JP2006083913A - Flexible tube and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible tube suppressing leak from a boundary part of a bellows pipe and a fitting, and a method for manufacturing the same. <P>SOLUTION: The flexible tube including the bellows pipe part 1 and the fitting 2 is formed out of one metal tubular material including a part 1a to be the bellows pipe part and a part 2a to be the fitting part continuously. Consequently, the flexible tube is obtained in which a joining structure does not exist at the boundary part 3 of the bellows pipe part 1 and the fitting part 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flexible tube having a configuration in which a base is provided at a tube end portion of a metal bellows tube, and a method for manufacturing the flexible tube.

A metal bellows tube is obtained by processing a wall of a single metal tube into a bellows shape, and is flexible while being a metal tube due to its bellows structure (for example, non- Patent Document 1). Hereinafter, the metal bellows pipe is also simply referred to as “bellows pipe”.
Flexible tubes using bellows pipes are used for piping in various industrial fields, and in particular, because of high mechanical strength and airtightness due to being metal pipes, for example, high-pressure fluids in hydrogen fuel cells and the like are used. It is also expected to be used for piping for transport and for vibration absorbing piping in parts that receive strong vibrations. Hereinafter, a flexible tube using a metal bellows tube is also simply referred to as a “flexible tube”.

  FIG. 4 is a diagram showing a configuration of a conventional flexible tube. As shown in the figure, straight pipe metal pipes are welded or welded to both ends of the bellows pipe 100 (only one end is shown in the figure) as a base 101 for connection to another pipe. Joined by brazing. Further, a structure 102 for connection to an external pipe line such as a screw or a pipe joint structure is appropriately provided at the outermost end portion of the base 101.

  The joining portion S between the end portions of the bellows tube 100 and the base 101 needs to have sufficient mechanical strength and airtightness so that an internal fluid does not leak from the joining portion. In order to obtain such a joint structure, various welding methods such as tungsten / inert / gas / arc welding (TIG welding), brazing, and the like can be used. A bellows tube having such a base at its end is described in detail in Patent Document 1 and the like.

  In view of the workability of joining the bellows pipe and the base, the outer diameter or inner diameter of the base is at least at the joined portion so that the bellows pipe end can be welded to the outer diameter of the bellows pipe. It is preferable to be within the range of the inner diameter. In the example of FIG. 4, the inner diameter of the base 101 is substantially the same as the inner diameter of the bellows tube, and the outer diameter of the base 101 is enlarged like a flange only on the joint portion S side in accordance with the bellows amplitude of the bellows tube.

However, when the present inventors have examined the joint structure of the base at the end of the bellows pipe as described above, there is a problem that leakage occurs from the joint depending on whether the joint process between the bellows pipe and the base is good or bad. In order to suppress the leakage failure, high quality joining processing is always required, and depending on the purpose of use, discoloration removal processing by welding and a leak test with high leakage detection sensitivity are required. It has been found that there is a problem such as increasing. Furthermore, it has also been found that welding may change the metal structure and cause material deterioration.
WO 2004/023017 Plasticity and processing (Journal of Japan Society for Technology of Plasticity) Vol. 32, No. 366 (1991-7), 818-823

