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油壓塑膠射出成型機之保壓暨入料背壓控制性能研究 / A Study on the Holding Pressure & Feeding Back-Pressure Control for Hydraulic Plastic Injection Molding Machine

Authors
  • Chen, Jen-Te
Publication Date
Jul 27, 2017
Source
FirstTech Institutional Repository
Language
Chinese
License
Unknown

Abstract

[[abstract]]射出成型過程中射壓、射速、射溫、鎖壓、進料量等各項因素皆會對射出成型品質有相當影響。為了深入研究影響因素眾多且複雜的成型特性,本研究首先建立模型以了解塑膠射出成型運作中各項因素的動態行為,模型的建立並可與實機驗證對照而確保控制系統設計的切實性。本研究特針對射切保之壓力轉換、後段保壓及入料背壓之控制性能進行探討與提出改進方式,傳統控制上使用者設定每段的螺桿位置、射速、保壓、背壓以及入料轉速,系統根據設定值之螺桿位置及時間由原狀態立即切換至下個階段,除了切換猛烈,亦導致射切保壓力產生凸波或凹陷之不平順現象,且入料終點不精準而影響滿模點穩定性。本研究在射切保之壓力轉換上,依使用者之設定滿模點為基準點,預留前一距離做速度減速,當壓力達上限轉平時加入壓力控制迴路平順銜接至第一段保壓壓力,在後段保壓命令規劃上,階梯式降壓方式本研究經模擬發現期間膠料仍會流進流出,因此從第一段保壓結束,後段保壓以無段等斜率降壓方式之命令規劃;入料背壓上,射出油壓缸持續維持背壓,入料馬達依S曲線上升至設定值維持等速,當射出油壓缸退後至入料終點前一定位置,入料馬達依距入料終點之距離減速至最低轉速,最後當射出油壓缸退後至入料終點,入料馬達立即停止,此時射出油壓缸會維持背壓,而精準停止於入料終點。關鍵字:射切保轉換、無段保壓、入料背壓 / [[abstract]]Intheinjectionmoldingprocess,theinjectionpressure,theinjectionvelocity,theinjectiontemperature,theclampingforce,thefeedingquantityandotherfactorswillhaveinfluenceonthequalityoftheinjectionmolding.Inordertostudythecomplicatedformingcharacteristics,firstly,weestablishthemoldingprocessmodeltounderstandthedynamicbehavioroftheplasticinjectionmoldingoperation.Theestablishedmodelcanbefurtherverifiedwiththerealmachinetoensurethecontroldesign.Inthisresearch,westudythecontrolperformanceoftheinjection-holdingtransition,holdingpressureandthefeedingback-pressure.Basedonthosestudiessomeimprovingmethodswereproposed.Fortheinjection-holdingtransitioncontrol,theinjectionscrewpositionisdeceleratedbeforetheinjectionendingpoint,andwhenthepressureturnsflatthesystemswitchtopressurecontrolloopwithS-curvesmoothlychangingthepressuretothefirstsectionholdingpressure.Fortheholdingpressurecontrol,constantpressurewithprecisetimeperiodwascontrolledforthefirstsectionpressurecontroltomakethemoldpreciselypacked.Afterthat,asmoothlydeclinedholdingpressurecontrolwasproposedtopreventtheplasticsflowin/outofthemoldduringthecoolingstage.Forthefeedingbackpressurecontrol,theinjectionhydrauliccylindercontinuestomaintainbackpressure,andthefeedingmotorrisesthespeedtothesetvaluewithS-curveandmaintainsconstantspeedthereafter.Whentheinjectionhydrauliccylinderreachestothepointbeforetheendfeedingpositionwithacertaindistance,thefeedingmotordeceleratestotheminimumspeedlinearlyaccordingtothedistancetotheendfeedingposition.Finally,whentheinjectionhydrauliccylinderreachestheendfeedingposition,thefeedingmotorstopsimmediately.Atthispoint,theinjectionhydrauliccylinderwillmaintainthebackpressure,anditwillbestoppedpreciselyattheendfeedingposition.Keyword:injection-holdingtransition,smoothlydeclinedholdingpressure,feedingback-pressure

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