射出成形品の厚さ方向に分布する熱膨張率の推定法
Estimation of Coefficient of Thermal Expansion in the Thickness Direction of Injection Moldings
新保 實・石島 守・山部 昌・宮野 靖
Shimbo, Minoru / Ishijima, Mamoru / Yamabe, Masashi / Miyano, Yasushi
It is necessary to determine the exact material properties in order for analyze the residual stress generated in molds by using theories such as linear viscoelastic and etc. In this paper, a method of estimating the coefficient of thermal expansion which directly effects the residual stress generated in molds was studied based on numerical analysis using a thermoviscoelastic model. The basic equations, which can estimate the distributions of coefficient of thermal expansion in the thickness direction of molds, were derived. Distributions of coefficient of thermal expansion in the thickness direction of polypropylene (PP) resin molded plates were calculated by using the above basic equations and experimental results of residual stress and the coefficient of thermal expansion in arbitrary thickness. By comparing the numerical results and the experimental results, validity of a method of estimation proposed in this paper is discussed.
Key words: Injection molds / Residual stress / Temperature distribution / Thermoviscoelastic model / Coefficient of thermal expansion