Note: Descriptions are shown in the official language in which they were submitted.
12 !335~7
1~2.359
FASTENING ELEMENT, METHOD OF ATTACHMENT
AND PANEL ASSEMBLY
RELATED APPLICATIONS
This application is related to my co-pending U.S.
application Serial No. 773,387, filed September 6, 1985, now
U.S. Patent 4,633,560 which application was a division of Serial
No. 563,833, filed December 21, 1983, now United States patent
No. 4,555,838. That patent is related to U.S. applications
Serial Nos. 458,099, filed March 28, 1983, now United States
Patent No. 4,459,073 and Serial No. 504,074, filed June 14,
1983, now United States Patent No. 4,543,701. Such cases were
related to U.S. application Serial No. 229,274, filed January
28, 1981, now abandoned, which claimed priority from a published
application filed February 2, 1980 in the Federal Republic of
German~ No. 3 003 908.
FIELD OF THE INVENTION AND
SUMMARY OF THE PRIOR ART
The present inYention relates to an improved riveting or self-
attaching element, such as a stud, bolt, nut or the like which is att~ched to a
p~nel and which includes a riveting portion.
As disclosed more fully in my Above-referenced related U.S. applications
and pfltents, the prior art discloses various means of attaching an eleT~nt to a
panel. The f~stening elernent of this invention is particulQrly ad2pted for
attachment to a rel~tively thick panel having a preformed or prepierced panel
opening. Various methods and fastening elements have been disclosed -and
described in the prior ~rt for att~chment to a pQnel or plate having a preformed
opening, including United States Patent No. 1,953,197 which discloses a rnethod
of ~ttsching ~ b~ll element of a ball pint to an engine cylinder, I~.S. Patent No.
3~432,925, which discloses various methods of securing a riYet contact, U.S.
-1-
~2835Z~
52.3 j9
Patent No. 3,556,189, which discloses methods of attaching studs in B blind hole
and U.S. Paten~ No. 4,193,333, which discloses a clinch-type fastener and
method of attaching a stud-type elernent to a relatively thick panel. Reference
is also ~de to the prior art cited in my above-identified related U.S. applications
~nd patents.
The disclosures of my above-identified related U . S . applications
patents were primarily concerned with fastening elements and methods of
attaching such elements to a metal panel such as used by the automotive
industry for body p~nels, structural elements and the like h~ving a thickness
generally less than about 2.Smn or 0.098 inches. ln fact, Qn object of such
fQstening elements was to permit attachment to relstively thin panels, including
panels having ~ thickness of about û.031 inches, in a continuous operation,
preferably including piercing the panel. The disclosed festening elements and
methods of installation are still preferred in most automotive applications,
however, the need remains for a fastening element suitable Eor installation in
relatively thick or heavy guage metal panels, including panels having a thickness
ranging from about 0.06 to 0.3 inches or greater.
The prior art methods of attachment and self-fastening elernents cited
above are not suitable for rn~ny applications, particularly in relatively heavy
guage panels used for automotive applications. Such automotive applications
have minimurn st~ndards of push-through and pull-off, requiring joint integrity in
both directions. Further, the fastener cost must be kept at a minimum and the
rrethod of installation must be relatively simple, permitting automation of the
installation process. Because of these difficulties, stud or bolt-type fasteners
are norrnally attached to relatively thick panels in automotive applications by
welding~ The method of attaching a weld stud or fastener generally does not
pemlit very accurate location of the stud on the panelS welding methods
require inspection of the weld joint, and weld methods on galvanized metals emit
toxic vapors. Thus, welding methods ~re not suitable for meny automotive
--2--
1~2.35~ ~Z~Z7
applications, particularly where the fastener must be very accurately located on
the panel or the connection cannot be easily inspected.
The need therefore remains for a fastening element and method of
attaching a fastening element to a relatively heavy guage panel, including
panels having a thickness greater than about 0.1 inches. The fastening element
and method of this invention solves the problems associated with the prior art in
a manner which permits automation of the installation method and the fastening
element and method are suitable for automotive applications.
SUMMAR Y ~F THE INVENTION
The self-fastening or riveting element of this invention includes a
body portion and an integral annular barrel portion having external and internal
surfaces terminating in a free end. The external surface of the barrel portion
includes a conical surface portion which is tapered outwardly from adjacent the
free end. The barrel portion in the most preferred embodiment of the invention
includes a cylindrical external surface adjacent the free end which guides the
barrel portion into the panel opening or aperture and which is riveted or
deformed in a die member to permanently attach the fastening element to the
panel. In the preferred embodiment of the stud-type or male fastening element,
the barrel portion is closed and a stud, bolt or other element extends integrally
from the closed end of the barrel portion, preferably in coaxial alignment with
the barrel portion.
As described, the method of attachment of this invention is
particularly adapted for relatively thick panels, such as used by the automotive
industry for structural elements, including 'brackets, frame elements and the like.
