogonal to the cylindrical axis of the outer peripheral surface of the hollow cylindrical tube. First, a W-shaped constriction is formed in a portion of the outer peripheral surface of the hollow cylindrical tube corresponding to the concave portion of the metal core with a first pressing member having two convex portions. Then, by pressing a central portion of the W-shaped constriction with a third pressing member having one convex portion, which is a desired constriction shape and an overall shape, the V-shaped cross section is formed. And a method of processing a hollow cylindrical tube, characterized in that a tip portion forms a thicker neck than a hem portion.

In the present invention, the first pressing member is
It is preferable that two processing rollers are arranged in parallel, and it is preferable that the pressing member be a processing roller that rotates following the rotation of the hollow cylindrical tube. Further, in the present invention, it is preferable that the core metal is a split mold divided into two in the length direction in the vicinity of the center of the concave portion of the core metal, and one of the pieces constituting the split mold is It is preferable that the section has an axial projection, and the other section has a recess in the section that can fit into the projection, and one of the split molds is joined to one of the two support members and the other Preferably, the fragments are joined to the other of the support members.

Further, in the present invention, the sectional shape is W
When pressing the center of the constriction with a pressing member,
It is preferable to perform local annealing on the entire constriction or a portion other than the central portion .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for processing a hollow cylindrical tube having a constricted outer peripheral surface of a hollow cylindrical tube. 5 will be described.

Generally, as a method of forming a constriction in a hollow cylindrical tube, the hollow cylindrical tube 4 is loosely inserted into a cylindrical core metal 26 having a concave portion 25 formed therein, and the hollow cylindrical tube 4 and the core metal 26 are placed on both end sides. The pressing member 27 having the convex portion 27a is pressed against the portion corresponding to the concave portion 25 of the core metal 26 on the outer peripheral surface of the hollow cylindrical tube 4 while being fixed and rotated by the supporting members 28a and 28b, thereby forming the constriction 33. Is used. The hollow cylindrical tube 4 used for processing is not particularly limited as long as it is made of metal. However, when used as an anode container, aluminum or aluminum alloy having high corrosion resistance and excellent workability is used.

The metal core 26 is usually a solid cylindrical member made of metal and has an outer diameter that allows the hollow cylindrical tube 4 to be loosely inserted. The concave portion 25 is annularly provided on a plane orthogonal to the cylindrical axis XX ′ so that In order to facilitate pulling out the core metal 26 from the hollow cylindrical tube 34 after the provision of the constriction 33, the core metal 26 has a length in the vicinity of the center of the concave portion 25 in the longitudinal direction.
The split dies 26a and 26b are preferably divided into two.

When the split dies 26a and 26b are used, one of the pieces 26b constituting the split mold has an axial projection 26d on its cross section, and the other piece 26a fits on the projection 26d. It is preferable to have a recess 26c that can fit in the cross section. Pieces 26a and 26 constituting the cored bar 26
b is formed by fittingly connecting
This is because the dimensional accuracy in the axial direction of No. 3 can be increased.

The support member 28 is a member for supporting and fixing the hollow cylindrical tube 4 and the metal core 26, and is loosely inserted into the metal core 26 and the metal core 26 by two support members 28 a and 28 b. It is used such that the hollow cylindrical tube 4 is sandwiched from both end surfaces. Each of the two support members 28a and 28b is provided with a rotation mechanism. By rotating the support member 28, the sandwiched hollow cylindrical tube 4 and the core metal 26 are rotated by the cylindrical shaft X.
It is configured to rotate around −X ′. In this case, the use of the one in which one piece 26a of the cored bar is joined to one 28a of the support member and the other piece 26b is joined to the other 28b of the support member causes variation in shape. It is preferable in reducing the number.

The pressing member 27 is a member having a convex portion 27 a corresponding to the width and height of the constriction 33 to be formed on the hollow cylindrical tube 4, and is a cylindrical shaft X of the rotating hollow cylindrical tube 4.
−X ′ and a projection 27 on a portion corresponding to the recess 25 of the cored bar 26 on the outer peripheral surface of the hollow cylindrical tube 4.
By pressing a, a constriction 33 is formed on the outer peripheral surface of the hollow cylindrical tube 4. As the pressing member, for example, a processing roller having a mechanism for rotating itself can be used, but the roller shaft 27b is set in a freely rotatable state, and is rotated so as to follow the rotation of the hollow cylindrical tube 4. It is preferable to use a configured processing roller. Such a processing roller can prevent the occurrence of abrasion on the surface of the constricted tip, and can enhance the durability of the constricted portion. Therefore, when processing a member used in a corrosive atmosphere such as an anode container, particularly, It can be suitably used.

