SPRUE BUSHING OF MOLDING DIE

• Main Authors: AZUMA KEIJI, NAKADA MASAAKI, SHIMODA KAZUHIKO, KOBAYAKAWA MASUNORI
• Format: Patent
• Language: English
• Published: 29.05.1989
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

PURPOSE:To enhance the cooling effect of a molding cavity and the production efficiency of molding by a method wherein a heat insulating space part is made near the nozzle contact portion of a sprue bushing. CONSTITUTION:At the center of a sprue bushing 1, a trumpet-shaped pouring hole 4, which communicates to a molding cavity 13, is bored and, in addition, a practically hemispherical indented part 6 is made at the opening edge 5 of the pouring hole 4. A heat insulating space part 3 such as four holes 3a are bored at equal angular intervals of 90 deg. along a circumferential line near the circumferential line, at which a nozzle 2 comes into contact with the spherical surface of the indented part 6. In the sprue bushing 1 having the above- mentioned constitution, the air layer is formed between the nozzle 2 and the sprue bushing 1, resulting in generating the heat insulating effect and the reduction of heat transfer area. Accordingly, said heat insulating space part 3 can suppress the heat transfer from the high temperature nozzle 2 to a mold and reduce the heat transferred to the mold, resulting in allowing to enhance the cooling efficiency of the mold.