JPS6222712Y2 - - Google Patents

Description

【考案の詳細な説明】 本考案は、熱可塑性合成樹脂製の管体を接続す
るための管継手に関し、特に熱可塑性合成樹脂製
の筒状体に電熱線が埋込まれて成る管継手の改良
に関する。[Detailed description of the invention] The present invention relates to a pipe joint for connecting pipe bodies made of thermoplastic synthetic resin, and particularly to a pipe joint in which a heating wire is embedded in a cylindrical body made of thermoplastic synthetic resin. Regarding improvements.

熱可塑性合成樹脂たとえばポリエチレン製の管
の配管において管体を接続するには、接続すべき
２つの管体の端部を突合わせておいてヒータで加
熱すれば、両者が一体的に熱溶着して接続され
る。この場合、両管体の端面間には溶着代が必要
であるが、たとえば都市ガスを輸送するために地
中に埋設・固定されて動かすことができない管体
では、適正な溶着代を取ることは困難である。そ
のため従来では、両管体の端部が挿入される円筒
状の継手本体と、その継手本体の内周面および管
体の端部外周面の間隙に両端からシール部材を挟
圧してシールするための押輪とを含む金属製の管
継手によつて接続している。この管継手によれば
両管体の端面間の距離の多少の変動は許容され
る。この管継手の継手本体は金属製であるので、
地中においては腐食し易い。 To connect pipes made of thermoplastic synthetic resin, such as polyethylene, the ends of the two pipes to be connected are butted together and heated with a heater, so that they are thermally welded together. connected. In this case, a welding allowance is required between the end faces of both pipes, but for example, for pipes that are buried and fixed underground to transport city gas and cannot be moved, it is necessary to take an appropriate welding allowance. It is difficult. For this reason, in the past, sealing was achieved by squeezing a sealing member from both ends into the gap between the cylindrical joint body into which the ends of both pipes are inserted, the inner peripheral surface of the joint body, and the outer peripheral surface of the ends of the pipe body. It is connected by a metal pipe joint containing a press ring. According to this pipe joint, some variation in the distance between the end faces of both pipe bodies is allowed. The fitting body of this pipe fitting is made of metal, so
It corrodes easily underground.

上述の技術的課題を解決する先行技術は、第５
図に示されている。この先行技術では、熱可塑性
合成樹脂たとえばポリエチレンから成る筒状体５
０に電熱線５１が埋込まれた管継手５２を用いて
いる。電熱線５１は、筒状体５０の全内周面近く
に、軸線方向に沿つて螺旋状にかつ電熱線５１の
外周の一部を筒状体の内周面から露出させて埋込
まれている。この筒状体の両端に、接続されるべ
きポリエチレン製の管体５３，５４の端部をそれ
ぞれ嵌入して、電熱線５１を電力付勢する。そう
すると、電熱線５１の発熱によつて筒状体５０の
内周面と管体５３，５４の外周面とが加熱され
る。筒状体５０を、その全外周にわたつて締付金
具で固定しておくと、筒状体５０は半径方向外方
への熱膨脹を抑えられる。そのため筒状体５０の
内周面と管体５３，５４の外周面とは相互に圧接
して一体的に熱溶着される。このとき電熱線５１
と筒状体５０との熱膨脹係数の相違によつて、筒
状体５０内で電熱線５１の外周に空間５９が生じ
ることが考えられる。そのため、その空間５９が
両管体５３，５４の端面間における筒状体５０の
内周面から筒状体５０の外方に連通して、気密性
が損なわれる恐れがある。また電熱線の熱膨脹係
数は比較的大きいため、電熱線５１は加熱されて
軟かくなつた筒状体５０内周面に半径方向外方に
向けて食込む。そのため両管体５３，５４の端面
間における筒状体５０の内周面に、管内に向けて
開放された環状の凹溝６０が生じることがある。
筒状体５０に曲げモーメント５７，５８などがか
かると、この凹溝６０に応力が集中してクラツク
が発生する恐れがある。 The prior art that solves the above technical problem is the fifth
As shown in the figure. In this prior art, a cylindrical body 5 made of a thermoplastic synthetic resin such as polyethylene is used.
A pipe joint 52 in which a heating wire 51 is embedded is used. The heating wire 51 is embedded near the entire inner peripheral surface of the cylindrical body 50 in a spiral shape along the axial direction, with a part of the outer periphery of the heating wire 51 being exposed from the inner peripheral surface of the cylindrical body. There is. The ends of polyethylene tubes 53 and 54 to be connected are respectively fitted into both ends of this cylindrical body, and the heating wire 51 is energized with electric power. Then, the inner circumferential surface of the cylindrical body 50 and the outer circumferential surfaces of the tube bodies 53 and 54 are heated by the heat generated by the heating wire 51. By fixing the cylindrical body 50 over its entire outer periphery with a fastening fitting, the cylindrical body 50 can be prevented from thermally expanding outward in the radial direction. Therefore, the inner circumferential surface of the cylindrical body 50 and the outer circumferential surfaces of the tube bodies 53 and 54 are pressed against each other and are integrally heat-welded. At this time, the heating wire 51
It is conceivable that a space 59 is created around the outer periphery of the heating wire 51 within the cylindrical body 50 due to the difference in coefficient of thermal expansion between the cylindrical body 50 and the cylindrical body 50 . Therefore, the space 59 communicates with the outside of the cylindrical body 50 from the inner circumferential surface of the cylindrical body 50 between the end faces of both the tubular bodies 53 and 54, and there is a possibility that airtightness may be impaired. Further, since the heating wire has a relatively large coefficient of thermal expansion, the heating wire 51 bites radially outward into the inner peripheral surface of the cylindrical body 50, which has become soft due to heating. Therefore, an annular groove 60 that is open toward the inside of the tube may be formed on the inner circumferential surface of the cylindrical body 50 between the end surfaces of both the tube bodies 53 and 54.
If a bending moment 57, 58 is applied to the cylindrical body 50, stress may be concentrated on the groove 60, causing a crack.

