JP4028698B2

JP4028698B2 - Molding method of resin hollow molded product, molded product and its mold

Info

Publication number: JP4028698B2
Application number: JP2001180889A
Authority: JP
Inventors: 幸久熊谷; 広和勝地
Original assignee: Polyplastics Co Ltd
Current assignee: Polyplastics Co Ltd
Priority date: 2001-06-14
Filing date: 2001-06-14
Publication date: 2007-12-26
Anticipated expiration: 2021-06-14
Also published as: JP2002370250A

Description

【０００１】
【発明の属する技術分野】
本発明は、２つ以上に分割した１次成形品を突き合わせて、突き合わせ面、接合フランジおよび接合溝とを形成し、該接合溝に樹脂を充填して、各１次成形品を接合一体化させて得られる中空成形品、成形方法、それに使用する成形用金型に関するものであり、得られた成形品の接合強度が向上する。
【０００２】
【従来の技術】
中空体等を成形する成形技術として、半割の１次成形品どうしを所定の形状に突き合わせて、突き合わせ面と接合溝とを形成し、該接合溝に樹脂を充填して一体となった成形品を得る成形方法として、特開昭62-87315号公報に記載されたダイスライドインジェクション法（以下ＤＳＩ法）、特開平4-91914号公報に記載されたダイロータリーインジェクション法（以下ＤＲＩ法）、その他インサート成形法で得られた半割の１次成形品を使用する方法等が知られている。
特にＤＳＩ法、ＤＲＩ法は溶着強度に優れ、生産性にも優れた成形方法として知られている。
【０００３】
中空成形品の一般的な構造の縦断面図を図１に示す。１、１’は半割状の１次成形品の各分割部分、２、２’は各分割部分の突き合わせ部分、５は各突き合わせ部分を突き合わせて形成された突き合わせ面、８、８’は各分割部分の接合フラシジ部分、９は接合フランジ部分を突き合わせて形成された接合フランジ、３、３’は各分割部分の接合フランジ内に設けられた接合溝部分、６は各接合溝部分から形成された接合溝、および４は成形品の中空部を示す。２０は接合樹脂部であり、接合溝６に２次樹脂（２次成形用樹脂または２次接合用樹脂ともいう）が充填されて形成され、各分割部分１、１’を接合一体化させる。
接合溝６は、移動金型側の天面１０’、固定金型側の底面１０、縦壁面１１、及び必要に応じて設けられる金型合わせ面側の面１２からなる。
図２に、突き合わせ面、接合フランジ、接合溝、接合樹脂部、及び接合溝と接合樹脂部の接合部の詳細を示す。接合部は、１次成形品の移動金型側の天面１０’、固定金型側の底面１０、縦壁面１１と２次成形で射出充填されて形成される接合樹脂部２０との接触面からなる。
７は突き合わせ面の溝側部分、７’は突き合わせ面の中空側部分を示す。
【０００４】
図３はＤＳＩ法による１次成形品の一般的な成形方法を示す図である。２１は固定金型、２１’は移動金型であり、１次成形品の各分割部分１、１’が成形される。
図４は、図３に続いて、型開きされ、駆動装置２３により移動金型をスライドさせて、２次成形用に移動させた状態を示す図である。
図５では、図４に続いて、型閉じされ、各分割部分１、１’を突き合わせ、突き合わせ面５と接合溝６が形成されて、所定の製品前駆体２６が形成される。更に、製品前駆体２６の接合溝６に２次樹脂が充填され、接合樹脂部２０が形成され、製品前駆体２６が接合一体化され、成形品（製品）２７が得られる。
【０００５】
接合溝６内に２次樹脂が充填される時、各分割部分１、１’の溝部分どうしは接合樹脂部２０と溶着されるが、突き合わせ部分２、２’どうしの間には実質的に樹脂は入らず、突き合わせ面５は溶着しない。また、接合樹脂部２０と接合溝６との接合部については、２次成形用樹脂ゲート近傍内では樹脂温度も高く、圧力も高いため１次成形品と２次樹脂の溶着接合強度は高いが、樹脂の流動末端側では樹脂温度、射出圧力の低下により接合溶着強度が低下してくる。
図１０に示すように、接合強度を向上させるための一般的な対策として、１次成形品の接合溝底面１０及び接合溝天面１０’に溶着山を設置するが、溶着山の設置範囲の１次成形品表面が全て２次成形樹脂の熱により溶融し、融着している状態にはなり難い。このように一般的な溶着山を設けた場合、２次成形後の成形品の接合範囲を詳細に観察してみると、図１１に示す溶着山の凸部分３８（破線指示部分）では１次成形品の表面が２次成形時に再溶融し、１次成形品と２次樹脂が良好に接合していることが確認されたが、隣接する溶着山２８どうしの間に構成される谷部分３６及び１次成形品接合溝の突き合わせ面側縦壁部分１１及びこの縦壁部分１１と縦壁部分１１側の溶着山２８との間に構成されるエッジ状接合溝３７では接合が不充分で、簡単に接合界面で剥離することが確認された。特に縦壁部１１及びエッジ状接合溝３７の接合溶着不良があった場合、一体化された管状中空成形体に内側から圧力を加えた場合、溶着していない突き当て部端面部、即ち、突き合わせ面の溝側部分７に高い応力が発生し、縦壁部で僅かに接合溶着している部分が簡単に破壊し、その破壊によって生ずるクラックが接合溶着している溶着山の凸部分３８にも伝播し、管状体は低い内圧で簡単に破損しやすい。
水道関連商品、給湯器関連商品の管状体の中空体部品においては、非常に高い気密性、耐圧性能、長期耐圧信頼性が要求されるものが多く、従来の技術のみでは要求性能を満たすことが困難であった。
【０００６】
図７にパイプ状製品の斜視図を示す。パイプ１’の端部にパイプ２４が設けられる。円筒パイプは、従って、半割体１と、パイプ２４が設けられた半割体１’とが突き合わされて得られる。半割体１及び１’の外周部には、長さ方向に、フランジ９が一体的に設けられ、接合溝６を形成する。この接合溝６に２次射出工程で２次成形用スプルー、ランナー、ゲート（これらは図示せず。）を経由して溶融樹脂を射出充填し、接合樹脂部２０により、半割体１及び１’を接合一体化させる。
