| 摘要 |
This invention relates to an improved heater cast used in multi-cavity hot runner edge gate injection molding. The improved heater cast enables products to be molded of considerably lower heights than was previously the case and as well facilitates the molding of difficult heat sensitive materials such as PVC, polycarbonate, polyester and acetal resins. The improved heater cast has a cylindrical mid portion with four spaced cylindrical lower nozzle portions extending downwardly around the periphery therefrom. The hot melt flows downwardly from the molding machine, through a central injection passage in the heater cast and branches into four injection passage extensions to the respective gates and cavities. The provision of the four lower nozzle portions enables the cavity plate to have a raised table portion therebetween which provides additional strength and cooling. The provision of a cylindrical mid portion enables an extruded cylindrical TEFLON glass filled insulation sleeve to be located between it and the surrounding cavity plate to facilitate faster color and material changes without streaking problems and to be a permanent insulator against heat loss to the cavity plate.
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