| 摘要 |
A method and apparatus for internal cooling of extruded tube-shaped objects wherein liquid nitrogen is inserted into the tube and evaporated there out of contact with the tube on account of the heat from the tube whereafter only evaporated nitrogen is made to pass through the inner surfaces of the extruded tube. The apparatus for evaporation of the liquid nitrogen and for conduction of the gasified nitrogen comprises a cylinder-shaped member with good thermal conductivity placed in the shaped tube adjacent to the extruder nozzle. Provided in the closed end of the cylindrical member are nozzle members with a connection to a supply line for liquid nitrogen inserted through the extruder nozzle. Provided in the opposite end of the cylindrical member are openings for passage of the evaporated nitrogen out towards the shaped tube. The temperature in the evaporating arrangement near the said openings is regulated in such a manner that the temperature is always higher than the evaporation temperature of the nitrogen at the pressure prevailing in the tube, whereby all supplied nitrogen is evaporated before contacting inner surfaces of the extruded tube. |
