JP3794610B2 - Control method of injection molding machine - Google Patents

Control method of injection molding machine Download PDF

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Publication number
JP3794610B2
JP3794610B2 JP2000072330A JP2000072330A JP3794610B2 JP 3794610 B2 JP3794610 B2 JP 3794610B2 JP 2000072330 A JP2000072330 A JP 2000072330A JP 2000072330 A JP2000072330 A JP 2000072330A JP 3794610 B2 JP3794610 B2 JP 3794610B2
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heater
heating cylinder
temperature
injection molding
molding machine
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JP2001260193A (en
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晃 伊藤
嘉彦 牧野
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Sumitomo Heavy Industries Ltd
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Sumitomo Heavy 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
    • B29C45/78—Measuring, controlling or regulating of temperature
    • 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
    • B29C2945/76026—Energy, power
    • 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
    • B29C2945/76033—Electric current or voltage
    • 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
    • B29C2945/7611—Velocity
    • B29C2945/7612—Velocity rotational movement
    • 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
    • B29C2945/7618—Injection unit
    • B29C2945/76214—Injection unit drive means
    • 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
    • B29C2945/76367—Metering
    • 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
    • B29C2945/76531—Temperature
    • 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
    • B29C2945/76658—Injection unit
    • B29C2945/76668—Injection unit barrel

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (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の制御方法に関し、特に加熱シリンダの温度制御方法に関する。
【０００２】
【従来の技術】
射出成形機においては、加熱シリンダ内で樹脂を溶融させ、この溶融樹脂を金型のキャビティ内に射出して成形を行う。加熱シリンダの温度、溶融樹脂の射出圧力や保圧等の制御の良し悪しは成型品の品質に大きな影響を与える。このうち、特に加熱シリンダの温度について言えば、内部の樹脂の溶融状態に影響を与える。
【０００３】
射出成形機において樹脂を溶融する手段として次の２種類がある。
【０００４】
Ａ．加熱シリンダの周囲に配設されたヒータに加えられる熱量による溶融。
【０００５】
Ｂ．加熱シリンダ内に配置されたスクリュによって樹脂がせん断されることにより発生する、いわゆるせん断発熱による溶融。
【０００６】
通常の射出成形機では、上記の２つが合わさった状態で樹脂の溶融が行われており、それぞれの比率が変わると樹脂の溶融状態も異なってくる。言い換えれば、加熱シリンダ内の樹脂の溶融の割合は、Ａによる溶融と、Ｂによる溶融の割合が時間によってばらつくことが避けられない。これによって、樹脂の溶融状態がばらつき、計量モータのトルク・計量時間等がばらついてしまう。これらのばらつきは、成型品の品質がばらつく原因となる。
【０００７】
一方、成形に用いる樹脂は、同じ種類であってもロット毎に平均分子量や分子量の分布が微妙に異なるために、同じ温度条件で可塑化しても樹脂の溶融状態に違いが現れる。その結果、計量モータの計量回転時のトルクがロットにより異なってしまっていた。これも成型品の品質がばらつく原因となる。
【０００８】
【発明が解決しようとする課題】