図８は、図７のパイプ状製品の本体パイプ部端末開口部を、本体パイプと同一材料の平板２５を熱板溶着法にて溶着させて塞いだものを、金型パーティング面と直角で本体パイプの軸方向に切断した時の状態を表す断面図である。２０は２次接合用樹脂を示し接合溝６内に形成される。この図８に示すような形態に本体パイプ部端末開口部を塞ぎ、パイプ２４の先端をネジ加工したものを、接合性能確認のための耐圧試験に用いた。
【０００７】
【発明が解決しようとする課題】
本発明の目的は、ダイスライドインジェクション法、またはダイロータリーインジェクション法により得られた中空成形品の接合溝と接合樹脂部との接合部の接合強度を高めることである。
【０００８】
【課題を解決するための手段】
本発明者は、接合溝６を構成する１次成形品表面と２次樹脂２０との接合界面の溶着状態の詳細な観察と、１次成形品の接合溝６の底面１０及び天面１０'に各種寸法形状の溶着山を設け、その時の詳細な接合界面観察及び耐圧試験を種々検討した結果、１次成形品接合溝６と接合樹脂部２０の接合強度が向上することを見い出し、本発明を完成するに至った。
【０００９】
すなわち本発明の第１は、１次成形用金型内で２つ以上に分割して成形され、突き合わせ部分（２）、接合フランジ部分（８）、接合フランジ部分（８）の内側に設けられた接合溝部分（３）を有する１次成形品の各分割部分（１）を、２次成形用金型内で突き合わせて、各突き合わせ部分（２）、接合フランジ部分（８）、接合溝部分（３）から、それぞれ突き合わせ面（５）、接合フランジ（９）、接合溝（６）を形成させて中空部を有する製品前駆体（２６）を得、該製品前駆体（２６）の接合溝（６）に２次樹脂を充填して接合樹脂部（２０）を形成させ、該製品前駆体（２６）を接合させて成形品（２７）を得るための１次成形用金型において、
接合溝（６）の底面部分（１０）及び天面部分（１０’）と突き合わせ面側縦壁部分（１１）によって構成される接合溝コーナー（３０）にＲ０．５ｍｍ以上のＲづけまたはＣ０．５ｍｍ以上のＣ面（カット面）づけを施した１次成形用金型を提供する。
本発明の第２は、接合溝（６）の底面部分（１０）及び天面部分（１０’）に溶着山（２８）が設けられた本発明の第１記載の１次成形用金型を提供する。
本発明の第３は、縦壁部分（１１）に最近接の溶着山（２８）の縦壁部分（１１）側に面した側面と、底面部分（１０）又は天面部分（１０’）とのコーナー（３１）の縦壁部分（１１）との間隔が１〜４ｍｍである本発明の第２記載の１次成形用金型を提供する。
本発明の第４は、隣接する溶着山（２８）どうしのコーナー間隔（３３）が０．２〜３ｍｍである本発明の第２又は３に記載の１次成形用金型を提供する。
本発明の第５は、溶着山（２８）の両側面と底面部分（１０）又は天面部分（１０’）とのコーナー（２９）及び（３１）にＲ０．３ｍｍ以上のＲづけが施された本発明の第２〜４のいずれかに記載の１次成形用金型を提供する。
本発明の第６は、本発明の第１〜５のいずれかに記載の１次成形用金型内で２つ以上に分割して成形された１次成形品の各分割部分（１）を突き合わせて、製品前駆体（３０）を得、該製品前駆体（３０）の接合溝（６）に樹脂を充填して、接合樹脂部（２０）を形成させる２次成形用金型を提供する。
本発明の第７は、１次成形用金型をスライド又は回転させて得られる本発明の第６に記載の２次成形用金型を提供する。
本発明の第８は、本発明の第１〜５のいずれかに記載の１次成形用金型で１次成形品を成形し、１次成形品の接合溝（６）に２次樹脂を射出充填して接合一体化させる成形方法を提供する。
本発明の第９は、ダイスライドインジェクション法、またはダイロータリーインジェクション法を用い、中空体成形を行う本発明の第８に記載の成形方法を提供する。
本発明の第１０は、本発明の第８又は９に記載の成形方法により得られた成形品を提供する。
【００１０】
【発明の実施の形態】
ＤＳＩ法により１次成形品の管状半割体を２次成形で接合一体化成形した管状体の耐圧試験を行った場合、その破壊は１次成形品接合溝と２次成形樹脂の溶着不良部が起点となっていて、その溶着不良は接合溝の鋭角な凹側角部やエッジ状凹状コーナー部や溶着山の谷部分に発生しやすいことが、本発明者による検討により確認された。
この高い応力発生部近傍の接合溶着強度を向上させないことには、耐圧性能の十分な向上は達成できない。２次成形時の接合部中空部側の縦壁部まで、充分に１次成形品と２次成形樹脂を溶着させる技術の確立が本問題の解決につながることに気付いた。
【００１１】
本発明に使用する１次成形品は、１次成形用金型内で、２つ以上に分割して１次成形される。１次成形品の分割数には制限はなく、３分割、４分割などの多分割が可能であるが、通常２分割である。１次成形品を成形する方法としてはＤＳＩ法、ＤＲＩ法のように２次成形用金型と兼用の金型で射出成形したり、予め用意した部品と複合成形するインサート成形法等が挙げられるが、これらに限定されるものではなく、各分割部分を別々の金型で成形して、それらを組み合わせて使用することもできる。
【００１２】
図９に、本発明の一例として、下半割体と上半割体を使用してＤＳＩ法で得られた中空成形体の突き合わせ面、接合溝、接合樹脂部の関係を示す。
突き合わせ面の形状には特に制限はなく、例えば突き合わせ部分２と２’を印籠形状にして、互いはまり合って、突き合わせ面５を形成するようにしてもよい。
【００１３】
接合溝を構成する天面１０’、底面１０は、平面で構成することも出来るが、表面に凹凸、例えば溶着山（ラビリンス）２８を設けたり、シボ加工することもできる。また、溶着山２８の基本形状は、必ずしも一例として示した図１２の３９に示すような二等辺三角形に限定されるものではなく、三角形の頂部をカットした台形形状、または三角形の頂部にＲづけしたような形状、更にそれらの斜辺は不等長であってもよい。
【００１４】
溶着山２８の底辺３２の幅は、成形品の大きさにもよるが、例えば０．５〜５ｍｍの範囲で設定され、好ましくは０．５〜１．５ｍｍの範囲に設定される。また、溶着山２８の高さ３４は、例えば０．３〜５ｍｍの範囲で設定されるが、好ましくは０．５〜１．５ｍｍの範囲に設定される。
【００１５】
従来は、図１０に示すように、接合溝６の縦壁部分１１のコーナー３０や、縦壁部分１１とこれに最近接の溶着山２８の底面のコーナー３１や、溶着山２８の斜辺と隣接する溶着山２８’の斜辺及び底面部１０で構成されるコーナー２９のコーナーにはＲづけされていない又はＲ０．３ｍｍ未満の極く小さなＲづけしか施されていなかった。
本発明では、図９に示すように、縦壁部分１１のコーナー部３０に０．５ｍｍ以上のＲづけまたはＣ面（カット面）づけを行うが、１．０ｍｍ以上が好ましい。図９では、部分円弧状のＲづけ３０’が例示されているが、Ｃ面づけは、部分円弧状が弦状になったものであり、弦の長さが０．５ｍｍ以上、好ましくは１．０ｍｍ以上である。
