JP3782980B2 - Electric injection molding machine injection control method - Google Patents

Electric injection molding machine injection control method Download PDF

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Publication number
JP3782980B2
JP3782980B2 JP2002106678A JP2002106678A JP3782980B2 JP 3782980 B2 JP3782980 B2 JP 3782980B2 JP 2002106678 A JP2002106678 A JP 2002106678A JP 2002106678 A JP2002106678 A JP 2002106678A JP 3782980 B2 JP3782980 B2 JP 3782980B2
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injection
pressure
speed
screw
molding machine
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JP2003300236A (en
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誠 行広
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株式会社日本製鋼所
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17Component parts, details or accessories; Auxiliary operations
    • B29C45/76Measuring, controlling or regulating
    • B29C45/77Measuring, controlling or regulating of velocity or pressure of moulding material

Description

【0001】
【発明の属する技術分野】
本発明は、シリンダ内の溶融材料を、電動モータを駆動させることによりスクリュを前進させて、金型のキャビティ内に射出して成形品を成形する電動射出成形機の射出制御方法に関する。
【0002】
【従来の技術】
電動射出成形機における射出成形は、概ね、金型を閉じる型閉じ工程と、金型を締め付ける型締め工程と、金型のスプルにノズルを押しつけるノズルタッチ工程と、電動モータでスクリュに接続されているボールネジを回転させることでシリンダ内のスクリュを前進させて、スクリュ前方に溜まった溶融材料を金型キャビティ内に射出する射出工程と、その後、気泡、ヒケの発生を抑制するために保圧圧力をしばらくかける保圧工程と、金型キャビティ内に充填された溶融材料が冷却されて固まるまでの間の時間に次のサイクルのために、スクリュを回転させて、樹脂を溶融しながらシリンダの前方にため込む可塑化工程と、固化された成形品を金型から取り出すために、金型を開き、成形品を金型に設けられた突出しピンによって押し出す型開き・成形品突出し工程とからなる。
【0003】
図5に、従来の、射出工程から保圧工程に至るまでの、射出保圧時間tに対する、射出速度Vおよび射出圧力Pの関係を表すグラフを示す。
【0004】
一般に、射出成形における射出制御は、スクリュを設定された速度で前進させて、射出時間とともに溶融材料の金型キャビティ内への充填量が増加するに伴い、射出圧力Pが上昇し、金型キャビティ内に充填された溶融材料がフルパックになる手前の保圧切換位置で速度制御から圧力制御に切り換え、次いで保圧圧力をしばらくかける保圧工程に移行するという方法がとられる。また、オペレータは速度制御されている射出工程中に、射出圧力Pが射出制限圧力Paを越えないような、射出速度と射出制限圧力を設定するのが一般的である。
