JPH0866944A - Speed control method for injection molding machine - Google Patents
Speed control method for injection molding machineInfo
- Publication number
- JPH0866944A JPH0866944A JP20533094A JP20533094A JPH0866944A JP H0866944 A JPH0866944 A JP H0866944A JP 20533094 A JP20533094 A JP 20533094A JP 20533094 A JP20533094 A JP 20533094A JP H0866944 A JPH0866944 A JP H0866944A
- Authority
- JP
- Japan
- Prior art keywords
- injection
- speed
- pressure
- switching
- screw
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、射出成形機の速度制御
方法に係り、特に射出時のチェック弁の閉り特性のばら
つきの悪影響を最小限に抑制するように配慮した射出成
形機の速度制御方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control method for an injection molding machine, and more particularly to a speed control method for an injection molding machine, which is designed to minimize the adverse effects of variations in the check valve closing characteristics during injection. Regarding control method.
【0002】[0002]
【従来の技術】従来、溶融樹脂の射出成形においては、
図3に示すように、横軸を射出スクリュの位置Sまたは
時間tとし、縦軸を射出スクリュの前進速度Vまたは圧
力Pとし、高速で金型キャビティ内へ溶融した樹脂を充
填する充填工程S1 と、溶融樹脂の充填後に金型キャビ
ティ内樹脂に圧力を加えて成形する保圧工程S2 によっ
て射出制御され、多くの場合、充填工程S1 は油圧回路
の圧力調整弁を高圧に設定し、射出開始からの経過時間
または射出スクリュの前進位置を基準に速度を複数段に
変化させるように流量制御弁の開度を時間経過ととも
に、あるいは射出スクリュのストローク位置に応じて変
化させるように設定し、該流量制御弁の調整により射出
シリンダのピストン、すなわち、射出スクリュの射出速
度を制御し、キャビティ内の樹脂が空気を巻き込まない
程度に高速で溶融樹脂をキャビティ内へ充填するものと
し、溶融樹脂がキャビティに充填された後は流量制御弁
を比較的小さい開度に固定し、圧力調整弁により油圧を
調整する保圧工程S2 とし、この保圧工程S2 は時間経
過に応じてキャビティ内に充填された溶融樹脂に所定の
圧力を加え得るように圧力調整弁の開度を変化させ、キ
ャビティ内で溶融樹脂が冷却されることにより樹脂が収
縮し、製品の形状や寸法がキャビティ形状の寸法に対し
て誤差を生じさせることのないように防止するとともに
製品内部に大きな残留応力が生じないようにしている。2. Description of the Related Art Conventionally, in injection molding of molten resin,
As shown in FIG. 3, the horizontal axis represents the position S or time t of the injection screw, the vertical axis represents the forward speed V or pressure P of the injection screw, and the filling step S for filling the molten resin into the mold cavity at high speed. 1 and injection control is performed by a pressure-holding step S 2 in which pressure is applied to the resin in the mold cavity after molding with molten resin to mold the resin. In many cases, the filling step S 1 sets the pressure control valve of the hydraulic circuit to high pressure. Set so that the opening of the flow control valve is changed over time so as to change the speed in multiple stages based on the elapsed time from the start of injection or the forward position of the injection screw, or according to the stroke position of the injection screw. Then, the injection speed of the piston of the injection cylinder, that is, the injection screw is controlled by adjusting the flow control valve, and the molten resin is melted at such a high speed that the resin in the cavity does not entrap air. Shall fill into the cavity, after the molten resin has been filled in the cavity is secured to a relatively small opening the flow control valve, a pressure-holding step S 2 of adjusting the hydraulic pressure by the pressure regulating valve, the pressure-holding step S 2 changes the opening of the pressure adjusting valve so that a predetermined pressure can be applied to the molten resin filled in the cavity with the passage of time, and the molten resin is cooled in the cavity so that the resin shrinks. The product shape and size are prevented from causing an error with respect to the cavity shape size, and a large residual stress is not generated inside the product.
【0003】一般に充填工程における射出プロセス制御
は、前述したように射出スクリュの検出値が予め設定さ
れた射出速度位置に一致したことによって複数段の射出
速度の制御目標値を切替えていた。図4はこの場合の実
施例を示し、充填工程S1 において3段の速度設定値V
1 、V2 、V3 に切替制御した場合の射出速度Vならび
に圧力Pの変化の状況を示している。ところで、射出に
際して射出スクリュ前方の溶融樹脂が射出スクリュ側へ
逆流することを防止するチェック弁の動作は毎ショット
同じタイミングで作動するわけではなく微妙に異なって
いた。Generally, in the injection process control in the filling process, the control target values of the injection speeds of a plurality of stages are switched when the detected value of the injection screw coincides with the preset injection speed position as described above. FIG. 4 shows an embodiment of this case, in which three speed setting values V are set in the filling step S 1 .
