JP2005320995A - Connecting structure and connecting method of metal pipe and connecting object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure, attaining high air tightness, liquid tightness and connecting stability of a metal pipe and a connecting object, and provide a connecting method, performing connection with a small number of parts and work processes by simplified manufacturing technique. <P>SOLUTION: The tip edge of the metal pipe 1 is doubly bent inward to form a funnel-like double flared part 2 gradually increased in width as it goes outward. The double flared part 2 is inserted in a cylindrical connecting wall 7 provided in the connecting object 5, and the funnel-like inner peripheral surface 3 of the double flared part 2 is abutted on the funnel-like abutting surface 6 of the connecting object 5. The connecting wall 7 is caulked to the outer peripheral surface 4 of the double flared part 2 to fix the double flare part 2 by caulking, whereby the funnel-like inner peripheral surface 3 of the double flared part 2 and the funnel-like abutting surface 6 of the connecting object 5 are made to closely adhere to each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、自動車、各種の機械装置等に給油、給気等の供給路として用いられる金属管とその接続対象物との接続構造及びその接続方法に係るものである。   The present invention relates to a connection structure between a metal pipe used as a supply path for oil supply, air supply, and the like to an automobile, various mechanical devices and the like, and a connection method thereof.

従来、自動車、各種の機械装置等に給油、給気等の供給路として用いられる金属管と、管継手等の金属管の接続対象物とを接続する手段として、特許文献１、２に示す如く、金属管を、管継手等の接続対象物にナットにより接続固定するものが存在した。これらの発明又は考案では、二重巻き金属管の先端を、内側に二重に折り曲げて外方幅広の漏斗状のダブルフレア部を設けたり、或いは金属管の先端を外方に膨出させてＩＳＯフレア部やブッリッジフレア部を設け、この金属管の接続対象物に、前記ダブルフレア部の内周面や、ＩＳＯフレア部又はブリッジフレア部の先端外周面を当接させる突当部を形成する。そして、金属管の外周にナットを装着し、このナットを接続対象物に螺着する事により、ナットと当接部とで前記ダブルフレア部、ＩＳＯフレア部又はブリッジフレア部を強く締め付ける事により、金属管と接続対象物とを接続固定するとともに、ナットにより当接部にダブルフレア部の内周面又はＩＳＯフレア部若しくはブリッジフレア部の外周面を強く押し付けて、接続構造に気密性を持たせようとするものである。尚、前記金属管の先端へのダブルフレア部、ＩＳＯフレア部又はブリッジフレア部の形成方法は、特許文献６〜８の如き方法が知られている。   Conventionally, as shown in Patent Documents 1 and 2, as means for connecting a metal pipe used as a supply path for oil supply, air supply, etc. to automobiles, various mechanical devices, etc., and a metal pipe connection object such as a pipe joint. In some cases, a metal pipe is connected and fixed to a connection object such as a pipe joint with a nut. In these inventions or devices, the end of the double-wrapped metal tube is folded inward twice to provide a funnel-shaped double flare portion that is wide outward, or the tip of the metal tube is bulged outward. An ISO flare part and a bridging flare part are provided, and an abutting part for contacting the inner peripheral surface of the double flare part and the outer peripheral surface of the tip end of the ISO flare part or the bridge flare part is formed on the connection object of the metal tube. To do. And, by attaching a nut to the outer periphery of the metal tube and screwing this nut to the connection object, by tightening the double flare part, ISO flare part or bridge flare part with the nut and the contact part, The metal tube and the connection object are connected and fixed, and the inner peripheral surface of the double flare portion or the outer peripheral surface of the ISO flare portion or the bridge flare portion is strongly pressed against the abutting portion with a nut to make the connection structure airtight. It is about to try. As methods for forming a double flare portion, an ISO flare portion, or a bridge flare portion on the tip of the metal tube, methods as described in Patent Documents 6 to 8 are known.

