Method and apparatus for obtaining doses for forming an annular seal

Apparatus for obtaining doses intended to form an annular seal in a crown cap, wherein said apparatus comprises:

• extrusion means of a total flow of plastics comprising an exact N number of extrusion outlets to which said total flow of plastics is supplied to obtain a partial flow of extruded plastics exiting from each extrusion outlet and the same number of supply channels arranged to supply said total flow of plastics to said extrusion outlets each supply channel being placed in flowing communication with a respective extrusion outlet;
• flow adjustment means arranged to adjust each partial flow exiting from each extrusion outlet, said flow adjustment means comprising at least N-1 adjustment members, each adjustment member being operationally associated with a respective supply channel;
• dose separating means arranged to separate N doses of plastics that are precursors of said annular seal, said dose separating means comprising:
• a support element that is movable in an advancement direction along a closed loop path arranged so as to pass, at each revolution, in front of a respective extrusion outlet;
• and
• N dose separating elements fitted to said support element so as to take at least one annular arrangement to enable an ejection of said doses according to a corresponding annular arrangement, each of said N dose separating elements being arranged to separate, at each revolution of said support element, a respective dose of plastics from a respective extrusion outlet;
• wherein the N number is equal to three or four or five.