JPH1034719A - Manufacture of electric fusion bonded joint - Google Patents
Manufacture of electric fusion bonded jointInfo
- Publication number
- JPH1034719A JPH1034719A JP19622296A JP19622296A JPH1034719A JP H1034719 A JPH1034719 A JP H1034719A JP 19622296 A JP19622296 A JP 19622296A JP 19622296 A JP19622296 A JP 19622296A JP H1034719 A JPH1034719 A JP H1034719A
- Authority
- JP
- Japan
- Prior art keywords
- member layer
- joint
- injection molding
- outer member
- joint body
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D23/00—Producing tubular articles
- B29D23/001—Pipes; Pipe joints
- B29D23/003—Pipe joints, e.g. straight joints
- B29D23/005—Pipe joints, e.g. straight joints provided with electrical wiring
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/57—Exerting after-pressure on the moulding material
- B29C45/572—Exerting after-pressure on the moulding material using movable mould wall or runner parts
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ガスや配水配管等
に用いられる熱可塑性樹脂製の管を電気融着接続するた
めの熱可塑性樹脂製管継手の内周面近傍に電熱線を巻回
埋設した電気融着式管継手を得る製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of winding a heating wire near an inner peripheral surface of a thermoplastic resin pipe joint for electrically welding and connecting a thermoplastic resin pipe used for gas or water distribution pipes. The present invention relates to a manufacturing method for obtaining a buried electrofusion type pipe joint.
【０００２】[0002]
【従来の技術】従来、電気融着式管継手は、図３に示す
ように、熱可塑性樹脂（ポリエチレン樹脂、ポリプロピ
レン樹脂、ポリ塩化ビニル樹脂、ポリブテン樹脂など）
からなる継手本体１の内周面に電熱線２を螺旋状に埋設
し、その両端をコネクターピン３，３に接続したもので
ある。また、図４に巻回埋設された電熱線２と内方部材
層４と外方部材層５の拡大断面図を示す。ところで、電
熱線２にコネクターピン３，３より通電し、これを加熱
することにより同じ熱可塑性樹脂製の管（図示せず）を
電気的に融着し接続するものである。この電気融着継手
は軽くて施工性に優れ、地震等にも強いことからガス用
埋設配管を中心に近年急速に普及しており、現在では呼
び径200mmの大口径配管にまで及んでいる。2. Description of the Related Art Conventionally, as shown in FIG. 3, an electrofusion type pipe joint is made of a thermoplastic resin (polyethylene resin, polypropylene resin, polyvinyl chloride resin, polybutene resin, etc.).
A heating wire 2 is helically buried in the inner peripheral surface of a joint body 1 made of, and both ends thereof are connected to connector pins 3, 3. FIG. 4 shows an enlarged cross-sectional view of the wound heating wire 2, the inner member layer 4, and the outer member layer 5. By the way, the heating wire 2 is energized from the connector pins 3 and 3 and is heated to electrically fuse and connect the same thermoplastic resin tube (not shown). These electrofusion joints are lightweight, have excellent workability, and are resistant to earthquakes and the like. Therefore, they have been rapidly spreading in recent years, mainly in buried pipes for gas, and now extend to large-diameter pipes having a nominal diameter of 200 mm.
【０００３】さて、この電気融着式管継手は、従来より
射出成形法で製造されており、例えば、インナー（図３
および図４の符号４）と呼ばれる内方部材層にコアを挿
通し、予め内方部材層の外面に成形されている螺旋溝に
電熱線２を巻回し、この内方部材層をコアと共に成形用
金型内にセットし、この上にアウター（図３および図４
の符号５）と呼ばれる外方部材層を射出成形して継手本
体１を得るという方法がとられてきた。[0003] This electrofusion type pipe joint has conventionally been manufactured by an injection molding method.
The core is inserted into an inner member layer called reference numeral 4) in FIG. 4, and the heating wire 2 is wound around a spiral groove formed in advance on the outer surface of the inner member layer, and the inner member layer is formed together with the core. Set in the mold for the outer case (see FIGS. 3 and 4).
The method of injection molding an outer member layer called reference numeral 5) to obtain the joint body 1 has been adopted.
