A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus

Carter, Robert W.

Lawless, Kirby G.

NASA Technical Reports Server

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(12) United States Patent
Carter et al.
(54) GIMBALED-SHOULDER FRICTION STIR
WELDING TOOL
(75) Inventors: Robert W. Carter, Huntsville, AL (US);
Kirby G. Lawless, Huntsville, AL (US)
(73) Assignee: The United States of America as
represented by the Administrator of
the National Aeronautics and Space
Administration, Washington, DC (US)
(*) Notice: Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 262 days.
(21) Appl. No.: 11/543,287
(22) Filed:	 Sep. 29, 2006
(51) Int. Cl.
B23K 20112	 (2006.01)
B23K 37100	 (2006.01)
(52) U.S. Cl . ......................................... 228/2.1; 228/2.3
(58) Field of Classification Search .................. 228/2.1,
228/2.3
See application file for complete search history.
(56)	 References Cited
U.S. PATENT DOCUMENTS
2,625,018 A *	 1/1953 Dunn ........................ 464/66.1
5,697,544 A	 12/1997 Wykes
5,718,366 A *	 2/1998 Colligan .................. 228/112.1
5,893,507 A	 4/1999 Ding et al.
6,050,475 A	 4/2000 Kinton et al.
(1o) Patent No.:	 US 7,686,202 B1
(45) Date of Patent: 	 Mar. 30, 2010
6,199,745 131 * 3/2001 Campbell et al. 	 ........	 228/112.1
6,227,430 131 5/2001 Rosen et al.
6,237,835 131 5/2001 Litwinski et al.
6,484,924 131 11/2002 Forrest
6,543,671 132 4/2003 Flatten et al.
6,557,746 132 5/2003 Ezumi et al.
6,595,403 132 7/2003 Okamura et al.
6,669,075 132 12/2003 Colligan
6,715,665 132 4/2004 Hirano et al.
6,758,382 131 7/2004 Carter
RE39,019 E 3/2006 Tully et al.
2003/0028281 Al 2/2003 Adams et al.
2003/0201307 Al 10/2003 Waldron et al.
2004/0079787 Al 4/2004 Okamoto et al.
2005/0029330 Al 2/2005 Kohn
FOREIGN PATENT DOCUMENTS
JP	 2003181654 A * 7/2003
WO	 WO 2006081819 Al * 8/2006
* cited by examiner
Primary Examiner Jessica L. Ward
Assistant Examiner JackyYuen
(74) Attorney, Agent, or Firm James J. McGroary; Peter J.
Van Bergen
(57)	 ABSTRACT
A gimbaled-shoulder friction stir welding tool includes a pin
and first and second annular shoulders coupled to the pin. At
least one of the annular shoulders is coupled to the pin for
gimbaled motion with respect thereto as the tool is rotated by
a friction stir welding apparatus.
8 Claims, 2 Drawing Sheets
1---------- T
10A	
200
12
14 '^ 100
	
^	 '
^10
16	
22 	 300A
	
22A	 j
----	
16A
----
---------
 	 300I
I
I
------------
18	 ^^	 ^;	 - - - - 24A 3008
24 	 ^^	 I 	 ^'i	
1
	
