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Publication numberUS3924793 A
Publication typeGrant
Publication dateDec 9, 1975
Filing dateJul 22, 1974
Priority dateJul 24, 1973
Publication numberUS 3924793 A, US 3924793A, US-A-3924793, US3924793 A, US3924793A
InventorsSummers Leo Ewart Arthur, Underhill David Sidney
Original AssigneeBritish Aircraft Corp Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Forming metals
US 3924793 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

O Unlted States Patent 1191 1111 3, 93 Summers et al. Dec. 9, 1975 FORMING METALS 3,200,489 8/1965 Keeleric 29/497.5 x 3,206,847 9/1965 Keeleric 29/480 [75] Inventors- Ewart Summers, Dav! 3,340,101 9/1967 Fields et al 72/364 ux g i gndelhlll, both of Bnstol, 3,345,735 10/1967 Nicholls 29/471.1 x

ng an OTHER PUBLICATIONS [73] Assignee: British Aircraft curporation Backofen Superplasticity Enchants Metallurgy Steel Ltmlted, London, England Dec 15 1969 PP 2548. [22] Filed: July 22, 1974 [21] Appl 490,887 Primary Examiner-Jarhes L. Jones, Jr.

Assistant Examiner-K. J. Ramsey Attorney, Agent, or FirmCushman, Darby & [30] Forelgn Appllcatlon Prlorlty Data Cushman July 24, 1973 United Kingdom 35293/73 57 ABSTRACT [52] US. Cl. .1 228/157; 72/364; 228/181 1 [51] Int. B23K 31/00, 8211) 47/00 A method of formmg a stlffened panel In whlch an 1n- [58] Field 61 Search 2 9/471.1 480 197 5 497 7' erior Sheet a superplastic material is Placed h 8 tween two face sheets and attached one to the other in alternate sequence so that, as the face sheets are [56] References Cited moved apart, the attached regions of the interior sheet UNITED STATES PATENTS are drawn them 2,481,046 9/1949 Scurlock 29/471.1 ux 7 8 Drawmg F'gures US. Patent Dec. 9, 1975 Sheet 1 of 2 3,924,793

5 94- 7 A E b 5 US. Patent Dec. 9, 1975 Sheet 2 of2 3,924,793

roRMiNo METALS This invention relates to the forming of stiffened panels of metallic alloys having super-plastic characteristics. Metallic alloys having super-plastic characteristics have a composition and microstructure such that, when heated to within an appropriate range of temperature and when deformed within an appropriate range of strain rate, they exhibit the flow characteristics of a viscous fluid. Such alloys have characteristics indicated by the formula: f= h s"- where:-

m is numerically of the order of 0.7 to 1.00,

f is applied stress (load per unit area),

h is a constant,

3 is strain rate (extension per unit of original length per unit of time), and,

m is the strain rate sensitivity.

The condition in which these characteristics are attained is known as super-plasticity and large deformations are possible without fracture.

The invention has for an object the ready formation of stiffened panels with a minimum of forming operations.

According to the present invention a method of forming a stiffened panel includes the steps of positioning a metal face sheet on each side of an interior sheet of a metallic alloy having superplastic characteristics, attaching spaced regions of the said interior sheet alternately to the face sheet on one side and to the face sheet on the other side of the interior sheet, bringing the assembly to within that temperature range at which the interior sheet exhibits superplastic characteristics, and causing the face sheets to be moved apart and thus to draw the attached regions of the interior sheet with them such that the said interior sheet finally extends from one face sheet to the other in alternate sequence.

Conveniently, the metal face sheets have their peripheral edges sealingly joined together and the envelope so formed is inflated to urge the said face sheets apart.

Somepreferred embodiments of the invention are now described with reference to the accompanying drawings:

FIG. 1 is a scross-sectional view of parts of the components of a panel before forming,

FIG. 2 is a similar view to that of FIG. 1 subsequent to forming,

FIG. 3 is a similar view to that of FIG. 2 but illustrating an alternative embodiment.

