초록 ▼

Apparatus for thermal gated injection molding having a cavity forming insert separate from the heated nozzle. The cavity forming insert has a combination of heating and cooling extending around a central melt bore leading to a gate. The cavity forming insert has an integral electric heating element

Apparatus for thermal gated injection molding having a cavity forming insert separate from the heated nozzle. The cavity forming insert has a combination of heating and cooling extending around a central melt bore leading to a gate. The cavity forming insert has an integral electric heating element with an inner portion having a number of adjacent coils near the gate. Power to the heating element is switched on and off during the thermal gated cycle, and the combination of heating and cooling in the cavity forming insert improves the thermal response and shortens the cycle time.

대표청구항 ▼

In an injection molding apparatus to convey pressurized melt from a source to a cavity having a cooled cavity forming insert with a rear end, a heated nozzle with a forward end, the heated nozzle being received in a nozzle plate with the forward end of the heated nozzle abutting against the rear end

In an injection molding apparatus to convey pressurized melt from a source to a cavity having a cooled cavity forming insert with a rear end, a heated nozzle with a forward end, the heated nozzle being received in a nozzle plate with the forward end of the heated nozzle abutting against the rear end of the cavity forming insert, the nozzle having at least one melt passage extending therethrough, the improvement wherein; the cavity forming insert has a gate leading to the cavity, a central bore to convey melt from the melt passage in the nozzle to the gate, and an integral electrically insulated heating element, the heating element having an outer terminal portion extending outwardly to an external terminal and an inner portion having a generally uniform rectangular cross section, the inner portion of the heating element having a plurality of adjacent coils which form an inner surface, the heating element being integrally mounted in the cavity forming insert with the inner portion extending around the central bore leading to the gate whereby at least part of the inner surface formed by the adjacent coils of the inner portion of the heating element form a tapered portion of the central bore leading to the gate.