Note: Descriptions are shown in the official language in which they were submitted.
32~ j
The invention rela-tes to a self-attaching fastener
and more particularly to a -threaded fastener that is forcibly
mechani,cally interlocked or clinchingly attached to a portion
of sheet ma-terial,
Reerence is made to my related Canadian patent
application, Serial No. ~47,~23, filed February 3, 1984. The
present invention disclosed herein includes variations on the
inventive principles disclosed in said rela-ted application.
It is frequen-tly desirable to secure objects to a
member formed from a rela-tively thin sheet of material, such
as sheet metal. Because such sheet material is generally too
thin to form a threaded hole therein by drilling and tapping,
a threaded female fastener or nut is fre~uently welded or
otherwise secured to such sheet material, thus allowing a male
fastener to be threadably secured thereto.
Alternatively, it may be desirable to provide a threaded
male fastener extending from such sheet material in order to
allow another objec-t to be mounted thereto by means oE a threaded
female fastener. In such a case, -the head of a bolt may be
welded or otherwise secured to such sheet material.
In one known method of securing a threaded fastener to
sheet material, a specially formed clinch nut is fabrica-ted
with a pilot por-tion extending Erom one of its faces. The pilot
is smaller than the remainder~of the nut and thus forms one or
more shoulder portions thereon. The pilot is inserted into a
preformed opening in the sheet material and deformed to flow
outwardly, therby interlockingly engaging the edges of the
~erformed ho]e in the sheet material.
In another me-thod oE securing a threaded fastener to she_t
82~ii5
ma-terial, a specially formed pierce nut with a pilot is provided
which is specially adap-ted to pierce or punch an opening as
-the nut is forcibly urged against the sheet material. Specially
formed dies on a press appara-tus deform the sides of the pilot
and the opening in the sheet material to form a clinch-type
engagement therebetween. Such specially formed and fabrica-ted
pierce nuts may also include shoulders on the main portion
of the nut for abuttingly engaging the sheet material in order
to a-ttain a more even stress distribution, thereby s-trengthening
the joint between the nut and the sheet material.
The above-described methods and apparatus for
securing a fastener to sheet material suffer the disadvan-tage
of requiring an expensive specially formednutorfastener. Such
methods and apparatus also tend to weaken the sheet material
because o:E the necessity of removing a substantial amount
of sheet material in order to form the opening in which the
fastener is received. In a high production environment, -they
also create a considerable amount of scrap.
The present invention overcomes the above dis-
advantages by allowing standard fasteners such as ordlnary
nuts or bolts to be secured to a sheet ma-terial member, thereby
eliminating the need for the expensive special fasteners described
above. In the disclosed embodiment of the invention, a standard
off--the-shelf square nut or a square-headed bolt is secured
to such sheet material, frequently without preforming an opening
in the sheet material, thereby eliminating or minimizing the
attendant scrap.
According to the present invention there is
provided an assembly which includes a fastener, sheet material,
and a strap formed out of -the sheet material and in-tegral
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.,
5~
wi-th the remainder of the sheet material. The strap engages
a first side of the fastener in order to restrain the fastener
for movement relative to -the sheet material in a firs-t direction.
A portion of the remainder of the sheet material securely
engages a second surface oE the fastener in order to restrai.n
the Eastener from movement relative to the sheet material
in a second direc-tion generally opposi-te the first direction,
the fastener thereby being secured -to the sheet material.
In a specific embodiment of the invention, at
least one lip is formed integrally ou-t of the sheet material
in an offset relationship relative to the strap, the lip engaging
a second surface of the fastener in order to restrain the
fastener from movement relative to the strap in a second direction
generally opposite -the first direc-tion.
~ccording to another aspect of the inventi.on
there is provided a method of securing a fastener to sheet
material utilizing a number of relat.ively movable die means,
the fastener having at least two opposite sides, each of the
sides having an edge thereof. The method includes the step
of positioning the fastener and the sheet material between
the relatively movable die means and forcibly moving the relatively
movable die means toward one another. The fastener is forcibly
urged into the sheet material as the die means are moved relatively
-toward one another so that the die means and the edges of
the fastener coact to forcibly deform the first por-tion of
the sheet material in order to form an integral s-trap in an
offset position relative to the remainder of the shee-t material.
The second portion of the sheet material and the sides of
the fastener are forcibly urged into securing engagement with
one another as the die means are moved relatively towardone another.
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These and other advantages of the invention will beco~e readily
apparent from the following discussion and the acccmpanying arawings.
BRIEF DESC PTI~? OF E DR~NGS
Figure 1 is a perspective view of the fastener ass~bly of the
present invention, illustrating a female fastener secured to sheet
material~
Figure 2 is a cross-sectional view taken along line 2-2 of Figure
1. . .