また、他の異なる接続手段として、特許文献３〜４では、金属管に軸方向への圧縮力を加えて金属管の先端外周にバルジ部を突出形成し、この金属管の先端及びバルジ部を挿入可能な円筒状の接続壁を接続対象物に突出形成している。また、接続対象物には、金属管の先端縁を突き当てるための当接段部を管軸方向垂直に形成している。そして、接続壁内に金属管の先端及びバルジ部を挿入して、金属管の先端縁を当接段部に突き当てた後、カシメ加工により接続壁をバルジ部の外周面にカシメ固定する事で、金属管と接続対象物とを接続固定している。尚、バルジ部は、特許文献３では、接続壁内への金属管の挿入後に行っており、特許文献４、５では、金属管への挿入前に金属管を加工して形成している。更に、特許文献４、５では、接続部分の気密性を高めるため、金属管の外周と接続壁との内周との間に、シール部材としてＯリングを介在させている。
特開昭５８−９３１０号公報 実用新案登録第２５４０５７１号公報 特開平９−２６０６４号公報 特開２００３−１３０２６２号公報 特開２００３−２６２２９１号公報 特開昭５９−１７３１３号公報 特開昭６０−１８２６０号公報 特開昭６３−１７５３７号公報 As another different connection means, in Patent Documents 3 to 4, an axial compressive force is applied to the metal tube to form a bulge portion on the outer periphery of the tip of the metal tube. A cylindrical connection wall that can be inserted projects from the connection object. Further, a contact step for abutting the leading edge of the metal tube is formed on the connection object vertically in the tube axis direction. Then, after inserting the tip and bulge part of the metal tube into the connecting wall and abutting the leading edge of the metal tube against the contact step part, the connecting wall is caulked and fixed to the outer peripheral surface of the bulge part. Thus, the metal tube and the connection object are connected and fixed. In Patent Document 3, the bulge portion is formed after the metal tube is inserted into the connection wall, and in Patent Documents 4 and 5, the metal tube is processed before being inserted into the metal tube. Further, in Patent Documents 4 and 5, an O-ring is interposed as a seal member between the outer periphery of the metal tube and the inner periphery of the connection wall in order to improve the airtightness of the connection portion.
JP 58-9310 A Utility Model Registration No. 2540571 JP-A-9-26064 JP 2003-130262 A JP 2003-262291 A JP 59-17313 A Japanese Patent Laid-Open No. 60-18260 JP-A-63-17537

しかしながら、上記特許文献１、２では、金属管と接続対象物との接続にナットを使用するため、締め付けや部品組み付けの手間や部品点数の増加を招くとともに、接続対象物側にナットを装着するためのスペースを確保する必要があり、嵩張るものとなっていた。更には、ナットの締め付け時に於いても、工具を操作するスペースを必要とし、狭い空間等での作業が行いにくいものであった。また、ＩＳＯフレア部やブリッジフレア部では、ナットの押圧力により、軸方向に押し縮められ、不均一に変形する事があり、気密性が低下する虞があった。   However, in Patent Documents 1 and 2 described above, a nut is used to connect the metal tube and the connection object, so that tightening and parts assembling work and the number of parts are increased, and the nut is attached to the connection object side. It was necessary to secure a space for this, and it was bulky. Furthermore, even when the nut is tightened, a space for operating the tool is required, and it is difficult to work in a narrow space. Further, the ISO flare portion and the bridge flare portion are compressed in the axial direction by the pressing force of the nut, and may be deformed unevenly, which may reduce the airtightness.

また、特許文献３〜５では、金属管の先端縁を垂直な当接段部に突き当てているだけなので、部品の組み付けを厳密に行う必要があって、作業が面倒であるとともに、接続後は固定安定性が悪く、液体や気体の流動圧又は車体の振動等により、接続部分の気密性を損なう虞があった。また、気密性を高めるためにシール部材を使用する必要があり、部品点数を多くしてコスト高となる可能性があった。   Moreover, in patent documents 3-5, since the front-end edge of a metal tube is only abutted on the vertical contact | abutting step part, it is necessary to carry out the assembly | attachment of parts strictly, and work is troublesome, and after connection The fixing stability is poor, and there is a possibility that the airtightness of the connection portion may be impaired due to fluid pressure of liquid or gas or vibration of the vehicle body. In addition, it is necessary to use a seal member in order to improve airtightness, and there is a possibility that the number of parts is increased and the cost is increased.

本発明は上述の如き課題を解決しようとするものであって、金属管とその接続対象物との接続に於いて、気密性又は液密性と固定安定性に優れる接続構造を得るとともに、多くの部品点数や製作の手間、更には高精度な寸法合わせ等を必要とせず、簡易な接続方法で行う事を可能とするものである。そして、流体の流動や振動等の刺激による気密性、液密性の低下を良好に防止可能な耐久性に優れる製品を得るものである。また、金属管と接続対象物との接続構造をコンパクトなものとし、設置スペースを取らず、更には接続作業に於いても広いスペースを使用する事のないものとし、収納効率や作業効率を向上させるものである。   The present invention is intended to solve the above-described problems, and in connection between a metal tube and an object to be connected, a connection structure excellent in airtightness or liquid-tightness and fixing stability is obtained. Therefore, it is possible to carry out by a simple connection method without the need for the number of parts, the labor of manufacturing, and the highly accurate dimensional alignment. And the product which is excellent in the durability which can prevent the fall of airtightness by the stimulation of fluid flow, vibration, etc., and liquid tightness can be obtained favorably. In addition, the connection structure between the metal tube and the object to be connected is made compact so that it does not take up installation space and does not use a large space for connection work, improving storage efficiency and work efficiency. It is something to be made.