第５図示の先行技術の他の重要な問題は、曲げ
強度が小さいことである。螺旋状に埋め込まれて
いる電熱線５１は、筒状体５０の両最端部５０
ａ，５０ｂにおいて、全周にわたつて位置するこ
とができない。すなわち筒状体５０の両最端部５
０ａ，５０ｂにおいては、筒状体５０と管体５
３，５４との熱溶着が行なわれない部分５５，５
６が生じることになる。したがつて筒状体５０と
管体５３，５４との接続後に、管体５３，５４に
参照符５７，５８で示される曲げモーメントが作
用すると、その熱溶着されていない両最端部５０
ａ，５０ｂの前記非溶着部分５５，５６付近にお
いて応力集中現象が生じ、これによつてクラツク
が発生する恐れがある。このクラツクの発生は、
筒状体５０および管体５３，５４が、たとえばポ
リエチレンであつて界面活性剤に接触している
と、一層生じやすくなる。このようにして先行技
術では、筒状体５０の両最端部５０ａ，５０ｂに
おいて、管体５３，５４との熱溶着がされない部
分５５，５６が存在することによつて、曲げ強度
が劣つていた。 Another important problem with the prior art shown in Figure 5 is its low bending strength. The heating wire 51 embedded in a spiral shape is located at both extreme ends 50 of the cylindrical body 50.
a, 50b, cannot be located all around the circumference. That is, both extreme ends 5 of the cylindrical body 50
0a, 50b, the cylindrical body 50 and the tube body 5
3, 54 where the heat welding is not performed 55, 5
6 will occur. Therefore, when a bending moment indicated by reference numerals 57 and 58 is applied to the tubes 53 and 54 after the cylindrical body 50 and the tubes 53 and 54 are connected, both ends 50 which are not thermally welded
A stress concentration phenomenon occurs near the non-welded portions 55 and 56 of a and 50b, which may cause cracks. The occurrence of this crack is
If the cylindrical body 50 and the tube bodies 53, 54 are made of polyethylene and are in contact with a surfactant, this phenomenon is more likely to occur. In this way, in the prior art, the bending strength is poor due to the existence of the portions 55, 56 that are not thermally welded to the tube bodies 53, 54 at both extreme ends 50a, 50b of the tube body 50. was.

もつと詳しく述べると、第６図１で示されるよ
うに曲げモーメント５７が作用したとき、非溶着
部分５５の基端５０ａにおいて、応力集中現象に
より、矢符６０の方向に筒状体５０と管体５３と
の溶着部分に沿つてクラツクが伸展していく。 To be more specific, when a bending moment 57 is applied as shown in FIG. The crack extends along the welded portion with the body 53.