【0005】
しかしながら、射出中に異常な状態、例えば、金型キャビティ内がフルパックされても保圧切換位置に達しないで高速を維持するような間違った成形条件で射出した場合や、充填中にノズルや金型ゲートなどの絞られた流路部分で溶融材料の詰まりを生じてしまった場合には、図6に示すように、急激に圧力が上昇し射出圧力Pが射出制限圧力Paに達することがあり得る。
【0006】
このような場合、従来の制御方法においては、射出圧力Pが射出制限圧力Paに達した場合には、射出速度Vを制動させて射出圧力Pの上昇を制限し、射出制限圧力Paを維持する圧力制御が一般的に適用されている。
【0007】
【発明が解決しようとする課題】
しかしながら、電動射出成形機で、射出中の圧力Pが射出制限圧力Paに近づいたときに、前述の異常な状態が発生し、射出圧力Pが急激に上昇して射出制限圧力Paに達するような事態が発生した場合、上述した制御にて電動モータに急制動をかけて射出速度Vを急減速させて圧力の上昇を止めようとしても、電動モータの回転子、スクリュをその軸線を中心に回転可能に軸支する軸受け部、軸受け部に組付けられたボールネジ機構部、電動モータの動力をボールネジ機構部に伝えるタイミングベルトやプーリ、スクリュといった駆動系の慣性があるため、減速中にわずかにスクリュが前進すること、すなわち、慣性流れを避けることができない。スクリュの慣性流れ量は、一般に射出速度×減速時間/2であり、この時、例えば、ノズル詰まりを起こすと、スクリュ先端からノズル先端までの溶融材料が圧縮されることにより圧力上昇を起こし、射出圧力Pが射出制限圧力Paを越え、さらに射出装置や金型を破損させない限界圧力PLをも越えて異常圧力Pbにまで達することとなる。また、ある速度から速度0に減速時の昇圧分は、一般に最大射出速度時の昇圧分×(射出速度/最大射出速度)2で表される。すなわち、射出速度が低い時は、慣性流れによる昇圧分は小さいので問題にはならないが、速度が最大射出速度に近づいてくると昇圧分が極めて大きな圧力になり、この結果、射出装置、あるいは金型を破損してしまうおそれがあった。なお、射出制限圧力Paとは、繰り返し作用する圧力に対して金型を損傷させない制限圧力、あるいは成形品の寸法が許容寸法を外れるなどの成形品質上の制限圧力であり、限界圧力PLとは、異常時に射出装置や金型を破損させない単発の限界圧力である。
【0008】
そこで、本発明は、誤った成形条件、あるいは溶融材料の詰まりに起因する異常な圧力上昇により射出圧力が限界圧力を越えてしまうことのない安全な電動射出成形機の射出制御方法を提供することを目的とする。
【0009】
【課題を解決するための手段】
上記目的を達成するため、本発明の電動射出成形機の射出制御方法は、シリンダ内のスクリュの前進速度、および射出圧力に基づき、ボールネジを介してスクリュを移動させる射出サーボモータの回転速度を制御して、金型のキャビティ内への溶融材料の射出を制御する電動射出成形機の射出制御方法において、コントローラから射出サーボモータに制動信号を送信してからスクリュの速度が0となるまでの減速時に上昇する圧力である慣性流れ時昇圧ΔPを予め求めておき、その値と限界圧力PLとをコントローラの記憶部に記憶させておき、コントローラの比較部にて、射出中にロードセルにより常時測定されているシリンダ内の溶融材料の射出圧力と慣性流れ時昇圧ΔPとの和と、限界圧力PLとを比較し、P+ΔP≧PLの場合、すなわち、P≧PL−ΔPに達したとき(この時の射出圧をPmとする)、射出サーボモータに急制動信号を送信してスクリュの前進速度を0まで減速する工程を含むことを特徴とする。
【0010】
上記の通り、本発明の電動射出成形機の射出制御方法は、射出中に、射出できなくなるような異常な状態が発生した時に、その時の射出速度から急制動した時の慣性流れによる射出圧力の上昇、すなわち、慣性流れ時昇圧ΔPを予め求めておき、この慣性流れ時昇圧ΔPと、ロードセルにより常時測定されているシリンダ内の溶融材料の射出圧力Pとの和を限界圧力PLと比較しながら射出を行う。つまり、本発明の電動射出成形機の射出制御方法は、射出中に異常な状態が生じた場合でも、射出サーボモータにブレーキをかけて制動する際に生じるスクリュの慣性流れ時の昇圧分である慣性流れ時昇圧ΔPを見込んで射出サーボモータの速度制御を行うため、万一射出できなくなるような異常な状態が発生したときにおいても射出成形機、あるいは金型に限界圧力PLを越える圧力がかかることがない。