The fastening element and method of this invention is particularly adapted for
securement in a panel having a thickness greater than about 0.1 inches and the
fastening element has been successfully installed in panels having a thickness of
1~2.35~ ~2a3~iz7
0.31;) inches and greater. It will be understood, however, that the fastening
elemen~ and metho~ of in~stallation of this invention may also be used for thinner
panels having a thickness of about 0.06 inches, for example. It is believed,
however, that the methods of installation and self-fastening elements disclosed
in my above-identified related applications and patents will be more suitable for
panel thicknesses less than about 0.1 inches.
l`he method of this invention includes forming a generally circular
aperture through the panel having a cylindrical internal surface with a diameter
generally about equal to the minor diameter of the conical surface on the barrel
portion. That is, the diameter of the panel aperture should be generally equal
to or slightly less than the minor diameter of the conical surface, which is the
diameter of the cylindrical portion of the barrel in the preferred embodiment of
the fastening element. The cylindrical external portion of the barrel guides the
barrel portion into the panel aperture. The method next includes locating the
fastening element barrel portion free end adjacent the panel with the annular
barrel portion generally coaxially aligned with the panel aperture and a die
member located on the opposite side of the panel. The die member includes an
annular concave die cavity surrounding a central portion having an exterior
diameter generally equal to the diameter of the internal barrel surface and
coaxially aligned with the barrel portion.
The method next includes driving the barrel portion free end through
the panel aperture, into the die cavity and the remaining steps are preferably
performed in a continuous operation, nearly simultaneously. The conical surface
of the barrel portion is driven against the cylindrical internal surface of the
panel aperture, press fitting and reforming the internal surface of the panel
aperture into a mating conical surface which resists further penetration of the
barrel portion through the panel aperture. Sirnultaneously, the free end of the
barrel portion is deformed radially outwardly in the die cavity and reversed
against the panel, forrning a radially outwardly extending annular rim, which is
~2~3~27
52.359
hook-shaped in cross-section, wherein the free end of the barrel portion is
biased against the panel, spaced radially outwardly from the panel aperture.
The hook-shaped end portion of the barrel thus prevents removal of the
fastening element from the panel in the direction opposed to the direction of
installation. The cone-shaped surfaces of the panel and barrel portion thus
cooperate with the hook-shaped rim portion formed in the end of the barrel to
prevent push-through or pull-out of the fastening element, which is thereby
permanently attached to the panel.
In the most preferred method of this invention, the free cylindrical
end portion of the barrel is entrapped in the die cavity and simultaneously
thickened and deforrned radially outwardly, forming an enlarged hook-shaped
portion which is resiliently biased against the panel, for~ning a very secure
installation. Because of the thickness of the panel, it is generally not possible
to draw the panel into the die opening or deform a substantial portion of the
panel into the annular rim formed in the barrel portion. In the preferred
method, however, a small circular rim may be Eormed in the panel, which extends
into the annular barrel portion rim adjacent the minor diameter of the panel
aperture and which provides a mechanical interlock between the panel and the
barrel portion.
The preferred embodiment of the self-attaching element includes an
annular driving surface which extends generally perpendicular to the axis of the
annular barrel portion for driving the barrel portion into the preformed panel
opening. The internal surface of the barrel portion rnay be generally
cylindrical, threaded or unthreaded, proYiding a sirnple and inexpensive
construction. As will be understood, the resultant panel assembly includes
rn0ting press-fitted conical surfaces on the exterior of the barrel portion and
the panel aperture which resist penetration of the barrel portion, and the barrel
portion includes a U or hook-shaped annular rim having a free end portion which
is preferably resiliently biased against the panel spaced from the panel aperture.
3~;27
15~.3~
In the disclosed embodiment, the barrel portion retained in the panel aperture is
generally disk-shaped having an annular shoulder which is flush-mounted in the
panel and which closes the end of the barrel portion. The fastening element
may also include a body portion which extends from the plane of the disk-shaped
portion. The body portion may include or comprise a secondary fastening
element, such as a stud, bolt, ball element or the like. Alternatively, the barrel
portion may comprise a secondary fastening element, such as a nut fastener.
Other advantages and meritorious features of the fastening element,
method of attacl~nent and panel assembly of this invention will be more fully
understood from the following description of the preferred ernbodiments,
appended claims and the drawings, a brief description of which follows.
BRIEF DESCRIPTION OF T~E DRAWINGS
Figure 1 is a partially cross sectioned side view of a self-attaching
stud being installed in a panel and elements of the installation apparatus
including a die member and plunger;
Figure 2 illustrates the continuing sequence of installation of the stud
; member shown in Figure l;
Figure 3 illustrates the panel assembly formed by the stud mernber and
method of installation of Figures 1 and 2;
'~
Figure 4 is a partially cross sectioned side view of an embodiment of
the self-attaching element of this invention, suitable for installation in
relatively thick panels, and elements of the installation apparatus;
Figure 5 is similar to Figure 4 except that the self-fastening element
has been partially insta~led in the panel;
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3~9 ~2~33~27
Figure 6 is a side partia~y cross-sectioned vie~ of the ~ssennbly shown
in Figures 4 and 5 fo~owing insta~ation of the self-fastening ele ~ nt; and
Figure 7 is an enlarged partial view of Figure 6.