縦壁部分１１と、縦壁部分１１に最近接の溶着山２８のコーナー３１との間隔（コーナー３１から縦壁部分１１の延長線に下ろした垂直距離をいう。）は、１〜４ｍｍ、好ましくは１〜２ｍｍである。これにより、２次樹脂による接合効率が高くなる。
溶着山２８どうしのコーナー間隔３３（図９において溶着山２８と２８’のコーナーの底面における距離をいう。）は０．２〜３ｍｍ、０．４〜１ｍｍが好ましい。
また、溶着山のコーナーはＲづけ又はＣ面づけをした構造にすることもできる。
【００１６】
その他、本発明の成形金型及び成形方法の一例を図１〜図６を参考にして追加する。
図１では２次成形で接合一体化された一般的な成形品の断面図を示しているが、本発明での接合部は図９に示した形状のものを一例として示す。なお、成形品の端部にはフランジ等が設けられたり、成形品の途中には他の管等が設けられたりしてもよい。
図３〜図５は金型の製品キャビティ部のみの断面を示しているが、実際には図示されていない冷却回路、エジェクター機構、スプルー、ランナー、ゲート等が設置されている。
成形工程では、図３に示すように、金型キャビティに１次成形による合成樹脂成形材料を射出充填し、保圧・冷却工程後、型開きする。この時、１次成形品の分割部分（半割体）１’は移動型に残し、分割部分（半割体）１は固定型に残した状態となっている。
【００１７】
次に、図４に示すように図３に示す状態から型開きし、更に油圧シリンダー２３により移動金型２１’をスライドさせ、分割部分１’は移動型に残した状態で、分割部分１と１’を所定の製品前駆体２６の状態になるように型閉され突き合わされる。図５に示すように型閉が完了すると、突き合わせ面５と接合溝６が形成される。
次にこの接合溝６に２次樹脂が充填され、接合樹脂部２０が形成される。突き合わせ面５には２次成形の樹脂が注入されないため、溶着していない。接合溝６を構成する接合溝の底面１０、天面１０’、縦壁面１１のそれぞれの１次成形品表面を２次成形で射出充填させる溶融樹脂の熱により溶融させ、１次成形品樹脂材料と２次成形樹脂が融着される。
金型は、保圧・冷却工程後、型開きされ、製品である成形品がエジェクターピンにより突き出され成形が完了する。
【００１８】
本発明で使用できる成形用樹脂材料としては、中空射出成形が可能な樹脂であれば、制限はない。樹脂材料としては、合成樹脂でも天然に由来する樹脂でも、結晶性でも、非晶性でもよい。具体的には、合成樹脂としては、ポリエチレン、ポリプロピレン、ポリ４−メチルペンテン−１等のポリオレフィン；塩化ビニル系樹脂；ポリスチレン、ＡＢＳ等のスチレン系樹脂；ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリシクロヘキシレンテレフタレート、ポリエチレンナフタレート、ポリブチレンナフタレート等の芳香族ポリエステル；シュウ酸、吉草酸等の脂肪族ジカルボン酸類、エチレングリコール、プロパンジオール、プロピレングリコール、ブタンジオール、ブチレングリコール、ヘキサンジオール等のジオール類、及び／又は乳酸、カプロラクトン等からなる脂肪族ポリエステル；液晶性ポリエステル；ポリカーボネート；ポリアリレート；６−ナイロン、６，６−ナイロン、４，６−ナイロン、６，１２−ナイロンなどのポリアミド；ポリアセタール；ポリウレタン；フッ素樹脂；ポリフェニレンオキシド；ポリアリーレンサルファイド；ポリスルホン；ポリエーテルスルホン；ポリケトン；ポリエーテルケトン；ポリイミド；ポリエーテルイミド；ポリベンゾイミダゾール；シリコーン系樹脂；これらのアロイ等が挙げられる。
天然に由来する樹脂としては、微生物の産生するポリヒドロキシ酪酸のような脂肪族ポリエステル等が挙げられる。
樹脂には、各種の添加剤、離型剤、滑剤、充填材、強化剤等を必要により配合することができる。強化剤としては、ガラス繊維、炭素繊維、チタン酸カリウィスカ、酸化亜鉛ウィスカ、ボロン繊維などが挙げられる。また、各種安定剤、離型剤、滑剤等を添加することもできる。
【００１９】
【実施例】
以下、実施例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。
【００２０】
本発明による実施例及び従来形状の比較例の成形は、日本製鋼所製の２射出シリンダーを有するＤＳＩ用射出成形機Ｊ３５０Ｅ−Ｐ−ＭＦを使用し、表１に示す成形条件で成形を行った。
この実験に用いた成形用材料は、ポリプラスチックス株式会社製ＰＰＳ樹脂であるフォートロン１１３０Ｔ６を１次成形及び２次成形に用いた。また、表１に示す成形条件により成形を行った。
従来形状であるパイプ状ＤＳＩ成形品は、図７及び断面図８に示す基本形状で、パイプ部分の基本肉厚は３ｍｍ、内径φ１４ｍｍ、二次樹脂流路幅は５ｍｍのものを用いた。
【００２１】
［比較例１］
従来の技術による図１０の接合部構造を有する成形品を使用して、図１３に示すような状態で耐圧信頼性試験を行なった。溶着山の底辺３２は０．８ｍｍ、高さ３４は０．５ｍｍで、それぞれの溶着山は連続（即ち、コーナー間隔３３は０ｍｍ）して設けられ、接合溝コーナー３０及び溶着山のコーナー２９、３１にはＲづけをせず（Ｒ＝０）、接合溝縦壁部１１と最近接の溶着山との間隔３５は０．２ｍｍのものを用いた。２５は１次樹脂（＝２次樹脂）と同一の材料で別途成形された厚み４ｍｍの平板で、パイプ部端面に熱板溶着で溶着一体化されている。更にパイプ先端２４にはＰＴ（ピッチ）１／４”（インチ）のねじが加工してある。耐圧性能試験として中空体内部を水で置換し、ニップル４２を接続して固定する。ニップル４２に加圧ポンプ４３を接続し、テストポンプから成形品内部に加える水圧を、平均約１ＭＰａ／ｓｅｃで昇圧し、破壊した時の圧力を測定した。
【００２２】
［実施例１］
実施例１では、接合断面を図９に示すように変更し、パイプ部分の基本肉厚は３ｍｍで従来形状と同一とし、溶着山の底辺３２は０．８ｍｍ、高さ３４は０．５ｍｍで、それぞれの溶着山どうしのコーナー間隔３３は０．４ｍｍで、溶着山のコーナー２９、３１にはＲ＝０．３ｍｍ、接合溝コーナー３０はＲ＝１．０ｍｍ、接合溝縦壁部１１と最近接の溶着山との間隔３５は１．３ｍｍのものを用いた。
【００２３】
得られた成形品で、比較例と同様に耐圧信頼性試験を行ない、破壊した時の圧力を測定した。比較例及び本実施例共にｎ＝３で試験を行い、その結果を表２に示す。
【００２４】
【表１】

