JP2004188798A

JP2004188798A - Metering method for injection molding machine

Info

Publication number: JP2004188798A
Application number: JP2002359781A
Authority: JP
Inventors: Morihisa Igarashi; 盛久五十嵐
Original assignee: Niigata Machine Techno Co Ltd
Current assignee: Niigata Machine Techno Co Ltd
Priority date: 2002-12-11
Filing date: 2002-12-11
Publication date: 2004-07-08
Anticipated expiration: 2022-12-11
Also published as: JP4114139B2

Abstract

<P>PROBLEM TO BE SOLVED: To surely meter a molten resin by preventing the sagging phenomenon of the molten resin having extremely low or high viscosity when metering is done without making an injection nozzle touch a mold, and to properly perform the warning and stoppage of abnormal metering. <P>SOLUTION: A standard retreat speed corresponding to the set rotational speed of an injection screw 3 determined on the basis of the plastication capacity of an electromotive injection molding machine A is set to a control device 10. The retreat speed of the injection screw 3 is detected by an absolute encoder (position detecting means) 9a at metering and, when the detection value is above the standard retreat speed corresponding to the set rotational speed of the injection screw 3, a warning message is issued, and metering operation is stopped. When the detection value is below the standard retreat speed, the set value of the back pressure of the injection screw 3 is changed automatically by a controller 14. When the number of times of the change reaches the preset number of times, the metering operation is stopped. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、射出成形機の射出装置における加熱筒内の先端部に溶融樹脂を供給して計量する計量方法に関するものである。
【０００２】
【従来の技術】
従来、射出成形機で金型にノズルタッチをせずに計量を行う場合は、射出スクリュを最低に設定した背圧を付加した状態で回転させ、加熱筒の基端部に導入される樹脂材料を可塑化して加熱筒の先端部の樹脂溜まり部に溶融樹脂を供給し、この溶融樹脂の樹脂圧で後退する射出スクリュが後退端の計量完了位置に達すると、前記射出スクリュの回転を停止し、必要に応じて前記計量完了位置から更に所定距離だけ後退して樹脂溜まり部の樹脂圧を低下させるサックバックを自動的に行っている。
しかし、このように、金型にノズルタッチをせずに計量を行う射出成形機における計量方法では、超低粘度樹脂の場合には、機械に定められた最低の設定背圧でも、開放されている射出ノズルの開口部から溶融樹脂が流出する所謂鼻たれ現象が生じるために、前記射出スクリュを計量完了位置まで後退させて計量を完了させることができない不都合が起こる。また、高粘度樹脂の場合には、加熱筒を加熱するヒータの温度設定を低くすると、前記最低の設定背圧では、樹脂材料と加熱筒との摩擦が大きく、樹脂材料が可塑化しない状態で射出スクリュが計量完了位置まで後退してしまい、計量動作が正常に行えないという不具合が発生する問題がある。
【０００３】
そこで、常に、正常な計量動作を確保し、樹脂材料の可塑化不足による成形不良の発生を防止するため、予め、計量時における射出スクリュの後退速度に対する上、下限値を設定すると共に、計量中に射出スクリュの後退速度を検出し、該後退速度が前記上、下限値を外れた際に、射出スクリュの回転を設定時間だけ停止させ、その後射出スクリュを再開転させ、あるいは、予め、計量時間に対する上、下限値を設定すると共に、計量時に計量時間を検出し、該計量時間が前記上、下限値を外れた際に、射出スクリュの回転を設定時間だけ停止させ、その後射出スクリュを再回転させることにより目標の計量位置まで後退させて計量を終了させる計量方法が提案されている（例えば、特許文献１参照）。
【０００４】
【特許文献１】
特開平１０−２４４６８号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、上記提案の計量方法では、成形の中断を起こさせないことを前提にしており、所定条件の計量動作を繰り返すことによって樹脂材料の可塑化が進み、溶融樹脂の樹脂圧で射出スクリュが計量完了位置に後退して計量が正常に終了する場合に適用し得るものであるが、金型に射出ノズルをノズルタッチをさせずに、超低粘度樹脂や高粘度樹脂を計量する場合に、射出ノズルを計量完了位置まで後退移動させることができない異常な状態が生じた際、その異常状態を検出して、それに対応して適切に計量動作の継続、または停止を行わせることができない問題点がある。
【０００６】
本発明は、上記事情に鑑みてなされたものであって、金型に射出ノズルをノズルタッチさせないで計量を行う場合、超底粘度樹脂や高粘度樹脂であっても、溶融樹脂の鼻たれ現象を防止して溶融樹脂の計量を確実に行わせ、樹脂材料の非可塑化現象等による計量不可の異常時には、異常計量動作の警告、停止を適切に行える射出成形機の計量方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明は、前記課題を解決するために、以下の点を特徴としている。
すなわち、請求項１に係る射出成形機の計量方法は、加熱筒の射出ノズルを金型に接触させない状態で、可塑化スクリュを回転させて樹脂材料を可塑化して前記加熱筒の樹脂溜まり部内に溶融樹脂を供給し、該溶融樹脂に所定設定値の背圧を付加しながら加熱筒内を後退する射出部材の後退位置にもとづいて前記樹脂溜まり部内の溶融樹脂を計量する射出成形機の計量方法において、予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を上まわった場合に、警告メッセージの発生および計量動作の停止の少なくとも一方を行うことを特徴としている。
【０００８】
請求項２に係る射出成形機の計量方法は、加熱筒の射出ノズルを金型に接触させない状態で、可塑化スクリュを回転させて樹脂材料を可塑化して前記加熱筒の樹脂溜まり部内に溶融樹脂を供給し、該溶融樹脂に所定設定値の背圧を付加しながら加熱筒内を後退する射出部材の後退位置にもとづいて前記樹脂溜まり部内の溶融樹脂を計量する射出成形機の計量方法において、予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を下まわった場合に、前記射出部材の背圧の設定値を自動的に変更することを特徴としている。
【０００９】