It shows the situation of changes in the injection speed V and the pressure P when the switching control is performed to 1 , V 2 and V 3 . By the way, the operation of the check valve for preventing the molten resin in front of the injection screw from flowing backward to the injection screw side during injection is not always the same at every shot, and is slightly different.
【0004】[0004]
【発明が解決しようとする課題】このように充填工程に
おける複数段の射出速度の変更切替は、これまで稀には
時間切替を行なった例もあるが、大半は射出スクリュが
予め設定された位置に到達したときに切替える位置切替
をすべての変更切替点で実施していた。この場合チェッ
ク弁の閉りが遅れたときには、チェック弁の閉りが早い
ときに比べて、同じスクリュ位置における金型キャビテ
ィ内への樹脂の充填量は逆流が多く起る分だけ少なくな
る。従って、充填工程から保圧工程へ移行するV−P切
替点では、一般に予め設定した圧力切替を実施している
ので、チェック弁の閉りが遅れた場合のショットでは、
V−P切替が行なわれる射出スクリュ位置(以後、V−
P切替位置という)はスクリュ前進限側に近くなる。こ
のようにして、充填工程の最終段の設定速度で制御され
る領域が長くなる。図4から、チェック弁の閉りの早い
ショットAの最終段射出領域SA に比べて、チェック弁
の閉りの遅いショットBの最終段射出領域SB が大きい
ことがわかる。特に、ナイロンのように溶融粘度が低
く、しかも溶融粘度の温度依存性が強い樹脂材料を成形
すると、他の樹脂材料よりもさらに大きくチェック弁の
閉り特性がショット毎にばらつき、その結果としてV−
P切替位置もばらつき、最終段の設定速度で制御される
領域のばらつき幅が大きくなり最終段射出時間のばらつ
き幅も大きくなる。図5は、従来の位置切替における最
終段射出速度時間がチェック弁の閉りのばらつきに起因
してショット毎にばらついている状況を示している。こ
のように、チェック弁の閉りが遅いショットでは、射出
時間が長くなり射出時間が長くなった分だけ金型キャビ
ティ内の樹脂は多く冷却されることになり、金型キャビ
ティ内の流動抵抗が大きくなって、キャビティ内への充
填量が不足し軽量の不良成形品が生じていた。以上のよ
うに、従来はショット毎に異なるチェック弁の閉り特性
のばらつきがキャビティ内樹脂充填量不同を招き、成形
品重量のばらつきやそれにともなう成形品質のばらつき
を惹起していた。As described above, although there are some rare cases where the changeover of the injection speeds in the filling process is performed in the past, in most cases, the injection screw is changed at a preset position. Position changeover was performed at all the changeover change points when the point reached. In this case, when the closing of the check valve is delayed, the amount of resin filled in the mold cavity at the same screw position becomes smaller as much backflow occurs than when the closing of the check valve is early. Therefore, since the preset pressure switching is generally performed at the V-P switching point where the filling process shifts to the pressure holding process, in the shot when the check valve is closed late,
The injection screw position where V-P switching is performed (hereinafter, V-
The P switching position) is closer to the screw forward limit side. In this way, the region controlled by the set speed at the final stage of the filling process becomes longer. From Figure 4, compared to the last stage injection region S A early shot A of閉Ri of the check valve, it can be seen that a large final stage exit area S B of the slow shot B of閉Ri of the check valve. In particular, when a resin material such as nylon having a low melt viscosity and a strong temperature dependence of the melt viscosity is molded, the check valve closing characteristic varies more greatly from shot to shot than the other resin materials. −
The P switching position also varies, the variation width of the region controlled by the final stage set speed increases, and the variation width of the final stage injection time also increases. FIG. 5 shows a situation in which the final stage injection speed time in conventional position switching varies from shot to shot due to variations in closing of check valves. In this way, in shots where the check valve closes slowly, the injection time becomes longer and the resin in the mold cavity is cooled more by the longer injection time, and the flow resistance in the mold cavity is reduced. As the size of the mold becomes larger, the amount of filling in the cavity is insufficient, and a light defective molded product is produced. As described above, conventionally, the variation in the closing characteristics of the check valve, which is different for each shot, causes the resin filling amount in the cavity to be inconsistent, which causes the variation in the weight of the molded product and the variation in the molding quality.