これまで、加熱シリンダの周囲に配設されたヒータの制御は以下のようにして行われている。加熱シリンダには、その温度を検出するために熱電対等による温度センサが設置されている。そして、この温度センサからの検出信号に基づいてヒータへの通電を制御するためのコントローラが備えられている。コントローラは、ソリッドステートリレー（以下、ＳＳＲと呼ぶ）のような通電制御手段を介してヒータへの通電を制御する。すなわち、加熱シリンダの温度を安定に保つために、温度センサを用いて加熱シリンダの温度を計測し、その結果から、ヒータに流す電流をコントロールしているＳＳＲをコントローラで制御し、温度を制御するようにしている。
【０００９】
しかし、温度条件が同じでロットの異なる樹脂を用いた場合、前に述べたように、加熱シリンダ内の樹脂の溶融状態の割合（せん断発熱による溶融とヒータ発熱による溶融との割合）が異なる。その結果、計量回転時の計量モータのトルクが樹脂のロットにより異なってしまう。これに対して、従来は熟練技能者が成型品の品質を確認しながら、加熱シリンダの温度設定を手動で変えて対処しており、熟練を必要としていた。
【００１０】
そこで、本発明の課題は、樹脂のせん断発熱による溶融とヒータ発熱による溶融の割合を制御できるようにして、樹脂のロットによらずに計量モータのトルクを安定させることのできる射出成形機の制御方法を提供することにある。
【００１１】
【課題を解決するための手段】
本発明による射出成形機の制御方法は、加熱シリンダの周囲にヒータが配設されると共に、温度センサが設置され、前記温度センサからの検出信号を受けて前記ヒータへの通電を通電制御手段を介して制御するコントローラを備えた射出成形機において、あらかじめ良品が得られる時の計量モータのトルクモデルを求めておき、前記コントローラは、実成形に際しては、前記トルクモデルに近付くように前記通電制御手段を制御し、しかも該通電制御手段は、実際の計量モータのトルクが前記トルクモデルより大きい場合、前記加熱シリンダの温度を上げるように制御し、実際の計量モータのトルクが前記トルクモデルより小さい場合、前記加熱シリンダの温度を下げるように制御し、前記コントローラは、前記トルクモデルにおけるヒータによる発熱量と樹脂のせん断発熱量との比率モデルを保存しており、前記加熱シリンダの温度制御に際しては前記比率モデルに近付くように制御することを特徴とする。
【００１３】
本制御方法においてはまた、前記加熱シリンダ内に樹脂が充填されしかもスクリュを回転させない状態にて、前記ヒータにより発生される熱量と前記加熱シリンダの温度との対応関係をあらかじめ計測しておき、前記コントローラは、実成形において前記通電制御手段により前記ヒータに与えられた電流及び時間とに基づいて前記ヒータにより発生される熱量を算出し、更に前記対応関係と算出された熱量とに基づいて前記ヒータの発熱による温度上昇分を求め、実成形において検出された加熱シリンダ温度と前記ヒータの発熱による温度上昇分との差又は割合を前記せん断発熱による温度上昇分として算出し、更にロギングデータとして出力するようにしても良い。
【００１４】
前記通電制御手段はソリッドステートリレーで実現することができる。
【００１５】
前記算出された差又は割合は成型品の品質情報として記録あるいは表示するようにされても良い。
【００１６】
【発明の実施の形態】
図１を参照して、本発明の実施の形態について説明する。図１において、加熱シリンダ１０の周囲にはヒータ１１が配設されている。図１ではヒータ１１は象徴的に１個のみ示しているが、実際には加熱シリンダ１０の軸方向に間隔をおいて複数箇所に設置される。ヒータ１１には、その温度を加熱シリンダ１０の温度として検出するために熱電対等による温度センサ１２が設置されている。そして、温度センサ１２からの検出信号及び後述する情報に基づいてヒータ１１への通電を制御するためのコントローラ１３が備えられている。コントローラ１３は、ＳＳＲによる通電制御部１４を介してヒータ１１への通電を制御する。
【００１７】
本発明による制御方法は以下のようにして実行される。
【００１８】
（１）条件出し作業において良品が得られた時の計量モータのトルクモデルをあらかじめ基準モデルとして求めておく。この基準モデルは、１ショット当たりのスクリュ位置と計量モータのトルクとの対応関係を示しており、コントローラ１３内のメモリに保存される。また、基準のトルクモデルにおけるヒータによる発熱量と樹脂のせん断発熱量との比率モデルを求めておく。この比率モデルは、１ショット当たりのスクリュ位置に対する前記ヒータによる発熱量と樹脂のせん断発熱量の比率を示しており、コントローラ１３内のメモリに保存される。なお、スクリュ位置は既設のスクリュ位置センサで知ることができ、計量モータのトルクは供給される電流値から算出することができる。
【００１９】
図２は求められた基準モデルの一例を示す。
【００２０】
（２）コントローラ１３は、実成形に際しては、上記の基準モデルに近付くように通電制御部１４を制御する。図３は、実成形における１ショット当たりのスクリュ位置と計量モータのトルクとの対応関係の一例を示している。前に述べた理由で、実際のスクリュ位置と計量モータのトルクとの対応関係と、図２に示された基準モデルとの間には差が生じる。コントローラ１３は、１ショットの間にスクリュ位置センサから得られるスクリュ位置と計量モータの電流値をサンプリングして電流値からトルクを算出し、スクリュ位置と計量モータのトルクとの対応関係を基準モデルと比較する。そして、実際の対応関係と基準モデルとの間の差を無くすように通電部１４を制御する。
【００２１】
例えば、実際の計量モータのトルクが基準モデルにおけるトルクより高めであった場合には、樹脂の溶融を促進するためにヒータ１１による発熱量を増やすように制御する。これは、基準トルクより実際のトルクが高いということは、樹脂の溶融が促進されていないということであり、この場合、ヒータ１１の発熱量を増して樹脂の溶融を促進させる。一方、基準トルクより実際のトルクが低い場合には、樹脂の溶融が促進されすぎてサラサラの状態になっている可能性が大であるので、ヒータ１１の発熱量を下げるか、ヒータ１１への電力供給を遮断する。但し、ヒータ１１の発熱量をむやみに変動させることは、せん断発熱による溶融とヒータ発熱による溶融のバランスをくずすことになるので、これらの割合を考慮して通電制御部１４に対する制御を行う。
【００２２】