Figure 3 is a cross-sectional view taken along line 3-3 of Figure
1. ' .
Figure 4 is a perspective vie~ of an alternate fastener asse~bly
according to ~e present invention t~herein a male astener is secured to
sheet material.
Figure S is a cross-sectional view taken along line 5-5 of Figure
4.
Figure 6 is a c~oss-sectional vi~w taken alonq line 6-6 of Figure
4.
l ,
5~5
Figure 7 is ~n elevatiGnal view o~ the press and ~orming die
portions of an apparatus Eor ~ecurin~ a fastener to sheet ~aterial
according to the p~esent inventiun.
Figure 8 is a partial perspective view of the forming die
portion of the Figure 7 apparatus, illustrating a retaining spsing
arrangement for holding a fe~ale fastene~.
Figure 9 is a ~iYW similar to that of Figure 8, illustrating an
alternate retaining spring arsangement for holding a ma~e astener.
Figure 10 illustrates an alternate fastener feeding mechanism
for the apparatus of FigurQ ~.
Figure ll is a view taken along line 11-11 of Figu~e 10.
Figure 12 is a cs~ss-section31 view of the fastener and the
press and die portions of the Figure 7 apparatus, prior to the for~ing
stroke.
Figure 13 is an enlarged cross-sectional view similar to that of
Figure 12, but illustrating the fastener and forming co~ponents at the
end of the forming stroke.
D AILED D scRIprIcN OF THE PREFERRED EMBODIMENTS
Figures 1 through 13 of the drawings illustrate vasious
em~odiments of fasteners s~cured to sheet ~aterial memhers according to
the prcsent invention, as well as an apparatus for forming the assemhly.
For purposes of illustration, the drawings illustrate embodim~nts wherein
a standard syuare nut and a standard square-headed bolt are secured to the
sheet material. One skilled in the art will rea~ily recognize, however,
that other fasteners having othes shapes may also be secured to sheet
material in a similar manne~.
Figures 1 through 3 illustrate a fastener asse~bly 10 in which a
female fastener 12 is sigidly secured to sheet matesial 14. Prio~ tD
assembly, fastener 12 is a si~ple inexpensive square nut having a oentral
~Z2~25~
threaded holc 32, as is shown in phantom line~ ~t l~a. Sheet material 1
includes ~n integral support strap 16 p~sitioned in an offset relaticn
relative to the plane of the remainder of ~he sheet. Support strap 16 i8
offset by means of shearinq alonq the opposite sides 18 of fastener 12, A~
indicated at reference numeral ~0. The sides 1~ of fastener 12 ~e
deforn~d so that the fastener material flows outwardly to fo m a pair cf
spaced protrusions 22 w~ich interlockingly engaqe the sheared edges 20
and so that a pair of flared lips 21 are formed along sheared edges 2~.
m e edges of support strap 16 are also preferably deform~d in a
direction toward and slightly around the fastener, as shown at 24, to
interlockingly retain fastener 12. An opening 3~ is punched or otherwis~
formed in the support strap 16 in align~ent with hole 3~ in the fastener
to allcw a bolt, stud or screw to be threadably inserted into hole 32 for
mounting another merber (not shown) to the assembly.
Figures 4 through 6 illustrate a fastener assembly 40 in which a
male fastener 42 is secured to sheet material 14. In its original form,
fastener 42 is a simple inexpensive square-headed tolt having head 44 and
threaded stud 46. The original form of head 44 is indicated in phant
lines at 44a. Head 44 is secured to the sheet material in a ~anner
similar to that described above in connection with female fastener 12
except that stud 46 protrudes through opening 30 in support strap 16.
Alternatively, however, fastener 42 nay be oriented in a position opposite
to that shown in Figures 4 through 6, with stud 46 extending in the
opposite direction, and thus support strap 16 would not require an opening
3~. ~ccause fastener 42 is otherwise secured to sheet material 14 in the
same ~anner as is described above in connection Figures 1 through 3,
corresponding reference nu~erals are used in Figures 4 through 6.
Ihe e~bodiments of Figures 1 through 6 acco~modate the use 5
standard threaded fasteners with no special configuYations or
pilots being required. m e cost of such standard fasteners has been founa
~Z2~
to be approximately one-half of that of ~any specially shaped
piercing-type fasteners. Furthe~mDre, the resulting strength d ~he joi~t
created ky the fastener assemblies of the present invention have been
found to be superior to joints formed using many specially for~ed
fasteners. Specifically, the pull-out strength of the joint, which is ~he
~trength o~ the joint in resisting a force tendir.g to pull the f~stener
upwardly away fro~ the sheet material, as shown, has been found to be
significantly greater than ~h~t of many prior art fastener asse~blies.