【００２５】
【表２】

【００２６】
比較例１の平均破壊圧力は５．３ＭＰａであったが、実施例１では、平均７．５ＭＰａと大幅な向上が認められた。また、比較例１の破壊面は図１４において太線で示すように、７を起点として、接合樹脂界面部分４４のような形状の破断面となり、その破断面は界面剥離に近い状態で破壊していた。
それに対し、実施例１では、図１５において太線で示すように、７を起点として、接合樹脂部６の中央部界面部分４５のような形状の破断面となり、その破断面は母材破壊であり、接合界面の剥離による欠陥の影響は見られなかった。
【００２７】
【発明の効果】
本発明により、耐圧性能と信頼性の向上にとって非常に重要となる１次成形品接合面と２次樹脂との接合不良が減少し、融着強度が改善できるようになる。更に、本発明による改善は非常に簡単な金型加工により実施でき、成形性にも悪影響を与えないため、コスト面でも有利なものとなっている。
【図面の簡単な説明】
【図１】中空成形品の一般的な構造の縦断面図である。
【図２】図１の接合部の詳細を示す図である。
【図３】ＤＳＩ法による１次成形品の一般的な成形方法を示す図である。
【図４】図３に続いて、型開きし、ダイスライドさせた状態を示す図である。
【図５】図４に続いて、型閉し、２次成形用金型を形成した状態を示す図である。
【図６】接合溝と、それに２次成形用樹脂を射出充填させるためのスプルー、ランナー、ゲートを示す図である。
【図７】一般的なパイプ状製品の斜視図である。
【図８】図７に示すパイプ状製品の開口部を平板で溶着し塞いだ状態のものを、金型パーティング面と直角でパイプ軸方向に切断した断面図である。
【図９】本発明の方法により成形した接合溝の１次成形品表面部の一例を示す断面図である。
【図１０】従来の方法により成形した接合溝の１次成形品表面部の一例を示す断面図である。
【図１１】図１０に示す１次成形品接合溝部に２次樹脂を射出充填した後の融着接合状態の一例を示す断面図である。
【図１２】接合溝の１次成形品表面部に設ける各種形状の溶着山の一例を示す断面図である。
【図１３】耐圧試験装置の図である。
【図１４】比較例１の耐圧試験後の破断面を示す接合部断面図である。
【図１５】実施例１の耐圧試験後の破断面を示す接合部断面図である。
【符号の説明】
１（１次成形品の）分割部分
１’（１次成形品の）分割部分
２突き合わせ部分
２’突き合わせ部分
３（１次成形品の）接合溝部分
３’（１次成形品の）接合溝部分
４中空部
５突き合わせ面
６（１次成形品の接合溝部分どうしを組み合わせて構成された）接合溝
７突き合わせ面５の溝側部分
７’突き合わせ面５の中空側部分
８接合フランジ部分
８’接合フランジ部分
９（接合フランジ部分どうしを組み合わせて構成された）接合フランジ
１０（１次成形品の）接合溝底面部分
１０’（１次成形品の）接合溝天面部分
１１接合溝の突き合わせ面側縦壁部分
１２接合溝のパーティング面側縦壁部分
１７２次成形用２次スプルー・ゲート
１８２次成形用ランナー
１９２次成形用ゲート
２０２次成形で接合溝に射出充填された接合樹脂部分
２１固定金型
２１’移動金型
２２金型のパーティング面
２３油圧シリンダー駆動装置
２４パイプ
２５閉塞用平板
２６製品前駆体
２７成形品
２８溶着山
２８’溶着山
２９（溶着山の）コーナー
３０（接合溝の縦壁部分１１の）接合溝コーナー
３０’（接合溝コーナー３０に設けられた）Ｒづけ
３１（縦壁部分１１に最近接の溶着山の縦壁部分１１側の）コーナー
３２（溶着山の）底辺長さ
３３（溶着山の）コーナー間隔
３４（溶着山の）高さ
３５縦壁部分１１に最近接の溶着山のコーナーと縦壁部分１１との間隔
３６１次成形品と２次成形樹脂の接合融着面で、１次成形品と２次成形樹脂が融着していない１次成形品の溶着山の谷に相当する部分
３７１次成形品接合溝の突き合わせ面側縦壁部分１１の１次成形品と２次成形樹脂の接合融着面で、その１次成形品と２次成形樹脂が融着していない部分
３８１次成形品と２次成形樹脂の接合融着面で、１次成形品の表面が２次成形樹脂の熱により再溶融し融着している部分
３９溶着山の頂点が鋭角形状である１次成形品の接合溝表面に設ける溶着山の基本形状
４０溶着山の頂点が平面形状である１次成形品の接合溝表面に設ける溶着山の基本形状
４１溶着山の頂点がＲ形状である１次成形品の接合溝表面に設ける溶着山の基本形状
４２ニップル
４３加圧ポンプ
４４比較例１の耐圧試験後の破断面
４５実施例１の耐圧試験後の破断面[0001]
BACKGROUND OF THE INVENTION
In the present invention, a primary molded product divided into two or more is abutted to form a butted surface, a joining flange, and a joining groove, and the joining groove is filled with a resin so that each primary molded product is joined and integrated. The present invention relates to a hollow molded product, a molding method, and a molding die used therefor, and the bonding strength of the obtained molded product is improved.
[0002]
[Prior art]
As a molding technology for molding hollow bodies, etc., the halved primary molded products are butted together into a predetermined shape, a butted surface and a joining groove are formed, and the joining groove is filled with a resin and integrated. As a molding method for obtaining a product, a die slide injection method (hereinafter referred to as DSI method) described in JP-A-62-87315, a die rotary injection method (hereinafter referred to as DRI method) described in JP-A-4-91914, In addition, a method of using a halved primary molded product obtained by the insert molding method is known.
In particular, the DSI method and the DRI method are known as molding methods having excellent welding strength and excellent productivity.
[0003]
A longitudinal sectional view of a general structure of a hollow molded article is shown in FIG. 1 and 1 'are each divided part of the half-shaped primary molded product, 2 and 2' are the abutting parts of each divided part, 5 is the abutting surface formed by abutting each abutting part, and 8 and 8 'are each The joining flange portion of the divided portion, 9 is a joining flange formed by abutting the joining flange portions, 3, 3 ′ are joining groove portions provided in the joining flange of each divided portion, and 6 is formed from each joining groove portion. The

