JP2004034443A

JP2004034443A - Injection molding method and injection molding mold

Info

Publication number: JP2004034443A
Application number: JP2002193377A
Authority: JP
Inventors: Ikuo Asai; 浅井　郁夫
Original assignee: Meiki Seisakusho KK
Current assignee: Meiki Seisakusho KK
Priority date: 2002-07-02
Filing date: 2002-07-02
Publication date: 2004-02-05
Anticipated expiration: 2022-07-02
Also published as: JP3719512B2

Abstract

<P>PROBLEM TO BE SOLVED: To mold a plate-shape resin molded product such as a light guide plate free from a sink mark near a corner part. <P>SOLUTION: A cavity C with a stamper 34 having a transfer face 34b formed following the shape of the light guide plate P as a finished product, is formed between the opposite face, to a fixed half 2, of a movable half 4 and the opposite face, to the movable half 4, of the fixed half 2. In the cavity C, cavity forming faces formed in an approximately orthogonal direction with the stamper 34 and a moving means 37 which moves at least one of the cavity forming faces along the stamper 34 in an approximately orthogonal direction with a mold opening/closing direction, are provided. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は固定金型と可動金型の間に平板状に形成されたキャビティ形成面に溶融樹脂を射出充填し、平板状樹脂成形品である導光板等を成形する射出成形方法および射出成形金型に関するものである。
【０００２】
【従来の技術】
従来平板状樹脂成形品である導光板の射出成形は、金型に取付けられたスタンパへの転写を良好にするため、特開２０００−２２９３４３号公報等に示される射出圧縮成形や、特開２０００−２１８６５４号公報等に示される射出プレス成形といった成形方法によって行われている。ところが前記した導光板の成形方法は、キャビティ内に射出された溶融樹脂に対し、成形される導光板の厚さ方向にのみ可動金型を移動させて圧縮を行うため、ゲート部の位置から遠い側の導光板の隅部をはじめ各隅部付近においてヒケ（溶融樹脂の充填不足）が発生する場合があった。特に導光板を成形する場合は、ゲートの痕跡が残るため入光面や出光面にゲート部を設けることができず、入光面の他側にゲート部が形成される場合が多く、前記したヒケが発生する問題の解決が重要であった。また前記公報のように成形される導光板の厚さ方向にのみ可動金型を移動させて圧縮を行うものでは、導光板の厚さが射出充填される溶融樹脂の量や型締シリンダの制御量の微妙な相違によって左右され、導光板の厚さ精度が出しにくいという問題があった。更にまた近年パソコン等の画面の大型化に伴い、導光板自体も大型で肉厚のものが求められているが、大型で肉厚な導光板を成形する際には特に、導光板の冷却に時間がかかるため成形サイクルが遅くなるという問題があった。
【０００３】
【発明の解決しようとする課題】
そこで本発明は、隅部付近にヒケのない導光板等の平板状樹脂成形品を成形することを目的とする。また成形される導光板の転写性を良好にするとともに、成形サイクルを早くすることを目的とする。
【０００４】
【課題を解決するための手段】
請求項１の平板状樹脂成形品の射出成形方法は、可動金型の固定金型対向面と固定金型の可動金型対向面との間に成形品である平板状樹脂成形品の形状に倣って形成されたキャビティが形成され、キャビティに連通するゲート部からキャビティ内に溶融樹脂を射出充填し、型開閉方向に沿って形成され平板状樹脂成形品の側端面を形成するキャビティ形成面の少なくとも一を型開閉方向と略直角方向に移動させ、キャビティ内の溶融樹脂を圧縮することを特徴とする。よって平板状樹脂成形品の隅部付近のヒケをなくすことができる。
【０００５】
請求項２の導光板の射出成形方法は、可動金型の固定金型対向面と固定金型の可動金型対向面との間に成形品である導光板の形状に倣って形成され転写面を有するスタンパが設けられたキャビティが形成され、キャビティに連通するゲート部からキャビティ内に溶融樹脂を射出充填し、型開閉方向に沿って形成され導光板の側端面を形成するキャビティ形成面の少なくとも一をスタンパに沿って型開閉方向と略直角方向に移動させ、キャビティ内の溶融樹脂を圧縮することを特徴とする。よって導光板の隅部付近のヒケをなくすことができる。
【０００６】
請求項３の導光板の射出成形金型は、可動金型の固定金型対向面と固定金型の可動金型対向面との間に成形品である導光板の形状に倣って形成され転写面を有するスタンパが設けられたキャビティが設けられ、キャビティには前記スタンパに対して略直角方向に形成されるキャビティ形成面と、そのキャビティ形成面の少なくとも一をスタンパに沿って型開閉方向と略直角方向に移動させる移動手段を設けたことを特徴とする。よって導光板の隅部付近のヒケをなくすことができる。
【０００７】
請求項４の導光板の射出成形金型は、請求項３において、移動手段によって移動されるキャビティ形成面は、成形される導光板の入光面を形成するキャビティ形成面であることを特徴とする。よって成形される導光板の入光面付近のヒケをなくすことができる。
【０００８】
請求項５の導光板の射出成形金型は、請求項３または請求項４において、ゲート部は、移動手段によって移動されるキャビティ形成面の他側に設けられたことを特徴とする。よってゲート部から遠い側の隅部付近のヒケをなくすことができる。
【０００９】
請求項６の導光板の射出成形金型は、可動金型の固定金型対向面と固定金型の可動金型対向面との間に成形品である導光板の形状に倣って形成され転写面を有するスタンパが取付けられたキャビティが設けられ、スタンパの背面側に高温制御部と低温制御部とが配設された温調部材が、温調部材移動手段によってスタンパの背面部に沿って移動可能に設けられたことを特徴とする。　よって成形される導光板に転写を良好にするとともに、冷却を早く行うことができ、成形サイクルを向上させることができる。