他の先行技術は、たとえば特公昭33−4429に開
示されている。この先行技術では、電熱線として
無端環状のリングが管軸方向に複数個隔置されて
熱可塑性合成樹脂製筒状体に埋込まれており、こ
のリングはその一直径線上で管軸方向に延びる一
対のリード線に溶接によつてそれぞれ固定され
る。リード線もまた筒状体に埋込まれる。このよ
うな先行技術では、電熱線がリングであり、リー
ド線に固定してあるので、その構成が比較的複雑
であり、生産性に劣る。 Other prior art is disclosed, for example, in Japanese Patent Publication No. 33-4429. In this prior art, a plurality of endless rings as heating wires are spaced apart in the tube axis direction and embedded in a thermoplastic synthetic resin cylindrical body. They are each fixed to a pair of extending lead wires by welding. Lead wires are also embedded in the tubular body. In such prior art, the heating wire is a ring and is fixed to the lead wire, so the structure is relatively complicated and productivity is poor.

したがつて本考案の目的は、熱可塑性合成樹脂
製の筒状体に電熱線が埋込まれて成る管継手の気
密性を向上させるとともに、曲げ強度を向上させ
ることである。 Therefore, an object of the present invention is to improve the airtightness and bending strength of a pipe joint in which a heating wire is embedded in a cylindrical body made of thermoplastic synthetic resin.

本考案は、熱可塑性合成樹脂製の筒状体６の内
にその筒状体６と同心の螺旋状に電熱線１０が埋
込まれており、両端に接続されるべき熱可塑性合
成樹脂製の管体１，２が管軸方向に間隔をあけて
嵌入され、前記電熱線１０を電力付勢して発熱さ
せ、前記筒状体６と前記管体１，２とを熱溶着す
る管継手において、前記電熱線１０は、管体１，
２が嵌入される筒状体の部分のみに設けられてお
り、この筒状体は電熱線１０が設けられている前
記部分よりも軸線方向両外方に延びている延長部
分を有し、これらの延長部分には電熱線１０が設
けられておらず、筒状体６の電熱線１０が埋込ま
れていない軸線方向外方に延長した部分の内径
を、電熱線１０が埋込まれている部分の内径より
大径とすることによつて、間隔１９が形成される
ことを特徴とする管継手である。 In the present invention, a heating wire 10 is embedded in a cylindrical body 6 made of thermoplastic synthetic resin in a spiral shape concentric with the cylindrical body 6, and a heating wire 10 made of thermoplastic synthetic resin is connected to both ends. In a pipe joint in which tube bodies 1 and 2 are fitted with a gap in the tube axis direction, the heating wire 10 is energized to generate heat, and the cylindrical body 6 and the tube bodies 1 and 2 are thermally welded. , the heating wire 10 has a tubular body 1,
2 is provided only in the part of the cylindrical body into which the heating wire 10 is fitted, and this cylindrical body has an extension part extending outward in the axial direction from the part in which the heating wire 10 is provided. The heating wire 10 is not provided in the extended portion of the cylindrical body 6, and the heating wire 10 is embedded in the inner diameter of the portion of the cylindrical body 6 extending outward in the axial direction where the heating wire 10 is not embedded. This pipe joint is characterized in that a gap 19 is formed by making the diameter larger than the inner diameter of the part.

第１図は本考案の一実施例の縦断面図であり、
第２図は第１図の−線から見た断面図であ
る。第１図は接続が行われる以前の状態を示す。
熱可塑性合成樹脂たとえばポリエチレンから成る
管体１，２は、たとえば都市ガスなどを輸送する
ために地中に埋設される。これらの管体１，２の
端部３，４は、本考案に従う管継手５によつて接
続される。管継手５の筒状体６は熱可塑性合成樹
脂たとえばポリエチレンから成る。筒状体６に
は、後述の両埋込み位置８，９の範囲内で、電熱
線１０，１１が埋込まれている。筒状体６の外周
には、たとえばヒンジ１２によつて半割状に開閉
自在の締付金具１３が取外し自在に嵌められる。
電熱線１０，１１には電源１４および電圧調整装
置１５が直列にそれぞれ接続される。 FIG. 1 is a longitudinal sectional view of an embodiment of the present invention,
FIG. 2 is a sectional view taken along the - line in FIG. 1. FIG. 1 shows the situation before a connection is made.
Pipe bodies 1 and 2 made of thermoplastic synthetic resin, such as polyethylene, are buried underground in order to transport, for example, city gas. The ends 3, 4 of these tubes 1, 2 are connected by a pipe joint 5 according to the invention. The cylindrical body 6 of the pipe joint 5 is made of thermoplastic synthetic resin, such as polyethylene. Heating wires 10 and 11 are embedded in the cylindrical body 6 within the range of both embedded positions 8 and 9, which will be described later. A fastening fitting 13 which can be opened and closed in half by means of a hinge 12, for example, is removably fitted onto the outer periphery of the cylindrical body 6.
A power source 14 and a voltage regulator 15 are connected in series to the heating wires 10 and 11, respectively.