請求項３に係る射出成形機の計量方法は、請求項２に記載の計量方法において、前記射出部材の背圧の設定値を変更する変更回数が予め設定した回数になったとき、計量動作を停止させることを特徴としている。
【００１０】
請求項４に係る射出成形機の計量方法は、加熱筒の射出ノズルを金型に接触させない状態で、可塑化スクリュを回転させて樹脂材料を可塑化して前記加熱筒の樹脂溜まり部内に溶融樹脂を供給し、該溶融樹脂に所定設定値の背圧を付加しながら加熱筒内を後退する射出部材の後退位置にもとづいて前記樹脂溜まり部内の溶融樹脂を計量する射出成形機の計量方法において、予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を下まわった場合に、前記射出部材を強制的に計量完了位置に後退させた後に、前記射出部材の背圧を監視しながら可塑化スクリュを回転させ、該背圧が前記設定値になったときに計量動作を停止させることを特徴としている。
【００１１】
【発明の実施の形態】
以下、本発明に係る射出成形機の計量方法を実施する計量装置について図１を参照して説明する。図１において、１は電動式射出成形機（射出成形機）Ａにおける計量装置である。前記計量装置１は、加熱筒２と、該加熱筒２の内部に軸方向に移動自在にかつ周方向に回転自在に挿入された射出スクリュ（可塑化スクリュ、射出部材）３と、可動台４に固定されており、前記射出スクリュ３の基端部と連結されて該射出スクリュ３を回転させるスクリュ回転用電動サーボモータ（スクリュ回転モータ）５と、前記可動台４に設けたナット６にねじ軸７を螺合させてなるねじ機構８の該ねじ軸７に連結されて可動台４を図１で左右に移動させ、前記射出スクリュ３を軸方向に前後進移動させるスクリュ前後進用電動サーボモータ（射出駆動手段）９と、前記スクリュ回転用電動サーボモータ５と前記スクリュ前後進用電動サーボモータ９を作動させる制御装置１０とを備えている。
【００１２】
そして、前記計量装置１は、電動射出成形機Ａの固定盤１１に固定した固定金型Ｋ１と可動盤１２に固定した可動金型Ｋ２とが当接されて型締めされ状態の金型Ｋに、前記加熱筒２の先端の射出ノズル２ａが接触しない（ノズルタッチをしない）状態で、前記スクリュ回転用電動サーボモータ５を回転させることにより、前記加熱筒２の基端部側のホッパ２ｂから加熱筒２内に導入される樹脂材料が可塑化され、溶融樹脂が加熱筒２の先端部の樹脂溜まり部２ｃ内に供給される。その際、スクリュ前後進用電動サーボモータ９を回転させることにより、前記ねじ機構８を介して可動台４が移動され、前記樹脂溜まり部２ｃ内に供給される溶融樹脂に対し後退移動する射出スクリュ３を介して背圧が付加され、該射出スクリュ３がその後退端の計量完了位置に到達して樹脂溜まり部２ｃ内への溶融樹脂の計量が完了されるようになっている。
【００１３】
なお、前記スクリュ回転用電動サーボモータ５にはインクレメントエンコーダ（回転速度検出手段）５ａが設けられ、また、前記スクリュ前後進用電動サーボモータ９にはアブソリュートエンコーダ（位置検出手段）９ａが設けられ、さらに、射出スクリュ３の基端部とスクリュ回転用電動サーボモータ５との連結部または前記可動台４に対する前記ナット６の装着部等には、射出スクリュ１４に作用する押圧力（荷重）を前記計量される溶融樹脂の背圧として検出する圧力センサー（圧力検出手段）１３が設けられている。前記圧力センサー１３は、前記樹脂溜まり部２ｃ内の溶融樹脂を直接に検出するものであってもよい。
【００１４】
また、前記制御装置１０は、前記計量装置１を含む電動射出成形機Ａの全体の動作を制御するコントローラ（動作制御手段）１４と、各種の指示項目や設定数値を入力し、入力された設定値に基づいて所要の演算処理等を行い、かつ各種データを表示する入力処理手段１５と、サーボアンプを有し、前記コントローラ１４からの動作指令にもとづいて動作して前記スクリュ回転用電動サーボモータ５を作動させると共に、前記インクレメントエンコーダ５ａで検出されるスクリュ回転速度信号（可塑化スクリュ回転速度信号）ｆを前記コントローラ１４に供給するスクリュ回転制御駆動装置１６と、サーボアンプを有し、前記コントローラ１４からの動作指令にもとづいて動作して前記スクリュ前後進用電動サーボモータ９を作動させると共に、前記アブソリュートエンコーダ９ａで検出されるスクリュ位置信号（射出部材位置信号）ｐと前記圧力センサー１１で検出される圧力信号ｋとを前記コントローラ１４に供給するスクリュ前後進制御駆動装置１７とを備えている。
【００１５】
なお、前記スクリュ回転制御駆動装置１６は、前記インクレメントエンコーダ５ａで検出されるスクリュ回転速度信号ｆにもとづいて、前記スクリュ回転用電動サーボモータ５の回転速度、すなわち射出スクリュ３の回転速度をフィードバック制御するようになっている。また、前記スクリュ前後進制御駆動装置１７は、前記アブソリュートエンコーダ９ａで検出されるスクリュ位置信号ｐと圧力センサー１３で検出される圧力信号ｋにもとづいて、スクリュ前後進用電動サーボモータ９の回転量（回転位置）と回転力（駆動トルク）、すなわち、射出スクリュ３の前後進位置、前後進速度および射出圧、背圧をフィードバック制御するようになっている。
【００１６】
前記入力処理手段１５は、前記電動射出成形機Ａを操作するための各種操作スイッチと、前記射出スクリュ３の前後進の移動速度を設定する速度設定器と、射出スクリュ３に作用する射出圧、背圧を設定する圧力設定器と、射出スクリュ３の前後進移動速度の切換位置、溶融樹脂の計量完了時における後退端位置（計量完了位置）等を設定する位置設定器と、前記射出スクリュ３の回転速度を設定する回転速度設定器と、射出スクリュ３の背圧を変更する回転の上限値を設定する背圧変更回数設定器と、機械の要目や成形に使用する樹脂材料の特性値を入力する要目設定器と、各種データを表示し、計量装置１の異常動作を機械のオペレータに警報、警告メッセージ等によって知らせる警告を発生する表示器と、前記要目設定器で入力された機械の各種要目に関する指示データと前記回転速度設定器に設定された計量時の射出スクリュ３の回転速度設定値とから、計量時の射出スクリュ３の標準後退速度等を演算する演算部とを備えている。
【００１７】
前記コントローラ１４は、前記電動射出成形機Ａの全体の動作を制御するシーケンスプログラム、前記入力処理手段１３において前記各設定器で設定された各種設定値（電動射出成形機Ａの成形条件）や前記演算部での演算によって得られた標準後退速度等を記憶するメモリと、該メモリに記憶されている設定値や前記インクレメントエンコーダ５ａ、アブソリュートエンコーダ９ａおよび圧力センサー１３の検出値にもとづいて、所要の演算、比較処理等を行って電動射出成形機１を動作させるための種々の制御データを作成し、該制御データを前記スクリュ回転制御駆動装置１６とスクリュ前後進御駆動装置１７に出力すると共に、前記入力処理手段１５の表示器に所要の表示項目を出力する動作制御手段とを備えている。
【００１８】
次に、前記構成の電動射出成形機Ａにおける計量装置１の作用と共に、該計量装置１による溶融樹脂の計量方法について、図２、図３をも参照して説明する。前記電動射出成形機Ａによる成形作業を開始するに先立ち、使用する電動射出成形機Ａの最大可塑化能力Ｃｈｍａｘ（ｋｇ／ｈ）、計量時の射出スクリュ３の最高回転数Ｒｍａｘ（ｍｉｎ^−１）、射出スクリュ３の直径Ｄ（ｃｍ）、成形に使用する樹脂材料の密度ρ（ｋｇ／ｌ）等を前記入力処理手段１５の要目設定器に入力すると共に、計量時の射出スクリュ３の設定回転速度Ｒｓｖ（ｍｉｎ^−１）を前記入力処理手段１５の回転速度設定器に入力すると共に、前記入力処理手段１５の位置設定器、圧力設定器および背圧変更回数設定器に、それぞれ、射出スクリュ３の計量完了位置、計量時の背圧および該背圧の設定値の上限変更回数を入力設定し、その他の設定器にも所要のデータを入力設定する（ステップＳ１）。前記最大可塑化能力Ｃｈｍａｘは、実験または前記加熱筒２、射出スクリュ３等に関する設計数値にもとづいて計算により求めることができる。
【００１９】
そして、前記入力処理手段１５においては、前記要目設定器に入力された各要目Ｃｈｍａｘ、Ｒｍａｘ、Ｄ、ρのもとづいて、演算部で次の演算式によって射出スクリュ３の計量時における設定回転速度に対応する標準後退速度Ｖｒが計算されると共に、他の各設定器に入力された設定値にもとづいて、コントローラ１４において使用する比較データが作成され（ステップＳ２）、それらの標準後退速度Ｖｒと比較データが前記コントローラ１４のメモリに記憶されると共に、各設定器で設定された設定値のうちで所要のものが選択されて入力処理手段１５の表示器に表示される。
