US 5,136,141 A · Integral sprue bushing assembly

Abstract

A sprue bushing with an integral casing construction which as improved heat transfer characteristics and a method of making the same are described. A cylindrical bushing body having a first, preselected uniform diameter has a cavity formed therein which axially extends within the bushing body for a predetermined length. A bushing inner core which is integral with the bushing casing is formed in the cavity and extends between the two ends of the bushing body. One or more heating elements in the form of coil heaters may be inserted into the bushing body cavity and a thermally conductive material is deposited into the cavity to fill the remainder of the cavity. When filled, the bushing body is heated to melt the thermally conductive material around the heating element(s) to form a unified heater assembly in the annular cavity. A melt runner passage is then drilled through the inner core.

Claims12

Dependent claims

An internally heated sprue bushing assembly having an inlet for receiving pressurized melt and an outlet for the discharge of the pressurized melt, said sprue bushing assembly comprising:

a bushing casing-core element having an integral outer sidewall and an endwall and an elongated inner core, the outer surface of said elongated inner core and the inner surface of said sidewall defining a generally annular compartment within said bushing casing;
at least one heating means disposed within said annular component in surrounding relation to said elongated inner core, said at least one heating means axially extending a preselected length within and occupying a portion of said annular compartment;
a thermally conductive material occupying the remainder of said annular compartment;
and
a melt runner passage in said elongated inner core interposed between and in flow communication with said inlet and outlet of said sprue bushing assembly.

2 more elements

An internally heated sprue bushing assembly having an inlet for receiving pressurized melt and an outlet for the discharge of said pressurized melt, said sprue bushing assembly comprising;

a unitary bushing casing-core element having an integral outer sidewall, an endwall and an elongated inner core, the outer surface of said elongated inner core and the inner surface of said sidewall defining a generally annular compartment extending axially within said bushing casing;
first and second heating means disposed in said annular compartment in surrounding relation to said elongated inner core, said first heating means axially extending a preselected length within said annular compartment and being disposed therein proximate to said bushing outlet end, said second heating means axially extending a preselected length within said annular compartment and being disposed adjacent said first heating means, said first and second heating means occupying a portion of said annular compartment;
a unified mass of highly thermally conductive material occupying the remainder of said annular compartment;
and
a melt runner passage in said elongated inner core interposed between and in flow communication with said inlet and outlet of said sprue bushing assembly.

2 more elements

Dependencies are inferred from the claim text.

Integral sprue bushing assembly

Life of this patent

Integral sprue bushing assembly

Life of this patent

Abstract

Claims12