Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2721
標題: 具內螺紋塑膠瓶蓋之射出成型
Injection Moulding of a Plastic Bottle Cap with Inner Screw Thread
作者: 李清貴
關鍵字: shrinkage;收縮率;injection mold;melting temperature;脫模;熔膠溫度
出版社: 機械工程學系
摘要: 
摘要
此論文包含設計與製作完成一組具內螺紋瓶蓋之模具,並以低密度聚乙烯(LDPE)與聚丙烯(PP)為膠料,在射出成型機上,將膠料射出至模具內成形,藉以探討在不同螺牙深度與節距下,對成形收縮率的影響,同時測試出LDPE與PP之(膠溫、射出速度與射出壓力)成形操作條件之範圍。實驗中共使用四支不同牙深與節距之螺桿心軸( 0.74.8mm,1.054.8mm,1.44.8mm,0.73.5mm),所設定的三種熔膠溫度分別為205℃、220℃、235℃,模具溫度分別為30℃、45℃與60℃,四種保壓力分別為860、960、1060與1160( kg/cm2),在此個別之定溫與定壓下,量測膠料於各狀態成形時,成形收縮率的變化影響與所需之最低與最高有效射出壓力與射出速度值的分佈狀態(P-V曲線),以期能有效地運用在LDPE與PP類膠料的射出成型上。對成形收縮率而言,實驗所得之結果顯示螺牙深度對瓶蓋成形收縮率的影響較節距對其之影響為大,且隨著螺牙深度愈深瓶蓋壁厚成形收縮率愈大,而瓶蓋內徑之收縮率則愈小;研究中並以熔膠溫度、模具溫度與保壓壓力為函數下,利用數值迴歸分析法分別歸納出在三種不同牙深的情況下,對瓶蓋壁厚與瓶蓋內徑成形收縮率影響之運算式。本論文中同時討論四種常應用於生產具有內螺紋瓶蓋的模具之設計,主要探討各種方法之優劣點。本實驗所使用之模具,係採用鏈條鏈輪的脫模方式設計、製造而成。
關鍵字:熔膠溫度,收縮率,脫模,聚乙烯,聚丙烯。

ABSTRACT
The technique of formation and unscrewing of a bottle cap with inner-thread in an injection mold is studied. The shrinkage of the bottle cap from injection molding with various packing pressures, mold and melting temperatures is analyzed. Two plastic materials, low density polyethylene (LDPE) and polypropylene (PP), are used in tests. Three plastics melting temperatures, 205℃,220℃ and 235℃, are considered. The minimum and maximum effective injection pressures and velocities are obtained and the results are represented on a P-V diagram. The optimum operating range is indicated. In the shrinkage analysis, the mold temperature individually is controlled at 30℃,45℃ and 60℃.The packing pressure is in the range 810 kg/cm2 to 1160 kg/cm2. The effects of pitch and screw thread depth on height, wall thickness, inner and outer diameters of the cap are investigated for various packing pressures, mold and melting temperatures. The measured shrinkage data of cap inner diameter and thickness are individually correlated in a polynomial equation. Four conventional devices for unscrewing of bottle cap in inner-thread die are discussed. The mold used in experiment is equipped with a chain-to-chain wheel unscrewing mechanism.
keywords : melting temperature, shrinkage, injection mold, polyethylene, polypropylene。
URI: http://hdl.handle.net/11455/2721
Appears in Collections:機械工程學系所

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