第３図は管継手５の斜視図である。電熱線１
０，１１は、筒状体６の内周面７の両埋込み位置
８，９で、電熱線１０，１１の外周の一部を内周
面７から露出させて埋込まれる。この埋込み位置
８，９は、筒状体６両端から軸線方向に長さｌ１
だけ入込んだ中央位置の両端において、管体１，
２の端面間の長さｌ２を除いた長さｌ３をそれぞ
れ有する。電熱線１０は、折返し点１６を埋込み
位置８の第１図における左端部に位置させて、円
周方向に平行にかつ軸線方向に沿つて螺旋状に埋
込まれる。電熱線１０の引出し線１７，１８は筒
状体６と管体１の端部３との間隙１９から第１図
の右方に引出される。この間隙１９は、第１図に
明らかなように、筒状体６の電熱線１０が埋込ま
れていない軸線方向外方に延長した部分の内径
を、電熱線１０が埋込まれている部分の内径より
大径とすることによつて形成される。そのため管
１，２の外周面と、筒状体の電熱線１０が埋込ま
れている部分の内周面とをぴつたりと接触して熱
溶着することができ、気密性の向上を図ることが
できる。電熱線１１は、折返し点を埋込み位置９
の第１図における右端部に位置させて、円周方向
に平行にかつ軸線方向に沿つて螺旋状に埋込まれ
る。電熱線１１の引出し線２０，２１は、筒状体
６と管体２との間隙２２から第１図の左方に引出
される。引出し線１７，１８；２０，２１に電源
１４と電圧調整装置１５とを直列にそれぞれ接続
して、電力付勢する。そうすると筒状体６の内周
面７で、長さｌ３を有する埋込み位置８，９に埋
込まれている電熱線１０，１１がそれぞれ発熱す
る。その熱によつて、埋込み位置８，９におい
て、管体１，２の外周面と筒状体６の内周面７と
が加熱される。そのため管体１，２の端部３，４
は半径方向外方に向けて熱膨脹する。筒状体６の
外周には、締付金具１３が嵌められているので、
筒状体６の半径方向外方への熱膨脹は抑えられ
る。そのため管体１，２の外周面と筒状体６の内
周面７とは強固に圧接される。しかして管体１，
２と筒状体６とは、一体的に熱溶着される。 FIG. 3 is a perspective view of the pipe joint 5. heating wire 1
0 and 11 are embedded positions 8 and 9 on the inner circumferential surface 7 of the cylindrical body 6, and the heating wires 10 and 11 are embedded with part of their outer peripheries exposed from the inner circumferential surface 7. The embedded positions 8 and 9 have a length l1 in the axial direction from both ends of the cylindrical body 6.
At both ends of the central position where the tube body 1,
Each has a length l3 excluding the length l2 between the two end faces. The heating wire 10 is spirally embedded parallel to the circumferential direction and along the axial direction, with the turning point 16 located at the left end of the embedding position 8 in FIG. The lead wires 17 and 18 of the heating wire 10 are drawn out to the right in FIG. 1 from a gap 19 between the cylindrical body 6 and the end 3 of the tubular body 1. As is clear from FIG. 1, this gap 19 is defined by the inner diameter of the portion of the cylindrical body 6 extending outward in the axial direction where the heating wire 10 is not embedded, and the portion where the heating wire 10 is embedded. It is formed by making the diameter larger than the inner diameter of. Therefore, the outer peripheral surfaces of the tubes 1 and 2 and the inner peripheral surface of the part of the cylindrical body in which the heating wire 10 is embedded can be tightly contacted and thermally welded, thereby improving airtightness. Can be done. The heating wire 11 has its turning point embedded at position 9.
It is located at the right end in FIG. 1 and embedded in a spiral shape parallel to the circumferential direction and along the axial direction. The lead wires 20 and 21 of the heating wire 11 are drawn out from the gap 22 between the cylindrical body 6 and the tube body 2 to the left in FIG. A power source 14 and a voltage regulator 15 are connected in series to the lead wires 17, 18; 20, 21, respectively, to apply power. Then, on the inner peripheral surface 7 of the cylindrical body 6, the heating wires 10 and 11 embedded in the embedded positions 8 and 9 having a length l3 generate heat, respectively. The heat heats the outer circumferential surfaces of the tubular bodies 1 and 2 and the inner circumferential surface 7 of the cylindrical body 6 at the embedding positions 8 and 9. Therefore, the ends 3, 4 of the tubes 1, 2
thermally expands radially outward. Since the tightening fitting 13 is fitted on the outer periphery of the cylindrical body 6,
Thermal expansion of the cylindrical body 6 in the radial direction outward is suppressed. Therefore, the outer circumferential surfaces of the tubular bodies 1 and 2 and the inner circumferential surface 7 of the cylindrical body 6 are firmly pressed together. However, the tube body 1,
2 and the cylindrical body 6 are integrally heat welded.

