Friction plug welding

Details Friction plug welding Friction plug welding

1998-08-26

2001-04-10

Ryan, Patrick (Department: 1725)

Metal fusion bonding

Process

Using dynamic frictional energy

C228S113000, C228S114000, C228S114500, C228S001100, C228S002100

Reexamination Certificate

active

06213379

ABSTRACT:

REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to friction welding. More particularly, the present invention relates to friction plug welding.
2. General Background of the Invention
Friction plug welding (FPW), also referred to as plug welding and friction taper plug welding (FTPW), is a process in which initial defective weld material is located, removed and replaced by a tapered plug, which is friction welded into place. This process is similar to friction stud welding, in which a plug is welded to the surface of a plate, end of a rod, or other material. The primary difference is that FPW is designed to replace a relatively large volume of material containing a defect whereas friction stud welding is a surface-joining technique.
Friction plug welding could be used to repair weld defects in a wide variety of applications; however, it would most likely be used where weld strength is critical. This is due to the fact that manual weld repairs result in strengths much lower than original weld strengths, as opposed to friction plug welds (FPWs) whose typical mechanical properties exceed that of the initial weld. In applications where high strength is not required, manual welding would be less expensive and would not require specialized equipment.
An extension of FPW is known as stitch welding or friction tapered stitch welding (FTSW) and has been developed to repair defects longer than what a single plug can eliminate. Stitch welding is the linear sequential welding of several plugs such that the last plug weld partially overlaps the previous plug. Defects of indefinite length can be repaired with this process, limited only to the time and cost of performing multiple plug welds. These welds have undergone the same testing procedures as single FPWs, including NDI and destructive evaluation. The strengths for stitch welds are similar to those for single plug welds.
Stagger stitch welding is a process best defined as stitch welding in a non-linear fashion. Areas wider than one plug length can be completely covered by staggering plugs side to side as they progress down the length of an initial weld. This process is being developed for plug welds whose minor diameter is on the crown side of the initial weld, and where replacement of the entire initial weld is desired.
While friction plug welding might be a preferred method of repairing defects or strengthening initial welds, there are some applications where heretofore it has been extremely difficult to use friction plug welding. The main cause is due to the logistics of setting up the equipment and/or support tooling to perform friction plug welding, and the geometry of the workpiece to be welded. The following are incorporated herein by reference: U.S. Pat. Nos. 3,853,258, 3,495,321, 3,234,643, 4,087,038, 3,973,715, 3,848,389, 5,460,317; British Patent Specification No. 575,556; SU Patent No. 660,801; German Patent No. 447,084, “New Process to Cut Underwater Repair Costs”, TWI Connect, No.29, January 1992; “Innovator's Notebook”, Eureka Transfer Technology, October 1991, p. 13; “Repairing Welds With Friction-Bonded Plugs”, NASA Tech. Briefs, September 1996, p. 95; “Repairing Welds With Friction-Bonded Plugs”, Technical Support Package, NASA Tech. Briefs, MFS-30102 (copy enclosed with the provisional patent application); “2195 Aluminum-Copper-Lithium Friction Plug Welding Development”, AeroMat '97 Abstract; “Welding, Brazing and Soldering”, Friction welding section: “Joint Design”, “Conical Joints”, Metals Handbook: Ninth Edition, Vol. 6, p. 726.
BRIEF SUMMARY OF THE INVENTION
The present invention solves the problems confronted in the art in a simple and straightforward manner. What is provided is a method of friction plug welding an article, comprising: making a hole in the article; inserting a plug into the hole; and pulling on the plug while spinning the plug relative to the article. Preferably the plug is pulled also after the spinning stops, with a load the same as or different from the load while spinning. The plug and the article can be made of the same material or of different materials. The mechanical properties of the weld of the present invention usually exceed those of the initial weld which it is repairing (when used to repair welds). The article can be equipment intended for use in extremely high temperatures and extremely low (down to −423 degrees F., for example). Preferably, the hole is tapered and the plug is tapered, causing a welded interface through the thickness of the plate, and which consists of such a geometry to create a force opposing the axial load induced by the weld system. In one condition that has been tested, the taper angle of the hole and the taper angle of the plug are equal and of the same orientation, causing near simultaneous contact over a large portion of the hole's surface and plug. This profile generally causes near equal heating time over the majority of the weldment's surface but causes a relatively large amount of cold friction when the plug and the article (workpiece) being welded initially contact. This relatively large frictional force must be overcome with high amounts of spindle torque to maintain rotation. Simultaneous heating of a large weld interface requires large amounts of power, however after the typical duration of less than one second has passed, this power requirement is rapidly reduced due to the development of a plasticized (heated to the point of having fluid like or viscous properties) layer at the weld interface. In another condition that has been tested, the tapers are of the same orientation but of slightly different angles. When this geometrical relationship between the plug and hole and/or the surrounding area exists, the surface areas that initially make contact are relatively small, and plasticization of this area of material requires less total energy. Plasticized material of this area is extruded, or moved from its original location due to the forces involved in performing the weld process, and causes an apparent lubricating affect on the remainder of the weld joint which is heated as the welding process continues.
Significantly less rotational power, primarily torque, is required to perform a weld with the aforementioned geometrical properties, and sound weldments can still be produced.
The present invention also includes the apparatus for carrying out the method of the present invention, as well as the article produced by the method of the present invention. The present invention relates to friction plug welding of aluminum alloys and to a new method of friction plug welding which we call friction plug pull welding.
The plug of the present invention could have a bore into which one could insert cooling fluid.


REFERENCES:
patent: 3234643 (1966-02-01), Hollander
patent: 3495321 (1970-02-01), Shaff et al.
patent: 3848389 (1974-11-01), Gapp et al.
patent: 3853258 (1974-12-01), Louw et al.
patent: 3973715 (1976-08-01), Rust
patent: 4059214 (1977-11-01), Weissmann
patent: 4087038 (1978-05-01), Yagi
patent: 5460317 (1995-10-01), Thomas et al.
patent: 5469617 (1995-11-01), Thomas et al.
patent: 5529333 (1996-06-01), Rizzi et al.
patent: 5718366 (1998-02-01), Colligan
patent: 5971252 (1999-10-01), Rosen et al.
patent: 5975406 (1999-11-01), Mahoney et al.
patent: 447084 (1929-05-01), None
patent: 575566 (1946-02-01), None
patent: 2306365 (1997-07-01), None
patent: 660801 (1979-05-01), None
“New Process to Cut Underwater Repair Costs”, TWI Connect, No. 29, Jan. 1992.
“Innovator's Notebook”, Eureka Transfer Technology, Oct. 1991, p. 13.
“Repairing Welds With Friction-Bonded Plugs”, NASA Tech. Briefs, Sep. 1996, p. 95.
“Repairing Welds With Friction-Bonded Plugs”, Technical Support Package, NASA Tech. Briefs, MFS-30102.
“2195 Aluminum-Copper-Lithium Friction Plug Welding Development,” AeroMat '97 Abstract.
“Welding, Brazing and Soldering”, Friction welding section: “Joint Design”, “Conical Joints”, Metals Handbook: Ninth Edition, vol. 6, pp. 719-

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