Hydraulic method for fused deposition modeling

Abstract

A feed mechanism for feeding a filament into a print head assembly in an FDM printer. The feed mechanism includes a drive assembly that drives the filament into a reservoir where the reservoir is heated by a heater, where the filament is liquefied therein. A pump in the reservoir pumps the liquefied filament material out of the reservoir through an extrusion nozzle to a print head of the printer.

Claims

1. A feed mechanism for feeding a printing material through a print head assembly in a fusion deposition modeling (FDM) printer, said feed mechanism comprising: a heater for heating and liquefying the printing material; a reservoir for holding the liquefied printing material; a pump positioned within the reservoir and pumping the liquefied printing material out of the reservoir under pressure, wherein the pump is a rotary pump including a plurality of blades; and an extrusion nozzle receiving the liquefied printing material from the reservoir to be printed by the print head assembly.

2. The feed mechanism according to claim 1 wherein the printing material is provided as a filament to the heater.

3. The feed mechanism according to claim 2 further comprising a drive assembly including opposing circular drive elements for driving the filament to the heater.

4. The feed mechanism according to claim 3 further comprising a thermal isolation device provided between the heater and the drive assembly.

5. The feed mechanism according to claim 1 wherein the heater is positioned in contact with the reservoir and the printing material is liquefied in the reservoir.

6. The feed mechanism according to claim 1 wherein the heater is a resistive heater.

7. A feed mechanism for feeding a printing material through a print head assembly in a fusion deposition modeling (FDM) printer, said feed mechanism comprising: a drive assembly including opposing circular drive elements for driving a filament of the printing material; a reservoir receiving the filament from the drive assembly; a heater positioned in contact with the reservoir and heating the reservoir to liquefy the filament; a pump positioned within the reservoir and pumping the liquefied printing material out of the reservoir under pressure, wherein the pump is a rotary pump including a plurality of blades; and an extrusion nozzle receiving the liquefied printing material from the reservoir to be printed by the print head assembly.

8. The feed mechanism according to claim 7 further comprising a thermal isolation device provided between the reservoir and the drive assembly.

9. The feed mechanism according to claim 7 wherein the heater is a resistive heater.

10. A fusion deposition modeling (FDM) printer, said printer comprising a print head assembly including a feed mechanism for feeding a printing material through the print head assembly, said feed mechanism including a heater for heating and liquefying the printing material, a reservoir for holding the liquefied printing material, a pump positioned within the reservoir and pumping the liquefied printing material out of the reservoir under pressure, and an extrusion nozzle receiving the liquefied printing material from the reservoir to be printed by the print head assembly, wherein the pump is a rotary pump including a plurality of blades.

11. The FDM printer according to claim 10 wherein the printing material is provided as a filament to the heater.

12. The FDM printer according to claim 11 further comprising a drive assembly including opposing circular drive elements for driving the filament to the heater.

13. The FDM printer according to claim 12 further comprising a thermal isolation device provided between the heater and the drive assembly.

14. The FDM printer according to claim 10 wherein the heater is positioned in contact with the reservoir and the printing material is liquefied in the reservoir.

15. The FDM printer according to claim 10 wherein the heater is a resistive heater.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is front view of an FDM printer;

(2) FIG. 2 is a front view of a print head removed from the printer shown in FIG. 1;

(3) FIG. 3 is an illustration of a known feed mechanism employed in the print head shown in FIG. 2; and

(4) FIG. 4 is an illustration of feed mechanism including a heater that liquefies a filament that can replace the feed mechanism shown in FIG. 3 in the print head.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) The following discussion of the embodiments of the invention directed to a feed mechanism for an FDM printer is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses.

(6) FIG. 1 is a front view of a known FDM printer 10 of the type generally discussed above. It is noted that the specific configuration of the printer 10 is provided for general discussion purposes only in that the feed mechanism of the invention discussed in detail below can be employed in other FDM printers having different designs and configurations. The printer 10 includes an outer support structure 12 having top and bottom support members 14 and 16 and side support members 18 and 20 defining an enclosure 22. A movable platform 26 on which the component (not shown) being printed will be deposited in a layered configuration is positioned on the bottom member 16 within the enclosure 22. A pair of parallel rails 30 and 32 is mounted to the side members 18 and 20 and extends across the enclosure 22 in any suitable manner.

(7) A print head 36 is slidably mounted to the rails 30 and 32 so as to be controllably positioned along the rails 30 and 32 relative to the platform 26. FIG. 2 is a front view of the print head 36 separated from the printer 10, where some of the parts of the print head 36 have been removed for clarity purposes. A filament 40 is drawn into a print head assembly 42 in the print head 36 from, for example, a spool (not shown) of the filament material by a feed mechanism 44 positioned in the print head assembly 42. The feed mechanism 44 includes a drive gear 50 and a roller bearing 52 that draws the filament 40 through a feed channel 54, then through a heat sink 56 and into a nozzle 58 that is heated by a heat source 60. The heated filament material is then extruded by the nozzle 58 so that it is laid down on the platform 26 in a configuration that is controlled by the position of the print head 36 on the rails 20 and 22 and the orientation of the platform 26 in a manner well understood by those skilled in the art.

(8) FIG. 3 is an illustration of a feed mechanism 70 that is similar to the feed mechanism 44 to better illustrate the operation of the feed mechanism 44. The feed mechanism 70 includes a drive gear 72 having gear teeth 74 and a roller bearing 76 defining a space 78 therebetween. A filament 80 is drawn through the feed mechanism 70 by the gear 72 by applying pressure to a side of the filament 80 against the bearing 76. Because the pressure applied by the gear 72 causes a point source load against the filament 80 at location 82, and which creates a force off-set from the center of the filament 80, as represented by arrow 84, the issues with filament buckling and the like discussed above are created.

(9) The present invention proposes replacing the feed mechanism 44 in the print head assembly 42 with a different type of feed mechanism that prevents filament buckling and offers increased feed reliability. As will be discussed, instead of heating the filament 40 to make it pliable to be extruded out of an extrusion nozzle, the proposed feed mechanism actually liquefies the filament 40, which is delivered to the print head 36 in the liquefied state.

(10) FIG. 4 is an illustration of a feed mechanism 90 that receives a filament 92 of the type discussed above that is the printing material for the print head 36. The feed mechanism 90 includes a drive assembly 104 having a first circular drive element 94 rotatable on an axle 98 and a second circular drive element 100 rotatable on an axle 102, where a space is defined therebetween. Any suitable configuration of drive elements in the assembly 104 can be employed for the purpose discussed herein, such as that shown in FIG. 3. The filament 92 is inserted in the space between the drive elements 94 and 100 and in contact therewith, where rotation of the drive elements 94 and 100 on the axels 98 and 102, respectively, by a suitable motor (not shown) draws the filament 92 into a reservoir 106. The feed mechanism 90 includes a heating element 110, such as a resistive heater, positioned in contact with the reservoir 106 that heats the reservoir 106 to a temperature that liquefies the filament 92 therein. Any heating element suitable for the purposes discussed herein can be employed. The heating element 110 can be temperature controlled for different filament materials. A thermal isolation element 112 thermally isolates the reservoir 106 from the drive assembly 104 so that the filament 92 does not become too pliable to be driven. A pump 114, here a rotary pump including three blades 116, is positioned within the reservoir 106 and is rotated at the desired speed so that the liquefied filament material in the reservoir 106 is forced out of an extrusion nozzle 118 to the print head 36 for the printing process.

(11) The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.