筒状体６の軸線方向両端の電熱線１０，１１が
埋込まれていない部分は、ほとんど加熱されな
い。したがつて筒状体６の内周面７と管体１，２
の外周面との間隙１９，２２は、軸線方向に長さ
ｌ１をそれぞれ有したままであり、熱溶着されな
い。 The portions of the axially opposite ends of the cylindrical body 6 where the heating wires 10 and 11 are not embedded are hardly heated. Therefore, the inner peripheral surface 7 of the cylindrical body 6 and the tubes 1 and 2
The gaps 19 and 22 between the outer circumferential surface and the outer circumferential surface thereof each remain the length l1 in the axial direction, and are not thermally welded.

第４図は、管体１の端部３と筒状体６との熱溶
着部２３付近の拡大断面図である。接続操作が終
了して締付金具１３を取外した後、管体１の端部
３と筒状体６との熱溶着部２３に曲げ荷重がかか
つた場合を想定する。第４図の矢符２４で示す如
く、管体１に曲げモーメントが作用すると、仮想
線１ａで示す如く管体１が筒状体６の内周面７の
端部に支持されて、管体１にかかつている曲げ荷
重の一部は筒状体６によつて分担される。このこ
とを確実にするために、筒状体６の両端の電熱線
１０，１１が埋込まれていない部分の長さｌ１を
充分に大きくとつている。そのため管体１が筒状
体６の内周面７の端部に当接するまでの角変位量
αを可及的に小さくして、管体１を筒状体６によ
つて支持させる。それによつて熱溶着部２３に応
力が集中することが防がれる。 FIG. 4 is an enlarged cross-sectional view of the vicinity of the heat-welded portion 23 between the end portion 3 of the tubular body 1 and the cylindrical body 6. FIG. A case is assumed in which a bending load is applied to the heat-welded portion 23 between the end portion 3 of the tubular body 1 and the cylindrical body 6 after the connection operation is completed and the fastening fitting 13 is removed. When a bending moment is applied to the tubular body 1 as shown by the arrow 24 in FIG. A part of the bending load applied to 1 is shared by cylindrical body 6. In order to ensure this, the length l1 of the portion at both ends of the cylindrical body 6 where the heating wires 10, 11 are not embedded is set to be sufficiently large. Therefore, the angular displacement amount α until the tubular body 1 comes into contact with the end of the inner circumferential surface 7 of the tubular body 6 is made as small as possible, and the tubular body 1 is supported by the tubular body 6. This prevents stress from concentrating on the heat welded portion 23.

筒状体６の軸線方向両端の電熱線１０が埋込ま
れていない部分は、軸線方向外方に延長してあ
り、この両端延長部分の内周面７と管体１，２の
外周面との間には間隙１９が形成される。間隙１
９の半径方向の長さは参照符δで示されている。 The portions at both axial ends of the cylindrical body 6 in which the heating wires 10 are not embedded extend outward in the axial direction, and the inner circumferential surface 7 of these both end extended portions and the outer circumferential surfaces of the tubular bodies 1 and 2 A gap 19 is formed between them. Gap 1
The radial length of 9 is indicated by the reference δ.