【０００４】また、呼び口径およそ100mm以上の大口径
の電気融着式管継手を限られた設備で能率的に製造する
方法として、本願発明者らが特願平７−６３７８３号に
おいて提案した多層成形法がある。この多層成形法は、
本来、厚肉の継手本体を略均等厚さの樹脂成形層に分割
し、例えば外方部材層５を二つに分割し（図示せず）、
下層の外方部材層の上に上層の外方部材層を重ねて射出
成形して積層することによって継手本体を成形すること
も行われている。これによって、各成形段階での金型内
冷却固化時間が短縮でき、且つ同時成形が可能となるた
め生産性が大幅に向上する。As a method for efficiently manufacturing a large-diameter electro-fused pipe joint having a nominal diameter of about 100 mm or more with limited equipment, a multilayered structure proposed by the present inventors in Japanese Patent Application No. 7-63783 has been proposed. There is a molding method. This multilayer molding method
Originally, the thick joint body was divided into resin molding layers having a substantially uniform thickness, for example, the outer member layer 5 was divided into two (not shown),
In some cases, a joint main body is formed by stacking an upper outer member layer on a lower outer member layer by injection molding and laminating the outer member layer. Thereby, the cooling and solidifying time in the mold at each molding stage can be shortened, and simultaneous molding is possible, so that productivity is greatly improved.
【０００５】[0005]
【発明が解決しようとする課題】ところが、上記の電気
融着式管継手の製造方法では、図３、図４および図５に
示すごとく、内方部材層４の外周面に外方部材層５を形
成するために、コネクターピン３，３の上に位置するよ
うに成形金型７にスリーブ９，９をセットし、内方部材
層４の中に２個のコア８，８を左右から挿入し、内方部
材層４をこれらのコア８，８と共に成形金型７，７内に
セットして、溶融樹脂を射出成形機の射出筒（図示せ
ず）から矢印１０の方向にゲートを介して高圧で射出
し、成形金型７とスリーブ９と内方部材層４との間の空
間すなわちキャビティ部１１に溶融樹脂を充填すること
により外方部材層５を成形する。ここで、溶融樹脂の流
れ方向に対して凹凸のある部分の背後や近傍に気体の溜
まり部が生じ易くなる。特に段差の後ろや溝の後ろに気
体の溜まり部が生じる。気体の種類として、射出成形時
に溶融樹脂が巻き込む金型内の空気があり、射出した溶
融樹脂から発生するガスも含まれる。この溜まり部の気
体は、射出成形工程の溶融樹脂の圧力保持過程および冷
却固化過程の間に一ヶ所に集まって、ボイド６と呼ぶ空
洞部を形成してしまう。However, in the above-described method for manufacturing the electro-fusion type pipe joint, as shown in FIGS. 3, 4 and 5, the outer member layer 5 is formed on the outer peripheral surface of the inner member layer 4. The sleeves 9 and 9 are set in the molding die 7 so as to be located above the connector pins 3 and 3, and the two cores 8 and 8 are inserted into the inner member layer 4 from the left and right. Then, the inner member layer 4 is set together with the cores 8 and 8 in the molding dies 7 and 7, and the molten resin is supplied from an injection cylinder (not shown) of the injection molding machine through a gate in the direction of arrow 10. The outer member layer 5 is formed by filling the space between the molding die 7, the sleeve 9, and the inner member layer 4, that is, the cavity 11 with molten resin. Here, a gas reservoir tends to be formed behind or near a portion having irregularities in the flow direction of the molten resin. In particular, a gas reservoir is formed behind the step or the groove. As the type of gas, there is air in a mold into which a molten resin is involved during injection molding, and also includes gas generated from the injected molten resin. The gas in the pool collects in one place during the pressure holding process and the cooling and solidifying process of the molten resin in the injection molding process, and forms a cavity called a void 6.
【０００６】このボイドを解消する一つの手段として、
射出圧力とその圧力保持時間および金型内冷却固化時間
を増せば良いことが分かっている。しかし、この方法で
は成形歪みが益々ひどくなるし、また製造タクトが長く
なるという問題がある。As one means for eliminating the void,
It has been found that the injection pressure, the pressure holding time and the cooling and solidification time in the mold should be increased. However, in this method, there is a problem that the molding distortion is further increased and the manufacturing tact becomes longer.
【０００７】本発明は上記の問題を解決するもので、ボ
イドのような内部欠陥がなく成形歪みの少ない電気融着
式管継手の製造方法を提供することを目的とする。An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a method of manufacturing an electro-fused pipe joint which has no internal defects such as voids and has less molding distortion.
