JP3775376B2 - Insert product molding method and insert product molding apparatus - Google Patents

Description

【００４８】
また、上記実施形態では、保持ピン２を後退させた後、保持ピン２の加熱を停止していた。しかし、溶融樹脂６が保持ピン２と金型１の間のクリアランスに侵入して固化し、その後の保持ピン２の動作が不能になることがある。この場合、保持ピン２の動作時に再び加熱を行うことにより、保持ピン２と金型１の間のクリアランスにある樹脂を再溶融させ、保持ピン２の動作を復帰させることができる。
【００４９】
以上の説明では、保持ピンの加熱方法として、保持ピン自体に発熱体を備え、直接的に保持ピンを加熱するようにしたものについて説明したが、保持ピンの加熱方法はこれに限るものではなく、例えば型の保持ピンが装着される周辺に電気等によるヒータ部を設けるようにして間接的に保持ピンを加熱するようにしてもよい。ただし、この場合には、上述した電気ヒータにより直接保持ピンを加熱する場合に比べ、発熱体が保持ピンから離れているため、保持ピンを十分に加熱できないという問題がある。
【００５０】
また、保持ピン自体を電気ヒータにて直接加熱するのではなく、例えば試験ピンＢのように保持ピンの本体を空洞状態として、その内部に圧力や温度を加えることで高温状態とされた水、空気、油等の媒体を保持ピンの空洞部に供給することで、保持ピンを加熱することも考えられる。ただし、この場合には、保持ピンを電気ヒータにて加熱する場合に比べて、媒体の特性上、温度上昇はあまり期待できない。また、媒体の温度を上げるためには高圧にする必要があるため、保持ピンには、その圧力に耐えうることも条件となるため、構造的にそのための工夫が必要となるという欠点がある。
【００５１】
また、以上の説明では、保持ピンを昇温させた後の降温については何ら触れていなかったが、自然に温度が下がるようにしてもよいし、あるいは成形サイクルを速めるために、保持ピン周辺に降温手段を設けるようにしてもよい。降温手段としては、例えば、図２（ｄ）で示したような型の温度を設定するための温度供給媒体８２の流路８３のような冷却経路を保持ピン付近に設け、この冷却経路に水などの冷却媒体を流すようにして、加熱された保持ピンを強制的に冷却することが考えられる。
【００５２】
また、保持ピンの加熱後の温度については、図１２に示すように樹脂の融点温度とすることが望ましい。しかし、保持ピンの温度を必ずしも樹脂の融点以上にする必要はない。少なくとも型の温度よりも高くすれぱよいのである。すなわち、図８において説明したように、従来では保持ピン自体に温度に関しては何も施されておらず、その温度は高くてもせいぜい型の温度と同じになっていた。型の温度は注入された溶融樹脂をキャビティ内に導入できて、かつ注入された溶融樹脂を固めるための温度に調整されているため、溶融樹脂は保持ピンによっても冷却されることになる。この状態でインサート品の樹脂成形を行うと、溶融樹脂が保持ピンにより冷却固化されていたため、保持ピンを後退させたときに、保持ピン周りで冷却固化された樹脂により、ピン穴を十分に埋め込むことができず、未融合部が残留してしまっていた。
【００５３】
つまり、ピン穴が十分に埋め込まれなかったのは、保持ピン周りの樹脂が保持ピンにより冷却されて固くなったためであり、その固くなった樹脂を柔らかくできれば、図８（ｄ）に示すように従来に比べてより未融合部の残留を抑制することができ、信頼性を向上させることができる。従って保持ピンの温度を樹脂の融点以上に上げることは、必ずしも必要ではない。図１２に示したような樹脂の変形温度まで加熱するようにすれば効果は十分得られるものと考える。
【００５４】
例えば、注入樹脂が熱可塑性樹脂であるＰＢＴ（ポリブチレンテレフタレート）の場合には、ＰＢＴの融点は２３０℃であり、また、ＰＢＴの熱変形温度は１５０℃であり、型温は７０℃〜８０℃程度に設定される。従って、保持ピンの加熱温度は、１００℃に加熱することで、保持ピン周りの樹脂は、保持ピンを加熱しない場合に比べて柔らかい状態とされ、図８（ｄ）に示すようにピン穴に起因する未融合部の残留を、保持ピンを加熱しない場合に比べて抑制することができると考えられる。また、ＰＢＴの熱変形温度である１５０℃まで保持ピンを加熱すれば、保持ピン周りの樹脂は十分変形可能な状態にあるため、ピンに起因する未融合部の残留を十分抑制することができるものと考える。そして、保持ピンの温度をＰＢＴの融点以上に加熱すれば、保持ピン周りの樹脂は冷却固化されていたとしても保持ピンにより溶けうる状態にされるため、保持ピンを後退させた後のピン穴に起因する未融合部の残留をほとんどなくすことができる。
【００５５】
〔実施形態２〕
図１５は本実施形態に係るインサート品成形装置の要部断面図である。
【００５６】
本実施形態の成形装置は、図１５に示すように、上型１１１及び下型１１２よりなり薄肉形成部１１５を有する金型１０１と、加熱手段を具備し金型１０１に進退動自在に設けられた２本の保持ピン１０２とを備えている。なお、本実施形態での薄肉形成部１１５は、請求項１５、１８でいう隆起部のことである。金型１０１は、閉じられた上型１１１と下型１１２とが対向する面によって形成された成形品の外周形状と対応するキャビティ１１３を有する。また、金型１０１の一側面には、キャビティ１１３内に溶融樹脂を充填するゲート１１４が設けられている。そして、上型１１１及び下型１１２の型面には、キャビティ１１３内に配置されたインサート品１０５の両端部と対応する位置に上下型面より相対向して突出する薄肉形成部１１５が設けられている。この薄肉形成部１１５は、その先端面がインサート品１０５の表面と近接して対向し、その間の寸法が約１ｍｍとなるように設定されている。一方、薄肉形成部１１５以外の部分（保持ピン１０２の周り）の型面とインサート品１０５の表面との間の寸法は約４ｍｍとなるように設定されている。これにより、薄肉形成部１１５とインサート品１０５との間に充填される溶融樹脂の肉厚が薄肉形成部１１５の突出している分（約３ｍｍ）だけ他の部分よりも薄くなるように設定されている。
【００５７】
保持ピン１０２は、上型１１１及び下型１１２の中央部に縦方向に嵌挿された状態でそれぞれ１本づつ設置され、キャビティ１１３内に向かって進退動自在に設置されている。各保持ピン１０２には、キャビティ１１３内に配置されるインサート品１０５を先端で保持する位置と、先端面がキャビティ１１３を形成する型面と一致する位置との間を進退駆動するエアシリンダ（図示せず）が設けられている。この保持ピン１０２は、絶縁性セラミックからなり、その内部にはセラミック製の発熱体からなる電気ヒータ１２１が埋設されている。各電気ヒータ１２１は、それぞれ電源１０３に接続されている。
【００５８】
以上のように構成された本実施形態の成形装置によりインサート成形を行うには、先ず、金型１０１を開いた状態で各保持ピン１０２を突出させ、下型１１２の保持ピン１０２上にインサート品１０５をセットする。次に金型１０１を閉じると、図１５に示すように、インサート品１０５が各保持ピン１０２の先端で保持されて、キャビティ１１３内の所定位置に配置される。
【００５９】
この状態で、図１６に示すように、金型１０１のキャビティ１１３内に射出成形機（図示せず）によりゲート１１４を介して溶融樹脂１０６を充填する。同時に、電源１０４のスイッチオンにより、電気ヒータ１０３に電流を供給し、各保持ピン１０２を溶融樹脂の融点以上の温度に加熱する。この際、インサート品１０５は保持ピン１０２で固定されているため、溶融樹脂１０６の流動抵抗や圧力によって移動することはない。そして、一定時間経過すると、図１７に示すように、溶融樹脂１０６は金型１０１との接触面及びインサート品１０５との接触面から次第に冷却固化が進行し、薄肉形成部１１５の部分に充填された溶融樹脂１０６は肉厚が薄いため肉厚中心まで短時間で固化が進行するが、他の部分に充填された溶融樹脂１０６の肉厚中心部は溶融したままの状態になっている。また、キャビティ１１３内に充填された溶融樹脂１０６が保持ピン１０２に接触しても、保持ピン１０２が溶融樹脂１０６の融点以上の温度に加熱されているため、保持ピン１０２の周囲の樹脂には冷却固化層は生成しない。
【００６０】
そして、溶融樹脂１０６の充填が完了した後、エアシリンダを駆動して各保持ピン１０２をそれらの先端面がキャビティ１１３を形成する型面と一致する位置まで後退させた後、必要に応じて更に溶融樹脂１０６を充填するとともに、保持ピン１０２を後退させた後は保持ピン１０２を加熱する必要がないため、電気ヒータ１０３への通電は停止する。これにより、図１８に示すように、保持ピン１０２を抜き去った後の各ピン穴に周囲の溶融樹脂１０６が流入し、保持ピン１０２に起因する未融合部も残留することなく封止される。このとき、インサート品１０５は、薄肉形成部１１５の部分で既に固化した樹脂によって固定されるため位置ずれしない。その後、キャビティ１１３内に充填された溶融樹脂１０６の全体が冷却固化することにより、インサート品１０５が樹脂により十分に封止された防水性の高い成形品が形成される。
【００６１】
以上のように、本実施形態のインサート品成形装置によれば、本実施形態の金型１０１には、キャビティ１１３内に配置されたインサート品１０５の表面と近接して対向し、その間隙に充填される溶融樹脂１０６の肉厚を薄く形成する薄肉形成部１１５が設けられているため、保持ピン１０２を後退させるときに、薄肉形成部１１５の部分で既に冷却固化した樹脂によってインサート品１０５が固定されるので、インサート品１０５の位置づれを防止することができる。
【００６２】
また、保持ピン１０２は、キャビティ１１３に溶融樹脂１０６が充填されるときに溶融樹脂１０６の融点以上の温度に保持ピン１０２を加熱する加熱手段を具備しているため、溶融樹脂１０６の充填が完了するまでインサート品１０５を保持ピン１０２で保持してインサート品１０５の位置づれを防止することができ、かつ、保持ピン１０２を後退させるときには、保持ピン１０２の周囲に樹脂の冷却固化層が生成しないので、保持ピン１０２に起因する未融合部が残留することがなく、インサート品１０５を十分に封止した樹脂成形品を形成することができる。
【００６３】
尚、上記実施例では、薄肉形成部１１５と加熱される保持ピン１０２の両方を用いてインサート品１０５を樹脂成形したが、保持ピン１０２を加熱せずに薄肉形成部１１５のみによっても保持ピン１０２を後退させたときのピン穴に起因する未融合部の残留を抑制することができる。このことを図１９を用いて説明する。
【００６４】
図１９は、成形中において保持ピン１０２を後退させたときのキャビティ１１３内でのインサート品１０５の傾きと、保持ピン１０２を後退させたときのピン穴に起因する未融合部の長さ（図８参照）を示すものであり、インサート品１０５の傾きをａ₀，ａ₁で示し、未融合部の長さをｂ₀，ｂ₁で示す。尚、インサート品１０５の傾きにおいて、ａ₀は本実施形態のように薄肉形成部１１５のない従来の場合の傾きを示し、またａ₁は本実施形態のように薄肉形成部１１５を用いた場合の傾きを示す。
【００６５】
また、未融合部の長さにおいて、ｂ₀は保持ピン１０２を加熱させずに保持ピン１０２を後退させたときに残留する未融合部の長さを示すものであり、ｂ₁は実施形態１のように保持ピン１０２を加熱させて保持ピン１０２を後退させたときに残留する未融合部の長さを示すものである。図１９において、ａ₀，ａ₁を見ても分かるようにインサート品１０５の傾きは、樹脂注入が開始された直後に保持ピン１０２を後退させたときはその傾きは大きく、樹脂の注入が完了する直前からその傾きが急激に小さくなる。これは、樹脂の充填によりインサート品１０５の位置決めが行われるようになるからである。
