Injection molding nozzle having a centering bushing

摘要

The injection nozzle has a thin-walled centering bushing inserted between the tip insert and the mold insert. The centering bushing engages a shoulder of the mold insert and thus achieves a mutual centering and sealing of the tip insert and the mold insert. This avoids the inflow of molding material into the cavity between the tip insert and the mold insert which would impair or delay the changing of colors of the material, and the injection needle is effectively centered so that a cylindrical tip portion can close a very short cylindrical portion of a gate bore. The heat transfer between the heated nozzle parts and the mold insert is nevertheless maintained at a low level since the mutual centering is obtained by narrow contact sites.