joint grooves

4 and 4 indicate hollow portions of the molded product. Reference numeral 20 denotes a bonding resin portion, which is formed by filling the bonding groove 6 with a secondary resin (also referred to as a secondary molding resin or a secondary bonding resin), and unites the divided

portions

1 and 1 ′.
The joining groove 6 includes a top surface 10 'on the moving mold side, a bottom surface 10 on the fixed mold side, a vertical wall surface 11, and a surface 12 on the mold mating surface side provided as necessary.
FIG. 2 shows details of the abutting surface, the joining flange, the joining groove, the joining resin part, and the joining part between the joining groove and the joining resin part. The joint portion is a contact surface between the top surface 10 'on the moving mold side of the primary molded product, the bottom surface 10 on the fixed mold side, the vertical wall surface 11, and the joint resin portion 20 formed by injection filling in the secondary molding. Consists of.
Reference numeral 7 denotes a groove side portion of the abutting surface, and 7 ′ denotes a hollow side portion of the abutting surface.
[0004]
FIG. 3 is a diagram showing a general molding method of a primary molded product by the DSI method. 21 is a fixed mold, 21 'is a moving mold, and each divided part 1, 1' of the primary molded product is molded.
FIG. 4 is a diagram illustrating a state in which the mold is opened and the movable mold is slid by the driving device 23 and moved for secondary molding following FIG. 3.
In FIG. 5, following FIG. 4, the mold is closed, each divided

portion

1, 1 ′ is abutted, the abutting surface 5 and the joining groove 6 are formed, and a predetermined product precursor 26 is formed. Further, the secondary resin is filled in the joining groove 6 of the product precursor 26, the joining resin portion 20 is formed, the product precursor 26 is joined and integrated, and a molded product (product) 27 is obtained.
[0005]
When the secondary resin is filled in the joining groove 6, the groove parts of the respective divided parts 1, 1 'are welded to the joining resin part 20, but substantially between the butted parts 2, 2'. The resin does not enter and the butt surface 5 is not welded. In addition, the bonding portion between the bonding resin portion 20 and the bonding groove 6 has a high resin bonding temperature in the vicinity of the resin gate for secondary molding, and the pressure is high, so that the welded bonding strength between the primary molded product and the secondary resin is high. On the flow end side of the resin, the bonding weld strength decreases due to a decrease in the resin temperature and injection pressure.
As shown in FIG. 10, as a general measure for improving the bonding strength, welding peaks are installed on the bonding groove bottom surface 10 and the bonding groove top surface 10 'of the primary molded product. The surface of the primary molded product is all melted by the heat of the secondary molding resin, and is unlikely to be in a fused state. When a general welding ridge is provided in this way, when the joining range of the molded product after the secondary molding is observed in detail, the convex portion 38 (broken line indicating portion) of the welding hill shown in FIG. Although it was confirmed that the surface of the molded product was remelted during the secondary molding and the primary molded product and the secondary resin were satisfactorily joined, the valley portion 36 formed between the adjacent weld peaks 28 was confirmed. And the butted surface side vertical wall portion 11 of the primary molded product joint groove and the edge-shaped joint groove 37 formed between the vertical wall portion 11 and the welding ridge 28 on the vertical wall portion 11 side are insufficiently joined, It was confirmed that peeling easily occurred at the bonding interface. In particular, when there is poor welding of the vertical wall portion 11 and the edge-shaped joining groove 37, when pressure is applied to the integrated tubular hollow molded body from the inside, the abutting portion end surface portion that is not welded, that is, the butting High stress is generated in the groove-side portion 7 of the surface, the portion where welding is slightly welded in the vertical wall portion is easily broken, and the crack caused by the breakage is also formed on the convex portion 38 of the welding mountain where welding is welded. Propagating and the tubular body is easily damaged at low internal pressure.
Many of the hollow body parts of tubular bodies for water supply-related products and water heater-related products are required to have very high airtightness, pressure resistance, and long-term pressure reliability. It was difficult.
[0006]
FIG. 7 shows a perspective view of the pipe-like product. A pipe 24 is provided at the end of the pipe 1 ′. Accordingly, the cylindrical pipe is obtained by abutting the half body 1 and the half body 1 'provided with the pipe 24. A flange 9 is integrally provided on the outer peripheral portions of the

halves

1 and 1 ′ in the length direction to form a joining groove 6. In the secondary injection step, the joining groove 6 is filled with molten resin through a secondary molding sprue, runner, and gate (these are not shown), and the joining resin portion 20 divides the

