JP3918386B2 - Method and apparatus for controlling mold clamping force of injection molding machine - Google Patents

Method and apparatus for controlling mold clamping force of injection molding machine Download PDF

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JP3918386B2
JP3918386B2 JP33759299A JP33759299A JP3918386B2 JP 3918386 B2 JP3918386 B2 JP 3918386B2 JP 33759299 A JP33759299 A JP 33759299A JP 33759299 A JP33759299 A JP 33759299A JP 3918386 B2 JP3918386 B2 JP 3918386B2
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clamping force
mold
mold clamping
molding machine
injection molding
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JP2001150505A (en
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悦雄 岡原
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Ube Corp
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Ube Industries Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/76—Measuring, controlling or regulating
    • B29C45/7653—Measuring, controlling or regulating mould clamping forces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76003—Measured parameter
    • B29C2945/76013—Force
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76177—Location of measurement
    • B29C2945/76224—Closure or clamping unit
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76344—Phase or stage of measurement
    • B29C2945/76391—Mould clamping, compression of the cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76494—Controlled parameter
    • B29C2945/76505—Force
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76655—Location of control
    • B29C2945/76702—Closure or clamping device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76822—Phase or stage of control
    • B29C2945/76869—Mould clamping, compression of the cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76929—Controlling method
    • B29C2945/76939—Using stored or historical data sets
    • B29C2945/76943—Using stored or historical data sets compare with thresholds

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、射出成形機における型締力制御方法とその装置に関し、特に、薄い成形品を低圧で無理なく成形し、残留応力や変形の少ない良品質の成形品を効率的に生産することができる射出成形機の型締力制御方法とその装置に関する。
【０００２】
【従来の技術】
従来の射出成形においては熟練したオペレータが成形品サイズや成形材料等の成形条件を考慮して経験的に型締力を予測し、試し打ちを行うことにより試行錯誤的に型締力を決定していた。このため、熟練度の高いオペレータは溶融樹脂の射出充填中にバリの発生しない範囲で金型が開き、キャビティ中および溶融樹脂から発生するガスを排出できる程度の低い型締力で成形を行っていた。特に、ＣＤディスクのような薄い製品を成形する場合にはできるだけ低圧で成形し、成形品に残留応力が残らないようにすることにより成形品の変形を防止するとともに成形品の複屈折等光学的品質の低下を防止していた。
【０００３】
しかしながら、溶融樹脂の射出充填が進むにつれて大きくなる型開力（金型を開こうとする力であり、以後は樹脂反力とも言う）に対応した必要最低限の型締力（後述する）を負荷することはできなかった。即ち、成形サイクルをスタートする前に設定した型締力を、成形サイクル中に時々刻々変化する樹脂反力に対応して型締力を変更していく制御方法は行われていなかった。従って、必要以上の型締力が負荷されており、ＣＤディスクのような薄い製品を光学的に満足できる品質レベルで得ることは困難であった。
【０００４】
一方、一般的なオペレータでは上記のような型締力の設定は期待できないので、必要以上の型締力が負荷されるため成形品の残留応力が大きくなって、成形品の変形や複屈折率が大きくなり良品を得るのは困難であった。また、過大な型締力が作用するので、金型の消耗も激しくメンテナンスにも余分な手間がかかっていた。
以上のような問題を解決した先行技術としては特開平８−２７６４７９号公報がある。
【０００５】
この先行技術においては、ディスク基板用金型の可動金型と固定金型を成形機の可動盤と固定盤にそれぞれ取付け、型閉動作により前記可動金型が固定金型に対して０〜０．５ｍｍの予め定められた距離まで移動した際に、射出装置のノズルから前記ディスク基板用金型のキャビティ内に溶融樹脂の射出を開始するとともに、前記可動金型が固定金型に当接したことを検出して、前記型締シリンダの型締側に供給する油圧を調整して型締力を定格型締力の略１０〜４０％に相当する予め定めた値に維持するようにし、射出工程終了後、前記型締シリンダの型締側に供給する油圧を昇圧して、１段または複数段の型締圧力制御を行い、定格の型締力で、キャビティ内の溶融樹脂の冷却工程を行う技術が開示されている。
【０００６】
