JP3667720B2 - Flexible tube joining method - Google Patents

Description

【００１５】
解析の結果を以下の表２に示す。

【００１６】
この表２に示すように、本発明の組み合わせチューブは、従来例の組み合わせチューブに比べて長さが短いにも拘わらず、従来例の組み合わせチューブよりも最大応力が低かった。
【００１７】
【発明の効果】
以上の説明から明らかなように、本発明に係る接合方法は、従来の接合方法に比べて数々の利点を有する。具体的に、（１）本発明の接合方法によれば、フレキシブルチューブと別のチューブとの間に溶融したろう材が隙間無く薄く広がるため、従来の接合方法よりも高い接合強度が得られる。また、同一荷重条件のもとでは、接合部近傍にあるフレキシブルチューブ部分に発生する応力が従来の接合方法に比べて一段と小さくなる。そのため、配管系の中で特に過酷な条件の場所（振動の発生する箇所、配管系の中で無理な力が作用する箇所）で使用した場合でも、従来の接合方法によって接合された組み合わせチューブに比べ、本発明の接合方法によって接合された組み合わせチューブは、フレキシブルチューブに環状段部を形成すると共にこの環状段部に別のチューブを嵌合する特殊な接合方法及び接合機構によってより応力集中を低下させることができ、そのためにフレキシブルチューブの金属疲労に対する耐久性が向上する。また、（２）従来の接合方法は、加熱温度、ろう材の差し量等の管理が難しく、それらの管理状態によって品質が大きく左右されることから熟練を要するのに対し、本発明の接合方法は単に加工されたフレキシブルチューブの環状段部にろう材を配置して加熱するだけであるために、熟練を要することなく均一な品質の接合が得られる。さらに、（３）従来の接合方法ではフレキシブルチューブと別のチューブとの芯合わせが難しいのに対し、本発明の接合方法ではフレキシブルチューブの環状段部に別のチューブを差し込むだけで芯合わせされる。
【図面の簡単な説明】
【図１】 フレキシブルチューブと別のチューブ（円管）を本発明の接合方法により接合した組み合わせチューブの部分断面図。
【図２】 本発明に係る接合方法のプロセスを示すチューブの部分断面図〔図２（ａ）〜（ｅ）〕。
【図３】 フレキシブルチューブの端部に環状フランジを加工する方法を示す部分断面図〔図３（ａ）、（ｂ）〕。
【図４】 フレキシブルチューブに環状段部を加工する他の方法を示す部分断面図。
【図５】 フレキシブルチューブと別のチューブ（円管）を従来の接合方法により接合した組み合わせチューブの部分断面図。
【符号の説明】
１０：フレキシブルチューブ
１２：別のチューブ
１４：大径部
１６：小径部
１８：逆テーパ部
４０：環状段部
４６：ろう材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of joining a flexible tube and another tube (tube).
[0002]
[Prior art]
Conventionally, as shown in FIG. 5, when another tube 106 (for example, a circular tube) is joined to the end of the flexible tube 100 in which the large-diameter portions 102 and the small-diameter portions 104 are alternately formed, And the end of another tube 106 are abutted, and the abutting portion is joined by brazing 108 by inserting a brazing material into the abutting portion while heating the abutting portion with a burner.
[0003]
[Problems to be solved by the invention]
However, such a flexible tube 100 is often used in a place where vibration is likely to occur or where an excessive force is generated in the piping system. For this reason, the joint between the flexible tube 100 and another tube 106 is used. And stress tends to concentrate in the vicinity. Therefore, another bonding method has been desired that has higher strength than the brazing 108 as described above and that can reduce the stress generated in the flexible tube 100 as much as possible.
[0004]
Moreover, it is difficult to hold | maintain the flexible tube 100 and another tube 106 coaxially by the above-mentioned joining method. Furthermore, the gap generated on the abutment surface between the flexible tube 100 and another tube 106 varies depending on the location, and this affects the outcome of the brazing 108. The brazing 108 requires skill and must carefully manage the heating time and the heating temperature. As a result, brazing takes a long time and productivity is poor.
[0005]
[Means for Solving the Problems]
In order to eliminate such problems, the flexible tube joining method according to the present invention is a method of joining another tube to at least one end of a flexible tube in which a large diameter portion and a small diameter portion are alternately formed along the central axis. Consists of the following steps.
(A) A step of forming one end of the flexible tube in a reverse tapered shape so that the diameter gradually increases toward the outside.
(B) A first annular flange portion extending radially outward from one end of the flexible tube processed into a reverse taper shape, and substantially parallel to the central axis from the radially outer end of the first annular flange portion And an annular step having a second annular flange portion extending outward.
(C) The process of arrange | positioning a brazing material to an annular step part.
(D) A step of fitting an end portion of another tube to the annular step portion on which the brazing material is arranged.
(E) A step of heating the brazing material to join the flexible tube and another tube.
[0006]
The other joining method of this invention consists of the following processes.
(A) The process of forming the annular flange part extended toward radial direction outer side at the end of a flexible tube.
(B) a first annular flange portion extending radially outward in the annular flange, and a second extending substantially parallel to the center axis and outward from a radially outer end of the first annular flange portion; The process of processing into the annular step part which has an annular flange part.
(C) The process of arrange | positioning a brazing material to an annular step part.
(D) A step of fitting an end portion of another tube to the annular step portion on which the brazing material is arranged.
(E) A step of heating the brazing material to join the flexible tube and another tube.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of embodiments of a flexible tube joining method according to the present invention will be described with reference to the accompanying drawings. First, FIG. 1 shows a flexible tube 10 and another tube 12 joined using the flexible tube joining method according to the present invention. The flexible tube 10 is obtained by alternately and continuously forming large diameter portions 14 and small diameter portions 16 in a circular tube. Another tube 12 is a circular tube. The material of the flexible tube 10 and the other tube 12 is arbitrary, and various metals (for example, stainless steel, iron, copper, and other alloys) are used.
[0008]