本発明は上述の如き課題を解決するため、第１の発明は、金属管の先端縁側を内側に二重に折り曲げて外方幅広の漏斗状のダブルフレア部を形成し、このダブルフレア部を、接続対象物に設けた円筒状の接続壁内に挿入するとともに、ダブルフレア部の漏斗状の内周面を接続対象物の漏斗状の突当面に当接し、ダブルルフレア部の外周面に接続壁をカシメてダブルフレア部をカシメ固定する事により、ダブルフレア部の漏斗状の内周面と接続対象物の漏斗状の突当面とを密着させて成る、金属管とその接続対象物との接続構造である。   In order to solve the above-described problems, the first invention forms a funnel-shaped double flare portion having a wide outer side by bending the tip edge side of the metal tube inwardly, and this double flare portion is , Insert into the cylindrical connection wall provided on the connection object, and the funnel-shaped inner peripheral surface of the double flare part abuts on the funnel-shaped abutting surface of the connection object, to the outer peripheral surface of the double flare part By caulking the connecting wall and fixing the double flare part by caulking, the metal pipe and its connection object are formed by bringing the funnel-shaped inner peripheral surface of the double flare part into close contact with the funnel-shaped abutting surface of the connection object. This is a connection structure.

また、第２の発明は、金属管の先端縁を、内側に二重に折り曲げて外方幅広の漏斗状のダブルフレア部を形成する工程と、この金属管を接続する接続対象物に、ダブルフレア部の漏斗状の内周面を当接する漏斗状の突当面を形成するとともに、この漏斗状の突当面の外周に、ダブルフレア部の外周面を被覆可能な接続壁を円筒状に突出形成する工程と、この接続対象物の接続壁内に金属管のダブルフレア部を挿入し、その漏斗状の内周面を突当面に当接する工程と、前記円筒状の接続壁をカシメてダブルフレア部をカシメ固定する事により、ダブルフレア部の漏斗状の内周面と接続対象物の漏斗状の突当面とを密着させて金属管と接続対象物とを接続固定する工程とから成る、金属管とその接続対象物との接続方法である。   In addition, the second invention includes a step of forming a double-flared portion having a wide outer side by bending the tip edge of the metal tube inwardly, and a connection object for connecting the metal tube to a double object. A funnel-shaped abutting surface that contacts the funnel-shaped inner peripheral surface of the flared portion is formed, and a connection wall that can cover the outer peripheral surface of the double-flared portion is formed in a cylindrical shape on the outer periphery of the funnel-shaped abutting surface A step of inserting a double flare portion of a metal tube into the connection wall of the connection object, abutting the funnel-shaped inner peripheral surface against the abutting surface, and caulking the cylindrical connection wall to double flare The process consists of a step of connecting and fixing the metal tube and the connection object by bringing the funnel-shaped inner peripheral surface of the double flare part and the funnel-shaped abutment surface of the connection object into close contact with each other by caulking the part. This is a connection method between a pipe and its connection object.

