The invention is directed to a multi-segment tool and method for vacuum forming a composite part in general, and more specifically a tool and method relating to composite formation of an aircraft nacelle and related parts.
Aircraft structures have many components that have complex shapes with multiple curvatures. For example, various complex shapes are found in aircraft nacelle and pylon systems, thrust reversers and rocket thruster chambers, among others. Several methods are known to form complex shapes. For thermoplastic and thermoset polymers, multiple tools can be used in injection and compression molding operations to form complex shapes. Metal forming techniques have used casting plugs to facilitate the formation of metallic rocket thrust chambers having hour-glass configurations. These methods, however, are not readily adaptable for forming complex parts using vacuum bag composite techniques.
Vacuum bag forming is a method of composite fabrication that can be used to form complex shapes using multiple tools. In vacuum bag forming, a vacuum pulls a preform around the contours of a tool. Where multiple tools are used to form composite parts, there must be sufficient vacuum sealing between the tools. Vacuum integrity and proper tool alignment is important to achieve desired end-product form and properties. Because the vacuum pulls a preform into every contour, seam defects result if there is less than precise alignment between the tools. Mechanical fasteners such as bolts and the like have attempted to ensure alignment among multiple tools. Such systems, however, can be cumbersome, costly and inadequate to minimize seam defects. In terms of vacuum integrity, gaskets, o-rings and similar devices have been used to improve vacuum integrity between adjacent tools. These attempts often result in less than full vacuum integrity leading to possible product defects, poor resin cure and poor resin-to-matrix migration, contributing to potential product deficiencies. In response, some have attempted to use multiple vacuum barriers to ensure vacuum integrity, but such solutions increase processing complexity and cost.
A need has arisen for the ability to form multiple curvature composites, either integrally formed or formed with minimal sub-parts, where the seams are minimized, sufficient vacuum integrity is achieved and misalignment of tools is reduced. Further, there is a need for an efficient method of forming complex shapes while providing flexibility to accommodate changing design constraints.
A multi-segment tool for vacuum forming a composite part can include a first tool having a first surface and a second surface. A second tool can have an opening. The second tool can be capable of receiving the first tool through the opening. A second tool can be further capable of being positioned on the first tool in a location other than the first surface or second surface. The first tool can receive at least a portion of a preform composite. The second tool can receive at least a portion of the preform composite. The first tool can have a vacuum barrier attached to the first surface and to the second surface, wherein a vacuum barrier encapsulates the preform composite and the second tool.
A tooling system for vacuum forming a composite part can include a first tool having a core and a base with the core extending upwards from the base. A second tool can be positioned upon the core in such a way that a portion of the core extends above the second tool. The tooling system can further include a composite formed on the first tool and the second tool, the composite having a complex shape. A vacuum barrier can be pressure sealed to the base and to the portion of the core that extends above the second tool. The vacuum barrier can be capable of forming a pressure seal that includes the composite, the first tool and the second tool.
A method of forming a composite part can include providing a first tool and positioning a second tool on a first tool. The second tool can have an opening capable of receiving the first tool through the opening. A method can include applying a composite preform on at least a portion of the second tool. A method can include vacuum sealing the composite preform by securing a vacuum barrier to the first tool while the preform and second tool can be encapsulated within a vacuum barrier. A method can further include curing the preform to form a composite part.
The foregoing and other features, aspects and advantages of the invention will be apparent from a reading of the following detailed description together with the accompanying drawings, which are described below.
Certain exemplary embodiments of the present invention are described below and illustrated in the accompanying Figures. The embodiments described are only for purposes of illustrating embodiments of the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications and improvements of the described embodiments, will occur to those of skill in the art, and all such alternate embodiments, modifications and improvements are within the scope of the present invention.
The tool and method in general comprises two or more tools that can mate with one another to form a desired mold profile. Composite materials are then applied upon or laid up on the tools. The composite can be then encased within a vacuum barrier or bag, which can be sealed around the composite and secured to surfaces of one of the tools. After curing, the parts can be selectively removed, resulting in a composite structure having a complex shape. In a preferred embodiment, a 360 degree complex shape can be produced for use as, for example, a one-piece inner barrel of an aircraft engine nacelle.
More specifically, a first embodiment for a tool or system for vacuum forming a composite part is shown in
First tool 30 can have outer shape profiles designed as necessary to conform to the desired composite part and/or to mate with additional tools. Bottom portion 36 can have bottom side 37 that extends upward and inwardly from bottom edge 38. Similarly, top portion 32 can have an alignment bevel 33 that also slopes upward and inwardly towards top edge 34. Alignment bevel 33 can also facilitate tool alignment. To facilitate removal of tool(s) and/or composite part(s), alignment bevel 33 and bottom side 37 preferably have right (90°) or acute (less than 90°) angles θ1, θ2, respectively, (as shown in
First tool 30 has an alignment ridge 35 as shown, for example, in
As shown in
As shown in
First and second tools 30, 40 can be formed from a variety of non-metallic materials such as composites or metallic alloys such as, for example, aluminum, nickel, iron, steel or a substantially inexpansible alloy, such as Invar® nickel steel alloy, as needed. Selection of a tool material typically is based on forming method, composite part tolerances, number of curing and/or heating cycles, coefficient of thermal expansion of the tooling material, desired or required surface condition of the composite part, composite constituents, and cost, as is generally known in the art. In a preferred embodiment, the tools are formed of Invar® alloy.