halves

1 and 1. Integrate '.
FIG. 8 shows a case where the main pipe end opening of the pipe-shaped product of FIG. 7 is closed by welding a flat plate 25 made of the same material as that of the main pipe by a hot plate welding method at a right angle to the mold parting surface. It is sectional drawing showing the state when cut | disconnecting to the axial direction of a main body pipe. Reference numeral 20 denotes a secondary bonding resin, which is formed in the bonding groove 6. The main pipe end opening was closed in the form as shown in FIG. 8, and the tip of the pipe 24 was threaded, and used in a pressure test for confirming the joining performance.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to increase the bonding strength of the bonding portion between the bonding groove and the bonding resin portion of the hollow molded product obtained by the die slide injection method or the die rotary injection method.
[0008]
[Means for Solving the Problems]
The present inventor has made a detailed observation of the welded state of the bonding interface between the surface of the primary molded product constituting the bonding groove 6 and the secondary resin 20, and the bottom surface 10 and the top surface 10 'of the bonding groove 6 of the primary molded product. As a result of various welds having various dimensions and shapes, and various examinations of detailed bonding interface observation and pressure resistance test at that time, it was found that the bonding strength between the primary molded product bonding groove 6 and the bonding resin portion 20 is improved. It came to complete.
[0009]
That is, the first of the present invention is divided into two or more parts in the primary molding die, and is provided inside the butting part (2), the joining flange part (8), and the joining flange part (8). Each divided portion (1) of the primary molded product having the joined groove portion (3) is butted in the secondary molding die, and each butted portion (2), the joined flange portion (8), and the joined groove portion. From (3), a butting surface (5), a joining flange (9), and a joining groove (6) are formed to obtain a product precursor (26) having a hollow portion, and the joining groove of the product precursor (26) is obtained. In a primary molding die for filling a secondary resin into (6) to form a bonded resin portion (20) and bonding the product precursor (26) to obtain a molded product (27),
In the joining groove corner (30) constituted by the bottom surface portion (10) and the top surface portion (10 ') of the joining groove (6) and the abutting surface side vertical wall portion (11), an R rating of R0.5 mm or more or C0. Provided is a primary molding die having a C surface (cut surface) of 5 mm or more.
A second aspect of the present invention is the primary molding die according to the first aspect of the present invention, wherein a welding ridge (28) is provided on the bottom surface portion (10) and the top surface portion (10 ') of the joining groove (6). provide.
According to a third aspect of the present invention, a side surface facing the vertical wall portion (11) side of the weld pile (28) closest to the vertical wall portion (11), a bottom surface portion (10), or a top surface portion (10 ′) The metal mold | die for primary shaping | molding of the 2nd aspect of this invention whose space | interval with the vertical wall part (11) of the corner (31) of this invention is 1-4 mm is provided.
4th of this invention provides the metal mold | die for primary molding as described in 2nd or 3 of this invention whose corner space | interval (33) of adjacent weld piles (28) is 0.2-3 mm.
In the fifth aspect of the present invention, the corners (29) and (31) between the both side surfaces and the bottom surface portion (10) or the top surface portion (10 ′) of the weld pile (28) are provided with a radius of R 0.3 mm or more. A primary molding die according to any one of the second to fourth aspects of the present invention is provided.
According to a sixth aspect of the present invention, each divided portion (1) of the primary molded product formed by being divided into two or more in the primary molding die according to any one of the first to fifth aspects of the present invention. There is provided a secondary molding die for obtaining a product precursor (30) and filling a bonding groove (6) of the product precursor (30) with a resin to form a bonded resin portion (20). .
A seventh aspect of the present invention provides the secondary molding die according to the sixth aspect of the present invention, which is obtained by sliding or rotating the primary molding die.
According to an eighth aspect of the present invention, a primary molded product is molded with the primary molding die according to any one of the first to fifth aspects of the present invention, and a secondary resin is applied to the joining groove (6) of the primary molded product. A molding method for injection filling and joining and integrating is provided.
A ninth aspect of the present invention provides the molding method according to the eighth aspect of the present invention, in which hollow body molding is performed using a die slide injection method or a die rotary injection method.
A tenth aspect of the present invention provides a molded product obtained by the molding method according to the eighth or ninth aspect of the present invention.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
When a pressure resistance test is performed on a tubular body in which a tubular half of a primary molded product is joined and integrally molded by secondary molding by the DSI method, the failure is caused by a weld failure portion between the primary molded product joining groove and the secondary molded resin. It has been confirmed by the present inventors that the welding failure is likely to occur at sharp concave corners, edge-shaped concave corners, and valleys of weld peaks of the joining groove.
If the bonding weld strength in the vicinity of the high stress generating portion is not improved, sufficient improvement in pressure resistance performance cannot be achieved. It has been found that the establishment of a technique for sufficiently welding the primary molded product and the secondary molded resin to the vertical wall portion on the side of the joint hollow portion at the time of secondary molding leads to the solution of this problem.
[0011]
The primary molded product used in the present invention is primary molded by being divided into two or more in a primary molding die. There is no limitation on the number of divisions of the primary molded product, and multi-division such as 3-division and 4-division is possible, but it is usually 2-division. Examples of a method for forming a primary molded product include injection molding using a mold that is also used as a secondary molding die, such as the DSI method and DRI method, or an insert molding method in which composite molding is performed with a part prepared in advance. However, the present invention is not limited to these, and each divided portion may be molded with a separate mold and used in combination.
[0012]
As an example of the present invention, FIG. 9 shows the relationship between the butted surface, the joining groove, and the joining resin portion of a hollow molded article obtained by the DSI method using the lower half and the upper half.
The shape of the abutting surface is not particularly limited. For example, the abutting

