COOLING OF WORKPIECE BELOW 0 DEGREES C, FOR USE IN FREEZE¹BRANDING

摘要

Workpieces such as branding irons 14 are cooled to a sub-zero temperature in a bath 10 of organic liquid. The bath 10 is provided with nitrogen injection means 24 comprising a header 26 having arms 28 each provided with nitrogen injection orifices 30. The header 26 communicates with a conduit 34 along which liquid nitrogen is passed and a vaporiser coil 39 for vaporising liquid nitrogen. Thus a cold nitrogen stream is formed by mixing the liquid nitrogen with the vaporised nitrogen. This cold nitrogen is injected into the bath 10 through orifices 30 and the organic liquid is sufficiently agitated to prevent local freezing of the organic liquid to the workpieces. IMAGE