【０００８】[0008]
【課題を解決するための手段】本発明は、熱可塑性樹脂
を金型内のキャビティ部に射出成形して継手本体を得る
電気融着式管継手の製造方法において、前記継手本体に
内封される空気等のガスにより成形体内に生じるボイド
に隣接するキャビティ部の外部に加圧手段を設け、射出
成形後から冷却固化するまでに前記加圧手段を用いて前
記継手本体を部分的に加圧して前記ボイドを解消する過
程を含むものである。SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing an electro-fusion type pipe joint in which a thermoplastic resin is injection-molded into a cavity in a mold to obtain a joint body. A pressurizing means is provided outside the cavity adjacent to the void generated in the molded body by a gas such as air, and the joint body is partially pressurized by using the pressurizing means after injection molding until cooling and solidification. In order to eliminate the voids.
【０００９】[0009]
【発明の実施の形態】以下、本発明の実施の形態を実施
例にもとづき図面を参照して説明する。図１は一実施例
で加圧手段を設け外方部材層の射出成形直後の状態を示
す概念図であり、図２は加圧手段により継手本体を部分
的に加圧した状態を示す概念図である。図は、内方部材
層４の外周面に外方部材層５を射出成形する例を示し、
ここでは外方部材層４が１層である場合を示している
が、外方部材層を２層以上に分割したものであってもよ
い（図示せず）。また、本実施例では始めから一体成形
する継手本体を例示しているが、継手本体を二つに分割
してそれぞれ成形した後にそれらをバット融着により一
体化して継手本体を得る場合であっても同じである。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on embodiments with reference to the drawings. FIG. 1 is a conceptual view showing a state immediately after injection molding of an outer member layer provided with a pressing means in one embodiment, and FIG. 2 is a conceptual view showing a state in which the joint body is partially pressed by the pressing means. It is. The figure shows an example in which the outer member layer 5 is injection-molded on the outer peripheral surface of the inner member layer 4,
Here, the case where the outer member layer 4 is a single layer is shown, but the outer member layer 4 may be divided into two or more layers (not shown). Further, although the present embodiment illustrates a joint body integrally molded from the beginning, the joint body is divided into two parts, each of which is molded and then integrated by butt fusion to obtain a joint body. Is the same.
【００１０】外方部材層５を射出成形した後、図１に示
すように本実施例では、コネクター部１２の近傍で外方
部材層５の内部にボイド６が発生している。尚、ボイド
が発生する個所は、継手の形状や成形条件によって左右
され、例えばフランジ状の突起部の根元付近にも発生す
ることがある。このようにボイドの発生位置は定まった
ものではないが、概略の発生部位と大きさは経験的に特
定することができる。After the outer member layer 5 is injection-molded, voids 6 are formed in the outer member layer 5 near the connector 12 in this embodiment as shown in FIG. The location where the void occurs depends on the shape of the joint and the molding conditions, and may occur, for example, near the root of the flange-shaped protrusion. As described above, the position where the void is generated is not fixed, but the approximate location and size of the void can be empirically specified.
【００１１】発生部位が特定できるボイド６の上方で成
形金型７の外部に加圧手段１３、例えばエアシリンダ或
いは油圧シリンダを設置し、加圧手段１３の可動軸１３
ａの先端に加圧部材１３ｂを取り付け、加圧手段１３に
より生ずる力は、可動軸１３ａを介して加圧部材１３ｂ
により外方部材層５のボス部５ａに加わる。このことに
より、図２に示すようにボス部５ａの成形樹脂は、ボイ
ド部分６を押し潰すように空洞を埋めて、欠陥が解消さ
れる。また部分的に外方部材層を加圧することにより、
継手本体に与える歪みの影響を小さく抑えられる。A pressurizing means 13, for example, an air cylinder or a hydraulic cylinder, is installed outside the molding die 7 above the void 6 where the generation site can be specified, and the movable shaft 13
a pressure member 13b is attached to the end of the pressure member 13a, and the force generated by the pressure means 13 is applied to the pressure member 13b via the movable shaft 13a.
As a result, the boss portion 5a of the outer member layer 5 is joined. Thereby, as shown in FIG. 2, the molding resin of the boss portion 5a fills the cavity so as to crush the void portion 6, and the defect is eliminated. Also, by partially pressing the outer member layer,
The effect of distortion on the joint body can be reduced.