【0005】[0005]
【課題を解決するための手段】以上のような課題を解決
するために、本発明においては、射出スクリュ位置を検
出する位置検出器と圧力検出器と前記位置検出器を介し
て検出した射出ストロークの時間微分値を算出する速度
演算器もしくは射出スクリュの射出速度検出器とを装備
し、かつ、充填工程を複数段の異なる射出速度で射出ス
クリュの速度制御を行なう射出成形機において、チェッ
ク弁閉り判定圧力を予め充填工程の任意点に設定すると
ともに、充填開始後射出圧力が該判定圧力に達したとき
の射出スクリュ位置と予め設定した基準ショットにおけ
る該判定圧力到達時の射出スクリュ位置との差異を演算
記憶しておき、前記複数段の射出速度の変更切替点のう
ち、該判定圧力に達する前の切替は各々予め設定した射
出スクリュの基準変更切替位置で速度切替を行ない、該
判定圧力に達した後の切替に際しては各々予め設定した
射出スクリュの基準変更切替位置に前記差異分を増減し
て修正した射出スクリュ位置による位置切替によって速
度切替を行なうこととした。In order to solve the above problems, according to the present invention, a position detector for detecting the position of an injection screw, a pressure detector, and an injection stroke detected through the position detector. In the injection molding machine that is equipped with a speed calculator that calculates the time differential value of or the injection speed detector of the injection screw and that controls the speed of the injection screw at multiple injection speeds during the filling process, close the check valve. The preset judgment pressure is set to an arbitrary point in the filling process in advance, and the injection screw position when the injection pressure reaches the judgment pressure after the start of filling and the injection screw position when the judgment pressure reaches the preset reference shot. The difference is calculated and stored, and among the switching switching points of the injection speeds of the plurality of stages, the switching before the judgment pressure is reached is based on a preset injection screw reference. The speed is switched at the further switching position, and when switching after reaching the judgment pressure, the speed is switched by the position switching by the injection screw position corrected by increasing / decreasing the difference to the preset reference switching position of the injection screw. Decided to do.
【0006】[0006]
【作用】本発明においては、複数段の射出速度の変更切
替点における速度切替は、すべて予め設定した基準変更
切替位置による位置切替によって行なうものであるが、
充填工程の任意点にチェック弁閉り判定圧力を設定し、
充填開始後に射出圧力がこの判定圧力に達したときの射
出スクリュ位置と予め設定した基準ショットにおける判
定圧力時の射出スクリュ位置の差異を演算記憶してお
く。この判定圧力に達した後の速度切替は前記差異分だ
け、前記の基準変更切替位置を修正した位置で各段の速
度切替を実施する。従って、チェック弁の閉りの遅いシ
ョットは全体的に速度切替位置が差異分だけ遅れ、逆に
チェック弁閉りの早いショットは各速度切替位置とも差
異分だけ早くなり、結局、チェック弁閉りの遅速に関係
なく、最終段射出時間はほぼ一定となり、キャビティ内
充填量は一定に保持されるから、毎ショットとも成形品
品質が安定する。According to the present invention, the speed switching at the plurality of injection speed change switching points is performed by position switching according to a preset reference change switching position.
Set the check valve closing judgment pressure at any point in the filling process,
The difference between the injection screw position when the injection pressure reaches this judgment pressure after the start of filling and the injection screw position at the judgment pressure at the preset reference shot is calculated and stored. After the judgment pressure is reached, the speed switching is performed for each stage at the position where the reference change switching position is corrected by the difference. Therefore, shots with slow closing of the check valve are delayed by the difference in speed switching position as a whole, and shots with fast closing of the check valve are advanced by differences with respect to each speed switching position. Regardless of the slow speed, the final stage injection time is almost constant and the filling amount in the cavity is kept constant, so that the quality of the molded product is stable with each shot.
【0007】[0007]
【実施例】以下図面に基づいて本発明の実施例の詳細に
ついて説明する。図1〜図2は本発明の実施例に係り、
図1は射出成形機における射出制御装置の構成図、図2
は射出プロセス制御を示す特性曲線図である。図1にお
いて、射出成形機100は、ホッパ1を備えた加熱シリ
ンダ2内に射出スクリュ(スクリュ)3が回転自在かつ
前後進可能に配置されており、スクリュ3の後端部には
スクリュ3と連結された連接ロッド4がフレーム7を貫
通し、フレーム7の後端に固設された油圧モータ6によ
って連接ロッド4およびスクリュ3が回転される。ま
た、フレーム7は左右一対の射出シリンダ5のピストン
ロッド5bと連結され、ピストン5aの作動によりピス
トンロッド5b、フレーム7、連接ロッド4および射出
スクリュ3は一体となって往復動できるよう構成され、
射出スクリュ3の位置は、フレーム7に連結されたレバ
ー7aの動きをスクリュ位置検出器30によって測定さ
れる。一方、射出シリンダ5は油圧源10およびこれに
接続する油圧ユニット20と配管で接続されるととも
に、圧力検出器40によりその作動油圧が測定される。
加熱シリンダ2の先端のノズル2aは金型9のノズル口
へ押圧され、キャビティ9aへ加熱シリンダ2内部の溶
融樹脂を供給するよう構成される。射出制御装置50に
は、速度演算部50aと微分器50bと圧力演算部50
cが内蔵され、スクリュ3の位置情報と射出シリンダ圧