【００６６】
また、ｂ₀，ｂ₁を見ても分かるように未融合部の長さは、樹脂の注入が進行するのに従って、保持ピン１０２を後退させるタイミングが遅くなると、その長さが長くなる。これは、保持ピン１０２を後退させるタイミングが遅くなると、注入された樹脂が保持ピン１０２の周りで固化されるようになるためである。ここで、製品の仕様として傾き限界と未融合部の長さ限界が図１９に示すように決められている場合を想定する。
【００６７】
従来のように、薄肉形成部１１５を用いない場合であっても、また保持ピン１０２を加熱しない場合では、傾きａ₀はＡ₀のタイミング以後で保持ピンを後退させる必要があり、また未融合部の長さｂ₀はＢ₀のタイミング以前で保持ピン１０２を後退させる必要があり、図からわかるように両者を満たすような保持ピン１０２を後退させるタイミングが存在しない。
【００６８】
そこで、本実施形態のように薄肉形成部１１５を用いることで、インサート品１０５の傾き状態が従来のａ₀からａ₁へシフトすることになり、より早いＡ₁のタイミングにて保持ピン１０２を後退させることが可能となり、これによりインサート品１０５の傾きと未融合部の長さの両方を満たす製品を製造することが可能となる。
【００６９】
すなわち、図１９からもわかるように、薄肉形成部１１５を用いてインサート品１０５を樹脂成形することで、インサート品１０５の傾きに対して保持ピン１０２を後退させるタイミングを速めることができ、従って、従来より早いタイミング（Ａ₀より早いタイミング）で後退させることにより、未融合部の長さを短くすることができるようになる。
【００７０】
よって、薄肉形成部１１５を用いることで、保持ピン１０２に起因する未融合部の残留を抑制することができる。ただし、薄肉形成部１１５は保持ピン１０２以外の領域に設ける必要がある。つまり、保持ピン１０２の周辺の樹脂の肉厚は従来のままにして、保持ピン１０２の周辺以外の領域にて薄肉形成領域を設けるようにし、保持ピン１０２周辺の樹脂の固化は従来のままであって、薄肉形成領域では樹脂がより速く固化させるようにするのである。
【００７１】
さらに、保持ピン１０２を加熱させて後退させることで、保持ピン１０２を加熱せずに後退させる場合に比べて、保持ピン１０２を後退させるタイミングをより遅らせても未融合部の長さを短くすることができる。つまり、図１９において、ｂ₀をｂ₁にシフトさせることができ、より遅いタイミングで保持ピン１０２を後退させても未融合部の長さを短くすることができる。従って、保持ピン１０２をより遅く後退させることができるため、インサート品１０５の傾きを防止できる。
【００７２】
以上をまとめると、▲１▼薄肉形成領域を設けることで、保持ピン１０２をより早いタイミングで後退させることができ、これにより保持ピン１０２が後退した後のピン穴に起因する未融合部の残留を抑制することができる。図１９においては、Ａ₁からＢ₀の時間において保持ピン１０２を後退させることができる。
【００７３】
▲２▼保持ピン１０２を加熱することで、インサート品１０５の傾きを防止するために保持ピン１０２をより遅いタイミングで後退させたとしても、ピン穴に起因する未融合部の残留を抑制できる。図１９においては、Ａ₀からＢ₁の時間において保持ピン１０２を後退させることができる。
【００７４】
▲３▼薄肉形成領域を設け、保持ピン１０２を加熱することで、上記▲１▼▲２▼の効果が同時に得られるため、インサート品の傾きを十分抑制しつつ、保持ピンのピン穴に起因する未融合部の残留を抑制できる。図１９においては、Ａ₁からＢ₁の時間において保持ピン１０２を後退させることができる。
【００７５】
なお、金型１０１の薄肉形成部１１５とインサート品１０５の表面との間の寸法は、小さくする程その間に充填される溶融樹脂１０６の肉厚が薄くなり冷却固化が早まるのでインサート品１０５の固定能力は高くなるが、過度に小さくすると溶融樹脂１０６の充填不良が生じるため、０．５〜１．５ｍｍ程度に設定するのがよい。一方、薄肉形成部１１５以外の部分の型面とインサート品１０５の表面との間の寸法は、大きくする程ピン穴の封止が完全になるが、成形サイクルが長くなってしまうので、２〜６ｍｍ程度に設定するのがよい。
【００７６】
また、上記実施形態では、金型１０１の薄肉形成部１１５を型面から突出させることにより、薄肉形成部１１５とインサート品１０５の表面との間の寸法が小さくなるようにしているが、これとは逆に、インサート品１０５側に形成された凸部を利用したり、インサート品１０５に凸部を設けることにより、その間の寸法を小さくすることも可能である。この場合には、薄肉形成部１１５を型面から突出して設ける必要がないこともある。
【００７７】
これを図２０に示す。この図に示すように、インサート品１０５にインサート側薄肉形成領域１０５ａが設けられており、保持ピン１０２周りの成形樹脂厚よりもその厚さが薄くなるようにされている。また、この場合において、型の方に薄肉形成領域が設けられていてもよい。また、薄肉形成部１１５を設ける位置やその個数は、インサート品１０５の形状や大きさ等を考慮することにより適宜選択して設定することができる。
【００７８】
図２１に示すように、薄肉形成部１２５形状は様々なものが考えられる。図２１（ａ）は台形状であり、図２１（ｂ），（ｂ′）はかまぼこ形状であり、図２１（ｃ），（ｃ′）は半球形状をしている。尚、保持ピン１０２が後退した後のピン穴は、保持ピン１０２周りで冷却固化された樹脂を保持ピンで柔らかくする、あるいは溶かすことにより、ピン穴を塞ぐものであるが、注入されている樹脂圧も作用するものであるため、樹脂が注入されてくる方向に対して薄肉形成部１１５が保持ピン１０２の前方にあると、保持ピン１０２が後退したピン穴に樹脂圧が十分伝わらないため、それを避けるために、樹脂の注入方向に対して保持ピンと薄肉形成部の位置をずらすようにすることが望ましい。
【００７９】
図２２を用いて説明すると、図２２（ａ）〜（ｃ）において、樹脂は紙面に対して紙面の表側から裏側へ注入されるものとする。図２２（ａ）では、樹脂の注入方向に対して、薄肉形成部１３５が保持ピン１３２よりも前に位置するため、ピン穴に樹脂圧が伝わりにくく好ましくない。図２２（ｂ），（ｃ）のように樹脂の注入方向に対して、薄肉形成部１３５と保持ピン１３２の位置をずらすようにするとよい。
【００８０】
また、図２３（ａ）に示すように、薄肉形成部１４５を樹脂の注入方向に対して、保持ピン１４２よりも後ろ側に配置してもよい。尚、図２３（ｂ）は図２３（ａ）の矢印方向の断面図を示すものであり、薄肉形成部１４５は、インサート品１４０に対して１周するようにキャビティ１４３内に突出させるようにしたものである。当然、この薄肉形成部１４５に代替する薄肉形成部がインサート品１４０側に設けられていてもよい。
【００８１】
なお、半導体ＩＣを用いた磁気検出装置の一つとして、セラミック基板上に半導体ＩＣやコンデンサ等を搭載したハイブリッドＩＣがあるが、このハイブリッドＩＣのセンサ素子の防水、防油対策として、上記実施形態１および実施形態２の成形装置を用いてインサート成形を行い、その表面を樹脂封止することが考えられる。しかし、そのハイブリッドＩＣをインサート品して一体樹脂成形を行うと、樹脂成形圧が高圧（通常２０〜８０ＭＰａ）であるため、応力によりセラミック基板に割れが発生するという問題がある。
【００８２】
そこで、セラミック基板に割れが生じない樹脂成形圧（６〜８ＭＰａ）にて、セラミック基板の一端に配置されたセンサ素子を含めてモールド材（流動性の高いエポキシ材等）で一次成形することにより形成したモールドＩＣをインサート品として用いれば、セラミック基板に割れが発生することなく上記実施形態１及び実施形態２の成形装置によりインサート成形を行うことが可能となる。
【００８３】
このようにして作製される磁気検出装置は、例えば図２４及び図２５に示すように、一端側にセンサ素子１５１が埋設された板状のモールドＩＣ１５２と、モールドＩＣ１５２が嵌着される貫通孔を有する筒状の中空磁石１５３と、中空磁石１５３及びモールドＩＣ１５２を封止する成形樹脂部１５４とからなり、優れた防水性、防油性を有する。
【００８４】
〔実施形態３〕
図２６は本実施形態に係るインサート品成形装置の断面図であり、図２７（ａ）（ｂ）は本実施形態で用いるインサート品の組付け状態を示す説明図であり、図２８は本実施形態のインサート品成形装置により作製される磁気検出装置の構成図である。
【００８５】
本実施形態の成形装置は、図２７（ｂ）に示すように、貫通孔をもつ筒状の中空磁石２５１とその中空磁石２５１の貫通孔内に圧入嵌着された検知装置２５２とからなる一体品をインサート品２０５に用いてインサート成形することにより、そのインサート品２０５を樹脂で封止した磁気検出装置を作製するものである。このインサート品２０５は、図２７（ａ）に示すように、検知装置２５２のデータムＡが中空磁石２５１のデータムＢに合うまで圧入することにより、検出装置１５２の出力特性が最も優れる距離（中空磁石２５１の着磁面から検知装置２５２の先端面までの距離）ｅを決める構造のものである。
【００８６】
本実施形態の成形装置は、図２６に示すように、左右方向に開閉可能に構成された固定型２１１及び可動型２１２よりなる金型２０１と、加熱手段を具備し金型２０１に進退動自在に設けられた４本の保持ピン２０２と、加熱手段を具備し金型２０１に進退動自在に設けられた２本の支持ピン２０７とを主要素として構成されている。
【００８７】
金型２０１は、閉じられた固定型２１１と可動型２１２とが対向する面によって形成された成形品の外周形状と対応するキャビティ２１３を有する。また、金型２０１の上方両端には、キャビティ２１３内に溶融樹脂（図示せず）を充填するゲート２１４が設けられている。保持ピン２０２は、金型２０１の側面略中央部に横方向に嵌挿された状態で固定型２１１及び可動型２１２にそれぞれ２本づつ設置されており、キャビティ２１３内に向かって進退動自在に設けられている。各保持ピン２０２には、キャビティ２１３内に配置されるインサート品２０５の中空磁石２５１の側面をその先端で保持する位置と、先端部がキャビティ２１３を形成する型面に略一致する位置との間を進退駆動するエアシリンダ（図示せず）が設けられている。この保持ピン２０２は、絶縁性セラミックで円柱状に形成され、その内部にはセラミック製の発熱体からなる電気ヒータ２０３が埋設されている。各電気ヒータ２０３は、固定型２１１側と可動型２１２側とにそれぞれ設置された電源２０４に接続されている。
【００８８】
支持ピン２０７は、金型２０１の下面略中央部に縦方向に嵌挿された状態で固定型２１１及び可動型２１２のそれぞれ１本づつ設置されており、キャビティ２１３内に向かって進退動自在に設けられている。各支持ピン２０７には、キャビティ２１３内に配置されるインサート品２０５の中空磁石２５１及び検知装置２５２の下端面を同時にその先端面で支持する位置と、先端部がキャビティ２１３を形成する型面に略一致する位置との間を進退駆動するエアシリンダ（図示せず）が設けられている。この支持ピン２０７は、絶縁性セラミックで円柱状に形成され、その内部にはセラミック製の発熱体からなる電気ヒータ２０８が埋設されている。各電気ヒータ２０８は、電源２０９に接続されている。
【００８９】
以上のように構成された本実施形態の成形装置によりインサート成形を行うには、先ず、キャビティ２１３内に左右方向からそれぞれ突出させた保持ピン２０２によりインサート品２０５の中空磁石２５１の設けられたピン受け用の窪みに差し込み固定する。次に、下方からキャビティ２１３内に突出させた２本の支持ピン２０７の先端面でインサート品２０５の中空磁石２５１及び検知装置２５２の下端面を同時に支持する。このとき、検知装置２５２の先端面と磁気検出装置の下端面との間の距離ｆが耐久試験で確認されたクラックの発生しないモールド樹脂の最小の厚さとなるようにインサート品２０５の上下方向の位置決めをする。
