Abstract: A plastic injection molding and auxiliary device used for processing articles of high gloss surface without weld lines and flow marks were studied. Surface defects of product were eliminated because the mold temperature changed with the injection molding action; high gloss surface of articles was made because the special channel design of mold could quickly raise the mold cavity temperature above the softening point. The design methods for the channels, materials, and temperature measurement points of the stream heating mold were analyzed. The component parts, the control theory, and the selection calculation method for the corresponding heating auxiliary control device were discussed. The system was verified through the actual production and application. It showed that the system could manufacture plastic products with high gloss surface and without weld lines and flow marks. The system could reduce processing costs and environmental pollution for eliminating spraying process. Injection molding cycle time was reduced from 120 s to 43 s.

Key words: mold, molding cycle, injection molding, high gloss surface, weld line, steam hearing, auxiliary control device