Rotary joint for transferring melted plastic

Abstract

A rotary joint for transferring melted plastic from at least one extruder to a plurality of molds of a rotary machine for molding preforms, the joint comprising a fixed structure (') provided with a fixed longitudinal element () therein, defining a longitudinal axis (Y), and a movable structure (″) which can rotate about said axis (Y) and is adapted to be integrally fixed to the rotary machine; wherein a first passage channel () is provided within said fixed element (); wherein a second passage channel (′) is provided within said movable structure (″) and coaxial to said first passage channel; said second passage channel (′) being in communication at a first end thereof with said first passage channel (), and being in communication at a second end thereof with a plurality of lateral radial channels () provided within said movable structure (″); wherein there is provided, between the fixed structure (′) and the movable structure (″), a gap in which a spiral seal () is arranged for ensuring the action of sealing the melted plastic between said fixed structure and said movable structure.