Note: Descriptions are shown in the official language in which they were submitted.
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SUM~RY BACKGROUND OF THE INVENTION
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The present invention relates to tools for setting
fasteners having pin members wi;th pull grooves and more partic~l-
larly to tools havlng a plurality of jaws for gripping the pull
grooves. ~ ~ .
; In the setting of multi-pieced fasteners generally of ~ :
types such as those shown in the ~.S. Patent Nos. 2,527,30~ -
and 2/531,048 issued to L. C. Huck on October 24, 195~ and
Novemher 21, 1950, respectively, it:has been the practice to
utilize a tool having a plurality of generally independently
movable chuck jaws. The latter;are generally shown in the above
- noted patents to L. C~ Huck and the details of the same are
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exemplified in the U.S. Patent;No. 3,107~,806 issued october 22r
1963 to G. J. Van Hecke et~al.:
With such jaw structures it is possible under certain
conditions of pin insertion~to move the jaws out o~ axial
alignment. When this occurs and the tool is actuated, the pin
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is gripped by less than the full complement of jaws; this can
lead to stripping of the jaw teeth, stripping of the pull
gxooves and/or ultimate failure of one or more jaws.
In addition such jaw structures are normally held
closed by a spring biased jaw follower assembly. Thus, i~
order to insert the pin into the jaw~ the spring bias l~ad must
be overcome as the jaws are moved axially rearwardly and radiall~
outwardly. In some assembly operations such insertion loads
can be undesirably high.
For example, the insertion load magnitude appears
to be aggravated by fasteners in which the grooves to be
gripped on the pin are relatively deep. Such a fastener structure
is shown and described in U.S. Patent No. 4,208 r 9~3 issued
June 24, 1980. With such fasteners it is possible for one of
the jaws to be permanently moved from its proper position
requiring the tool to be disassembled and the jaw properly
positioned again. In addition, occasionally with the latter
type fastener, pin break may occur across more than one groove
resulting in relatively small sized debris being carried into
the tool. With conventional tool structure, the large number
of reiatively independently movable parts provides an environment
in which the debris may lodge and eventually jam the tool
or seriously impair its operation. As shown in the above
noted patent the fastener includes a pin member
having a plurality of grooves and associated crests; these
grooves and crests are substantially identical annular combination
locking and breakneck grooves defined by cooperating slde walls
which converge into a selected
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concave radius portion. This concave radius portion is of a
magnitude selected to provide a predetermined st~ess concentration
to facilitate fracture at a selected one of the grooves proximate
the outer end of an associated collar.
According to the present inventlon there is
provided an apparatus Eor setting a astener which has a
pin member with a head and shank and a plurality o~ yrooves ~herein
and a tubular member adapted to be located over the shank o~ the
pin member and cooperating with the pin member to secure a
plurality of workpieces together upon the application of a
relatively axial force between the pin member and the tube
member. The apparatus includes a generally tubular shaped
anvil member with an~ aperture extending through a forward
portion thereof for applying a relatively axial force between
the tubular member and the pin member. A generally tubular
collet member is slidahly located within the anvil member
and has an axial bore terminating at its forward end
in a tapered bore portion. A plurality of ~huck jaws define
a frusto conical outer surface adapted to generally matably fit
within the tapered bore portion of the collet and each having
an inner surface with a plurality of teeth thereon adapted to
grip at least some of the grooves of the pin member. ~ tubular
sleeve member is slidably disposed in the axial bore, the chuck
jaws being secured to a forward end of the tubular sleeve. The
tubular sleeve and the chuck jaws are free to move axially within
the axial bore from a first position in which the jaws are engage-
able with the tapered bore portion and are radially closed thereby
and a second position in which the jaws are in a radially open
condition, the jaws as secured to the tubular sleeve normally
being held in the open condition.
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According to a specific embodiment of the invention,
the jaws which are conventionally constructed of haxdened steel,
are secured to the sleeve which by an elastomeric structure
such that axial misalignment is substantially precluded.