【００１０】
【発明の実施の形態】
本発明の実施の形態について図１ないし図５を参照して説明する。図１は本発明の導光板の射出成形金型の射出充填前の断面図である。図２は図１におけるＡ−Ａ線における断面図である。図３は本発明の導光板の射出成形金型の可動金型を固定金型側から見た図である。図４は本発明の導光板の射出成形金型の冷却時の断面図である。図５は本発明の導光板の射出成形金型における導光板取出時の断面図である。
【００１１】
図１において、本発明の導光板Ｐの射出成形金型は、固定盤１に取付けられる固定金型２と可動盤３に取付けられる可動金型４とからなっており、固定金型２に対して可動金型４を型合せした際に、可動金型４の固定金型対向面と固定金型２の可動金型対向面によって導光板Ｐの形状に倣った平板状のキャビティＣが形成可能に設けられている。導光板Ｐの射出成形金型の固定金型２について先に説明すると、固定金型２は、固定金型２を固定盤１にボルトによって取付ける取付板５、取付板５に固定された本体部６、取付板５の略中央に形成されたスプルブッシュ７、前記スプルブッシュ７に連通し本体部６の内部に形成された溶融樹脂通路８、本体部６の反取付板側に取付られた凸状の鏡面板９、前記溶融樹脂通路８に連通し、鏡面板９に形成されたゲート部１０等から構成されている。そして前記鏡面板９の内部には温調用媒体通路１１が形成され、図示しない温調器から管路１２を経て温調用媒体が送られ鏡面板９の温度が調整可能に形成されている。また鏡面板９の反本体部側の可動金型対向面には、キャビティＣを構成する平面状のキャビティ形成面１３が形成されている。そしてまた前記本体部６の可動金型対向面には、可動金型４と当接する当接面１４が形成されている。
【００１２】
次に可動金型４について説明すると、可動金型４には、可動金型４を可動盤３にボルトによって取付ける取付板１５と、取付板１５に固定された本体部１６が設けられている。図２，図３に示されるように、本体部１６の反取付板側には中央部にキャビティＣの一部が形成される空間を有する枠体部１７が固定されている。そして前記本体部１６と枠体部１７との間には所定の寸法からなる開口を有する連通孔部１８が可動金型４を上下方向に貫通形成されている。そして前記連通孔部１８の中間部付近のキャビティＣ側は後述するスタンパ３４によって閉鎖されている。そして前記連通孔部１８とスタンパ３４によって囲繞された空間には、鏡面からなる温調部材１９が収容されている。よって温調部材１９は、スタンパ３４の背面部３４ａ側に収容されていることになる。
【００１３】
温調部材１９は、ヒーター２３がスタンパ３４側（前面側）に固設された高温制御部２４と、温調用媒体通路２５が内部に形成された低温制御部２６が、断熱部２７を挟んで配設されている。そして高温制御部２４のヒーター２３には図示しない電源から電線２８が接続され、また低温制御部２６には図示しない温調器から管路２９が接続され、それぞれ高温制御部２４と低温制御部２６の温度制御が可能に設けられている。そして高温制御部２４の外側部分、低温制御部２６の外側部分にはそれぞれ延設部３０、３１が配設され、高温制御部２４と前記延設部３０の間には断熱部３２が配設されている。また低温制御部２６と延設部３１との間にも断熱部３３が配設されるとともに、前記延設部３１には可動金型４にブラケット４５によって固設された温調部材移動手段である油圧シリンダ２２のロッド２２ａが固定されている。また図２に示されるように断面視した温調部材１９の両側には爪部２１が設けられ、温調部材１９は、前記連通孔部１８内部における枠体部１７の側に形成されたガイド溝２０に前記爪部２１がガイドされている。そして温調部材１９は、前記油圧シリンダ２２の駆動により前記ガイド溝２０にガイドされ、前記スタンパ３４の背面部３４ａに沿って高温制御部２４と低温制御部２６とが配設される方向に移動可能に設けられている。
【００１４】
そして温調部材１９の爪部２１とガイド溝２０の間を含む温調部材１９の側面側と、枠体部１７の側との間には、所定の間隔が設けられ、温調部材１９の熱膨張に対応可能となっている。また温調部材１９のスタンパ３４側の面とスタンパ３４の背面部３４ａは互いに潤滑面に形成されている。更に温調部材１９と本体部１６についても、温調部材１９の移動を容易にする手段が講じられている。この実施の形態では本体部１６の内部にはエア供給管路４６が形成され、エア供給管路４６は温調部材１９の本体部１６側に開口している。そしてエア供給管路４６は管路４７を介して図示しない圧縮エア供給手段に接続され、前記エア供給手段からエアを圧送することにより、温調部材１９の連通孔部１８内での移動を容易にしている。また上記以外に本体部１６と温調部材１９との間は互いの面を潤滑面とするか、ローラーベアリング等を設けてもよい。
この実施の形態では、温調部材１９はスタンパ３４が取付けられた可動金型４にのみ取付けられているが、成形品の反りを防止する目的から、可動金型４と固定金型２に取付けてもよい。
【００１５】
そして図２に示されるように、前記した枠体部１７には前記ガイド溝２０の固定金型２側に型開閉方向と略直角方向にスタンパ取付面３５が形成され、前記スタンパ取付面３５にはスタンパ３４が取付けられている。スタンパ３４は平板状のニッケル製の０．３ｍｍないし１．５ｍｍの薄板であり、その表面側のキャビティＣを構成する部分は導光板Ｐにパターンを形成させる転写面３４ｂとなっている。なおこの実施の形態では、スタンパ３４は可動金型４の固定金型対向面に取付けられているが、可動金型４の固定金型対向面および／または固定金型２の可動金型対向面に取付けられたものであればよく、温調部材１９もスタンパ３４に対応して固定金型２側にも設けてもよい。
枠体部１７には平板状のスタンパ３４に対応して、４箇所に所定の長さのスタンパ押え部材３６が固定され、スタンパ３４の周辺部３４ｃを押さえている。スタンパ押え部材３６とスタンパ３４の周辺部３４ｃとの間は溶融樹脂が入り込まない僅かな間隔に形成され、またスタンパ押え部材３６によりスタンパ３４の側端部３４ｄには空間が形成され、スタンパ３４の熱膨張に対応可能になっている。
【００１６】
前記枠体部１７には導光板Ｐの側端面を構成するキャビティ形成面３８ａ、３８ｂを型開閉方向と略直角方向に移動させる移動手段である油圧シリンダ３７がそれぞれ設けられている。この実施の形態では油圧シリンダ３７は、枠体部１７に上下４箇所づつ合計８箇所にロッド３７ａをキャビティＣの側に向けて内装されている。しかし移動手段は油圧シリンダ３７に限定されず、サーボモータやリニアモータを用いることにより、更に精度の高いキャビティ形成面３８ａ，３８ｂの移動を行うようにしてもよい。そして前記油圧シリンダ３７のロッド３７ａには、キャビティＣにおいて成形品の側端部を形成するキャビティ形成面３８ａ，３８ｂをロッド３７ａの取付側とは反対側に有するスライドブロック３９ａ，３９ｂが取付けられている。よって前記スライドブロック３９ａ，３９ｂは、スタンパ３４の周辺部３４ｃに沿って型開閉方向と略直角方向に移動され、前記スライドブロック３９ａ，３９ｂのキャビティ形成面３８ａ，３８ｂは、前記スタンパ３４の転写面３４ｂや周辺部３４ｃに対して略直角方向に形成されていることになる。またスライドブロック３９ａ，３９ｂにおけるスタンパ３４側の側面４０と、前記スタンパ３４の周辺部３４ｃとの間は溶融樹脂の入り込まない僅かな間隔を経て対向している。また固定金型２と可動金型４を型合わせした際に、前記スライドブロック３９ａ，３９ｂにおける鏡面板９側の側面４１と、鏡面板９のキャビティ形成面１３とについても溶融樹脂の入り込まない僅かな間隔を経て対向するよう設けられている。