  The problem to be solved by the present invention is to solve the above-mentioned problems existing in the joint structure between a bellows tube and a base, and to provide a flexible tube having a structure capable of suppressing leakage from the boundary portion between the bellows tube and the base And providing a manufacturing method thereof.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has reduced the leakage failure caused by the bonding process failure by eliminating the joint by manufacturing the bellows tube and the base from one metal straight tube. The present invention has been completed by finding out what can be done. That is, the present invention has the following characteristics.
(1) A flexible tube having a metal bellows tube portion, and having a metal tubular portion thicker than the bellows tube portion as a base at at least one tube end thereof,
The base part and the bellows pipe part are formed so as to be continuous with each other from a single metal tubular material having a part that becomes the bellows pipe part and a part that becomes the base part continuously, The flexible tube is characterized in that no joining structure exists at the boundary between the base portion and the bellows tube portion.
(2) The flexible tube according to the above (1), wherein the base part is provided at both pipe end parts of the bellows pipe part.
(3) There is an intermediate tubular part thicker than the bellows pipe part at the intermediate part between both ends of the bellows pipe part,
The bellows tube portion and the intermediate tubular portion are formed so as to be continuous with each other from one metal tubular material having a portion that becomes the bellows tube portion and a portion that becomes the intermediate tubular portion continuously. The flexible tube according to the above (1) or (2), wherein no joining structure is present at the boundary between the bellows tube portion and the intermediate tubular portion.
(4) The flexible tube according to any one of (1) to (3), wherein a connection structure for connecting to an external piping system is provided in the base part.
(5) To manufacture a flexible tube having a metal bellows tube portion and having a metal tubular portion thicker than the bellows tube portion as a base at at least one tube end thereof A method,
One metal tubular material having a portion that becomes a bellows tube portion and a portion that becomes a base portion at least at one end thereof is prepared, and the tubular material is a thickness of a portion that becomes a base portion Is thicker than the thickness of the part that becomes the bellows tube part,
The bellows tube portion is processed into a bellows shape to form a bellows tube portion, thereby obtaining a flexible tube in which the bellows tube portion and the base portion are continuous with each other and no joining structure exists at the boundary between them. The manufacturing method of a flexible tube characterized by the above-mentioned.
(6) The manufacturing method according to the above (5), wherein the tubular material has a portion that becomes a cap portion at both ends of a portion that becomes a bellows tube portion.
(7) Further, the tubular material has an intermediate tubular part thicker than a part to be the bellows pipe part at an intermediate part between both ends of the part to be the bellows pipe part,
Leave the intermediate tubular part as it is and process the bellows pipe part of the part that becomes the bellows pipe part on both sides to make a bellows pipe part, so that the bellows pipe part and the intermediate tubular part are continuous with each other and the boundary between them The manufacturing method according to the above (5) or (6), wherein a flexible tube having no joining structure in the part is obtained.
(8) The manufacturing method according to any one of (5) to (7), wherein the tubular material is formed by cutting and / or drawing.

In the flexible tube of the present invention, the base is thicker than the bellows pipe, but there is no joint structure between the bellows pipe and the base, and both are processed from a single straight pipe material. Since it is a continuous structure, there is no leakage failure, material deterioration, or discoloration due to bonding.
In the manufacturing method of the present invention, the bellows pipe and the base, which are separate parts, are not joined to each other, but a thick part serving as a base and a thin part serving as a bellows pipe are combined into one pipe material. Since the bellows tube and the base are processed into an integrated body using the same, a joining process that requires high technology is omitted, and the cost can be reduced.

Hereinafter, the configuration of the flexible tube according to the present invention will be described with reference to the production method of the present invention.
FIG. 1 is a cross-sectional view schematically showing the flexible tube and its manufacturing process. The tube has a bellows tube portion 1 as shown in FIG. 1A, and has a metallic tubular portion as a cap portion 2 at at least one tube end. The bellows tube portion 1 and the cap portion 2 are formed by processing one metal tubular material illustrated in FIG. 1B, and as shown in FIG. In the boundary portion 3 between the bellows tube portion 1 and the base portion 2, there is no joining structure such as welding or brazing, and both are continuous structures formed from a single metal material. Is connected to one.

To manufacture such a flexible tube, first, a metallic tubular material shown in FIG. 1B is prepared. The tubular material is a single tube having a portion 2a which becomes a cap portion at at least one end portion and a portion 1a which becomes a bellows tube portion in the remaining portion, and a boundary portion between them is It has a continuous metal structure formed as a single element tube, and does not have a joint structure such as welding or brazing.
A flexible tube shown in FIG. 1A is obtained by subjecting the tubular wall portion of the portion 1a to be the bellows tube portion to the bellows processing. This is the manufacturing method according to the present invention.

  In the flexible tube, the base portion 2 may be provided at at least one end portion of the bellows tube portion. However, from the point of eliminating a joining structure such as welding, it is provided at both end portions of the bellows tube portion. It is a preferable aspect that it is provided. In that case, what has a part which becomes a cap part at the both ends of the part used as a bellows pipe part as a tubular material should be prepared, a bellows process should be given, and the said flexible tube should just be obtained.

  In the present invention, the base is thicker than the bellows tube. The base part needs to have sufficient mechanical strength as a structural part related to connection with other pipes, and the bellows pipe part should have a minimum thickness having flexibility and airtightness. In a preferred embodiment, the thickness of the base portion is made thicker than the thickness of the bellows tube portion.

  When making the wall thickness of the base part thicker than the wall thickness of the bellows pipe part, at the stage of the tubular material, either the inner diameter or the outer diameter may be different. For example, in the example of FIG. 2A, the outer diameter of both is the same, and only the inner diameter of the portion 2a that becomes the base portion is made smaller than the inner diameter of the portion 1a that becomes the bellows tube portion. The wall thickness is thicker than the wall thickness of the bellows tube. Further, in the example of FIG. 2B, the thickness of the base part is reduced by reducing the inner diameter and the outer diameter of the part 2a that becomes the base part relative to the part 1a that becomes the bellows pipe part. It is thicker than the wall thickness.

