Cooling and pelletizing extruded thermoplastic strands

摘要

Apparatus is provided for controlled cooling of thermoplastic strands between the time that they are extruded from a melt of thermoplastic material until they are cut into pellets by a pelletizer that pulls the strands into it. A first tray inclined downwardly from the extruder receives the strands which are sprayed with cooling liquid while in the tray. A second tray inclined upwardly from the bottom of the first tray toward the pelletizer receives the strands which are also sprayed while in the second tray. Cooling liquid is also introduced at the inlet end of the first tray. A gravity liquid removal screen is positioned at the low point of each tray to remove the cooling liquid from the trays. A vacuum system for removing cooling liquid from the strands may also be positioned between the higher end of the second tray and the pelletizer. The temperature and quantity of the cooling liquid sprayed on the first tray, that sprayed on the second tray, and that introduced at the inlet end of the first tray are individually controlled by a cooling liquid control system utilizing a programmable central micro-processor.