FIG. 4- is a similar view to that of FIG. 1 also illustrating an alternative embodiment,

FIG. 5 is a similar view to that of FIG. 4 subsequent to forming,

FIG. 6 is a similar view to that of FIG. 5 but showing an alternative embodiment, and,

FIGS. 7 and 8 illustrate a sealed peripheral edge ofa panel respectively before and after forming.

Referring to FIGS. I and 2, a stiffened panel is formed of three metal sheets, two face sheets 1 and 2, respectively, and an interior sheet 3, which is of a superplastic alloy. The interior sheet is placed between the two face sheets 1 and 2 with spacer portions d in the form of strips of metal placed between each face sheet I and 2 and the interior sheet 3. The spacer portions are placed where the sheets are to be attached one to theother in alternate sequence, that is to say from the left hand edge of FIG. 1 the sheets I and 3 have a spacer portion 4 and then the sheets 2 and 3 and so on. The assembly is then subjected to heat and pressure so that those regions of the sheets at the spacer portions become diffusion bonded to the spacer portions 4 and thereby indirectly one to another.

In the alternative of FIG. 3, the elongated spacer portions 4 are replaced by spacer portions in the form of small disc-like portions 5. These are spaced in alternate sequence between the face sheet 1 and the interior sheet 3 and between the face sheet 2 and the interior sheet 3. Again, the sheets are diffusion bonded to the spacer portions 5 and hence indirectly to one another.

FIGS. 4, 5 and 6 are similar to FIGS. 1, 2 and 3, respectively, but illustrate embodiments where the face sheets 1 and 2 are attached directly to the interior sheet 3 without the spacer portions d or 5 being present. In this case the sheets I and 2 are locally attached to the sheet 3 by welded regions. The welded regions, which in FIG. 5 are in the form of lines 6 and in FIG. 6 are in the form of spots 7, are preferably provided by an electron beam welding process.

To bring the assembly from the condition of FIGS. 1 and 4 to that of FIGS. 2 and 5 or 3 and 6 respectively, it is brought to within the temperature range at which the interior sheet exhibits superplastic characteristics, if it is not already in that range, and the face sheets 1 and 2 are moved apart thus drawing the attached regions of the interior sheet (that is those regions adjacent the spacer portions 4 or 5 and adjacent the weld regions 6 or 7) with them in alternately opposite directions. The interior sheet 3 thus becomes of corrugated form (as in FIGS. 2 and 5) or of dimpled form (as in FIGS. 3 and 6). As can be seen in FIGS. 3 and 6, the sheet 3 becomes a series of alternate oppositely facing dimples. In both cases the interior sheet 3 zig-zags between the face sheets 1 and 2 bridging the void be tween them.

FIGS. 7 and 8 illustrate how the sheets can be subjected to a welding operation around their peripheries to form a sealed envelope. The weld region is shown at 8. The sealed envelope so formed is fed with an inert gas under pressure such that, when the interior sheet 3 is superplastic, the sheets 1 and 2 are moved apart by a predetermined amount to effect the previously described corrugation or dimpling of the interior sheet.

To maintain flat outer surfaces, the sheets 1 and 2 may be moved apart against oppositely facing plattens of a press (not shown). To further aid the maintaining of flat outer surfaces, the interior sheet may be of thinner gauge material than the face sheets.

The face sheets I and 2 may also be of a superplastic alloy; this arrangement has advantage where the finished panel required to be of other than a totally flat formation.

We claim:

l. A method of forming a stiffened panel including the steps of positioning a metal face sheet on each side of an interior sheet of a metallic alloy having superplastic characteristics, attaching spaced regions of the said interior sheet alternately to the face sheet on one side and to the face sheet on the other side of the interior sheet, sealing the said face sheets one to the other to form an inflatable envelope assembly, bringing the assembly to within that temperature range at which the interior sheet exhibits superplastic characteristics, and applying a differential pressure between the interior and the exterior of the envelope assembly thus causing the face sheets to move apart and draw the attached regions of the interior sheet with them so that the said interior sheet finally extends from one face to the other in alternate sequence.