【0011】
また、本発明の電動射出成形機の射出制御方法は、コントローラにて、最大射出速度をVmax、最大射出速度時の昇圧分をΔPmaxとしたとき、任意の射出速度Vdでの昇圧分ΔPを、ΔP=ΔPmax×(Vd/Vmax)2として求める工程を含むものであってもよい。
【0013】
【発明の実施の形態】
次に、本発明の実施の形態について図面を参照して説明する。
【0014】
図1に、本発明の一実施形態である電動射出成形機の射出装置の概略構成図を示す。
【0015】
電動射出成形機の射出装置は、シリンダ1と、シリンダ1内に回転および前後進可能に挿入され、先端にスクリュヘッド2を備えたスクリュ3と、スクリュヘッド2と反対側のスクリュ3の一端に、射出時のスクリュ3の反力による歪みを射出圧力として測定するロードセル7と、スクリュ3を軸方向に移動させるボールネジ6と、タイミングベルト12を介してボールネジ6を回転させる射出サーボモータ8と、ロードセル7からの信号、および射出サーボモータ8に設けられているエンコーダ9からの信号に基づき、射出サーボモータ8を制御するコントローラ10とを有する。また、電動射出成形機の射出装置は、シリンダ1内に供給された樹脂を溶融しながらスクリュ3を回転させ、前方(図1において左方向)に向けて送り出しながら可塑化するための回転計5を備えた回転サーボモータ4を有する。
【0016】
コントローラ10は、射出速度となるスクリュ3の軸方向の移動速度の速度設定値、射出圧力の圧力制限値、保圧力等を設定する設定部10a、予め求めておいた慣性流れ時昇圧ΔP、限界圧力PL等(慣性流れ時昇圧ΔP、限界圧力PLについては後述する)を記憶しておく記憶部10b、速度設定値と検出速度あるいは射出圧力制限値と検出圧力値とを比較する比較部10c等を備えている。そして、ロードセル7で検出される射出圧力は、不図示の増幅器で増幅され、コントローラ10に入力されるようになっている。射出サーボモータ8の回転速度は、エンコーダ9で検出され、スクリュ3の検出速度としてコントローラ10に入力され、この入力値に基づいて制御される。
【0017】
コントローラ10の記憶部10bには、射出中に異常な状態、例えば、不図示の金型キャビティ内がフルパックされても保圧切換位置に達しないで高速を維持するような間違った成形条件で射出した状態、あるいは充填中にノズル1aや金型ゲートなどの絞られた流路部分で溶融材料の詰まりを生じてしまった状態などが発生したとき、そのときの速度から急制動した時の慣性流れによる射出圧力の慣性流れ時昇圧ΔPが記憶されている。また、記憶部10bには射出装置や金型を破損させない限界値として、限界圧力PL(図2参照)、あるいは、限界圧力PL=射出制限圧力Pa+αとした場合のαも記憶されている。
【0018】
なお、本実施形態では、射出圧力はロードセル7で、そしてスクリュ3の速度はエンコーダ9で検出するようになっているが、これに限定されるものではなく、射出圧力はシリンダ1に圧力センサを取り付けて検出するものであってもよいし、スクリュ3の速度は直接計測するものであってもよい。
【0019】
次に、以上のような構成の本実施形態の電動射出成形機における、射出中に異常な状態が発生した際の射出制御方法に関して説明する。
【0020】
まず、コントローラ10から射出サーボモータ8に対してスクリュ3が設定速度で前進するように信号を送信し、金型キャビティ内に溶融材料を射出する。この際、射出速度および射出圧力Pを常時測定しながら射出を行う(ステップS1)。
【0021】