At the same time the jaws are held in a preselected open posltion
whereby insertion loads are minimi~ed. Since the number o pa~ts
is substantially reduced the likelihood of the tool jaming ~om
debris is minimi~ed.
Thus, the tool and the noted fastener co~perate to
provide a novel fastening system. It should be noted, however,
that the tool can be utilized with fasteners of a different
construction.
other objects, features and advantages of the present
invention will become apparent from the subsequent description
andthe appended claims, taken in conjunction with the accompanying
drawing, in which:
Figure 1 is a longitudinal view with some parts shown
in section of a tool and fastener of the present invention prior
to appiication of the tool to the fastener;
Figure 2 is a similar longitudinal view showing the
tool applied to the fastener but prior to actuation-of the tool;
Figure 3 is a similar longitudinal ~iew showing the
tool and fastenex with the tool having been actuated and in its
second pull stroke and with fastener having been substantially
set; and
Figure 4 is a sectional view of the tool of Figure 1
taken generally along the lines 4-4 of Pigure~l.
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~ ooking now to the drawings, a pull gun assembly is
~enerally indic~ted by the numer~l 10 and comprises a pull gun
member 12 (partially shown in phantom lines) which is operable
with a nose assembly 14 fox se~tin~ a fastener 16. The ~stener
16, includes a pin member 18 ana a collar 20~ adapted to be
swaged thereon, with the pin 18 being disposed in aligned bores
in a pair of workpieces 22 and ~4. The pull gun member 12 can be
of a conventional type capable of applying a relative axial force
such as that described in U.S.patent to L. C~ Huck, No. 2,13Z,112.
The nose assembly 14 comprises a generally tubular
outer anvil member 26 having an axial bore 27 and having radially
extending ears or lugs 28 proximate one end fox lockiny engagement
with the receivin~ end of the casing of the ~un member 12 by
means known to the art. In this regard the ears or lugs 28
could be provided by a separate ring and qroove combination.
The opposite end of the outer anvil membex 26 is
substantially closed by an anv~l portion 30 having a swaging bore
32 located therein. Note that in some constructions a separate
anvil portion could be util~zed ~as shown in the noted copending
patent application). The swaging bore 32 can have a variety of
shapes selected to facilitate swaging.
Slidably a; sposed within the outer anvil membex 26
is generally tubulax collet member 34 which has an axial bore 36
which is internally threaded at its rearward portion 38. This
rearward portion 38 is threadably engaged with a threaded portion
40 of a piston rod (partially shown~ of the pull gun memher 12.
~he forward end of the collet member 34 has an axially outwardly
radially inwardly tapered ~ore 4~ which terminates at its enlarged
end in an increased diameter bore portion 44.
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A unitized jaw assembly and follower 46 i5 slidably
disposed within the collet member 34 and comprises a plurality
of jaw members 48 secured at their rearward ends to the leading
surface of a generally tubular elastomeric sleeve member 50.
The outer surfaces of the jaw members 48 define a frusto
conically inclined surface which is matable within the tapered
bore 42.
In one form of the invention the elastomeric member
50 can be of a flexible urethane construction. The jaw members
48 (which in one form are three in number) can be bonded to the
sleeve member 50 as a separate step or can be bonded simultaneously
with the forming of the elastomeric member 50 where a urethane
construction is used. The rearward ends of the jaw members 48
can be notched, grooYes or serrated to increase the surface
area and to thereby enhance the bond with the sleeve member SOO
Thus the jaw members 48 are flexibly secured to the resilient
sleeve member 50 and as secured can resiliently move radially.
Note that since the member 50 is elastomeric the jaw members 48
can, to a degree, move resiliently axially.
The jaw members 48 have pluralities of teeth 52 for
gripping the grooves of the pin member 18. Note that the teeth
5~ are of a shape which are similar to and generally complement
the grooves of pin member 18. As secured to the sleeve member 50
the teeth 52 of each of the jaw members 48 are located and held
in axial alignment with those of the other jaw members 48. Since
relative axial movement between jaw members 48 is inhibited by
the sleeve member 50, axial misalignment between teeth 52 is
substantially precluded whereby proper engagement of the grooves
of the pin 18 by the teeth 52 of all of the jaw members 48 is
3~ substantially assured.
