Extrusion die, esp. for mfg. hollow aluminium alloy profiles - where short mandrel is accurately centred in die bore, esp. for mfg. tubes

摘要

The die consists of two parts, viz. an outer die contg. one or more holes forming the periphery of the extrudate; and screwed into die is a bridge contg. one or more inlet chambers adjacent to the extruder barrel. The base of the inlet chamber is formed by the rear end of a mandrel and the sloping surfaces of webs which join the mandrel to the outer ring section of the bridge. The inlet chamber pref. increases in dia. away from the extruder barrel, and then tapers towards the rear end of the mandrel; and the bridge pref. forms three holes leading to a ring cavity surrounding the front end of the mandrel. This design of die prevents changes in the cross-section dimensions of the extrudate (e.g. a tube) during the extrusion process; and the die has long working life.