また、この際、比較部10cにて、射出圧力Pと慣性流れ時昇圧ΔPとの和が限界圧力PLより大きいかどうかを比較演算する(ステップS2)。P+ΔP≧PLとなったとき(この時の射出圧をPmとして図2に図示)、コントローラ10から射出サーボモータ8に急制動信号を送信して射出サーボモータ8に急制動をかけ、射出圧力Pが限界圧力PLを越えて昇圧するのを防止する(ステップS3)。その後、射出制限圧力Paで圧力制御を実行する(ステップS4)。さらに、その後、スクリュ位置が保圧切換位置まで前進したかどうかを判別し(ステップS5)、スクリュ3が保圧切換位置まで前進していなかったら、射出制限圧力Paを保持したまま(図2中、実線)機械を停止する(ステップS6)。スクリュ3が保圧切換位置まで前進したなら、保圧工程に移行(図2中、破線)する(ステップS7)。以上の各ステップにおける射出保圧時間tに対する射出圧力Pの関係は図2に示す通りとなる。
【0022】
一方、ステップS2にて、P+ΔP<PLのときには、さらに、P<Paかどうかを判別し(ステップS8)、P<Paが成立、すなわち、通常の状態では、射出工程における所定の速度制御を実行し(ステップS9)、スクリュ位置が保圧切換位置まで前進したら保圧工程に移行する(ステップS7)。この場合、射出保圧時間tに対する射出圧力Pの関係は、従来と同様、図5に示す通りとなる。
【0023】
また、ステップS8で、P≧Paが成立、すなわち、P+ΔP<PL、かつ、P≧Paが成立する場合には、ステップS4に進み、射出制限圧力Paで圧力制御を実行する。そして、射出制限圧力Paで充填できたらスクリュ3を前進させ、スクリュ位置が保圧切換位置まで前進したかどうかを判別し(ステップS5)、スクリュ3が保圧切換位置まで前進していなかったら、射出制限圧力Paを保持したまま(図2中、実線)機械を停止する(ステップS6)。この場合、射出保圧時間tに対する射出圧力Pの関係は、図4に示す通りとなる。
【0024】
なお、ステップS3で射出サーボモータ8を減速度一定で減速する場合、減速時の任意の速度Vdでの昇圧分ΔPは、ΔP=ΔPmax×(Vd/Vmax)2で求められる。ここで、Vmaxは、最大射出速度であり、ΔPmaxは、最大射出速度時の慣性流れ時の昇圧分である。
【0025】
【発明の効果】
以上説明したように本発明によれば、射出中、常時、射出圧力Pを測定するとともに、P+ΔP≧PLとなるかどうかを判別しながら射出を行い、万一、射出中に異常な状態が生じて限界圧力PLを越えるおそれが発生した時点で射出サーボモータ8の急制動制御を行う。このため、射出中に異常な状態が発生したとしても、射出成形機、あるいは金型に限界圧力PLを越える圧力がかかることがなく、射出成形機、あるいは金型の破損を未然に防ぐことができる。
【図面の簡単な説明】
【図1】本発明の一実施形態である電動射出成形機の構成を示す模式図である。
【図2】射出中に異常な状態が発生した場合の、本発明の射出制御方法による射出圧力の波形の一例を示すグラフである。
【図3】本発明の射出制御方法の一例を説明するためのフローチャートである。
【図4】射出中に、P+ΔP≦PL、かつ、P≧Paが成立した場合の、本発明の射出制御方法による射出圧力の波形の一例を示すグラフである。
【図5】従来の、射出制御方法による射出圧力の波形の一例を示すグラフである。
【図6】従来の、射出中に異常な状態が発生した場合の、射出制御方法による射出圧力の波形の一例を示すグラフである。
【符号の説明】
1 シリンダ
1a ノズル
2 スクリュヘッド
3 スクリュ
3 タイミングベルト
4 回転サーボモータ
5 回転計
6 ボールネジ
7 ロードセル
8 射出サーボモータ
9 エンコーダ
10 コントローラ
10a 設定部
10b 記憶部
10c 比較部
11 軸受け部
12 タイミングベルト
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection control method for an electric injection molding machine in which a molten material in a cylinder is driven by driving an electric motor to advance a screw and injected into a cavity of a mold to form a molded product.