しかしながら、上記先行技術においても、型締力の低圧化の程度は充分ではなく、必要最低限以上の型締圧力が負荷されている。また、定格型締力の略１０〜４０％に相当する型締力が負荷されるタイミングや型締力と樹脂反力との関係が明確ではなく、型締力が負荷された後に射出充填が完了することもある。この場合にはガス抜けが不充分になる恐れがある。また、射出工程終了前に樹脂反力が型締力より大きくなり、一度金型が閉じて定格の１０〜４０％の小さな型締力が負荷された後に金型が再度開いてバリが発生する恐れもある。
【０００７】
段落番号０００３で述べた必要最低限の型締力とは金型合せ面が開いてもバリが発生しない程度に固定金型と可動金型との間に僅かに隙間の開いた状態を射出工程中に常に維持するために必要な型締力であり、樹脂の充填挙動により変動するものである。即ち、射出充填の初期には金型キャビティ内の一部にしか樹脂が充填されていないので、充填された樹脂による金型を開かせる力は小さく、充填が進むにつれてこの樹脂反力は大きくなる。
【０００８】
また、金型キャビティ内には空気が存在しており、高速で溶融樹脂が充填される射出成形においては、この空気は金型外へ速やかに排出させる必要がある。この場合、固定金型と可動金型が大きな力で締め付けられていると空気の逃げ場がなくなり、金型内の空気は断熱圧縮されて高温になり成形品にガス焼けを発生させるとともに一部は溶融樹脂中に入りボイドという成形品欠陥の原因となる。また、ガス抜きを良くするために金型合せ面にガス抜き通路を設けると、この部分より溶融樹脂が漏れてバリが発生し成形不良となる。
【０００９】
【発明が解決しようとする課題】
以上のような問題を解決し、オペレータの熟練度に左右されないで、必要最低限の型締力が自動的に負荷される射出成形機の型締力制御方法およびその装置を提供することにある。
【００１０】
【課題を解決するための手段】
上記の課題を解決するために、本発明においては、第１の発明では、可動金型と固定金型の両金型を閉じて該両金型間に形成される金型キャビティ内へ溶融樹脂を射出充填して成形品を得るためにトグルを用いた射出成形機の型締力制御方法において、型締力保持期間中に該金型に付与された型締力を型締力検出手段により検出された検出値を演算して得られた実効型締力と、ドライサイクル状態下における該両金型の型合わせ状態時のクロスヘッド位置とその時得られた検出値を演算して得られた設定型締力との関係に基いて、前記実効型締力から前記設定型締力を差引いた型締力値が予め設定した許容値に入るようにクロスヘッド位置を制御することにより、型締期間中に該両金型間に必要最低限の型締力を付与することとした。
【００１１】
また、第２の発明では、第１の発明における溶融樹脂を金型キャビティ内に射出充填中および保圧期間も常に前記実効型締力が前記設定型締力よりも大きくなるようにクロスヘッド位置を制御することとした。
更に、第３の発明では、第１の発明における溶融樹脂を金型キャビティ内に射出充填した後の保圧期間中および冷却期間も常に前記実効型締力が前記設定型締力よりも大きくなるようにクロスヘッド位置を制御することとした。
【００１２】
次に、第４の発明では、可動金型と固定金型の両金型を閉じて該両金型間に形成される金型キャビティ内へ溶融樹脂を射出充填して成形品を得るためにトグルを用いた射出成形機の型締力制御装置において、型締力保持期間中に該金型に付与された型締力を型締力検出センサにより検出する型締力検出部と、ドライサイクル状態下で両金型の型合わせをした際のクロスヘッド位置とその時の型締力検出値に基いて演算される型締力の関係を記憶する記憶部と、実成形サイクル中に型締力検出部よりの検出値に基いて実効型締力を演算する演算部と、演算部で演算された実効型締力と入力されている初期型締力とを比較する比較制御部と、金型タッチ点よりのクロスヘッドの移動量を検出するクロスヘッド位置検出部と、比較制御部からの信号を受けて型締シリンダ制御部に型締力の指令値を発する型締制御部と、型締制御部で得られた情報に基づきクロスヘッドを前後動させる型締作動機構制御部と、少なくとも初期型締力と実効型締力より初期型締力又は設定型締力を差し引いた型締力値の許容値と型締力の上昇幅／下降幅とを設定する型締条件設定部とを有する構成とした。
【００１３】
また、第５の発明では、第４の発明におけるトグルを駆動する機構がサーボモータとボールネジ機構からなる構成とした。
【００１４】
【作用】
本発明によれば、型締期間中に金型に負荷されている実際の型締力（本発明では実効型締力と定義している）を型締装置の型締力伝達部材の応力を測定し演算することにより算出している。また、溶融樹脂を射出しない状態（ドライサイクルともいう）で金型の型合せを行い、この状態からクロスヘッドを前進させてクロスヘッド位置と前記実効型締力の関係を求めておく。
一方、実成形サイクルにおいては溶融樹脂の充填圧力により金型を開かせようとする力即ち、樹脂反力が発生する。この樹脂反力は射出充填が進むにつれて大きくなり、その後充填された樹脂の冷却の進行とともにこの樹脂反力は小さくなる。
【００１５】
以下図２に基づいて説明する。、ドライサイクル時の両金型が接触したいわゆるタッチ点Ａ（型締力が０である型合せした状態）からのクロスヘッド位置と型締力伝達部材の応力より求めた前記実効型締力との関係より、ある瞬間のクロスヘッド位置（点Ｂ）に相当するドライサイクル時の型締力（Ｆ１：線分ＣＢ）を求める。一方、このクロスヘッド位置での実成形サイクル中の型締力伝達部材の応力より求めた型締力、即ち実効型締力（Ｆ２：線分ＥＧ）は樹脂反力を受けるのでＦ１より大きくなっている。
Ｆ２＞Ｆ１ （１式）
また、型締力伝達部材の応力より求めた実効型締力（Ｆ２）と樹脂反力（Ｆ３：線分ＥＦ）、固定金型と可動金型との間に作用している型圧力（Ｆ４：線分ＦＧ）との関係は下記の通りとなる。
Ｆ２-Ｆ３＝Ｆ４ （２式）
このＦ４がマイナスとなった時には金型にスキマが空くことになる。このスキマが大きくなると溶融樹脂がキャビティ外に漏れ出してバリが発生することになる。一般的には、樹脂の種類や成形条件にもよるが、一般的には、このスキマが０〜０．２ｍｍの範囲にあればバリは発生しないと言われている。
【００１６】
本発明の技術思想の一つは、上記の型圧力（Ｆ４）をできるだけ小さくすることにより金型内のガス抜けを良くするとともに、キャビティ内の溶融樹脂にかかる型圧力を可能な限り小さくしてキャビティ内の溶融樹脂の流動を滑らかにすることにより成形品に残る残留応力を少なくし、成形品の変形を少なくするものである。
また、上記技術思想をプログラム制御により達成することにより、経験の少ないオペレータでも容易に、且つ、効率的に残留応力の少ない、光学的にも良品質の成形品を生産できる。
【００１７】
【発明の実施の形態】
以下、図面に基づいて本発明について説明する。図１〜図４は本発明の実施例に係り、図１は本発明に係るトグル式射出成形機の型締力制御装置の構成図、図２は本発明に係るクロスヘッド位置と実効型締力、樹脂反力等の説明図、図３は実効型締力と設定型締力の制御状態の説明図、図４は型締力制御のフローチャート図である。
【００１８】
本発明に使用するトグル式射出成形機の構成および動作について図１に基づいて説明する。射出成形機の型締装置１は、タイバー２の前端部に固定盤３を、タイバの後端部にリンクハウジング４を取付け、このリンクハウジング４にトグル駆動用（型締用）サーボモータ８が固定されている。サーボモータ８とボールネジ機構１１によりクロスヘッド１２を駆動することにより、トグルリンクを介してタイバ２上を摺動する可動盤５を固定盤３に対して離間接近させるものであり、この可動盤５に可動金型７が取付けられ、固定盤３に固定金型６が取付けられている。
【００１９】
型締力検出センサ１３としてタイバ２上に歪ゲージを貼り、その検出信号を型締力検出部３０に送信している。