【００１７】
この実施の形態では、図３に示されるように、スタンパ３４と略直角方向に形成されるキャビティ形成面のうち、導光板Ｐの入光面を形成するキャビティ形成面３８ａ，３８ｂが、スライドブロック３９ａ，３９ｂによって構成され、他の左右の２面が移動不可能なキャビティ形成面４２となっている。ただしスライドブロックは、スタンパ３４と略直角方向のキャビティ形成面のうちゲート部１０とは他側のキャビティ形成面のみとしてもよく、少なくとも一面ないし四面全部のいずれかをスライドブロックとしてもよい。また導光板Ｐをパソコン等に取付ける際に必要な導光板側面の凹凸を成形する目的で、キャビティ形成面３８ａおよび／またはキャビティ形成面３８ｂを複数の面に分割し、そのうちの少なくとも一面をスライドブロックとしてもよい。
【００１８】
そしてこの実施の形態では一方のキャビティ形成面３８ａの他側の固定金型２の鏡面板９には、スライドブロック３９ｂの移動によって閉鎖されるゲート部１０が設けられている。また枠体部１７のスタンパ取付面３５については図２に示されるように、図示しない負圧手段に接続されたエア吸引管路４３が形成されており、スタンパ押え部材３６によって押えられたスタンパ３４の背面部３４ａの周端部を吸引可能に設けられている。また枠体部１７の固定金型対向面は当接面４４となっており、型合わせした際、固定金型２の当接面１４と当接する。
【００１９】
次にこの実施の形態における導光板Ｐの射出成形金型による導光板Ｐの成形方法について説明する。この実施の形態における導光板Ｐの射出成形金型によって成形される導光板Ｐは、厚さが均一で両側の側端面に入光面を有し、一方の面にスタンパ３４によって微細なドットや溝からなるパターンが形成されたものであるが、成形される導光板Ｐについては、両面にスタンパ３４によってパターンが形成されたものでもよく、入光面についても２面に限定されない。また導光板Ｐの形状は厚さが均一なものに限定されず、楔型導光板であってもよい。ただし楔型導光板の場合、キャビティＣの断面積が一定である方向にスライドブロックが移動可能なように設ける必要がある。またこの実施の形態ではアクリルにより導光板Ｐを成形するが、ポリカーボネートやシクロオレフィン樹脂等の他の透明樹脂を用いてもよい。
【００２０】
まず導光板Ｐの射出成形金型のキャビティＣに図示しない射出装置から溶融樹脂を射出充填する工程の前に、スライドブロック３９ａ，３９ｂを後退させ、キャビティＣの容積を拡大させておく。また同時に温調部材移動手段である油圧シリンダ２２によって温調部材１９の高温制御部２４がスタンパ３４の背面部３４ａに対応するように移動させ、ヒーター２３に通電を開始し、高温制御部２４を昇温させるか、予め昇温させておく。スタンパ３４が前記高温制御部２４からの伝熱により１５０℃に昇温され、図示しない型締装置により可動金型４が移動されて、可動金型４の当接面４４と固定金型２の当接面１４が当接されるのと前後して、図４に示されるように、油圧シリンダ２２を駆動させ、温調部材１９を移動させる。そしてスタンパ３４の背面部３４ａに当接される温調部材１９の部分は、高温制御部２４から低温制御部２６に切換えられる。なおこの実施の形態では温調部材１９は、スタンパ３４の背面部３４ａとが直接当接しているが、１ｍｍないし５ｍｍの厚さの鉄板等からなる畜熱部材をスタンパ３４の背面部３４ａに取付け、前記鉄板を介して温調部材１９とスタンパ３４を当接させるようにしてもよい。そのようにすることにより低温制御部２６がスタンパ３４に当接してから、射出充填開始時までのスタンパ３４の冷却を遅らせることができる。
温調部材１９が移動され、型締がなされると、図示しない射出装置からスプルブッシュ７、溶融樹脂通路８、ゲート部１０を介して溶融樹脂をキャビティＣ内に射出充填する工程を行う。この実施の形態では、溶融樹脂は２８０℃で、８０ＭＰａの射出圧力で射出充填される。
【００２１】
次に移動手段である油圧シリンダ３７によりスライドブロック３９ａ，３９ｂをスタンパ３４に沿って前進移動させ、射出充填された溶融樹脂を圧縮する工程を行う。なおこの際のスライドブロック３９ａ，３９ｂの移動は、溶融樹脂の射出充填中または射出充填完了後に移動を開始するようにしてもよい。そしてこの実施の形態では、スライドブロック３９ｂが移動されることにより、ゲート部１０が閉鎖される。そして特にゲート部１０が、キャビティＣにおいて、入光面が形成されるスライドブロック３９ａのキャビティ形成面３８ａに対して他側にある場合は、入光面付近のヒケをなくす効果が大きい。またこの実施の形態では、スライドブロック３９ａと３９ｂの移動は同時に行われるが、スライドブロック３９ａと３９ｂの移動のタイミングをずらすようにしてもよい。
【００２２】
そして溶融樹脂の射出充填が完了し、スタンパ３４の転写面３４ｂにより溶融樹脂への転写が完了すると、前記したようにスタンパ３４の背面部３４ａには、図示しない温調器により約５０℃に制御されている温調部材１９の低温制御部２６が当接されているので、低温制御部２６に背面部３４ａが当接されたスタンパ３４は急激に冷却され、冷却されたスタンパ３４を介してキャビティＣ内の溶融樹脂の冷却が促進される。そして溶融樹脂の冷却が完了すると、図５に示されるように、油圧シリンダ３７により、スライドブロック３９ａ，３９ｂが後退され、スライドブロック３９ａ，３９ｂのキャビティ形成面３８ａ，３８ｂと成形された導光板Ｐの側面側との固着が解除される。そして型締装置により型開きが行われると、取出機４８が固定金型２と可動金型４との間に移動され、取出機４８の吸盤４９によって成形された導光板Ｐが吸着され、取出しが行われる。そして次の成形までの間に油圧シリンダ２２が駆動され、温調部材１９のうちの高温制御部２４が再度スタンパ３４の背面部３４ａに移動される。
【００２３】
次に図６に示される別の実施の形態について説明する。
図６に示される別の実施の形態の射出成形金型は、キャビティＣ内に射出充填された溶融樹脂に対して、型開閉方向への圧縮とスタンパの転写面と平行方向への圧縮の両方を行うものであり、射出圧縮成形や射出プレスといった成形方法が行えるものである。図１ないし図５に示される実施の形態との相違点を中心に記載する。図６に示される別の実施の形態では固定金型５１は、本体部５２と本体部５２の可動金型側（前面）に取付けられる鏡面板５３等からなり、そして鏡面板５３の可動金型対向面にはキャビティ形成面である転写面５５ａを有するスタンパ５５が取付けられている。また本体部５２の可動金型対向面には当接面５６が設けられており、鏡面板５３と本体部５２の当接面５６とは略平面形状に形成されている。
【００２４】
