NOZZLE FOR EMITTING SOLID CARBON DIOXIDE PARTICLES WITH AN AXIALLY DISPLACEABLE VALVE MEMBER; APPARATUS FOR COOLING A HEATED WELD ZONE WITH SUCH A NOZZLE; WELDING APPARATUS WITH SUCH COOLING APPARATUS

摘要

The invention relates to a nozzle (16) for emitting solid carbon dioxide particles. The nozzle (16) comprising an inlet (30) for receiving liquid carbon dioxide, a nozzle aperture (32) from which solid carbon dioxide particles flow from the nozzle (16), a duct extending between the inlet (30) and the nozzle aperture (32), the duct having a convergent section (36) and a divergent section (38), and an axially displaceable valve member (42) located within the duct, the valve member (42) having first and second convergent portions and a substantially cylindrical portion located between the first and second convergent portions. The nozzle (16) finds particular use in apparatus for cooling a heated weld zone in a workpiece.