[0002]
[Prior art]
Injection molding in an electric injection molding machine is generally connected to a screw with an electric motor, a mold closing process for closing a mold, a mold clamping process for clamping the mold, a nozzle touch process for pressing the nozzle against the sprue of the mold, and the electric motor. The ball screw is rotated to advance the screw in the cylinder and inject the molten material accumulated in front of the screw into the mold cavity, and then hold pressure to suppress the generation of bubbles and sink marks For the next cycle between the pressure holding process for a while and the molten material filled in the mold cavity is cooled and solidified, the screw is rotated to melt the resin in front of the cylinder. In order to remove the solidified molded product from the mold, the mold is opened and the molded product is pushed out by a protruding pin provided on the mold. Consisting of an open-molded article ejection process.
[0003]
FIG. 5 is a graph showing the relationship between the injection speed V and the injection pressure P with respect to the injection hold time t from the injection process to the pressure holding process.
[0004]
In general, in injection control in injection molding, the screw is advanced at a set speed, and as the filling amount of the molten material into the mold cavity increases with the injection time, the injection pressure P rises, and the mold cavity A method is adopted in which the pressure control is switched from the speed control to the pressure control at the holding pressure switching position just before the molten material filled therein becomes a full pack, and then the holding pressure is applied for a while. Further, the operator generally sets the injection speed and the injection limit pressure so that the injection pressure P does not exceed the injection limit pressure Pa during the speed-controlled injection process.
[0005]
However, abnormal conditions during injection, such as when injection is performed under wrong molding conditions that maintain high speed without reaching the holding pressure switching position even when the mold cavity is fully packed, When clogging of the molten material occurs in the narrowed flow path portion such as a mold gate, the pressure suddenly rises and the injection pressure P reaches the injection limit pressure Pa as shown in FIG. possible.
[0006]
In such a case, in the conventional control method, when the injection pressure P reaches the injection limit pressure Pa, the injection speed V is braked to limit the rise of the injection pressure P, and the injection limit pressure Pa is maintained. Pressure control is commonly applied.
[0007]
[Problems to be solved by the invention]
However, in the electric injection molding machine, when the pressure P during injection approaches the injection limit pressure Pa, the above-described abnormal state occurs, and the injection pressure P rapidly increases to reach the injection limit pressure Pa. If a situation occurs, the electric motor's rotor and screw are rotated around its axis even if the electric motor is suddenly braked and the injection speed V is suddenly decelerated by the above-described control to stop the pressure increase. Because of the inertia of the drive system such as the bearing part that supports the bearing, the ball screw mechanism part that is assembled to the bearing part, and the timing belt, pulley, and screw that transmit the power of the electric motor to the ball screw mechanism part, the screw is slightly Cannot move forward, that is, inertial flow cannot be avoided. The amount of inertia flow of the screw is generally injection speed × deceleration time / 2. At this time, for example, when nozzle clogging occurs, the molten material from the screw tip to the nozzle tip is compressed, causing a pressure increase and injection. The pressure P exceeds the injection limit pressure Pa, and further exceeds the limit pressure P L that does not damage the injection device and the mold, and reaches the abnormal pressure Pb. Further, the pressure increase at the time of deceleration from a certain speed to the speed 0 is generally expressed by the pressure increase at the maximum injection speed × (injection speed / maximum injection speed) 2 . That is, when the injection speed is low, the pressure increase due to the inertia flow is small, so this is not a problem. However, when the speed approaches the maximum injection speed, the pressure increase becomes extremely large pressure. There was a risk of damaging the mold. It should be noted that the injection limit pressure Pa, a limit pressure on the molding quality of such limitations do not damage the mold pressure or size of the molded article, is the pressure to repeatedly acting out of the allowable dimension, a threshold pressure P L Is a single limit pressure that does not damage the injection device or mold in the event of an abnormality.
