Method for applying a differential heating to injection nozzle

• US 6,045,742 A
• Filed: 08/28/1998
• Issued: 04/04/2000
• Est. Priority Date: 08/21/1996
• Status: Expired due to Term

• Current Assignee: Caco Pacific Corporation
• Original Assignee: Caco Pacific Corporation
• Inventors: McGrevy, Alan N.
• Primary Examiner(s): HEITBRINK, JILL LYNNE
• Application Number:
  US09/141,937
• Time in Patent Office: 585 Days
• Field of Search: 425/549, 264/328.15
• US Class Current: 264/328.15
• CPC Class Codes: B29C 2045/274 Thermocouples or heat sensors
• CPC Class Codes: B29C 2045/2777 Means for controlling heat flow or temperature distribution in the nozzle
• CPC Class Codes: B29C 45/2737 Heating or cooling means therefor B29C45/7331 takes precedence

Abstract

This invention provides an improved heating apparatus for controlling the temperatures of the resin melt that is pressure fed to a molding cavity comprising a heating jacket 30 comprising the concentric tubular elements; a copper sheath 32 having an inside surface 34 and an outer surface 36, a retainer sleeve 40 and coiled heating element 42 sandwiched between the sheath 32 and the retainer sleeve 40. The inside surface of the sheath 32 is formed with at least one circumferential groove 38 which provides an insulating air gap so that a lesser amount of heat is conducted to the central portion of the heating jacket 30 thereby creating three distinct temperature zones. The sheath 32 is provided with a channel 46 extending longitudinally down its inside surface 36 between the heating coil 42 and the outside surface of the housing 22 for the hot runner conduit 24. A thermocouple sensor cable 52 is received in the channel so that the thermocouple sensor 50 is strategically positioned adjacent the gate well section 28 to maintain the temperature of the resin melt entering the cavity.

Claims

1. A method for applying a differential pattern of heating zones to a resin material for injection into a mold cavity as it passes through an injection nozzle, said method comprising the steps of:

providing a conduit for feeding resin melt through an injection nozzle body along a feed path directed to a mold cavity;

wrapping the injection nozzle body with a continuous coil winding of heating elements;

distributing the heat from said coiled heating elements uniformly by interposing a heat conductive sheath between the coiled heating elements and the injector nozzle body;

forming a series of heat insulting circumferential grooves along the inside surface of the sheath that is in heat conductive contact with the injector nozzle body, said grooves extending generally normal to the feed path of the resin melt;

whereby a differential pattern of heating zones is applied to the resin melt.

2. The method as claimed in claim 1 wherein a heating zone midway along the feed conduit applies less heat to the resin than the adjoining zones.

3. A method for applying a differential pattern of heating zones to a resin material for injection into a mold cavity as the resin passes through an injection nozzle, said method comprising the steps of:

providing a feed conduit for feeding resin melt through an injection nozzle body directed to a mold cavity;

feeding a supply of resin melt to an injection nozzle body;

forming an uninterrupted winding of heating elements creating a uniform heat pattern about the nozzle body;

conducting the uniform heat pattern from said coiled heating elements by interposing a heat conductive cylindrical sheath between the coiled heating elements and the injection nozzle body;

providing a surface of the sheath against the injection nozzle body, said surface having formed therein a series of heat insulting circumferential grooves;

whereby a differential pattern of heating zones is applied to the resin melt.

4. The method as claimed in claim 3 including the step of forming said circumferential grooves so that the differential pattern is applied normal to the passage of the resin melt.