クロスヘッド１２の位置検出センサ１４としてはリニアセンサを使用し、その検出信号をクロスヘッド位置検出部３１に送信している。本実施例ではトグル駆動機構としてサーボモータとボールネジ機構を採用しているのでサーボモータの回転角度よりクロスヘッド位置を算出することもできる。
【００２０】
次に、型締力制御装置の構成と機能について説明する。
初期型締力や型締速度、実効型締力と設定型締力との許容差、型締力の上昇／下降幅等を型締条件設定部３３に入力する。これらの入力値は型締制御部３４に送信される。成形サイクルを開始する前に、樹脂を射出しない状態（ドライサイクル）で型合せ位置からのクロスヘッドの位置（距離）と型締力（Ｆ１＝Ｆ２）の関係データを採り、記憶部３５に記憶させる。
【００２１】
型締条件設定部３３に入力されている初期型締力（Ｆ０）に基づいて型締制御部３４を経由して型締作動機構制御部３６の指令に基づき型締動作が行なわれる。型締動作が完了すると射出制御部（図示せず）より溶融樹脂の射出指令が行われ、金型キャビティ内へ溶融樹脂が充填される。
溶融樹脂の充填が進むにつれて樹脂反力（Ｆ３）が発生し、金型を開こうとする力に抗してタイバの応力が大きくなる。このタイバの応力を型締力検出センサ１３経由して型締力検出部３０で検出し、演算部３７でタイバに負荷されている力（実効型締力（Ｆ２））を演算・算出する。この算出された実効型締力（Ｆ２）と入力されている初期型締力（Ｆ０）とを比較制御部３８で比較する。
【００２２】
実効型締力（Ｆ２）より初期型締力（Ｆ０）を差し引いた値が予め型締条件設定部３３に入力されている許容値より大きくなると、予め型締条件設定部３３に入力されている型締力の上昇幅だけ型締力が大きくなるようにクロスヘッド位置を前進させる。この型締力上昇値とクロスヘッド位置の移動量（設定Ｂ）との関係は図２に示すように、成形サイクル開始前に採取したドライサイクル時のデータ、即ち、型合せ位置からのクロスヘッドの位置（距離）と型締力の関係より演算部３７で演算・算出される。クロスヘッド移動後の位置における図２に基づいて算出された型締力が、このクロスヘッド位置における設定型締力（Ｆ１）となる。
溶融樹脂の充填が進むと樹脂反力は更に大きくなり、実効型締力より前記設定型締力（射出開始時の値は初期型締力であった）を差し引いた値が予め型締条件設定部３３に入力されている許容値より大きくなると、前述したように予め型締条件設定部３３に入力されている型締力の上昇幅だけ型締力が大きくなるようにクロスヘッド位置を前進させる。このようにして、型締力の制御が繰り返し行われる。
【００２３】
溶融樹脂の射出充填が完了すると保圧工程に入る。保圧工程中は樹脂反力の変動が少ないため、図３に示すように保圧終了時付近の如く圧力制御は殆ど行われていない。
そして、この保圧工程の末期から冷却工程期間中（保圧終了直前まで）においては樹脂反力は徐々に小さくなっていく。従って、クロスヘッド位置を前述の樹脂反力が増大する期間中の最終位置に固定していると、樹脂反力（Ｆ３）が小さくなった分だけ実効型締力（Ｆ２）が小さくなる。従って、（Ｆ２−Ｆ１）の値は小さくなり、最終的にはゼロとなる。この状態では、樹脂反力が増大している時の最大型締力が負荷されていることになる。
冷却期間中に大きな型締力を負荷したい場合はこの時点で型締力の制御を中止すれば良い。一方、樹脂の収縮・固化に応じて型締力を小さくしたい場合には（Ｆ２−Ｆ１）を予め設定された許容値になるようにクロスヘッドを後退させる制御を行う。以下に、この場合の制御方法について説明する。
【００２４】
保圧工程の末期から冷却工程期間中における型締力の制御方法について説明する。この期間中においても型締力制御の技術思想は射出充填工程や保圧期間中の樹脂反力が大きくなる場合と同じである。即ち、実効型締力（Ｆ２）と現在のクロスヘッド位置に相当するドライサイクル時の型締力、即ち設定型締力（Ｆ１）との差を比較する。キャビティ内の樹脂の固化が進み体積収縮が起こるので、樹脂反力（Ｆ３）は次第に小さくなっていく。この為、実効型締力Ｆ２は樹脂反力（Ｆ３）分だけ小さくなる。従って、現状のクロスヘッド位置における（Ｆ２−Ｆ１）の値は小さくなり、更に樹脂の固化・収縮が進むとゼロになる。
実効型締力（Ｆ２）と設定型締力（Ｆ１）が同じになるということは、樹脂のない状態、即ちドライサイクルの状態であり、キャビティ内の樹脂に対して何ら力を負荷していないことになる。この状態では金型に大きな力を作用させるだけであり、何の効果もない。従って、金型寿命の延命、省エネの目的から冷却期間中の型締力制御を行うことになる。
【００２５】
前述の通り、実効型締力（Ｆ２）が小さくなるため、設定型締力（Ｆ１）も同じだけ小さくする必要がある。この為、クロスヘッド位置を後退させることにより、、設定型締力（Ｆ１）を小さくすることができる。（Ｆ２−Ｆ１）の許容値やクロスヘッド位置の移動量については樹脂反力の上昇時と同じ考え方である。但し、設定型締力が０トン以下となるようなクロスヘッド位置にしてしまうと金型と成形品の間に隙間が出来てしまうため冷却速度が低下する。このため設定型締力が０トン以下となった時点で制御を中止してそのままのクロスヘッド位置を保持してタイムアウト信号により型開きする
【００２６】
溶融樹脂の充填後期において、金型キャビティへの充填が完了した後も射出動作が継続されていると、パック圧が発生する。このため設定型締力の上昇速度が追いつけずにバリが発生することがある。この不具合を解消するために射出後半においては速度制御から圧力制御への切換を早めに行いパック圧の発生を抑制することが望ましい。又、保圧設定も１秒程度低圧の保圧を行ったあと通常の保圧条件に移行することが望ましい。但し、このような配慮は特に流動性の高い樹脂に対してのみ行えば良い。
【００２７】
以下に、比較例と実施例について説明する。
【比較例１】
投影面積約８５０ｃｍ2 、厚み３ｍｍの略箱型形状の金型を使用し、成形材料としてポリカーボネイト樹脂を使用し成形した。射出成形機としては最大型締力が４５０トン、サーボモータ／ボールネジ機構のトグル駆動装置を搭載した横形射出成形機を使用した。成形条件として、金型温度８５℃、射出ユニットのバレル設定温度３００℃、型締力４００トン、射出時間８秒、保圧時間５秒、保圧圧力４００ｋｇｆ／ｃｍ2 の設定で通常の成形を行った。この結果、成形品にはバリの発生はなかった。また、偏光板により残留応力を確認した結果、干渉縞の数は多数存在していた。
【００２８】
【実施例１】
比較例１と同じ金型、成形材料、金型温度、バレル設定温度で初期型締力を２００トンに設定し、実効型締力（Ｆ２）と設定型締力（Ｆ１）との差（Ｆ２−Ｆ１）が２０トンを超えると設定型締力が２０トンだけ大きくなるようなクロスヘッド位置にクロスヘッドを前進させる条件を設定した。射出時間、保圧時間、保圧圧力は比較例１と同じ条件で成形した。型締力の制御期間は射出と保圧初期とし、樹脂反力が減少する保圧後期および冷却期間中は型締力の制御は行わなかった。この結果、設定型締力の最終値は２８０トンとなった。この成形品はバリの発生もなく、また、偏光板により残留応力を確認した結果、干渉縞の数は比較例１の半分になっていた。
【００２９】
以上、本発明に従う構造とされたトグル式射出成形機の型締制御装置および型締制御方法の一実施例について詳述してきたが、これは文字通りの例示であって、本発明はかかる具体例に限定して解釈されるものではない。
例えば、トグル駆動機構として、サーボモータ／ボールネジ機構の代わりに油圧シリンダを採用することもできるし、型締力検出センサ取付位置として、タイバの代わりにトグルリンクを採用することも出来る。