20
'	 28
26''	 16B
https://ntrs.nasa.gov/search.jsp?R=20100015647 2019-08-30T09:27:49+00:00Z
10
21
12
U.S. Patent	 Mar. 30, 2010	 Sheet 1 of 2	 US 7,686,202 B1
FIG. 1
is	 zzn^
26"
200
f100
f10
300A
^ 16A
300
300B
^
20
:28
16B
FIG. 2
40
20
18
L6
300
FIG. 3
U.S. Patent	 Mar. 30, 2010	 Sheet 2 of 2	 US 7,686,202 B1
18
US 7,686,202 B1
1
GIMBALED-SHOULDER FRICTION STIR
WELDING TOOL
ORIGIN OF THE INVENTION
The invention was made by employees of the United States
Government and may be manufactured and used by or for the
Government for governmental purposes without the payment
of any royalties.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to friction stir welding tools. More
specifically, the invention is a friction stir welding tool having
at least one gimbaled shoulder contacting a workpiece.
2. Description of the Related Art
Many friction stir welding (FSW) apparatus utilize a weld-
ing tool that has two spaced-apart shoulders fixedly mounted
to a welding pin that is rotated about its axis by the FSW
apparatus. The two shoulders rotate with the pin and ride on
the respective front and back (or top and bottom) of the
workpiece being welded. If the thickness of the workpiece
varies as the welding tool is moved therealong, the leading
edge of one or both shoulders tend to dig into the workpiece
which causes excessive weld flashing to develop along the
weld.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to
provide a friction stir welding (FSW) tool that can adapt to
varying-thickness workpieces.
Another object of the present invention is to provide a FS W
tool that adjusts itself to handle welds of constant thickness,
tapering thickness and complex curvature joints.
Other objects and advantages of the present invention will
become more obvious hereinafter in the specification and
drawings.
In accordance with the present invention, a tool is provided
for use in friction stir welding. The tool includes a pin and first
and second annular shoulders coupled to the pin. The shoul-
ders are spaced apart from one another along the pin's longi-
tudinal axis. The pin is further adapted to be coupled to a
friction stir welding apparatus for rotation about its longitu-
dinal axis. At least one of the first and second annular shoul-
ders is coupled to the pin for gimbaled motion with respect
thereto.
BRIEF DESCRIPTION OF THE DRAWING(S)
Other objects, features and advantages of the present
invention will become apparent upon reference to the follow-
ing description of the preferred embodiments and to the draw-
ings, wherein corresponding reference characters indicate
corresponding parts throughout the several views of the draw-
ings and wherein:
FIG. 1 is a side view of a gimbaled-shoulder friction stir
welding tool in accordance with an embodiment of the
present invention;
FIG. 2 is a perspective view of the embodiment shown in
FIG. 1 illustrating the underside of the gimbaled-shoulder
tool;
FIG. 3 is a side view of a two gimbaled-shoulder tool in
accordance with another embodiment of the present inven-
tion.
2
DESCRIPTION OF THE PREFERRED
EMBODIMENT(S)
Referring now to the drawings, simultaneous reference
5 will be made to FIGS. 1 and 2 where a gimbaled-shoulder
friction stir welding (FSW) tool in accordance with an
embodiment of the present invention is shown and is refer-
enced generally by numeral 10. Tool 10 will be coupled to a
FSW apparatus, a portion of which is illustrated in phantom
io lines and is referenced by numeral 100. In general, FSW
apparatus 100 will cause tool 10 to rotate about its longitudi-
nal axis 10A as indicated by arrow 200. A variety of such
FSW apparatus are well known in the art. Accordingly, it is to
be understood that the particular type of FSW apparatus is not
15 a limitation of the present invention.
Typically, tool 10 has a base or support 12 that facilitates
the coupling of tool 10 to FSW apparatus 100. By way of
non-limiting example, support 12 can have threads 14 formed
thereon that thread into FSW apparatus 100. Of course, sup-
20 port 12 can be coupled to FSW apparatus 100 in other ways
without departing from the scope of the present invention.
Coupled to and extending from support 12 is a pin 16 such
that pin 16 will rotate about its axis 16A with support 12 when
FSW apparatus 100 is operated. Axis 16A is coincident with
25 the longitudinal axis 10A oftool 10. Inthe illustrated embodi-
ment, pin 16 terminates at its distal end 16B with a bulbous or
ball shape from which two indexing pins 18 and 20 extend
radially outward therefrom. More specifically, indexing pins
18 and 20 are oriented 90° away from each other in a plane
so perpendicular to axis 16A. The function of indexing pins 18