【００９０】
この状態で、金型２０１のキャビティ２１３内に射出成形機（図示せず）によりゲート２１４を介して高圧（２０〜８０ＭＰａ）の溶融樹脂を充填する。同時に、電源２０４、２０９のスイッチオンにより、保持ピン２０２及び支持ピン２０７の各電気ヒータ２０３、２０８に電流を供給し、各保持ピン２０２及び各支持ピン２０７を溶融樹脂の融点以上の温度に加熱する。このとき、インサート品２０５の中空磁石２５１は左右方向から４本の保持ピン２０２で保持され、かつ中空磁石２５１及び検知装置２５２の下端面が同一の支持ピン２０７で溶融樹脂が充填されるゲート２１４とは逆の方向から同時に支持されているため、溶融樹脂の高い注入圧がインサート品２０５に加わって中空磁石２５１と検知装置２５２の圧入力を越えても、中空磁石２５１と検知装置は互いに位置づれすることがない。
【００９１】
また、キャビティ２１３内に充填された溶融樹脂が保持ピン２０２に接触しても、保持ピン２０２が溶融樹脂の融点以上の温度に加熱されているため、保持ピン２０２の周囲の樹脂に冷却固化層は生成しない。次に、エアシリンダを駆動して、各保持ピン２０２及び各支持ピン２０７をそれらの先端面がキャビティ２１３を形成する型面と一致する位置まで後退させ、その後は保持ピン２０２及び各支持ピン２０７を加熱する必要がないため、各電気ヒータ２０３、２０８への通電を停止する。これにより、各保持ピン２０２及び各支持ピン２０７を抜き去った後のピン穴にその周囲の溶融樹脂が流入して完全に融合し、ピン穴は完全に消滅して残留しない。その後、キャビティ２１３内の溶融樹脂が冷却固化することにより、図２９に示すような、中空磁石２５１及び検知装置２５２が位置づれすることなく所定の距離寸法ｅ、ｆが確保され、出力特性の優れた磁気検出装置が形成される。
【００９２】
以上のように、本実施形態の成形装置によれば、キャビティ２１３内に配置されるインサート品２０５の中空磁石２５１及び検知装置２５２の下端面を同時に支持する支持ピン２０７が設けられているため、高圧で注入される溶融樹脂の圧力により中空磁石２５１及び検知装置２５２が位置づれするのを防止することができ、これにより出力特性の優れた磁気検出装置を形成することができる。
【００９３】
尚、本実施形態において、インサート品２０５の中空磁石２５１を図２７に示すように保持ピン２０３の先端が中空磁石２５１の凹部２５１ａに嵌合してインサート品２０５を保持するようにしているが、このようにすることでインサート品の位置合わせが確実に行えるため、形成されたときの成形品内部のインサート品の位置がより確実に設定できるようになり、より信頼性の高いインサート成形品を提供することができる。さらに、凹部２５１ａがテーパ状となっており、保持ピン２０３をその凹部２５１ａに導入するような形状になっていると、さらに位置決めの精度が向上する。
【００９４】
また、図２７に示すように保持ピン２０２の先端が尖っていると、保持ピン２０２がインサート品に突き刺さってしまい、それ以上インサート品が動くことができず、正確に位置決め出来ない可能性があるため、これを防ぐために、例えば図１４に示すようにある程度テーパの部分を残して先端を平坦化することが望ましい。また、先端が半球状になっていてもよい。
【００９５】
尚、以上のことは、本実施形態に限らず、上記実施形態１、２についても適用可能である。尚、本発明におけるインサート品とは、成形後に樹脂に埋め込まれる部品のことをいう。例えば、インサート品が成形品の表面に一部表出するもの、あるいは電気コイルやＩＣ部品やサーミスタなどの電気部品であって、その表面を樹脂により十分に封止するのが好ましい種々のものが対象となる。ただし、外部との電気接続を行うための配線やコネクタ等は、当然、成形品の外部へ露出するものである。
【００９６】
本発明における型は、内部にインサート品が配置され、その成形品の外周形状と対応するキャビティを有するものである。この場合のキャビティとは、成形用の型において成形品に該当する空間部分のことをいう。この型は、キャビティ内へのインサート品の配置や、成形品の取出しを行うため、上下方向に開閉可能に構成された上型及び下型よりなるもの、あるいは左右方向に開閉可能に構成された固定型及び可動型よりなるものなど従来と同様のものを用いることができる。尚、型としては、通常は金属からなる金型が用いられる。
【００９７】
また、型に設けられる保持部材は、インサート品をキャビティ内の定位置に保持するものであり、型からキャビティ内へ突出・後退できるように構成される。この保持部材の動作は油圧シリンダ、エアシリンダ等の駆動装置によって行うことができる。保持部材の形状としては、一般的に丸棒を用いるが、インサート品の形状に合わせて、角棒あるいはＬ字状等にするのも自由である。なお、保持部材の先端面は、保持部材がキャビティから後退したときに、型の型面とともにキャビティを形成する面となる。保持部材の材質としては、通常は金型用鉄鋼材料を用いるが、後述の加熱手段の加熱に耐え得るように、セラミック材料を用いてもよい。
【００９８】
すなわち、型というのは注入された溶融樹脂を冷却固化させるためのものであり、一方、加熱手段により加熱された保持部材は、保持部材周りの樹脂の固化を防ぐ、あるいは固化した樹脂を溶融状態に近づけるものである。本発明における加熱手段は、加熱の程度としては、保持部材の周囲の樹脂を溶融状態に保てればよく、型のキャビティ表面温度よりも高い温度状態とされれば、保持部材に起因する上記未融合部の残留を抑制する効果を発揮するものである。好ましくは、その樹脂の融点以上で熱劣化温度以下に設定する。この加熱手段としては、電源からの電流の供給により発熱する電気ヒータ（例えばニクロム線、タングステン線、プラチナ線、導電性セラミック等）を用いることができる。電気ヒータの設置位置としては、保持部材を迅速に加熱するために保持部材内部が最も良いが、保持部材内部でのスペースの制約がある場合は、保持部材の外部から熱伝導により加熱するようにしてもよい。電気ヒータ用電源としては、一般的には、スイッチング電源等、大電流を一定電流値で供給できるものが好ましい。電源の使用台数としては、保持部材１本につき１台使用すると、保持部材１本毎の温度調節ができて良いが、厳密な温度コントロ−ルを必要としない場合は、複数の保持部材を１台の電源で加熱しもよい。なお、保持部材は１本でも２本以上の複数本使用してもよい。
【００９９】
本発明の成形装置は、熱可塑性樹脂を用いてインサート成形を行うのに好適なものである。熱可塑性樹脂としては、例えばＰＢＴ（ポリブチレンテレフタレート）、ＰＰＳ（ポリフェニレンスルフィド）、ポリアミド系、ポリエステル系など種々のものを用いることができる。
【図面の簡単な説明】
【図１】 実施形態１に係る射出成形機の正面図である。
【図２】 実施形態１に係る射出成形機の一部を拡大して示す透視図である。
【図３】 実施形態１に係る射出成形機の型を開いた状態を示す正面図である。
【図４】 実施形態１に係るインサート品成形装置の断面図である。
【図５】 実施形態１に係るインサート品成形装置の成形工程における断面図である。
【図６】 実施形態１に係るインサート品成形装置の成形工程における断面図である。
【図７】 実施形態１に係るインサート品成形装置の成形工程における断面図である。
【図８】 樹脂成形品に保持ピンに起因する未融合部が残留する状態を示す説明図でる。
【図９】 保持ピンによるインサート品の保持方法を示す説明図である。
【図１０】 保持ピンによるインサート品の保持方法を示す説明図である。
【図１１】 保持ピンによるインサート品の保持方法を示す説明図である。
【図１２】 成形工程おける時間の経過と保持ピンの温度変化との関係を示すモデル図である。
【図１３】 （ａ）（ｂ）（ｃ）（ｄ）実施形態１において試験に用いた各保持ピンの構造を示す説明図である。
【図１４】 （ａ）（ｂ）（ｃ）実施形態１に係る加熱手段を有する保持ピンの外観図、透視図および断面図である。
【図１５】 実施形態２に係るインサート品成形装置の断面図である。
【図１６】 実施形態２に係るインサート品成形装置の成形工程における断面図である。
【図１７】 実施形態２に係るインサート品成形装置の成形工程における断面図である。
【図１８】 実施形態２に係るインサート品成形装置の成形工程における断面図である。
【図１９】 成形中において保持ピンを後退させたときのキャビティ内でのインサート品の傾きとピン穴に起因する未融合部の長さとの関係を示す説明図である。
【図２０】 実施形態２においてインサート品に薄肉形成領域が設けられている場合の説明図である。
【図２１】 （ａ）（ｂ）（ｂ′）（ｃ）（ｃ′）実施形態２において金型に設けられる種々の薄肉形成部の形状を示す説明図である。
【図２２】 （ａ）（ｂ）（ｃ）実施形態２において金型に設けられる薄肉形成部と保持ピンとの位置関係を示す説明図である。
【図２３】 （ａ）（ｂ）実施形態２において金型に設けられる薄肉形成部と保持ピンとの位置関係を示す説明図である。
【図２４】 実施形態１、２に係るインサート品成形装置により樹脂成形される磁気検出装置の一部断面正面図である。
【図２５】 実施形態１、２に係るインサート品成形装置により樹脂成形される磁気検出装置の一部断面平面図である。
【図２６】 実施形態３に係るインサート品成形装置の断面図である。
【図２７】 （ａ）（ｂ）実施形態３に係るインサート品の組付け状態を示す説明図である。
【図２８】 実施形態３に係るインサート品成形装置により作製される磁気検出装置の構成図である。
【符号の説明】
１、１０１、２０１…金型
２、５２、９２、１０２、１３２、１４２、２０２…保持ピン（保持部材）
３、１０３、２０３、２０８…電気ヒータ（加熱手段）
４、１０４、２０４、２０９…電源（加熱手段）
５、５５、９０、１０５、１４０、２０５…インサート品
６、５７、１０６…溶融樹脂
１１、１１１…上型
１２、１１２…下型
１３、７６、９１、１１３、２１３…キャビティ
１４、１０４、２０４…ゲート
２０…ピン穴
２１、２３、２７…保持ピン本体
２２…絶縁部材
２４、２６…発熱体
２５…絶縁材
２８、３３…金属キャップ
３１…セラミックスヒータ部
３２…金属スリーブ
３４、３５…電線
７０…台座
７１…ホッパー
７２…射出機
７３…型取付盤
７４…型開閉装置
７５…スプル
７７…ゲート
７８…イジェクターピン
７９…ヒータ部
８０…孔
８１…金属ヒータ
８２…温度供給媒体
８３…流路
９３…ランナー部
９４…連結部
９５…シリンダー
９６…連結部配線孔
９７…型部配線孔
９８…配線
９９…電源
６０…樹脂
６１、６２…未融合部
７２…射出機
１０５ａ…薄肉形成領域
１１５、１２５、１３５、１４５…薄肉形成部（隆起部）
１１５ａ…テーパ部
２０７…支持ピン
２１１…固定型
２１２…可動型[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an insert product molding method and an insert product molding apparatus for producing a molded product in which an insert product such as an electric coil, an IC component, or a thermistor is sealed with a resin.
