Device And Method For Feeding Polymeric Material To A Printhead Of An Additive Manufacturing Machine And Additive Manufacturing Machine

Abstract

A feeding device for feeding a polymeric material to a print head of an additive manufacturing machine has a feed cylinder that flows directly into the print head at a fitting to feed the polymeric material into the print head; and a movable pusher within the feed cylinder to advance the polymeric material towards the print head.

Claims

1. A feeding device for feeding a polymeric material to a print head of an additive manufacturing machine; the feeding device comprising: a feed cylinder that flows directly into the print head at a fitting to feed the polymeric material into the print head; and a movable pusher within the feed cylinder for advancing and pushing the polymeric material towards the print head.

2. The feeding device as claimed in claim 1, wherein the pusher is a selectively movable piston of alternating motion within the feeding cylinder.

3. The feeding device as claimed in claim 1, wherein said feeding cylinder comprises a ventilation opening arranged proximate to said fitting.

4. The feeding device as claimed in claim 3, and comprising a filter arranged at said ventilation opening.

5. The feeding device as claimed in claim 1, and comprising an actuator for alternately driving the pusher.

6. The feeding device as claimed in claim 1, wherein the feed cylinder comprises a feed opening for allowing polymeric material to be fed into the feed cylinder.

7. The feeding device as claimed in claim 6, and comprising a further attachment arranged at the feeding opening to allow feeding polymeric material to the feeding cylinder.

8. feeding device as claimed in claim 1, and comprising a storage container configured to contain and dispense polymeric material; a pneumatic device; and a tube, in particular a hose, for pneumatically transferring the polymeric material from the storage container to said feeding cylinder.

9. An additive manufacturing machine, the machine comprising a print head for molding polymeric material comprising a cylindrical body, a nozzle at one end of the cylindrical body, and an extrusion screw selectively rotatable within the cylindrical body for melting and advancing the polymeric material in a given direction towards the nozzle; at least one feeding device as claimed in claim 1 and wherein the feeding cylinder is connected to the cylindrical body.

10. The machine as claimed in claim 9, and comprising two feeding devices arranged symmetrically from opposite sides with respect to the cylindrical body and wherein two feeding cylinders are connected to the cylindrical body.

11. The machine as claimed in claim 9, and comprising a robot, in particular a robot with at least four axes, said print head being mounted at the distal end of the robot.

12. A method of feeding polymeric material to a print head of an additive manufacturing machine, the method comprising pushing the polymeric material along a feed cylinder flowing directly into the print head at a fitting to feed the polymeric material into a cylindrical body of the print head via a pusher movable within the feed cylinder to advance the polymeric material towards the print head.

13. The method as claimed in claim 12 and comprising actuating the pusher of alternating motion via an actuator between a vent opening in proximity of said print head and a feed port.

14. The method as claimed in claim 12, and comprising pneumatically transferring polymeric material from a storage container to the feed cylinder via a tube and a pneumatic device.

Description

DESCRIPTION OF THE DRAWINGS

[0038] Further characteristics and advantages of the present invention will become clear from the following description of non-limiting embodiments thereof, with reference to the Figures of the attached drawings, in which:

[0039] FIG. 1 is a perspective view, with parts removed for clarity's sake and parts shown schematically, of an additive manufacturing machine in accordance with the present invention;

[0040] FIG. 2 is a schematic elevation view, with parts removed for clarity's sake and to an enlarged scale, of a detail of the machine of FIG. 1;

[0041] FIG. 3 is a schematic elevation view, with parts removed for clarity's sake, sections and in a reduced scale, of the machine of FIG. 1; and

[0042] FIG. 4 is an elevation schematic view, with parts removed for clarity's sake, parts in section and in reduced scale, of an alternative embodiment of the machine of FIG. 1.

PREFERRED EMBODIMENT OF THE INVENTION

[0043] In FIG. 1, an additive manufacturing machine is denoted by reference number 1. The machine 1 comprises a robot 2, specifically an anthropomorphic robot with six axes denoted A1, A2, A3, A4, A5, and A6; a print head 3 coupled to the distal end of the robot 2 to produce a manufactured product P using the additive manufacturing technique; and a feeding device 4 to feed a polymeric material to the print head 3.