また可動金型５４には、本体部５７と本体部５７の前面に取付けられる鏡面板５８とが設けられており、鏡面板５８の固定金型対向面にはキャビティ形成面５９が形成されている。また本体部５７の周囲には枠体部６０が形成され、本体部５７と枠体部６０との間に固着された複数のバネ６１により、枠体部６０は本体部５７に対して型開閉方向の位置が可変に設けられている。また枠体部６０の固定金型対向面には、固定金型５１と当接する当接面６２が形成されている。また本体部５７と枠体部６０との間にはそれぞれ段部６３ａ，６３ｂが形成され、段部６３ａと６３ｂが当接することにより枠体部６０が所定の位置より後退不可能に設けられている。
【００２５】
枠体部６０には複数の油圧シリンダ６４がロッド６４ａをキャビティＣに向けて設けられ、油圧シリンダ６４のロッド６４ａには、スライドブロック６５が固着されている。そして油圧シリンダ６４の駆動によって前記スライドブロック６５がスタンパ５５の転写面５５ａと平行に移動可能に設けられている。スライドブロック６５のロッド６４ａが固定されている面とは反対側には前記スタンパ５５の転写面５５ａとは略直角方向にキャビティ形成面６６が設けられている。そして枠体部６０が最も後退したときに、スライドブロック６５の鏡面板５８側の側面６７と、鏡面板５８のキャビティ形成面５９が溶融樹脂が入らない僅かな間隔となるように設定されている。またスライドブロック６５が設けられていない枠体部６０の内側のスタンパ５５の転写面５５ａと略直角方向に別のキャビティ形成面６９が形成されている。またこの実施の形態ではゲート部６８は可動金型５４側の前記スタンパ５５の転写面５５ａとは略直角方向に形成されたキャビティ形成面６９に形成されている。
【００２６】
次にこの図６に示される別の実施の形態の導光板Ｐの射出成形金型による導光板Ｐの成形方法について記載すると、溶融樹脂をキャビティＣ内に射出充填する前には、油圧シリンダ６４によりスライドブロック６５は後退させておく。図示しない型締装置により可動金型５４を前進させ、可動金型５４の当接面６２と固定金型５１の当接面５６が当接されると型締装置による型締力を一定の圧力に保持する。その際枠体部６０は、前記型締力とバネ６１の付勢力とのバランスにより、固定金型５１と当接していないときの枠体部６０に位置から所定量だけ本体部５７に対して後退した位置となる。次に図示しない射出装置からゲート部６８を介して溶融樹脂がキャビティＣ内に射出充填される。溶融樹脂がキャビティＣ内に射出充填されると、図示しない型締装置による型締力を増圧して、バネ６１を更に収縮させ、キャビティＣ内の溶融樹脂を型開閉方向に圧縮させる。やがて本体部５７の段部６３ａと枠体部６０の段部６３ｂが当接されると型締シリンダによる型締力をその位置を保つように保持する。次に油圧シリンダ６４を前進させ、スライドブロック６５によってキャビティＣ内の溶融樹脂が圧縮される。そして上記によりキャビティＣ内の溶融樹脂は、型開閉方向および型開閉方向と略直角方向の両方から圧縮を受け、導光板Ｐが成形される。なおこの実施の形態の場合、スライドブロック６５による前進ストロークは例えば１ｍｍ程度の僅かなストロークに設定してもよく、スライドブロック６５により、いずれかの面のキャビティ形成面６６の一部のみを圧縮するようにしてもよい。
【００２７】
なお本発明の実施の形態については、一例として導光板Ｐの射出成形について記載したが、他の平板状の樹脂成形品の射出成形に用いることができる。例えば、燃料電池のセパレータや、パソコンの枠体等に成形に用いることができ、成形品に凹凸のあるものや、孔があるものであってもよく、使用される樹脂材料やその他成形条件等も本発明を実施できる範囲内であれば限定されない。
【００２８】
【発明の効果】
本発明の平板状樹脂成形品の射出成形方法および射出成形金型は、可動金型の固定金型対向面と固定金型の可動金型対向面との間に成形品である平板状樹脂成形品の形状に倣って形成されたキャビティが形成し、キャビティに連通するゲート部からキャビティ内に溶融樹脂を射出充填し、型開閉方向に沿って形成され平板状樹脂成形品の側端面を構成するキャビティ形成面の少なくとも一を型開閉方向と略直角方向に移動させて、キャビティ内の溶融樹脂を圧縮することを特徴とする。よって平板状樹脂成形品の隅部のヒケをなくすことができる。そして特にゲート部の他側のキャビティ形成面を移動可能なキャビティ形成面とすることにより、ゲート部から遠い部分のヒケをなくすことができ、導光板においては入光面のヒケをなくすことができる。
【００２９】
また本発明の導光板の射出成形金型は、キャビティ形成面を構成するスタンパの背面部に対して温調部材移動手段により高温制御部と低温制御部が選択的に当接可能な温調部材を設けたことにより、成形される導光板の転写を良好にするとともに、溶融樹脂の流動を良好にすることにより隅部のヒケをなくすことができる。また溶融樹脂の冷却を早く行うことができ、成形サイクルを向上させることができる。
【図面の簡単な説明】
【図１】本発明の導光板の射出成形金型の射出充填前の断面図である。
【図２】本発明の導光板の射出成形金型の図１におけるＡ−Ａ線における断面図である。
【図３】本発明の導光板の射出成形金型の可動金型を固定金型側から見た図である。
【図４】本発明の導光板の射出成形金型の冷却時の断面図である。
【図５】本発明の導光板の射出成形金型の導光板取出時の断面図である。
【図６】本発明の別の実施の形態の導光板の射出成形金型の断面図である。
【符号の説明】
１　………　固定盤
２　………　固定金型
３　………　可動盤
４　………　可動金型
５，１５　……　取付板
６，１６　……　本体部
７　………　スプルブッシュ
８　………　溶融樹脂通路
９　………　鏡面板
１０　……　ゲート部
１１，２５　……　温調用媒体通路
１２，２９　……　管路
１３，３８ａ，３８ｂ，４２　……　キャビティ形成面
１４，４４　……　当接面
１７　……　枠体部
１８　……　連通孔部
１９　……　温調部材
２０　……　ガイド溝
２１　……　爪部
２２，３７……　油圧シリンダ
２３　……　ヒーター
２４　……　高温制御部
２６　……　低温制御部
２７，３２，３３……　断熱部
２８　……　電線
３０，３１　……　延設部
３４　……　スタンパ
３４ａ　……　背面部
３４ｂ　……　転写面
３４ｃ　……　周辺部
３４ｄ　……　側端部
３５　……　スタンパ取付面
３６　……　スタンパ押え部材
３９ａ，３９ｂ　……　スライドブロック
４０，４１　……　側面
４３　……　エア吸引管路
４５　……　ブラケット
４６　……　エア供給管路
４７　……　管路
４８　……　取出機
４９　……　吸盤
Ｃ　………　キャビティ
Ｐ　………　導光板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an injection molding method and an injection molding method for injecting a molten resin into a cavity forming surface formed in a flat shape between a fixed mold and a movable mold with a molten resin to mold a light guide plate or the like which is a flat resin molded product. It is about type.
