冷却速度制御による精密射出成形法の開発 第4報 コの字型試験片の変形特性に及ぼす冷却速度の影響

書誌事項

タイトル別名
  • Development of Precision Injection Molding by Cooling Rate Control Part IV Effect of Cooling Rate on Shrinkage Characteristics of U-shaped Products
  • レイキャク ソクド セイギョ ニ ヨル セイミツ シャシュツ セイケイホウ ノ カイハツ(ダイ4ホウ)コ ノ ジガタ シケンヘン ノ ヘンケイ トクセイ ニ オヨボス レイキャク ソクド ノ エイキョウ

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抄録

In order to enhance the accuracy of precision injection molding, the authors proposed the "precision injection molding by cooling rate control" which enhances accuracy by controlling the shrinkage of molded products, and are studying the mechanism for realizing high precision. To date, we have investigated the shrinkage characteristics of cylindrical products, while limiting the scope of our investigations to only shrinkage along the radius. In this study, we extended the scope of investigations to two-dimensional deformations and applied the proposed molding method to U-shaped products. The width W1 at the base and width W2 at the opening of the U-shape were measured, and the effects of the initial mold temperature (TM) and cooling rate on deformations at the side walls of PPS products were investigated. It was found that W1 is easily affected by the effects of in-plane shrinkage of the top board, and more or less the same characteristics as deformation characteristics along the radius in cylindrical products were seen. Rapid cooling was confirmed to be effective for controlling deformation when TM is higher than the glass transition temperature (Tg). In addition, the deformation characteristics of W2, which directly reflect the tilting amount of the side walls, also changed around Tg like W1. When TM was higher than Tg, the side walls were found to tilt inwards in normal cooling, and this could be reduced by uniform rapid cooling. However, in non-uniform rapid cooling, when TM was below Tg, no differences between the cooling methods were seen, however, deformation was found to be most controlled around Tg. When this led to low temperature, the tilting amount of the side walls increased. The same characteristics were seen for PBT and POM. These results also demonstrate that these characteristics can be explained by the generation of thermal stress depending on cooling rate and progress of stress relaxation.

収録刊行物

  • 成形加工

    成形加工 26 (7), 364-373, 2014

    一般社団法人 プラスチック成形加工学会

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