【００２０】
【数１】

【００２１】
なお、前記入力処理手段１５の表示器には、計量装置１の計量動作時に、前記インクレメントエンコーダ５ａ、アブソリュートエンコーダ９ａおよび圧力センサー１３によって検出されたスクリュ回転速度信号ｆ、スクリュ位置信号ｐおよび圧力信号ｋにもとづいて、前記射出スクリュ３の回転速度、前後進移動速度と前後進移動位置、および背圧の各現在値等が表示される（ステップＳ３）。
【００２２】
前記入力処理手段１５における設定作業が終了すると、入力処理手段１５の操作スイッチを操作して電動射出成形機Ａの計量装置１による成形動作を開始させる。前記成形動作が開始されると、前記制御装置１０のコントローラ１４のメモリに記憶されているシーケンスプログラムに従って成形動作が実行され、コントローラ１４の指令によりスクリュ回転制御駆動装置１６とスクリュ前後進制御駆動装置１７を介して前記スクリュ回転用電動サーボモータ５とスクリュ前後進用電動サーボモータ９がそれぞれ回転されて、射出スクリュ３とねじ軸７がそれぞれ回転される。前記射出スクリュ３の回転によってホッパ２ｂから加熱筒２内に導入された樹脂材料が可塑化して溶融され、加熱筒２の樹脂溜まり部２ｃ内に供給されて計量される計量動作が開始される（ステップＳ４）。このとき、該樹脂溜まり部２ｃ内に供給される溶融樹脂の樹脂で押圧されて後退される射出スクリュ３に、前記ねじ軸１７の回転でねじ機構２２によって移動される可動台４と前記スクリュ回転用電動サーボモータ５とを介して押圧力を加えることにより、前記樹脂溜まり部２ｃ内の溶融樹脂に前記入力処理手段１４の圧力設定器で設定された所定の背圧が付加される。
【００２３】
前記計量動作中は、射出スクリュ３の後退移動位置が前記アブソリュートエンコーダ９ａで検出され、そのスクリュ位置信号ｐがスクリュ前後進制御駆動装置１７を経て前記コントローラ１４に送られ、該コントローラ１４において前記入力処理手段１５で設定された計量完了位置に前記射出スクリュ３が到達したか否かが比較、判断され（ステップＳ５）、射出スクリュ３が計量完了位置に到達した場合は、所定設定値の背圧で加熱筒２の樹脂溜まり部２ｃ内に溶融樹脂が正常に計量されたものとして、スクリュ回転制御駆動装置１６とスクリュ前後進制御駆動装置１７からの指令信号ｉ１，ｉ２で前記スクリュ回転用電動サーボモータ５とスクリュ前後進用電動サーボモータ９が停止されることにより、射出スクリュ３の回転と後退移動が停止して計量動作が停止される（ステップＳ６）。
【００２４】
前記ステップＳ５において、前記射出スクリュ３が設定された計量完了位置に到達しない場合は、前記アブソリュートエンコーダ９ａからのスクリュ位置信号ｐにもとづいてスクリュ前後進制御駆動装置１７で演算した射出スクリュ３の後退速度の現在値が、コントローラ１４において前記入力処理手段１５で演算してコントローラ１４のメモリに記憶されている標準後退速度Ｖｒの設定値と比較され（ステップＳ７）、その比較結果において、前記後退速度の現在値が標準後退速度Ｖｒの設定値より著しく上まわったと判断された場合（ステップＳ８）は、前記入力処理手段１５の表示器に可塑化エラーの警報を発生させ、または警告メッセージを表示する（ステップＳ９）と共に、計量動作が停止される（ステップＳ６）。この場合は、樹脂材料が高粘度樹脂であって、射出スクリュ３の設定背圧や加熱筒２の設定温度では、樹脂と加熱筒２の内壁との摩擦が大きい等の要因により、十分に樹脂の可塑化が進まないか可塑化が行われない状態で射出スクリュ３が早く後退し、計量動作が異常に行われたものと判断することができる。そこで、警告メッセージには、オペレータが独自の経験から定めた適正な計量条件を設定することや加熱筒２の設定加熱温度を上げることを求める案内を含めることができる。
【００２５】
前記ステップＳ７における比較結果において、前記射出スクリュ３の後退速度の現在値が標準後退速度Ｖｒの設定値より著しく下まわっていると判断された場合（ステップＳ１０）は、前記コントローラ１４が、前記入力処理手段１５の圧力設定器で設定した背圧設定値を、前記圧力センサー１３で検出される背圧の現在値に僅少な圧力値を加算または減算して得た圧力値に置き換えて設定背圧値を下げる変更を行い（ステップＳ１１）、その背圧設定値の変更回数が前記入力処理手段１４の背圧変更回数設定器で設定した設定変更回数に到達したか否かが判断され（ステップＳ１２）、変更回数が設定変更回数に到達しないときは、変更された背圧設定値で射出スクリュ３の回転が継続され、前記ステップＳ５に戻ってステップＳ５からステップＳ１２までの動作が繰り返される。
【００２６】
そして、前記ステップＳ１２において背圧設定値の変更回数が設定変更回数に到達したときは、ステップＳ６に移って計量動作が停止される。その際、入力処理手段１５の表示器にステップＳ９におけると同様に警告メッセージを発生させてもよい。この場合は、樹脂材料が低粘度樹脂であって、繰り返し背圧設定値を下げる変更を行っても、溶融樹脂が射出ノズル２ａから外部へ漏れ出てしまい、射出スクリュ３が計量完了位置に到達しないで溶融樹脂の計量ができない異常な状態が生じていると判断される。また、前記ステップＳ１２で、設定変更回数に到達しない場合、背圧設定値を変更したことにより、その変更した背圧設定値による計量動作を行った結果、ステップＳ５で射出スクリュ３が設定された計量完了位置に到達したときは、計量が正常に行われたものとしてステップＳ６に進んで計量動作が停止される。
さらに、前記ステップＳ７における比較結果において、前記射出スクリュ３の後退速度の現在値が標準後退速度Ｖｒの設定値と略等しいと判断された場合（ステップＳ１３）は、前記ステップＳ５に戻って射出スクリュ３の後退位置が入力処理手段１５の位置設定器で設定された計量完了位置に到達したことを確認された後に、ステップＳ６に進んで溶融樹脂の計量が前記入力処理手段１４で設定した背圧設定値で正常に行われたものとして計量動作が停止される。
【００２７】
前記ステップＳ７における比較結果において、前記射出スクリュ３の後退速度の現在値が標準後退速度Ｖｒの設定値より著しく下まわっていると判断された場合（ステップＳ１０）は、図３に示すように、前記計量方法とは別の計量方法を行うことができる。
すなわち、前記後退速度の現在値が標準後退速度Ｖｒの設定値より著しく下まわっていると判断されると、コントローラ１４が射出スクリュ３を前記標準後退速度を、例えば、その１／２の速度に設定して前記スクリュ前後進制御駆動装置１７を動作させることにより、前記入力処理手段１４で設定した背圧設定値に関係なく、射出スクリュ３が強制的に後退され（ステップＳ１４）、射出スクリュ３が計量完了位置に到達したときに（ステップＳ１５）、前記射出スクリュ３が設定された回転速度で回転が開始される（ステップＳ１６）。その射出スクリュ３の回転中は、前記圧力センサー１３からの圧力信号ｋにより背圧の実測値がコントローラ１４で監視されており、該背圧の実測値が、前記入力処理手段１５の圧力設定器で設定した背圧設定値に到達するまで射出スクリュ３が回転されて、到達したことが確認されると（ステップＳ１７）、溶融樹脂の計量が正常に行われたものとして計量動作が停止される（ステップＳ６）。
【００２８】
前記実施の形態に係る射出成形機の計量方法によれば、射出スクリュ３を金型に接触させない状態で計量を行う計量方法において、予め、電動射出成形機Ａの可塑化能力にもとづいて定めた射出スクリュ３の設定回転速度に対応する標準後退速度Ｖｒを設定しておき、前記射出スクリュ３を所定の設定回転速度Ｒｓｖで回転させて計量する時に、射出スクリュ３の後退速度をアブソリュートエンコーダ９ａで検出して、その検出値が前記射出スクリュ３の所定の設定回転速度Ｒｓｖに対応する標準後退速度Ｖｒを上まわった場合に、入力処理手段１５の表示器に警告メッセージを発生させると共に計量動作を停止させるようにしたので、樹脂材料が高粘度樹脂であって、射出スクリュ３の設定背圧や加熱筒２の設定温度では、樹脂と加熱筒２の内壁との摩擦が大きい等の要因により、十分に樹脂の可塑化が進まないか可塑化が行われない状態が生じた場合には、その異常状態をいち早く的確に知ることができて事後の対応処理を適切に行うことができると共に、異常状態で計量動作が無理に継続して機械に故障が発生するのを確実に防止することができる。
【００２９】
