# US 7,607,225 B2 · Manufacture of flow optimized stiffener for improving rigidity of ducting

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- Number: US 7,607,225 B2
- Document ID: US7607225B2
- Status: Granted
- Kind: B2
- Application number: 11/162,261
- Filed: 2005-09-02
- Published: 2007-03-08
- Granted: 2009-10-27
- Earliest claimed: 2005-04-22
- Assignees: The Boeing Company
- Inventors: Christopher S. Huskamp; Victor Blakemore Slaughter
- Web page: https://patentgrep.com/patent/US7607225B2

## CPC

- B21C 37/06: of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
- B21C 23/145: {Interlocking profiles}
- B21C 37/104: {the tubes having a special shape, e.g. polygonal tubes}
- B22F 10/28: Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
- B22F 2998/00: Supplementary information concerning processes or compositions relating to powder metallurgy
- B33Y 80/00: Products made by additive manufacturing
- Y02P 10/25: Process efficiency
- Y10T 29/49398: Muffler, manifold or exhaust pipe making
- Y10T 29/49879: Spaced wall tube or receptacle
- B21C: MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method for the direct manufacture of aerospace duct elements is provided comprising executing a single build run on a build chamber using direct fabrication technology to generate at least one duct section. The at least one duct section is generated by forming a plurality of partial cylinder duct segments orientated within the build chamber in a nested arrangement during the single build run, and assembling at least two of the partial cylinder duct segments to form the duct section. During the single build run a plurality of stiffening protrusions are formed on each of the partial cylinder duct segments to improve duct rigidity and to modify flow through the duct section.

## Claims

### Claim 1

A method for the direct manufacture of aerospace duct elements comprising: executing a single build run on a build chamber using direct fabrication technology to generate at least one duct section, said at least one duct section generated by: forming a plurality of partial cylinder duct segments orientated within said build chamber in a nested arrangement during said single build run; forming a plurality of stiffening protrusions on each of said partial cylinder duct segments during said single build run; and assembling at least two of said partial cylinder duct segments to form said duct section, said duct section having a duct cross-sectional profile larger than a build chamber profile.

### Claim 2 (depends on 1)

A method as described in claim 1, wherein each of said plurality of partial cylinder duct segments includes a first segment end and a second segment end, said first segment end and said second segment end including mechanical lock features adapted to secure said at least two of said partial cylinder duct segments together to form said duct section.

### Claim 3 (depends on 1)

A method as described in claim 1, wherein said plurality of stiffening protrusions comprises: a plurality of spiral ridges formed on an inner surface of said partial cylinder duct segments.

### Claim 4 (depends on 3)

A method as described in claim 3, wherein said plurality of spiral ridges are configured to generate a rifled flow through said duct section.

### Claim 5 (depends on 1)

A method as described in claim 1, wherein said plurality of stiffening protrusions comprises: a plurality of ribbed ridges formed on an inner surface of said partial cylinder duct segments.

### Claim 6 (depends on 5)

A method as described in claim 5, wherein said plurality of ribbed ridges: generate a localized turbulent buffer zone immediately adjacent said inner surface; and generate a central laminar flow zone through said duct section.

### Claim 7 (depends on 1)

A method as described in claim 1, wherein said plurality of stiffening protrusions are positioned on an inner surface of said partial cylinder duct segments, said plurality of stiffening protrusions configured to modify flow through said duct segment.

### Claim 8 (depends on 1)

A method as described in claim 1, wherein said partial cylinder duct segments comprise half cylinder duct segments.

### Claim 9 (depends on 1)

A method as described in claim 1, wherein said direct metal fabricating comprises selective laser sintering.

### Claim 10 (depends on 1)

A method as described in claim 1, further comprising: generating a plurality of duct segments; and joining said plurality of duct segments to form an elongated duct run.

### Claim 11

A method for the direct manufacture of aerospace cylindrical elements comprising: executing a single build run on a build chamber using direct fabrication technology to generate at least one cylindrical section, said at least one cylindrical section generated by: forming at least two partial cylinder segments within said build chamber during said single build run; forming a plurality of stiffening protrusions on each of said partial cylinder segments during said single build run and assembling said partial cylinder segments to form said cylindrical section, said cylindrical section having a cylindrical cross-sectional profile larger than a build chamber profile.

### Claim 12 (depends on 11)

A method as described in claim 11, wherein each of said partial cylinder segments includes a first segment end and a second segment end, said first segment end and said second segment end including mechanical lock features adapted to secure said partial cylinder segments together to form said cylindrical section.

### Claim 13 (depends on 11)

A method as described in claim 11, wherein said plurality of stiffening protrusions comprises: a plurality of spiral ridges formed on of said partial cylinder segments.

### Claim 14 (depends on 13)

A method as described in claim 13, wherein said plurality of spiral ridges are configured to generate a rifled flow through said duct section.

### Claim 15 (depends on 11)

A method as described in claim 11, wherein said plurality of stiffening protrusions comprises: a plurality of ribbed ridges formed on said cylindrical section.

### Claim 16 (depends on 15)

A method as described in claim 15, wherein said plurality of ribbed ridges are configured to: generate a localized turbulent buffer zone immediately adjacent an inner surface of said cylindrical section; and generate a central laminar flow zone through said duct section.

### Claim 17

An aerospace duct element comprising: at least two partial cylinder duct segments formed during a single build run within a direct fabrication technology build chamber, said at least two partial cylinder duct segments orientated within said build chamber in a nested arrangement during said single build run, said at least two of said partial cylinder duct segments assembled to form a duct section, said duct section having a duct cross-sectional profile larger than a build chamber profile; said partial cylinder duct segments comprising a plurality of protrusions formed on an inner surface of said partial cylinder duct segments during said single build run, said plurality of protrusions stiffening said duct section and modifying flow through said duct section.

### Claim 18 (depends on 17)

An aerospace duct element as described in claim 17, wherein said plurality of stiffening protrusions comprises a plurality of spiral ridges configured to generate a rifled flow through said duct section.

### Claim 19 (depends on 17)

An aerospace duct element as described in claim 17, wherein said plurality of stiffening protrusions comprises a plurality of ribbed ridges configured to: generate a localized turbulent buffer zone immediately adjacent said inner surface and generate a central laminar flow zone through said duct section.