When the hollow cylindrical tube 4 is processed, for example, as shown in FIG. 5, the support members 28 are respectively inserted into the hollow cylindrical tube 4 through both the openings of the hollow cylindrical tube 4.
fragments 26a, 26b of the cored bar 26 joined to the a, 28b
Insert The length l ₂ of the cored bar 28 is set to be substantially equal to the length l ₁ of the hollow cylindrical tube 4, and when the supporting member 28 is brought into contact with the end face of the hollow cylindrical tube 4, the two cores divided are separated. It is configured such that the opposing end surfaces of the golds 26a and 26b are in contact with each other.

At this time, when the hollow cylindrical tube 4 is loosely inserted into the one of the support members 28 a through a buffer member 29 such as an annular member made of rubber, for example, the support is ensured, and the support member 28 a Of the constriction position l ₃ can be prevented. The insertion of the core metal 26 into the hollow cylindrical tube 4 can be performed, for example, by advancing the core metal pieces 26a and 26b by an air cylinder or the like.

Next, the support members 2 at both ends of the hollow cylindrical tube 4
8, both end faces abut against the hollow cylindrical tube 4 and are clamped;
The support member 28 is rotated. By rotating the support member 28, the hollow cylindrical tube 4 sandwiched between the two support members 28a and 28b rotates following the support member 28. As shown in FIG. 3B, a pressing member 27 is provided on a portion of the outer peripheral surface of the hollow cylindrical tube 4 corresponding to the concave portion 25 of the metal core 26.
The constriction 33 is formed by applying a pressure at.

In the process of forming the constriction 33, the constriction 33 gradually widens and deepens, and the hollow cylindrical tube 34
Is completed when the inner peripheral surface of the core contacts the wall of the concave portion 25 of the metal core 26. After forming the constriction 33, contrary to FIG.
The cores 26a and 26b may be pulled out of the hollow cylindrical tube 34 by an air cylinder.

According to the processing method of the present invention, in the above-described processing method, after pressing a first pressing member having two convex portions to form a constriction having a W-shaped cross section, the first pressing member has one convex portion. The cross-sectional shape is W
It is characterized in that the central part of the letter-shaped constriction is pressed to form a letter V-shaped constriction. According to the method of the present invention, there is less uneven thickness compared to the case where the constriction is formed in one step, and it is possible to prevent the thickness of the constriction tip from becoming thinner, as shown in FIG. It Does, can be thickness t ₂ of the tip than the thickness t ₃ of the skirt forms a constricted thick. In addition, since the amount of deformation at the constricted tip, that is, the degree of processing, is small, it is possible to form a constricted part with little work hardening of the material and rich in elasticity. Hereinafter, the processing method of the present invention will be described with reference to the example of FIG.

In the present invention, the first pressing member is
A pressing member having two convex portions, which is a member for forming a constriction having a W-shaped cross section by pressing a portion corresponding to a concave portion of a metal core on the outer peripheral surface of a hollow cylindrical tube.
Therefore, the shape and the like of the hollow cylindrical tube are not limited as long as a W-shaped constriction can be formed on the outer peripheral surface thereof. For example, as shown in FIG. Can be suitably used. Even in this case, for the same reason as described above, it is possible to use a processing roller configured to make the roller shaft 7b freely rotatable and to rotate following the rotation of the hollow cylindrical tube 4. preferable.

The core metal used in the present invention does not need to be in contact with the entire inner peripheral surface of the hollow cylindrical tube as long as it can be loosely inserted into the hollow cylindrical tube to be processed. A core 10 having a smaller diameter than the tube 4 is also included. Such a cored bar is preferable in that even when the cored bar has a W-shaped cross section, it is easy to pull out the cored bar after processing, but as shown in FIG. 23 (or V-shaped constriction) can also be used.

