气体辅助注射成型中气道截面对气体穿透的影响

将各种不同气道截面等效于圆形,引入形状因子来衡量它们偏离圆形的程度。利用moldflow软件对气体在不同构型气道内的穿透过程进行了数值模拟。结果表明:形状因子越大则气体穿透深度越大,对气体辅助注射成型有利。但由于形状因子越大则气道截面偏离圆形越远,不利于形成均匀的熔体壁厚,因此在设计气道截面时,应合理选择形状因子以便获得恰当的气体穿透深度和熔体壁厚。最后还给出了气道设计的一般原则。

Effect of Configuration of Gas Channel on Gas Penetration in Gas Assisted Injection Molding

The cross sections of various gas channels were equivalent to circles and the shape factor sf was taken to measure their departure from a circle.The moldflow software package was used for numerical simulation of gas penetration through gas channels with various configurations.The numerical simulation shows that larger sf results in larger gas penetration depth and thus is favorable for gas assisted injection moding.However,larger sf means further departure of the cross section of gas channel from a circle and thus is unfavorable for formation of uniform melt wall thickness.Therefore,sf should be selected rationally so as to result in desired arrangement of gas penetration depth and melt wall thickness.Some general principles are put forward for design of gas channel.