Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to a blind fastener
for joinin~ together a plurality of workpieces.
One of the main difficulties in blind fasteners
has been in providing a construc:tion which would assure
uniform preload values for a varie-ty of grips or material
thicknesses.
Illustrative of prior attempts are those disclosed
in Schmitt U.S. Patent No. 3,702,088; Gapp U.S. Patent No.
3,148,578; Reynolds U.S. Patent No. 3,288,016; and Binns
U.S. Patent No. 3,880,042.
The present invention resides in a blind fastener
for joining together a plurality of workpeices over a wide
range of grips, the fastener having a hollow tubular sleeve
- provided with a preformed head at one end an open tubular
extension at the other end, and a pin including a shank
disposed within the tubular sleeve having pull means formed
thereon extending beyond the preformed head on the sleeve
and having a blind head forming portion extending beyond the
other end of the sleeve. The blind head forming portion
includes a plurality of spaced circumferentially extendin~
- ribs forming grooves therebetween constructed to engage and
expand the other end of the sleeve to form the blind head.
Selected ones of the ribs are adapted to fold back successi~ely
as they are moved through a plane defined by the rearward
surface of the workpiece. At least one of the plurality of
ribs remains in an unfolded condition proximate to the rear-
ward surface after setting of the fastener and when the
fastener is applied to workpieces of different grips within
the wide range.
In one embodiment of the invention, the ribs are
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adapted to fold bac~ successively in engagement wi-th the
inner wall of the o-ther end as the fastener is se-t for
different grips, -the grooves having a roo-t diameter less
than the diameter of the pin shank and the last following
rib of the head forming portion is of the greatest strength
and the first leading rib is of a streng-th more resistant
to deflection than the remaining ribs intermediate the last
following rib and the first leading rib.
Depending upon the grip or material thickness with
which the fastener is used, the ribs will progre~sively engage
the end of the sleeve, form the blind head, and collapse or
progressively fold back as the head is formed. At the end
of the stroke, depending on the grip, pull pressure builds
up to break the pin at the breakneck to complete setting of
the fastener.
In the embodiment illustrated the pin and sleeve
are preferably locked together as disclosed in the prior
Reynolds U.S. Patent. Other known ways of providing the
interlock may be used.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevational view of a fastener
with parts sectioned and parts in elevation, embodying features
of the present invention and in assembled relation with a pair
of workpieces to be fastened together at nominal grip and with
the fastener depicted prior to being set;
Figure 2 is a view similar to Figure 1 depicting the
fastener at an early stage of its being set; ~.
Figure 3 is a view similar to Figure 2 at a further
stage;
Figure 4 is a view similar to Figures 2 and 3 at the
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final set stage, with the pin tail broken off and with the
pin and sleeve interlocked; and
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Fi~lrc 5 is a view similar to Ii`ig-lre ~ with thc Iastc?ner
finally set in worlipieces of maximum thickness or maxirn~lm grip.
DESCI~IPTION OF TIIE PI~E:F~RRI~D E:MBODIM13NT
AND BEST MODE: OF OPER~TION
. ._ .
Rererring to Figures 1 to 4, a fastener 10 is sho~rn in
14
assembled relationship witll a pair of worlipieces 12 and :1~ to be joined
together. The fastener 10 comprises a tubular sleeve 16 with a central
bore 18 and a pin 20 extending theretlirough.
The sleeve 16 has a ~rusto-c-onlcally shaped head 22 at
its forward or outside end ~vhich mates ~vith a co~lntersllnl; bore 24 in the
outer ~ace of the worlipiece 1~. The sleeve 16 has a cylindrical body
portion 26 ~vhich e~;tends rearwardl~ through and substantially beyond
opening 2 in rear or inr.er workpiece 12~.
The bore 18 terminates adiacent the head 22 in an annular
shoulder 30 ~Yhich provides material for interlocl;ing the pin 20 and the
sleeve 16 and also provides a positive stop for lim;ting the movement of
the pin 20 relative to the sleeve 16 as disclosed in the aforementioned -
~Reynolds patent. `
The pin 20 DS assembled to the sleeve has a head end
generaIly indicated at 32, a shanlc portion 3~, a loclc groove 3~iJ a breal;-
necli groove 38, and a pull portion ~0 formed of annular pull grooves in
the l~sual ~vay.
The present inventjon lics in the construct jon of tlle
he.lcl c:lld 32 of thc pin 20, its arrangcmellt witl- rcspect to the inllCI` entl
of thc slccvc ancl its functlon in fo~ming tllc llljn(l heacl for the acccmmc)clation
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of different ~rips. ~ 7
The head end portion 32 comprises a plurality of
annular ribs 42, 43 44 and 45 and terminating in an end rib 46.
Such ribs are formed by spaced annular grooves 4~ the root
diameters of which are less than the diameter of the shank
portion 34~ The ribs are also preferably shaped to have a
pyramidal cross-sectional configuration tapering inwardly to
have a base portion of greatest strength. This permits the
controlled and progressive bending of the ribs as the fastener
is set.
Although it is preferable to form the ribs by way
of spaced annular grooves, an alternate way would be the
formation of such ribs as a spiral thread. By controlling
the depth, or root diameters, of the grooves 48 and/or the
transverse width or configurations of the grooves, the cross-
` sectional configuration of the ribs may be likewise varied to
vary the resistance to deflection or bending of such ribs.
Thus, sleeve expansion or head formation may be varied for
a desired design as well as load resistance at any portion
of the installation cycle.
2C The rib 42 is stronger than ribs 43, 44 and 45
because the diameter of shank 34 is greater than the root
diameter of adjacent groove 48. In the embodiment illustrated
ribs 43, 44 and 45 have uniform resistance to bending. But
variation in such bending resistance could be accomplished
by varying the root diameters of grooves 48 The end rib 46
preferably has the greatest width dimension so that it is
the strongest and not bendable at the end of the setting
stroke.
Referring to Figure 2, the blind head has been
formed and the first rib 42 collapsed or folded back. In
Figure 3, at a further step in the setting cycle, the pin 10
has moved further into the sleeve and ribs 42 and 43 folded
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back or collapsed. In Figure 4~ the pin 10 has been moved
to its complete set position, the interlock 30 has occurred,
and the pin broken at the break-neck 38. For this grip,
ribs 42 and 43 have folded back and rib 44 is beginning to
fold back.
Referring to Figure 5, workpieces 13 and 15,
corresponding to members 12 and :L4, are thicker and may be
considered as illustrative of ma~imum grip. Thus, when
finally set, ribs 42, 43, 44 and 45 have all collapsed
back~7ardly.
While it will be apparent that the preferred
embodiments of the invention disclosed are well calculated
to fulfill the objects above stated, it will be appreciated
that the invention is sUsceptable to modification, variation
and change without departing from the proper scope or fair
meaning of the subjoined claims.
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