[0002]
[Prior art]
Conventionally, injection molding of a light guide plate, which is a flat resin molded product, is performed by injection compression molding disclosed in JP-A-2000-229343 or the like in order to improve transfer to a stamper attached to a mold. It is performed by a molding method such as injection press molding described in Japanese Patent Application No. 218654. However, the above-described method of molding the light guide plate compresses the molten resin injected into the cavity by moving the movable mold only in the thickness direction of the light guide plate to be molded. In some cases, sink marks (insufficiently filled with molten resin) occurred near each corner including the corner of the light guide plate on the side. In particular, when a light guide plate is formed, a gate portion cannot be provided on the light entrance surface or the light exit surface because traces of the gate remain, and a gate portion is often formed on the other side of the light entrance surface. It was important to solve the problem of sink marks. Further, in the case of performing compression by moving the movable mold only in the thickness direction of the light guide plate to be molded as described in the above publication, the thickness of the light guide plate is controlled by controlling the amount of the molten resin to be injected and filled and the mold clamping cylinder. There is a problem that the accuracy of the thickness of the light guide plate is difficult to obtain due to the delicate difference in the amount. Furthermore, in recent years, with the increase in the size of the screen of a personal computer or the like, the light guide plate itself is also required to be large and thick, but when molding a large and thick light guide plate, it is particularly necessary to cool the light guide plate. There was a problem that the molding cycle was slow because of the time required.
[0003]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to mold a flat resin molded product such as a light guide plate having no sink near the corner. It is another object of the present invention to improve the transferability of the light guide plate to be molded and to speed up the molding cycle.
[0004]
[Means for Solving the Problems]
In the injection molding method for a flat resin molded product according to the first aspect, the shape of the flat resin molded product, which is a molded product, is formed between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold. A cavity formed following the cavity is formed, a molten resin is injected and filled into the cavity from a gate portion communicating with the cavity, and the cavity forming surface is formed along the mold opening / closing direction and forms a side end surface of the flat resin molded product. At least one is moved in a direction substantially perpendicular to the mold opening and closing direction to compress the molten resin in the cavity. Therefore, sink marks near the corners of the flat resin molded product can be eliminated.
[0005]
The injection molding method for a light guide plate according to claim 2, wherein the transfer surface is formed between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold according to the shape of the light guide plate as a molded product. A cavity provided with a stamper is formed, and a molten resin is injected and filled into the cavity from a gate portion communicating with the cavity, and at least a cavity forming surface formed along the mold opening / closing direction and forming a side end surface of the light guide plate. One is moved in a direction substantially perpendicular to the mold opening and closing direction along the stamper, and the molten resin in the cavity is compressed. Therefore, sink marks near corners of the light guide plate can be eliminated.
[0006]
The injection molding die of the light guide plate according to claim 3 is formed and transferred between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold according to the shape of the light guide plate as a molded product. A cavity provided with a stamper having a surface is provided, and the cavity has at least one of a cavity forming surface formed substantially perpendicular to the stamper and a mold opening / closing direction along the stamper. A moving means for moving in a right angle direction is provided. Therefore, sink marks near corners of the light guide plate can be eliminated.
[0007]
According to a fourth aspect of the present invention, in the injection molding die for a light guide plate according to the third aspect, the cavity forming surface moved by the moving means is a cavity forming surface forming a light incident surface of the light guide plate to be molded. I do. Therefore, sink marks near the light incident surface of the light guide plate to be formed can be eliminated.
[0008]
According to a fifth aspect of the present invention, in the injection molding die for a light guide plate, the gate portion is provided on the other side of the cavity forming surface moved by the moving means. Therefore, sink marks near corners far from the gate can be eliminated.
[0009]
The injection molding die of the light guide plate according to claim 6 is formed and transferred between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold according to the shape of the light guide plate as a molded product. A temperature control member provided with a cavity having a stamper having a surface, and a high-temperature control unit and a low-temperature control unit disposed on the back side of the stamper moves along the back surface of the stamper by the temperature control member moving means. It is characterized by being provided as possible. Therefore, the transfer to the light guide plate to be formed can be improved, and the cooling can be performed quickly, and the forming cycle can be improved.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of a light guide plate of the present invention before injection filling of an injection mold. FIG. 2 is a sectional view taken along line AA in FIG. FIG. 3 is a view of the movable mold of the injection molding mold of the light guide plate of the present invention as viewed from the fixed mold side. FIG. 4 is a cross-sectional view of the light guide plate of the present invention when the injection mold is cooled. FIG. 5 is a cross-sectional view of the injection molding die of the light guide plate of the present invention when the light guide plate is taken out.
[0011]
In FIG. 1, the injection mold for the light guide plate P of the present invention comprises a fixed mold 2 attached to a fixed platen 1 and a movable mold 4 attached to a movable platen 3. When the movable mold 4 is matched with the movable mold 4, a flat cavity C following the shape of the light guide plate P can be formed by the fixed mold facing surface of the movable mold 4 and the movable mold facing surface of the fixed mold 2. It is provided in. The fixing die 2 of the injection molding die of the light guide plate P will be described first. The fixing die 2 includes a mounting plate 5 for mounting the fixing die 2 to the fixing plate 1 by bolts, and a main body fixed to the mounting plate 5. 6, a sprue bush 7 formed substantially at the center of the mounting plate 5, a molten resin passage 8 which communicates with the sprue bush 7 and is formed inside the main body 6, and a protrusion which is mounted on a side of the main body 6 opposite to the mounting plate. The mirror plate 9 includes a gate plate 10 and the like, which communicate with the molten resin passage 8 and are formed on the mirror plate 9. A temperature control medium passage 11 is formed inside the mirror plate 9, and a temperature control medium is sent from a temperature controller (not shown) via a pipe 12 so that the temperature of the mirror plate 9 can be adjusted. A flat cavity forming surface 13 forming the cavity C is formed on the movable mold facing surface on the side opposite to the main body of the mirror surface plate 9. Further, a contact surface 14 that contacts the movable mold 4 is formed on the movable mold facing surface of the main body 6.
[0012]
Next, the movable mold 4 will be described. The movable mold 4 includes a mounting plate 15 for mounting the movable mold 4 to the movable platen 3 with bolts, and a main body 16 fixed to the mounting plate 15. As shown in FIGS. 2 and 3, a frame portion 17 having a space in which a part of the cavity C is formed is fixed to the center of the main body 16 on the side opposite to the mounting plate. A communication hole 18 having an opening having a predetermined dimension is formed between the main body 16 and the frame 17 so as to penetrate the movable mold 4 in the vertical direction. The cavity C near the middle of the communication hole 18 is closed by a stamper 34 described later. A temperature control member 19 having a mirror surface is accommodated in a space surrounded by the communication hole 18 and the stamper 34. Therefore, the temperature control member 19 is housed on the back surface 34a side of the stamper 34.
[0013]
The temperature control member 19 includes a high-temperature control unit 24 in which the heater 23 is fixed to the stamper 34 side (front side) and a low-temperature control unit 26 in which a temperature control medium passage 25 is formed. It is arranged. The heater 23 of the high temperature control unit 24 is connected to an electric wire 28 from a power supply (not shown), and the low temperature control unit 26 is connected to a conduit 29 from a temperature controller (not shown). Temperature control is provided. Extension portions 30 and 31 are provided on the outer portion of the high temperature control portion 24 and the outer portion of the low temperature control portion 26, respectively, and a heat insulating portion 32 is provided between the high temperature control portion 24 and the extension portion 30. Have been. A heat insulating part 33 is also provided between the low temperature control part 26 and the extension part 31, and a temperature control member moving means fixed to the movable mold 4 by a bracket 45 is provided on the extension part 31. A rod 22a of a certain hydraulic cylinder 22 is fixed. As shown in FIG. 2, claws 21 are provided on both sides of the temperature control member 19 as viewed in cross section, and the temperature control member 19 is provided with a guide formed on the side of the frame body 17 inside the communication hole 18. The claw portion 21 is guided by the groove 20. The temperature control member 19 is guided by the guide groove 20 by the driving of the hydraulic cylinder 22 and moves in the direction in which the high temperature control unit 24 and the low temperature control unit 26 are disposed along the back surface 34 a of the stamper 34. It is provided as possible.
