US 4,680,001 AGranted

Passive mold cooling and heating system

AssigneeApplication Engineering Corporation

InventorMichael A. Waters

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Abstract

A mold for molding articles of plastic or other like materials, having a plurality of vertically extending internal passages, is connected by inlet and return conduits into a closed loop that includes a heat exchanger partially filled with a liquid supply of a cooling fluid or a heating fluid. For cooling the heat exchanger is positioned with its liquid level above the top of the mold, the inlet conduit connects the lower part of the heat exchanger, below the liquid level, to the lower ends of the mold passages, and the return conduit connects the upper ends of the mold passages to the upper part of the heat exchanger; for heating these relationships are reversed. In operation the fluid changes its physical state at critical points in the mold passages, going from liquid to vapor for cooling and from vapor to liquid for heating; circulation in the closed loop is in response to the effect of gravity. Operation of the heat exchanger is controlled to maintain a controlled pressure in the closed loop.

Claims11

Dependent claims

A passive cooling system for cooling a mold for molding articles of plastic material without substantial pumping, the mold including a plurality of vertically extending internal passages for passing a cooling fluid through the mold, the system comprising:

a condenser heat exchanger partially filled with a supply of cooling fluid in a liquid state, the cooling fluid constituting a fluid which changes from its liquid state to its vapor state in response to temperatures occurring in critical portions of the mold passages during operation of the mold, the heat exchanger being positioned so that the upper level of liquid fluid in the heat exchanger is approximately at or above the tip of the mold;
an inlet conduit connecting the heat exchanger, from a point below the upper level of the fluid, to the lower ends of the mold passages;
a return conduit connecting the upper ends of the mold passages back to the heat exchanger;
the heat exchanger, the mold passages, and the inlet and return conduits constituting a closed loop;
and heat exchanger control means for controlling operation of the heat exchanger to maintain a controlled pressure in the loop while condensing vaporized fluid back to its liquid state as the fluid returns from the mold to the heat exchanger;
the heat exchanger control means including means to adjust the controlled pressure to establish a minimum limit temperature for cooling of the mold and means for actuating the heat exchanger to vary the loop pressure in synchronism with the molding cycle.

3 more elements

A passive heating system for heating a mold for molding articles of plastic material without substantial pumping, the mold including a plurality of vertically extending internal passages for passing a heating fluid through the mold, the system comprising:

an evaporator heat exchanger partially filled with a supply of heating fluid in a liquid state, the heating fluid constituting a fluid which changes from its vapor state to its liquid state in response to temperatures occurring in critical portions of the mold passages during operation of the mold, the heat exchanger being positioned so that the upper level of liquid fluid in the heat exchanger is approximately at or below the bottom of the mold;
an inlet conduit connecting the heat exchanger, from a point above the upper level of the fluid, to the upper ends of the mold passages,
a return conduit connecting the lower ends of the mold passages back to the heat exchanger;
the heat exchanger, the mold passages, and the inlet and return conduits constituting a closed loop;
and heat exchanger control means for controlling operation of the heat exchanger to vaporize fluid from the liquid supply in the heat exchanger to maintain the conduits and the mold passages filled with fluid vapor at a controlled pressure;
the heat exchanger control means including means to adjust the pressure to establish a maximum limit temperature for heating of the mold and means for actuating the heat exchanger to vary the loop pressure in synchronism with the molding cycle.

3 more elements

Dependencies are inferred from the claim text.