[0002]
[Prior art]
Conventionally, for example, electrical coils and IC components need to be waterproof, so that the surface is covered with a potting material or a sealing plug is added to ensure waterproofness. In recent years, in order to reduce the cost of products and improve recyclability, the surface has been sealed with resin, and this resin sealing uses an insert molding method that is inexpensive and has excellent mass productivity. ing. As a molding apparatus used for this insert molding, for example, as disclosed in Japanese Patent Application Laid-Open No. 55-91642, a mold having a cavity in which an insert product is disposed, and the mold is provided so as to be movable forward and backward. One having a plurality of holding pins for holding an insert at the tip is known. When resin molding is performed with this molding device, the insert is held and held at a predetermined position in the cavity, and after filling the cavity with molten resin in that state, the holding pin is retracted from the cavity, Thereafter, the molten resin is further filled. Thereby, the molded product which sealed the whole surface of the insert product with resin is obtained.
[0003]
[Problems to be solved by the invention]
However, when molding is performed by the above-described conventional molding apparatus, if the timing of retracting the holding pin from the cavity is before the filling of the molten resin is completed (while the molten resin is flowing in the cavity), the pin of the holding pin Although the sealing of the hole is performed, the insert product is moved by the movement of the molten resin, and the thickness of the formed resin molded portion is not uniform, so that a good molded product cannot be obtained.
[0004]
Therefore, it is conceivable that the timing of retracting the holding pin from the cavity is after completion of filling of the molten resin, but although the movement of the insert product is small, a cooling solidified layer is already formed on the resin around the holding pin, Resin molded part that sufficiently seals the insert product because the resin that has flowed into the pin hole from the periphery of the holding pin does not completely fuse and fine moisture (hereinafter, unfused part) can enter. There is a problem that cannot be formed.
[0005]
The present invention has been devised in view of the above problems, and is a resin molding that sufficiently seals an insert product by suppressing the position of the insert product while suppressing the remaining unfused portion due to the holding pins. An object of the present invention is to provide an insert product molding method and a molding apparatus capable of forming a product.
[0006]
[Means for Solving the Problems]
In order to solve the above problem, the method described in claim 1 can be adopted. According to this means, in the molten resin injected into the cavity, in the region other than the holding member peripheral region, the region where the cooling is promoted as compared with the molten resin in the holding member peripheral region. Opposite to the insert Since it is provided, the solidification of the molten resin proceeds in this region in a shorter time than the region around the holding member. As a result, even when the holding member is retracted from the cavity at a timing before the molten resin around the holding member is sufficiently cooled and solidified, the insert product is fixed by the resin that has been solidified in the region where the cooling has been promoted. Therefore, position shift can be prevented. Therefore, it is possible to form a good resin molded product in which the insert product is sufficiently sealed while suppressing the misalignment of the insert product and the remaining unfused portion due to the holding member.
[0007]
Furthermore, according to the method of claim 2, the thickness of the region for promoting the cooling of the molten resin shown in claim 1 is thinner than the resin portion formed around the holding member by the molten resin. Therefore, this region can be obtained only by providing it on either the mold side or the insert product.
[0008]
Moreover, according to the method of Claim 3, even if it is an insert product which consists of the external component which has a hollow part, and the internal component inserted in the hollow part, an external component and an internal component are carried out by one holding member. Therefore, when the molten resin flows into the cavity, the displacement between the outer part and the inner part can be prevented by the inflow pressure of the molten resin.
[0009]
According to the fourth aspect of the present invention, in the molten resin injected into the cavity, in the region other than the holding member peripheral region, the region where the cooling is promoted compared to the molten resin in the holding member peripheral region. Opposite to the insert Therefore, it is possible to provide an insert molding apparatus that can obtain the above-described effect obtained by the method according to claim 1.
[0010]
Further, according to the means described in claim 5, in addition to the above-described effect by the means described in claim 4, the region for promoting the cooling of the molten resin is from the resin portion formed around the holding member by the molten resin. However, since it is a region raised in the cavity so that its thickness is reduced, there is an effect that this region can be easily formed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
Embodiment 1
First, a general injection molding machine will be briefly described with reference to FIGS. As shown in FIG. 1, the injection molding machine has an injection part for injecting molten resin on a pedestal 70 and a molding part for cooling and solidifying the molten resin injected from the injection part. Move in the direction of the arrow and inject molten resin into the mold.
[0013]
The injection unit includes a hopper 71 for putting pellet-shaped resin and an injection machine 72 for melting the resin on the pellet supplied from the hopper 71. When the pellet-shaped resin is supplied to the injection machine 72, the injection machine It is sent out to the tip end side of the injection machine 72 by a screw (not shown) in 72. And when it sends out to the front end side of the injection machine 72 with the screw in the injection machine 72, it is melted by the heater heat from the heater (not shown) provided in the injection machine 72 and the shear heat by the screw.
[0014]
The molding part includes a mold (molds A and B) for molding an insert product, a mold mounting plate 73 for holding the molds A and B, and a mold opening / closing device 74 for opening and closing the mold B. The mold B is opened and closed by the mold opening / closing device 74 in the direction of the arrow in the figure. FIG. 2A is an enlarged view of the portions of the molds A and B and the mold mounting board 73, and is partially a perspective view. The sprue 75 is a part for introducing the molten resin injected from the injection machine 72 into the cavity 76 in which the insert product is placed. The resin introduced into the mold is injected into the cavity 76 from the gate 77. When the molding of the insert product is completed, the mold B is separated from the mold A by the mold opening and closing device of FIG. 1 and the molded product can be taken out by the ejector pin 78.
[0015]
Usually, the mold is provided with a heater portion 79 for bringing the entire mold to a predetermined temperature, and the heater portion 79 is provided with a hole 80 in the mold as shown in FIG. A metal heater 81 is inserted, or as shown in FIG. 2 (c), a flow path 83 is provided for flowing a temperature supply medium 82 such as warm water or warm oil, and the mold is formed by flowing warm water or the like through the flow path 83. The temperature is kept at a predetermined temperature. In addition, as shown in FIG. 2D, there is a type in which the flow path 83 of the temperature supply medium 82 is divided. Although not shown, there may be a medium having a common inlet and outlet even if there are a plurality of flow paths as shown in FIG.
[0016]
In the above description, the mold is heated. However, depending on the type of resin to be injected, there are some which cool the mold. In that case, for example, cold water or the like is supplied as the temperature supply medium 82 as shown in FIGS. 2B and 2C. FIG. 3 is a view of the mold B when the molds A and B are opened. An insert product 90 is inserted into a cavity 91 forming a cavity 91 in a closed state with the mold A, and inserted by holding pins 92. The state which has hold | maintained the goods 90 is shown.
[0017]
A runner portion 93 in the figure is a path for introducing the molten resin from the sprue 75 to the gate 77, and is a portion where the molding resin remains as a so-called runner after molding. The molded product is transported to the next process after the runner is removed. The holding pin 92 is coupled to the cylinder pin 95a by the connecting portion 94, and the cylinder pin 95a moves up and down by the cylinder 95 using air pressure, hydraulic pressure or the like, so that the cavity 91 moves into the cavity 91. Can retreat from the cavity.
[0018]
In addition, since the holding pin 92 in this embodiment is heated by being energized, the connecting portion 94 is provided with a connecting portion wiring hole 96 and a mold portion wiring hole 97 in the mold, and the wiring 98 is provided. It is connected to a power source 99 located outside the mold. Next, features of the present invention will be described. FIG. 4 is a cross-sectional view of an essential part showing an example of an insert product forming apparatus according to the present embodiment. As shown in FIG. 4, the molding apparatus according to the present embodiment includes a mold 1 including an upper mold 11 and a lower mold 12, four holding pins 2 provided on the mold 1 so as to be movable back and forth, and a holding pin. And an electric heater 3 for heating 2 and a heating means including a power source 4 for supplying electric current to the electric heater 3. In the following embodiments, the holding member referred to in the claims will be described as a holding pin of an insert product.
[0019]
The mold 1 has a cavity 13 corresponding to the outer peripheral shape of a molded product formed by the surfaces of the closed upper mold 11 and lower mold 12 facing each other. A gate 14 for filling the cavity 13 with molten resin is provided on one side surface of the mold 1. Two holding pins 2 are installed at predetermined positions on the upper mold 11 and the lower mold 12 so that the holding pins 2 can move forward and backward in the cavity 13. Each holding pin 2 has an air cylinder that moves forward and backward between a position where the insert 5 arranged in the cavity 13 is held at the tip and a position where the tip surface coincides with the mold surface forming the cavity 13 (see FIG. 3).
[0020]
The electric heater 3 constituting the heating means is made of nichrome wire, tungsten wire or the like, and is embedded in each holding pin 2 so as to be insulated from the holding pin body. The electric heater 3 provided on the holding pin 2 of the upper die 11 is connected to one power source 4, and the electric heater 3 provided on the holding pin 2 of the lower die 12 is connected to the other power source 4. Note that it is not necessary to provide two power supplies as in this embodiment, and only one power supply may be used to energize the two holding pins 2.
[0021]
In order to perform insert molding by the molding apparatus of the present embodiment configured as described above, first, each holding pin 2 is projected in a state where the mold 1 is opened, and the insert product is placed on the holding pin 2 of the lower mold 12. Set 5 Next, when the mold 1 is closed, as shown in FIG. 4, the insert product 5 is held at the tip of each holding pin 2 and placed at a predetermined position in the cavity 13.
[0022]
In this state, as shown in FIG. 5, the molten resin 6 is filled into the cavity 13 of the mold 1 through the gate 14 by an injection machine (see FIG. 1). At the same time, when the power supply 4 is switched on, a current is supplied to the electric heater 3 to heat each holding pin 2 to a predetermined temperature. At this time, since the insert product 5 is fixed by the holding pins 2, it does not move due to the flow resistance or pressure of the molten resin 6. Even if the molten resin 6 filled in the cavity 13 comes into contact with the holding pin 2, the holding pin 2 is heated to a temperature equal to or higher than the melting point of the molten resin 6, so that the resin around the holding pin 2 is cooled. A solidified layer is not generated.
[0023]
Next, the air cylinder is driven, and as shown in FIG. 6, the holding pins 2 are retracted to a position where their tip surfaces coincide with the mold surface forming the cavity 13, and then further melted as necessary. Since it is not necessary to heat the holding pin 2 after the resin 6 is filled and the holding pin 2 is retracted, the energization to the electric heater 3 is stopped. As a result, as shown in FIG. 7, the molten resin 6 around each holding pin 2 flows into the pin hole after the holding pin 2 is pulled out and is sufficiently fused, and the pin hole almost disappears and is not fused. No part remains. Thereafter, the molten resin 6 in the cavity 13 is cooled and solidified to form a molded product having high waterproof and oilproof properties in which the insert product 5 is completely sealed with the resin.
[0024]
The timing of retracting each holding pin 2 from the cavity 13 is preferably as early as possible after the molten resin 6 is filled in the entire cavity 13 (after completion of filling), but the range in which the inclination of the insert product 5 is not a problem. In this case, it may be before the molten resin 6 is completely filled in the cavity 13. The filling of the molten resin is completed when the molten resin is filled about 90 to 95% with respect to the volume of the cavity, and then the injection pressure of the molten resin is reduced and further filling is performed. Say.