すなわち、上記の制御に際しては、通電制御部１４に対する制御ゲインを、前記比率モデルから加熱シリンダ１０内の樹脂のせん断発熱量とヒータ１１の発熱量の割合を求めてその割合に近付くように制御する。
【００２３】
せん断発熱による温度上昇分の算出は以下のようにして行われる。
【００２４】
（Ａ）あらかじめ、せん断発熱させない場合、すなわち加熱シリンダ１０内に樹脂を充填ししかもスクリュを回転させない場合における、ヒータ１１により発生される熱量（ヒータに流れる電流値と通電時間とにより算出される）とヒータ１１における温度上昇、すなわち加熱シリンダ１０の温度上昇（温度センサ１２の検出値）との対応関係を求めておく。この対応関係もコントローラ１３内のメモリに保存される。図４は、上記の対応関係の一例を示す。
【００２５】
（Ｂ）実成形に入ると、コントローラ１３は温度センサ１２による検出温度をサンプリングして記憶すると共に、ヒータ１１に流される電流とその時間とによりヒータ１１で発生される熱量を上記サンプリング周期で算出して記憶する。
【００２６】
（Ｃ）コントローラ１３は更に、上記（Ａ）、（Ｂ）で得られた情報、すなわち前記対応関係と算出された熱量とに基づいて、実成形において検出された加熱シリンダ温度とヒータ１１の発熱による温度上昇分との差又は割合をせん断発熱による温度上昇分として算出して出力する。これはプリンタにより記録したり、ディスプレイにて表示することができる。
【００２７】
図５には、実際の加熱シリンダ１０の温度上昇（せん断発熱よる上昇分を含む）とヒータ１１の発熱量との関係の一例を示す。ここで、図５に示されたあるヒータ発熱量での加熱シリンダ温度と、図４に示された上記あるヒータ発熱量での加熱シリンダ温度との差又は割合が、せん断発熱によるものであることは明らかである。
【００２８】
このようにして、上記の対応関係からせん断発熱分を知ることができ、その推移を知ることもできる。これは、樹脂の溶融状態を左右しているせん断発熱とヒータ１１の発熱との割合の変化の推移が分かることを意味する。せん断発熱分の推移は、コントローラ１３から成型品の品質情報の１つとして出力される。
【００２９】
（Ｄ）上記のようにして、せん断発熱量とヒータによる発熱量とを求め、それらを前記比率モデルに近付くように制御ゲインによってヒータ１１への通電が制御されることにより、樹脂のせん断発熱による溶融とヒータ１１の発熱による溶融の割合が制御される。その結果、樹脂のロットが変わっても樹脂の溶融状態が安定し、計量モータのトルクが基準モデルに近付いて安定する。
【００３０】
本形態によれば、加熱シリンダ１０の温度とヒータ１１に流す電流を調整している通電制御部１４の出力とにより、加熱シリンダ１０の温度上昇におけるせん断発熱の割合がわかる。よって、コントローラ１３の出力により、せん断発熱の推移がわかり、樹脂の溶融状態の推移を知ることができると共に、成型品の品質情報として出力することができる。勿論、上記（１）、（３）、（Ａ）〜（Ｃ）におけるヒータ１１の温度設定条件は同じである。
【００３１】
なお、コントローラ１３は、射出成形機本体を制御するために備えられている制御装置で実現することもできるし、この制御装置とは別に専用に備えられても良い。また、本発明は、計量回転モータが電動の油圧式、電動式のいずれのタイプの射出成形機にも適用できることは言うまでも無い。
【００３２】
【発明の効果】
本発明によれば、樹脂のロットが変わっても加熱シリンダにおけるヒータによる樹脂溶融とせん断発熱による樹脂溶融との割合を安定させることができて樹脂の溶融状態を均一にすることができるので、計量モータのトルクが安定し、もって成型品の品質のばらつきを無くすことができる。また、せん断発熱の推移もロギングデータとして知ることができる。
【図面の簡単な説明】
【図１】本発明による制御方法を実施するための構成を示したブロック図である。
【図２】本発明において求められる計量モータのトルクとスクリュ位置との関係の基準モデルの一例を示した図である。
【図３】実成形における計量モータのトルクとスクリュ位置との対応関係の実際の例を示した図である。
【図４】スクリュを回転させずヒータのみの発熱で樹脂の溶融を行った場合のヒータ発熱量と加熱シリンダ温度との関係を示した図である。
【図５】スクリュを回転させてせん断発熱とヒータの発熱で樹脂の溶融を行った場合のヒータ発熱量と加熱シリンダ温度との関係を示した図である。
【符号の説明】
１０ 加熱シリンダ
１１ ヒータ
１２ 温度センサ
１３ コントローラ
１４ 通電制御部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control method for an injection molding machine, and more particularly to a temperature control method for a heating cylinder.
[0002]
[Prior art]
In an injection molding machine, resin is melted in a heating cylinder, and this molten resin is injected into a cavity of a mold to perform molding. The control of the temperature of the heating cylinder, the injection pressure and the holding pressure of the molten resin has a great influence on the quality of the molded product. Among these, especially regarding the temperature of the heating cylinder, it affects the molten state of the resin inside.
[0003]
There are the following two types of means for melting the resin in the injection molding machine.