and 20 will be explained further below.
Tool 10 further includes two annular shoulders 22 and 24
separated from one another along pin 16. Upper shoulder 22
is fixedly coupled to support 12 and/or pin 16 for rotation
35 therewith about axis 16A. Upper shoulder 22 is disposed
annularly about pin 16. The lower surface 22A of upper
shoulder 22 will ride on the top surface 300A of a workpiece
300 (shown in phantom lines) to be welded as pin 16 rotates.
Opposing upper shoulder 22 is lower shoulder 24 also
4o disposed annularly about pin 16 with its upper surface 24A
riding along the bottom surface 300B of workpiece 300.
Rather than being fixedly coupled to pin 16, lower shoulder
24 is loosely coupled to pin 16 suchthatlower shoulder24 can
rotate with pin 16 while simultaneously experiencing gim-
45 baled motion relative to pin 16. To achieve this function in the
illustrated embodiment, lower shoulder 24 defines a socket 26
(FIG. 2) that engages the ball-shaped distal end 16B of pin 16
as indexing pins 18 and 20 engage correspondingly-posi-
tioned slotted notches 28 and 30 in lower shoulder 24. The
50 engagement of indexing pins 18 and 20 in respective slotted
notches 28 and 30 links lower shoulder 24 to pin 16 such that
it will rotate with pin 16. At the same time, the loose engage-
ment of indexing pins 18 and 20 in slotted notches 28 and 30
allows lower shoulder 24 to gimbal on distal end 16B of pin
55 16 when forces are applied to upper surface 24A.
In operation, as FSW apparatus 100 rotates support 12/pin
16, upper shoulder 22 and lower shoulder 24 rotate therewith
as indexing pins 18 and 20 engage notches 28 and 30, respec-
tively. If the thickness of workpiece 300 changes as FSW
6o apparatus 100 moves tool 10 therealong, the changing thick-
ness of workpiece 300 applies forces to upper surface 24A of
lower shoulder 24 with the applied forces causing lower
shoulder 24 to gimbal. For example, if workpiece 300 gets
thicker as tool 10 moves therealong, a downward force (i.e.,
65 where "downward" is relative to the illustrated orientation of
tool 10) will be applied to the leading edge of upper surface
24A causing it to pitch downward so that the leading edge
US 7,686,202 B1
3
does not dig into workpiece 300. Conversely, if workpiece
300 gets thinner as tool 10 moves therealong, a downward
force (i.e., where "downward" is relative to the illustrated
orientation of tool 10) will be applied to the trailing edge of
upper surface 24A causing it to pitch upward so that the
trailing edge does not dig into workpiece 300. In this way,
excessive weld flashing is eliminated.
The present invention is not limited to the specifics of the
illustrated embodiment. For example, the gimbaled motion
between lower shoulder 24 and pin 16 can be provided by a
number of other constructions without departing from the
scope of the present invention. Also, the tool of the present
invention could be constructed so that the upper shoulder
thereof was capable of gimbaled motion as opposed to the
lower shoulder as in the illustrated embodiment. Still further,
depending on the construction of the FS W apparatus to which
the tool is to be mounted, it is possible that the tool of the
present invention does not require a support (i.e., support 12).
That is, the tool of the present invention might only include
the pin and two annular shoulders.
The advantages of the present invention are numerous. The
gimbaled-shoulder friction stir welding tool automatically
adapts to workpiece variations without requiring any com-
plex control systems. Thus, the tool provides a simple and
inexpensive way to improve the quality of friction stir welds.
Although the invention has been described relative to a
specific embodiment thereof, there are numerous variations
and modifications that will be readily apparent to those
skilled in the art in light of the above teachings. For example,
as illustrated in FIG. 3, the tool of the present invention could
be constructed with two gimbaled shoulders. That is, upper
shoulder 22 could also be loosely coupled to pin 16 to rotate
therewith while simultaneously being capable of experienc-
ing gimbaled motion with respect thereto. By way of an
illustrative example, this can be achieved in the same way as
previously described for lower shoulder 24. Accordingly, pin
16 can include an intermediately-positioned bulbous or ball-
shaped region 16C that is engaged by a socket 36 defined in
upper shoulder 22. Indexing pins 38 and 40 extending radially
from region 16C are engaged in slotted notches formed in
upper shoulder 22 in a similar fashion to that previously
described for lower shoulder 24. Note that only one such
slotted notch (i.e., slotted notch 48) is visible in FIG. 3. It is