したがつて第６図２で示されるように、管体１
に矢符８０で示される曲げモーメントが作用した
ときには管体１の外周面に筒状体６の軸線方向外
方端６２に当接する。したがつて管体１には筒状
体６との溶着位置からこの軸線方向外方端６２と
の間で角変位置αだけ曲がる。管体１に大きな曲
げモーメント８０が作用したときには、この管体
１は軸線方向外方端６２を支点として角変位置β
だけさらに曲がる。こうして管体１は二段階に角
変位置α，βだけ角変位することになり、管体１
に作用する応力が低減される。 Therefore, as shown in FIG.
When a bending moment indicated by an arrow 80 acts on the outer peripheral surface of the tubular body 1, the axially outer end 62 of the cylindrical body 6 comes into contact with the outer peripheral surface of the tubular body 1. Therefore, the tubular body 1 is bent by an angular displacement position α between the welded position with the cylindrical body 6 and this axially outer end 62. When a large bending moment 80 is applied to the tubular body 1, the tubular body 1 shifts to an angular position β with the axially outer end 62 as a fulcrum.
Only bend further. In this way, the tube body 1 is angularly displaced by the angular displacement positions α and β in two steps, and the tube body 1
The stress acting on is reduced.

これに対して第６図１で示された先行技術では
管体５３に曲げモーメント５７が作用したときに
は、筒状体５０の軸方向外方端６３を支点として
屈曲し、その角変位量は第６図２と同じ曲げモー
メントが作用したときには、角変位量は（α＋
β）となる。このようにして管体５３は単一の支
点６３の周りに大きく角変位することになる。し
たがつて基端５０ａにおける応力集中現象が大き
くなり、き裂が極めて生じ易い。 On the other hand, in the prior art shown in FIG. 6, when a bending moment 57 is applied to the tubular body 53, the tubular body 50 is bent about the axially outer end 63 of the tubular body 50 as a fulcrum, and the amount of angular displacement is 6 When the same bending moment as in Fig. 2 is applied, the amount of angular displacement is (α+
β). In this way, the tubular body 53 undergoes a large angular displacement around the single fulcrum 63. Therefore, the stress concentration phenomenon at the base end 50a increases, and cracks are extremely likely to occur.

本考案は、このような先行技術の問題を解決
し、応力集中現象の緩和が図られる。 The present invention solves the problems of the prior art and alleviates the stress concentration phenomenon.

管体２と筒状体６との熱溶着部においても、上
述と同様にその熱溶着部に応力が集中することが
防がれる。 Also in the heat welded portion between the tubular body 2 and the cylindrical body 6, stress is prevented from concentrating on the heat welded portion in the same way as described above.

本考案によれば、管体１，２端面間の距離ｌ２
の範囲内において、筒状体６には電熱線が埋込ま
れていない。したがつて管体１，２と筒状体６と
が熱溶着された時点で、電熱線１０，１１が管内
に露出されることはない。そのため熱膨脹係数の
差によつて、たとえ筒状体６内で電熱線１０，１
１の外周に空間が生じたとしても、その空間が管
内と筒状体６の外方とにわたつて連通することは
なく、気密性が優れている。 According to the present invention, the distance l2 between the end surfaces of the tubes 1 and 2
Within this range, no heating wire is embedded in the cylindrical body 6. Therefore, when the tube bodies 1, 2 and the cylindrical body 6 are thermally welded, the heating wires 10, 11 are not exposed inside the tube. Therefore, due to the difference in coefficient of thermal expansion, even if the heating wires 10 and 1
Even if a space is created around the outer periphery of the tube 1, the space does not communicate between the inside of the tube and the outside of the cylindrical body 6, and the airtightness is excellent.

また電熱線１０，１１が筒状体６の内周面７に
半径方向外方に向けて食込んでも、管体１，２の
端部３，４間における内周面７に管内に向けて開
放された環状の凹溝が生じることはない。そのた
め、曲げ荷重などによつて筒状体６の内周面７に
クラツクが発生する恐れはなく、曲げ強度が従来
のものより優れている。 Furthermore, even if the heating wires 10 and 11 bite into the inner circumferential surface 7 of the tubular body 6 radially outward, the heating wires 10 and 11 do not cut into the inner circumferential surface 7 between the ends 3 and 4 of the tubular bodies 1 and 2 toward the inside of the tube. No open annular grooves are formed. Therefore, there is no fear that cracks will occur on the inner circumferential surface 7 of the cylindrical body 6 due to bending loads, and the bending strength is superior to conventional ones.