[0044] The print head 3 comprises a connecting element 5; a bearing 6 supported by the connecting element 5; and an extruder 7, which is mounted inside the bearing 6 and extends along a longitudinal axis A coaxial to the bearing 6. In the specific case illustrated, the connecting element 5 comprises a flange connecting to the robot 2, a ring connecting to the bearing 6, and an arm extending between the flange and the ring.

[0045] The print head 3 comprises an actuator 8 and a drive element 9 to rotate the extruder 7 about its longitudinal axis A.

[0046] Referring to FIG. 2, the extruder 7 comprises a cylindrical body 10 extending along the longitudinal axis A and defining a melting chamber; a nozzle 11 arranged at the free end of the cylindrical body 10; an extrusion screw 12 rotatable within the cylindrical body 10 about the longitudinal axis A.

[0047] The extruder 7 also comprises heating elements associated with the cylindrical body 10 which are not shown in the attached figures and which, in this case, are electrical resistors and an actuator 13 to rotate the extrusion screw 12.

[0048] The feeding device 4 for feeding a polymeric material to the print head 3 comprises a feed cylinder 14 that flows directly into the print head 3 at a fitting; a pusher 15 movable inside the feed cylinder to advance the polymeric material towards the print head 3, in this case, into the cylindrical body 10.

[0049] The feeding device 4 further comprises a storage container 16 to contain the polymeric material; a tube 17 in this case a hose, which extends from the storage container 16 to the feed cylinder 14; and a pneumatic device 18 to transfer the polymeric material from the storage container 16 to the feed cylinder 14 along the tube 17.

[0050] The pusher 15 is a selectively movable piston of alternating motion within the feed cylinder 14. The tolerances between pusher 15 and feed cylinder 14 are very tight so that no material can pass between pusher 15 and feed cylinder 14. The feeding device 4 also comprises an actuator 19 to actuate the pusher 15 between an extended position in proximity of the print head 3 and a retracted position.

[0051] The feed cylinder 14 is attached to the print head 3 and has a ventilation opening 20 in proximity of the print head 3 and a feed opening 21 between the ventilation opening 20 and the retracted position of the pusher 15.

[0052] The feed cylinder 14 also has a filter 22 arranged above the ventilation opening 20 and a fitting 23 at the feed opening 21 to connect the tube 17 to the feed cylinder 14.

[0053] The pneumatic device 18 comprises a Venturi tube 24, which is connected to the tube 17, the storage container 16 and a nozzle 25 connected to the compressed air network to feed compressed air to the Venturi tube 24 and to drag along the tube 17 the polymeric material released from the storage container 16 into the Venturi tube 24.

[0054] The feeding device 4 comprises a control unit 26, which controls the actuation of the actuator 19 of the pusher 15 and nozzle 25 intended to feed compressed air so as to inhibit the pneumatic transport of the polymeric material when the pusher 15 is not in the retracted position.

[0055] In use, when the pusher 15 is in the retracted position, the polymer material is fed to the feed cylinder 14 via the tube 17 and the pneumatic device 18 and excess air is ejected through the ventilation opening 20 and dust particles are retained by the filter 22 so as not to pollute the print area. The filter 22 also has the function of preventing particles in the print area from entering the feed cylinder 14.

[0056] Subsequently, the pusher 15 applies a constant thrust to the material contained in the feed cylinder 14 while the air contained in the feed cylinder 14 is continuously ejected through the ventilation opening 21 until the pusher 15 is in the position of maximum extension in proximity of the ventilation opening 21. At this point, the pusher 15 is retracted and the feed cylinder 14 is once again filled with pneumatically transported polymeric material.

[0057] In the embodiment of FIG. 3, the additive manufacturing machine 1 comprises two feeding devices 4 for feeding a polymeric material to the print head and a single control unit 26 which manages the two feeding devices 4 in such a way as to ensure that at least one of the two pushers is always compressing and feeding the polymeric material along the respective feed cylinder 14.

[0058] Finally, it is clear that the present invention comprises further variants of the described embodiments included in the scope of protection of the appended claims.