therefore to be understood that, within the scope of the
appended claims, the invention may be practiced other than as
specifically described.
What is claimed as new and desired to be secured by
Letters Patent of the United States is:
1. A tool for use in friction stir welding, comprising:
a support body adapted to be coupled to a friction stir
welding apparatus for rotation thereby;
a pin fixedly coupled to and extending from said support
body for rotation therewith;
first and second annular shoulders coupled to said pin and
spaced apart from one another, said first and second
annular shoulders adapted to be disposed on opposing
sides of a workpiece;
at least one of said first and second annular shoulders
defining a socket;
said pin including a bulbous portion thereof for engage-
ment in said socket; and
a plurality of indexing pins fixed to and extending radially
outward from said bulbous portion for loose engage-
ment with slotted notches formed in said at least one of
said first and second annular shoulders, wherein said at
least one of said first and second annular shoulders is
coupled to said pin for simultaneous rotation therewith
4
and gimbaled motion with respect thereto such that
changes in thickness of the workpiece changes forces
applied to said at least one of said first and second
annular shoulders to directly control relative orienta-
5	 tions between said first and second annular shoulders as
said pin rotates.
2. A tool as in claim 1 wherein each of said first and second
annular shoulders is coupled to said pin for rotation therewith.
3. A tool for use in friction stir welding, comprising:
10 a pin having a longitudinal axis, said pin being adapted to
be coupled to a friction stir welding apparatus for rota-
tion about said longitudinal axis;
first and second annular shoulders coupled to said pin and
spaced apart from one another, said first and second
annular shoulders adapted to be disposed on opposing
i5	 sides of a workpiece;
at least one of said first and second annular shoulders
defining a socket;
said pin including a portion thereof for engagement in said
socket; and
20 a plurality of indexing pins fixed to and extending radially
outward from said portion of said pin engaged in said
socket and perpendicular to said longitudinal axis for
loose engagement with slotted notches formed in said at
least one of said first and second annular shoulders,
25 wherein said at least one of said first and second annular
shoulders is coupled to said pin for simultaneous rota-
tion therewith and gimbaled motion with respect thereto
such that changes in thickness of the workplace changes
forces applied to said at least one of said first and second
30 annular shoulders to directly control relative orienta-
tions between said first and second annular shoulders as
said pin rotates.
4.A tool as in claim 3 wherein each of said first and second
annular shoulders is coupled to said pin for rotation therewith.
35	 5. A tool for use in friction stir welding, comprising:
a pin having a longitudinal axis, said pin being adapted to
be coupled to a friction stir welding apparatus for rota-
tion about said longitudinal axis, said pin having a distal
end that is at least partially spherical;
a first annular shoulder fixedly coupled to said pin for
40	 rotation therewith, said first annular shoulder opposing
and separated from said distal end of said pin;
a second annular shoulder forming a socket disposed about
said pin, said first and second annular shoulders adapted
to be disposed on opposing sides of a workpiece; and
45 a plurality of indexing pins fixed to and extending radially
outward from said distal end and perpendicular to said
longitudinal axis for loose engagement with slotted
notches formed in said second annular shoulder,
wherein said second annular shoulder is loosely coupled
50 to said distal end of said pin to simultaneously provide(i) rotation with said pin, and (ii) gimbaled motion rela-
tive to said distal end such that changes in thickness of
the workpiece changes forces applied to said second
annular shoulder to directly control orientation of said
second annular shoulder as said pin rotates.
55 6. A tool as in claim 1 wherein said plurality of indexing
pins comprises two indexing pins oriented with an angle of
90° therebetween.
7. A tool as in claim 3 wherein said plurality of indexing
pins comprises two indexing pins oriented with an angle of
60 90° therebetween.
8. A tool as in claim 5 wherein said plurality of indexing
pins comprises two indexing pins oriented with an angle of
90° therebetween.


Gimbaled-shoulder friction stir welding tool

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