その他、一々列挙はしないが、本発明は当業者の知識に基づいて種々なる変更、修正、改良等を加えた態様において実施され得るものであり、またそのような実施態様が、本発明の趣旨を逸脱しない限りにおいて、何れも本発明の範囲内に含まれるものであることは、言うまでもないところである。
【００３０】
【発明の効果】
以上説明した通り、本発明によれば、オペレータの熟練度に左右されないで必要最低限の型締力が自動的に負荷されるため、キャビティ内のガス抜けが良好であり、ＣＤ等薄物の成形であっても無理なく成形できる。従って、残留応力の少ない、変形のない成形品を効率的に得ることができる。特に、光学的な用途に使用される成形品には好適である。
【図面の簡単な説明】
【図１】本発明に係るトグル式射出成形機の型締力制御装置の構成図である。
【図２】本発明に係るクロスヘッド位置と実効型締力、樹脂反力等の説明図である。
【図３】本発明に係る実効型締力と設定型締力の制御状態の説明図である。
【図４】本発明に係る型締力制御のフローチャート図である
【符号の説明】
１ トグル式射出成形機の型締制御装置
２ タイバ
３ 固定盤
４ リンクハウジング
５ 可動盤
６ 固定金型
７ 可動金型
８ サーボモータ
１０ トグルリンク（トグル機構）
１１ ボールネジ（ボールネジ機構）
１２ クロスヘッド
１３ 型締力検出センサ
１４ クロスヘッド位置検出センサ
３０ 型締力検出部
３１ クロスヘッド位置検出部
３３ 型締条件設定部
３４ 型締制御部
３５ 記憶部
３６ 型締作動機構制御部
３７ 演算部
３８ 比較制御部
Ｆ０ 初期型締力
Ｆ１ 設定型締力
Ｆ２ 実効型締力
Ｆ３ 樹脂反力
Ｆ４ 型圧力
Ａ 金型タッチ点[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold clamping force control method and apparatus for an injection molding machine, and in particular, can efficiently mold a thin molded product at low pressure and efficiently produce a good quality molded product with little residual stress and deformation. The present invention relates to a mold clamping force control method and apparatus for an injection molding machine.
[0002]
[Prior art]
In conventional injection molding, a skilled operator predicts the mold clamping force empirically in consideration of molding conditions such as the size of the molded product and molding material, and determines the clamping force by trial and error by performing trial punching. It was. For this reason, highly skilled operators open the mold within a range where burrs do not occur during injection filling of the molten resin, and perform molding with a mold clamping force that is low enough to discharge gas generated in the cavity and from the molten resin. It was. In particular, when molding a thin product such as a CD disk, molding is performed at a low pressure as much as possible to prevent residual stress from remaining in the molded product and to prevent deformation of the molded product and optical properties such as birefringence of the molded product. The deterioration of quality was prevented.
[0003]
However, the minimum mold clamping force (described later) corresponding to the mold opening force (which is a force for opening the mold, hereinafter also referred to as the resin reaction force) that increases as the injection filling of the molten resin proceeds. Could not be loaded. That is, there has been no control method for changing the mold clamping force set before the start of the molding cycle in response to the resin reaction force that changes every moment during the molding cycle. Therefore, it is difficult to obtain a thin product such as a CD disk at an optically satisfactory quality level because a mold clamping force more than necessary is applied.
[0004]
On the other hand, since the setting of the clamping force as described above cannot be expected by a general operator, the residual stress of the molded product increases due to the excessive clamping force being applied, and the deformation and birefringence of the molded product increase. It was difficult to obtain a good product due to the increase in size. In addition, excessive mold clamping force is applied, so that the mold is worn out and much maintenance is required.
There is JP-A-8-276479 as a prior art that solves the above problems.
