A mixing and extrusion machine (10) for the manufacture of rubber mixtures has a mixer with a converging conical twin screw (12) with a fixed frame (14) that supports sleeves (16). Two screws (18), being mounted at an angle, are mounted in the mixer (12) so as to move in translational movement between an opening (22) arranged upstream and an outlet (25) arranged downstream of the sleeves, so that the thread tips of each screw contact tangentially the surfaces of the opposite screw so that the screws remain substantially in contact with each other when the screws rotate at an angle and at a center distance that facilitates self-cleaning. The screw threads maintain tangential contact with the inner surfaces of the sleeves, thus preventing the retention of mixing material on these surfaces.

A mixing and extrusion machine (10) for the manufacture of rubber mixtures has a mixer with a converging conical twin screw (12) with a fixed frame (14) that supports sleeves (16). Two screws (18), being mounted at an angle, are mounted in the mixer (12) so as to move in translational movement between an opening (22) arranged upstream and an outlet (25) arranged downstream of the sleeves, so that the thread tips of each screw contact tangentially the surfaces of the opposite screw so that the screws remain substantially in contact with each other when the screws rotate at an angle and at a center distance that facilitates self-cleaning. The screw threads maintain tangential contact with the inner surfaces of the sleeves, thus preventing the retention of mixing material on these surfaces.