Capacitive detector for use in extrusion-based digital manufacturing systems

• US 8,222,908 B2
• Filed: 02/16/2010
• Issued: 07/17/2012
• Est. Priority Date: 02/16/2010
• Status: Active Grant

• Current Assignee: Stratasys Incorporated
• Original Assignee: Stratasys Incorporated
• Inventors: Paul, Thomas P., Batchelder, J. Samuel
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): Baldridge, Benjamin M
• Application Number:
  US12/706,095
• Publication Number:
  US 20110199104A1
• Time in Patent Office: 882 Days
• Field of Search: 324/679
• US Class Current: 324/679
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 40/00 Auxiliary operations or equipment, e.g. for material handling
• CPC Class Codes: G01N 27/22 by investigating capacitance

Abstract

A detector for use in an extrusion-based digital manufacturing system, the detector comprising a sense conductive component and an excitation conductive component to define a first gap that is configured to receive a consumable material used in the extrusion-based digital manufacturing system, where the excitation conductive component is configured to generate a first electrical field across the first gap.

Claims

1. A detector for use in an extrusion-based digital manufacturing system, the detector comprising:

a control board configured to be retained in the extrusion-based digital manufacturing system;

a sense conductive component operably secured to the control board;

an excitation conductive component operably secured to the control board to define a first gap between the sense conductive component and the excitation conductive component, the first gap being configured to receive a consumable material used in the extrusion-based digital manufacturing system, wherein the excitation conductive component is configured to generate a first electrical field across the first gap; and

a reference conductive component operably secured to the control board on an opposing side of the excitation conductive component from the sense conductive component to define a second gap between the excitation conductive component and the reference component, wherein the excitation conductive component is further configured to generate a second electrical field across the second gap.

2. The detector of claim 1, wherein the control board is configured to be operably mounted to a purge receptacle of the extrusion-based digital manufacturing system, and wherein the consumable material comprises an extrudate from an extrusion head of the extrusion-based digital manufacturing system.

3. The detector of claim 1, wherein the control board is configured to communicate with a controller of the extrusion-based digital manufacturing system.

4. The detector of claim 1, wherein the control board is operably mounted adjacent to a pathway of the consumable material between a supply source of the consumable material and an extrusion head of the extrusion-based digital manufacturing system.

5. The detector of claim 1, wherein the excitation conductive component is offset from the sense conductive component by an offset distance ranging from about 0.3 centimeters to about 2.5 centimeters.

6. The detector of claim 1, wherein the sense conductive component and the excitation conductive component each have a surface area ranging from about 0.2 square-centimeters to about 4.0 square-centimeters.

7. The detector of claim 1, wherein the consumable material used in the extrusion-based digital manufacturing system has a filament geometry and a composition that comprises a thermoplastic material.

8. A detector for use in an extrusion-based digital manufacturing system, the detector comprising:

a control board configured to be retained in the extrusion-based digital manufacturing system;

an excitation conductive component operably secured to the control board;

a sense conductive component operably secured to the control board;

a reference conductive component operably secured to the control board on an opposing side of the excitation conductive component from the sense conductive component to define a gap between the excitation conductive component and the reference component;

a biasing component configured to engage a consumable material with the excitation conductive component and the reference conductive component, wherein the excitation conductive component is configured to generate an electrical field with the sense conductive component; and

a processor operably secured to the control board and configured to compare capacitive values of sampled signals operably received from the sense conductive component to predetermined capacitive values to identify at least one compositional property of the consumable material.

9. The detector of claim 8, wherein the control board is configured to communicate with a controller of the extrusion-based digital manufacturing system.

10. The detector of claim 8, wherein the control board is operably mounted adjacent to a pathway of the consumable material between a supply source of the consumable material and an extrusion head of the extrusion-based digital manufacturing system.

11. The detector of claim 8, wherein the excitation conductive component is offset from the sense conductive component by an offset distance ranging from about 50 micrometers to about 250 micrometers.

12. The detector of claim 8, wherein the at least one compositional property comprises a moisture concentration in the consumable material.

13. A method for detecting a consumable material in an extrusion-based digital manufacturing system, the method comprising:

generating a first electrical field between an excitation conductive component and a sense conductive component;

generating a second electrical field between the excitation conductive component and a reference conductive component;

introducing the consumable material between the excitation conductive component and the sense conductive component of the extrusion based digital manufacturing system while the first and second electrical fields are generated;

sampling capacitive values of the first and second electrical fields while the consumable material is introduced between the excitation conductive component and the sense conductive component; and

performing at least one computational analysis on the sampled capacitive values to identify the presence of the consumable material between the excitation conductive component and the sense conductive component.

14. The method of claim 13, wherein the excitation conductive component, the sense conductive component, and the reference conductive component are operably mounted to a purge receptacle of the extrusion-based digital manufacturing system, and wherein the consumable material comprises an extrudate from an extrusion head of the extrusion-based digital manufacturing system.

15. The method of claim 13, wherein the excitation conductive component, the sense conductive component, and the reference conductive component are operably mounted adjacent to a pathway of the consumable material between a supply source of the consumable material and an extrusion head of the extrusion-based digital manufacturing system.

16. The method of claim 13, wherein performing the at least one computational analysis comprises determining differences between the sampled capacitive values.

17. The method of claim 13, and further comprising determining a baseline value based on differences between the sampled capacitive values, wherein the computational analysis is further based on the baseline value.

18. The method of claim 13, and further comprising communicating with a controller of the extrusion-based digital manufacturing system based at least in part on the at least one performed computational comparison.

19. The method of claim 18, wherein communicating with the controller comprises transmitting at least one signal to the controller relating to a loss of extrusion event.