When a core metal having a W-shaped cross section is used, for example, a split mold 60 as shown in FIG.
To 63 may be used. The split mold includes a separate core member 60, an outer core 61, and a split mold 62 at the center of the neck.
This is a split mold composed of 63, and after the hollow cylindrical tube 14 is processed in the state shown in FIG. 10, the core 60 is pulled out, so that the split molds 62 and 63 of the constricted portion can be disassembled and taken out. is there.

In the present invention, the second pressing member is
A member formed by the first pressing member 7 and having a central portion of the constriction 13 having a W-shaped cross section, that is, one convex portion 17a for pressing the protruding portion 13a; Means that only hem is satisfied. According to the second pressing member 17, the central portion of the W-shaped constriction 13, that is, the protruding portion 13a can be inverted so that the cross-sectional shape of the constriction can be changed to the U-shaped 23. As the second pressing member 17, for example, as shown in FIG. 1B, the skirt portion has the same R as that of the third pressing member, but the tip portion is cut off to be flat. be able to.

In the present invention, the third pressing member is
One convex portion 27a which is the desired constriction shape 33 and the overall shape
And a member for pressing the central portion 23a of the U-shaped constriction 23. Third pressing member 2
7 forms a constriction 33 having a desired constriction shape, that is, a V-shaped cross section and a desired width and depth.

When the constriction is formed in this manner, the amount of deformation at the constriction tip, that is, the degree of processing, is small.
It is possible to form a constricted portion with little work hardening of the material and rich in elasticity. Also, as shown in FIG.
Because in comparison with the thickness t ₃ of the skirt portion constricted thicker thickness t ₂ of the tip is formed, thereby improving the strength and durability of the constriction.

In the processing method of the present invention, it is sufficient to omit the processing step using the second pressing member 17 and perform only the processing step using the first pressing member 7 and the third pressing member 27. The effect can be obtained. However,
From the viewpoint of minimizing the amount of deformation at the constricted tip, that is, the degree of processing, it is preferable to perform the processing step using the second pressing member 17.

The central portion 13 a of the constriction 13 having a W-shaped cross section is connected to the second pressing member 17 or the third pressing member 2.
When pressing at 7, the W-shaped constriction 13 or a portion other than the central portion 13a (that is, an edge portion) 13b is preferably locally annealed, as shown in FIG.
More preferably, only 3b is locally annealed. By local annealing, distortion generated when pressing the central portion 13a can be removed and the portion can be softened, so that the occurrence and position of uneven thickness and cracks in the constricted portion that may occur in the process of pressing the constriction This is because deviation can be prevented. In the case where aluminum or an aluminum alloy is used for the local annealing, it is preferable to gradually cool after heating and holding at a temperature of 400 to 550 ° C.

In the case where the constriction is formed by the method of the present invention, the arrangement state of the hollow cylindrical tube is not particularly limited, and the constriction is performed in a state where the hollow cylindrical tube 4 is horizontally arranged as shown in FIG. May be formed, or a constriction may be formed in a state where the hollow cylindrical tube 4 is arranged vertically.

The hollow cylindrical tube processed by the method of the present invention has a sufficient constriction at the tip portion compared to the hem portion, so that it has a sufficient spring effect, is hardly damaged, and has a durable life. Also excellent in nature. Therefore, the hollow cylindrical tube processed by the method of the present invention can be suitably used as an anode container, and as shown in FIG. It can be. FIG. 7 shows an example of a sodium-sulfur battery using the hollow cylindrical tube 31 according to the processing method of the present invention as an anode container.

[0032]

EXAMPLES The present invention will be described in more detail with reference to examples shown in FIG. 1, but the present invention is not limited to these examples.

(Example 1) Length 520 mm, outer diameter φ9
A constriction having a width of 12 mm and a depth of 12 mm was formed in a hollow cylindrical tube having a diameter of 5 mm, an inner diameter of 90 mm, and a thickness of 2.5 mm by the following method.

As shown in FIG. 5, the hollow cylindrical tube 4
Of the core metal 6 joined to the support member by an air cylinder from both the openings of the hollow cylindrical tube 4
a, 6b were inserted. The outer diameter of the cored bar is φ89.8 mm, and the entire length of the cored bar is 5 mm when the pieces 6a and 6b are joined.
32 mm. When the core metal pieces 6a and 6b are joined, a concave portion 5 having a width of 12 mm and a depth of 12 mm is formed at the joint.