本発明は上述の如く構成したものであり、接続対象物の接続壁をダブルフレア部の外周にカシメ固定した際に、ダブルフレア部の漏斗状の内周面を接続対象物の漏斗状の突当面に強くかつ均一な力で密着させる事で、面圧の高い密着が可能となり、信頼性の高い気密性や液密性を得る事ができる。また、この漏斗状の内周面と漏斗状の突当面との密着であるから、厳密な寸法合わせや工作精度を必要としなくても、変形や肉厚の偏り等を防止して、同芯度良く組み付けて、固定安定性の高い接続構造を得る事ができる。そして、この信頼性の高い気密性又は液密性と、固定安定性を有する接続構造を、円筒状の接続壁をダブルフレア部の外周にカシメ固定するだけの作業で行う事ができるとともに、金属管と接続対象物との接続に、ナットやシール部材等を使用する必要がなく、部品点数や組み付け工程を省く事ができ、接続作業を容易かつ効率的に行う事が可能となる。また、ナット等の締め付け部材の使用がない分、接続構造をコンパクトにする事ができるとともに、接続作業時に広い作業スペースを必要とせず、狭い設置場所であっても設置が可能で、しかも容易な接続が可能となり、レイアウトの自由度の高い製品を得る事ができる。   The present invention is configured as described above, and when the connection wall of the connection object is caulked and fixed to the outer periphery of the double flare part, the funnel-shaped inner peripheral surface of the double flare part is connected to the funnel-like protrusion of the connection object. By adhering to the surface with strong and uniform force, adhesion with high surface pressure is possible, and highly airtight and liquid-tight properties can be obtained. In addition, since the funnel-shaped inner peripheral surface and the funnel-shaped abutting surface are in close contact with each other, it is possible to prevent deformation, uneven thickness, etc. without requiring strict dimensional alignment or work accuracy. It can be assembled well and a connection structure with high fixation stability can be obtained. And this highly reliable airtight or liquid-tight connection structure with fixing stability can be performed by simply caulking and fixing the cylindrical connection wall to the outer periphery of the double flare part. It is not necessary to use a nut or a seal member for connecting the pipe and the connection object, so that the number of parts and the assembling process can be omitted, and the connection work can be performed easily and efficiently. In addition, the connection structure can be made compact by eliminating the use of nuts and other tightening members, and it does not require a large work space during connection work. Connection is possible, and a product with a high degree of freedom in layout can be obtained.

以下、本発明を自動車、各種の機械装置等に給油、給気等の供給路として使用される金属管に於いて実施した一例を図面に於て説明すれば、(１)は金属管で、二重巻鋼管を使用している。この金属管(１)の先端縁側を、内側に二重に折り曲げて、図２に示す如く、外方幅広の漏斗状のダブルフレア部(２)を形成している。このダブルフレア部(２)は、図２に示す漏斗状の内周面(３)の形成角度ｄを９０°で形成している。   Hereinafter, an example in which the present invention is implemented in a metal pipe used as a supply path for oil supply, air supply, etc. in automobiles, various mechanical devices, etc. will be described with reference to the drawings. (1) is a metal pipe, Double-rolled steel pipe is used. The leading edge side of the metal tube (1) is bent inwardly to form a funnel-shaped double flare portion (2) having an outward width as shown in FIG. In the double flare portion (2), the formation angle d of the funnel-shaped inner peripheral surface (3) shown in FIG.

一方、上記金属管(１)を接続する管継手等の接続対象物(５)は、内部に流体の流通路(８)を設けるとともに、この流通路(８)の開口先に、図２に示す如く、金属管(１)の接続時にダブルフレア部(２)の漏斗状の内周面(３)を当接する漏斗状の突当面(６)を突設している。更に、この突当面(６)の外周に、ダブルフレア部(２)の外周面(４)を被覆可能な円筒状の接続壁(７)を突出形成している。この接続壁(７)は、ダブルフレア部(２)の外周面(４)にカシメ固定されるものであるから、このカシメ固定を容易とするために、先端側を次第に薄肉に形成するとともに、このカシメ時に、前述の如く、ダブルフレア部(２)の外周面(４)全体を被覆可能な寸法で形成する。尚、接続壁(７)の基部側は、金属管(１)の強固な固定を可能なように、比較的厚肉に形成している。   On the other hand, the connection object (5) such as a pipe joint for connecting the metal pipe (1) is provided with a fluid flow passage (8) inside, and the opening of the flow passage (8) is shown in FIG. As shown, a funnel-shaped abutting surface (6) is provided so as to abut the funnel-shaped inner peripheral surface (3) of the double flare portion (2) when the metal tube (1) is connected. Furthermore, a cylindrical connection wall (7) capable of covering the outer peripheral surface (4) of the double flare portion (2) is formed on the outer periphery of the abutting surface (6). Since this connection wall (7) is caulked and fixed to the outer peripheral surface (4) of the double flare portion (2), in order to facilitate this caulking, the tip side is gradually formed thin, At the time of this caulking, as described above, the entire outer peripheral surface (4) of the double flare portion (2) is formed with a size that can be covered. The base side of the connection wall (7) is formed relatively thick so that the metal tube (1) can be firmly fixed.