portions

2 and 2 ′ may be formed as a stamped shape, and may be fitted together to form the abutting surface 5.
[0013]
The top surface 10 'and the bottom surface 10 constituting the joining groove can be formed as a flat surface, but the surface can be provided with unevenness, for example, a welded mountain (labyrinth) 28, or can be subjected to embossing. Further, the basic shape of the welding ridge 28 is not necessarily limited to the isosceles triangle as shown in 39 of FIG. 12 shown as an example, but a trapezoidal shape obtained by cutting the top of the triangle, or R on the top of the triangle. Such shapes, and their hypotenuses, may be of unequal length.
[0014]
Although the width | variety of the base 32 of the welding peak 28 is based also on the magnitude | size of a molded article, it sets in the range of 0.5-5 mm, for example, Preferably it sets in the range of 0.5-1.5 mm. Moreover, although the height 34 of the welding peak 28 is set in the range of 0.3-5 mm, for example, Preferably it is set in the range of 0.5-1.5 mm.
[0015]
Conventionally, as shown in FIG. 10, the corner 30 of the vertical wall portion 11 of the joining groove 6, the corner 31 of the bottom surface of the vertical wall portion 11 and the welding peak 28 closest thereto, and the oblique side of the welding mountain 28 are adjacent. The corner of the corner 29 constituted by the hypotenuse and the bottom surface portion 10 of the welding ridge 28 'is not rounded, or only a very small rounding of less than R0.3 mm is given.
In the present invention, as shown in FIG. 9, the corner portion 30 of the vertical wall portion 11 is subjected to R or C surface (cut surface) of 0.5 mm or more, preferably 1.0 mm or more. In FIG. 9, a partial arc-shaped R-shaped 30 ′ is illustrated, but the C surface is a chord-shaped partial arc, and the length of the string is 0.5 mm or more, preferably 1 0.0 mm or more.
The interval between the vertical wall portion 11 and the corner 31 of the welding peak 28 closest to the vertical wall portion 11 (referring to the vertical distance from the corner 31 to the extended line of the vertical wall portion 11) is 1 to 4 mm, preferably Is 1 to 2 mm. Thereby, the joining efficiency by secondary resin becomes high.
The corner interval 33 between the welding peaks 28 (referring to the distance between the bottom surfaces of the corners of the welding peaks 28 and 28 'in FIG. 9) is preferably 0.2 to 3 mm and 0.4 to 1 mm.
Further, the corners of the welded mountain can be made to have a structure with R or C surface.
[0016]
In addition, an example of the molding die and molding method of the present invention will be added with reference to FIGS.
Although FIG. 1 shows a cross-sectional view of a general molded product joined and integrated by secondary molding, the joined portion in the present invention is shown as an example having the shape shown in FIG. In addition, a flange etc. may be provided in the edge part of a molded product, and another pipe | tube etc. may be provided in the middle of a molded product.
3 to 5 show a cross section of only the product cavity of the mold, but a cooling circuit, an ejector mechanism, a sprue, a runner, a gate, etc., which are not actually shown, are installed.
In the molding process, as shown in FIG. 3, the mold cavity is filled with a synthetic resin molding material by primary molding, and the mold is opened after the pressure holding / cooling process. At this time, the divided part (half part) 1 ′ of the primary molded product is left in the movable mold, and the divided part (half part) 1 is left in the fixed mold.
[0017]
Next, as shown in FIG. 4, the mold is opened from the state shown in FIG. 3, and the movable mold 21 ′ is slid by the hydraulic cylinder 23. 1 ′ is closed and butted so as to be in a predetermined product precursor 26 state. When the mold closing is completed as shown in FIG. 5, the butt surface 5 and the joining groove 6 are formed.
Next, the bonding groove 6 is filled with the secondary resin, and the bonding resin portion 20 is formed. Since the secondary molding resin is not injected into the butt surface 5, it is not welded. The primary molded product resin material is obtained by melting the surfaces of the primary molded products of the bottom 10, the top surface 10 ′, and the vertical wall surface 11 of the joint groove 6 by heat of a molten resin that is injected and filled by secondary molding. The secondary molding resin is fused.
After the pressure holding / cooling step, the mold is opened, and the molded product is ejected by the ejector pin to complete the molding.
[0018]
The resin material for molding that can be used in the present invention is not limited as long as it is a resin that can be hollow injection molded. The resin material may be a synthetic resin or a naturally derived resin, crystalline or amorphous. Specifically, synthetic resins include polyolefins such as polyethylene, polypropylene and poly-4-methylpentene-1; vinyl chloride resins; styrene resins such as polystyrene and ABS; polyethylene terephthalate, polybutylene terephthalate, polycyclohexylene terephthalate. , Aromatic polyesters such as polyethylene naphthalate and polybutylene naphthalate; aliphatic dicarboxylic acids such as oxalic acid and valeric acid; diols such as ethylene glycol, propanediol, propylene glycol, butanediol, butylene glycol, and hexanediol; and / Or aliphatic polyester composed of lactic acid, caprolactone, etc .; liquid crystalline polyester; polycarbonate; polyarylate; 6-nylon, 6,6-nylon, 4,6-nylon, 6 Polyamide, such as 12-nylon; Polyacetal; Polyurethane; Fluororesin; Polyphenylene oxide; Polyarylene sulfide; Polysulfone; Polyethersulfone; Polyketone; Polyetherketone; Polyimide; Polyetherimide; Polybenzimidazole; Etc.
Examples of naturally occurring resins include aliphatic polyesters such as polyhydroxybutyric acid produced by microorganisms.
Various additives, release agents, lubricants, fillers, reinforcing agents and the like can be blended with the resin as necessary. Examples of the reinforcing agent include glass fiber, carbon fiber, potassium titanate whisker, zinc oxide whisker, and boron fiber. Various stabilizers, mold release agents, lubricants, and the like can also be added.
[0019]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
[0020]
For the molding of the examples according to the present invention and the comparative example of the conventional shape, molding was performed under the molding conditions shown in Table 1 using a DSI injection molding machine J350E-P-MF having two injection cylinders manufactured by Nippon Steel. .
As a molding material used in this experiment, Fortron 1130T6, which is a PPS resin manufactured by Polyplastics Co., Ltd., was used for primary molding and secondary molding. Moreover, it shape | molded on the molding conditions shown in Table 1.
A pipe-shaped DSI molded product having a conventional shape has a basic shape shown in FIG. 7 and a sectional view, and a pipe portion having a basic thickness of 3 mm, an inner diameter φ of 14 mm, and a secondary resin flow path width of 5 mm was used.
[0021]
[Comparative Example 1]
Using a molded article having the joint structure shown in FIG. 10 according to the prior art, a pressure resistance reliability test was performed in the state shown in FIG. The base 32 of the weld pile is 0.8 mm, the height 34 is 0.5 mm, and each weld pile is provided continuously (that is, the corner interval 33 is 0 mm). 31 was not provided with a radius (R = 0), and a gap 35 between the joining groove vertical wall portion 11 and the closest welding peak was 0.2 mm. Reference numeral 25 denotes a flat plate having a thickness of 4 mm separately formed of the same material as the primary resin (= secondary resin), and is integrally welded to the end surface of the pipe portion by hot plate welding. Further, a PT (pitch) 1/4 "(inch) screw is machined on the pipe tip 24. As a pressure resistance test, the inside of the hollow body is replaced with water, and a nipple 42 is connected and fixed. The pressurizing pump 43 was connected, the water pressure applied from the test pump to the inside of the molded product was increased at an average of about 1 MPa / sec, and the pressure at the time of failure was measured.
[0022]
[Example 1]
In Example 1, the joining cross section is changed as shown in FIG. 9, the basic thickness of the pipe portion is 3 mm, which is the same as the conventional shape, the base 32 of the weld pile is 0.8 mm, and the height 34 is 0.5 mm. The corner interval 33 between the welded mountains is 0.4 mm, the

corners

29 and 31 of the welded mountains are R = 0.3 mm, the joint groove corner 30 is R = 1.0 mm, and the joint groove vertical wall portion 11 is the latest. The distance 35 between the weld deposits was 1.3 mm.
[0023]
The obtained molded product was subjected to a pressure resistance reliability test in the same manner as in the comparative example, and the pressure at the time of failure was measured. Both the comparative example and the present example were tested at n = 3, and the results are shown in Table 2.
[0024]
[Table 1]

[0025]
[Table 2]