また、前記射出スクリュ３を所定の設定回転速度Ｒｓｖで回転させて計量する時に、射出スクリュ３の後退速度の検出値が前記射出スクリュ３の所定の設定回転速度Ｒｓｖに対応する標準後退速度Ｖｒを下まわった場合に、前記射出スクリュ３の背圧の設定値を自動的に変更すると共に、その変更回数が予め設定した回数になったとき、計量動作を停止させるようにしたので、溶融樹脂が射出ノズル２ａから外部へ漏れ出てしまう恐れがある低粘度樹脂の場合であっても、適時に射出スクリュ３の背圧設定値を変更することによって、その後退移動を促進させ、射出スクリュ３をその計量完了位置に到達させて溶融樹脂の計量を確実に行わせることができる。また、射出スクリュ３の背圧設定値を繰り返し変更しても、計量が確実に行われない異常状態のときは、不要に計量動作が継続するのを確実に防止することができる。
さらに、前記射出スクリュ３を所定の設定回転速度Ｒｓｖで回転させて計量する時に、射出スクリュ３の後退速度の検出値が前記射出スクリュ３の所定の設定回転速度Ｒｓｖに対応する標準後退速度Ｖｒを下まわった場合に、前記射出スクリュ３を強制的に計量完了位置に後退させた後に、前記射出スクリュ３の背圧を監視しながら射出スクリュ３を回転させ、該背圧が前記設定値になったときに計量動作を停止させるようにすると、加熱筒２の樹脂溜まり部２ｃ内の圧力が減圧され、樹脂溜まり部２ｃ内の溶融樹脂が射出スクリュ３のスクリュヘッド側への流動が促進され、超低粘度樹脂であっても、射出ノズル２ａからの鼻たれ現象を効果的に防止しながら確実に溶融樹脂の計量を行うことができる。
【００３０】
なお、前記実施の形態は、前記加熱筒２内に挿入した射出スクリュ３を、スクリュ回転用電動サーボモータ５で回転させると共に、スクリュ前後進用電動サーボモータ９の回転をねじ軸７にナット６を螺合させたねじ機構８を介して直線運動に変換して前後進移動させ、射出スクリュ３の回転速度、背圧、移動速度、移動位置を、それぞれ、スクリュ回転用電動サーボモータ５のインクレメントエンコーダ５ａ、圧力センサー１３、スクリュ前後進用サーボモータ１９のアブソリュートエンコーダ９ａで検出して射出スクリュ３の動作を制御するようにした電動式射出成形機Ａにおいて本発明に係る計量方法を実施する場合の例であるが、本発明は、これに限らず、前記射出スクリュ３を油圧モータで回転させると共に油圧シリンダで前後進させ、それらを作動させる油圧回路の流量、圧力を調節し、射出スクリュの移動位置を位置センサで直接検出することにより、射出スクリュ３の動作を制御するようにした油圧式射出成形機において実施することもできる。
【００３１】
また、前記実施の形態は、本発明の計量方法を、加熱筒内に可塑化スクリュと射出部材を兼ねた射出スクリュを回転自在にかつ軸方向に前後浸自在に収納した形式のインラインスクリュ式射出成形機において実施する場合の例であるが、本発明は、これに限らず、充填シリンダ内に充填プランジャ（射出部材）が前後進自在に挿入された充填装置と、可塑化加熱筒内に可塑化スクリュを回転自在に挿入された可塑化装置とを備え、可塑化装置の可塑化スクリュを回転させて樹脂材料を可塑化して溶融樹脂を充填シリンダの先端の樹脂溜まり部に供給し、該充填シリンダ内に溶融樹脂を計量し、該計量した溶融樹脂を充填プランジャの前進により金型内へ充填するようにしたプリプラ式射出成形機において実施するようにしてもよい。
【００３２】
【発明の効果】
以上説明したように、本発明によれば以下の優れた効果を奏する。
請求項１に係る射出成形機の計量方法によれば、予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を上まわった場合に、警告メッセージの発生および計量動作の停止の少なくとも一方を行うので、樹脂材料が高粘度樹脂であって、射出部材の設定背圧や加熱筒の設定温度では、樹脂と加熱筒の内壁との摩擦が大きい等の要因により、十分に樹脂の可塑化が進まないか可塑化が行われない異常状態が生じた場合、それをいち早く的確に知ることができて事後の対応処理を適切に行うことができると共に、異常状態で計量動作が無理に継続して機械に故障が発生するのを確実に防止することができる。
【００３３】
請求項２に係る射出成形機の計量方法によれば、予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を下まわった場合に、前記射出部材の背圧の設定値を自動的に変更するので、溶融樹脂が射出ノズルから外部へ漏れ出てしまう恐れがある低粘度樹脂の場合であっても、適時に射出部材の背圧設定値を変更することにより、その後退移動を促進させ、射出部材を計量完了位置に到達させて溶融樹脂の計量を確実に行わせることができる。
【００３４】
請求項３に係る射出成形機の計量方法によれば、射出部材の背圧の設定値を変更する変更回数が予め設定した回数になったとき、計量動作を停止させるので、射出部材の背圧設定値を繰り返し変更しても、計量が確実に行われない異常状態のときは、不要に計量動作が継続するのを確実に防止することができる。
【００３５】
請求項４に係る射出成形機の計量方法によれば、予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を下まわった場合に、前記射出部材を強制的に計量完了位置に後退させた後に、前記射出部材の背圧を監視しながら可塑化スクリュを回転させ、該背圧が前記設定値になったときに計量動作を停止させるので、加熱筒の樹脂溜まり部内の圧力が減圧され、樹脂溜まり部内の溶融樹脂が射出部材のヘッド側への流動が促進され、超低粘度樹脂であっても、射出ノズルからの鼻たれ現象を効果的に防止しながら確実に溶融樹脂の計量を行うことができる。
【図面の簡単な説明】
【図１】本発明に係る射出成形機の計量方法を実施する計量装置を示す系統図である。
【図２】同じく作用を説明するフロー図である。
【図３】同じく作用の他の部分を説明するフロー図である。
【符号の説明】
１計量装置
２加熱筒
３射出スクリュ（射出部材、可塑化スクリュ）
５スクリュ回転用電動サーボモータ（スクリュ回転モータ）
５ａインクレメントエンコーダ（回転速度検出手段）
９スクリュ前後進用電動サーボモータ（射出駆動手段）
９ａアブソリュートエンコーダ（位置検出手段）
１０制御装置
１３圧力センサー（圧力検出手段）
１４コントローラ
１５入力処理手段
１６スクリュ回転制御駆動装置（スクリュ軸制御駆動装置）
１７スクリュ前後進駆動制御駆動装置（射出軸制御駆動装置）
Ａ電動射出成形機（射出成形機）
Ｋ金型[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a measuring method for supplying and measuring a molten resin to a tip portion in a heating cylinder in an injection device of an injection molding machine.
[0002]
[Prior art]
Conventionally, when weighing without touching the mold with a nozzle using an injection molding machine, the resin material introduced into the base end of the heating cylinder is rotated by rotating the injection screw with a minimum set back pressure. When the injection screw retreating by the resin pressure of the molten resin reaches the metering completion position of the retreat end, the rotation of the injection screw is stopped. If necessary, a suck-back operation is performed in which the resin pressure in the resin pool portion is lowered by further retreating from the measurement completion position by a predetermined distance.