  In order to form a tubular material in which the thickness of the base part is thicker than the thickness of the bellows pipe part as shown in FIGS. 1 (b), 2 (a), and (b), And / or a cutting process (including polishing) on the outer surface, a drawing process using a die in hot or cold conditions (necessary further heat treatment may be appropriately performed), and the like.

  As shown in FIG.1 (b), the boundary part 3 of a tubular raw material has a preferable aspect in which thickness changes smoothly so that the stress concentration by notch may not arise. For example, when the thickness of the base part is 1 mm and the thickness of the bellows tube part is 0.1 mm, the thickness is changed from 1 mm to 0.1 mm in the longitudinal section of about 2 mm to 3 mm. A mode of changing is preferable. The change rate of the wall thickness may be appropriately selected according to the diameter of the tube and the value of the wall thickness.

In the flexible tube according to the present invention obtained by processing the tubular material or the tube material, “no joint structure is present at the boundary portion”, for example, using a metal microscope of about 100 to 400 times, from the base part By observing the metal structure leading to the bellows pipe part through the boundary part, there is no metal structure observed when welding or brazing is performed, and it can be clearly confirmed that both are continuous. .
When the tubular material is formed by cutting, the metal structure from the base part to the bellows pipe part through the boundary part is almost uniform. In addition, when the tubular material is formed by drawing, the metal structure has a difference between the base portion and the bellows tube portion due to compression applied by the die, etc., but continuously changes at the boundary portion. Become.
On the other hand, when two different parts (same metal materials as each other) are joined, direct welding is performed, and welding using a welding material or brazing material made of the same metal material is performed. Even if a sufficient heat treatment is applied, all the parts are equal in terms of material composition, but the metal structure is clearly discontinuous at the boundary.

The base part is a straight tube having a constant wall thickness in a normal mode, but may be an arbitrary curved tube depending on the application, and the wall thickness may be changed.
Moreover, what is necessary is just to provide suitably all structures for connection with an external pipeline, such as a screw and a pipe joint structure, as shown in FIG. Such a structure for connection to the outside may be added to the base part by welding, brazing or the like, or a female screw or groove directly processed on the outer periphery or inner periphery of the base part. It may be.

For the method itself of processing the bellows tube portion of the tubular material into a bellows shape, a known bellows tube processing technique may be referred to. For example, a hydraulic molding method, an elastomer molding method, a continuous die molding method Etc. Details of these processing methods are described in Non-Patent Document 1 described above.
Furthermore, as shown in the above-mentioned Patent Document 1, the processed bellows-like portion may be further compressed in the longitudinal direction to form a bellows pipe portion that can withstand high pressure inside.

A preferred embodiment of the tubular material is a straight pipe (however, since it has a part that becomes a base part and a part that becomes a bellows pipe part, the wall thickness varies depending on the part), it is an arbitrary curved pipe depending on the application. Also good.
The material of the tubular material, that is, the material of the flexible tube is not particularly limited, but a material having good corrosion resistance and high mechanical strength is preferable. For example, conventional materials such as stainless steel, titanium, aluminum, copper, nickel, etc. Examples include general materials used for metal bellows. Further, depending on the application, silver, platinum, gold, various special alloys having heat resistance and corrosion resistance (for example, Hastelloy (registered trademark), Inconel (registered trademark)), and the like may be used.

Bellows pipe length (natural length), wall thickness, bellows pitch, peak outer diameter (maximum outer diameter), valley outer diameter, bellows average diameter, valley inner diameter (minimum inner diameter), bellows dimensions, etc. The specifications are not limited, and may be determined according to the use and request.
Examples of general numerical values are given below, but they do not limit the present invention.
The bellows tube thickness is about 0.1 mm to 0.3 mm, the bellows pitch is about 0.5 mm to 5 mm, the mountain outer diameter (maximum outer diameter) is about 5 mm to 50 mm, and the valley outer diameter. Is about 3 mm to 40 mm. Even for the bellows having the same thickness and pitch, an appropriate dimension may be selected according to the application location, for example, 10 mm to 10000 mm.

The thickness, the inner diameter (outer diameter), and the length of the base part may be appropriately determined according to the application and requirements and so as to conform to the dimensions of the bellows pipe part.
Examples of general numerical values are given below, but they do not limit the present invention.
The thickness of the base part is about 1 mm to 5 mm, the inner diameter is about 3 mm to 40 mm, and the length is about 10 mm to 100 mm.