第７図を参照して、本考案では、電熱線１０が
筒状体６内に、その筒状体６と同心の螺旋状に埋
込まれている。したがつて筒状体６と管体１との
融着強度の管軸方向の分布は、管軸を通る一平面
内で第７図の上方では、参照符７１で示されるよ
うに、また第７図の下方では参照符７２で示され
るように分布している。このようにして筒状体６
と管体１との融着強度が軸線方向に均一化される
ので、強度が増大される。 Referring to FIG. 7, in the present invention, a heating wire 10 is embedded in a cylindrical body 6 in a spiral shape concentric with the cylindrical body 6. Therefore, the distribution of the fusion strength between the cylindrical body 6 and the tube body 1 in the tube axis direction is as indicated by reference numeral 71 in the upper part of FIG. 7 within a plane passing through the tube axis. In the lower part of FIG. 7, the distribution is as indicated by reference numeral 72. In this way, the cylindrical body 6
Since the strength of the fusion bond between the tube body 1 and the tube body 1 is made uniform in the axial direction, the strength is increased.

本件考案者の実験結果を示す。前述の実施例に
おいて筒状体６に管体１，２が接続されており、
管体１がその管外径の５倍の曲率半径で湾曲する
ように曲げモーメント８０が作用し、その雰囲気
温度は50℃とし、管体１に供給されている内圧は
２Kg／cm²としたときにおいて、ガス漏れの発生は
見られず、クラツクの発生が生じないことが確認
された。これに対して第５図に示された先行技術
において同様な実験を行なつたところ、ガス漏れ
が発生した。こうして本考案によれば、応力集中
が抑制され、クラツクの発生が防がれることが確
認された。 The experimental results of the inventor of this case are shown below. In the above-mentioned embodiment, the tubular bodies 1 and 2 are connected to the cylindrical body 6,
A bending moment of 80 was applied so that the pipe body 1 was bent with a radius of curvature five times the outer diameter of the pipe, the ambient temperature was 50°C, and the internal pressure supplied to the pipe body 1 was ² kg/cm2. At times, no gas leakage was observed, and it was confirmed that no cracks occurred. On the other hand, when a similar experiment was conducted using the prior art shown in FIG. 5, gas leakage occurred. Thus, it was confirmed that the present invention suppresses stress concentration and prevents the occurrence of cracks.

上述の如く本考案によれば、管体が嵌入される
筒状体の部分すなわち筒状体と管体とが重なつて
いる部分にのみ電熱線が設けられており、管体の
端面間においては、筒状体には電熱線が埋込まれ
ない。すなわち第１図に示されるように、電熱線
１０，１１は、長さｌ３においてのみ設けられて
おり、残余の長さｌ１，ｌ２には設けられていな
いことが重要である。そのため筒状体と管体との
熱溶着後に筒状体内で電熱線の外周に生じ得る空
間が管内と連通せず、したがつて気密性が向上さ
れる。また熱溶着時に電熱線が筒状体内にめり込
んだ状態においても、管体の端面間では筒状体内
周面に凹溝が生じることはなく、したがつて応力
集中に起因する曲げ強度の低下が防がれる。 As described above, according to the present invention, the heating wire is provided only in the portion of the tubular body into which the tubular body is inserted, that is, the portion where the tubular bodies overlap, and the heating wire is provided between the end surfaces of the tubular bodies. No heating wire is embedded in the cylindrical body. That is, as shown in FIG. 1, it is important that the heating wires 10 and 11 are provided only in the length l3 and not in the remaining lengths l1 and l2. Therefore, after the cylindrical body and the tubular body are thermally welded, a space that may be created around the outer periphery of the heating wire within the cylindrical body does not communicate with the inside of the tube, thus improving airtightness. Furthermore, even if the heating wire sinks into the cylindrical body during thermal welding, no grooves will be formed on the circumferential surface of the cylindrical body between the end faces of the tube, and therefore the bending strength will not decrease due to stress concentration. Prevented.

