A one piece reusable fastener capable of joining materials together from one side (blind backside) comprises a screw driven pin ending in a wedge-shaped expander cone. The cone cooperates within a slotted collar end which has a number of tangs on a cylindrical body. The fastener is set by inserting it through aligned holes in the workpieces to be joined. Turning the pin in one direction draws the cone into the collar, deforming the tangs radially outward to mate with tapered back-tapered hold in the workpiece, thus fastening the two pieces together. Reversing the direction of the pin withdraws the cone from the collar, and allows the tangs to resume their contracted configuration without withdrawing the fastener from the insertion hole. The fastener is capable of joining materials together from only one side with substantial strength in tension and shear over many resue attachment cycles, with no special operations on the main assembly parts other than the tapering of the back end of the insertion hole

Peterson, S. A.

English

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NASA CASE N0. M5r 	
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NOTICE
The invention disclosed in this document resulted from
research in aeronautical and space activities performed under
programs of the National Aeronautics and Space Administration.
The invention is owned by NASA and is, therefore, available for
licensing in accordance with the NASA Patent Licensing
Regulation (14 Code of Federal Regulations 1245.2).
To encourage commercial utilization of NASA-owned inventions,
it is NASA policy to grant licenses to commercial concerns.
r
Although NASA encourages nonexclusive licensing to promote
competition and achieve the widest possible utilization, NASA
will consider the granting of a limited exclusive license,
pursuant to the NASA Patent Licensing Regulations, when such a
license will provide the necessary incentive to the licensee to
achieve early practical application of the invention.
7
Address inquiries and all applications for license for this
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Code AL3, Kouston, TX 77058. Approved NASA forms for
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IQ^ 	 J S C(NASA-Ca se
-MSC-18742- 1) TEUSABL.E CAPT:IVi
BLIND FASTENER Patent A Fplicat, on (NASA)
	
N82-26673
14 p HC A02/XF A01
	 NASA 131
Unclas
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AWARDS ABSTRACT	 NASA Case's No, MSC-18742- I
REUSABLE CAPTIVE BLIND FASTENER
The instant invention is directed to a one-piece reusable fastener capable:
of joining materials together from one side (blind backside).
The fastener comprises a screw driven pin E ending in a wedge-shaped
expander cone 31. Cone 31 cooperates within a slotted collar and 21: com-
prising a plurality of tangs 22 on cylindrical fastener body D. The fas-
tener is sett by inserting it through aligned holes in workpi,eces D and C
to be joined. Turning pin E in one direction draws cone~ 31 into collar 21
deforming tangs 22 radially outward to mate with baok-tapered hold 12 in
workpiece C, thus fastan,ing workpieces 8 and C together. Reversing the
direction of pin E withdraws cone 31 from collar 21, allowing tangs 22
to resume their contracted configuration upon withdrawing the fastener
from the insertion hole.
The novelty of the invention appears to lie in its particular two element
	 i
captive configuration and its ability to join materials together from only
one side with substantial strength in tension and shear over many reuse
Attachment cycles, and with no special operations on tho main assembly
parts other than the tapering of the back end of the insertion hole. i
i:.
Inventor:
	
Scott A. Peterson
Employer:	 Rockwell International
Initial Evaluator:	 David S. Grissom
S e r iceJ No	 Oq 3, y I `1
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REUSABLE CAPTIVE BLIND FASTENER
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Description
Origin of the Invention
The invention described herein was made in performance
5	 of work under a NASA contract and is subject to the pro-
visions of the National Aeronautics and Space Act of 1958,
Public Law 568 (72 Stat. 435, U.S.C. 2457).
Technical Field
This invention relates to blind fasteners and consists
10	 particularly of a reusable, one-piece fastener which re-'
mains united with a removable work piece and which requires
no special operations on the main assembly parts other than
beveling of the back or remote ends of the insertion holes.
Background of the	 Invention
15 There are many examples	 in	 the	 prior art of	 devices
utilizing
	
