The Boeing Company

Edward Litwinski

Juan M Valdez

Steven Glenn Keener

Rahmatollah Fakhri Toosky

Charles D Rosen

Leo Delangis

Bert E Syms

Rahmatollah F Toosky

A rivet having improved formability is provided. The rivet has a shank having a head at one end. The shank and the head have a refined grain structure. The rivet is manufactured from the region of the workpiece having a refined grain structure by first forming a region having a refined grain structure in a workpiece and then forming the rivet. The refined grain structure results in improved mechanical properties, such as formability, strength, toughness, ductility, corrosion resistance, and fatigue resistance. The improved formability of the rivet reduces the formation and propagation of cracks during the manufacture and installation of the rivets.

Rivets having high strength and formability

The apparatus for operating on a workpiece includes a die defining first and second apertures and an interior therebetween. The first aperture and the interior of the die are structured to receive the workpiece. The interior of the die can be structured to shape the workpiece into a predetermined configuration. The apparatus includes at least one rotatable pin extending at least partially into the interior of the die. The pin is structured to at least partially stir the workpiece as the workpiece moves through the interior of the die to thereby refine the grain structure of the workpiece.

Method and apparatus for producing a refined grain structure

Method of manufacturing rivets having high strength and formability

A precipitation hardened structural assembly is provided, including a first structural member and a second structural member positioned adjacent to the first structural member such that the first and second structural members define an interface therebetween. At least one friction stir weld joint joins the first structural member to the second structural member at least partially along the interface. The first and second structural members and the friction stir weld joint are solution heat treated at a first predetermined temperature schedule and precipitation heat treated at a second predetermined temperature schedule and wherein the friction stir weld joint comprises a refined grain structure having grain size of less than about 5 microns.

High strength friction stir welding

A method for preparing ultra-fine grain titanium or titanium-alloy articles used for adjoining or assembling of detail components. Coarse-grained titanium or titanium-alloy materials typically are heated and forced under constant pressure through a friction stir processing tooling device containing a stirring chamber and a stirring rod. As the material is passed through the stirring chamber, the stirring rod solutionizes the titanium or titanium-alloy material and stirs the material to obtain a homogeneous or uniform material condition. As the processed material exits the stirring chamber of the friction stir process tooling device, it reconsolidates as an extremely homogeneous structure possessing ultra-fine grain structure. Titanium or titanium-alloy materials having been processed to achieve such ultra-fine grain material structure may then be manufactured into aerospace structural articles or components such as fasteners or articles that do not require a subsequent thermal or heat-treatment steps. The resulting fasteners, articles or components have improved material performance characteristics associated with this ultra-fine grain material structure.

Method for preparing ultra-fine grain titanium and titanium-alloy articles and articles prepared thereby

A back-up tooling apparatus for supporting the inner side of a hollow cylindrical workpiece during a circumferential friction stir weld includes a plurality of arcuate shoes configured to mate end-to-end to form a substantially continuous ring, and an expandable support for supporting the shoes and operable to retract and expand the shoes inward and outward. The expandable support includes at least one rotatable feed screw and central support members mounted on the feed screw or screws and pivotally connected to the shoes by support arms. The central support members are moved axially toward or away from each other for expanding or retracting the shoes. The shoes in one embodiment overlap in the circumferential direction, and a seal material is disposed between mating end faces of adjacent shoes. A restraining device is provided for clamping about the workpiece to reduce thermal expansion thereof. Cable-and-winch and geared drive devices are provided for rotatably driving the workpiece from its outer surface.

Tooling and methods for circumferential friction stir welding

The present invention provides a self-backing friction stir welding tool for backing up weld joints formed by friction stir welding large workpieces and workpieces having curvilinear geometries. The backing device includes a rotatable shoulder adapted to at least partially engage the weld joint and a probe having first and second ends and an intermediate portion therebetween. At least a portion of the intermediate portion of the probe frictionally engages the workpiece to form the weld joint. The first end of the probe defines a backing member, at least a portion of which engages the weld joint opposite the rotatable shoulder. The second end of the probe is adapted to rotatably and axial translatably communicate with the rotatable shoulder to thereby rotate the probe and urge the backing member toward the weld joint, thus constraining the plasticized material within the weld joint. The backing member can include an anchor and a support member, at least a portion of which engages the weld joint opposite the rotatable shoulder. The support member defines a recess for receiving the anchor and wherein the anchor urges the support member toward the workpiece. The support member can include at least one pair of rollers that are rotatable such that the support member is movable relative to the workpiece.

Method and apparatus for backing up a friction stir weld joint

The present invention provides a novel pin design for a friction stir welding (FSW) tool that can penetrate more deeply into workpieces to form a thicker weld joint without overloading the tool. The pin is provided with threads on its surface. Some portions of the threads are in a positive hand (d,, d,); positive threads screw in to draw the pin into workpieces when the pin is rotated. Other portions of the threads are in a negative hand (d,, d,); negative threads screw out to oppose drawing-in of the pin. When the pin is rotated and driven into workpieces under an applied vertical load, the positive threads encourage penetration of the pin into the workpieces while the negative threads enhance shearing of workpiece material into particles. The positive threads thus reduce the amount of vertical load required to drive the pin, and therefore allow the pin to penetrate more deeply into workpieces to form a thicker weld joint without overloading the tool. Preferably, the pin diameter is decreased from its proximal end (d,) to its distal end (d,), either discretely in steps or linearly in a tapering manner. The reducing profile of the pin further eases penetration of the pin into workpieces, and also reduces the amount of transverse welding load required to traverse the pin along the weld interface.

FSW tool design for thick weld joints

The present invention provides novel joint designs and methods for holding together and drawing together interface edges of workpieces during friction stir welding. The method includes providing an interface edge (30A) on a first workpiece (20A), and an interface edge (30B) on a second workpiece (20B) that is complementary with the interface edge of the first workpiece. The interface edges cooperate with consumable pins (38) to hold the first and second workpieces together. In a preferred embodiment, the interface edges cooperate to draw the first and second workpieces together when a load in a direction normal to the interfaces is applied along the mated interfaces.

Friction stir welding interlocking joint design and method

The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

Growing community of inventors

Mission Viejo, CA, United States of America

Edward Litwinski