[0004]
A. Melting due to the amount of heat applied to the heater around the heating cylinder.
[0005]
B. Melting due to so-called shearing heat generated when the resin is sheared by a screw arranged in a heating cylinder.
[0006]
In a normal injection molding machine, the resin is melted in a state where the above two are combined, and when the respective ratios change, the molten state of the resin also differs. In other words, the melting rate of the resin in the heating cylinder is unavoidable that the melting rate due to A and the melting rate due to B vary with time. As a result, the molten state of the resin varies, and the torque and measuring time of the measuring motor vary. These variations cause variations in the quality of the molded product.
[0007]
On the other hand, even if the resin used for molding is the same type, the average molecular weight and molecular weight distribution are slightly different for each lot, so that even when plasticized under the same temperature condition, a difference in the molten state of the resin appears. As a result, the torque at the time of metering rotation of the weighing motor differs depending on the lot. This also causes the quality of the molded product to vary.
[0008]
[Problems to be solved by the invention]
Until now, the control of the heater arranged around the heating cylinder has been performed as follows. The heating cylinder is provided with a temperature sensor such as a thermocouple in order to detect its temperature. And the controller for controlling electricity supply to a heater based on the detection signal from this temperature sensor is provided. The controller controls energization of the heater via energization control means such as a solid state relay (hereinafter referred to as SSR). That is, in order to keep the temperature of the heating cylinder stable, the temperature of the heating cylinder is measured using a temperature sensor, and from the result, the SSR that controls the current flowing to the heater is controlled by the controller, and the temperature is controlled. I am doing so.
[0009]
However, when resins having the same temperature conditions and different lots are used, as described above, the ratio of the molten state of the resin in the heating cylinder (the ratio of melting due to shear heat generation and melting due to heater heat generation) is different. As a result, the torque of the metering motor during metering rotation varies depending on the resin lot. Conventionally, skilled technicians have dealt with manually changing the temperature setting of the heating cylinder while checking the quality of the molded product, which requires skill.
