Nozzle for extruding a preform tube

An assembly for extruding a hollow tubular preform, the extrusion assembly comprising:

• a mandrel extending along a vertical axis;
• an annular nozzle body spacedly radially from and surrounding the mandrel;
• a holding ring having an upper end axially slidable in the nozzle body, braced axially downwardly against the nozzle body, and having a lower end spaced radially inward from and shiftable limitedly radially relative to the nozzle body;
• a nozzle ring having an upper end axially slidable in the holding ring, braced axially downwardly against the nozzle body, and having a radially deflectable lower end forming an annular extrusion gap with the mandrel;
• adjustment means for moving the nozzle ring and the mandrel parallel to the axis relative to each other by programmable adjustment motions to impart a varying wall thickness to the hollow tubular preform extruded through the gap;
• a first positioner engageable in a first radial direction with the lower end of nozzle ring and operable to radially deflect the lower end thereof in the first radial direction;
• and
• a second positioner engageable radially in a second radial direction angularly offset from the first radial direction with the nozzle ring for radially deflecting same in the second direction.