2. A method according to claim 1 wherein the spaced attachment regions of the interior sheet are indirectly attached to the face sheets by means of metallic spacer portions metallurgically bonded both to a face sheet and to the interior sheet.

3. A method according to claim 1 wherein the spaced regions of the interior sheet are directly attached to the face sheets by means of a metallurgical bond.

claiml.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2481046 *Nov 13, 1947Sep 6, 1949Western Engineering AssociatesPanel structure
US3200489 *Jun 18, 1957Aug 17, 1965Keeleric George FMethod of making honeycomb core
US3206847 *Mar 16, 1962Sep 21, 1965Keeleric George FMethod for joining metal pieces at spaced intervals
US3340101 *Apr 2, 1965Sep 5, 1967IbmThermoforming of metals
US3345735 *Feb 25, 1963Oct 10, 1967Nicholls Augustus HHoneycomb core construction through the application of heat and pressure
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4292375 *May 30, 1979Sep 29, 1981The United States Of America As Represented By The Administrator Of The National Aeronautics And Space AdministrationSuperplastically formed diffusion bonded metallic structure
US4304821 *Sep 28, 1979Dec 8, 1981Mcdonnell Douglas CorporationUsing a metal alloy
US4351470 *Jul 1, 1981Sep 28, 1982British Aerospace Public Limited CompanyMethod of making a stiffened panel
US4393987 *Sep 30, 1981Jul 19, 1983The Boeing CompanySuperplastically formed structure and method of making
US4538756 *Jun 10, 1983Sep 3, 1985Texas Instruments IncorporatedProcess for producing reinforced structural members
US4769968 *Mar 5, 1987Sep 13, 1988The United States Of America As Represented By The Administrator Of The National Aeronautics And Space AdministrationTruss-core corrugation for compressive loads
US5118571 *Dec 21, 1990Jun 2, 1992Ltv Aerospace And Defense CompanyInjecting pressurized gas through tubes; diffusion bonding
US5156327 *Apr 2, 1991Oct 20, 1992Mitsubishi Jukogyo Kabushiki KaishaProcedure for molding composite materials
US5287918 *Feb 24, 1993Feb 22, 1994Rolls-Royce PlcHeat exchangers
US5344063 *Sep 28, 1992Sep 6, 1994British Aerospace Public Limited CompanyMethod of making diffusion bonded/superplastically formed cellular structures with a metal matrix composite
US5385204 *Sep 8, 1993Jan 31, 1995Rolls-Royce PlcHeat exchanger and methods of manufacture thereof
US5410132 *Oct 15, 1991Apr 25, 1995The Boeing CompanySuperplastic forming using induction heating
US5437936 *Sep 14, 1992Aug 1, 1995Johnson; Jeffrey D.Honeycomb core structure and method and apparatus relating thereto
US5505256 *Mar 27, 1995Apr 9, 1996Rolls-Royce PlcHeat exchangers and methods of manufacture thereof
US5587098 *Jun 7, 1995Dec 24, 1996The Boeing CompanyJoining large structures using localized induction heating
US5609288 *Jun 6, 1995Mar 11, 1997Johnson; Jeffrey D.Honeycomb core structure and method and apparatus relating thereto
US5624594 *Jun 6, 1995Apr 29, 1997The Boeing CompanyFixed coil induction heater for thermoplastic welding
US5641422 *Jun 16, 1995Jun 24, 1997The Boeing CompanyForming fusion welds using fixed solenoid coil induction heater
US5645744 *Jun 6, 1995Jul 8, 1997The Boeing CompanyAt least two metal sheets surrounding workpiece, means for temporarily sealing sheets around workpiece
US5683607 *Aug 14, 1996Nov 4, 1997The Boeing CompanyRapid heating and controlled cooling in a single cycle in an induction heating press using an actively cooled induction coil embedded in a ceramic die set