[0014]
A predetermined interval is provided between the side surface of the temperature control member 19 including a portion between the claw portion 21 of the temperature control member 19 and the guide groove 20 and the side of the frame body portion 17. It can respond to thermal expansion. The surface of the temperature control member 19 on the side of the stamper 34 and the back surface 34a of the stamper 34 are formed as lubricating surfaces. Further, the temperature control member 19 and the main body 16 are provided with means for facilitating the movement of the temperature control member 19. In this embodiment, an air supply pipe 46 is formed inside the main body 16, and the air supply pipe 46 is opened on the main body 16 side of the temperature control member 19. The air supply pipe 46 is connected to a compressed air supply means (not shown) through a pipe 47, and the air is supplied from the air supply means to facilitate movement of the temperature control member 19 in the communication hole 18. I have to. Further, in addition to the above, between the main body 16 and the temperature control member 19, a mutual surface may be a lubricating surface, or a roller bearing or the like may be provided.
In this embodiment, the temperature control member 19 is attached only to the movable mold 4 to which the stamper 34 is attached. However, the temperature control member 19 is attached to the movable mold 4 and the fixed mold 2 for the purpose of preventing the molded product from warping. You may.
[0015]
As shown in FIG. 2, a stamper mounting surface 35 is formed in the frame 17 on the fixed die 2 side of the guide groove 20 in a direction substantially perpendicular to the mold opening and closing direction. Has a stamper 34 attached. The stamper 34 is a thin plate made of nickel and having a thickness of 0.3 mm to 1.5 mm, and a portion constituting the cavity C on the surface side is a transfer surface 34b for forming a pattern on the light guide plate P. In this embodiment, the stamper 34 is attached to the fixed mold facing surface of the movable mold 4, but the fixed mold facing surface of the movable mold 4 and / or the movable mold facing surface of the fixed mold 2. The temperature control member 19 may also be provided on the fixed mold 2 side corresponding to the stamper 34.
A stamper pressing member 36 having a predetermined length is fixed to four portions of the frame portion 17 corresponding to the flat stamper 34, and presses a peripheral portion 34 c of the stamper 34. The space between the stamper holding member 36 and the peripheral portion 34c of the stamper 34 is formed at a small interval where the molten resin does not enter, and a space is formed at the side end 34d of the stamper 34 by the stamper holding member 36. It can respond to thermal expansion.
[0016]
The frame 17 is provided with hydraulic cylinders 37 as moving means for moving the cavity forming surfaces 38a and 38b constituting the side end surfaces of the light guide plate P in a direction substantially perpendicular to the mold opening and closing direction. In this embodiment, the hydraulic cylinder 37 is provided with eight rods 37a facing the cavity C at a total of eight positions, four at the top and four at the frame 17, respectively. However, the moving means is not limited to the hydraulic cylinder 37, and a more precise movement of the cavity forming surfaces 38a and 38b may be performed by using a servomotor or a linear motor. Slide rods 39a and 39b having cavity forming surfaces 38a and 38b that form side ends of the molded product in the cavity C are mounted on the rod 37a of the hydraulic cylinder 37 on the side opposite to the mounting side of the rod 37a. I have. Accordingly, the slide blocks 39a and 39b are moved in a direction substantially perpendicular to the mold opening and closing direction along the peripheral portion 34c of the stamper 34, and the cavity forming surfaces 38a and 38b of the slide blocks 39a and 39b are transferred to the transfer surface of the stamper 34. That is, it is formed in a direction substantially perpendicular to the peripheral part 34b and the peripheral part 34c. The side surface 40 of the slide blocks 39a and 39b on the side of the stamper 34 and the peripheral portion 34c of the stamper 34 are opposed to each other with a small gap in which the molten resin does not enter. Further, when the fixed mold 2 and the movable mold 4 are combined, the side surface 41 of the slide blocks 39a and 39b on the mirror plate 9 side and the cavity forming surface 13 of the mirror plate 9 also have a small amount of molten resin. They are provided so as to face each other at an appropriate interval.
[0017]
In this embodiment, as shown in FIG. 3, among the cavity forming surfaces formed substantially perpendicular to the stamper 34, the cavity forming surfaces 38a and 38b that form the light incident surface of the light guide plate P are slide blocks. The other two left and right surfaces 39a and 39b are immovable cavity forming surfaces 42. However, the slide block may have only the cavity forming surface on the other side of the gate portion 10 among the cavity forming surfaces in a direction substantially perpendicular to the stamper 34, or at least one or all of the four surfaces may be the slide block. The cavity forming surface 38a and / or the cavity forming surface 38b are divided into a plurality of surfaces in order to form irregularities on the side surfaces of the light guide plate necessary when the light guide plate P is mounted on a personal computer or the like. It may be.
[0018]
In this embodiment, the mirror portion 9 of the stationary mold 2 on the other side of the cavity forming surface 38a is provided with a gate portion 10 which is closed by the movement of the slide block 39b. As shown in FIG. 2, an air suction pipe 43 connected to a negative pressure means (not shown) is formed on the stamper mounting surface 35 of the frame portion 17, and the stamper 34 pressed by the stamper pressing member 36 is formed. Is provided so as to be able to suck the peripheral end of the back surface portion 34a. The fixed mold opposing surface of the frame portion 17 is a contact surface 44, which is in contact with the contact surface 14 of the fixed mold 2 when the molds are matched.
[0019]
Next, a method of forming the light guide plate P using an injection molding die for the light guide plate P in this embodiment will be described. The light guide plate P formed by the injection molding die of the light guide plate P in this embodiment has a uniform thickness, has light incident surfaces on both side end surfaces, and has fine dots or dots formed on one surface by a stamper 34. Although the pattern formed of the grooves is formed, the light guide plate P to be formed may have a pattern formed on both sides by the stamper 34, and the light incident surface is not limited to two. The shape of the light guide plate P is not limited to a uniform thickness, and may be a wedge-shaped light guide plate. However, in the case of a wedge-shaped light guide plate, it is necessary to provide the slide block so as to be movable in a direction in which the cross-sectional area of the cavity C is constant. Further, in this embodiment, the light guide plate P is formed of acrylic, but other transparent resins such as polycarbonate and cycloolefin resin may be used.