[0025]
As a timing control method, there are a method in which a timer is used after a predetermined time from the start of filling, a method in which the resin pressure in the cavity 13 is detected by a sensor, the completion of filling is confirmed, and the holding pin 2 is retracted. As described above, according to the insert product molding apparatus of this embodiment, each holding pin 2 heats the holding pin 2 to a temperature equal to or higher than the melting point of the molten resin 6 when the cavity 13 is filled with the molten resin 6. Since the heating means is provided, the insert product 5 can be held by the holding pins 2 until the filling of the molten resin 6 is completed, thereby preventing the insert product 5 from being positioned. In addition, when the holding pin 2 is retracted, a cooling solidified layer of resin is not generated around the holding pin 2, so that an unfused portion caused by the holding pin 2 does not remain, and the insert product 5 is sufficiently sealed. A molded resin product can be formed.
[0026]
Here, with reference to FIG. 8, the remaining unfused portion due to the holding pin 2 will be described in comparison with the conventional example and the present embodiment. In the conventional method, the length of the unfused portion shown in FIG. 8A is long, and the thickness of the resin-molded resin 60 becomes thin where the unfused portion 61 remains, resulting in low reliability. Become. As for a bad thing, the unfused part 61 may penetrate.
[0027]
As shown in FIG. 8 (b), the pin hole 20 formed after the holding pin is retracted is embedded by the surrounding resin pressure as shown in FIG. 8 (c) when FIG. 8 (a) is viewed in the direction of the arrow. However, when the holding pin is not heated as in the conventional product, the unfused portion 61 remains largely as shown in FIG. 8D, but in the present embodiment product, FIG. As described above, the remaining state of the unfused portion 62 can be reduced. In addition, if the heated holding pin 2 is retracted early or if the heating temperature of the holding pin 2 is sufficiently high, the occurrence of an unfused portion can be suppressed.
[0028]
In the above embodiment, as a method of holding the insert 5, it is positioned on the plane of the tip of the holding pin 2, and the receding surface of the holding pin 2 coincides with the mold surface, but as shown in FIG. In addition, there is a method of positioning the insert product 55 reliably by forming a recess in the insert product 55 in advance and making the tip of the holding pin 52 a projection. The irregularities may be square, conical or hemispherical. Further, as shown in FIG. 9, when the mold opening direction and the operation direction of the holding pin 52 are not parallel, the position where the holding pin 52 is retracted is determined by the product being undercut (the holding pin 52 is retracted from the mold surface). Stop in front of the mold surface (see FIG. 10), and the molten resin 57 is solidified so that the molten resin that has entered the retracted portion of the holding pin 52 does not form a protruding portion. Simultaneously with the opening, the holding pin 52 is further retracted (see FIG. 11), and this can be dealt with by a mechanism that does not cause a problem in product removal.
[0029]
In the above embodiment, the holding pin 2 is heated at the same time as the injection of the molten resin is started, and the heating is stopped after the holding pin 2 is retracted. However, the heat generated by the holding pin 2 is generated by the mold 1. If the mold 1 is large and difficult to store heat, or if the number of the holding pins 2 is small and the total amount of heat generated from the holding pins 2 is small, the holding pin 2 is always used. It may be heated.
[0030]
Further, when the insert 5 is a material having low heat resistance such as resin, there is a risk of deformation due to heat and load of the holding pin 2. In this case, instead of heating the holding pin 2 immediately after the mold 1 is closed, a method of rapidly heating the holding pin 2 immediately before (or immediately after) filling the molten resin 6 is employed. Therefore, it is preferable to shorten the time during which the high-temperature holding pin 2 is in contact with the insert product 5. In this case, in order to increase the heating speed of the holding pin 2, it is necessary to install the electric heater 3 in the holding pin 2, particularly in a portion protruding into the cavity 13, and to increase the current density of the electric heater 3. As this method, there is a method in which the ceramic heater is finished in the shape of the holding pin 2 and used without being covered with metal or the like.
[0031]
In order to investigate suitable electric heaters used for the holding pins 2, as shown in Table 1, four types of A to D constituted by variously changing the combinations of the holding pin main body and the heating element of the electric heater are shown. A holding pin was prepared, and each condition item shown in Table 1 was evaluated. Each condition item here is appropriately set based on the molding process model diagram of FIG. 12 showing the relationship between the passage of time in the molding process and the temperature change of the holding pin. In addition, the heating temperature suitable range of a holding pin becomes a part enclosed with the oblique line in FIG.
[0032]
In FIG. 12, it is desirable that the lower limit of the temperature of the holding pin rises to the melting point of the resin at which the resin cooled and solidified around the holding pin is melted again at the timing of removing the holding pin. Further, since the mold temperature is set to a temperature for solidifying the injected molten resin, it is not necessary to adjust the holding pin below the mold temperature. In addition, the upper limit of the temperature of the holding pin is to prevent the insert product from being deformed by the holding pin until molding is started and molten resin is injected into the cavity (molding start timing in the figure). It is desirable to keep it below the heat distortion temperature of resin or the like, and it is important to keep it below the heat deterioration temperature of the resin at the timing when the holding pin is pulled out after the start of molding. The heat deterioration temperature means a temperature at which the physical properties of the material change due to a change in chemical structure caused by heating during or after molding. Further, it is desirable to adjust the temperature to a temperature at which the cooled and solidified resin is not deformed until the molding is finished (timing before resin injection is completed and the mold is opened). This is because if the temperature of the holding pin is not sufficiently lowered at the end of molding, the resin touching the tip of the holding pin stretches in a thread shape when the molded product is taken out, resulting in poor appearance and reduced dimensional accuracy of the molded product. This is to suppress problems such as.
[0033]
From the viewpoint of not wanting to hold an insert product with low heat resistance for a long time with a heated holding pin, an evaluation item considered particularly important from FIG. In addition, when the molding cycle is taken into consideration, it is desired that the temperature lowering rate is fast. Further, as an evaluation item other than those shown in FIG. 12, for example, since the heating method of the holding pin is energization heating, there is a demand for suppressing power consumption as much as possible. In addition, the strength that can withstand the resin pressure of the injected resin and the repeated ON / OFF of the heater can be repeated. Regarding these, four types of holding pins were examined and summarized in Table 1. The holding pin that was tested this time will be described with reference to FIG.
[0034]
In the test pin A shown in Table 1, the holding pin body is made of stainless steel (JIS standard SUS304) and the heating element is also made of stainless steel. As shown in FIG. It is thinned and is itself a heating element. In the main body, a plus-side wire is connected to the tip of the holding pin and a minus-side wire is connected to the other end. Further, the plus side wiring (nichrome wire, tungsten (W) wire) is covered with an insulating member 22 such as silicon gel so as not to be short-circuited to the holding pin body inside the holding pin.
[0035]
As shown in FIG. 13 (b), the test pin B shown in Table 1 is a metal (high-speed steel, high-speed steel JIS standard SKH51 [used for this test], in which the holding pin body 23 is used for a normal holding pin, Die steel JIS standard SKD11 etc.), and W wire was used for the heating element 24. Like the test pin A, the W line is covered with an insulating material 25. As shown in FIG. 13 (d), the first test pin D has MoSi, which is a kind of conductive ceramics, on the heating element 26. ₂ Si, which is a kind of insulating ceramics, is used for the holding pin body 27. _Three N _Four Was used.
[0036]
Moreover, the test pin C shown in Table 1 is shown in FIG. 13C, and a metal cap 28 is further attached to the test pin D shown in FIG. Table 1 summarizes the test results obtained by examining the temperature rise rate, power consumption, strength, and repetition reliability under the temperature conditions shown in FIG. The temperature increase rate was measured by attaching a thermistor as a temperature detector near the tip of the test pin. The power consumption is a measurement of the power consumed in several molding cycles. Further, the strength is represented by the diameter of the holding pin necessary for the strength considered by the inventors. The repeated reliability is determined by checking whether or not the test pin is normal after several tests.
[0037]
When Table 1 is seen, it turns out that the test pins C and D which used ceramics for the heat generating body are good in all the items of temperature rising rate, power consumption, and repetition reliability. Further, it can be seen that the test pin D in which the holding pin main body 23 is also made of ceramic has a higher temperature rising rate than the test pin C. The test pin C is obtained by covering the test pin D with a metal cap 28. This was prepared to compare the differences in strength, but the strength test results were the same for both test pins C and D. In consideration of the temperature increase rate, it can be said that the test pin D without the metal cap 28 is generally better.
[0038]
In addition, since the holding pin main body 21 is a heating element for the test pin A, it is necessary to reduce the wall thickness in order to improve the heat generation, thereby reducing the strength. Further, since the resistance value is small, a large current is required, and the power consumption is considerably increased as compared with other test pins. Further, in terms of repeated reliability, the plus side wiring is brazed to the tip of the pin, and the periphery of the wiring is covered with an insulating material. As a result, the brazed portion could be removed due to the difference in thermal expansion from that of the test pin C, and the reliability was lower than that of the test pins C and D.
[0039]
For the test pin B, the heating rate and power consumption were slightly inferior to those of the test pins C and D, but were not inferior in terms of strength and reliability. The comprehensive evaluation in Table 1 is evaluated from the viewpoint of whether or not it can actually be used. Therefore, the test pin A, which is inferior to the other test pins in the evaluation items, was “good” in that it can be used as a holding pin for heating. That is, regarding the temperature change of the holding pin, the temperature range as shown in FIG. 12 could be satisfied, so that it could be determined that it could be used without considering other conditions.
[0040]
In summary, the test pin A was inferior in all items compared to the other test pins. However, although it is inferior, it does not mean that it cannot actually be used, but it means that there are items that can be used but are inferior in many ways compared to other pins. It became the result.
[0041]
Further, it was found that the test pins B, C, and D can be used satisfactorily. In particular, the test pin D was very good in terms of the rate of temperature rise, and it was possible to give ◎ in the overall evaluation. The reason why the test pin D was heated faster than the other test pins was as follows: (1) heating element, (2) insulating member covering the heating element, and (3) holding pin body This is because the test pin D has a double structure of (1) conductive ceramics and (2) insulating ceramics.
[0042]
The holding pin in the present invention is not limited to the holding pin subjected to the above test. For example, in the case where the holding pin main body 21 and the heating element such as the test pin A are the same, the tested stainless material is used. Not limited to this, other metals may be used. Further, the heating element 24 in the test pin B is not limited to tungsten, and may be anything as long as it is used as a heating element such as platinum (Pt). Further, the holding pin main body 23 is not limited to high-speed steel, and for example, a heating element may be inserted into stainless steel used for the test pin.
[0043]
The conductive ceramic used for the test pins C and D is MoSi. ₂ For example, ZrO ₂ -Y ₂ O _Three , LaF _Three Etc. Other insulating ceramics that can be used as the main body of the holding pin include Al. ₂ O _Three , BeO, MgO and the like. In addition, the ceramic as used in the field of this invention means the inorganic nonmetallic material obtained by heat processing.
[0044]
The holding pin body may be an insulating ceramic, and the heating element may be a metal heating element such as W or Pt. In addition, if the insulation with the holding pin body is performed on the mold side, it is conceivable to form the holding pin only with conductive ceramics. FIG. 14 shows a more specific structure of the holding pin having the same structure as that of the test pin D. FIG. 14A shows the appearance of the holding pin, and FIG. 14B shows a perspective view of the holding pin. As shown in FIG. 14A, the holding pin has a tip portion made of a ceramic heater portion 31, and the ceramic heater portion 31 is held by a metal sleeve 32 at the other end portion. The other end of the ceramic heater portion 32 protrudes from the metal sleeve 32 and is covered with a metal cap 33, and a plus-side electric wire 34 is connected to a part of the metal cap 33. The electric wire 34 includes a metal conductor portion 34a such as copper or enamel and an insulating coating 34b covering the metal conductor portion 34a. The conductor portion 34a is partially exposed and brazed to the metal cap 33. Further, the negative electric wire 35 is brazed to the metal sleeve 32. In addition, the cap 33 portion to which the plus-side electric wire 34 is connected is covered with an insulating coating 33a in order to prevent a short circuit with the minus-side electric wire 35. In this holding pin, a portion that is made thinner than the portion held by the metal sleeve 32 of the ceramic heater portion 31 protrudes into the cavity of the mold.