の圧力情報が入力され、速度指令および圧力指令が出力
される。射出成形機100の作動について説明すると、
油圧モータ6によって射出スクリュ3を回転することに
よりホッパ1から加熱シリンダ2内に樹脂材料が供給さ
れ、加熱シリンダ2とスクリュ3によって形成される溝
空間を通過する間に樹脂材料は加熱されて溶融し、スク
リュ3前方に蓄えられる。それとともに、スクリュ3は
徐々に後退し、スクリュ3が所定の位置に達すると油圧
モータ6は停止されて計量工程が終了する。次に、射出
シリンダ5近傍に設置されたサーボ弁(図示せず)を制
御して射出シリンダ5に作動油を送り、スクリュ3を前
進させ金型9のキャビティ9a内へ溶融樹脂を射出す
る。射出プロセスの初期の段階ではスクリュ3の前進に
よってスクリュ3前方の溶融樹脂の一部はスクリュ溝を
介して逆流するが、その後はチェック弁8がチェックシ
ート8aに着座して逆流を防止する。チェック弁8がチ
ェックシート8aに着座する動作は、スクリュ3の前進
とそれに伴なうスクリュ前方の溶融樹脂の逆流によるチ
ェック弁前後の圧力差に関係し、そのタイミングはショ
ット毎にばらつく。射出プロセス(充填工程)ではスク
リュ3の射出速度を制御し、保圧プロセス(保圧工程)
では射出シリンダの油圧力、樹脂圧力、金型内圧力のい
ずれか(図1の実施例では射出シリンダ圧を採用する)
の圧力を制御する。Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 relate to an embodiment of the present invention,
FIG. 1 is a configuration diagram of an injection control device in an injection molding machine, and FIG.
FIG. 4 is a characteristic curve diagram showing injection process control. 1, an injection molding machine 100 includes a heating cylinder 2 having a hopper 1, an injection screw (screw) 3 which is rotatably and movably arranged forward and backward. The connected connecting rod 4 penetrates the frame 7, and the connecting rod 4 and the screw 3 are rotated by the hydraulic motor 6 fixed to the rear end of the frame 7. The frame 7 is connected to the piston rods 5b of the pair of left and right injection cylinders 5, and the piston 5a is configured so that the piston rod 5b, the frame 7, the connecting rod 4 and the injection screw 3 can reciprocate integrally.
The position of the injection screw 3 is measured by the screw position detector 30 by measuring the movement of the lever 7a connected to the frame 7. On the other hand, the injection cylinder 5 is connected to the oil pressure source 10 and the oil pressure unit 20 connected thereto by a pipe, and the working oil pressure is measured by the pressure detector 40.
The nozzle 2a at the tip of the heating cylinder 2 is pressed against the nozzle opening of the mold 9 to supply the molten resin inside the heating cylinder 2 to the cavity 9a. The injection controller 50 includes a speed calculator 50a, a differentiator 50b, and a pressure calculator 50.
c is built in, the position information of the screw 3 and the pressure information of the injection cylinder pressure are input, and the speed command and the pressure command are output. Explaining the operation of the injection molding machine 100,
The resin material is supplied from the hopper 1 into the heating cylinder 2 by rotating the injection screw 3 by the hydraulic motor 6, and the resin material is heated and melted while passing through the groove space formed by the heating cylinder 2 and the screw 3. Then, it is stored in front of the screw 3. At the same time, the screw 3 is gradually retracted, and when the screw 3 reaches a predetermined position, the hydraulic motor 6 is stopped and the measuring process is completed. Next, a servo valve (not shown) installed in the vicinity of the injection cylinder 5 is controlled to send hydraulic oil to the injection cylinder 5, and the screw 3 is advanced to inject the molten resin into the cavity 9 a of the die 9. In the initial stage of the injection process, the forward movement of the screw 3 causes a part of the molten resin in front of the screw 3 to flow back through the screw groove, but thereafter, the check valve 8 is seated on the check seat 8a to prevent the backflow. The operation of the check valve 8 seating on the check seat 8a is related to the forward movement of the screw 3 and the accompanying pressure difference before and after the check valve due to the backward flow of the molten resin in front of the screw, and the timing thereof varies from shot to shot. In the injection process (filling process), the injection speed of the screw 3 is controlled, and the pressure holding process (pressure holding process)
Is one of the oil pressure of the injection cylinder, the resin pressure, and the pressure inside the mold (in the embodiment of FIG. 1, the injection cylinder pressure is adopted).
Control the pressure of.