[0010]
Therefore, an object of the present invention is to control an injection molding machine that can stabilize the torque of the metering motor regardless of the lot of the resin, by controlling the melting ratio of the resin due to the shear heat generation and the heater heat generation. It is to provide a method.
[0011]
[Means for Solving the Problems]
In the injection molding machine control method according to the present invention, a heater is disposed around the heating cylinder, a temperature sensor is installed, and an energization control means is provided for energizing the heater in response to a detection signal from the temperature sensor. In an injection molding machine equipped with a controller to be controlled via a controller, a torque model of a metering motor when a good product is obtained is obtained in advance, and the controller controls the energization control means so as to approach the torque model during actual molding. And the energization control means controls to increase the temperature of the heating cylinder when the torque of the actual metering motor is larger than the torque model, and when the torque of the actual metering motor is smaller than the torque model. the controlled to lower the temperature of the heating cylinder, wherein the controller, the heater in the torque model And it saves the ratio model and shear heating value of the heating value and the resin by, when the temperature control of the heating cylinder and controls so as to approach the said ratio model.
[0013]
In this control method, the correspondence relationship between the amount of heat generated by the heater and the temperature of the heating cylinder is measured in advance in a state where the resin is filled in the heating cylinder and the screw is not rotated. the controller, based on said energization control the current and time given to the heater by the means in the real molding calculates the amount of heat generated by said heater, said on the basis of the further heat the calculated and correspondence heater calculated temperature rise due to heat generation of the difference or ratio between the temperature rise and the detected heating cylinder temperature due to heat generation of the heater in a real molded calculated as a temperature rise by the shearing heat generation, and output as still logging data You may do it.
[0014]
The energization control means can be realized by a solid state relay.
[0015]
The calculated difference or ratio may be recorded or displayed as quality information of a molded product.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. In FIG. 1, a heater 11 is disposed around the heating cylinder 10. Although only one heater 11 is shown symbolically in FIG. 1, it is actually installed at a plurality of locations at intervals in the axial direction of the heating cylinder 10. The heater 11 is provided with a temperature sensor 12 such as a thermocouple in order to detect the temperature as the temperature of the heating cylinder 10. And the controller 13 for controlling electricity supply to the heater 11 based on the detection signal from the temperature sensor 12 and the information mentioned later is provided. The controller 13 controls energization to the heater 11 via the energization control unit 14 by SSR.
[0017]
The control method according to the present invention is executed as follows.
[0018]
(1) A torque model of the weighing motor when a good product is obtained in the condition setting operation is obtained in advance as a reference model. This reference model shows the correspondence between the screw position per shot and the torque of the metering motor, and is stored in the memory in the controller 13. In addition, a ratio model between the heat generation amount by the heater and the shear heat generation amount of the resin in a standard torque model is obtained. This ratio model indicates the ratio of the amount of heat generated by the heater and the amount of shear heat generated by the resin with respect to the screw position per shot, and is stored in a memory in the controller 13. The screw position can be known with an existing screw position sensor, and the torque of the metering motor can be calculated from the supplied current value.
[0019]
FIG. 2 shows an example of the obtained reference model.
[0020]
(2) During actual molding, the controller 13 controls the energization control unit 14 so as to approach the reference model. FIG. 3 shows an example of the correspondence between the screw position per shot in actual molding and the torque of the metering motor. For the reasons described above, there is a difference between the correspondence between the actual screw position and the torque of the metering motor and the reference model shown in FIG. The controller 13 samples the screw position obtained from the screw position sensor and the current value of the metering motor during one shot, calculates the torque from the current value, and determines the correspondence between the screw position and the torque of the metering motor as a reference model. Compare. And the electricity supply part 14 is controlled so that the difference between an actual correspondence and a reference | standard model may be eliminated.
[0021]
For example, when the actual torque of the metering motor is higher than the torque in the reference model, control is performed to increase the amount of heat generated by the heater 11 in order to promote the melting of the resin. The fact that the actual torque is higher than the reference torque means that the melting of the resin is not promoted. In this case, the heat generation amount of the heater 11 is increased to promote the melting of the resin. On the other hand, when the actual torque is lower than the reference torque, there is a high possibility that the melting of the resin is promoted too much to be in a smooth state. Shut off the power supply. However, if the amount of heat generated by the heater 11 is changed unnecessarily, the balance between melting due to shear heat generation and melting due to heater heat generation is lost, and thus the energization control unit 14 is controlled in consideration of these ratios.
