The invention relates to an extrusion facility (10) that includes an extrusion screw (12), capable of providing a heat-softened viscous plastic material, and an extrusion head (14). Said extrusion head includes an annular chamber (24) that is capable of receiving said viscous plastic material. Said viscous plastic material, provided by said extrusion screw, has, at a constant temperature, a viscosity capable of varying from a value [mu]i at a constant value [mu]cst during a given period so that [mu]cst > [mu]i,said facility also includes a buffer chamber (16) set up between said extrusion screw (12) and said extrusion head (14) in order to store said viscous plastic material during said given period and in order to enable the plastic material to reach said viscosity value [mu]cst before being injected into said extrusion head (14).