【0008】本発明においては、図2に示すように、充
填工程における複数段の射出速度(図2の実施例では第
1段速度設定値V1 、第2段速度設定値V2 、第3段速
度設定値V3 、最終段速度設定値V4 の4段階)の各々
の射出速度の変更切替を次の手順によって行なう。ま
ず、従来の速度制御方法と同様に、複数段の射出速度の
変更切替は、予め想定した基準ショット(最も正常な射
出状態と思われる切替操作手順を示すショット)におけ
る設定された射出スクリュ3の位置に実際の射出スクリ
ュ3が到達したときに速度切替を実施する、いわゆる位
置切替を行なうものである。しかしながら、図2に示す
ように、基準ショットの想定カーブMに対して、充填開
始直後のチェック弁8の閉り動作のばらつきにより閉り
動作に遅速が生じ、それぞれカーブAやカーブBのよう
にショット毎に少しずつずれた状態となる。そこで、基
準ショットで設定した基準変更切替位置m1 、m2 、m
3 、m4 で位置切替を実施せず、充填工程の任意点にチ
ェック弁閉り判定圧力PJ (図2の実施例では、基準変
更切替位置m1 と基準変更切替位置m2 との間)を設定
し、射出圧力Pが判定圧力PJ に達したときに計測され
た射出スクリュ3の位置と基準ショットの想定カーブM
が判定圧力PJ に達したときの射出スクリュ位置との差
異を演算したうえ記憶しておき、チェック弁閉り判定圧
力PJ に達した以降における各々の基準変更切替位置m
n 、mn+1 、mn+2 、‥‥をそれぞれこの差異分だけ修
正し、それぞれ修正された修正切替位置で速度切替を実
施する。以上のような操作により速度切替を行なうこと
により、たとえばチェック弁8の閉りの遅いショットB
では、判定圧力到達時の差異△S1 だけ、次々に基準シ
ョット想定カーブMより遅れていくことになり、V−P
切替点SC においても、基準変更切替位置m4 より差異
分△S1 だけ遅れた位置でV−P切替が実施されるか
ら、最終段射出速度領域SB はほぼ基準ショットの最終
段射出速度領域SMと等しくなる。逆に、チェック弁閉
りの早いショットAでは差異分△S2 だけ早くV−P切
替が起り、最終段射出速度領域SA はやはりSM にほぼ
等しくなる。以上のように、最終段設定速度が同じであ
るから、最終段射出速度領域SM 、S A 、SB がほぼ同
じであれば最終段射出時間tfは、チェック弁8の閉り
特性のばらつきに左右されずにほぼ同じ値となる。以上
のように速度切替を実施することによって、充填工程初
期にチェック弁の閉り動作が遅れたショットBやチェッ
ク弁閉りの早いショットAにおいても、基準ショットM
と同時に、最終段射出速度領域ならびに最終段射出時間
がほぼ一定に保たれ、その結果、金型キャビティ9a内
へ充填される樹脂量が毎ショット一定に保持されるので
成形品品質が安定する。In the present invention, as shown in FIG.
A plurality of injection speeds in the filling process (in the embodiment of FIG.
1-step speed set value V1, Second stage speed setting value V2, 3rd speed
Degree set value V3, Final stage speed setting value VFour4 steps)
The change of the injection speed is switched according to the following procedure. Well
In the same way as the conventional speed control method,
Change change is based on a previously assumed reference shot (the most normal shot).
In the shot showing the switching operation procedure that seems to be out)
The actual injection screw at the set position of the injection screw 3.
The so-called position that performs speed switching when the vehicle reaches
It is for switching the position. However, as shown in FIG.
As shown in Fig.
Closed due to variation in closing operation of check valve 8 immediately after start
Slow motion occurs, like curve A and curve B respectively
It will be in a state where it shifts slightly with each shot. Therefore,
Reference change switching position m set in quasi-shot1, M2, M
3, MFourInstead of switching the position with, check at any point in the filling process.
Check valve closing judgment pressure PJ(In the example of FIG.
Changeover position m1And reference change switching position m2Between)
Then, the injection pressure P is the judgment pressure P.JIs measured when
Position of injection screw 3 and assumed curve M of reference shot
Is the judgment pressure PJDifference from the injection screw position when reaching
The difference is calculated and stored in memory, and the check valve closing judgment pressure
Power PJEach reference change switching position after reaching m
n, Mn + 1, Mn + 2, ... are each corrected by this difference.
Correct, and execute speed switching at each corrected switching position.
Give. Switching the speed by the above operation
As a result, for example, shot B in which check valve 8 closes slowly
Then, the difference when reaching the judgment pressure ΔS1Only one after another
It will be later than the expected curve M, and VP
Switching point SCAlso, the reference change switching position mFourMore difference
Min △ S1V-P switching is implemented at a position delayed by
, The final stage injection speed area SBIs almost the end of the reference shot
Step injection speed area SMIs equal to Conversely, the check valve is closed
In the quick shot A, the difference is ΔS2As soon as V-P
Change occurs, the final stage injection speed area SAIs still SMAlmost to
Will be equal. As described above, the final stage set speed is the same.