[0008]
Accordingly, the present invention provides a safe injection control method for an electric injection molding machine in which an injection pressure does not exceed a limit pressure due to an erroneous molding condition or an abnormal pressure increase caused by clogging of a molten material. With the goal.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the injection control method of the electric injection molding machine according to the present invention controls the rotation speed of the injection servo motor that moves the screw via the ball screw based on the forward speed of the screw in the cylinder and the injection pressure. In the injection control method of the electric injection molding machine that controls the injection of the molten material into the cavity of the mold, the deceleration until the screw speed becomes zero after the braking signal is transmitted from the controller to the injection servo motor. The pressure increase ΔP during inertia flow, which is the pressure that rises at times, is obtained in advance, and the value and the limit pressure P L are stored in the storage unit of the controller, and are constantly measured by the load cell during injection at the comparison unit of the controller. and the sum of the injection pressure and the inertial flow at boosting [Delta] P of the molten material in the cylinder which is being is, compared with the threshold pressure P L, the case of P + ΔP ≧ P L, Sunawa , (And Pm the injection pressure at this time) when it reaches the P ≧ P L -ΔP, and characterized in that sending the sudden braking signal to the injection servomotor comprising the step of decelerating the forward speed of the screw until 0 To do.
[0010]
As described above, the injection control method of the electric injection molding machine according to the present invention is such that when an abnormal state that makes injection impossible occurs during injection, the injection pressure of the inertia flow when sudden braking is performed from the injection speed at that time. An increase, that is, a pressure increase ΔP during inertia flow is obtained in advance, and the sum of the pressure increase ΔP during inertia flow and the injection pressure P of the molten material in the cylinder, which is constantly measured by the load cell, is compared with the limit pressure P L. While injecting. In other words, the injection control method of the electric injection molding machine according to the present invention is a pressure increase during the inertia flow of the screw that occurs when the injection servo motor is braked even when an abnormal state occurs during injection. Since the speed of the injection servo motor is controlled in anticipation of the pressure increase ΔP during inertia flow, even if an abnormal condition that prevents injection occurs, the pressure exceeding the limit pressure P L is applied to the injection molding machine or mold. There is no such thing.
[0011]
Further, in the injection control method of the electric injection molding machine of the present invention, when the maximum injection speed is Vmax and the pressure increase at the maximum injection speed is ΔPmax, the pressure increase ΔP at an arbitrary injection speed Vd is A step of obtaining as ΔP = ΔPmax × (Vd / Vmax) 2 may be included.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0014]
In FIG. 1, the schematic block diagram of the injection device of the electric injection molding machine which is one Embodiment of this invention is shown.
[0015]
An injection device of an electric injection molding machine is inserted into a cylinder 1, a screw 3 that is inserted into the cylinder 1 so as to be able to rotate and move forward and backward, and has a screw head 2 at the tip, and one end of a screw 3 opposite to the screw head 2. A load cell 7 that measures the distortion due to the reaction force of the screw 3 at the time of injection as an injection pressure, a ball screw 6 that moves the screw 3 in the axial direction, an injection servomotor 8 that rotates the ball screw 6 via a timing belt 12, And a controller 10 that controls the injection servomotor 8 based on a signal from the load cell 7 and a signal from an encoder 9 provided in the injection servomotor 8. Further, the injection device of the electric injection molding machine rotates the screw 3 while melting the resin supplied into the cylinder 1 and rotates the screw 3 toward the front (left direction in FIG. 1) to plasticize the tachometer 5. The rotary servo motor 4 is provided.
[0016]
The controller 10 includes a setting unit 10a for setting a speed setting value of the moving speed in the axial direction of the screw 3 serving as an injection speed, a pressure limit value of the injection pressure, a holding pressure, and the like. A storage unit 10b for storing pressure P L and the like (pressure increase ΔP during inertia flow and limit pressure P L will be described later), a comparison unit that compares a speed set value with a detected speed or an injection pressure limit value and a detected pressure value 10c and the like. The injection pressure detected by the load cell 7 is amplified by an amplifier (not shown) and input to the controller 10. The rotation speed of the injection servo motor 8 is detected by the encoder 9 and input to the controller 10 as the detection speed of the screw 3 and is controlled based on this input value.
