| 摘要 |
PURPOSE:To mold polyester resin products without whitening continuously by a method wherein a spool section having a specified structure and a gate heater synchronized with the cycle of molding are provided in an external heating system hot runner mold. CONSTITUTION:An external heating heater 7 is provided at the outer periphery of a hot runner block 6 and the gate heater 8 heating the outside of the gate mainly is arranged at the gate 9, on the other hand, the spool section 15 consisting of a spool 2 (disposed in the hot runner block 6 and having a length of 5mm. or less and a diameter of 1.2mm. or more) and a spool 3 (disposed in a cavity plate 11 and having a length of 3mm. or more and a diameter of 1.2mm. or more) is provided between a resin flow path 5 and a product section 12. (numeral 4 shows an opening and closing pin, 10, 13 show cooling holes and 14 shows an overcooling preventing groove). The molding work for the polyester resin is effected under heating in a condition that the gate heater 1 is synchronized with the cycle of the molding (for example, the electric power is supplied simultaneously with the closing of the mold and the supply of the same is stopped at a time when an injection process is shifted to a cooling process) by employing the above-described device. |