However, as described above, in the measuring method in the injection molding machine that performs the measurement without touching the mold with the nozzle, in the case of the ultra-low viscosity resin, even if the minimum set back pressure set in the machine is released, the resin is opened. Since the so-called nasal dripping phenomenon in which the molten resin flows out from the opening of the injection nozzle occurs, there is a problem that the injection screw cannot be retracted to the measurement completion position to complete the measurement. Further, in the case of a high-viscosity resin, if the temperature setting of the heater that heats the heating cylinder is lowered, the friction between the resin material and the heating cylinder is large at the minimum set back pressure, and the resin material is not plasticized. There is a problem that the injection screw retreats to the weighing completion position and the weighing operation cannot be performed normally.
[0003]
Therefore, in order to always ensure normal weighing operation and prevent the occurrence of molding failure due to insufficient plasticization of the resin material, the upper and lower limits for the retreat speed of the injection screw during weighing are set in advance, and The retraction speed of the injection screw is detected, and when the retraction speed deviates from the upper and lower limit values, the rotation of the injection screw is stopped for a set time, and then the injection screw is restarted. In addition to setting the upper and lower limits, the metering time is detected at the time of weighing, and when the weighing time deviates from the upper and lower limits, the rotation of the injection screw is stopped for the set time, and then the injection screw is re-rotated. A weighing method has been proposed in which the weighing is terminated by retracting the weighing position to a target weighing position (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-10-24468
[0005]
[Problems to be solved by the invention]
However, the metering method proposed above is based on the premise that the molding is not interrupted, and the plasticization of the resin material proceeds by repeating the metering operation under predetermined conditions, and the injection screw is completely metered by the resin pressure of the molten resin. It is applicable when the metering is completed by retracting to the position.However, when measuring the ultra-low-viscosity resin or high-viscosity resin without touching the injection nozzle to the mold, the injection nozzle There is a problem that, when an abnormal condition occurs in which the weighing device cannot be moved backward to the weighing completion position, the abnormal condition is detected and the weighing operation cannot be continued or stopped appropriately in response. .
[0006]
The present invention has been made in view of the above circumstances, and when performing measurement without causing the injection nozzle to touch the mold, even if the resin is a super-bottom viscosity resin or a high-viscosity resin, the nose drooping phenomenon of the molten resin is caused. To provide a measuring method of an injection molding machine that can reliably measure a molten resin by preventing the occurrence of an abnormal measuring operation and appropriately stop an abnormal measuring operation in the case of a measurement failure due to a non-plasticization phenomenon of a resin material. With the goal.
[0007]
[Means for Solving the Problems]
The present invention has the following features to solve the above problems.
That is, in the measuring method of the injection molding machine according to claim 1, in a state where the injection nozzle of the heating cylinder is not brought into contact with the mold, the plasticizing screw is rotated to plasticize the resin material, and the resin is contained in the resin reservoir of the heating cylinder. A measuring method for an injection molding machine that supplies a molten resin and measures the molten resin in the resin reservoir based on a retreat position of an injection member that retreats in a heating cylinder while applying a back pressure of a predetermined set value to the molten resin. In advance, a standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set in advance, and the plasticized screw is rotated at a predetermined set rotation speed. When the injection member is retracted and weighed, a warning message is issued when the detected value exceeds a standard retreat speed corresponding to a predetermined set rotational speed of the plasticizing screw. It is characterized by performing at least one of stopping the di- generation and measurement operation.
[0008]
The method of measuring an injection molding machine according to claim 2, wherein the plasticizing screw is rotated to plasticize the resin material in a state where the injection nozzle of the heating cylinder is not brought into contact with the mold, and the molten resin is contained in the resin reservoir of the heating cylinder. In the measuring method of the injection molding machine for measuring the molten resin in the resin reservoir based on the retreat position of the injection member that retreats in the heating cylinder while applying a back pressure of a predetermined set value to the molten resin, In advance, a standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set, and the plasticized screw is rotated at a predetermined set rotation speed. When weighing, the retreat speed of the injection member is detected, and when the detected value falls below a standard retreat speed corresponding to a predetermined set rotation speed of the plasticizing screw, the back pressure of the injection member is reduced. It is characterized in that automatically change the value.
[0009]
According to a third aspect of the present invention, in the weighing method according to the second aspect, the weighing operation is performed when the number of times of changing the set value of the back pressure of the injection member reaches a preset number. It is characterized by stopping.
[0010]
The method for measuring an injection molding machine according to claim 4, wherein the plasticizing screw is rotated to plasticize the resin material in a state where the injection nozzle of the heating cylinder is not brought into contact with the mold, and the molten resin is contained in the resin reservoir of the heating cylinder. In the measuring method of the injection molding machine for measuring the molten resin in the resin reservoir based on the retreat position of the injection member that retreats in the heating cylinder while applying a back pressure of a predetermined set value to the molten resin, In advance, a standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set, and the plasticized screw is rotated at a predetermined set rotation speed. At the time of weighing, the retreat speed of the injection member is detected, and when the detected value falls below a standard retreat speed corresponding to a predetermined set rotation speed of the plasticizing screw, the injection member is forcibly moved. After retracting the metering completion position, wherein by rotating a plasticizing screw while monitoring the back pressure of the injection member is characterized by stopping the measurement operation when the backpressure reaches the set value.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a weighing device that performs a weighing method of an injection molding machine according to the present invention will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a measuring device in an electric injection molding machine (injection molding machine) A. The measuring device 1 includes a heating cylinder 2, an injection screw (plasticizing screw, injection member) 3 that is inserted inside the heating cylinder 2 movably in the axial direction and rotatably in the circumferential direction, and a movable table 4. And an electric servomotor for screw rotation (screw rotation motor) 5 connected to the base end of the injection screw 3 to rotate the injection screw 3, and a nut 6 provided on the movable base 4 with a screw. A screw forward / backward electric servo connected to the screw shaft 7 of a screw mechanism 8 formed by screwing the shaft 7 to move the movable table 4 right and left in FIG. 1 and move the injection screw 3 forward and backward in the axial direction. A motor (injection drive means) 9, an electric servomotor 5 for rotating the screw, and a control device 10 for operating the electric servomotor 9 for moving the screw forward and backward are provided.
[0012]
The metering device 1 is configured such that the fixed mold K1 fixed to the fixed board 11 of the electric injection molding machine A and the movable mold K2 fixed to the movable board 12 are brought into contact with each other and the mold K is clamped. By rotating the screw rotating electric servomotor 5 in a state where the injection nozzle 2a at the tip of the heating cylinder 2 does not contact (no nozzle touch), the hopper 2b on the base end side of the heating cylinder 2 The resin material introduced into the heating cylinder 2 is plasticized, and the molten resin is supplied into the resin reservoir 2 c at the tip of the heating cylinder 2. At this time, by rotating the screw forward / backward moving electric servomotor 9, the movable table 4 is moved via the screw mechanism 8, and the injection screw moves backward with respect to the molten resin supplied into the resin reservoir 2c. 3, a back pressure is applied, the injection screw 3 reaches the metering completion position at the retreating end, and the metering of the molten resin into the resin reservoir 2c is completed.
[0013]
The screw rotating electric servomotor 5 is provided with an increment encoder (rotation speed detecting means) 5a, and the screw forward / backward moving electric servomotor 9 is provided with an absolute encoder (position detecting means) 9a. Further, a pressing force (load) acting on the injection screw 14 is applied to a connection portion between the base end portion of the injection screw 3 and the electric servomotor 5 for screw rotation or a mounting portion of the nut 6 to the movable base 4. A pressure sensor (pressure detecting means) 13 for detecting the measured back pressure of the molten resin is provided. The pressure sensor 13 may directly detect the molten resin in the resin reservoir 2c.
[0014]
Further, the control device 10 is provided with a controller (operation control means) 14 for controlling the entire operation of the electric injection molding machine A including the weighing device 1, and various instruction items and set values are input, and the input setting is performed. An input processing means 15 for performing required arithmetic processing and the like based on the values and displaying various data; and a servo amplifier, and operating based on an operation command from the controller 14 to operate the electric motor for screw rotation. A screw rotation control driving device 16 that supplies a screw rotation speed signal (plasticized screw rotation speed signal) f detected by the increment encoder 5a to the controller 14, and a servo amplifier. When the electric servomotor 9 for screw forward / backward movement is operated by operating based on an operation command from the controller 14, A screw forward / reverse control driving device 17 for supplying a screw position signal (injection member position signal) p detected by the absolute encoder 9a and a pressure signal k detected by the pressure sensor 11 to the controller 14. I have.
