射出成形问题解决方法.pptVIP

* * * * * * * * * * * * * * * * * * * * * * Sink Mark /凹陷痕 Balanced design of Boss/平衡式boss設計 * Corner ( 轉角) Good design (較佳設計) Incorrect design (不良設計) Generous radius (圓弧半俓) Uniform wall thickness (均一壁厚) Smooth flow transition (流動平順) Stress concentration Sharp flow restriction (流動不順, 應力集中) Non-uniform wall thickness Shrinkage/void/sinks Non-uniform flow (非均一壁厚, 衍生翹曲/ 包封/凹陷/流動不順問題) Non-uniform wall thickness shrinkage/void/sinks Non-uniform flow (非均一壁厚, 衍生翹曲/ 包封/凹陷/流動不順問題) * Design for Assembly (組裝設計) Improving both product quality and reducing manufacturing cost (改善成品品質和降低生產成本) Press fit assembly (扣壓式組合) Self fit assembly - Snap Joint (自動式組合-連接卡筍) Mechanical Fastening techniques – Screws (機械固定技術 – 螺絲) Welding techniques (結合技術) Adhesive bonding (黏著性結合) Solvent bonding (溶劑結合) * Design for Assembly (組裝設計) Snap Joint assembly (組裝連接卡筍須符合組裝和拆除的需求) satisfy both Design for assembly and Design for disassembly Simple Most versatile means of plastic product assembly 利用簡易而通用的塑膠成品來組裝 Insertion 崁入 Deflection 偏差 Elastic recovery 彈性回覆 R ?R Lead-in angle (?) 導入角度 * Snap Fit Assembly (卡筍組裝設計) Snap Joint assembly (連接卡筍設計) L R d y Cantilever snap beam (懸臂樑卡筍) constant rectangular cross section (固定長方形橫截面) d d/2 Tapered cantilever snap beam(傾斜式懸臂樑卡筍) decreasing depth from d to d/2 (‘降低深度由d到d/2) y = 0.67 ? L2/d y = 1.1 ? L2/d ? = maximum tensile strain (最大張力) Permissible deflection for the tapered beam is about 60% greater than that of the constant cross section of rectangular beam (對於傾斜式懸臂樑比長方形允許變形度大約大60%) * Snap Fit Assembly (卡筍組裝設計) Snap Joint assembly (連接卡筍設計) Stress concentration at the corner Deflection Neutral axis + ? - ? R T Applied Load 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.0 1.5 2.0 2.5 3.5 3.0 Radius/wall thickness (R/T) Stress concentration factor Stress concentration factors show that larger radius values tend to reduce the stress concentration and mold filling orientation related problems, however, excessive radii can lead to complications d