[0022]
That is, in the above control, the control gain for the energization control unit 14 is controlled so that the ratio between the heat generation amount of the resin in the heating cylinder 10 and the heat generation amount of the heater 11 is obtained from the ratio model and approaches that ratio. .
[0023]
Calculation of the temperature rise due to shearing heat generation is performed as follows.
[0024]
(A) The amount of heat generated by the heater 11 (calculated by the current value flowing through the heater and the energization time) when the heat is not generated in advance, that is, when the heating cylinder 10 is filled with resin and the screw is not rotated. And the temperature rise in the heater 11, that is, the temperature rise of the heating cylinder 10 (detected value of the temperature sensor 12) is obtained. This correspondence is also stored in the memory in the controller 13. FIG. 4 shows an example of the above correspondence.
[0025]
(B) When actual molding is started, the controller 13 samples and stores the temperature detected by the temperature sensor 12, and calculates the amount of heat generated by the heater 11 in accordance with the sampling period based on the current passed through the heater 11 and its time. And remember.
[0026]
(C) The controller 13 further determines the heating cylinder temperature detected in the actual molding and the heat generation of the heater 11 based on the information obtained in the above (A) and (B), that is, the correspondence relationship and the calculated heat quantity. The difference or rate from the temperature rise due to is calculated and output as the temperature rise due to shear heating. This can be recorded by a printer or displayed on a display.
[0027]
FIG. 5 shows an example of the relationship between the actual temperature rise of the heating cylinder 10 (including the rise due to shear heat generation) and the amount of heat generated by the heater 11. Here, the difference or ratio between the heating cylinder temperature at a certain heater heating value shown in FIG. 5 and the heating cylinder temperature at the certain heater heating value shown in FIG. 4 is due to shear heating. Is clear.
[0028]
In this way, it is possible to know the amount of shear heat generation from the above correspondence, and it is also possible to know its transition. This means that the transition of the change in the ratio between the shear heat generation that influences the molten state of the resin and the heat generation of the heater 11 can be known. The transition of the amount of heat generated by shearing is output from the controller 13 as one of quality information of the molded product.
[0029]
(D) As described above, the amount of heat generated by the shear and the amount of heat generated by the heater are obtained, and the energization to the heater 11 is controlled by the control gain so that they approach the ratio model. The rate of melting and melting due to the heat generated by the heater 11 is controlled. As a result, even if the resin lot changes, the molten state of the resin becomes stable, and the torque of the metering motor approaches the reference model and stabilizes.
[0030]
According to this embodiment, the ratio of the shear heat generation in the temperature rise of the heating cylinder 10 can be understood from the temperature of the heating cylinder 10 and the output of the energization control unit 14 that adjusts the current flowing through the heater 11. Therefore, the transition of the shear heat generation can be known from the output of the controller 13, the transition of the molten state of the resin can be known, and the quality information of the molded product can be output. Of course, the temperature setting conditions of the heater 11 in the above (1), (3), and (A) to (C) are the same.
[0031]
The controller 13 can be realized by a control device provided for controlling the injection molding machine main body, or may be provided exclusively for this control device. Further, it goes without saying that the present invention can be applied to any type of injection molding machine in which the metering rotation motor is an electric hydraulic type or an electric type.
[0032]
【The invention's effect】
According to the present invention, even if the resin lot changes, the ratio of the resin melting by the heater in the heating cylinder and the resin melting by the shear heat generation can be stabilized and the molten state of the resin can be made uniform. The torque of the motor is stabilized, so that variations in the quality of the molded product can be eliminated. In addition, the transition of shear heat generation can be known as logging data.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration for carrying out a control method according to the present invention.
FIG. 2 is a diagram showing an example of a reference model of the relationship between the torque of the weighing motor and the screw position required in the present invention.
FIG. 3 is a diagram showing an actual example of the correspondence relationship between the torque of the metering motor and the screw position in actual molding.