Therefore, the final stage injection speed area SM, S A, SBIs almost the same
If the same, the final-stage injection time tf is the closing of the check valve 8.
The values are almost the same regardless of variations in characteristics. that's all
By performing speed switching like
Shot B or check that the check valve closing operation was delayed during the period
Even in shot A where the valve closes quickly, reference shot M
At the same time, the final stage injection speed range and the final stage injection time
Is kept almost constant, and as a result, inside the mold cavity 9a
Since the amount of resin filled into
Molded product quality is stable.
【0009】つまり、本発明の意図するところは、充填
工程初期に作動するチェック弁8の閉り動作が遅れた
り、あるいは逆に早くなって作動しても、チェック弁閉
り判定圧力PJ を設定した以降における基準速度切替位
置mn では、その途中に設けたチェック弁閉り判定圧力
PJ に到達したときの射出スクリュ位置と基準ショット
における射出スクリュ位置との差異分を演算記憶して、
後続の基準変更切替位置mn 、mn+1 、mn+2 、‥‥で
はこの差異分だけ修正して位置切替することによって、
ショット毎の射出第1速射出時間が異なっても、それ以
降の射出時間、殊に最終段射出時間をほぼ一定とするこ
とによって、キャビティ充填量を一定に保持しようとす
るものであり、ショット毎にばらつきの有るチェック弁
閉止タイミングの違いを最終段射出時間へ反映させない
ようにした。すなわち、射出第1速の初期のチェック弁
閉り動作が早いか遅いかを、判定圧力PJ 時の射出スク
リュの位置で判断しようとするものであり、射出圧力が
判定圧力PJ に達したときに射出スクリュ位置が射出成
形機の後退側にあるショットはチェック弁閉りの早いシ
ョットであり、射出スクリュ位置が前進側にある場合は
チェック弁閉りの遅いショットであることを示し、生じ
た差異分だけ以後の基準変更切替位置を修正して他の射
出時間、とりわけ、最終段射出時間を一定にしようとす
るものである。種々のテストの結果、すべての速度切替
を位置切替とする図5に見られるショット毎の最終段射
出時間のばらつきは、本発明の方法を実施することによ
り、非常に少なくなり、変動幅は運転初期を除いて約2
0%程度に小さくなった。本発明の方法は、特にナイロ
ンのような溶融粘度の温度依存性の強い樹脂材料では、
従来の制御方法では、チェック弁の閉りのばらつきによ
って最終段射出時間がばらつき、この結果として同じV
−P切替圧力PC で圧力制御に移行し、保圧工程に入っ
ても最終段射出時間の長いショットの場合には、金型内
溶融樹脂の温度が低下して粘度が高くなり流動抵抗が増
大するので充填に支障があり、このV−P切替時の全金
型充填量を一定に保つことができず、成形品品質が安定
しないという難点を解消するもので、V−P切替点であ
る基準変更切替位置m4 でも差異分△S1 だけ遅らせた
り、差異分△S2 だけ早めたりすることによって最終段
射出時間がほぼ一定することは既述したとおりであり、
成形品が安定する。In other words, the intent of the present invention is to set the check valve closing judgment pressure P J even if the closing operation of the check valve 8 which operates at the beginning of the filling process is delayed or, conversely, becomes faster. At the reference speed switching position m n after the setting, the difference between the injection screw position when reaching the check valve closing determination pressure P J provided in the middle and the injection screw position in the reference shot is calculated and stored,
In the subsequent reference change switching positions m n , m n + 1 , m n + 2 , ... By correcting this difference and switching the position,
Even if the injection first speed injection time differs from shot to shot, the cavity filling amount is kept constant by making the subsequent injection time, especially the final stage injection time, almost constant. The difference in the check valve closing timing, which has variations, is not reflected in the final stage injection time. That is, it is intended to determine whether the initial check valve closing operation of the first speed of injection is early or late by the position of the injection screw at the judgment pressure P J , and the injection pressure reaches the judgment pressure P J. Occasionally, a shot whose injection screw position is on the backward side of the injection molding machine is a shot with a quick check valve closing, and a shot with an injection screw position on the forward side is a shot with a late check valve closing. It is intended to correct the subsequent reference change switching position by the difference and to make other injection times, especially the final stage injection time, constant. As a result of various tests, the variation in the final-stage injection time for each shot, which is seen in FIG. 5 in which all speed switching is position switching, is significantly reduced by performing the method of the present invention, and the fluctuation range is reduced. About 2 except the initial stage
It became as small as 0%. The method of the present invention, particularly for a resin material having a strong temperature dependence of melt viscosity such as nylon,
In the conventional control method, the final stage injection time varies due to the variation in the closing of the check valve, and as a result, the same V
In the case of a shot in which the pressure is changed to the P switching pressure P C and the final stage injection time is long even in the pressure holding process, the temperature of the molten resin in the mold decreases, the viscosity increases, and the flow resistance increases. Since it increases, there is a hindrance to filling, and it is possible to eliminate the problem that the quality of the molded product is not stable because it is not possible to keep the total mold filling amount constant at the time of V-P switching. As described above, the final-stage injection time is almost constant by delaying the difference ΔS 1 or advancing the difference ΔS 2 even at a certain reference change switching position m 4 .
