油電複合式射出單元系統不穩定之改善策略研究

中文摘要使用油電複合式射出成型機(Hybrid Injection Molding Machine)生產高射速(500mm/sec以上)精密元件時，常發生尺寸精度和成品重量不穩定。此乃射出單元於高速射出時產生射出機構的振動或抖動，經生產製程驗證結果，造成射出單元不穩定的成因有射出機構慣性問題、螺桿背壓油路系統殘壓問題及保壓參數曲線調整問題等三大主因。本研究重新設計了射出單元的射出機構並將電動螺桿驅動機構(Electric Screw Drive)移往射出機構的後方固定，且減少1塊活動板元件和縮短4支導柱長度及射出汽缸移動空間縮短簡化使射出單元輕量化。同時設計變更螺桿背壓油路系統，將原先射出回油管共用射出油路板，改良成為單獨獨立回油箱方式，因共用油路板易造成彼此間之壓力干擾。再者，進行保壓曲線參數的校正，依照保壓曲線的壓力命令和實際壓力去調整設定比例積分微分控制器PID增益值，使實際保壓壓力能與命令曲線一致相同。最後，配合統計製程管制表與平均值管制圖分析，做為製程分析追蹤驗證成果的標準，將成果列表分析探討。同時設計上述三種改善策略分別所對應不同條件的實驗，分析比對改善前後的成效。經由本案之設計改良，製程成品的重量誤差由原先1%的不良率降低至0.4%以下之不良率，並且獲得穩定的保壓曲線、射出位置和最前位置。機構慣性對製程噪音污染之影響亦予以減低，輕量化後射出速度可提昇至700mm/sec以上。本研究成果已使其成為商品化並立即導入生產線，以增取市場上的訂單與競爭力。

關鍵字

電動螺桿驅動；機構慣性；螺桿背壓；保壓參數；保壓曲線

並列摘要

ABSTRACT Hybrid injection molding machine is usually used to produce high accuracy component with injection speed above 500mm/sec. Production deficiency and product weight instability were frequently occurred during the production process due to the injection unit shack or vibration. This phenomenon is caused by three main factors of mechanism structure inertia in injection unit, backpressure hydraulic relief system of screw and hold pressure parameter adjustment after practical production verifications. This research redesigns the injection structure of injection unit, by moving fixed point of Electric Screw Drive structure backward for injection structure, removing one moving plate, shortening the length of 4 guide tie bars and minimizing moving space of cylinder. The weight of injection unit is thus reduced. Furthermore, screw backpressure hydraulic system is also redesigned. Hydraulic interferences due to injection relief portion being on same injection manifold block were always encountered in original design system. New design is to make injection relief portion individually and led hydraulic oil back to oil tank. In addition, hold pressure adjustment, SOP, is revised as well, which refers to hold pressure P command and actual pressure in order to adjust PID values of the controller so that the setting and actual hold pressure values can match mutually. Finally, by applying Statistical Production Management and Analysis as evaluation tool for tracing production analysis and the hydraulic oil results will be listed and discussed. Three different trials with specific improving strategies are designed to analyze and compare with before-and-after results. The instable rate of the product weight has decreased from 1% down to 0.4%. Stable hold pressure curve, injection end position and minimum injection position are also acquired. The minimizing mechanical inertia can eliminate production noise pollution and the lightening injection structure can increase injection speed up to 700mm/sec. The results of this research have been made it commercialized and adopted on production line immediately in order to gain more market profitable and competition.