上記金属管(１)を接続対象物(５)に接続固定するには、金属管(１)のダブルフレア部(２)を接続対象物(５)の接続壁(７)内に挿入し、ダブルフレア部(２)の漏斗状の内周面(３)を、漏斗状の突当面(６)に当接する。次に、チャック部材(図示せず)により接続対象物(５)及び金属管(１)を各々固定し、パンチ(図示せず)を管軸方向にスライドさせる事により接続壁(７)をカシメ加工する。この接続壁(７)によりダブルフレア部(２)をカシメ固定する事で、図１に示す如く、ダブルフレア部(２)の漏斗状の内周面(３)と接続対象物(５)の漏斗状の突当面(６)とを密着させて、金属管(１)と接続対象物(５)とを接続固定する事ができる。   In order to connect and fix the metal pipe (1) to the connection object (5), the double flare portion (2) of the metal pipe (1) is inserted into the connection wall (7) of the connection object (5), and The funnel-shaped inner peripheral surface (3) of the double flare portion (2) is brought into contact with the funnel-shaped abutting surface (6). Next, the connection object (5) and the metal pipe (1) are each fixed by a chuck member (not shown), and the connection wall (7) is caulked by sliding the punch (not shown) in the pipe axis direction. Process. By fixing the double flare portion (2) by caulking with the connection wall (7), as shown in FIG. 1, the funnel-shaped inner peripheral surface (3) of the double flare portion (2) and the connection object (5) The metal tube (1) and the connection object (5) can be connected and fixed by closely contacting the funnel-shaped abutting surface (6).

このカシメ固定により、金属管(１)の漏斗状の内周面(３)と、接続対象物(５)の漏斗状の突当面(６)とが、厳密な寸法合わせや位置合わせを行わなくても、高い面圧で同芯良く密着するものとなり、金属管(１)と接続対象物(５)との接続構造を、気密性、液密性の高いものとする事ができるとともに、強固で安定の良い接続が可能となる。従って、金属管(１)及び接続対象物(５)の流通路(８)内を燃料やガス等が流動する際の流動圧や自動車、機械装置の振動等の刺激を受けても、金属管(１)と接続対象物(５)との接続構造の気密性や液密性が損なわれる事がなく、漏れを良好に防止して、耐久性に優れる製品を得る事ができる。   By this caulking, the funnel-shaped inner peripheral surface (3) of the metal tube (1) and the funnel-shaped abutting surface (6) of the connection object (5) do not perform strict alignment and alignment. However, it will be in good concentric contact with high surface pressure, and the connection structure between the metal tube (1) and the connection object (5) can be made to be highly airtight and liquid-tight and strong. A stable connection is possible. Therefore, even if the metal pipe (1) and the flow path (8) of the connection object (5) are subjected to stimulation such as fluid pressure when fuel or gas flows or vibrations of automobiles or mechanical devices, the metal pipe The airtightness and liquid-tightness of the connection structure between (1) and the object to be connected (5) are not impaired, and a product with excellent durability can be obtained by preventing leakage well.

また、この気密性、液密性及び固定安定性の高い金属管(１)と接続対象物(５)との接続を、円筒状の接続壁(７)のカシメのみで行う事ができ、従来の如くナット等を使用する必要がないし、厳密な製作精度で行う必要がなく、容易に行う事ができる。また、接続構造が大径とならず、狭いスペースへの設置も可能となるとともに、接続作業に工具の回動するための広いスペースを確保する必要もなく、設置のレイアウトの自由度の高いものとなる。   Further, the metal pipe (1) having high airtightness, liquid tightness and fixing stability and the connection object (5) can be connected only by caulking of the cylindrical connection wall (7). Thus, it is not necessary to use a nut or the like, and it is not necessary to carry out with strict manufacturing accuracy, and it can be carried out easily. In addition, the connection structure does not have a large diameter, and installation in a narrow space is possible, and there is no need to secure a wide space for rotating the tool for connection work, and there is a high degree of freedom in installation layout. It becomes.

また、上記実施例では、二重巻鋼管を金属管(１)として使用しているが、一重巻鋼管、アルミ管、ステンレス鋼管、銅管等を使用した場合も、同様の接続方法と接続構造により、気密性、液密性、及び固定安定性に優れる接続が可能となる。   Moreover, in the said Example, although the double wound steel pipe is used as a metal pipe (1), also when using a single wound steel pipe, an aluminum pipe, a stainless steel pipe, a copper pipe etc., the same connection method and connection structure This makes it possible to connect with excellent air tightness, liquid tightness, and fixing stability.

