Method and apparatus for determining extrudate flow in three-dimensional (3D) printing

Patent metadata

Field	Value
Publication number	US-11241836-B2
Application number	US-201815949499-A
Country	US
Kind code	B2
Filing date	Apr 10, 2018
Priority date	Apr 14, 2017
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

An additive manufacturing apparatus, and corresponding method, determine a mass (or volume) output flow rate of extrudate used in three-dimensional (3D) printing, and such determination is insensitive to rheological properties of a material of the extrudate being printed. A thermal energy balance on a liquefying extrusion head enables a load on a heater, used to heat the extrusion head, to be related to the output flow rate of extrudate. Based on the thermal energy balance, the output flow rate may be determined based on a duty cycle of the heater. The output flow rate may be employed to affect the 3D printing to prevent over- or under-extrusion of the extrudate and to identify a fault condition.

First claim

What is claimed is:

1. A computer-implemented method for additive manufacturing, the method comprising:
instructing a heating element of a 3D printing system to maintain a setpoint temperature of an extrusion head of the 3D printing system;
receiving information pertaining to a duty cycle of the heating element; and
based on the received information, determining an output flow rate of an extrudate output by the extrusion head according to a known duty cycle of the heating element for no extrudate output and a known rate of increase in extrude output as a function of the duty cycle of the heating element.

2. The method of claim 1 , wherein the determining step is also based on at least one of a density or a heat capacity of a build material fed into the extrusion head.

3. The method of claim 1 , wherein the determining step is also based on at least one of a temperature of the extrudate or a temperature of a build material before the build material is fed into the extrusion head.

4. The method of claim 1 , the method further comprising: based on the determined output rate, communicating an instruction to the 3D printing system to change an input flow rate of a build material into the extrusion head to a modified input flow rate.

5. The method of claim 4 , the method further comprising: prior to communicating the instruction to the 3D printing system, comparing the determined output rate to an original input flow rate of the build material into the extruder.

6. The method of claim 4 , the method further comprising: based on the comparison, determining if the extrudate is being either over- or under-extruded.

7. The method of claim 1 , wherein the determining step is also based on a loss of heat by the extruder to a surrounding environment.

Assignees

• Desktop Metal Inc

Inventors

• Barbati Alexander C
• Myerberg Jonah Samuel

Classifications

• B29C64/209 Primary

  Heads; Nozzles · CPC title

• B29C64/118

  using filamentary material being melted, e.g. fused deposition modelling [FDM] · CPC title

• B33Y30/00

  Apparatus for additive manufacturing; Details thereof or accessories therefor · CPC title

• B29C64/106

  using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material · CPC title

• B29C64/343

  Metering · CPC title