US5687900 *Mar 28, 1995Nov 18, 1997Mcdonnell Douglas CorporationStructural panel having a predetermined shape and an associated method for superplastically forming and diffusion bonding the structural panel
US5700995 *Mar 17, 1995Dec 23, 1997The Boeing CompanySuperplastically formed part
US5705794 *May 26, 1995Jan 6, 1998The Boeing CompanyCombined heating cycles to improve efficiency in inductive heating operations
US5710414 *Jun 6, 1995Jan 20, 1998The Boeing CompanyFor counteracting sagging during thermoplastic welding
US5723849 *Jun 6, 1995Mar 3, 1998The Boeing CompanyReinforced susceptor for induction or resistance welding of thermoplastic composites
US5728309 *Jun 6, 1995Mar 17, 1998The Boeing CompanyMethod for achieving thermal uniformity in induction processing of organic matrix composites or metals
US5793024 *Jun 6, 1995Aug 11, 1998The Boeing CompanyBonding using induction heating
US5797239 *Jan 13, 1997Aug 25, 1998Mcdonnell Douglas CorporationTitanium reinforced structural panel having a predetermined shape
US5808281 *Jun 6, 1995Sep 15, 1998The Boeing CompanyFor temperature control of a workpiece in induction heating operations
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US5847375 *Jul 19, 1996Dec 8, 1998The Boeing CompanyFastenerless bonder wingbox
US5914064 *Jul 9, 1997Jun 22, 1999The Boeing CompanyCombined cycle for forming and annealing
US5955207 *Nov 24, 1997Sep 21, 1999Mcdonnell Douglas CorporationStructural panel having boron reinforce face sheets and associated fabrication method
US5994666 *Dec 20, 1996Nov 30, 1999The Boeing CompanyMultisheet metal sandwich structures
US6040563 *Dec 22, 1997Mar 21, 2000The Boeing CompanyBonded assemblies
US6087640 *May 26, 1995Jul 11, 2000The Boeing CompanyForming parts with complex curvature
US6508394Aug 31, 1999Jan 21, 2003The Boeing CompanyMethod for making multisheet metal sandwich structure with throughholes
US6656603Jun 6, 2002Dec 2, 2003The Boeing CompanyMultisheet sandwich structures with throughholes
US6914225Jun 18, 2003Jul 5, 2005The Boeing CompanyApparatus and methods for single sheet forming using induction heating
US7126096Jun 6, 1995Oct 24, 2006Th Boeing CompanyResistance welding of thermoplastics in aerospace structure
US7146727 *Nov 1, 2004Dec 12, 2006The Boeing CompanyMultisheet sandwich panel using superplastic forming and adhesive bonding
CN101611286BFeb 22, 2008Mar 9, 2011皮埃尔·维罗洛;贝尔纳·苏斯;皮埃尔·阿菲斯彻;弗里德里克·卡拉马诺;帕斯卡尔·卡泽雷斯;阿兰·阿夫里Method of making a heat exchanger and heat exchanger obtained according to this method
EP0962268A1 *Jun 1, 1999Dec 8, 1999Solistor B.V.A method for manufacturing a storage vessel for storing a medium, as well as a storage vessel manufactured in accordance with this method
EP2110189A1 *Apr 18, 2008Oct 21, 2009ETH ZürichMethod for dieless forming of sheet metal
WO2008125755A2 *Feb 22, 2008Oct 23, 2008Pierre VironneauMethod of making a heat exchanger and heat exchanger obtained according to this method
Classifications
U.S. Classification228/157, 228/181, 72/364
International ClassificationB23K20/00
Cooperative ClassificationB23K20/00
European ClassificationB23K20/00
Legal Events
DateCodeEventDescription
Feb 5, 1982ASAssignment
Owner name: BAC AND BRITISH AEROSPACE, BROOKLANDS RD., WEYBRID
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BRITISH AIRCRAFT CORPORATION LIMITED,;REEL/FRAME:003957/0227
Effective date: 19811218
Feb 1, 1982ASAssignment
Owner name: BRITISH AEROSPACE PUBLIC LIMITED COMPANY
Free format text: CHANGE OF NAME;ASSIGNOR:BRITISH AEROSPACE LIMITED;REEL/FRAME:004080/0820
Effective date: 19820106
Owner name: BRITISH AEROSPACE PUBLIC LIMITED COMPANY, DISTRICT