FIG. 4 is a diagram showing the relationship between the amount of heat generated by the heater and the heating cylinder temperature when the resin is melted by the heat generated only by the heater without rotating the screw.
FIG. 5 is a diagram showing the relationship between the amount of heat generated by a heater and the temperature of a heating cylinder when a resin is melted by rotating the screw and generating heat by shearing and heating from the heater.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Heating cylinder 11 Heater 12 Temperature sensor 13 Controller 14 Current supply control part

Claims (4)

加熱シリンダの周囲にヒータが配設されると共に、温度センサが設置され、前記温度センサからの検出信号を受けて前記ヒータへの通電を通電制御手段を介して制御するコントローラを備えた射出成形機において、
あらかじめ良品が得られる時の計量モータのトルクモデルを求めておき、
前記コントローラは、実成形に際しては、前記トルクモデルに近付くように前記通電制御手段を制御し、しかも該通電制御手段は、実際の計量モータのトルクが前記トルクモデルより大きい場合、前記加熱シリンダの温度を上げるように制御し、実際の計量モータのトルクが前記トルクモデルより小さい場合、前記加熱シリンダの温度を下げるように制御し、
前記コントローラは、前記トルクモデルにおけるヒータによる発熱量と樹脂のせん断発熱量との比率モデルを保存しており、前記加熱シリンダの温度制御に際しては前記比率モデルに近付くように制御することを特徴とする射出成形機の制御方法。An injection molding machine comprising a controller in which a heater is disposed around the heating cylinder, a temperature sensor is installed, and energization of the heater is controlled via energization control means in response to a detection signal from the temperature sensor In
Obtain the torque model of the weighing motor when a good product is obtained in advance.
In actual molding, the controller controls the energization control means so as to approach the torque model, and the energization control means controls the temperature of the heating cylinder when the actual metering motor torque is larger than the torque model. If the actual metering motor torque is smaller than the torque model, the temperature of the heating cylinder is controlled to be lowered ,
The controller stores a ratio model of a heat generation amount by a heater and a shear heat generation amount of a resin in the torque model, and controls the temperature of the heating cylinder so as to approach the ratio model. Control method of injection molding machine. 請求項１記載の射出成形機の制御方法において、
前記加熱シリンダ内に樹脂が充填されしかもスクリュを回転させない状態にて、前記ヒータにより発生される熱量と前記加熱シリンダの温度との対応関係をあらかじめ計測しておき、
前記コントローラは、実成形において前記通電制御手段により前記ヒータに与えられた電流及び時間とに基づいて前記ヒータにより発生される熱量を算出し、更に前記対応関係と算出された熱量とに基づいて前記ヒータの発熱による温度上昇分を求め、実成形において検出された加熱シリンダ温度と前記ヒータの発熱による温度上昇分との差又は割合を前記せん断発熱による温度上昇分として算出し、更にロギングデータとして出力することを特徴とする射出成形機の制御方法。In the control method of the injection molding machine according to claim 1,
In a state where the heating cylinder is filled with resin and the screw is not rotated, the correspondence between the amount of heat generated by the heater and the temperature of the heating cylinder is measured in advance,
The controller, based on said energization control the current and time given to the heater by the means in the real molding calculates the amount of heat generated by said heater, said based on the further the calculated and correspondence heat calculated temperature rise due to heat generation of the heater, the difference or ratio between the temperature rise and the detected heating cylinder temperature due to heat generation of the heater in a real molded calculated as a temperature rise by the shearing heat generation, and the output as a logging data A control method for an injection molding machine. 請求項１あるいは２記載の射出成形機の制御方法において、前記通電制御手段はソリッドステートリレーであることを特徴とする射出成形機の制御方法。 3. The method of controlling an injection molding machine according to claim 1, wherein the energization control means is a solid state relay . 請求項２記載の射出成形機の制御方法において、前記算出された差又は割合を成型品の品質情報として記録あるいは表示することを特徴とする射出成形機の制御方法。A control method for an injection molding machine according to claim 2 Symbol placement, control method of an injection molding machine, characterized in that the record or display the difference or ratio the calculated as the quality information of the molded article.
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JP4638533B2 (en) * 2008-09-08 2011-02-23 住友重機械工業株式会社 Injection molding machine and temperature monitoring method thereof
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