There is no limitation on the dimensions of the bellows tube part and the base part, but the point that both parts are formed from a single tubular material, and the parts with different thicknesses are formed on a single tubular material In view of this, there are preferred combinations.
For example, when the thickness t2 of the base part is set to be equal to or greater than the thickness t1 of the bellows pipe part, the thickness t2 of the base part is more than about 1 times the wall thickness t1 of the bellows pipe part, and about 20 times or less. From the point of processing the tubular material, it is preferable to set it to more than 1 time and about 10 times or less. In addition, when the numerical value of thickness changes, since the ratio of thickness of both may not be the same, the combination of preferable thickness should just be selected suitably according to each case.
Moreover, the aspect which makes the internal diameter of a nozzle | cap | die part and the internal diameter of a bellows pipe part the same dimension is a preferable aspect with which resistance with respect to the flow of the fluid in a pipe | tube becomes small.

In the flexible tube of the present invention, in addition to the base portion, as shown in FIG. 3, even if an intermediate tubular portion 4 thicker than the bellows tube portion is present in the intermediate portion of the bellows tube portion 1. Good. The intermediate portion may be an arbitrary position between both ends of the bellows pipe portion as well as the central portion.
Also in this embodiment, the boundary portion 5 between the intermediate tubular portion 4 and the bellows tube portion 1 does not have a joining structure as in the case of the cap portion, and the bellows tube portion and the intermediate tubular portion are not shown in FIG. ) Are formed so as to be continuous with each other from one metal tubular material as exemplified in FIG.
Such an intermediate tubular portion is useful when the flexible tube is directly supported using a support member base or a holding device. That is, the bellows tube portion is thin and may be easily deformed when a force for supporting or holding is applied, but the intermediate tubular portion is a thick tube and is difficult to deform. Therefore, if such an intermediate tubular portion is used as a portion for applying a force for supporting or holding, the flexible tube can be supported or held more firmly and preferably.
In order to manufacture the flexible tube having the above-described aspect, as shown in FIG. 3 (b), at the stage of the tubular material, the intermediate portion of the portion 1a that becomes the bellows tube portion is more than the portion that becomes the bellows tube portion. Alternatively, a thick intermediate tubular portion 4a may be provided, and the intermediate tubular portion 4a may be left as it is, and the tube walls of the portions that become the bellows tube portions on both sides thereof may be processed into a bellows shape to form a bellows tube portion.

As for the thickness of the intermediate tubular portion, at the stage of the tubular material, as in the case of the above-described base portion, a difference may be provided in either of the inner diameter and the outer diameter (FIG. 1 (b), FIG. 2 (a)). FIG. 2 (b)).
In addition, in order to form a tubular material in which the thickness of the intermediate tubular portion is greater than the thickness of the bellows tube portion, cutting (including polishing) processing, hot or cold on the inner surface and / or outer surface of the tube And drawing using a die (necessary further heat treatment may be performed as appropriate).
In addition, the boundary portion 5 between the intermediate tubular portion 4 and the bellows tube portion 1 preferably has a mode in which the wall thickness changes smoothly so that stress concentration due to the notch does not occur as in the case of the cap portion. The change rate of the wall thickness may be appropriately selected according to the diameter of the tube and the value of the wall thickness.

In this example, a flexible tube according to the present invention was manufactured by processing a tubular material having a base at both ends of a bellows tube portion by cutting, and then applying bellows processing to the bellows tube portion.
Material of raw tube for forming a tubular material: SUS304.
The thickness of the tube (= the thickness of the base): 1 mm.
The outer diameter of the raw tube (= the outer diameter of the base): 10 mm.
Total length of the raw tube: 450 mm.
As shown in FIG.1 (b), the outer side of the raw pipe was cut with a lathe, and the outer diameter of the part which becomes a bellows pipe part was 8.3 mm (inner diameter was 8 mm). That is, the thickness of the portion that becomes the bellows tube portion is 0.15 mm. Moreover, each effective length of the part used as the cap part of both ends was 40 mm, and 2.5 mm was ensured as a boundary part from which an outer diameter changes continuously. As a result, the length of the portion that becomes the bellows tube portion is about 365 mm.

  After inflating the bellows tube portion (having an outer diameter of 8.3 mm as shown in FIG. 1 (b)) to an outer diameter of 10 mm, the bellows tube is subjected to bellows processing, and the tube outer diameter of the peak portion A flexible tube according to the present invention was obtained with a bellows tube portion having a tube inner diameter of 10.8 mm, a valley tube inner diameter of 7.6 mm, a pitch of 2.4 mm, and an effective bellows length of 230 mm.