[0015]
The screw rotation control drive device 16 feeds back the rotation speed of the screw rotation electric servomotor 5, that is, the rotation speed of the injection screw 3, based on the screw rotation speed signal f detected by the increment encoder 5a. Control. In addition, the screw forward / reverse control drive device 17 determines the rotation amount of the screw forward / reverse electric servomotor 9 based on the screw position signal p detected by the absolute encoder 9a and the pressure signal k detected by the pressure sensor 13. (Rotational position) and rotational force (drive torque), that is, feedback control of the forward / backward traveling position, forward / backward traveling speed, injection pressure, and back pressure of the injection screw 3.
[0016]
The input processing means 15 includes various operation switches for operating the electric injection molding machine A, a speed setting device for setting a forward / backward moving speed of the injection screw 3, an injection pressure acting on the injection screw 3, A pressure setting device for setting back pressure, a position setting device for setting a switching position of a forward and backward moving speed of the injection screw 3, a retreat end position (a measurement completion position) at the time of completion of the measurement of the molten resin, and the like; Rotation speed setting device for setting the rotation speed of the screw, back pressure change frequency setting device for setting the upper limit value of rotation for changing the back pressure of the injection screw 3, characteristic values of the machine and characteristic values of the resin material used for molding , A display for displaying various data, and a warning for notifying an abnormal operation of the weighing device 1 to an operator of the machine by a warning message or the like, and a display for generating a warning. A calculating unit for calculating a standard retreat speed of the injection screw 3 at the time of measurement from the instruction data relating to various items of the machine and the set value of the rotation speed of the injection screw 3 at the time of measurement set in the rotation speed setting device. Have.
[0017]
The controller 14 controls a sequence program for controlling the entire operation of the electric injection molding machine A, various set values (molding conditions of the electric injection molding machine A) set by the setting devices in the input processing means 13, and A memory for storing the standard reverse speed and the like obtained by the calculation in the calculation unit, and a required value based on the set values stored in the memory and the detection values of the increment encoder 5a, the absolute encoder 9a and the pressure sensor 13 To generate various control data for operating the electric injection molding machine 1, and to output the control data to the screw rotation control driving device 16 and the screw forward / reverse driving device 17. And operation control means for outputting required display items to the display of the input processing means 15.
[0018]
Next, the operation of the measuring device 1 in the electric injection molding machine A having the above-described configuration and a method of measuring the molten resin by the measuring device 1 will be described with reference to FIGS. Prior to starting the molding operation by the electric injection molding machine A, the maximum plasticizing capacity Chmax (kg / h) of the electric injection molding machine A to be used, and the maximum rotation speed Rmax (min) of the injection screw 3 at the time of measurement. ^-1 ), The diameter D (cm) of the injection screw 3, the density ρ (kg / l) of the resin material used for molding, and the like are input to the parameter setting device of the input processing means 15, and the injection screw 3 is measured at the time of measurement. Set rotation speed Rsv (min ^-1 ) Is input to the rotational speed setting device of the input processing means 15, and the position setting device, the pressure setting device, and the back pressure change number setting device of the input processing device 15 are respectively used to set the measurement completion position and the measurement of the injection screw 3. The back pressure at the time and the number of times of changing the upper limit of the set value of the back pressure are input and set, and necessary data are also input and set to other setting devices (step S1). The maximum plasticizing capacity Chmax can be obtained by an experiment or by calculation based on design numerical values of the heating cylinder 2, the injection screw 3, and the like.
[0019]
In the input processing means 15, based on each of the key points Chmax, Rmax, D, and ρ input to the key point setting device, the calculation unit sets the rotation of the injection screw 3 at the time of weighing by the following calculation formula. The standard reverse speed Vr corresponding to the speed is calculated, and comparison data to be used in the controller 14 is created based on the set values input to the other setting devices (step S2), and the standard reverse speed Vr is set. And the comparison data are stored in the memory of the controller 14, and a required one of the set values set by each setter is selected and displayed on the display of the input processing means 15.
[0020]
(Equation 1)

[0021]
The display of the input processing means 15 shows a screw rotation speed signal f, a screw position signal p, and a pressure signal detected by the increment encoder 5a, the absolute encoder 9a and the pressure sensor 13 during the weighing operation of the weighing device 1. On the basis of the signal k, the rotational speed of the injection screw 3, the forward / backward moving speed and the forward / backward moving position, and the present value of the back pressure are displayed (step S3).
[0022]
When the setting operation in the input processing means 15 is completed, the operation switch of the input processing means 15 is operated to start the molding operation by the metering device 1 of the electric injection molding machine A. When the molding operation is started, the molding operation is executed in accordance with a sequence program stored in the memory of the controller 14 of the control device 10, and the screw rotation control driving device 16 and the screw forward / reverse control driving device are controlled by a command from the controller 14. The screw rotating electric servomotor 5 and the screw forward / backward moving electric servomotor 9 are respectively rotated via 17 so that the injection screw 3 and the screw shaft 7 are respectively rotated. Due to the rotation of the injection screw 3, the resin material introduced into the heating cylinder 2 from the hopper 2b is plasticized and melted, and is supplied into the resin reservoir 2c of the heating cylinder 2 to start the measuring operation for measuring ( Step S4). At this time, the movable table 4 and the screw rotation which are moved by the screw mechanism 22 by the rotation of the screw shaft 17 are applied to the injection screw 3 which is pressed and retracted by the molten resin supplied into the resin reservoir 2c. A predetermined back pressure set by the pressure setting unit of the input processing means 14 is applied to the molten resin in the resin reservoir 2c by applying a pressing force via the electric servomotor 5 for use.
[0023]
During the metering operation, the retreating position of the injection screw 3 is detected by the absolute encoder 9a, and the screw position signal p is sent to the controller 14 via the screw forward / reverse control driving device 17, and the controller 14 controls the input It is determined whether or not the injection screw 3 has reached the metering completion position set by the processing means 15 (step S5). If the injection screw 3 has reached the metering completion position, the back pressure of a predetermined set value is determined. Assuming that the molten resin has been normally measured in the resin reservoir 2c of the heating cylinder 2, the screw rotation control drive device 16 and the command signals i1 and i2 from the screw forward / reverse control drive device 17 use the electric servo for screw rotation. By stopping the motor 5 and the electric servomotor 9 for moving the screw forward and backward, the rotation and the backward movement of the injection screw 3 are performed. Measurement operation is stopped by stopping (step S6).
[0024]
If the injection screw 3 does not reach the set metering completion position in step S5, the injection screw 3 is retracted calculated by the screw forward / reverse control drive device 17 based on the screw position signal p from the absolute encoder 9a. The current value of the speed is calculated by the input processing means 15 in the controller 14 and compared with the set value of the standard reverse speed Vr stored in the memory of the controller 14 (step S7). Is determined to be significantly higher than the set value of the standard reverse speed Vr (step S8), an alarm of a plasticization error is generated on the display of the input processing means 15, or a warning message is displayed. At the same time as (Step S9), the weighing operation is stopped (Step S6). In this case, the resin material is a high-viscosity resin, and at the set back pressure of the injection screw 3 and the set temperature of the heating cylinder 2, a sufficient amount of resin is generated due to a large friction between the resin and the inner wall of the heating cylinder 2. It can be determined that the injection screw 3 retreats quickly in a state where plasticization does not proceed or plasticization is not performed, and the metering operation is abnormally performed. Therefore, the warning message can include a guide requesting that the operator set an appropriate weighing condition determined based on his or her own experience or increase the set heating temperature of the heating cylinder 2.