[0045]
14B, the insulating ceramic 31a covers the conductive ceramic 31b, and the plus side wiring 34c of the conductive ceramic 31b is connected to the metal cap 33. The wire 35c on the minus side is connected to the metal sleeve 32 at the position B in the drawing. FIG. 14C is a cross-sectional view of the holding pin shown in FIG.
[0046]
The shape of the holding pin shown in FIG. 14 is an example, and the present invention is not limited to this.
[0047]
[Table 1]

[0048]
In the above embodiment, the heating of the holding pin 2 is stopped after the holding pin 2 is retracted. However, the molten resin 6 may enter and solidify into the clearance between the holding pin 2 and the mold 1 and the subsequent operation of the holding pin 2 may be disabled. In this case, by performing heating again during the operation of the holding pin 2, the resin in the clearance between the holding pin 2 and the mold 1 can be remelted, and the operation of the holding pin 2 can be restored.
[0049]
In the above description, as a heating method of the holding pin, the heating pin is provided with a heating element and the holding pin is directly heated. However, the heating method of the holding pin is not limited to this. For example, the holding pin may be indirectly heated by providing a heater portion using electricity or the like around the mounting pin of the mold. However, in this case, there is a problem that the holding pin cannot be sufficiently heated because the heating element is separated from the holding pin as compared with the case where the holding pin is directly heated by the electric heater described above.
[0050]
Also, rather than directly heating the holding pin itself with an electric heater, for example, the holding pin main body is in a hollow state like the test pin B, and water that has been brought to a high temperature state by applying pressure or temperature therein, It is also conceivable to heat the holding pin by supplying a medium such as air or oil to the cavity of the holding pin. However, in this case, the temperature rise cannot be expected much because of the characteristics of the medium as compared with the case where the holding pin is heated by the electric heater. Further, since it is necessary to increase the pressure of the medium in order to raise the temperature of the medium, the holding pin is also required to be able to withstand that pressure.
[0051]
In the above description, no mention was made of the temperature drop after raising the temperature of the holding pin, but the temperature may be lowered naturally, or in order to speed up the molding cycle, A temperature lowering means may be provided. As the temperature lowering means, for example, a cooling path such as the flow path 83 of the temperature supply medium 82 for setting the mold temperature as shown in FIG. It is conceivable to forcibly cool the heated holding pin by flowing a cooling medium such as.
[0052]
Further, the temperature after heating the holding pin is desirably the melting point temperature of the resin as shown in FIG. However, the temperature of the holding pin is not necessarily higher than the melting point of the resin. It should be at least higher than the mold temperature. That is, as explained in FIG. 8, conventionally, nothing has been applied to the holding pin itself with respect to the temperature, and the temperature is at most the same as that of the mold at most. Since the temperature of the mold is adjusted to a temperature at which the injected molten resin can be introduced into the cavity and the injected molten resin is hardened, the molten resin is also cooled by the holding pins. When resin molding of the insert product is performed in this state, since the molten resin is cooled and solidified by the holding pin, when the holding pin is retracted, the pin hole is sufficiently embedded by the resin that is cooled and solidified around the holding pin. It was not possible, and the unfused part remained.
[0053]
In other words, the pin hole was not sufficiently embedded because the resin around the holding pin was cooled and hardened by the holding pin. If the hardened resin could be softened, as shown in FIG. Compared to the conventional case, the remaining unfused portion can be suppressed, and the reliability can be improved. Therefore, it is not always necessary to raise the temperature of the holding pin above the melting point of the resin. It is considered that a sufficient effect can be obtained by heating to the deformation temperature of the resin as shown in FIG.
[0054]
For example, when the injection resin is PBT (polybutylene terephthalate) which is a thermoplastic resin, the melting point of PBT is 230 ° C., the thermal deformation temperature of PBT is 150 ° C., and the mold temperature is 70 ° C. to 80 ° C. It is set to about ℃. Accordingly, the heating temperature of the holding pin is heated to 100 ° C., so that the resin around the holding pin is softer than when the holding pin is not heated, and the resin is not pinned as shown in FIG. It is considered that the remaining unfused portion can be suppressed as compared with the case where the holding pin is not heated. In addition, if the holding pin is heated to 150 ° C., which is the thermal deformation temperature of the PBT, the resin around the holding pin is in a sufficiently deformable state, so that the remaining of the unfused portion due to the pin can be sufficiently suppressed. Think of things. If the temperature of the holding pin is heated above the melting point of the PBT, the resin around the holding pin can be melted by the holding pin even if it is cooled and solidified. Therefore, the pin hole after the holding pin is retracted It is possible to almost eliminate the remaining unfused portion due to.
[0055]
[Embodiment 2]
FIG. 15 is a cross-sectional view of the main part of the insert product molding apparatus according to this embodiment.
[0056]
As shown in FIG. 15, the molding apparatus according to the present embodiment includes a mold 101 including an upper mold 111 and a lower mold 112 and having a thin-wall forming portion 115, and a heating unit, and is provided in the mold 101 so as to be movable forward and backward. And two holding pins 102. In addition, the thin-wall formation part 115 in this embodiment is a protruding part as defined in claims 15 and 18. The mold 101 has a cavity 113 corresponding to the outer peripheral shape of a molded product formed by the surfaces of the closed upper mold 111 and lower mold 112 facing each other. A gate 114 is provided on one side of the mold 101 to fill the cavity 113 with molten resin. The mold surfaces of the upper mold 111 and the lower mold 112 are provided with thin-wall forming portions 115 that protrude opposite to the upper and lower mold surfaces at positions corresponding to both end portions of the insert product 105 disposed in the cavity 113. ing. The thin-wall forming portion 115 is set so that the front end face thereof is close to and opposed to the surface of the insert product 105, and the dimension therebetween is about 1 mm. On the other hand, the dimension between the mold surface of the portion other than the thin-wall forming portion 115 (around the holding pin 102) and the surface of the insert product 105 is set to be about 4 mm. Thereby, the thickness of the molten resin filled between the thin-wall forming portion 115 and the insert product 105 is set to be thinner than other portions by the amount of protrusion (about 3 mm) of the thin-wall forming portion 115. Yes.
[0057]
The holding pins 102 are installed one by one in a state where the holding pins 102 are vertically inserted in the central portions of the upper mold 111 and the lower mold 112, and are installed so as to be movable forward and backward in the cavity 113. Each holding pin 102 is provided with an air cylinder (see FIG. 5) that moves forward and backward between a position where the insert 105 arranged in the cavity 113 is held at the tip and a position where the tip face coincides with the mold surface forming the cavity 113. Not shown). The holding pin 102 is made of an insulating ceramic, and an electric heater 121 made of a ceramic heating element is embedded therein. Each electric heater 121 is connected to a power source 103.
[0058]
In order to perform insert molding by the molding apparatus of the present embodiment configured as described above, first, each holding pin 102 is protruded with the mold 101 opened, and the insert product is placed on the holding pin 102 of the lower mold 112. 105 is set. Next, when the mold 101 is closed, as shown in FIG. 15, the insert product 105 is held at the tip of each holding pin 102 and is arranged at a predetermined position in the cavity 113.
[0059]
In this state, as shown in FIG. 16, the molten resin 106 is filled into the cavity 113 of the mold 101 through the gate 114 by an injection molding machine (not shown). At the same time, when the power supply 104 is switched on, a current is supplied to the electric heater 103 to heat each holding pin 102 to a temperature equal to or higher than the melting point of the molten resin. At this time, since the insert product 105 is fixed by the holding pin 102, it does not move due to the flow resistance or pressure of the molten resin 106. Then, after a certain period of time, as shown in FIG. 17, the molten resin 106 gradually cools and solidifies from the contact surface with the mold 101 and the contact surface with the insert product 105, and fills the thin-wall forming portion 115. Since the molten resin 106 has a small thickness, solidification proceeds to the thickness center in a short time, but the thickness center portion of the molten resin 106 filled in other portions remains in a molten state. Even if the molten resin 106 filled in the cavity 113 comes into contact with the holding pin 102, the holding pin 102 is heated to a temperature equal to or higher than the melting point of the molten resin 106. A cooled solidified layer does not form.
[0060]
Then, after the filling of the molten resin 106 is completed, the air cylinder is driven to retract the holding pins 102 to a position where their front end surfaces coincide with the mold surface forming the cavity 113, and further if necessary. Since it is not necessary to heat the holding pin 102 after the molten resin 106 is filled and the holding pin 102 is retracted, the energization to the electric heater 103 is stopped. As a result, as shown in FIG. 18, the surrounding molten resin 106 flows into each pin hole after the holding pin 102 is removed, and the unfused portion caused by the holding pin 102 is sealed without remaining. . At this time, since the insert product 105 is fixed by the resin already solidified in the thin-wall forming portion 115, the insert product 105 is not displaced. Thereafter, the entire molten resin 106 filled in the cavity 113 is cooled and solidified to form a highly waterproof molded product in which the insert product 105 is sufficiently sealed with the resin.
[0061]
As described above, according to the insert product molding apparatus of this embodiment, the mold 101 of this embodiment is opposed to the surface of the insert product 105 disposed in the cavity 113 in the vicinity, and the gap is filled. Since the thin resin forming portion 115 for reducing the thickness of the molten resin 106 is provided, when the holding pin 102 is retracted, the insert product 105 is fixed by the resin that has already been cooled and solidified at the thin portion forming portion 115. Therefore, the positioning of the insert product 105 can be prevented.
[0062]
In addition, since the holding pin 102 includes a heating means for heating the holding pin 102 to a temperature equal to or higher than the melting point of the molten resin 106 when the cavity 113 is filled with the molten resin 106, the filling of the molten resin 106 is completed. Until then, the insert product 105 can be held by the holding pin 102 to prevent the insert product 105 from being positioned, and when the holding pin 102 is retracted, a cooling solidified layer of resin does not form around the holding pin 102. Therefore, an unfused portion caused by the holding pin 102 does not remain, and a resin molded product in which the insert product 105 is sufficiently sealed can be formed.
[0063]
In the above embodiment, the insert product 105 is resin-molded by using both the thin-wall forming portion 115 and the holding pin 102 to be heated. However, the holding pin 102 is also heated only by the thin-wall forming portion 115 without heating the holding pin 102. It is possible to suppress the remaining of the unfused portion due to the pin hole when the is retracted. This will be described with reference to FIG.
[0064]
FIG. 19 shows the inclination of the insert product 105 in the cavity 113 when the holding pin 102 is retracted during molding and the length of the unfused portion due to the pin hole when the holding pin 102 is retracted (FIG. 19). 8), and the inclination of the insert 105 is a ₀ , A ₁ And the length of the unfused part is b ₀ , B ₁ It shows with. In addition, in the inclination of the insert product 105, a ₀ Indicates the inclination in the conventional case without the thin-wall forming portion 115 as in this embodiment, and a ₁ Indicates the inclination when the thin-wall forming portion 115 is used as in this embodiment.
[0065]
In addition, in the length of the unfused part, b ₀ Indicates the length of the unfused portion remaining when the holding pin 102 is retracted without heating the holding pin 102, and b ₁ Shows the length of the unfused portion remaining when the holding pin 102 is heated and retracted as in the first embodiment. In FIG. 19, a ₀ , A ₁ As can be seen, the inclination of the insert 105 is large when the holding pin 102 is retracted immediately after the resin injection is started, and the inclination is sharply small immediately before the resin injection is completed. Become. This is because the insert product 105 is positioned by filling the resin.
