Importance

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Abstract

An injection molding apparatus and a bushing for use therein. Pressurized molten material flows intermittently from a source through runner channels in a heated manifold and internal lumens in heated bushings for injection through gates into article formation cavities of a mold. Each bushing includes a conically shaped, distalmost section extending substantially centrally into a mold gate. Each bushing also includes a distally opening annular cavity located between its distalmost section and its inner lumen. The annular cavity has outer walls which are substantially parallel to the bushing axis, and inner walls. The inner walls form a distally tapered shoulder having an outer edge and an inner edge. The outer edge extends substantially helically and distally along an axial projection of the proximal portion of the bushing. The inner edge extends substantially helically and distally along an axial projection of the smaller maximum diameter of the conically shaped portion. A portal connects the closed end of the annular cavity formed by the inner and outer walls to the molten material conveying internal lumen. Melt flow facilitation means such as grooves in the shoulders also are provided. The configuration of the annular cavity creates a substantially uniform, distally directed melt flow at its open end for injection into an article formation cavity along the conically shaped distalmost section.

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First Claim