The composite part 16, which sometimes is called a preform prior to curing, is typically comprised of a reinforcement and a matrix. Reinforcements can be carbon, aramid fibers, para-aramid fibers, glass fibers, silicon carbide fibers, high strength polyethylene or other composite fiber materials as is known in the art. The reinforcement material can be short or long fibers, woven, laid-up reinforcements, laminates or any combination thereof. The matrix can be a thermoset or thermoplastic polymeric resin such as polyester, vinyl ester, epoxy, phenolic, polyimide, polyamide, polypropylene, PEEK or baselimide. In a preferred embodiment, the reinforcement is graphite and the matrix is epoxy.
Vacuum barrier 20 can be a flexible polymeric material, or other material as is known in the art, sufficient to withstand temperatures and pressures encountered with vacuum bag composite curing. A vacuum is drawn from the space between vacuum barrier 20 and multi-segment tool 10 using a vacuum source (not shown) such as a compressor or venturi pump as is known in the art. Pressure approaching approximately one atmosphere forces composite part 16 against the outer profile 12 of multi-segment tool 10.
After securing the vacuum barrier 20 and achieving the desired pressure conditions, the composite part 16 is then cured. Cure, or curing, as used herein, refers to the process that results in cross-linking or solidification of a matrix and reinforcement. Curing can occur in pressurized vessels at elevated temperatures in devices such as an autoclave, as is known in the art. In an alternate embodiment, curing can occur at ambient temperature and/or atmospheric pressures. Multiple cures cycles can be used as the need may arise. For example, a preform can undergo a first and second cure to form composite part 16. In one example using the tool described herein, a woven carbon fiber-epoxy composite part 16 was exposed to about 350° F. simultaneously with pressures ranging between about 35 psi to about 100 psi, preferably from about 70 to 80 psi, for about 120 minutes inside an autoclave. The particular temperature-pressure-time variable can be adjusted according to the particular reinforcement and matrix combination used in the preform, as is known in the art.
A second embodiment of a tool or system for forming a composite part is shown in
Referring to
Second tool 140 has a top edge 142 and bottom edge 144. Bottom edge 144 is generally circular and planar. As shown, top edge 142 also is shown generally non-parallel to the plane formed by bottom edge 144. The use of such a non-parallel interface, also called a spline form split line, can assist in removal of the composite from the tool following curing. In practice, various non-parallel interfaces can be used, but preferably the angle between the interfaces will be greater than about five degrees. Bottom profile 145 defines the surface to which a preform will later be partially applied, as discussed below.
In the assembled condition, multi-segment tool 110 comprises first tool 130, second tool 140 and third tool 160, assembled together. Lower profile 145 is mated to upper profile 165, and together form a surface to which a composite preform can be placed.
This invention permits more than one removable piece of tooling to be used in conjunction with other tools, without the requirement of vacuum sealing surfaces between the tools. A vacuum barrier can be sealed to a single structure, and capture any intermediate tools along with the preform or composite. This eliminates the need to have sealing surfaces between removable tools, thereby minimizing leak exposure and the number of resulting seams. This method is advantageous for 360 degree tooling applications, but also can be used in other non-360 degree applications. Since intervening pressure seals are not required, the interfaces between upper and lower parts can be made with greater mechanical tolerances.
In addition, the use of minimal components ensure proper alignment as described above, which often is a problem with multi-segmented bond tooling. The use of indexes helps ensure accurate mating or clocking of tool sections and profiles.
Embodiments of this invention provide many advantages over prior art methods. Since the vacuum barrier is attached to portions (e.g., top and bottom as shown in embodiments) of a first tool that is itself vacuum-tight, the lower profile (e.g., element 145) and upper profile (e.g., element 165) of the embodiments that receive the preform need not be vacuum-tight. Hence the lower profile and upper profile (when combined, sometimes called in the art a “facesheet”) can accommodate tool holes, through bushings, and other discontinuities that often are needed for mechanical assembly, tool replacement and cleaning. Hence, the facesheet can have greater tolerances for machined parts, and broader standards for welding around holes and projections that otherwise would increase tool manufacturing complexity. Such tolerances, through holes and other often minor incongruities in the facesheet have limited negative impact on vacuum integrity. This advantage simplifies overall tool construction and allows for more efficient tool turnaround and cleaning following use.
The above descriptions of various embodiments of the invention are intended to describe and illustrate various elements and aspects of the invention. Persons of ordinary skill in the art will recognize that certain changes and modifications can be made to the described embodiments without departing from the scope of the invention. All such changes and modifications are intended to be within the scope of the appended claims.