A method for joining the flexible tube 10 and another tube 12 is shown in FIGS. 2 (a) to 2 (e). The joining method will be described. First, as shown in FIG. 2A, the end of the flexible tube 10 is processed into a reverse taper shape toward the outside (in other words, a taper shape toward the inside), and then reverse taper. Part 18 is formed. The reverse taper portion 18 can be processed by various methods. As an example, as shown in FIG. 3A, first, the flexible tube 10 is cut at its small diameter portion 16a. Next, an annular mold 20 is disposed between the outermost large-diameter portion 14a adjacent to the cut small-diameter portion 16a and the inner large-diameter portion 16b adjacent thereto, and is opposed to the cut small-diameter portion 16a. Then, another mold 22 is arranged, and the molds 20 and 22 are brought close to each other to crush the outer large-diameter portion 14a. Subsequently, as shown in FIG. 3B, a die 24 having a reverse tapered surface is applied from the outside toward the crushed large-diameter portion 14a, and the crushed large-diameter portion 14a is adjacent to the large-diameter portion 14a. A wedge-shaped annular die 26 is pushed into the diameter portion 14b, and the large-diameter portion 16 is pressed by these two dies 24 and 26. As a result, the large diameter portion 14a sandwiched between the dies 24 and 26 is processed into the reverse tapered portion 18 in FIG. The annular molds 20 and 26 inserted between the two adjacent large-diameter portions 14a and 14b are composed of a plurality of divided mold parts.
[0009]
Returning to FIG. 2, as shown in FIG. 2B, the reverse tapered portion 18 is processed again by the two molds 30 and 32 with respect to the flexible tube 10 in which the reverse tapered portion 18 is processed. At this time, the first die 30 disposed to face the inner surface of the reverse taper portion 18 has a corner portion 34 at the outer peripheral end facing the reverse taper portion 18. On the other hand, the second mold 32 facing the outer surface of the reverse tapered portion 18 has a stepped portion 36 having a shape corresponding to the corner portion 34 of the first mold 30. Similarly to the molds 20 and 26 described above, the second mold 32 includes a plurality of divided mold parts. Then, the reverse taper portion 18 is pressed from the inner surface and the outer surface by the first die 30 and the second die 32, and the annular step portion 40 is formed at the end portion of the flexible tube 10. The annular step portion 40 includes a first annular flange portion 42 extending radially outward from the central axis X, and an outer peripheral end portion of the first annular flange 42 substantially parallel to the central axis X and outward. It consists of a second annular flange portion 44 that extends. During this pressing, the plurality of mold parts constituting the second mold 32 are collected from the radially outer side toward the inner side toward the central axis X, and the reverse taper portion is formed between the first mold 30 and the first mold 30. 18 is sandwiched and deformed.
[0010]
Next, as shown in FIG. 2 (d), a brazing material 46 is disposed on the inner surface of the annular stepped portion 40. The material of the brazing material 46 is preferably selected depending on the material of the flexible tube 10 and the other tube 12. For example, when the flexible tube 10 is stainless steel and the other tube 12 is copper, silver brazing is used. Subsequently, the end of another tube 12 is inserted into the annular step 40, heat 50 is applied to the brazing material 46 by a heater 48 (preferably a high frequency induction heating device), and the brazing material 46 is removed from the outer periphery of the annular step 40. Heat to melt. At this time, the flexible tube 10 and another tube 12 apply a force in the opposite direction. Moreover, in FIG.2 (d), although the flexible tube 10 and another tube 12 are orient | assigned to the horizontal direction, it is preferable to make both face up and down at the time of a heating. As a result, as shown in FIG. 2 (e), the molten brazing material 46 spreads uniformly in the gap between the flexible tube 10 and the other tube 12 by capillary action, and strongly bonds both.
[0011]
In the above description, in particular, as shown in FIG. 3A, the end of the flexible tube 10 is cut by the small diameter portion 16a, and then the adjacent large diameter portion 14a is crushed to thereby form the reverse tapered portion 18 in two. Heavy structure. However, the reverse tapered portion and the annular stepped portion may have a single structure by cutting the end portion of the flexible tube 10 in the vicinity of the maximum outer diameter portion of the large diameter portion 14.
[0012]
Moreover, the processing method which forms the annular step part 40 in the edge part of the flexible tube 10 is not restricted to the above-mentioned thing. For example, FIG. 4 shows another processing method of the annular step portion 40, in which an annular flange 52 that extends radially outward is first formed at the end of the flexible tube 10. The annular flange 52 can be formed by the method described with reference to FIG. Next, a cylindrical or columnar first die 54 is applied to the outer surface of the annular flange 52. The mold 54 is formed with a concave stepped portion 56 by cutting off the outer peripheral corner. In addition, an annular second mold 58 composed of a plurality of mold parts is disposed outside the flexible tube 10. The second mold 58 includes an inner annular protrusion 60 that enters between the annular flange 52 and the large-diameter portion 16b adjacent thereto. Then, the first die 54 and the second die 58 are moved in the opposing direction along the central axis X, and the outer peripheral portion of the annular flange 52 facing the annular protrusion 60 is bent outward at a substantially right angle to form an annular shape. A step (see FIG. 2) is formed.
[0013]
A predetermined amount (center) of a combination tube in which a circular tube is bonded to both ends of the flexible tube by the bonding method of the present invention and a combination tube in which a circular tube is bonded to both ends of the flexible tube by a conventional bonding method (brazing using a gas burner) The amount of stress generated in the weakest part of the flexible tube (near the joint with the circular tube) when a deformation of 5 mm in the axial direction and 1 mm in the direction orthogonal to the central axis) is applied to the finite element. Analyzed by the method. The conditions of the model used for the analysis are as shown in Table 1 below. Both brazing materials were the same.
[0014]

