Method for three-dimensional printing of an article in polymeric thermoplastic material

1 . A method for three-dimensional printing of an article in polymeric thermoplastic material, the method comprising:

providing an extrusion head equipped with a nozzle having a dispensing opening;

feeding said extrusion head with a thermoplastic polymeric material;

melting the thermoplastic polymeric material in the extrusion head;

moving the extrusion head according to at least three axes based on a predefined three-dimensional model;

during the movement of the extrusion head, dispensing molten thermoplastic polymeric material through the dispensing opening of the nozzle by depositing the molten thermoplastic polymeric material on a printing surface according to superimposed layers to form the printed article; and

wherein during the movement of the extrusion head and dispensing of the molten thermoplastic polymeric material, a concentrated heat source is moved along a printing direction conforming to the predefined three-dimensional model and an area of an upper surface of an underlying layer of solidified thermoplastic polymeric material is locally heated prior to the deposition of an overlying layer of molten thermoplastic polymeric material,

wherein the area locally heated by the concentrated heat source is from about one to about four times an area of the dispensing opening of the nozzle of the extrusion head.

2 . The method of claim 1 , wherein the concentrated heat source is a laser source, a hot air source, or a light source, the intensity of which is selectively controllable.

3 . The method of claim 1 , wherein the concentrated heat source is movable in accordance with the predefined three-dimensional model integrally with the extrusion head.

4 . The method of claim 1 , wherein the extrusion head and the concentrated heat source are rotatable on themselves according to an angle of 360°.

5 . The method of claim 1 , wherein the concentrated heat source is pivotally connected to the extrusion head, thereby rotating about at least one axis with respect to the extrusion head.

6 . The method of claim 1 , wherein the concentrated heat source is movable along a printing direction conforming to the predefined three-dimensional model through dedicated moving means, which are independent from the extrusion head.

7 . The method of claim 1 , further comprising:

joining a continuous reinforcing element to the melted thermoplastic polymeric material in the extrusion head to form a continuous flow of composite material comprising the continuous reinforcing element and the melted thermoplastic polymeric material; and

keeping the position of the continuous reinforcing element fixed with respect to the molten polymeric material inside the extrusion head.

8 . The method of claim 1 , wherein the concentrated heat source is mounted on dedicated moving means, and moving of the concentrated heat source is independent from moving the extrusion head.

9 . The method of claim 5 , wherein the concentrated heat source comprises a member extending obliquely to the at least one axis, and wherein during the movement of the extrusion head and dispensing of the molten thermoplastic polymeric material, the concentrated heat source is moved such that the obliquely extending member is oriented towards the dispensing opening.

10 . The method of claim 1 , wherein the extrusion head and the concentrated heat source are mounted to a common robotic arm configured to move the extrusion head and the single robotic arm together in three dimensions.

11 . The method of claim 6 , wherein the dedicated moving means is a dedicated robotic arm configured to move the concentrated heat source in three dimensions independently of the extrusion head.