[0017]
The storage unit 10b of the controller 10 has an abnormal state during injection, for example, an incorrect molding condition that maintains a high speed without reaching the holding pressure switching position even if the mold cavity (not shown) is fully packed. Inertia at the time of sudden braking from the speed at the time of injection or when a state in which the melted material is clogged in the narrowed flow path portion such as the nozzle 1a and the mold gate during filling The pressure increase ΔP during the inertial flow of the injection pressure due to the flow is stored. The storage unit 10b also stores a limit pressure P L (see FIG. 2) or α when the limit pressure P L = injection limit pressure Pa + α as a limit value that does not damage the injection device or the mold. .
[0018]
In this embodiment, the injection pressure is detected by the load cell 7 and the speed of the screw 3 is detected by the encoder 9. However, the present invention is not limited to this. It may be attached and detected, or the speed of the screw 3 may be directly measured.
[0019]
Next, an injection control method when an abnormal state occurs during injection in the electric injection molding machine of the present embodiment configured as described above will be described.
[0020]
First, a signal is transmitted from the controller 10 to the injection servo motor 8 so that the screw 3 moves forward at a set speed, and the molten material is injected into the mold cavity. At this time, injection is performed while constantly measuring the injection speed and injection pressure P (step S1).
[0021]
At this time, the comparison unit 10c compares and calculates whether or not the sum of the injection pressure P and the inertia flow pressure increase ΔP is larger than the limit pressure P L (step S2). When P + ΔP ≧ P L (the injection pressure at this time is shown as Pm in FIG. 2), a sudden braking signal is transmitted from the controller 10 to the injection servo motor 8 to suddenly brake the injection servo motor 8, and the injection pressure P is prevented from increasing beyond the limit pressure P L (step S3). Thereafter, pressure control is executed at the injection limiting pressure Pa (step S4). Further, after that, it is determined whether or not the screw position has advanced to the holding pressure switching position (step S5). If the screw 3 has not advanced to the holding pressure switching position, the injection restriction pressure Pa is maintained (in FIG. 2). , Solid line) The machine is stopped (step S6). If the screw 3 moves forward to the holding pressure switching position, the process proceeds to the holding pressure process (broken line in FIG. 2) (step S7). The relationship of the injection pressure P with respect to the injection hold time t in each of the above steps is as shown in FIG.
[0022]
On the other hand, if P + ΔP <P L in step S2, it is further determined whether P <Pa (step S8), and P <Pa is satisfied, that is, in a normal state, a predetermined speed control in the injection process is performed. If it is executed (step S9) and the screw position advances to the holding pressure switching position, the pressure holding process is started (step S7). In this case, the relationship of the injection pressure P with respect to the injection hold time t is as shown in FIG.
[0023]
In step S8, if P ≧ Pa is satisfied, that is, if P + ΔP <P L and P ≧ Pa, the process proceeds to step S4, and pressure control is performed at the injection restriction pressure Pa. Then, if the injection limit pressure Pa can be filled, the screw 3 is advanced to determine whether the screw position has advanced to the holding pressure switching position (step S5), and if the screw 3 has not advanced to the holding pressure switching position, The machine is stopped while maintaining the injection limiting pressure Pa (solid line in FIG. 2) (step S6). In this case, the relationship between the injection pressure P and the injection pressure P is as shown in FIG.
[0024]
When the injection servo motor 8 is decelerated at a constant deceleration in step S3, the pressure increase ΔP at an arbitrary speed Vd during deceleration is obtained by ΔP = ΔPmax × (Vd / Vmax) 2 . Here, Vmax is the maximum injection speed, and ΔPmax is a pressure increase during inertial flow at the maximum injection speed.