[0026]
The average breaking pressure of Comparative Example 1 was 5.3 MPa, but in Example 1, a significant improvement of 7.5 MPa was observed on average. Further, as shown by a thick line in FIG. 14, the fracture surface of Comparative Example 1 is a fracture surface having a shape like the bonding resin interface portion 44 starting from 7, and the fracture surface is broken in a state close to interface peeling. It was.
On the other hand, in Example 1, as shown by a thick line in FIG. 15, a fracture surface having a shape like the center interface portion 45 of the bonding resin portion 6 starts from 7 and the fracture surface is a base material fracture. There was no effect of defects due to peeling of the bonding interface.
[0027]
【The invention's effect】
According to the present invention, the bonding failure between the primary molded product bonding surface and the secondary resin, which is very important for improving the pressure resistance and reliability, can be reduced, and the fusion strength can be improved. Furthermore, the improvement according to the present invention can be carried out by a very simple mold processing and does not adversely affect the moldability, which is advantageous in terms of cost.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a general structure of a hollow molded article.
FIG. 2 is a diagram showing details of a joint portion in FIG. 1;
FIG. 3 is a diagram showing a general molding method of a primary molded product by a DSI method.
4 is a diagram showing a state where the mold is opened and the die is slid following FIG. 3. FIG.
FIG. 5 is a view showing a state in which the mold is closed and a secondary molding die is formed following FIG. 4;
FIG. 6 is a view showing a joining groove and sprues, runners, and gates for injecting and filling a secondary molding resin thereto.
FIG. 7 is a perspective view of a general pipe-shaped product.
8 is a cross-sectional view of the pipe-shaped product shown in FIG. 7 in which the opening is welded and closed with a flat plate and cut in the pipe axis direction at right angles to the mold parting surface. FIG.
FIG. 9 is a cross-sectional view showing an example of a surface portion of a primary molded product of a joining groove formed by the method of the present invention.
FIG. 10 is a cross-sectional view showing an example of a surface portion of a primary molded product of a joining groove formed by a conventional method.
11 is a cross-sectional view showing an example of a fusion bonded state after the secondary resin is injected and filled into the primary molded product bonding groove shown in FIG.
FIG. 12 is a cross-sectional view showing an example of various shapes of weld peaks provided on the surface of the primary molded product of the joining groove.
FIG. 13 is a diagram of a pressure test apparatus.
14 is a joint cross-sectional view showing a fracture surface after a pressure resistance test of Comparative Example 1. FIG.
15 is a joint cross-sectional view showing a fracture surface after a pressure resistance test of Example 1. FIG.
[Explanation of symbols]
1 Divided portion 1 '(of the primary molded product) Divided portion 2' (of the primary molded product) 2 Butted portion 2 'Butted portion 3 (of the primary molded product) Joining groove portion 3' (of the primary molded product) Part 4 Hollow part 5 Abutting surface 6 Joining groove 7 (configured by combining the joining groove parts of the primary molded product) Groove side part 7 ′ of the abutting surface 5 Hollow side part 8 of the abutting surface 5 Joining flange part 8 ′ Joining flange portion 9 Joining flange 10 (configured by combining joining flange portions) Joining groove bottom surface portion 10 '(primary molded product) Joining groove top surface portion 11 Joining groove butting surface Side vertical wall portion 12 Parting surface side vertical wall portion 17 of the joining groove Secondary sprue gate 18 for secondary forming Secondary runner 19 for secondary forming 20 Gate 20 for secondary forming Injection joining to the joining groove by secondary forming Resin part 21 fixed Mold 21 ′ Moving mold 22 Mold parting surface 23 Hydraulic cylinder drive unit 24 Pipe 25 Closing plate 26 Product precursor 27 Molded product 28 Weld pile 28 ′ Weld pile 29 Corner 30 (of weld groove) Bonding groove corner 30 ′ (provided in the bonding groove corner 30) R 31 (on the vertical wall portion 11 side of the weld wall closest to the vertical wall portion 11) corner 32 (on the weld wall) Base length 33 (weld mountain) corner interval 34 (weld mountain) height 35 Distance between weld wall corner closest to the vertical wall portion 11 and vertical wall portion 11 36 Primary molded product and secondary molded resin A portion 37 corresponding to the valley of the welding peak of the primary molded product in which the primary molded product and the secondary molded resin are not fused with each other at the joining and welding surface of the butt surface side vertical wall portion 11 of the primary molded product joining groove. In the bonded and fused surface between the primary molded product and the secondary molded resin, The portion where the primary molded product and the secondary molded resin are not fused 38 The surface of the primary molded product is re-melted by the heat of the secondary molded resin at the joint fusion surface of the primary molded product and the secondary molded resin. The welded portion 39 The basic shape of the weld pile provided on the surface of the joining groove of the primary molded product having a sharp apex of the welding peak 40 The surface of the joining groove of the primary molded product having the flat top of the weld mountain The basic shape 41 of the weld pile provided in the base shape 42 of the weld mountain provided on the surface of the joining groove of the primary molded product having the R shape at the top of the weld mountain 42 Nipple 43 Pressure pump 44 Fracture surface 45 after the pressure resistance test of Comparative Example 1 Fracture surface after pressure resistance test of Example 1

Claims

A joining groove portion (3) provided inside the butting portion (2), the joining flange portion (8), and the joining flange portion (8) is divided into two or more parts in the primary molding die. Each divided part (1) of the primary molded product having is abutted in each of the abutting parts (2), the joining flange part (8), and the joining groove part (3) by abutting in the secondary molding die. (5) A joining flange (9) and a joining groove (6) are formed to obtain a product precursor (26) having a hollow portion, and a secondary resin is added to the joining groove (6) of the product precursor (26). In a primary molding die for filling to form a bonded resin portion (20) and bonding the product precursor (26) to obtain a molded product (27),
In the joining groove corner (30) constituted by the bottom surface portion (10) and the top surface portion (10 ') of the joining groove (6) and the abutting surface side vertical wall portion (11), an R rating of R 0.5 mm or more, or A primary molding die having a C surface (cut surface) of 5 mm or more.

The mold for primary molding according to claim 1, wherein welding peaks (28) are provided on the bottom surface portion (10) and the top surface portion (10 ') of the joining groove (6).

The length of the corner (31) between the side surface facing the vertical wall portion (11) side of the weld pile (28) closest to the vertical wall portion (11) and the bottom surface portion (10) or the top surface portion (10 '). The mold for primary molding according to claim 2, wherein the distance from the wall portion (11) is 1 to 4 mm.

The mold for primary molding according to claim 2 or 3, wherein a corner interval (33) between adjacent weld piles (28) is 0.2 to 3 mm.

5. The corners (29) and (31) between the both side surfaces of the weld pile (28) and the bottom surface portion (10) or the top surface portion (10 ′) are provided with a radius of R 0.3 mm or more. The primary molding die according to any one of the above.

A product precursor (30) by abutting each divided part (1) of the primary molded product formed by dividing into two or more in the primary molding die according to any one of claims 1 to 5. A mold for secondary molding is obtained in which the bonding groove (6) of the product precursor (30) is filled with resin to form the bonding resin portion (20).

The secondary molding die according to claim 6, which is obtained by sliding or rotating the primary molding die.

A molding in which a primary molded product is molded with the primary molding die according to any one of claims 1 to 5, and a secondary resin is injected and filled into a joining groove (6) of the primary molded product to be integrated. Method.

The molding method according to claim 8, wherein hollow body molding is performed using a die slide injection method or a die rotary injection method.

A molded product obtained by the molding method according to claim 8 or 9.