bolts	 or	 rivets with	 retracting wedges combined
with expanding
	
sheaths	 or the like	 to	 provide blind	 fas-
tenings.	 However, the	 prior art does not disclose	 a	 uni-
tary
	 or	 one-piece	 fastener which	 is	 self- retained	 in
20 a detachable work	 piece	 and which	 can	 be repeatedly
removed with
	
the	 latter work
	
piece
	
and reinstalled without
damaging any of the	 parts.
Examples	 of	 typical,	 somewhat	 similar, prior	 art,
blind	 fasteners	 are	 disclosed	 in	 the	 following United
25 States	 patents:
Jeal	 et	 al,	 No.	 3,878,760,	 discloses a bolt threaded
into	 a	 headed	 body	 and	 set	 by	 utilizing.a remote head on
the bolt to permanently	 swage a	 separate sleeve upwardly
about an	 expansion cone	 on	 the	 body	 shank and	 portions
30 of the	 bolt	 18	 deformed	 into	 slots	 in	 the body	 head.
Leonardo	 et	 al,	 No.	 3,922,947,	 has	 a separate,
segmented collar	 18 which	 is	 permanently expanded by
s
	
i
I
	
f
5
10
15
20
25
30
35
—2-
upward screwing of bolt 10.
Fischer, No. 3,958,488 discloses gripping sleeve
elements 2, 12, and 12a, non-releasably expanded within
the work piece.
Wenger, No. 3,812,756, uses a cone on the remote end
of a bolt to non-releasably expand an 0-ring within the
work piece.
Summary of the Invention
An object of the present invention is to provide a
reusable blind fastener which may remain captive on the
removable work piece only.
Another object is to provide a unitary or one-piece
blind fastener which may be secured in operating assembly
with min-imal modification of the work pieces.
Still another object is to provide a novel blind
fastener with improved load carrying capabilities in both
shear and tension.
In accordance with the invention, the novel, one-
piece, reusable, captive fastener consists of. a body with
an outer end head and a hollow, internally-threaded, tu-
bular shank.
	