[0066]
B ₀ , B ₁ As can be seen, the length of the unfused portion becomes longer as the timing of retracting the holding pin 102 is delayed as the resin injection proceeds. This is because the injected resin is solidified around the holding pins 102 when the timing of retracting the holding pins 102 is delayed. Here, it is assumed that the inclination limit and the length limit of the unfused portion are determined as product specifications as shown in FIG.
[0067]
Even when the thin-wall forming portion 115 is not used as in the prior art, or when the holding pin 102 is not heated, the inclination a ₀ Is A ₀ It is necessary to move the holding pin backward after the timing of the above, and the length b of the unfused portion ₀ Is B ₀ It is necessary to retract the holding pin 102 before this timing, and as can be seen from the figure, there is no timing to retract the holding pin 102 that satisfies both.
[0068]
Therefore, by using the thin-wall forming portion 115 as in the present embodiment, the inclination state of the insert product 105 is changed to the conventional a. ₀ To a ₁ Will shift to A, earlier A ₁ At this timing, the holding pin 102 can be retracted, whereby a product satisfying both the inclination of the insert product 105 and the length of the unfused portion can be manufactured.
[0069]
That is, as can be seen from FIG. 19, by molding the insert product 105 using the thin-wall forming portion 115, the timing for retracting the holding pin 102 with respect to the inclination of the insert product 105 can be accelerated. Early timing (A ₀ By retracting at an earlier timing, the length of the unfused portion can be shortened.
[0070]
Therefore, by using the thin-wall forming portion 115, it is possible to suppress the remaining unfused portion due to the holding pin 102. However, the thin-wall forming portion 115 needs to be provided in a region other than the holding pin 102. In other words, the thickness of the resin around the holding pin 102 remains the same as before, and a thin-wall formation region is provided in a region other than the periphery of the holding pin 102, and the resin solidification around the holding pin 102 remains the same as before. Thus, the resin is allowed to solidify faster in the thin-walled formation region.
[0071]
Furthermore, the length of the unfused portion is shortened by heating the holding pin 102 and moving it backward, as compared with the case where the holding pin 102 is moved back without heating, even if the timing of moving the holding pin 102 back is delayed. be able to. That is, in FIG. ₀ B ₁ Even if the holding pin 102 is retracted at a later timing, the length of the unfused portion can be shortened. Therefore, since the holding pin 102 can be retracted later, the inclination of the insert product 105 can be prevented.
[0072]
Summarizing the above, (1) by providing the thin-walled formation region, the holding pin 102 can be moved back at an earlier timing, whereby the unfused portion remaining due to the pin hole after the holding pin 102 has moved back Can be suppressed. In FIG. 19, A ₁ To B ₀ At this time, the holding pin 102 can be retracted.
[0073]
(2) By heating the holding pin 102, even if the holding pin 102 is retracted at a later timing in order to prevent the insert product 105 from tilting, it is possible to suppress the remaining unfused portion due to the pin hole. In FIG. 19, A ₀ To B ₁ The holding pin 102 can be retracted at this time.
[0074]
(3) Since the effect of the above (1) and (2) can be obtained at the same time by providing the thin-wall formation region and heating the holding pin 102, the tilt of the insert product is sufficiently suppressed, and it is caused by the pin hole of the holding pin. It is possible to suppress the remaining unfused portion. In FIG. 19, A ₁ To B ₁ At this time, the holding pin 102 can be retracted.
[0075]
Note that the dimension between the thin-wall forming portion 115 of the mold 101 and the surface of the insert product 105 becomes smaller, and the thickness of the molten resin 106 filled therebetween becomes thinner and cooling solidification is accelerated. Although the capability is increased, if it is too small, filling failure of the molten resin 106 occurs, so it is preferable to set it to about 0.5 to 1.5 mm. On the other hand, as the dimension between the mold surface of the portion other than the thin-wall forming portion 115 and the surface of the insert product 105 is increased, the pin hole is completely sealed, but the molding cycle becomes longer. It is good to set to about 6 mm.
[0076]
Moreover, in the said embodiment, although the thin formation part 115 of the metal mold | die 101 protrudes from a mold surface, it is trying to make the dimension between the thin formation part 115 and the surface of the insert product 105 small, On the contrary, it is also possible to reduce the dimension between them by using a convex portion formed on the insert product 105 side or by providing a convex portion on the insert product 105. In this case, it may not be necessary to provide the thin-wall forming portion 115 protruding from the mold surface.
[0077]
This is shown in FIG. As shown in this figure, the insert product 105 is provided with an insert-side thin-wall formation region 105 a that is thinner than the thickness of the molding resin around the holding pin 102. In this case, a thin forming region may be provided on the mold. Further, the position and the number of the thin-wall forming portions 115 can be selected and set as appropriate in consideration of the shape and size of the insert product 105.
[0078]
As shown in FIG. 21, various shapes of the thin-wall forming portion 125 are conceivable. 21A shows a trapezoidal shape, FIGS. 21B and 21B have a kamaboko shape, and FIGS. 21C and 21C have a hemispherical shape. The pin hole after the holding pin 102 is retracted is to close the pin hole by softening or melting the resin cooled and solidified around the holding pin 102 with the holding pin. Since the pressure also acts, if the thin-wall forming portion 115 is in front of the holding pin 102 in the direction in which the resin is injected, the resin pressure is not sufficiently transmitted to the pin hole in which the holding pin 102 is retracted. In order to avoid this, it is desirable to shift the positions of the holding pin and the thin-wall forming portion with respect to the resin injection direction.
[0079]
If it demonstrates using FIG. 22, in FIG. 22 (a)-(c), resin shall be inject | poured from the front side of a paper surface to the back side with respect to a paper surface. In FIG. 22A, since the thin-wall forming portion 135 is located in front of the holding pin 132 with respect to the resin injection direction, the resin pressure is not easily transmitted to the pin hole, which is not preferable. As shown in FIGS. 22B and 22C, the positions of the thin-wall forming portion 135 and the holding pin 132 may be shifted with respect to the resin injection direction.
[0080]
In addition, as shown in FIG. 23A, the thin-wall forming portion 145 may be arranged behind the holding pin 142 in the resin injection direction. FIG. 23 (b) shows a cross-sectional view in the direction of the arrow in FIG. 23 (a), and the thin-wall forming portion 145 protrudes into the cavity 143 so as to make one turn with respect to the insert product 140. It is what. Of course, a thin-wall forming portion that replaces the thin-wall forming portion 145 may be provided on the insert product 140 side.
[0081]
As one of the magnetic detection devices using a semiconductor IC, there is a hybrid IC in which a semiconductor IC, a capacitor and the like are mounted on a ceramic substrate. It is conceivable to perform insert molding using the molding apparatus of 1 and Embodiment 2 and to seal the surface with resin. However, when the hybrid IC is used as an insert product and integral resin molding is performed, the resin molding pressure is high (usually 20 to 80 MPa), and therefore there is a problem that cracks occur in the ceramic substrate due to stress.
[0082]
Therefore, by primary molding with a molding material (such as a highly fluid epoxy material) including a sensor element disposed at one end of the ceramic substrate at a resin molding pressure (6 to 8 MPa) that does not cause cracks in the ceramic substrate. When the formed mold IC is used as an insert product, insert molding can be performed by the molding apparatus according to the first and second embodiments without causing cracks in the ceramic substrate.
[0083]
For example, as shown in FIGS. 24 and 25, the magnetic detection device thus manufactured has a plate-shaped mold IC 152 in which the sensor element 151 is embedded on one end side, and a through hole in which the mold IC 152 is fitted. It has a cylindrical hollow magnet 153 and a molded resin portion 154 that seals the hollow magnet 153 and the mold IC 152, and has excellent waterproof and oilproof properties.
[0084]
[Embodiment 3]
FIG. 26 is a cross-sectional view of the insert product forming apparatus according to the present embodiment. FIGS. 27A and 27B are explanatory views showing the assembled state of the insert product used in the present embodiment. FIG. It is a block diagram of the magnetic detection apparatus produced with the insert product shaping | molding apparatus of a form.
[0085]
As shown in FIG. 27 (b), the molding apparatus of the present embodiment is an integral unit comprising a cylindrical hollow magnet 251 having a through hole and a detection device 252 press-fitted into the through hole of the hollow magnet 251. A magnetic detection device in which the insert product 205 is sealed with resin is produced by insert molding using the product as the insert product 205. As shown in FIG. 27A, this insert product 205 is press-fitted until the datum A of the detection device 252 matches the datum B of the hollow magnet 251 so that the output characteristic of the detection device 152 is the best (hollow magnet). In this structure, the distance (e) from the magnetized surface 251 to the tip surface of the detection device 252 is determined.
[0086]
As shown in FIG. 26, the molding apparatus of this embodiment includes a mold 201 composed of a fixed mold 211 and a movable mold 212 configured to be openable and closable in the left-right direction, and a heating means. The main elements are the four holding pins 202 provided on the front and the two supporting pins 207 provided with heating means and provided on the mold 201 so as to be movable back and forth.
[0087]
The mold 201 has a cavity 213 corresponding to the outer peripheral shape of a molded product formed by a surface where the closed fixed mold 211 and the movable mold 212 face each other. Further, gates 214 for filling the cavity 213 with a molten resin (not shown) are provided at both upper ends of the mold 201. Two holding pins 202 are installed on each of the fixed mold 211 and the movable mold 212 in a state where the holding pins 202 are fitted in the lateral direction at the center of the side surface of the mold 201, and can be moved forward and backward in the cavity 213. Is provided. Each holding pin 202 has a space between a position at which the side surface of the hollow magnet 251 of the insert product 205 disposed in the cavity 213 is held at the tip and a position at which the tip substantially coincides with the mold surface forming the cavity 213. An air cylinder (not shown) is provided for driving the cylinder forward and backward. The holding pin 202 is formed of an insulating ceramic in a cylindrical shape, and an electric heater 203 made of a ceramic heating element is embedded therein. Each electric heater 203 is connected to a power source 204 installed on each of the fixed mold 211 side and the movable mold 212 side.
[0088]
One support pin 207 is installed in each of the fixed die 211 and the movable die 212 in a state where the support pin 207 is vertically inserted in a substantially central portion of the lower surface of the die 201, and can be moved forward and backward in the cavity 213. Is provided. Each support pin 207 has a position at which the hollow magnet 251 of the insert product 205 and the lower end surface of the detection device 252 disposed in the cavity 213 are simultaneously supported by the front end surface thereof, and a front end portion on the mold surface forming the cavity 213. There is provided an air cylinder (not shown) that is driven back and forth between the substantially coincident positions. The support pins 207 are formed of an insulating ceramic in a cylindrical shape, and an electric heater 208 made of a ceramic heating element is embedded therein. Each electric heater 208 is connected to a power source 209.
[0089]
In order to perform insert molding by the molding apparatus of the present embodiment configured as described above, first, a pin provided with the hollow magnet 251 of the insert product 205 by the holding pins 202 respectively protruding from the left and right directions in the cavity 213. Insert and fix in the receiving recess. Next, the hollow magnet 251 of the insert product 205 and the lower end surface of the detection device 252 are simultaneously supported by the tip surfaces of the two support pins 207 projecting into the cavity 213 from below. At this time, the vertical direction of the insert product 205 is set so that the distance f between the front end surface of the detection device 252 and the lower end surface of the magnetic detection device becomes the minimum thickness of the mold resin that is confirmed by the durability test and does not generate cracks. Position it.
[0090]
In this state, the cavity 213 of the mold 201 is filled with a high-pressure (20 to 80 MPa) molten resin through a gate 214 by an injection molding machine (not shown). At the same time, when the power supplies 204 and 209 are switched on, current is supplied to the electric heaters 203 and 208 of the holding pins 202 and the support pins 207, and the holding pins 202 and the support pins 207 are heated to a temperature equal to or higher than the melting point of the molten resin. To do. At this time, the hollow magnet 251 of the insert product 205 is held by the four holding pins 202 from the left and right directions, and the lower end surfaces of the hollow magnet 251 and the detection device 252 are filled with the molten resin by the same support pin 207. Since the high injection pressure of the molten resin is applied to the insert product 205 and exceeds the pressure input of the hollow magnet 251 and the detector 252, the hollow magnet 251 and the detector are positioned relative to each other. There is no mess.