[0005]
In this prior art, a movable mold and a fixed mold of a disk substrate mold are respectively attached to a movable plate and a fixed plate of a molding machine, and the movable mold is 0 to 0 with respect to the fixed mold by a mold closing operation. When moving to a predetermined distance of 5 mm, injection of molten resin from the nozzle of the injection device into the cavity of the disk substrate mold is started, and the movable mold comes into contact with the fixed mold And the hydraulic pressure supplied to the clamping side of the clamping cylinder is adjusted so that the clamping force is maintained at a predetermined value corresponding to approximately 10 to 40% of the rated clamping force. After the process is completed, the hydraulic pressure supplied to the mold clamping side of the mold clamping cylinder is increased to perform one-stage or multiple-stage mold clamping pressure control, and the molten resin in the cavity is cooled with the rated mold clamping force. Techniques to do are disclosed.
[0006]
However, even in the above prior art, the degree of pressure reduction of the mold clamping force is not sufficient, and a mold clamping pressure exceeding the necessary minimum is loaded. In addition, the timing at which the mold clamping force corresponding to approximately 10 to 40% of the rated mold clamping force is applied and the relationship between the mold clamping force and the resin reaction force are not clear, and injection filling is performed after the mold clamping force is applied. Sometimes completed. In this case, there is a possibility that the outgassing becomes insufficient. Also, the resin reaction force becomes larger than the clamping force before the injection process is completed, and once the mold is closed and a small clamping force of 10 to 40% of the rated load is applied, the mold is reopened to generate burrs. There is also a fear.
[0007]
The minimum required mold clamping force described in paragraph 0003 is the injection process in which a slight gap is opened between the fixed mold and the movable mold to the extent that burrs are not generated even when the mold mating surface is opened. This is the mold clamping force necessary to maintain the inside constantly, and varies depending on the filling behavior of the resin. That is, since only a part of the mold cavity is filled with resin at the initial stage of injection filling, the force for opening the mold by the filled resin is small, and the resin reaction force increases as filling proceeds. .
[0008]
Further, air exists in the mold cavity, and in the injection molding in which the molten resin is filled at a high speed, this air needs to be quickly discharged out of the mold. In this case, if the fixed mold and the movable mold are tightened with a large force, there is no escape space for air, the air in the mold is adiabatically compressed and becomes high temperature, causing gas burn in the molded product and partly It enters into the molten resin and causes a molded product defect called void. In addition, if a gas vent passage is provided on the die mating surface to improve gas venting, the molten resin leaks from this portion, resulting in burrs and defective molding.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a mold clamping force control method and apparatus for an injection molding machine in which the necessary minimum mold clamping force is automatically applied without depending on the skill level of the operator, and to solve the above problems. .
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, in the present invention, in the first invention, the molten resin is injected into a mold cavity formed by closing both the movable mold and the fixed mold. In a mold clamping force control method of an injection molding machine using a toggle to inject and fill a mold, a mold clamping force applied to the mold during the mold clamping force holding period is detected by a mold clamping force detecting means. It was obtained by calculating the effective clamping force obtained by calculating the detected value, the crosshead position when the molds were matched in the dry cycle state, and the detected value obtained at that time. Based on the relationship with the set mold clamping force, the mold clamping force is controlled by controlling the crosshead position so that the mold clamping force value obtained by subtracting the set mold clamping force from the effective mold clamping force falls within a preset allowable value. During the period, the minimum required clamping force was applied between the molds.
[0011]
In the second invention, the crosshead position is set so that the effective mold clamping force is always larger than the set mold clamping force during injection filling of the molten resin in the first invention into the mold cavity and during the pressure holding period. It was decided to control.
Furthermore, in the third invention, the effective mold clamping force is always larger than the set mold clamping force during the pressure holding period and the cooling period after the molten resin in the first invention is injected and filled into the mold cavity. Thus, the crosshead position was controlled.
[0012]
Next, in the fourth invention, in order to obtain a molded product by closing both the movable mold and the fixed mold and injecting and filling the molten resin into the mold cavity formed between the molds. In a mold clamping force control device for an injection molding machine using a toggle, a mold clamping force detection unit for detecting a mold clamping force applied to the mold during a mold clamping force holding period by a mold clamping force detection sensor, and a dry cycle A storage unit that stores the relationship between the crosshead position when both molds are matched and the clamping force calculated based on the detected clamping force at that time, and the clamping force during the actual molding cycle A calculation unit that calculates the effective clamping force based on the detection value from the detection unit, a comparison control unit that compares the effective clamping force calculated by the calculation unit and the input initial clamping force, and a mold A signal from the crosshead position detector that detects the amount of movement of the crosshead from the touch point and a signal from the comparison controller Receiving a mold clamping control unit issues a command value of the clamping force to the mold clamping cylinder control unit, and the mold clamping operation mechanism control unit for longitudinal movement of the crosshead based on the information obtained by the mold clamping control unit, at least the initial type structure and a mold clamping condition setting unit for setting the rise / fall width of clamping force and allowable value of the initial clamping force or mold clamping force value obtained by subtracting the set clamping force than the effective clamping force and the clamping force It was.
[0013]
In the fifth invention, the mechanism for driving the toggle in the fourth invention is constituted by a servo motor and a ball screw mechanism.
[0014]
[Action]
According to the present invention, the actual clamping force applied to the mold during the clamping period (which is defined as the effective clamping force in the present invention) is the stress of the clamping force transmission member of the clamping device. It is calculated by measuring and calculating. In addition, molds are aligned in a state where molten resin is not injected (also referred to as a dry cycle), and the crosshead is advanced from this state to obtain the relationship between the crosshead position and the effective clamping force.
On the other hand, in the actual molding cycle, a force for opening the mold due to the filling pressure of the molten resin, that is, a resin reaction force is generated. This resin reaction force becomes larger as the injection filling proceeds, and thereafter, the resin reaction force becomes smaller as the cooling of the filled resin proceeds.