[0025]
If it is determined in the comparison result in step S7 that the current value of the retreat speed of the injection screw 3 is significantly lower than the set value of the standard retreat speed Vr (step S10), the controller 14 sets the input value. The back pressure set value set by the pressure setting device of the processing means 15 is replaced with a set back pressure obtained by adding or subtracting a small pressure value to or from a current value of the back pressure detected by the pressure sensor 13. A change is made to lower the value (step S11), and it is determined whether or not the number of times of changing the back pressure set value has reached the number of times of setting change set by the back pressure change number setting unit of the input processing means 14 (step S12). If the number of times of change does not reach the number of times of setting change, the rotation of the injection screw 3 is continued at the changed back pressure set value, and the process returns to the step S5 and starts from the step S5. The operation of up-up S12 is repeated.
[0026]
Then, when the number of times the back pressure set value has been changed reaches the set change number in step S12, the process proceeds to step S6, and the weighing operation is stopped. At this time, a warning message may be generated on the display of the input processing means 15 as in step S9. In this case, even if the resin material is a low-viscosity resin and the back pressure setting value is repeatedly changed, the molten resin leaks from the injection nozzle 2a to the outside, and the injection screw 3 reaches the metering completion position. Otherwise, it is determined that an abnormal state in which the molten resin cannot be measured has occurred. If the number of setting changes has not been reached in step S12, the back screw set value was changed, and a weighing operation was performed using the changed back pressure set value. As a result, the injection screw 3 was set in step S5. When reaching the weighing completion position, it is determined that the weighing has been normally performed, and the process proceeds to step S6 to stop the weighing operation.
Further, when it is determined in the comparison result in the step S7 that the current value of the retreat speed of the injection screw 3 is substantially equal to the set value of the standard retreat speed Vr (step S13), the process returns to the step S5 and returns to the step S5. 3 is confirmed to have reached the metering completion position set by the position setting device of the input processing means 15, and then proceeds to step S6 to measure the molten resin by the back pressure set by the input processing means 14. The weighing operation is stopped assuming that the measurement was performed normally with the set value.
[0027]
If it is determined in the comparison result in step S7 that the current value of the retreat speed of the injection screw 3 is significantly lower than the set value of the standard retreat speed Vr (step S10), as shown in FIG. A different weighing method than the weighing method can be performed.
That is, when it is determined that the current value of the retreat speed is significantly lower than the set value of the standard retreat speed Vr, the controller 14 sets the injection screw 3 to the standard retreat speed, for example, to half the speed. By operating the screw forward / reverse control drive device 17 with the setting, the injection screw 3 is forcibly retracted regardless of the back pressure set value set by the input processing means 14 (step S14). Reaches the metering completion position (step S15), the injection screw 3 starts rotating at the set rotation speed (step S16). During the rotation of the injection screw 3, the measured back pressure is monitored by the controller 14 by the pressure signal k from the pressure sensor 13, and the measured back pressure is measured by the pressure setting unit of the input processing unit 15. The injection screw 3 is rotated until it reaches the back pressure set value set in the step (2). When it is confirmed that the injection screw 3 has reached the set value (step S17), the measuring operation is stopped assuming that the molten resin has been normally measured. (Step S6).
[0028]
According to the measuring method of the injection molding machine according to the embodiment, in the measuring method of performing the measurement without bringing the injection screw 3 into contact with the mold, it is determined in advance based on the plasticizing ability of the electric injection molding machine A. The standard retreat speed Vr corresponding to the set rotation speed of the injection screw 3 is set, and when the injection screw 3 is rotated at a predetermined set rotation speed Rsv and measured, the retreat speed of the injection screw 3 is measured by the absolute encoder 9a. When the detected value exceeds the standard retreat speed Vr corresponding to the predetermined set rotational speed Rsv of the injection screw 3, a warning message is generated on the display of the input processing means 15 and the weighing operation is performed. Since the resin material is a high-viscosity resin, the resin and the heating cylinder 2 are stopped at the set back pressure of the injection screw 3 and the set temperature of the heating cylinder 2. If the plasticization of the resin does not progress sufficiently or the plasticization does not proceed due to factors such as large friction with the inner wall, etc., the abnormal state can be quickly and accurately known, and subsequent measures can be taken The processing can be appropriately performed, and the occurrence of a failure in the machine due to the continued weighing operation in an abnormal state can be reliably prevented.
[0029]
Further, when the injection screw 3 is rotated at a predetermined rotation speed Rsv and measured, the detected value of the retreat speed of the injection screw 3 is set to a standard retreat speed Vr corresponding to the predetermined rotation speed Rsv of the injection screw 3. When the temperature drops below, the set value of the back pressure of the injection screw 3 is automatically changed, and the metering operation is stopped when the number of changes has reached a preset number. Even in the case of a low-viscosity resin that may leak from the injection nozzle 2a to the outside, by changing the back pressure set value of the injection screw 3 in a timely manner, the backward movement is promoted and the injection screw 3 is moved. The molten resin can be reliably measured by reaching the measurement completion position. Further, even if the back pressure set value of the injection screw 3 is repeatedly changed, in an abnormal state where the measurement is not reliably performed, it is possible to reliably prevent the continuation of the measurement operation unnecessarily.
Further, when the injection screw 3 is rotated and measured at a predetermined set rotation speed Rsv, the detected value of the retreat speed of the injection screw 3 is set to a standard retreat speed Vr corresponding to the predetermined set rotation speed Rsv of the injection screw 3. When the injection screw 3 falls, the injection screw 3 is forcibly retracted to the metering completion position, and then the injection screw 3 is rotated while monitoring the back pressure of the injection screw 3 so that the back pressure becomes the set value. When the metering operation is stopped when the temperature rises, the pressure in the resin reservoir 2c of the heating cylinder 2 is reduced, and the molten resin in the resin reservoir 2c is promoted to flow toward the screw head side of the injection screw 3, Even with an ultra-low viscosity resin, it is possible to reliably measure the molten resin while effectively preventing the nose dripping phenomenon from the injection nozzle 2a.
[0030]
In this embodiment, the injection screw 3 inserted into the heating cylinder 2 is rotated by the electric motor 5 for rotating the screw, and the rotation of the electric servomotor 9 for moving the screw forward and backward is connected to the screw shaft 7 by the nut 6. Is converted into linear motion through a screw mechanism 8 into which the screw is screwed, and is moved forward and backward. The rotational speed, back pressure, moving speed, and moving position of the injection screw 3 are respectively adjusted by the input of the electric servomotor 5 for screw rotation. The weighing method according to the present invention is implemented in an electric injection molding machine A that controls the operation of the injection screw 3 by detecting with a clement encoder 5a, a pressure sensor 13, and an absolute encoder 9a of a screw forward / reverse servomotor 19. However, the present invention is not limited to this, and the injection screw 3 is rotated by a hydraulic motor and moved forward and backward by a hydraulic cylinder. The operation is performed in a hydraulic injection molding machine that controls the operation of the injection screw 3 by adjusting the flow rate and pressure of a hydraulic circuit that operates them, and directly detecting the movement position of the injection screw with a position sensor. You can also.
[0031]
The above-described embodiment is directed to an in-line screw injection type in which the measuring method of the present invention is configured such that an injection screw serving as a plasticizing screw and an injection member is rotatably and axially immersed in a heating cylinder. The present invention is not limited to this, but the present invention is not limited to this. The present invention is not limited to this, and a filling device in which a filling plunger (injection member) is inserted in a filling cylinder so as to be able to move forward and backward is provided. A plasticizing device in which a plasticizing screw is rotatably inserted.The plasticizing screw of the plasticizing device is rotated to plasticize the resin material, and the molten resin is supplied to a resin reservoir at the tip of a filling cylinder. The present invention may be applied to a pre-plastic injection molding machine in which a molten resin is measured in a cylinder, and the measured molten resin is filled into a mold by advancing a filling plunger.
[0032]
【The invention's effect】
As described above, the present invention has the following excellent effects.