[0091]
Even when the molten resin filled in the cavity 213 comes into contact with the holding pin 202, the holding pin 202 is heated to a temperature equal to or higher than the melting point of the molten resin. Does not generate. Next, the air cylinder is driven, and the holding pins 202 and the support pins 207 are retracted to positions where their front end surfaces coincide with the mold surface forming the cavity 213, and thereafter the holding pins 202 and the support pins 207. Therefore, the energization of the electric heaters 203 and 208 is stopped. As a result, the molten resin around the pin holes after the holding pins 202 and the support pins 207 have been removed flows into the pin holes and is completely fused, and the pin holes are completely disappeared and do not remain. Thereafter, the molten resin in the cavity 213 is cooled and solidified, so that the predetermined distance dimensions e and f are secured without positioning the hollow magnet 251 and the detection device 252 as shown in FIG. 29, and the output characteristics are excellent. A magnetic detection device is formed.
[0092]
As described above, according to the molding apparatus of the present embodiment, the support pin 207 that simultaneously supports the hollow magnet 251 of the insert product 205 and the lower end surface of the detection device 252 disposed in the cavity 213 is provided. It is possible to prevent the hollow magnet 251 and the detection device 252 from being positioned by the pressure of the molten resin injected at a high pressure, thereby forming a magnetic detection device with excellent output characteristics.
[0093]
In this embodiment, the hollow magnet 251 of the insert product 205 is fitted to the recess 251a of the hollow magnet 251 as shown in FIG. 27 to hold the insert product 205. By doing so, the position of the insert product can be reliably aligned, so that the position of the insert product inside the molded product when it is formed can be set more reliably, providing a more reliable insert molded product. can do. Furthermore, if the concave portion 251a is tapered so that the holding pin 203 is introduced into the concave portion 251a, the positioning accuracy is further improved.
[0094]
In addition, as shown in FIG. 27, if the tip of the holding pin 202 is sharp, the holding pin 202 pierces the insert product, and the insert product cannot move any more and may not be positioned accurately. Therefore, in order to prevent this, for example, as shown in FIG. 14, it is desirable to flatten the tip while leaving a portion that is tapered to some extent. The tip may be hemispherical.
[0095]
In addition, the above is applicable not only to this embodiment but the said Embodiment 1,2. The insert product in the present invention refers to a component embedded in a resin after molding. For example, there are various types of inserts that are partially exposed on the surface of the molded product, or electrical components such as electric coils, IC components, and thermistors, the surfaces of which are preferably sufficiently sealed with resin. It becomes a target. However, wiring, connectors, and the like for electrical connection with the outside are naturally exposed to the outside of the molded product.
[0096]
In the mold according to the present invention, an insert product is disposed inside and has a cavity corresponding to the outer peripheral shape of the molded product. The cavity in this case means a space portion corresponding to a molded product in a molding die. This mold is composed of an upper mold and a lower mold that can be opened and closed in the vertical direction, or can be opened and closed in the left-right direction in order to place the insert product in the cavity and take out the molded product. Conventional ones such as a fixed type and a movable type can be used. As the mold, a metal mold is usually used.
[0097]
The holding member provided in the mold holds the insert product at a fixed position in the cavity, and is configured to be able to protrude and retract from the mold into the cavity. The operation of the holding member can be performed by a driving device such as a hydraulic cylinder or an air cylinder. As the shape of the holding member, a round bar is generally used, but it is also possible to make it a square bar or an L-shape according to the shape of the insert product. The front end surface of the holding member is a surface that forms a cavity together with the mold surface of the mold when the holding member is retracted from the cavity. As the material of the holding member, a steel material for molds is usually used, but a ceramic material may be used so that it can withstand the heating of the heating means described later.
[0098]
That is, the mold is for cooling and solidifying the injected molten resin, while the holding member heated by the heating means prevents the resin around the holding member from solidifying or melts the solidified resin. It is close to. In the heating means in the present invention, as the degree of heating, the resin around the holding member may be kept in a molten state, and if the temperature is higher than the cavity surface temperature of the mold, the unfused due to the holding member The effect which suppresses the remainder of a part is exhibited. Preferably, it is set to not less than the melting point of the resin and not more than the heat deterioration temperature. As the heating means, an electric heater (for example, a nichrome wire, a tungsten wire, a platinum wire, a conductive ceramic, etc.) that generates heat when supplied with a current from a power source can be used. The installation position of the electric heater is best inside the holding member in order to quickly heat the holding member. However, if there is a space limitation inside the holding member, heat is applied from the outside of the holding member by heat conduction. May be. In general, the power source for the electric heater is preferably a switching power source that can supply a large current at a constant current value. As for the number of power supplies used, if one unit is used for each holding member, the temperature of each holding member may be adjusted. However, when a strict temperature control is not required, a plurality of holding members are used. It may be heated with a power supply of the stand. Note that one holding member or a plurality of holding members may be used.
[0099]
The molding apparatus of the present invention is suitable for performing insert molding using a thermoplastic resin. As a thermoplastic resin, various things, such as PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), a polyamide system, a polyester system, can be used, for example.
[Brief description of the drawings]
FIG. 1 is a front view of an injection molding machine according to a first embodiment.
FIG. 2 is an enlarged perspective view showing a part of the injection molding machine according to the first embodiment.
FIG. 3 is a front view showing a state in which the mold of the injection molding machine according to Embodiment 1 is opened.
FIG. 4 is a cross-sectional view of the insert product forming apparatus according to the first embodiment.
FIG. 5 is a cross-sectional view in the molding process of the insert product molding apparatus according to the first embodiment.
FIG. 6 is a cross-sectional view in a molding process of the insert product molding apparatus according to the first embodiment.
FIG. 7 is a cross-sectional view in the molding process of the insert product molding apparatus according to the first embodiment.
FIG. 8 is an explanatory diagram showing a state in which an unfused portion due to the holding pin remains in the resin molded product.
FIG. 9 is an explanatory view showing a method of holding an insert product by a holding pin.
FIG. 10 is an explanatory view showing a method of holding an insert product with a holding pin.
FIG. 11 is an explanatory view showing a method of holding an insert product by a holding pin.
FIG. 12 is a model diagram showing the relationship between the passage of time in the molding process and the temperature change of the holding pin.
FIGS. 13A, 13B, 13C, and 13D are explanatory views showing the structure of each holding pin used in the test in Embodiment 1. FIGS.
FIGS. 14A, 14B, and 14C are an external view, a perspective view, and a cross-sectional view of a holding pin having a heating unit according to Embodiment 1. FIGS.
FIG. 15 is a cross-sectional view of an insert product molding apparatus according to a second embodiment.
FIG. 16 is a cross-sectional view in the molding process of the insert product molding apparatus according to the second embodiment.
FIG. 17 is a cross-sectional view in the molding process of the insert product molding apparatus according to the second embodiment.
FIG. 18 is a cross-sectional view in the molding process of the insert product molding apparatus according to the second embodiment.
FIG. 19 is an explanatory view showing the relationship between the inclination of the insert product in the cavity and the length of the unfused portion caused by the pin hole when the holding pin is retracted during molding.
FIG. 20 is an explanatory diagram when a thin-wall forming region is provided in the insert product in the second embodiment.
FIGS. 21 (a), (b), (b ′), (c), and (c ′) are explanatory views showing shapes of various thin-wall forming portions provided in the mold in the second embodiment.
FIGS. 22A, 22B, and 22C are explanatory views showing a positional relationship between a thin-wall forming portion provided in a mold and a holding pin in Embodiment 2. FIGS.
FIGS. 23A and 23B are explanatory views showing a positional relationship between a thin-wall forming portion provided in a mold and a holding pin in Embodiment 2. FIGS.
24 is a partial cross-sectional front view of a magnetic detection device that is resin-molded by the insert product molding device according to Embodiments 1 and 2. FIG.
FIG. 25 is a partial cross-sectional plan view of a magnetic detection device that is resin-molded by the insert product molding device according to the first and second embodiments.
FIG. 26 is a cross-sectional view of an insert product molding apparatus according to Embodiment 3.
FIGS. 27A and 27B are explanatory views showing an assembled state of the insert product according to the third embodiment. FIGS.
FIG. 28 is a configuration diagram of a magnetic detection device produced by an insert product molding apparatus according to Embodiment 3.
[Explanation of symbols]
1, 101, 201 ... mold
2, 52, 92, 102, 132, 142, 202 ... holding pins (holding members)
3, 103, 203, 208 ... Electric heater (heating means)
4, 104, 204, 209 ... Power source (heating means)
5, 55, 90, 105, 140, 205 ... inserts
6, 57, 106 ... Molten resin
11, 111 ... upper mold
12, 112 ... Lower mold
13, 76, 91, 113, 213 ... cavity
14, 104, 204 ... Gate
20 ... pin hole
21, 23, 27 ... holding pin body
22 ... Insulating member
24, 26 ... heating element
25. Insulating material
28, 33 ... Metal cap
31 ... Ceramic heater part
32 ... Metal sleeve
34, 35 ... Electric wire
70 ... pedestal
71 ... Hopper
72. Injection machine
73 ... Die mounting board
74 ... Mold opening and closing device
75 ... Spru
77 ... Gate
78 ... Ejector pin
79 ... Heater part
80 ... hole
81. Metal heater
82 ... Temperature supply medium
83 ... Flow path
93 ... Runner part
94. Connection part
95 ... Cylinder
96 ... Connection part wiring hole
97 ... Mold part wiring hole
98 ... wiring
99 ... Power supply
60 ... resin
61, 62 ... Unfused part
72. Injection machine
105a ... Thin-wall formation region
115, 125, 135, 145 ... Thin-wall forming part (protruding part)
115a ... taper portion
207 ... Support pin
211 ... Fixed type
212 ... Movable type

Claims (5)

In a state where the insert is held in the cavity by holding members opposed to each other , the molten resin is injected into the cavity, and before the molten resin is completely filled in the cavity. Alternatively, in the insert molding method in which the holding member is retracted from the cavity after the completion of filling and the insert product is resin-molded, in the resin portion formed by the molten resin filled between the cavity and the insert product, Of the region in which the holding member is not located, a region in which cooling of the molten resin is promoted more than a peripheral region including a region in which the holding member is located is formed opposite to the insert product. Insert molding method.   2. The insert according to claim 1, wherein in the region where the cooling is promoted, the thickness of the resin portion is made thinner than the thickness of the peripheral resin portion where the holding member is located. Product molding method. The insert product includes an outer part having a hollow part and an inner part inserted into the hollow part of the outer part, and one end of the outer part and the inner part is simultaneously supported by one holding member. The insert product molding method according to claim 2 . A mold having a cavity in which the insert product is disposed, and a holding member which is provided so as to be movable forward and backward with respect to the mold and protrudes oppositely into the cavity to hold the insert; In a state of being held by the holding member, molten resin is injected into the cavity, and the holding member is retracted from the cavity before or after the molten resin is filled into the cavity, and the insert product is sealed with resin. In the insert molding apparatus, the opposing surface portion exposed to the cavity of the mold has a cooling promotion surface portion that cools and solidifies the resin faster than a surface portion around the holding member. Insert product molding equipment.   In the cooling promotion surface portion, the thickness of the resin between the cooling promotion surface portion and the insert product is larger than the thickness of the resin between the surface portion around the holding member and the insert product. The insert product forming apparatus according to claim 4, further comprising a raised portion to be thinned.

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