【００１２】以上、本発明の実施例としてボイド等の内
部欠陥のない継手本体を得る製造方法を図面により詳述
してきたが、具体的な構成はこの実施例に限られるもの
ではなく、本発明の要旨を逸脱しない範囲の設計変更等
があっても本発明に含まれる。As described above, the manufacturing method for obtaining a joint body free from internal defects such as voids has been described in detail with reference to the drawings as an embodiment of the present invention. However, the specific structure is not limited to this embodiment. Even if there is a design change or the like within a range not departing from the gist of the present invention, it is included in the present invention.
【００１３】[0013]
【発明の効果】以上の説明のごとく、本発明の電気融着
式管継手の製造方法にあっては、ボイド等の内部欠陥を
確実に無くし、圧力保持時間および金型内冷却固化時間
を短くして製造タクトを削減でき、延いては成形歪みの
少なくできる。As described above, in the method for manufacturing the electro-fusion type pipe joint of the present invention, internal defects such as voids are surely eliminated, and the pressure holding time and the cooling and solidifying time in the mold are shortened. As a result, the manufacturing tact can be reduced, and the molding distortion can be reduced.
【図１】 本発明の製造方法の一実施例で外方部材層の
射出成形直後の状態を示す概念図である。FIG. 1 is a conceptual diagram showing a state immediately after injection molding of an outer member layer in one embodiment of the production method of the present invention.
【図２】 本発明の製造方法の一実施例で加圧手段によ
り継手本体を部分的に加圧した状態を示す概念図であ
る。FIG. 2 is a conceptual diagram showing a state in which the joint body is partially pressurized by pressurizing means in one embodiment of the manufacturing method of the present invention.
【図３】 従来の電気融着式管継手の縦断面図である。FIG. 3 is a longitudinal sectional view of a conventional electrofusion type pipe joint.
【図４】 従来の電熱線と内方部材層および外方部材層
の拡大断面図である。FIG. 4 is an enlarged cross-sectional view of a conventional heating wire, an inner member layer, and an outer member layer.
【図５】 従来の製造方法の外方部材層の射出成形直後
の状態を表す概念図である。FIG. 5 is a conceptual diagram showing a state immediately after injection molding of an outer member layer in a conventional manufacturing method.
１…継手本体， ２…電熱線 ３…コネクターピン， ４…内方部材層 ５…外方部材層， ５ａ…ボス部 ６…ボイド， ７…樹脂成形金型 ８…コア， ９…スリーブ １０…溶融樹脂射出方向， １１…キャビティ部 １２…コネクター部， １３…加圧手段 １３ａ…可動軸， １３ｂ…加圧部材 DESCRIPTION OF SYMBOLS 1 ... Joint body, 2 ... Heating wire 3 ... Connector pin, 4 ... Inner member layer 5 ... Outer member layer, 5a ... Boss 6 ... Void, 7 ... Resin molding die 8 ... Core, 9 ... Sleeve 10 ... Injection direction of molten resin, 11: cavity portion 12: connector portion, 13: pressing means 13a: movable shaft, 13b: pressing member
Claims (1)
射出成形して継手本体を得る電気融着式管継手の製造方
法において、 前記継手本体に内封される空気等のガスにより成形体内
に生じるボイドに隣接するキャビティ部の外部に加圧手
段を設け、射出成形後から冷却固化するまでに前記加圧
手段を用いて前記継手本体を部分的に加圧して前記ボイ
ドを解消する過程を含むことを特徴とする電気融着式管
継手の製造方法。1. A method of manufacturing an electro-fusion type pipe joint for obtaining a joint body by injection molding a thermoplastic resin into a cavity in a mold, wherein a gas such as air enclosed in the joint body is used to form a molded body. A step of providing a pressurizing means outside the cavity portion adjacent to the void generated in the step, partially pressurizing the joint body using the pressurizing means after injection molding until cooling and solidifying, and eliminating the void. A method of manufacturing an electrofusion type pipe joint, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19622296A JPH1034719A (en) | 1996-07-25 | 1996-07-25 | Manufacture of electric fusion bonded joint |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19622296A JPH1034719A (en) | 1996-07-25 | 1996-07-25 | Manufacture of electric fusion bonded joint |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH1034719A true JPH1034719A (en) | 1998-02-10 |
Family
ID=16354239
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19622296A Pending JPH1034719A (en) | 1996-07-25 | 1996-07-25 | Manufacture of electric fusion bonded joint |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH1034719A (en) |
-
1996
- 1996-07-25 JP JP19622296A patent/JPH1034719A/en active Pending
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