According to the measuring method of the injection molding machine according to the first aspect, the standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set in advance. When the plasticizing screw is rotated at a predetermined rotation speed and measured, a retreat speed of the injection member is detected, and the detected value is a standard retreat speed corresponding to a predetermined rotation speed of the plasticizing screw. If the temperature exceeds the limit, at least one of the generation of a warning message and the stop of the weighing operation is performed. If the plasticization of the resin does not progress sufficiently or an abnormal state occurs in which plasticization is not performed due to factors such as large friction with the inner wall of the cylinder, etc. It is possible to properly perform, weighed abnormal state operation forcibly continue to fault in the machine can be reliably prevented.
[0033]
According to the measuring method of the injection molding machine according to claim 2, the standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set in advance. When the plasticizing screw is rotated at a predetermined rotation speed and measured, a retreat speed of the injection member is detected, and the detected value is a standard retreat speed corresponding to a predetermined rotation speed of the plasticizing screw. When the temperature is lower than the predetermined value, the set value of the back pressure of the injection member is automatically changed, so that even in the case of a low-viscosity resin in which the molten resin may leak out of the injection nozzle to the outside, it is timely. By changing the back pressure set value of the injection member, the backward movement is promoted, the injection member reaches the measurement completion position, and the molten resin can be reliably measured.
[0034]
According to the measuring method of the injection molding machine according to the third aspect, the metering operation is stopped when the number of times of changing the set value of the back pressure of the injection member reaches a preset number, so that the back pressure of the injection member is reduced. Even if the set value is repeatedly changed, in an abnormal state where the weighing is not reliably performed, it is possible to reliably prevent the weighing operation from continuing unnecessarily.
[0035]
According to the measuring method of the injection molding machine according to claim 4, the standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set in advance. When the plasticizing screw is rotated at a predetermined rotation speed and measured, a retreat speed of the injection member is detected, and the detected value is a standard retreat speed corresponding to a predetermined rotation speed of the plasticizing screw. When the injection member was lowered, the injection member was forcibly retracted to the measurement completion position, and then the plasticizing screw was rotated while monitoring the back pressure of the injection member, and the back pressure became the set value. Since the metering operation is sometimes stopped, the pressure in the resin reservoir of the heating cylinder is reduced, and the molten resin in the resin reservoir is promoted to flow toward the head of the injection member. From the nozzle It is possible to perform a metering of reliably molten resin while effectively preventing the nose sauce phenomenon.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a weighing device for implementing a weighing method for an injection molding machine according to the present invention.
FIG. 2 is a flowchart illustrating the operation of the embodiment.
FIG. 3 is a flowchart illustrating another part of the operation.
[Explanation of symbols]
1 weighing device
2 heating tube
3 Injection screw (injection member, plasticized screw)
5 Screw rotation electric servo motor (screw rotation motor)
5a Increment encoder (rotation speed detection means)
9 Screw-driven forward / backward electric servomotor (injection drive means)
9a Absolute encoder (position detection means)
10 Control device
13. Pressure sensor (pressure detection means)
14 Controller
15 Input processing means
16 Screw rotation control drive (Screw shaft control drive)
17 Screw back and forth drive control drive (injection axis control drive)
A electric injection molding machine (injection molding machine)
K mold

Claims

加熱筒の射出ノズルを金型に接触させない状態で、可塑化スクリュを回転させて樹脂材料を可塑化して前記加熱筒の樹脂溜まり部内に溶融樹脂を供給し、該溶融樹脂に所定設定値の背圧を付加しながら加熱筒内を後退する射出部材の後退位置にもとづいて前記樹脂溜まり部内の溶融樹脂を計量する射出成形機の計量方法において、
予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を上まわった場合に、警告メッセージの発生および計量動作の停止の少なくとも一方を行うことを特徴とする射出成形機の計量方法。In a state where the injection nozzle of the heating cylinder is not brought into contact with the mold, the plasticizing screw is rotated to plasticize the resin material and supply the molten resin into the resin reservoir of the heating cylinder, and the molten resin has a predetermined set value. In a measuring method of an injection molding machine that measures the molten resin in the resin reservoir based on a retreat position of an injection member that retreats in a heating cylinder while applying pressure,
In advance, a standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set, and the plasticized screw is rotated at a predetermined set rotation speed. At the time of weighing, the retreat speed of the injection member is detected, and if the detected value exceeds a standard retreat speed corresponding to a predetermined set rotation speed of the plasticizing screw, a warning message is generated and the weighing operation is performed. A method for measuring an injection molding machine, wherein at least one of stopping is performed.

加熱筒の射出ノズルを金型に接触させない状態で、可塑化スクリュを回転させて樹脂材料を可塑化して前記加熱筒の樹脂溜まり部内に溶融樹脂を供給し、該溶融樹脂に所定設定値の背圧を付加しながら加熱筒内を後退する射出部材の後退位置にもとづいて前記樹脂溜まり部内の溶融樹脂を計量する射出成形機の計量方法において、
予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を下まわった場合に、前記射出部材の背圧の設定値を自動的に変更することを特徴とする射出成形機の計量方法。In a state where the injection nozzle of the heating cylinder is not brought into contact with the mold, the plasticizing screw is rotated to plasticize the resin material and supply the molten resin into the resin reservoir of the heating cylinder, and the molten resin has a predetermined set value. In a measuring method of an injection molding machine that measures the molten resin in the resin reservoir based on a retreat position of an injection member that retreats in a heating cylinder while applying pressure,
In advance, a standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set, and the plasticized screw is rotated at a predetermined set rotation speed. When weighing, the retreat speed of the injection member is detected, and when the detected value falls below a standard retreat speed corresponding to a predetermined set rotation speed of the plasticizing screw, the back pressure of the injection member is set. A weighing method for an injection molding machine, characterized by automatically changing a value.

前記射出部材の背圧の設定値を変更する変更回数が予め設定した回数になったとき、計量動作を停止させることを特徴とする請求項２に記載の射出成形機の計量方法。The method according to claim 2, wherein the measuring operation is stopped when the number of times of changing the set value of the back pressure of the injection member reaches a preset number.

加熱筒の射出ノズルを金型に接触させない状態で、可塑化スクリュを回転させて樹脂材料を可塑化して前記加熱筒の樹脂溜まり部内に溶融樹脂を供給し、該溶融樹脂に所定設定値の背圧を付加しながら加熱筒内を後退する射出部材の後退位置にもとづいて前記樹脂溜まり部内の溶融樹脂を計量する射出成形機の計量方法において、
予め、射出成形機の可塑化能力にもとづいて定めた可塑化スクリュの設定回転速度に対応する射出部材の標準後退速度を設定しておき、前記可塑化スクリュを所定の設定回転速度で回転させて計量する時に、前記射出部材の後退速度を検出して、その検出値が前記可塑化スクリュの所定の設定回転速度に対応する標準後退速度を下まわった場合に、前記射出部材を強制的に計量完了位置に後退させた後に、前記射出部材の背圧を監視しながら可塑化スクリュを回転させ、該背圧が前記設定値になったときに計量動作を停止させることを特徴とする射出成形機の計量方法。In a state where the injection nozzle of the heating cylinder is not brought into contact with the mold, the plasticizing screw is rotated to plasticize the resin material and supply the molten resin into the resin reservoir of the heating cylinder, and the molten resin has a predetermined set value. In a measuring method of an injection molding machine that measures the molten resin in the resin reservoir based on a retreat position of an injection member that retreats in a heating cylinder while applying pressure,
In advance, a standard retreat speed of the injection member corresponding to the set rotation speed of the plasticizing screw determined based on the plasticizing ability of the injection molding machine is set, and the plasticized screw is rotated at a predetermined set rotation speed. When measuring, the retreat speed of the injection member is detected, and when the detected value falls below a standard retreat speed corresponding to a predetermined set rotation speed of the plasticizing screw, the injection member is forcibly measured. After retreating to the completion position, the plasticizing screw is rotated while monitoring the back pressure of the injection member, and the metering operation is stopped when the back pressure reaches the set value. Weighing method.