Extrusion Head With Planarized Edge Surface

• US 20080099952A1
• Filed: 11/01/2006
• Published: 05/01/2008
• Est. Priority Date: 11/01/2006
• Status: Active Grant

• Current Assignee: Solarworld Innovations GmbH (Solarworld AG)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Fork, David K., Zimmermann, Thomas S.
• Granted Patent: US 7,780,812 B2
• Time in Patent Office: Days
• US Class Current: 264/173.16
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/345 Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising
• CPC Class Codes: B81C 99/0015 for microextrusion extrusion heads in general B29C48/30
• CPC Class Codes: Y10T 156/108 Flash, trim or excess removal

Abstract

A co-extrusion head for forming high-aspect ratio gridline structures in a micro extrusion apparatus includes multiple sheets (e.g., metal plates) that are machined and assembled to define three-part fluidic channels having associated outlet orifice disposed along an edge surface of the head. Reference surfaces are also etched in the sheets and are aligned in a straight line that intersects output junctions of the three-channel cavities. After assembly (e.g., using high pressure bonding techniques), each reference surface is located inside a notch defined in the edge surface. The edge surface of the co-extrusion head is then trimmed (e.g., machined by wire EDM) using the reference surfaces as a precise guide, thereby producing uniform length outlet orifices with uniform flow impedance.

Claims

1. A method for fabricating an extrusion head for a micro extrusion apparatus, the extrusion head having a plurality of fluidic channels for extruding material on a substrate, the method comprising:

forming a first sheet such that the first sheet defines at least one reference surface and an extrusion cavity including an outlet region such that the at least one reference surface in proximity to the outlet region;

securing the first sheet between second and third sheets to form said extrusion head such that the extrusion cavity and one or more of the second and third sheets form an associated fluidic channel, and such that the extrusion head includes an edge surface defining an outlet orifice communicating with said outlet region of the extrusion cavity, wherein the at least one reference surface is disposed on the edge surface such that the at least one reference surface is offset from the edge surface; and

trimming the edge surface by removing material from the extrusion head until the at least one reference surface is separated from the edge surface by a predetermined distance.

2. The method according to claim 1, wherein forming the extrusion cavity comprises defining a central cavity and opposing first and second side cavities arranged such that the central channel and first and second side cavities communicate with the associated outlet region.

3. The method according to claim 2, wherein the first and second side cavities define an effective width of the extrusion cavity, and wherein forming the at least one reference surface comprises disposing first and second reference surfaces within the effective width of the extrusion cavity.

4. The method according to claim 2, further comprising forming the second and third sheets such that each of the second and third sheets includes an inlet opening that, after said securing, is disposed opposite to a closed end of one of said central and first and second side cavities.

5. The method according to claim 2, wherein securing the first sheet between the second and third sheets comprises positioning the first sheet between the second and third sheets, and then utilizing at least one of an adhesive and high pressure to bond the second and third sheets to the first sheet.

6. The method according to claim 2, wherein trimming the edge surface comprises machining the edge surface and measuring the distance between the edge surface and the at least one reference surface.

7. The method according to claim 1,

wherein forming the first sheet comprises forming multiple rows, each of said multiple rows including a plurality of said reference surfaces and said extrusion cavities arranged in a straight line;

wherein securing the first sheet between second and third sheets to form said extrusion head comprises;

forming a block including said multiple rows of said reference surfaces and said extrusion cavities; and

dicing said block to separate said multiple rows along corresponding edge surfaces, thereby producing multiple extrusion heads, each of said multiple extrusion heads including a corresponding row of said reference surfaces and said extrusion cavities disposed along an associated one of said corresponding edge surfaces.

8. The method according to claim 7, wherein forming said first, second and third sheets comprises forming at least one dicing notch in each of the first, second and third sheets, and wherein dicing said block comprises cutting said stacked plates along a straight line extending between associated dicing notches.

9. The method according to claim 7, wherein forming said first sheet comprises forming a plurality of T-shaped openings such that each T-shaped opening has a vertical portion communicating with the outlet region of an associated extrusion cavity, a horizontal portion, and first and second bar portions disposed at opposing ends of the horizontal portion, wherein first and second said reference surfaces are disposed in the first and second bar portions, respectively.

10. The method according to claim 9, wherein dicing said block comprises cutting the block along the horizontal portion.

11. An extrusion head for a micro extrusion apparatus, the extrusion head comprising:

a first sheet having a first side edge;

a second sheet having a second side edge; and

a third sheet having a third side edge,

wherein the first sheet is mounted between the second and third sheets such that the first, second and third side edges are aligned to form an edge surface of the extrusion head,

wherein the first sheet defines a cavity that is enclosed by corresponding portions of the second and third sheets to form a fluidic channel having an outlet orifice defined in the first side edge of the first sheet such that the outlet orifice is coplanar with the edge surface of the extrusion head, and

wherein the first sheet also defines first and second reference surfaces that are disposed in indentations defined in the first side edge on opposite sides of the output orifice such that the first and second reference surfaces are offset from the edge surface by a predetermined distance.

12. The extrusion head according to claim 11, wherein the extrusion cavity comprises a central cavity and opposing first and second side cavities arranged such that the central channel and first and second side cavities communicate with the associated outlet orifice.

13. The extrusion head according to claim 12, wherein the first and second side cavities define an effective width of the extrusion cavity, and wherein the first and second reference surfaces are disposed within the effective width of the extrusion cavity.

14. The extrusion head according to claim 12, wherein each of the second and third sheets includes an inlet opening that is disposed opposite to a closed end of one of said central and first and second side cavities.

15. The extrusion head according to claim 11, wherein the edge surface is planar.