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It is desirable that the ~aw members 48 not be held
closed under a high preload. To this end, with the present inven-
tion, the jaw members 48 can be located via the flexible connec-
tion with the sleeve member 50 such that in their ~ela~ed, non
actuated condition the ~aw members are generally opened, i.e
radially~ ~paced from each other, whereby the crests of the jaw
teeth 52 define an insertion diameter D. The diameter D is
slightly less than the crest diameter Dl on the pin member 18
whereby a preselected minimum interference is provided. The
màgnitude of this interference is selected to provide a minimum
insertion force when the pull gun 12 is applied to the pin 18
and at the same time to assure sufficient interference during
initial gripping. The initial gripping of the pin member 18
occurs when the pull gun assembly 10 is actuated to move the collet
member 34 rearwardly relatively to the outer anvil 26 at which
time the tapered bore 42 engages the frusto conical surface of
the jaw members 48. The initial gripping or interference must
be sufficient to;hold the jaw and follower assembly 46 to the
grooves of the pin 18 so that the jaws 48 will not slip off the
pin 18. Further relative rearward movement of the collet member
34 will cause the jaw members 48 to move forwardly (relatively)
into the tapered bore 42 causing the jaw members 48 to attain
their fully closed position whereby gripping of the pin 18 is
complete. Further movement of the collet 34 and the jaw and
follower assembly 46 relative to the outer anvil 26 will result
in application of the desired relative axial force between pin
18 and coltar 20 and in setting of the fastener lS; if the
stroke of the pull gun 12 is insufficient to completely set the
fastener 16, its continued actuation will result in a second
cycle, i.e. reciprocation of collet 34 and jaw and followerassembly
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46 whereby the pin member 18 will be gripped closer to tha
collar 20. tsee Figure 3). Upon setting of the fastener 16
the pin member 18 will be severed at one of the grooves near the
end of the collar 20. The severed portion o the pin m~mber
18 will pass through the pull gun 12 via sleeve member 50 for
ejection out the rear of the pull gun 12.
In order to provide minimum insertion loads while still
providing sufficient interference for initial gripping it is
desirable to have the crest diameter D on the jaws 48 such that
at initial gripping the teeth 52 will be located at approximately
one half the depth of the grooves of the pin member 18, i.e. the-
mean diameter between the grooves and the associated crests
on the pin member 18 (see Figure 2).
x Note that in the construction of Figures 1-3, the jaw
and follower assembly 46 is free to float, i.e. move axially,
within the collet 34 between the threaded portion 40 of the piston
rod and the tapered bore 42. This permits some degree of
radially outward movement of the jaw members 48 whereby the pin
member 18 can be inserted through the opening tdlameter D)
with a ratcheting type action. It is preferred, however, that
the amount of axial movement of the ~aw and follower assembly 46
be limited to no more than around one pitch, P, of the grooves
of pin member 18. This limitation on the axial float ls provided
to minimize the reduction in ~rip capability of the nose assembly
14, i.e. the minimum }ength of pin member 18 required to per~it
gripping by the jaw members 48. The axial float can be minimized
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where the flexibility of the sleeve`member 50 is sufficient to
permit the necessary mo~ement of the ~aw members 48.
The sleeve member 50 being r`esilient does permit
deflection of the jaw members 48 and also provides a shook
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absorbing function at pin break. Since the sleeve mem6er 50
extends generally for the length of the collet bore 36 that portion
of the pin member 18 severed at pin break and resultant debris
carried by the broken pin portion or otherwise located within
the sleeve member 50 can be expelled thereby reduaing the llkeli-
hood of jamming the nose assembly 14.
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 susceptible to modification, variation and change without
departing from the:proper scope or fair meaning of the invention.
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