[0020]
First, before the step of injecting and filling the molten resin from the injection device (not shown) into the cavity C of the injection molding die of the light guide plate P, the slide blocks 39a and 39b are retracted to increase the volume of the cavity C. At the same time, the high temperature control unit 24 of the temperature control member 19 is moved by the hydraulic cylinder 22 as the temperature control member moving means so as to correspond to the back surface portion 34a of the stamper 34, and the heater 23 is energized. Raise the temperature or preliminarily raise the temperature. The temperature of the stamper 34 is raised to 150 ° C. by the heat transfer from the high-temperature control unit 24, and the movable mold 4 is moved by a mold clamping device (not shown) so that the contact surface 44 of the movable mold 4 and the fixed mold 2 Before and after the contact surface 14 is brought into contact, the hydraulic cylinder 22 is driven to move the temperature control member 19 as shown in FIG. The portion of the temperature control member 19 abutting on the back surface 34a of the stamper 34 is switched from the high temperature control unit 24 to the low temperature control unit 26. In this embodiment, the temperature control member 19 is in direct contact with the back surface 34a of the stamper 34. However, a heat storage member made of an iron plate or the like having a thickness of 1 to 5 mm is attached to the back surface 34a of the stamper 34. Alternatively, the temperature control member 19 may be brought into contact with the stamper 34 via the iron plate. By doing so, it is possible to delay the cooling of the stamper 34 from the time when the low-temperature control unit 26 comes into contact with the stamper 34 to the time when the injection filling is started.
When the temperature control member 19 is moved and the mold is clamped, a step of injecting and filling the molten resin into the cavity C from the injection device (not shown) via the sprue bush 7, the molten resin passage 8, and the gate portion 10 is performed. In this embodiment, the molten resin is injected and filled at 280 ° C. at an injection pressure of 80 MPa.
[0021]
Next, a step of moving the slide blocks 39a and 39b forward along the stamper 34 by the hydraulic cylinder 37 as a moving means to compress the molten resin injected and filled is performed. The movement of the slide blocks 39a and 39b at this time may be started during or after the injection of the molten resin is completed. In this embodiment, the gate block 10 is closed by moving the slide block 39b. In particular, when the gate portion 10 is located on the other side of the cavity C in the cavity C with respect to the cavity forming surface 38a of the slide block 39a where the light incident surface is formed, the effect of eliminating sink marks near the light incident surface is great. In this embodiment, the movement of the slide blocks 39a and 39b is performed at the same time, but the movement timing of the slide blocks 39a and 39b may be shifted.
[0022]
When the injection filling of the molten resin is completed and the transfer to the molten resin is completed by the transfer surface 34b of the stamper 34, the back surface 34a of the stamper 34 is controlled to about 50 ° C. by a temperature controller (not shown) as described above. Since the low-temperature control unit 26 of the temperature control member 19 is in contact with the low-temperature control unit 26, the stamper 34 in which the back surface 34a is in contact with the low-temperature control unit 26 is rapidly cooled, and the cavity is cooled via the cooled stamper 34. Cooling of the molten resin in C is promoted. When the cooling of the molten resin is completed, as shown in FIG. 5, the slide blocks 39a and 39b are retracted by the hydraulic cylinder 37, and the light guide plate P formed with the cavity forming surfaces 38a and 38b of the slide blocks 39a and 39b. Is released from the side surface. When the mold is opened by the mold clamping device, the take-out machine 48 is moved between the fixed mold 2 and the movable mold 4, and the light guide plate P formed by the suction cup 49 of the take-out machine 48 is adsorbed and taken out. Is performed. Then, the hydraulic cylinder 22 is driven until the next molding, and the high temperature control unit 24 of the temperature control member 19 is moved to the back surface 34 a of the stamper 34 again.
[0023]
Next, another embodiment shown in FIG. 6 will be described.
In the injection molding die of another embodiment shown in FIG. 6, both the compression in the mold opening and closing direction and the compression in the direction parallel to the transfer surface of the stamper are performed on the molten resin injected and filled in the cavity C. And a molding method such as injection compression molding or injection press can be performed. The differences from the embodiment shown in FIGS. 1 to 5 will be mainly described. In another embodiment shown in FIG. 6, the fixed mold 51 includes a main body 52 and a mirror plate 53 or the like attached to the movable mold side (front surface) of the main body 52, and the movable mold of the mirror plate 53. A stamper 55 having a transfer surface 55a that is a cavity forming surface is attached to the facing surface. A contact surface 56 is provided on the movable mold facing surface of the main body 52, and the mirror plate 53 and the contact surface 56 of the main body 52 are formed in a substantially planar shape.
[0024]
The movable mold 54 is provided with a main body 57 and a mirror plate 58 attached to the front surface of the main body 57, and a cavity forming surface 59 is formed on a surface of the mirror plate 58 facing the fixed mold. . A frame 60 is formed around the main body 57, and the plurality of springs 61 fixed between the main body 57 and the frame 60 allow the frame 60 to open and close with respect to the main body 57. The position in the direction is variably provided. In addition, a contact surface 62 that contacts the fixed mold 51 is formed on the fixed mold facing surface of the frame body portion 60. Further, steps 63a and 63b are formed between the main body 57 and the frame 60, and the frame 60 is provided so as to be unable to retreat from a predetermined position by the contact of the steps 63a and 63b. I have.
[0025]
A plurality of hydraulic cylinders 64 are provided on the frame portion 60 with the rods 64a facing the cavities C, and the slide blocks 65 are fixed to the rods 64a of the hydraulic cylinders 64. The slide block 65 is provided so as to be movable in parallel with the transfer surface 55 a of the stamper 55 by driving the hydraulic cylinder 64. On the side of the slide block 65 opposite to the surface on which the rod 64a is fixed, a cavity forming surface 66 is provided in a direction substantially perpendicular to the transfer surface 55a of the stamper 55. When the frame portion 60 is most retracted, the side surface 67 of the slide block 65 on the side of the mirror plate 58 and the cavity forming surface 59 of the mirror plate 58 are set so as to have a small gap where the molten resin does not enter. . Further, another cavity forming surface 69 is formed in a direction substantially perpendicular to the transfer surface 55a of the stamper 55 inside the frame portion 60 where the slide block 65 is not provided. In this embodiment, the gate portion 68 is formed on a cavity forming surface 69 formed in a direction substantially perpendicular to the transfer surface 55a of the stamper 55 on the movable mold 54 side.
[0026]
Next, a method of forming the light guide plate P using an injection mold for the light guide plate P according to another embodiment shown in FIG. 6 will be described. Before the molten resin is injected and filled into the cavity C, the hydraulic cylinder 64 is used. The slide block 65 is retracted. The movable mold 54 is advanced by a mold clamping device (not shown), and when the contact surface 62 of the movable mold 54 and the contact surface 56 of the fixed mold 51 abut, the mold clamping force by the mold clamping device is maintained at a constant pressure. To hold. At this time, the frame body 60 is moved by a predetermined amount from the position of the frame body 60 when not in contact with the fixed mold 51 by a predetermined amount due to the balance between the mold clamping force and the urging force of the spring 61. It will be in the retracted position. Next, a molten resin is injected and filled into the cavity C from a not-shown injection device via the gate portion 68. When the molten resin is injected and filled into the cavity C, the mold clamping force by a mold clamping device (not shown) is increased to further contract the spring 61 and compress the molten resin in the cavity C in the mold opening and closing direction. When the step 63a of the main body 57 and the step 63b of the frame body 60 come into contact with each other, the mold clamping force by the mold clamping cylinder is maintained so as to maintain the position. Next, the hydraulic cylinder 64 is advanced, and the molten resin in the cavity C is compressed by the slide block 65. As described above, the molten resin in the cavity C is compressed in both the mold opening / closing direction and the direction substantially perpendicular to the mold opening / closing direction, and the light guide plate P is formed. In the case of this embodiment, the forward stroke by the slide block 65 may be set to a small stroke of, for example, about 1 mm, and the slide block 65 compresses only a part of any one of the cavity forming surfaces 66. You may do so.