Molded product is stable.
【0010】なお、図2に示す本発明の実施例では、V
−P切替点SC である基準速度切替位置m4 も前記差異
分を修正した位置切替としているが、V−P切替点SC
では従来技術(図4に例示)のようにV−P切替圧力設
定値PC による圧力切替とすることもできる(ただし、
判定圧力PJ 以外にV−P切替圧力PC を別途に設定し
なければならず、制御も複雑となり煩わしいので、あま
り望ましいものではない)。In the embodiment of the present invention shown in FIG. 2, V
The reference speed switching position m 4 which is the −P switching point S C is also the position switching in which the difference is corrected, but the VP switching point S C
In can also be a pressure switch according to V-P switching pressure setpoint P C as in the prior art (illustrated in FIG. 4) (where,
It is not desirable because the VP switching pressure P C has to be set separately in addition to the judgment pressure P J , and the control is complicated and cumbersome.
【0011】[0011]
【発明の効果】以上述べたように、本発明においては、
すべての射出速度切替を予め設定した位置切替とする従
来の射出プロセス制御に見られるショット毎にばらつく
最終段射出速度領域の長さや時間の不同を極力排除し、
チェック弁の閉り特性のばらつきが起ってもショット毎
の成形品重量のばらつきやそれに起因する成形品品質の
ばらつきを防止できるようになった。従って、成形品品
質が安定し、信頼性の高い運転を継続することができ、
生産性が向上する。As described above, according to the present invention,
Eliminates the difference in the length and time of the final stage injection speed region that varies from shot to shot, which is seen in conventional injection process control, in which all injection speed switching is preset position switching,
Even if the check valve closing characteristic varies, it is possible to prevent the variation in the weight of the molded product from shot to shot and the resulting variation in the quality of the molded product. Therefore, the quality of molded products is stable and reliable operation can be continued.
Productivity is improved.
【図1】本発明の実施例に係る射出成形機の射出制御装
置の構成図である。FIG. 1 is a configuration diagram of an injection control device of an injection molding machine according to an embodiment of the present invention.
【図2】本発明の実施例に係る射出プロセス制御を示す
特性曲線図である。FIG. 2 is a characteristic curve diagram showing injection process control according to the embodiment of the present invention.
【図3】従来の射出制御における実施例を示すグラフで
ある。FIG. 3 is a graph showing an example of conventional injection control.
【図4】従来の射出プロセス制御を示す特性曲線図であ
る。FIG. 4 is a characteristic curve diagram showing conventional injection process control.
【図5】従来の射出プロセス制御における最終段射出時
間のデータを示す説明図である。FIG. 5 is an explanatory diagram showing data of final-stage injection time in conventional injection process control.
1 ホッパ 2 加熱シリンダ 3 射出スクリュ(スクリュ) 4 連接ロッド 5 射出シリンダ 5a ピストン 5b ピストンロッド 6 油圧モータ 7 フレーム 8 チェック弁 8a チェックシート 9 金型 9a キャビティ 10 油圧源 20 油圧ユニット 30 スクリュ位置検出器 40 圧力検出器 50 射出制御装置 50a 速度演算部 50b 微分器 50c 圧力演算部 100 射出成形機 A チェック弁の閉りの早いショット B チェック弁の閉りの遅いショット M 基準ショット P 圧力 PC V−P切替圧力設定値 Pk 保圧設定値 PJ チェック弁閉り判定圧力 V 射出速度 V1 第1段速度設定値(射出第1速) V2 第2段速度設定値(射出第2速) V3 第3段速度設定値(射出第3速) V4 最終段速度設定値(射出第4速) S 位置 S1 充填工程 S2 保圧工程 SA チェック弁の閉りの早いショットにおける最終段
射出領域 SB チェック弁の閉りの遅いショットにおける最終段
射出領域 SM 基準ショットにおける最終段射出領域 m1 基準変更切替位置 m2 基準変更切替位置 m3 基準変更切替位置 m4 基準変更切替位置(V−P切替点) mn チェック弁閉り判定圧力設定以降の基準速度切替
位置 t 時間 tf 最終段射出時間 N ショット数1 Hopper 2 Heating Cylinder 3 Injection Screw (Screw) 4 Connecting Rod 5 Injection Cylinder 5a Piston 5b Piston Rod 6 Hydraulic Motor 7 Frame 8 Check Valve 8a Check Sheet 9 Mold 9a Cavity 10 Hydraulic Source 20 Hydraulic Unit 30 Screw Position Detector 40 Pressure detector 50 Injection controller 50a Speed calculator 50b Differentiator 50c Pressure calculator 100 Injection molding machine A Shot with a quick closing check valve B Shot with a slow closing check valve M Reference shot P Pressure P C V-P Switching pressure setting value P k Holding pressure setting value P J Check valve closing judgment pressure V Injection speed V 1 1st stage speed setting value (1st injection speed) V 2 2nd stage speed setting value (2nd injection speed) V 3 3rd stage speed set value (3rd injection speed) V 4 Final stage speed set value (4th injection speed) S Position S 1 Filling process S 2 Pressure-holding process S A Final-stage injection area for shots with early closing of check valve S B Final-stage injection area for shots with late closing of check valve S M Final-stage injection area for reference shot m 1 Reference change switching position m 2 Reference change switching position m 3 Reference change switching position m 4 Reference change switching position (VP switching point) m n Reference speed switching position after setting check valve closing judgment pressure t time tf final stage injection time N number of shots