Such improve~ent is believed to be due to the full interlocking engage~ent
with the sheet material on tWD opposite sides of the fastener and to the
support strap 16 extending over Gne face of the fastener. Similarly, the
push-out strength, which is the strength of the joint resistin~ a force
tending to push the fastener a~ay fro~ the sheet s~terial in the opposite
direction, has also been found b~ co~pare favorably with that of the prior
art fastener assemblies.
In Figures 7 through 13, an exe~plary joint-forming apparatus 60
is shown for purposes of illustration. One skilled in the art will
readily recogni~e, hcwever, that other similar apparatus may be used to
acco~plish the objectives of the present inven1:ion.
Apparatus 60 includes a punch assembly 62, shcwn in Figure 12 in
a partially lowered position, and an anvil asse~bly 64. Punch assembly 6~
i5 operatively connected to a ram or press apparatus 66 which drives it in
a reciprocating manner, and also includes a keeper member 68 which has a
bore 69 extending partially therethrough for slidably receiving a circulas
punch 70 and a tubular driver member 72 therein. Driver member 72
includes a die portion 74 on its lcwer end (as shown) and is retained
within bore 6g by a retaining member 76 which allows limited reciprocating
m~vement and prevents rotation of the driver member 72 within bDre 69.
Punch 70, at its upper end ~as shown), abuttingly engages the closed en~
o~ bore 69. A oompression spring 7~ biases driver ~ember 72 out of bore
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l.Z2~5~
69, thereby allcwing the driver member to perform a stripping function, as
will be explained below.
Adjustment nut 116 may be threadably advanced or retracted to
adjust the point of engagement by p~ch assembly 62 and thus the stroke
length of driver member 72. Jam nut 117 lockingly abuts adjustment nut
116 to maintain its axial position on driver member 72.
As illustrated in Figures 3 and 8, a pair of opposed retaining
springs 115 on driver member 72 resiliently engage opposed sides of female
fastener 12 to support it in proper alignment with anvil assembly 64, as
explained below. Alternately, as shown in Figures 5, 6 and 9, a second
pair of opposed retaining springs 118 are also used to resiliently engage
corresponding sides of male fastener 42. Springs 118~ are shorter than
springs 115, to avoid interfering with the forming of protrusions 22 on
the fastener, and thus engage the sides of fastener 42 only when head 44
is in its original form 44a, as shown in Figure 5. One skilled in the art
will readiy recognize that similar retaining spring arrangements may be
employed for fasten~rs having other than four-sided heads.
Anvil assen~ly 64 includes a fixed die me~ber B4 having a die
surface 86 thereon. Die portion 74 and die me~ber 84 each have a pair of
spaced shoulders 75 and 85, respectively, which deform the sides of the
fastener, as shown in Figure 13, to form the protrusions 22 thereon (see
Figures 2 and 5). A pair of cutting members 88, in the form of die
blades, are pivotally connected to the fixed die member 84 by means of a
pair of pivot pins 90. Die member 84 includes a pair of integral
shoulders 114 61 idably abutted by oorresponding surfaces 112 on cutting
members 88. Thus, any vertical forces on the cutting members 88 are thus
transmitted directly to die member ~4 and are not absorbed by pins 90, as
is fully described in my above-referenced related applications. A
corresponding pair of com~ression springs 92 bias the cutting members B8
toward their positions adjacent die surface 86, as shown in Figures 12 and
. ~
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13. Fixed die ~ nber B9 also includes a bore 96 extendin9 therethrough,
which communicates with bore 117 in an adjusting screw 119 and is
configured to acccmmcdate punch 70 and to provide for disposal of the
blank 102 of sheet material which is removed by punch 70.
~ or purposes of illustration, the Gpera~ion of apparatus 60 is
described herein in connection with the attach~ent of a female fastener to
the sheet material, substantially in Gne operation. As will be readily
recogni~ed by one skilled in the art, however, the operation of apparatus
60 in connection with the use of a male fastener is similar, with the
minor exceptions noted belc~.
Figures 10 and 11 illustrate an auto~atic fastener feed apparatus
140 for use with forming apparatus 60 in lieu of the retaining springs
discussed above. A fastener feed chute 142 serially transports a number
of fe~ale fasteners 1~ by qravity or under air pressure to a fastener
carrier mechanism 144. A retractible pin 14~, which may be actuated in
any suitable manner, holds back the supply of fasteners until the carrier
mechanism is cleared.