[0027]
In the embodiment of the present invention, the injection molding of the light guide plate P has been described as an example, but the present invention can be used for injection molding of other flat resin molded products. For example, it can be used for molding a fuel cell separator, a frame of a personal computer, or the like. The molded article may have irregularities or holes, and may be used resin materials and other molding conditions. There is no particular limitation as long as the present invention can be implemented.
[0028]
【The invention's effect】
The injection molding method and injection molding die for a flat resin molded product according to the present invention is a flat resin molded product formed between a fixed mold facing surface of a movable mold and a movable mold facing surface of a fixed mold. A cavity formed according to the shape of the product is formed, and molten resin is injected and filled into the cavity from a gate portion communicating with the cavity, and is formed along the mold opening and closing direction to form a side end surface of the flat resin molded product. At least one of the cavity forming surfaces is moved in a direction substantially perpendicular to the mold opening / closing direction to compress the molten resin in the cavity. Therefore, sink marks at corners of the flat resin molded product can be eliminated. In particular, by making the cavity forming surface on the other side of the gate portion a movable cavity forming surface, sink marks in a portion far from the gate portion can be eliminated, and in the light guide plate, sink marks on the light incident surface can be eliminated. .
[0029]
Further, the injection molding die of the light guide plate of the present invention is characterized in that the temperature control member which the high temperature control unit and the low temperature control unit can selectively contact with the back surface of the stamper constituting the cavity forming surface by the temperature control member moving means. Is provided, the transfer of the light guide plate to be molded can be improved, and the flow of the molten resin can be improved, thereby eliminating sink marks at the corners. In addition, the molten resin can be cooled quickly, and the molding cycle can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a light guide plate of the present invention before injection filling of an injection mold.
FIG. 2 is a cross-sectional view of the injection mold for a light guide plate of the present invention taken along line AA in FIG.
FIG. 3 is a view of the movable mold of the injection molding mold of the light guide plate of the present invention as viewed from the fixed mold side.
FIG. 4 is a cross-sectional view of the light guide plate of the present invention when the injection mold is cooled.
FIG. 5 is a cross-sectional view of the injection molding die of the light guide plate of the present invention when the light guide plate is taken out.
FIG. 6 is a cross-sectional view of an injection mold for a light guide plate according to another embodiment of the present invention.
[Explanation of symbols]
1 ... fixed board
2 ……… Fixed mold
3 movable board
4 ……… Movable mold
5,15 ...... Mounting plate
6,16 ...... Body part
7 ... Spruce bush
8 ... molten resin passage
9 Mirror plate
10 ... Gate part
11, 25… Temperature control medium passage
12,29 …… conduit
13, 38a, 38b, 42 ... cavity forming surface
14,44… Contact surface
17 ... Frame part
18 Communication hole
19 ...... Temperature control member
20 …… Guide groove
21 ... nail part
22, 37 ... Hydraulic cylinder
23 ...... heater
24 High temperature control unit
26 ...... Low temperature control unit
27, 32, 33 ... heat insulation part
28 ...... Electric wire
30, 31 ... Extension part
34 ...... Stamper
34a… back part
34b Transfer surface
34c ...... Peripheral part
34d ... side end
35 ...... Stamper mounting surface
36 ...... Stamper holding member
39a, 39b ... slide block
40, 41 ... side
43 …… Air suction line
45 ...... Bracket
46 …… Air supply pipeline
47 …… Pipe
48 ...... Unloader
49 ...... Sucker
C ……… Cavity
P ...... Light guide plate

Claims

A cavity formed between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold in accordance with the shape of a flat resin molded product which is a molded product;
A gate portion communicating with the cavity is provided;
In the injection molding method of a flat resin molded product to obtain a molded product by injection filling a molten resin into the cavity from the gate portion,
A cavity forming surface formed along the mold opening / closing direction in the cavity and forming a side end surface of the flat resin molded product;
Moving means for moving at least one of the cavity forming surfaces in a direction substantially perpendicular to the mold opening and closing direction is provided,
Injecting and filling molten resin into the cavity from the gate portion,
At least one of the cavity forming surfaces is moved by the moving means,
An injection molding method for a flat resin molded product, comprising a step of compressing the molten resin in the cavity.

A cavity formed between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold according to the shape of the light guide plate as a molded product;
A stamper having a transfer surface that is attached to the fixed mold facing surface of the movable mold and / or the movable mold facing surface of the fixed mold and forms a part of the cavity;
A gate portion communicating with the cavity is provided;
In the injection molding method of a light guide plate for obtaining a molded product by injection filling a molten resin into the cavity from the gate portion,
A cavity forming surface formed in the cavity in a direction substantially perpendicular to the stamper;
Moving means for moving at least one of the cavity forming surfaces along the stamper in a direction substantially perpendicular to the mold opening and closing direction is provided,
Injecting and filling molten resin into the cavity from the gate portion,
At least one of the cavity forming surfaces is moved by the moving means,
An injection molding method for a light guide plate, comprising a step of compressing the molten resin in the cavity.

A cavity formed between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold according to the shape of the light guide plate as a molded product;
A stamper having a transfer surface that is attached to the fixed mold facing surface of the movable mold and / or the movable mold facing surface of the fixed mold and forms a part of the cavity;
In an injection mold of a light guide plate provided with a gate portion communicating with the cavity,
A cavity forming surface formed in the cavity in a direction substantially perpendicular to the stamper;
A mold for injection molding a light guide plate, comprising: moving means for moving at least one of the cavity forming surfaces along the stamper in a direction substantially perpendicular to the mold opening / closing direction.

The injection molding die for a light guide plate according to claim 3, wherein the cavity forming surface moved by the moving means is a cavity forming surface forming a light entrance surface of the light guide plate to be molded.

The injection molding die for a light guide plate according to claim 3, wherein the gate portion is provided on the other side of the cavity forming surface moved by the moving means.

A cavity formed between the fixed mold facing surface of the movable mold and the movable mold facing surface of the fixed mold according to the shape of the light guide plate as a molded product;
A stamper having a transfer surface that is attached to the fixed mold facing surface of the movable mold and / or the movable mold facing surface of the fixed mold and forms a part of the cavity;
In an injection mold of a light guide plate provided with a gate portion communicating with the cavity,
On the back side of the stamper,
A temperature control member in which the high-temperature control unit and the low-temperature control unit are disposed with the heat insulating unit interposed therebetween
In the direction in which the high temperature control unit and the low temperature control unit are disposed,
A mold for injection molding a light guide plate, comprising: a temperature control member moving means movable along a rear surface of the stamper.