[0015]
This will be described below with reference to FIG. The effective clamping force obtained from the crosshead position from the so-called touch point A where the molds are in contact with each other during the dry cycle (a state where the clamping force is zero) and the stress of the clamping force transmission member From the relationship, a mold clamping force (F1: line segment CB) at the dry cycle corresponding to a certain crosshead position (point B) is obtained. On the other hand, the mold clamping force obtained from the stress of the mold clamping force transmitting member during the actual molding cycle at the crosshead position, that is, the effective mold clamping force (F2: line segment EG) is greater than F1 because it receives the resin reaction force. ing.
F2> F1 (1 set)
Further, the effective mold clamping force (F2) and the resin reaction force (F3: line segment EF) obtained from the stress of the mold clamping force transmitting member, the mold pressure (F4) acting between the fixed mold and the movable mold. : Line segment FG) is as follows.
F2-F3 = F4 (2 formulas)
When this F4 becomes negative, a gap is left in the mold. When this clearance becomes large, the molten resin leaks out of the cavity and burrs are generated. Generally, although it depends on the type of resin and molding conditions, it is generally said that burrs do not occur if this clearance is in the range of 0 to 0.2 mm.
[0016]
One of the technical ideas of the present invention is to make the mold pressure (F4) as small as possible to improve the gas escape in the mold and to reduce the mold pressure applied to the molten resin in the cavity as much as possible. By smoothing the flow of the molten resin in the cavity, residual stress remaining in the molded product is reduced, and deformation of the molded product is reduced.
In addition, by achieving the above technical idea by program control, even a less experienced operator can easily and efficiently produce a molded article having good optical quality with little residual stress.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. 1 to 4 relate to an embodiment of the present invention, FIG. 1 is a configuration diagram of a mold clamping force control device of a toggle type injection molding machine according to the present invention, and FIG. 2 is a crosshead position and effective mold clamping according to the present invention. FIG. 3 is an explanatory diagram of the control state of the effective mold clamping force and the set mold clamping force, and FIG. 4 is a flowchart of mold clamping force control.
[0018]
The configuration and operation of a toggle type injection molding machine used in the present invention will be described with reference to FIG. A mold clamping device 1 of an injection molding machine has a fixed platen 3 attached to a front end portion of a tie bar 2 and a link housing 4 attached to a rear end portion of a tie bar, and a toggle driving (mold clamping) servomotor 8 is attached to the link housing 4. It is fixed. By driving the crosshead 12 by the servo motor 8 and the ball screw mechanism 11, the movable platen 5 sliding on the tie bar 2 via the toggle link is moved away from the fixed platen 3 and this movable platen 5 A movable mold 7 is attached to the fixed platen 3, and a fixed mold 6 is attached to the stationary platen 3.
[0019]
A strain gauge is attached on the tie bar 2 as the mold clamping force detection sensor 13, and the detection signal is transmitted to the mold clamping force detection unit 30.
A linear sensor is used as the position detection sensor 14 of the crosshead 12, and the detection signal is transmitted to the crosshead position detection unit 31. In this embodiment, since the servo motor and the ball screw mechanism are employed as the toggle drive mechanism, the crosshead position can be calculated from the rotation angle of the servo motor.
[0020]
Next, the configuration and function of the mold clamping force control device will be described.
The initial mold clamping force and mold clamping speed, the tolerance between the effective mold clamping force and the set mold clamping force, the increase / decrease width of the mold clamping force, and the like are input to the mold clamping condition setting unit 33. These input values are transmitted to the mold clamping control unit 34. Before starting the molding cycle, the relationship data between the position (distance) of the crosshead from the mold alignment position and the mold clamping force (F1 = F2) is taken and stored in the storage unit 35 without injecting resin (dry cycle). Let
[0021]
Based on an initial mold clamping force (F0) input to the mold clamping condition setting unit 33, the mold clamping operation is performed based on a command from the mold clamping operation mechanism control unit 36 via the mold clamping control unit 34. When the mold clamping operation is completed, an injection control unit (not shown) issues a molten resin injection command and fills the mold cavity with the molten resin.
As the filling of the molten resin proceeds, a resin reaction force (F3) is generated, and the tie bar stress increases against the force to open the mold. The tie bar stress is detected by the mold clamping force detection unit 30 via the mold clamping force detection sensor 13, and the calculation unit 37 calculates and calculates the force (effective mold clamping force (F2)) applied to the tie bar. The calculated effective clamping force (F2) and the input initial clamping force (F0) are compared by the comparison control unit 38.
[0022]
When the value obtained by subtracting the initial mold clamping force (F0) from the effective mold clamping force (F2) is larger than the allowable value previously input to the mold clamping condition setting unit 33, the value is input to the mold clamping condition setting unit 33 in advance. The crosshead position is advanced so that the mold clamping force increases as much as the mold clamping force increases. As shown in FIG. 2, the relationship between the increase in mold clamping force and the amount of movement of the crosshead position (setting B) is as shown in FIG. 2. The data during the dry cycle collected before the start of the molding cycle, that is, the crosshead from the mold alignment position. Is calculated and calculated by the calculation unit 37 based on the relationship between the position (distance) and the clamping force. The mold clamping force calculated based on FIG. 2 at the position after the crosshead is moved becomes the set mold clamping force (F1) at the crosshead position.
The resin reaction force further increases as the molten resin fills, and the value obtained by subtracting the set clamping force (the value at the start of injection was the initial clamping force) from the effective clamping force is set in advance. When the value exceeds the allowable value input to the part 33, the crosshead position is advanced so that the mold clamping force is increased by the increase width of the mold clamping force previously input to the mold clamping condition setting part 33 as described above. . In this way, the mold clamping force is repeatedly controlled.
[0023]
When the injection filling of the molten resin is completed, the pressure holding process is started. During the pressure holding process, the resin reaction force hardly fluctuates, so that pressure control is hardly performed as in the vicinity of the pressure holding end as shown in FIG.
The resin reaction force gradually decreases from the end of the pressure-holding process to the period of the cooling process (until the end of pressure-holding). Accordingly, when the crosshead position is fixed at the final position during the period in which the resin reaction force increases, the effective mold clamping force (F2) decreases by the amount that the resin reaction force (F3) decreases. Therefore, the value of (F2-F1) becomes small and finally becomes zero. In this state, the maximum mold clamping force when the resin reaction force is increasing is loaded.