  When observing the flexible tube obtained by the above processing, it was confirmed that there was no cause for the occurrence of a leak because there was no joint between the bellows tube part and the base part, and the leak test could be omitted. . Moreover, since the boundary part of a bellows pipe part and a nozzle | cap | die part has not received the thermal influence by welding etc., it was confirmed that there is no deterioration of material in this part.

As described above, in the flexible tube of the present invention, the bellows tube and the base are formed directly from a single tube without a joint structure. Therefore, there is no need for techniques related to welding and brazing, and there is no fundamentally poor bonding, so there is no material degradation due to changes in the metal structure, no leakage defects due to poor bonding, and airtightness. high. Further, as a result of the difficult joining process being omitted, the processing cost can be reduced.
In addition to general piping applications, the flexible tube is used for piping in facilities and equipment that require a high degree of sealing, such as semiconductor manufacturing equipment, nuclear power generation equipment, aerospace equipment and equipment, and hydrogen fuel cells. It is also useful as a piping application in facilities and devices that handle high-pressure fluids, and as a vibration-absorbing piping application in parts that receive strong vibrations.

It is sectional drawing which shows typically the change of the product in the process of the structure of the flexible tube by this invention, and the manufacturing method by this invention. In the drawing, the cross section of the tube is shown only on one side (upper side in the figure) of the center line, and the lower side is omitted. The same applies to FIGS. 2 and 3. It is sectional drawing which showed the aspect of the tubular raw material in the case of making thickness of a nozzle | cap | die part thicker than the thickness of a bellows pipe part. It is the fragmentary sectional view which showed the aspect by which the tubular part was provided in the intermediate part of the bellows pipe part. The end cap portion is not shown. It is the fragmentary sectional view which showed the structure of the conventional flexible tube typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bellows pipe part 1a The part used as a bellows pipe part 2 Base part 2a The part used as a base part 3 Boundary part

Claims (8)

A flexible tube having a metal bellows tube portion, and having a metal tubular portion thicker than the bellows tube portion as a base at at least one tube end thereof,
The base part and the bellows pipe part are formed so as to be continuous with each other from one metal tubular material having a part that becomes the bellows pipe part and a part that becomes the base part continuously, The flexible tube is characterized in that no joining structure exists at the boundary between the base portion and the bellows tube portion.   The flexible tube according to claim 1, wherein the base part is provided at both pipe end parts of the bellows pipe part. In the middle part between both ends of the bellows pipe part, there is an intermediate tubular part thicker than the bellows pipe part,
The bellows tube portion and the intermediate tubular portion are formed so as to be continuous with each other from one metal tubular material having a portion that becomes the bellows tube portion and a portion that becomes the intermediate tubular portion continuously. The flexible tube according to claim 1, wherein no joining structure is present at the boundary between the bellows tube portion and the intermediate tubular portion.   The flexible tube in any one of Claims 1-3 by which the structure for a connection for connecting with an external piping system is provided in the nozzle | cap | die part. This is a method for producing a flexible tube having a metal bellows tube portion and having a metal tubular portion thicker than the bellows tube portion at the end of at least one tube as a base portion. And
One metal tubular material having a portion that becomes a bellows tube portion and a portion that becomes a base portion at least at one end thereof is prepared, and the tubular material is a thickness of a portion that becomes a base portion Is thicker than the thickness of the part that becomes the bellows tube part,
The bellows tube portion is processed into a bellows shape to form a bellows tube portion, thereby obtaining a flexible tube in which the bellows tube portion and the base portion are continuous with each other and no joining structure exists at the boundary between them. The manufacturing method of a flexible tube characterized by the above-mentioned.   The manufacturing method according to claim 5, wherein the tubular material has a portion that becomes a cap portion at both ends of a portion that becomes a bellows tube portion. Furthermore, the tubular material has an intermediate tubular portion that is thicker than the portion that becomes the bellows tube portion at the intermediate portion between both ends of the portion that becomes the bellows tube portion,
Leave the intermediate tubular part as it is and process the bellows pipe part of the part that becomes the bellows pipe part on both sides to make a bellows pipe part, so that the bellows pipe part and the intermediate tubular part are continuous with each other and the boundary between them The manufacturing method of Claim 5 or 6 which obtains the flexible tube in which a junction structure does not exist in a part.   The manufacturing method according to claim 5, wherein the tubular material is formed by cutting and / or drawing.

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