Next, the hollow cylindrical tube 4 is fixed from both end surfaces by supporting members at both ends of the hollow cylindrical tube 4, and the supporting member is rotated together with the core 6 and the hollow cylindrical tube 4 in the same manner as in FIG. A pressure is applied to a portion of the outer peripheral surface of the hollow cylindrical tube 4 corresponding to the concave portion 5 of the metal core 6 by two parallel processing rollers 7 serving as a first pressing member, thereby forming a constriction having a W-shaped cross section. 13 was formed.

Next, the second having one convex portion 17 a
The central portion 1 of the W-shaped constriction 13 by the pressing member 17
By pressing 3 a, the constriction was deformed into a U-shaped 23. As the second pressing member, FIG.
As shown in FIG. 7, a processing roller 17 of a type in which the skirt portion has the same R as that of the third pressing member 27 but the front end portion is missing in a planar shape is used.

Next, similarly, the central portion 23 a of the U-shaped constriction 23 is formed by the third pressing member 27 having the desired constriction shape 33 and one convex portion 27 a which is the entire shape.
Is pressed to form a constriction 33 having a V-shaped cross section.
Was formed. After forming the constriction 33, the rotation by the support member is stopped, and the core metals 26a, 26b are
Was pulled out of the hollow cylindrical tube. Constriction 3 formed
The thickness of the tip part of No. 3 was 2.2 mm.

(Embodiment 2) The same hollow cylindrical tube 4 as in Embodiment 1 was used, except that the processing step using the second pressing member 17a was omitted. A constriction was formed. The thickness of the tip of the formed constriction 33 was 2.2 mm.

(Comparative Example 1) The same method as in Example 1 was used except that the same hollow cylindrical tube 4 as in Example 1 was used, and the processing steps using the first pressing member 7 and the second pressing member 17 were omitted.
A constriction having a width of 12 mm and a depth of 12 mm was formed. The thickness of the tip of the formed constriction 33 was 1.5 mm.

[0040]

EFFECTS OF THE INVENTION According to the processing method of the present invention, there is less uneven thickness compared to the case where the constriction is formed in one step, and it is possible to prevent the thickness of the constricted tip portion from becoming thin, and it is possible to obtain a sufficient It has a spring effect and is excellent in durability, and can form a thick neck at the tip end compared to the skirt. In addition, since the amount of deformation at the constricted tip, that is, the degree of processing, is small, it is possible to form a constricted part with little work hardening of the material and rich in elasticity. Therefore, the hollow cylindrical tube having the constriction formed by the processing method of the present invention can be suitably used as an anode container for a sodium-sulfur battery.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view (a), (b), (c), (d) showing an example of a method for processing a hollow cylindrical tube of the present invention.

FIG. 2 is a perspective view showing an example of a hollow cylindrical tube having a constriction.

3A and 3B are schematic cross-sectional views illustrating an example of a conventional method for processing a hollow cylindrical tube.

FIG. 4A is a schematic cross-sectional view of a constricted portion formed by a conventional method, and FIG. 4B is a schematic cross-sectional view of a constricted portion formed by a method of the present invention.

FIG. 5 is a schematic sectional view (a) showing a method of inserting a metal core,
(B).

FIG. 6 is a schematic cross-sectional view showing a local annealing portion.

FIG. 7 is a schematic sectional view showing a structure of a sodium-sulfur battery.

FIGS. 8A and 8B are schematic sectional views showing one embodiment of a small-diameter cored bar.

FIGS. 9A and 9B are schematic sectional views showing another embodiment of a small-diameter cored bar.

FIGS. 10A and 10B are partial cross-sectional views (a), side cross-sectional views (b), and BB 'partial cross-sectional views (c) showing examples of a split type.
It is.

[Explanation of symbols]

