Kona Corporation

Paul M Swenson

William J Hume

Richard D Devellian

Michael Lewis Vasapoli

A system and apparatus for injection molding articles of crystallizable polymeric materials in a substantially completely amorphous state is provided. The system includes (i) a mold defining an article formation cavity and an outer cavity connected by a gate, (ii) a melt transport mechanism including a bushing having a distal portion located in the outer cavity in close proximity to the gate inlet, and (iii) a source of molten material. The geometric configurations of the distal portion of the bushing, the inner portion of the outer cavity and the gate, and the relative locations of the distal end of the bushing and the inlet of the gate are each selected such that melt material may flow from the source through the melt transport mechanism and gate into the article formation cavity. The melt transport mechanism is maintained at a temperature above the characteristic crystal melt temperature of the polymeric material. The mold temperature is maintained well below the minimum characteristic glass transition temperature of the polymeric material. Further, the geometric configuration of the elements is selected such that the vestige which protrudes from the completed article has a minimum length, and such that during the interval between successive cycles only a small volume of melt located between the discharge orifice of the bushing and the outlet of the gate is allowed to crystallize.

System and apparatus for injection molding articles of amorphous

For open bore injection molding, the apparatus includes in combination a hot bushing, a cold mold, and a thin-walled seal. The bushing is adapted to convey molten material from a hot manifold to an article formation cavity in the mold. The mold defines a bore extending into its upper surface, and a gate at the bottom of the bore which communicates with the article formation cavity. The bushing at least partially fits within, and in spaced relation to, the periphery of the bore. The bushing includes an unobstructed lumen therethrough which opens into its lower end and is generally aligned with the gate. The bushing also defines a depressed portion in its outer surface located in closely spaced, circumferential relation to the opening of the lumen into its lower end. The thin-walled seal is formed of metallic material having low thermal conductivity, and has a generally arc-shaped cross-section. Further, the seal engages the depressed portion of the outer surface of the bushing, and has a small portion compressively urged against the surfaces defining the bore when the bushing is located in the bore. The seal closes off the gap between the bushing and the mold, while at the same time minimizing the conduction of heat therebetween.

Open bore injection molding apparatus

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.

Bushing tip for injection molding apparatus

Apparatus for injection molding articles of amorphous polyethylene

A hot manifold system for use in the injection molding of plastics is disclosed wherein runner channel heating is accomplished by heat pipes disposed within the manifold adjacent to the runner channels contained therein. The manifold system is an elongated structure having a heat receiving portion and a runner containing portion such that heat input may be applied to the heat receiving portion at an accessible location relative to the mold and conveyed to the remainder of the manifold for uniform heating thereof by the heat pipes.

Heat pipe manifold system

An extruder barrel of a thermoplastic molding machine connected to an injection molding nozzle provided with a plurality of heat pipes distributed around the central bore of the nozzle, each of the heat pipes deriving its thermal input from the extruder barrel itself.

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Hamilton, MA, United States of America

Paul M Swenson