If a large mold clamping force is to be applied during the cooling period, the control of the mold clamping force may be stopped at this point. On the other hand, when it is desired to reduce the mold clamping force in accordance with the shrinkage / solidification of the resin, control is performed to retract the crosshead so that (F2-F1) becomes a preset allowable value. The control method in this case will be described below.
[0024]
A method for controlling the mold clamping force during the cooling process from the end of the pressure holding process will be described. Even during this period, the technical idea of mold clamping force control is the same as when the resin reaction force during the injection filling process and the pressure holding period is increased. That is, the difference between the effective mold clamping force (F2) and the mold clamping force in the dry cycle corresponding to the current crosshead position, that is, the set mold clamping force (F1) is compared. As the resin in the cavity solidifies and volume shrinkage occurs, the resin reaction force (F3) gradually decreases. Therefore, the effective mold clamping force F2 is reduced by the resin reaction force (F3). Therefore, the value of (F2-F1) at the current crosshead position becomes small, and becomes zero when the solidification / shrinkage of the resin further proceeds.
The fact that the effective clamping force (F2) and the set clamping force (F1) are the same means that there is no resin, that is, a dry cycle state, and no force is applied to the resin in the cavity. It will be. In this state, only a large force is applied to the mold, and there is no effect. Accordingly, mold clamping force control during the cooling period is performed for the purpose of extending the life of the mold and saving energy.
[0025]
As described above, since the effective mold clamping force (F2) is reduced, the set mold clamping force (F1) needs to be reduced by the same amount. Therefore, the set mold clamping force (F1) can be reduced by retreating the crosshead position. The allowable value of (F2-F1) and the amount of movement of the crosshead position are the same concept as when the resin reaction force is increased. However, if the crosshead position is set such that the set clamping force is 0 ton or less, a gap is formed between the mold and the molded product, and the cooling rate is reduced. For this reason, when the set mold clamping force becomes 0 ton or less, the control is stopped, the position of the crosshead is held as it is, and the mold is opened by the time-out signal.
If the injection operation is continued after the filling of the mold cavity is completed in the latter half of the filling of the molten resin, a pack pressure is generated. For this reason, the rising speed of the set clamping force may not catch up, and burrs may occur. In order to eliminate this problem, it is desirable to switch from speed control to pressure control early in the second half of injection to suppress the generation of pack pressure. Also, it is desirable that the holding pressure setting is shifted to the normal holding pressure condition after holding a low pressure for about 1 second. However, such consideration should be made only for a resin having particularly high fluidity.
[0027]
Below, a comparative example and an Example are demonstrated.
[Comparative Example 1]
An approximately box-shaped mold having a projected area of about 850 cm 2 and a thickness of 3 mm was used, and molding was performed using a polycarbonate resin as a molding material. As the injection molding machine, a horizontal injection molding machine with a maximum clamping force of 450 tons and a servo motor / ball screw mechanism toggle drive device was used. Molding conditions are as follows: mold temperature 85 ° C, injection unit barrel set temperature 300 ° C, mold clamping force 400 tons, injection time 8 seconds, holding pressure 5 seconds, holding pressure 400 kgf / cm 2 went. As a result, no burrs were generated in the molded product. Moreover, as a result of confirming the residual stress with the polarizing plate, there were many interference fringes.
[0028]
[Example 1]
The initial mold clamping force is set to 200 tons at the same mold, molding material, mold temperature, and barrel set temperature as in Comparative Example 1, and the difference (F2) between the effective mold clamping force (F2) and the set mold clamping force (F1) The condition for advancing the crosshead to the crosshead position was set such that the set clamping force increased by 20 tons when -F1) exceeded 20 tons. The injection time, holding time, and holding pressure were molded under the same conditions as in Comparative Example 1. The control period of the mold clamping force was in the initial stage of injection and pressure holding, and the mold clamping force was not controlled during the latter period of pressure holding during which the resin reaction force decreased and during the cooling period. As a result, the final value of the set clamping force was 280 tons. This molded product had no burrs, and the residual stress was confirmed by the polarizing plate. As a result, the number of interference fringes was half that of Comparative Example 1.
[0029]
The embodiment of the mold clamping control device and mold clamping control method of the toggle type injection molding machine having the structure according to the present invention has been described in detail above, but this is a literal example, and the present invention is such a specific example. It is not construed as limited to.
For example, a hydraulic cylinder can be employed as the toggle drive mechanism instead of the servo motor / ball screw mechanism, and a toggle link can be employed as the clamping force detection sensor mounting position instead of the tie bar.
In addition, although not enumerated one by one, the present invention can be carried out in a mode with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art, and such a mode is the gist of the present invention. It goes without saying that all are included in the scope of the present invention without departing from the scope of the present invention.
[0030]
【The invention's effect】
As described above, according to the present invention, the minimum required clamping force is automatically applied without being influenced by the skill level of the operator, so that the gas escape in the cavity is good and the molding of a thin object such as a CD is performed. However, it can be formed without difficulty. Therefore, it is possible to efficiently obtain a molded product with little residual stress and without deformation. In particular, it is suitable for molded articles used for optical applications.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a mold clamping force control device of a toggle type injection molding machine according to the present invention.
FIG. 2 is an explanatory diagram of the crosshead position, effective mold clamping force, resin reaction force, and the like according to the present invention.
FIG. 3 is an explanatory diagram of a control state of an effective mold clamping force and a set mold clamping force according to the present invention.
FIG. 4 is a flowchart of mold clamping force control according to the present invention.
