Apparatus for the thermal densification of thermoplastic articles

An apparatus for the batch thermal densification of thermoplastic articles, comprising:

• a) a thermally insulated closeable cabinet including a top access with a lid for loading thermoplastic articles and a lower access for the removal of densified thermoplastic material;
• b) a hopper mounted within the cabinet, the hopper comprised of:
• i) an upper section;
• ii) a lower pan chamber having a top and a bottom, the lower pan chamber being in communication with the upper section and the access, wherein the lower pan chamber contains a separate front access;
• and
• iii) an air distribution plenum located at the top of the lower pan chamber;
• c) a convection heating system comprising:
• i) an air heat exchange chamber having an upper section and a lower section and positioned between the cabinet and the hopper wherein the air heat exchange chamber is adapted to create a circulating air flow around the hopper;
• ii) an upper heater chamber adjacent to the hopper and in communication with the air heat exchange chamber, the upper heater chamber being adapted to create a circulating air flow around the hopper and into the air distribution plenum;
• iii) a heater in the heater chamber adapted to heat the circulating air flow to a temperature effective for the thermal densification of thermoplastic articles in the hopper;
• and
• iv) an air temperature control responsive to a temperature sensor located in the upper heater chamber, wherein the air temperature control and the means for heating cooperate to maintain the upper heater chamber circulating air flow at a temperature effective for the thermal densification of thermoplastic articles;
• g) a removable pan located in the lower pan chamber for collecting densified thermoplastic material;
• and
• h) a pan heater system adapted to maintain the pan at a temperature suitable for the even filling of the pan with densified thermoplastic material responsive to a pan temperature sensor.