また本考案によれば、熱可塑性合成樹脂製の筒
状体の電熱線が埋込まれていない両端を、軸線方
向外方に延長して形成したので、筒状体と管体と
の熱溶着部に曲げモーメントを受けたとき、応力
集中が発生することが防がれ、したがつて前述し
た従来の管継手に比べて曲げ強度が向上される。 Furthermore, according to the present invention, both ends of the thermoplastic synthetic resin cylindrical body in which the heating wires are not embedded are extended outward in the axial direction, so that the cylindrical body and the tubular body can be thermally welded. When a bending moment is applied to the pipe joint, stress concentration is prevented from occurring, and therefore the bending strength is improved compared to the conventional pipe fittings described above.

【図面の簡単な説明】[Brief description of the drawings]

第１図は本考案の一実施例の縦断面図、第２図
は第１図の−線視断面図、第３図は管継手５
の斜視図、第４図は管体１の端部３と筒状体６と
の熱溶着部２３付近の拡大断面図、第５図は先行
技術の縦断面図、第６図は先行技術と本考案の一
実施例との作用を説明するための断面図、第７図
は本考案の一実施例の溶着強度の分布を示す断面
図である。 １，２……管体、３，４……端部、５……管継
手、６……筒状体、７……筒状体６の内周面、
８，９……埋込み位置、１０，１１……電熱線、
１３……締付金具、１９，２２……筒状体６と管
体１，２との間隙、２３……熱溶着部、α，β…
…管体１の角変位量、δ……間隙１９の半径方向
長さ。 Fig. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, Fig. 2 is a cross-sectional view taken along the - line of Fig. 1, and Fig. 3 is a pipe joint 5.
FIG. 4 is an enlarged sectional view of the vicinity of the heat welded portion 23 between the end 3 of the tubular body 1 and the cylindrical body 6, FIG. 5 is a vertical sectional view of the prior art, and FIG. 6 is the prior art. FIG. 7 is a sectional view showing the distribution of welding strength in an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1, 2... Pipe body, 3, 4... End part, 5... Pipe joint, 6... Cylindrical body, 7... Inner peripheral surface of the cylindrical body 6,
8, 9...embedding position, 10,11...heating wire,
13...Tightening metal fitting, 19, 22...Gap between cylindrical body 6 and tube bodies 1, 2, 23...Heat welding part, α, β...
...Amount of angular displacement of tube body 1, δ...Radial length of gap 19.

Claims (1)

【実用新案登録請求の範囲】[Scope of utility model registration request] 熱可塑性合成樹脂製の筒状体６の内にその筒状
体６と同心の螺旋状に電熱線１０が埋込まれてお
り、両端に接続されるべき熱可塑性合成樹脂製の
管体１，２が管軸方向に間隔をあけて嵌入され、
前記電熱線１０を電力付勢して発熱させ、前記筒
状体６と前記管体１，２とを熱溶着する管継手に
おいて、前記電熱線１０は、管体１，２が嵌入さ
れる筒状体の部分のみに設けられており、この筒
状体は電熱線１０が設けられている前記部分より
も軸線方向両外方に延びている延長部分を有し、
これらの延長部分には電熱線１０が設けられてお
らず、筒状体６の電熱線１０が埋込まれていない
軸線方向外方に延長した部分の内径を、電熱線１
０が埋込まれている部分の内径より大径とするこ
とによつて、間隙１９が形成されることを特徴と
する管継手。 A heating wire 10 is embedded in a spiral shape concentric with the cylindrical body 6 in a cylindrical body 6 made of thermoplastic synthetic resin, and a cylindrical body 1 made of thermoplastic synthetic resin to be connected to both ends. 2 are inserted at intervals in the tube axis direction,
In the pipe joint in which the heating wire 10 is energized to generate heat to thermally weld the cylindrical body 6 and the tube bodies 1 and 2, the heating wire 10 is connected to a tube into which the tube bodies 1 and 2 are fitted. The cylindrical body is provided only in a portion of the cylindrical body, and this cylindrical body has an extension portion extending outward in the axial direction from the portion where the heating wire 10 is provided,
The heating wire 10 is not provided in these extended portions, and the inner diameter of the portion of the cylindrical body 6 extending outward in the axial direction in which the heating wire 10 is not embedded is defined as the heating wire 1
A pipe joint characterized in that a gap 19 is formed by making the diameter larger than the inner diameter of the part where the 0 is embedded.