DESCRIPTION OF SYMBOLS 1 Clamping control apparatus 2 of a toggle type injection molding machine 2 Tie bar 3 Fixed platen 4 Link housing 5 Movable platen 6 Fixed die 7 Movable die 8 Servo motor 10 Toggle link (toggle mechanism)
11 Ball screw (ball screw mechanism)
12 Crosshead 13 Mold clamping force detection sensor 14 Crosshead position detection sensor 30 Mold clamping force detection unit 31 Crosshead position detection unit 33 Mold clamping condition setting unit 34 Mold clamping control unit 35 Storage unit 36 Mold clamping operation mechanism control unit 37 Part 38 Comparison control part F0 Initial mold clamping force F1 Set mold clamping force F2 Effective mold clamping force F3 Resin reaction force F4 Mold pressure A Mold touch point

Claims (5)

可動金型と固定金型の両金型を閉じて該両金型間に形成される金型キャビティ内へ溶融樹脂を射出充填して成形品を得るためにトグルを用いた射出成形機の型締力制御方法であって、型締力保持期間中に該金型に付与された型締力を型締力検出手段により検出された検出値を演算して得られた実効型締力と、ドライサイクル状態下における該両金型の型合わせ状態時のクロスヘッド位置とその時得られた検出値を演算して得られた設定型締力との関係に基いて、前記実効型締力から前記設定型締力を差引いた型締力値が予め設定した許容値に入るようにクロスヘッド位置を制御することにより、型締期間中に該両金型間に金型合わせ面が開いてもバリが発生しない程度の型締力を付与するように制御することを特徴とする射出成形機の型締力制御方法。A mold for an injection molding machine that uses a toggle to close a movable mold and a fixed mold and inject a molten resin into a mold cavity formed between the molds to obtain a molded product. A clamping force control method, an effective clamping force obtained by calculating a detection value detected by a clamping force detection means for a clamping force applied to the mold during a clamping force holding period; Based on the relationship between the crosshead position in the mold matching state of both molds under the dry cycle state and the set mold clamping force obtained by calculating the detection value obtained at that time, the effective mold clamping force By controlling the crosshead position so that the mold clamping force value obtained by subtracting the set mold clamping force falls within the preset allowable value, even if the mold mating surface opens between the molds during the mold clamping period, clamping force of the injection molding machine, characterized in that but controlled so as to impart a clamping force so as not to occur Your way. 溶融樹脂を金型キャビティ内に射出充填中および保圧期間も常に前記実効型締力が前記設定型締力よりも大きくなるようにクロスヘッド位置を制御するようにしたことを特徴とする請求項１記載の射出成形機の型締力制御方法。The crosshead position is controlled so that the effective clamping force is always greater than the set clamping force during injection filling of molten resin into a mold cavity and during a pressure holding period. 2. A mold clamping force control method for an injection molding machine according to 1. 溶融樹脂を金型キャビティ内に射出充填した後の保圧期間中および冷却期間も常に前記実効型締力が前記設定型締力よりも大きくなるようにクロスヘッド位置を制御するようにしたことを特徴とする請求項１記載の射出成形機の型締力制御方法。The crosshead position is controlled so that the effective mold clamping force is always larger than the set mold clamping force during the pressure holding period and the cooling period after the molten resin is injected into the mold cavity. 2. The mold clamping force control method for an injection molding machine according to claim 1, wherein 可動金型と固定金型の両金型を閉じて該両金型間に形成される金型キャビティ内へ溶融樹脂を射出充填して成形品を得るためにトグルを用いた射出成形機の型締力制御装置であって、型締力保持期間中に該金型に付与された型締力を型締力検出センサにより検出する型締力検出部と、ドライサイクル状態下で両金型の型合わせをした際のクロスヘッド位置とその時の型締力検出値に基いて演算される型締力の関係を記憶する記憶部と、実成形サイクル中に型締力検出部よりの検出値に基いて実効型締力を演算する演算部と、演算部で演算された実効型締力と入力されている初期型締力とを比較する比較制御部と、金型タッチ点よりのクロスヘッドの移動量を検出するクロスヘッド位置検出部と、比較制御部からの信号を受けて型締シリンダ制御部に型締力の指令値を発する型締制御部と、型締制御部で得られた情報に基づきクロスヘッドを前後動させる型締作動機構制御部と、少なくとも初期型締力と実効型締力より初期型締力又は設定型締力を差し引いた型締力値の許容値と型締力の上昇幅／下降幅とを設定する型締条件設定部とから構成される射出成形機の型締力制御装置。A mold for an injection molding machine that uses a toggle to close a movable mold and a fixed mold and inject a molten resin into a mold cavity formed between the molds to obtain a molded product. A clamping force control device, which includes a clamping force detection unit that detects a clamping force applied to the mold during a clamping force holding period by a clamping force detection sensor, and both molds in a dry cycle state. A memory unit that stores the relationship between the crosshead position when the molds are aligned and the clamping force detection value calculated at that time, and a detection value from the clamping force detection unit during the actual molding cycle Based on the calculation unit that calculates the effective clamping force, the comparison control unit that compares the effective clamping force calculated by the calculation unit and the input initial clamping force, and the crosshead from the mold touch point In response to signals from the crosshead position detection unit that detects the amount of movement and the comparison control unit, the clamping cylinder control A mold clamping control unit issues a command value of the clamping force to the part, and the mold clamping operation mechanism control unit for longitudinal movement of the crosshead based on the information obtained by the mold clamping control unit, at least the initial clamping force and the effective clamping Die of an injection molding machine comprising an allowable value of a mold clamping force value obtained by subtracting an initial mold clamping force or a set mold clamping force from a force, and a mold clamping condition setting unit for setting an increase / decrease width of the mold clamping force Tightening force control device. トグルを駆動する機構がサーボモータとボールネジ機構からなることを特徴とする請求項４記載の射出成形機の型締力制御装置。5. The mold clamping force control device for an injection molding machine according to claim 4, wherein the mechanism for driving the toggle comprises a servo motor and a ball screw mechanism.
JP33759299A 1999-11-29 1999-11-29 Method and apparatus for controlling mold clamping force of injection molding machine Expired - Fee Related JP3918386B2 (en)

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AT521442B1 (en) * 2018-07-12 2021-07-15 Engel Austria Gmbh Dynamic adjustment of the clamping force
CN110640983B (en) * 2019-10-29 2023-12-29 宁波创基机械有限公司 Automatic adjusting device and method for mold locking force of injection molding machine
CN112976519B (en) * 2021-02-05 2022-06-28 伯乐智能装备股份有限公司 Self-adjusting method for clamping force of two-plate machine

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