[0015]
The results of the analysis are shown in Table 2 below.

[0016]
As shown in Table 2, the combined tube of the present invention had a lower maximum stress than the conventional combined tube, although the length was shorter than that of the conventional combined tube.
[0017]
【The invention's effect】
As is apparent from the above description, the bonding method according to the present invention has a number of advantages over the conventional bonding method. Specifically, (1) According to the bonding method of the present invention, since the molten brazing material spreads thinly between the flexible tube and another tube without any gap, higher bonding strength than that of the conventional bonding method can be obtained. Further, under the same load condition, the stress generated in the flexible tube portion in the vicinity of the joint is much smaller than that of the conventional joining method. Therefore, even when used in places with particularly severe conditions in the piping system (locations where vibrations occur or where excessive force acts in the piping system), the combined tubes joined by the conventional joining method In comparison, the combined tube joined by the joining method of the present invention reduces the stress concentration due to a special joining method and joining mechanism in which an annular step is formed on the flexible tube and another tube is fitted to the annular step. Therefore, the durability of the flexible tube against metal fatigue is improved. In addition, (2) the conventional joining method is difficult to manage such as the heating temperature and the amount of brazing filler metal, and skill is required because the quality is greatly affected by the management state, whereas the joining method of the present invention Since the brazing material is simply placed and heated on the annular step portion of the processed flexible tube, uniform quality bonding can be obtained without requiring skill. Furthermore, (3) the conventional joining method makes it difficult to align the flexible tube with another tube, whereas the joining method of the present invention allows the centering by simply inserting another tube into the annular step of the flexible tube. .
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of a combination tube in which a flexible tube and another tube (circular tube) are joined by the joining method of the present invention.
FIG. 2 is a partial cross-sectional view of a tube showing a process of a joining method according to the present invention (FIGS. 2A to 2E).
FIG. 3 is a partial cross-sectional view (FIGS. 3A and 3B) showing a method of processing an annular flange at the end of a flexible tube.
FIG. 4 is a partial cross-sectional view showing another method for processing an annular stepped portion in a flexible tube.
FIG. 5 is a partial cross-sectional view of a combination tube in which a flexible tube and another tube (circular tube) are joined by a conventional joining method.
[Explanation of symbols]
10: Flexible tube 12: Another tube 14: Large diameter portion 16: Small diameter portion 18: Reverse taper portion 40: Annular step portion 46: Brazing material

Claims (2)

A method of joining another tube to at least one end of a flexible tube in which a large diameter portion and a small diameter portion are alternately formed along a central axis,
Forming one end of the flexible tube into a reverse taper shape so that the diameter gradually increases toward the outside;
One end of the flexible tube processed into the reverse tapered shape has a first annular flange portion extending radially outward, and substantially parallel to the central axis from the radially outer end of the first annular flange portion, and Processing into an annular step having a second annular flange portion extending outwardly;
Arranging a brazing material on the annular step;
Fitting the end of another tube to the annular step where the brazing material is disposed;
A method of joining a flexible tube, comprising: heating the brazing material to join the flexible tube and another tube. A method of joining another tube to at least one end of a flexible tube in which a large diameter portion and a small diameter portion are alternately formed along a central axis,
Forming an annular flange extending radially outward at one end of the flexible tube;
A first annular flange portion extending radially outward from the annular flange, and a second annular portion extending substantially parallel to the central axis and outward from a radially outer end of the first annular flange portion Processing into an annular step having a flange portion;
Arranging a brazing material on the annular step;
Fitting the end of another tube to the annular step where the brazing material is disposed;
A method of joining a flexible tube, comprising: heating the brazing material to join the flexible tube and another tube.

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