また、上記実施例では、金属管(１)のダブルフレア部(２)の漏斗状の内周面(３)の形成角度を、９０°で形成しているが、１２０°で形成しても良く、ダブルフレア部(２)の管軸方向の形成長さを短くする事ができる。この９０°〜１２０°の範囲内で形成する事により、ダブルフレア部(２)を、突当面(６)に面圧高く密着させる事ができる。   Moreover, in the said Example, although the formation angle of the funnel-shaped inner peripheral surface (3) of the double flare part (2) of a metal pipe (1) is formed at 90 degrees, even if it forms at 120 degrees The formation length of the double flare portion (2) in the tube axis direction can be shortened. By forming within the range of 90 ° to 120 °, the double flare portion (2) can be brought into close contact with the abutting surface (6) with high surface pressure.

本発明の一実施例で、接続壁をカシメてダブルフレア部をカシメ固定する事により、金属管と接続対象物とを接続固定した状態の断面図。Sectional drawing of the state which connected and fixed the metal pipe and the connection target object by crimping a connection wall and crimping and fixing a double flare part in one Example of this invention. ダブルフレア部を設けた金属管と、円筒状の接続壁を設けた接続対象物との、接続前の状態を示す断面図。Sectional drawing which shows the state before the connection of the metal tube which provided the double flare part, and the connection target object which provided the cylindrical connection wall.

符号の説明Explanation of symbols

１ 金属管
２ ダブルフレア部
３ 内周面
４ 外周面
５ 接続対象物
６ 突当面
７ 接続壁 DESCRIPTION OF SYMBOLS 1 Metal pipe 2 Double flare part 3 Inner peripheral surface 4 Outer peripheral surface 5 Connection object 6 Abutting surface 7 Connection wall

Claims (2)

金属管の先端縁側を内側に二重に折り曲げて外方幅広の漏斗状のダブルフレア部を形成し、このダブルフレア部を、接続対象物に設けた円筒状の接続壁内に挿入するとともに、ダブルフレア部の漏斗状の内周面を接続対象物の漏斗状の突当面に当接し、ダブルルフレア部の外周面に接続壁をカシメてダブルフレア部をカシメ固定する事により、ダブルフレア部の漏斗状の内周面と接続対象物の漏斗状の突当面とを密着させた事を特徴とする金属管とその接続対象物との接続構造。   The tip end side of the metal tube is double-folded inward to form an outwardly wide funnel-shaped double flare portion, and this double flare portion is inserted into a cylindrical connection wall provided in the connection object, The double flare section is affixed by abutting the funnel-shaped inner peripheral surface of the double flare section with the funnel-shaped abutting surface of the connection object and caulking the connection wall to the outer peripheral surface of the double flare section and fixing the double flare section by caulking A connection structure between a metal tube and its connection object, characterized in that the funnel-shaped inner peripheral surface of the tube and the funnel-shaped abutment surface of the connection object are brought into close contact with each other. 金属管の先端縁側を、内側に二重に折り曲げて外方幅広の漏斗状のダブルフレア部を形成する工程と、この金属管を接続する接続対象物に、ダブルフレア部の漏斗状の内周面を当接する漏斗状の突当面を形成するとともに、この漏斗状の突当面の外周に、ダブルフレア部の外周面を被覆可能な接続壁を円筒状に突出形成する工程と、この接続対象物の接続壁内に金属管のダブルフレア部を挿入し、その漏斗状の内周面を突当面に当接する工程と、前記円筒状の接続壁をカシメてダブルフレア部をカシメ固定する事により、ダブルフレア部の漏斗状の内周面と接続対象物の漏斗状の突当面とを密着させて金属管と接続対象物とを接続固定する工程とから成る事を特徴とする金属管とその接続対象物との接続方法。   The tip edge side of the metal tube is folded twice inward to form an outwardly wide funnel-shaped double flare portion, and the connection object to which this metal tube is connected is connected to the funnel-shaped inner periphery of the double flare portion. Forming a funnel-shaped abutting surface that abuts the surface, and forming a connecting wall that can cover the outer peripheral surface of the double flare portion in a cylindrical shape on the outer periphery of the funnel-shaped abutting surface; By inserting the double flare portion of the metal tube into the connection wall of the metal tube, contacting the funnel-shaped inner peripheral surface to the abutting surface, and caulking the cylindrical connection wall to fix the double flare portion by caulking and fixing, The metal tube and its connection comprising a step of connecting and fixing the metal tube and the connection object by closely contacting the funnel-shaped inner peripheral surface of the double flare part and the funnel-shaped abutting surface of the connection object Connection method with the object.

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