Patent ID: 7927531

Claim:
A method for depositing by extrusion a polymeric material by means of an extrusion head comprising a head body and at least one conveyor element coaxially mounted between each other about a common axis, said head body comprising at least one feeding duct disposed through a radially inner surface of said head body and a radially outer surface of said head body and extending in a direction substantially perpendicular to a longitudinal axis of an inner cavity of said head body, said feeding duct adapted for feeding said polymeric material in a lamination channel defined between said head body and said conveyor element, said method comprising a) feeding said polymeric material in said feeding duct; and b) conveying a part of said polymeric material towards at least one undercut arranged in proximity of an end of said feeding duct, said at least one undercut defining an elastically deformable sealing-element formed on one of the inner surface of said head body and the outer surface of said conveyor element, the sealing-element being lip-shaped and extending in a direction substantially parallel to said longitudinal axis, said part of said polymeric material exerting a sealing action between said head body and said at least one conveyor element by pushing on the sealing-element.