| 摘要 |
PURPOSE:To form a hollow part without adversely affecting surface characteristics in the vicinity of a gas channel of a molded item and generating an uneven gloss, esp., on a grained molded item by a method wherein after a hollow area is formed in a molding space filled with an injected melt resin by blowing a gas at a relatively low pressure, a gas is blown at a relatively high pressure. CONSTITUTION:After the start of the charging of a melt resin in a molding cavity by injection, a resin pressure increases along a curve Lp to reach a maximum value Pmax. At approximately the same time, gas blowing is started at a pressure Pg1 lower than a normal value as shown by a curve Lg for forming a hollow part (gas channel) We in a thick-wall part Wa of a molded item W. After a surface layer is set by a predetermined thickness after the elapse of a time Ta, a gas is blown at a normal gas blowing pressure Pg2 for expanding the gas channel Wc in diameter. In this manner, since the gas is blown at the secondary pressure Pg2 after the surface layer is set, the surface layer is prevented from displacing with respect to a molding surface. |