The carrier mechanis~ 144 includes an opening 150 having a
cross-sectional shape corresponding to the cross-section of the fastener
to ensure proper fastener orientation and alignment with die portion 74
and die ~ember 84 during the forming operation. ~ plurality of balls
152, biased by springs 156, extend partially into cpening 150 to support
the fastener until it is engaged by driver member 72. As the fastener is
urged downwardly, springs 156 co~press and balls 152 retract, and the
fastener is forced through opening 150 to engage sheet material 14, as
discussed below.
One skilled in the art will ~eadily recognize that similar
apparatus ~ay be employed for auto~atically feeding male fasteners 42 to
forming apparatus 60. In such an apparatus, for example, chute 142 would
include a longitudinal slot for receiving st~d ~6, thus allc~ing head 44
~L2~8~55`
~o be transport~d in a nanner similar b~ that sh~wn in the drawings fs~
fastener 12. Carrier mechanism 144 would also include a corresponding
vertical slot to provide clearance for stud 46 at the junction with chute
142.
Referring p~ma2ily t~ Figures ~2 and 13, the OQeration of
apparatus 60 is as follows. Sheet material }4 is po6itioned over anvil
assembly 64 so that the area in which the fastener assembly is to be
formed lies ~irectly belo~ punch assembly 62~ Fastener 12 is loaded onto
driver member 72, with punch 70 e~tendin~ ~hrough hole 32 if opening 30 is
desired. Ihe 1ioaaing of fastener 12 on apparatus 60 may be acc m plished
manually, as shown i~ Fi~ure 12, or b~ ~eans of an automatic feed
~echanism, such as ~hat ill~strated in Fig~res lO and 11.
Ra~ 66 is then f~rther aet~ea to drive punch ~se~ly 62
downwardly, where~y F~ 70 ~or~s openin~ 3~ and die portion 74 forcibly
presses fastener 12 against sheet ~ateria1 14 (after keeper me~ber 68 has
moved int~ an abutting relationship ~ith driver member 72). If an
opening havin~ a la~ger d~ametex than ~he inside dia~eter of threaded
hole 32 is desi~ed, it may be pre-formed in the sheet material. Blank
102, resulting from the forming of open~ng 30, drops into bore 96 for
disposal. Thereafter, die portion 74 presses fastener 12 against the
sheet material 14 with sufficient force that the leading edges or corners
of ~he opposite sides lE coact with the inner edges of ~ie blades 88 to
cause the sheet ~aterial to be sheared or lanced along sides 18. Ibe
fastener continues to be forced through the sheet material to offset
support strap 16 in abutting and oonforming engage~ent with the face of
the fastener.
Once sup~ort strap 16 contacts shoulders 85 on die mr~ber 84,
both fastener 12 and support strap 16 are further deformed between
shoulders 75 and 85 tD cause the material of fastener 12 to begin to
flcw outwardly, forming protrusions 22 which interlockingly engage edges
_ g _
, . .
.
,: .
255
20 of the sheet ~aterial. As prot~usions Z2 are formed, cutting members
88 are pivoted outwardly as shown in Figur~ 13. Continued deformation of
support strap 16 and fastener 12 also causes edges 20 to bend toward die
m~mber B4 to form the flared lips 21 shown in ~igures 2 and 5. ~ portion
of support strap 16 is al50 deformed to interlock with the ~ides 18 as a
result of the abo~ deformation.
Driver member 72 restrains the fastener as the punch 7~ retrac$s,
thereby aidinq in the stripping of punch 70 from hole 32. As punch
assembly 62 continues to retract, driver ~ er 7~ is raised s~ tha~ the
sheet material may be removed.
m e apparatus for attaching fastener 42 to the sheet ~aterial is
similar to that described above. ~ecause stua 46 p~otrudes frQ~ head 44,
however, opening 3D in support strap 16 is preferably pre-punched so that
stud 46 may be inserted therein, and faste~er asse~b1y 4Q IS ~hen formed
as described above. If, however, fastene~ 42 is tD be oriented wit~ stud
46 protruding away fro~ support strap 16, pre-punching would not be
required.
The sheet material may be embossed in an area surrounding the
fastener, if desired, to create a flush, generally coplanar relationship
between the sheet material and a faoe of the fastener. Such e~bossing may
be performed prior to securing the fastener to the sheet material or
simultaneously therewith by F~ans of specially formed die surfaces.
The foregoing disc~ssion and the acco~panying drawinqs disclose,
illustrate and describe merely exemplary methods and ~rbodiments of the
present invention. One skilled in the art will readily recognize froQ
such discussion and drawings that various changes, modifications and
variations may be made therein without departin~ from the spirit and scope
of the invention as defined in the following claims~
