Liquefier assembly with multiple-zone plate heater assembly

• US 10,131,131 B2
• Filed: 10/04/2013
• Issued: 11/20/2018
• Est. Priority Date: 10/04/2013
• Status: Active Grant

• Current Assignee: Stratasys Incorporated
• Original Assignee: Stratasys Incorporated
• Inventors: Batchelder, J. Samuel, Swanson, William J., Johnson, Kevin C.
• Primary Examiner(s): Ochylski, Ryan M
• Application Number:
  US14/046,301
• Publication Number:
  US 20150097053A1
• Time in Patent Office: 1,873 Days
• CPC Class Codes: B29C 64/209 Heads; Nozzles
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor

Abstract

A liquefier assembly for use in an additive manufacturing system, which includes a rigid member having a gap, a liquefier tube operably disposed in the gap, one or more heater assemblies disposed in the gap in contact with the liquefier tube, and configured to heat the liquefier tube in a zone-by-zone manner, preferably one or more thermal resistors disposed in the gap between the rigid member and the heater assemblies, and preferably one or more sensors configured to operably measure pressure within the liquefier tube. The one or more heater assemblies may be operated to provide dynamic heat flow control.

Claims

1. A liquefier assembly for use in an additive manufacturing system, the liquefier assembly comprising:

a liquefier tube having a main body with an inlet end and an outlet end offset along the longitudinal axis, the main body comprising;

a first set of spaced apart substantially flat side walls spaced substantially a first distance apart from each other; and

a second set of spaced apart side walls connecting the first set of spaced apart side walls such that the first set of side walls and the second set of side walls form a perimeter of the main body, wherein the second set of spaced apart are spaced apart at most a second distance wherein an aspect ratio of the first distance to the second distance ranges from about 3;

1 to about 10;

1;

a plate heater assembly comprising;

a plate portion positioned having a proximal region in direct contact with one of the substantially planar walls of the first set of walls;

a plurality of conductor traces disposed on the plate portion, and configured to operably receive electrical power from the additive manufacturing system with independently controlled wattage levels; and

a plurality of heating elements disposed on the plate portion, and each heating element in contact with one or more of the conductor traces to receive the electrical power from the one or more conductor traces and transfer heat to the proximal region of the plate portion, wherein an electrical resistance is measured across each heating element, and the electrical resistance is correlated to a temperature, wherein the electrical resistance provides feedback to independently control wattage levels to each heating element and cause the heating elements to independently heat different zones of the liquefier tube to different temperatures along the longitudinal axis.

2. The liquefier assembly of claim 1, wherein the plurality of conductor traces include three to eleven conductor traces.

3. The liquefier assembly of claim 1, and further comprising a thermal resistor disposed against the plate heater assembly, opposite of the liquefier tube.

4. The liquefier assembly of claim 1, wherein plate portion comprises a distal region that is spaced from the liquefier tube, and which is configured to engage with an electrical connector of a print head that retains the liquefier assembly.

5. The liquefier assembly of claim 1, wherein the first set of side walls and the second set of side walls define a substantially rectangular cross-section.

6. A liquefier assembly for use in an additive manufacturing system, the liquefier assembly comprising:

a liquefier tube having a main body with an inlet end and an outlet end offset along the longitudinal axis, the main body comprising;

a first set of spaced apart substantially flat side walls spaced substantially a first distance apart from each other; and

a second set of spaced apart side walls connecting the first set of spaced apart side walls such that the first set of side walls and the second set of side walls form a perimeter of the main body, wherein the second set of spaced apart are spaced apart at most a second distance wherein an aspect ratio of the first distance to the second distance ranges from about 3;

1 to about 10;

1;

a first heater assembly comprising;

a plurality of first conductor traces; and

a plurality of first heating elements in contact with the first conductor traces to receive electrical power from the first conductor traces;

a first plate having a first portion in contact with both the plurality of first heating elements and a first side wall of the first set of spaced apart side walls; and

a second heater assembly comprising;

a plurality of second conductor traces; and

a plurality of second heating elements in contact with the second conductor traces to receive electrical power from the second conductor traces;

a second plate having a first portion in contact with both the plurality of second heating elements and a second side wall of the first set of spaced apart side walls wherein the first portions of the first and second heating elements are spaced from each other;

wherein each of the first and second heating elements heat the liquefier tube to different temperatures in a zone-by-zone manner by measuring an electric resistance across each heating element and adjusting a wattage delivered to each heating element based upon the measured electric resistance.

7. The liquefier assembly of claim 6, wherein the first and second conductor traces include the same number of conductor traces ranging from three to eleven conductor traces.

8. The liquefier assembly of claim 6, wherein the first set of side walls and the second set of side walls define a substantially rectangular cross-section.

9. The liquefier assembly of claim 6, wherein the liquefier tube has a length between the inlet end and the outlet end ranging from about 0.3 inch to about 5 inches.

10. The liquefier assembly of claim 6, and further comprising:

a first thermal resistor disposed against the first heater assembly, opposite of the liquefier tube; and

a second thermal resistor disposed against the second heater assembly, opposite of the liquefier tube.

11. A print head for use in an additive manufacturing system, the print head comprising:

a drive mechanism configured to feed a consumable material at multiple feed rates;

a liquefier tube configured to receive the fed consumable material, the liquefier tube comprising;

a first set of spaced apart substantially flat side walls spaced substantially a first distance apart from each other; and

a second set of spaced apart side walls connecting the first set of spaced apart side walls such that the first set of side walls and the second set of side walls form a perimeter of the main body, wherein the second set of spaced apart are spaced apart at most a second distance wherein an aspect ratio of the first distance to the second distance ranges from about 3;

1 to about 10;

1; and

at least one plate heater assembly having a portion positioned in contact with one of the first set of spaced apart substantially flat side walls, the at least one heater assembly comprising a plurality of conductor traces and a plurality of heating elements in contact with the conductor traces, wherein the conductor traces are configured to relay electrical power to the heating elements to generate multiple heating zones along the liquefier tube wherein a electric resistance is measured across each of the plurality of heating elements wherein the measured electric resistance provides feed back to independently and dynamically adjusts a temperature profile along the liquefier tube with changes in the feed rates of the consumable material.

12. The print head of claim 11, and further comprising a housing, wherein the drive mechanism is disposed at least partially within the housing.

13. The print head of claim 11, wherein the liquefier tube has a length between the inlet end and the outlet end ranging from about 0.3 inch to about 5 inches.

14. The print head of claim 11, wherein the at least one plate heater assembly comprises two plate heater assemblies disposed on opposing sides of the liquefier tube wherein each plate heater independently and dynamically adjusts the temperature profile along the liquefier tube by measuring an electric resistance across each heating element and using the measured electric resistance as feed back to adjust a wattage to each heating element.

15. The print head of claim 11, wherein the first set of side walls and the second set of side walls define a substantially rectangular cross-section.