模温及熔体温度对不同材料的薄壁注塑制品熔接痕的影响

Effect of Mold and Melt Temperature on Weld Lines of Thin Wall Injection Molded Parts

利用MoldFlow模拟了不同模温和熔体温度对结晶型聚合物PP、无规脆性聚合物PS、无规韧性聚合物PC成型的数码电视机支撑座熔接痕长度的影响。模拟结果表明:当模具温度低于材料的熔化温度时,升高模具温度能显著的缩短PP、PC熔接痕的长度,但不能明显的缩短PS熔接痕的长度;当模具温度升高到PS熔融温度时,PS熔接痕长度随模温的升高急剧缩短;当模具温度高于熔体注射温度时,熔接痕长度的改变量很小。升高熔体温度不能缩短PP熔接痕长度,能缩短PS、PC熔接痕长度,但熔体温度对熔接痕的影响远不如模温明显。升高模温和熔体温度都很难消除熔体以头-头的形式相遇形成的熔接痕。

The effects of mold and melt temperatures on weld line lengths on digital TV underprop of polypropylene （PP）, polystyrene （PS）, and polycarbonates （PC） were studied by simulation using MoldFlow software. It was found that when mold temperature was lower than polymer＇ s flow temperature, weld line lengths for PP and PC were sharply shortened with increasing mold temperature, but the weld line lengths of PS were not shortened obviously. When the mold temperature was higher than flow temperature of PS, weld line lengths of PS were shortened rapidly with increasing mold temperature. When the mold temperature was higher than melt injection temperature, no apparent change in weld line length was observed. By raising melt temperature, weld line lengths for PS and PC could be shortened, and yet the effect was much less obvious compared with increasing mold temperature. When melts met head-to-head, it was difficult to eliminate weld line by either increasing mold temperature or melt temperature.