Abstract
This paper describes the influence of molding conditions on residual stress in injection molds. Polypropylene (PP) resin plates are molded under various molding conditions which changed dwelling, injection speed and molding temperature. First, the fundamental equations for residual stress are derived using a thermoviscoelastic model and the generation mechanism of residual stress is explained qualitatively. Second, the thermoviscoelastic properties of PP resin plates which have a direct effect on the residual stress are carefully measured. Finally, the residual stresses in PP resin plates are measured by a layer-removal method and are calculated by using fundamental equations considering thermoviscoelastic properties. By comparing these residual stresses under various molding conditions with the thermoviscoelastic properties mentioned above, the influence of molding conditions on generation mechanism of residual stress in injection molds is discussed.