[0025]
【The invention's effect】
As described above, according to the present invention, during the injection, the injection pressure P is always measured, and the injection is performed while determining whether or not P + ΔP ≧ P L. The sudden braking control of the injection servomotor 8 is performed at the time when the possibility of exceeding the limit pressure P L occurs. For this reason, even if an abnormal state occurs during injection, pressure exceeding the limit pressure P L is not applied to the injection molding machine or mold, and damage to the injection molding machine or mold can be prevented. Can do.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of an electric injection molding machine according to an embodiment of the present invention.
FIG. 2 is a graph showing an example of an injection pressure waveform according to the injection control method of the present invention when an abnormal state occurs during injection.
FIG. 3 is a flowchart for explaining an example of an injection control method of the present invention.
FIG. 4 is a graph showing an example of an injection pressure waveform according to the injection control method of the present invention when P + ΔP ≦ P L and P ≧ Pa are satisfied during injection.
FIG. 5 is a graph showing an example of a waveform of an injection pressure by a conventional injection control method.
FIG. 6 is a graph showing an example of a waveform of injection pressure according to an injection control method when an abnormal state occurs during injection in the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder 1a Nozzle 2 Screw head 3 Screw 3 Timing belt 4 Rotation servo motor 5 Tachometer 6 Ball screw 7 Load cell 8 Injection servo motor 9 Encoder 10 Controller 10a Setting part 10b Storage part 10c Comparison part 11 Bearing part 12 Timing belt

Claims (2)

  1. シリンダ内のスクリュの前進速度、および射出圧力に基づき、ボールネジを介してスクリュを移動させる射出サーボモータの回転速度を制御して、金型のキャビティ内への溶融材料の射出を制御する電動射出成形機の射出制御方法において、
    コントローラ(10)から前記射出サーボモータ(8)に制動信号を送信してからスクリュ(3)の速度が0となるまでの減速時に上昇する圧力である慣性流れ時昇圧ΔPと、射出成形時の限界圧力PLとを記憶しておき、射出時に、常時測定されているシリンダ(1)内の溶融材料の射出圧力Pと前記慣性流れ時昇圧ΔPとの和と、前記限界圧力PLとを比較し、P+ΔP≧PLとなったとき、前記射出サーボモータ(8)に急制動信号を送信して前記スクリュ(3)の前進速度を0まで減速する工程を含むことを特徴とする、電動射出成形機の射出制御方法。
    Electric injection molding that controls the injection of molten material into the mold cavity by controlling the rotation speed of the injection servo motor that moves the screw through the ball screw based on the forward speed of the screw in the cylinder and the injection pressure In the injection control method of the machine,
    Inertia flow boost ΔP, which is the pressure that rises during deceleration from when the braking signal is transmitted from the controller (10) to the injection servo motor (8) until the speed of the screw (3) becomes zero, and during injection molding The limit pressure P L is stored, and the sum of the injection pressure P of the molten material in the cylinder (1), which is constantly measured at the time of injection, and the pressure increase ΔP during the inertia flow, and the limit pressure P L are determined. In comparison, when P + ΔP ≧ P L is satisfied, it includes a step of transmitting a sudden braking signal to the injection servo motor (8) to reduce the forward speed of the screw (3) to zero. Injection control method of injection molding machine.
  2. 最大射出速度をVmax、最大射出速度時の昇圧分をΔPmaxとしたとき、前記スクリュ(3)の任意の速度Vdからの減速時の慣性流れ時昇圧ΔPを、ΔP=ΔPmax×(Vd/Vmax)2として求める工程を含む、請求項1に記載の電動射出成形機の射出制御方法。When the maximum injection speed is Vmax and the pressure increase at the maximum injection speed is ΔPmax, the pressure increase ΔP during inertia flow when the screw (3) is decelerated from an arbitrary speed Vd is expressed as follows: ΔP = ΔPmax × (Vd / Vmax) comprising the step of obtaining a 2 injection control method for an electric injection molding machine according to claim 1.
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JP2007216449A (en) * 2006-02-15 2007-08-30 Nissei Plastics Ind Co Method and apparatus for monitoring operation state of injection molding machine
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