Claims (1)
と圧力検出器と前記位置検出器を介して検出した射出ス
トロークの時間微分値を算出する速度演算器もしくは射
出スクリュの射出速度検出器とを装備し、かつ、充填工
程を複数段の異なる射出速度で射出スクリュの射出速度
制御を行なう射出成形機において、チェック弁閉り判定
圧力を予め充填工程の任意点に設定するとともに、充填
開始後射出圧力が該判定圧力に達したときの射出スクリ
ュ位置と予め設定した基準ショットにおける該判定圧力
到達時の射出スクリュ位置との差異を演算記憶してお
き、前記複数段の射出速度の変更切替点のうち、該判定
圧力に達する前の切替は各々予め設定した射出スクリュ
の基準変更切替位置で速度切替を行ない、該判定圧力に
達した後の切替に際しては各々予め設定した射出スクリ
ュの基準変更切替位置に前記差異分を増減して修正した
射出スクリュ位置による位置切替によって速度切替を行
なう射出成形機の速度制御方法。1. A position detector for detecting an injection screw position, a pressure detector, and a speed calculator for calculating a time differential value of an injection stroke detected through the position detector or an injection speed detector of the injection screw. In an injection molding machine that is equipped with and controls the injection speed of the injection screw at multiple injection speeds during the filling process, the check valve closing judgment pressure is set in advance at an arbitrary point in the filling process, and injection is performed after the start of filling. The difference between the injection screw position when the pressure reaches the judgment pressure and the injection screw position when the judgment pressure is reached in a preset reference shot is calculated and stored, and the change switching point of the injection speed of the plurality of stages is set. Among these, the switching before reaching the judgment pressure is performed by switching the speed at the preset change reference switching position of the injection screw, and when switching after reaching the judgment pressure. A speed control method for an injection molding machine, wherein speed switching is performed by position switching according to the injection screw position corrected by increasing / decreasing the difference to a preset reference switching position of the injection screw.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6205330A JP3036672B2 (en) | 1994-08-30 | 1994-08-30 | Speed control method of injection molding machine |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6205330A JP3036672B2 (en) | 1994-08-30 | 1994-08-30 | Speed control method of injection molding machine |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0866944A true JPH0866944A (en) | 1996-03-12 |
JP3036672B2 JP3036672B2 (en) | 2000-04-24 |
Family
ID=16505143
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JP6205330A Expired - Fee Related JP3036672B2 (en) | 1994-08-30 | 1994-08-30 | Speed control method of injection molding machine |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6325954B1 (en) | 1998-06-05 | 2001-12-04 | Toshiba Kikai Kabushiki Kaisha | Method of controlling electric injection unit of injection molding machine |
WO2003106136A1 (en) * | 2002-06-14 | 2003-12-24 | Netstal-Maschinen Ag | Method for injection-molding weight-accurate parts and corresponding injection molding machine |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6724946B1 (en) | 1999-03-26 | 2004-04-20 | Canon Kabushiki Kaisha | Image processing method, apparatus and storage medium therefor |
-
1994
- 1994-08-30 JP JP6205330A patent/JP3036672B2/en not_active Expired - Fee Related
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6325954B1 (en) | 1998-06-05 | 2001-12-04 | Toshiba Kikai Kabushiki Kaisha | Method of controlling electric injection unit of injection molding machine |
WO2003106136A1 (en) * | 2002-06-14 | 2003-12-24 | Netstal-Maschinen Ag | Method for injection-molding weight-accurate parts and corresponding injection molding machine |
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