4 hollow cylindrical tube 5 concave portion 6 core metal 7 pressing member
8 ... Supporting member, 9 ... Chuck for fixing hollow cylindrical tube, 10 ...
Small-diameter core metal, 13: W-shaped constriction, 14: hollow cylindrical tube having a W-shaped constriction, 15: recess, 16: core, 1
7 ... Pressing member, 20 ... Small core metal, 23 ... U-shaped neck, 24 ... Hollow cylindrical tube having U-shaped neck, 25 ...
Recessed part, 26 ... core metal, 27 ... pressing member, 28 ... supporting member,
31: a hollow cylindrical tube having a V-shaped constriction; 32, a surface orthogonal to the cylindrical axis; 33, a V-shaped constriction; 41, a sodium-sulfur battery; 42, an anode container; 43, a bottom plate;
Solid electrolyte tube, 45 ... insulator ring, 46 ... cathode metal fittings,
47: cylindrical fitting, 48: molten metal sodium, 49 ...
Conductive material for anode, 50: welded portion between cylindrical fitting and anode container, 51: joined portion between insulator ring and solid electrolyte tube, 5
2 ... Junction between insulator ring and cylindrical fitting, 53 ... Welded part between hollow cylindrical tube and anode vessel lid, 60 ... Center, 61 ... Outer core, 62, 63 ... Split die.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-105974 (JP, A) JP-A-54-137469 (JP, A) JP-A-52-15471 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) B21D 17/04 H01M 2/02 H01M 10 / 38,10 / 39

Claims (8)

(57) [Claims] 1. A hollow cylindrical tube made of metal and a cylindrical metal core having a concave portion provided in a ring shape on a surface orthogonal to the cylindrical axis are prepared, and the hollow cylindrical tube is loosely inserted into the metal core. In this state, the hollow cylindrical tube and the cored bar are fixed from the end face side by a support member, and by rotating the support member, the hollow cylindrical tube and the cored bar are rotated about the cylindrical axis, and a pressing member having a convex portion is provided. Is pressed against a portion of the outer peripheral surface of the hollow cylindrical tube corresponding to the concave portion of the core metal to form an annular constriction on a surface orthogonal to the cylindrical axis of the outer peripheral surface of the hollow cylindrical tube, First, a first pressing member having two convex portions forms a W-shaped constriction in a portion corresponding to the concave portion of the core metal on the outer peripheral surface of the hollow cylindrical tube, and then a desired constriction The second pressing member having one convex portion that satisfies only the skirt portion of the shape has the cross-sectional shape. Presses the central part of the W-shaped constriction to deform the constriction into a U-shape, and further has a third pressing member having a desired constriction shape and an overall shape. By pressing the central part of the U-shaped constriction at the cross section, the cross-sectional shape is V-shaped, and the tip forms a thicker constriction than the skirt. Processing method of hollow cylindrical tube. 2. A hollow cylindrical tube made of metal and a cylindrical metal core having a concave portion provided in a ring shape on a surface orthogonal to the cylindrical axis are prepared, and the hollow cylindrical tube is loosely inserted into the metal core. In this state, the hollow cylindrical tube and the cored bar are fixed from the end face side by a support member, and by rotating the support member, the hollow cylindrical tube and the cored bar are rotated about the cylindrical axis, and a pressing member having a convex portion is provided. Is pressed against a portion of the outer peripheral surface of the hollow cylindrical tube corresponding to the concave portion of the core metal to form an annular constriction on a surface orthogonal to the cylindrical axis of the outer peripheral surface of the hollow cylindrical tube, First, a first pressing member having two convex portions forms a W-shaped constriction in a portion corresponding to the concave portion of the core metal on the outer peripheral surface of the hollow cylindrical tube, and then a desired constriction The third pressing member having one convex portion, which has a shape and a total shape, has a W-shaped cross section. By pressing the central portion of the constriction is a cross-sectional shape is V-shaped, and a processing method for a hollow cylindrical tube, characterized in that the tip portion than the skirt forms a constricted thick. 3. The method for processing a hollow cylindrical tube according to claim 1, wherein the first pressing member is two processing rollers arranged in parallel. 4. The method of processing a hollow cylindrical tube according to claim 1, wherein the pressing member is a processing roller that rotates following the rotation of the hollow cylindrical tube. 5. The hollow cylindrical tube according to claim 1, wherein the core metal is a split mold that is divided into two in the length direction in the vicinity of the center of the concave portion of the core metal. Processing method. 6. The hollow according to claim 5, wherein one of the pieces constituting the split mold has an axial projection on a cross section thereof, and the other piece has a recess on the cross section thereof capable of fitting with the projection. Processing method of cylindrical tube. 7. The method according to claim 5, wherein one of the split mold pieces is joined to one of the two support members, and the other piece is joined to the other of the support members. 8. The W-shaped constriction is entirely annealed or a portion other than the central portion is locally annealed when the central portion of the W-shaped constriction is pressed by the pressing member. A method for processing a hollow cylindrical tube according to claim 1.