At its remote or distal end, an unthreaded
portion of the shank is provided with axially projecting
tabs, preferably integral with the main portion of the
shank and resiliently carried thereby. The outer surface
of the body, intermediately, is provided with an annular
lip which is flaired to securely underly a chamfer or
recess in the removable work piece so that the fastener
remains captive in the latter even when freed from the
fixed work piece. An expander pin is internally threaded
in and through the body and has a wrenching socket in its
outer end and an expander cone at its remote end which
may be actuated, upon rotation of the pin, to expand the
body tangs against the beveled, remote corner of the wall
of the accommodating bore in the fixed work piece to
effect secure fastening together of the work pieces. The
outer work piece with the fastener unit captive therewith
t
3.
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-3
may be removed by reverse rotation of the pin to cause
the expansion cane to withdraw from the body tangs which
then relax to permit withdrawal of the fastener unit.
Brief Description of the Drawings
5	 In the accompanying drawings,
Fig. 1 is a longitudinal center section through the
novel fastener operatively assembled with work pieces.
Fig. 2 is a similar section showing the body tangs
relaxed for insertion and withdrawal of the fastener.
io	 Fig. 3 is a partial longitudinal center section
through the inner or remote portion of the body with the
expansion tabs relaxed, and
Fig. 4 is an enlarged, partial,.cross section taken
on the corresponding section line of Fig. 3.
15	 Detail Description-of the Ora wings
Fig. 1 shows the novel fastener unit, generally
designated A, operatively assembled with outer removable
and inner fixed work pieces B and C. Work piece B has
a bore 10 with a remote corner chamfer 11 and fixed work
20	 piece C has a somewhat smaller bore 10a and a larger
remote corner chamfer or diverging countersink 12. Both
chamfers can be formed by suitable tools inserted through
bores 10 and 10a, if necessary.
The fastener unit A comprises a body D with an outer
25	 head 13 overlying removable work piece B, and a hollow
shank including an outer portion 14 with an intern %al
thread 15, and a reduced skirt portion 16. The shank
portion 14 exteriorly terminates in a shoulder 17
between shank portions 14 and 16.	 The shoulder is partly
so	 severed axially, as at 19 (Fig.3), for flairing, as at
17a in Figs. 1 and 2, as will be explained. 	 Portions 16
of the body shank beyond threading 15, is reduced both
internally and externally.
The collar-like inner extremity 21 of the body shank
35	 is slightly thicker than adjacent part 16 and consists of
1-4-
a plurality of individual tangs 22 formed from the body
material by axial cuts 23 and small radial holes 24 at the
ends of the slots. The body, preferably, is formed of metal
which is tempered at its lower extremity to provide spring
s	 metal quality in the small sections connecting tangs 22 and
the adjacent shank part 16 whereby the tangs will be norm-
ally resiliently biased to their relaxed positions, as in
Figs. 2 and 3. At the upper ends, of tangs 22, portion 21
is provided with internal annular recessing 25 which co-
lo	 operates with the spring resilience of the tangs in re-
laxing of the latter when the fastner is to be released.
Radial bores 24 provide stress relief in the hinging por-
tion of the tangs.
Broadly, the hinging of tangs 22 is not, necessarily,
is	 resilient, but may be merely flexible, and body A may be
made of other materials, as plastics. 	 It is contemplated
however, that the tangs may be expanded and contracted
many times,
Received in body A is the expansion pin E with its
20,	 outer threaded portion 27 meshing with body threads 15. A
wrench socket 28 providers for rotating the pin to propel
the same longitudinally within body A.
?, reduced portion 29 of the pin is adjacent threaded
portion 27 thereof and forms the shoulder 30 therewith.
25	 At the extreme inner end of the pin is the expander cone
31.
Operation
In order to install the fastener, work pieces B and
C are first bored and bevelled, as at 10, 10a, 11, and 12.
30	 Fastener unit A with body D and expander pin E assembled
is then installed in outer work piece bore 10 and lip
17a flaired with a suitable tool to snugly grip edge
bevel 11 to hold the fastener unit captive. Other means,
such as embedding the flair 17a in a differently located
35	 recess in bore 10, may be used to secure the fastener in
t:.
-5-
removable work piece B.
The joined fastener A and movable work piece B are
then assembled with fixed work piece C with the work
pieces abutting and fastener body D snugly fitting bores
	
5	 10 and 10a.	 Pin E will be screwed into body D of the
fastener merely far enough to cause the inner extremity
of the cone 31 to approach or contact the free extremities
of tangs 22 (fig. 2).
With the tangs resiliently biased, they will converge
	
to	 slightly in the relaxed position, being limited by
engagement with reduced pin portion 29 just above cone 31.
In order to secure the assembly, piti E is rotated to
cause the cone to enter the tanged collar 21 and expand
tangs into firm engagement into undercut 12. To remove
	
is	 outer work piece 6 and captive fastener A, pin E is
rotated in the opposite direction, propelling cone 31 out
of collar 21, relaxing the tangs to permit withdrawal of
the fastener unit from bore 10a without damaging or other-
wise affecting any of the parts, either of the work
	
20	 pieces or the fastener.
The fastener parts will remain threadedly assembled
in a one-piece assembly and this assembly will remain
captive in removable work piece Q until disassembled, as
by straightening of flaired lip 17a.
	
25	 The invention may be modified in various respects
as will occur to those skilled in the art and the
exclusive use of all modifications as come within the
scope of the appended claims is contemplated.
^P
ABSTRACT OF THE DISCLOSURE
A ona-piece blind fastener self-retained in a
detachable work piece B and capable of repeated removals
from and reinstalations in the fixed work piece C.
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Reusable captive blind fastener

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