This application is a divisional of U.S. application Ser. No. 12/263,915 filed Nov. 3, 2008, the content of which is incorporated by reference in its entirety.
Number | Name | Date | Kind |
---|---|---|---|
1835986 | Heston | Dec 1931 | A |
2586300 | Campbell | Feb 1952 | A |
3081705 | Wamken | Mar 1963 | A |
3633267 | Deminet et al. | Jan 1972 | A |
3646185 | Jennings | Feb 1972 | A |
3646186 | Jennings | Feb 1972 | A |
3768954 | Marsh et al. | Oct 1973 | A |
3957416 | Kaempen | May 1976 | A |
4122672 | Lowrie | Oct 1978 | A |
4177032 | Selden | Dec 1979 | A |
4278490 | Pistole et al. | Jul 1981 | A |
4288277 | Siilats | Sep 1981 | A |
4341368 | Thompson et al. | Jul 1982 | A |
4429824 | Woodward | Feb 1984 | A |
4436574 | Long et al. | Mar 1984 | A |
4462787 | Bogardus et al. | Jul 1984 | A |
4525132 | Williams | Jun 1985 | A |
4610422 | Kraiss | Sep 1986 | A |
4693678 | Von Volkli | Sep 1987 | A |
4861247 | Schimanek | Aug 1989 | A |
4942653 | Hawkinson | Jul 1990 | A |
4954209 | Baron | Sep 1990 | A |
5022845 | Charlson et al. | Jun 1991 | A |
5122323 | Sullivan | Jun 1992 | A |
5193737 | Carraher | Mar 1993 | A |
5199631 | Anderson et al. | Apr 1993 | A |
5226997 | Vallier | Jul 1993 | A |
5228374 | Santeramo | Jul 1993 | A |
5266137 | Hollingsworth | Nov 1993 | A |
5304057 | Celerier et al. | Apr 1994 | A |
5477913 | Polk et al. | Dec 1995 | A |
5597435 | Desautels et al. | Jan 1997 | A |
5613299 | Ring et al. | Mar 1997 | A |
5768778 | Anderson et al. | Jun 1998 | A |
5773047 | Cloud | Jun 1998 | A |
6123170 | Porte et al. | Sep 2000 | A |
6308408 | Myers | Oct 2001 | B1 |
6330792 | Cornelius et al. | Dec 2001 | B2 |
6458309 | Allen et al. | Oct 2002 | B1 |
6723272 | Montague et al. | Apr 2004 | B2 |
6755280 | Porte et al. | Jun 2004 | B2 |
6997429 | Meinrad | Feb 2006 | B2 |
7125237 | Buge et al. | Oct 2006 | B2 |
7166251 | Blankinship | Jan 2007 | B2 |
7410352 | Sarh | Aug 2008 | B2 |
7497679 | Mamada | Mar 2009 | B2 |
7624488 | Lum | Dec 2009 | B2 |
7640961 | Stubner et al. | Jan 2010 | B2 |
7707708 | Douglas et al. | May 2010 | B2 |
7861394 | Douglas et al. | Jan 2011 | B2 |
20020104606 | Ohzuru et al. | Aug 2002 | A1 |
20020135090 | Koren | Sep 2002 | A1 |
20030025232 | Slaughter et al. | Feb 2003 | A1 |
20040013762 | Bianchini | Jan 2004 | A1 |
20040070108 | Simpson et al. | Apr 2004 | A1 |
20040207108 | Pacchiana et al. | Oct 2004 | A1 |
20060225265 | Burnett et al. | Oct 2006 | A1 |
20080116607 | Miedema | May 2008 | A1 |
20080246175 | Biornstad et al. | Oct 2008 | A1 |
Number | Date | Country |
---|---|---|
1262570 | Mar 1968 | DE |
1504597 | May 1969 | DE |
2259690 | Jun 1974 | DE |
2352373 | Apr 1975 | DE |
2652862 | Apr 1978 | DE |
0184759 | Jun 1986 | EP |
1767325 | Mar 2007 | EP |
9214672 | Sep 1992 | WO |
2009150401 | Dec 2009 | WO |
Entry |
---|
American Solving, Inc., “Rig Set Modular Air Bearing System”[online], retrieved from the Internet: http://www.solvinginc.com/rig—set—modular-Air—bearing—system.htm>, [Retrieved on Mar. 15, 2007 by the EPO]; p. 1-p. 2. |
Partial European Search Report in EP Appln. No. 06019100.4-1253 dated Feb. 5, 2007. |
Extended EP Search Report in EP Appln. No. 06019100.4 dated Apr. 2, 2007. |
European Extended Search Report and European Search Opinion in EP Appln No. 09013714.2, issued Mar. 4, 2010. |
Number | Date | Country | |
---|---|---|---|
20110308723 A1 | Dec 2011 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 12263915 | Nov 2008 | US |
Child | 13217709 | US |