DESC RlPrIO~ OF T HE PREFER RED EM BO DIMENTS A N D METH O D
The fo~owing detailed description of the preferred embodinnænts and
thod references copending United States patent application Serial No.
773,387, filed Septennber 6, 1985 and United States Patent No. 4,555,838, which
issued fr ~ the parent Qpplication of the copending application. Figures 1 to 3
of this applicstion are t~ken from the above-referenced copending application
and patent and disclosç the preferred ennbod~nænts of the self-piercing and
riveting nn~le-type fastener and nnethod of insta~ing the fastener in ~ "thin"
panel. As described, this method is sti~ preferred in p~nels h~ving Q thickness
up to about 0.1 inches because the nnethod does not require ~ preforned or
prepierced panel ~perture and the ~ thod nnay be perfo m ed in a single
continuous operation~ including piercing. Reference is also made to my
copending applicati.on Serial No. 657,570, filed October 4, 1984,
now U.S. Patent 4,610,072 which was related to U.S. application
Serial No. 563,833, now U.S. Patent No. 4,555,838. The '072 patent
discloses alternative methods of installing ~emale-type fasteners in
a continuous operation.
Figures 1 to 3 illustrate the preferred insta~ation sequence and
nnethod of insta~ing the stud-type fastener 20 in a relatively thin psnel 22 as
disclosed in the above-identified copending epplication serifll No. 773,387, f~ed
Septen~ber 6, 1985 ~nd the p~rent application which issued ~s United States
Patent No. 495551838. The disclosed stud-type fastener includes a head portion
24 in the fo~n of a radial flange, an unthreaded shank portion 26 ~nd a self-
piercing and riveting annul~r barrel portion 28. The outer or exterior surface
30 of the annular barrel portion in the disclosed ~nnbodLm~nt is generally
.
, . , , . . ~
., .
'
~2~5~
~2.359
cylindric~l and terrninates in a rounded driving and drawing surface at the
radial~y outer surface of the free end 32 of the barrel portion. The barrel
portion includes a central recess or opening 34 which is defined by the
cylindrical internal surface 36 and the bottom wall 38. The inner surface 36 of
the barrel portion terminates in an annular piercing surface 40 ~djacent the free
end 32 of the barrel portion. The bottom wall 38 in the disclosed ernbodiment isconical and concave, as shown in Figure 3.
The top surface 44 of the head portion 24 includes an annular driving
surface adjacent the shank 26 and the bottom surface 46 of the head defines an
annular bearing surface. It will be understood that "top" and "bottorn" are
relative terms depending upon the orientation of the fastener and are used
herein only for descriptive purposes. The fastener of this invention may be
attached with a die member or button located either on the top or the bottom
shoe of a die press, for example. Further, the annular barrel portion 28 may be
OI any annular configuration, including cylindrical, as shown, hexagonal,
octagonal, etc. The disclosed embodiment, however, is relatively sirnple and
provides excellent retention, as described below.
The installation method disclosed in Figures 1 to 3, begins with
orienting the stud fastener 20 relative to the panel 22 and the die mernber 50.
The die member includes a panel supporting or seating shoulder 52 which
surrounds an annular die cavity 54. The annular die cavity 54 surrounds a
central die portion 56 which includes a convex conical surface 58, preferably
including a rel~tively sharp apex 60 ~nd the conical surface surrounds an
annular surfQce 62. The ~nnul~ die cavity 54 includes an inclined or sloped
outer surface 64 which blends into a panel supporting shoulder or lip 66 through
a ~ oth ercuate surface. The bottorn surface 68 of the annular die cavity is
semi-toroidal and tenninates in the annular shoulder or p~nel supporting lip 66.
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~2~33~27
152.35
As shown in Figure 1, the panel 22 is first deformed into the annular
die cavity 5~. The panel is first engaged by the free end 32 of the annular
barrel portion. The panel portion located inside the annular wall is then domed
or trepanned against the conical surface 58 of the free end of the central
projecting die portion 56/ fixing this portion of the panel prior to piercing or
shearing, as now described.
The panel is then pierced or sheared as shown in Figure 2. The panel
is sheared between the piercing surface 40 of the annular barrel portion and the
piercing edge 70 located at the outer edge of the proiecting central die portion
56, forming a panel slug 75 which is disposed within the fastener barrel portion
recess 34 on the conical free end 58 of the projecting die portion. It will be
understood that the configuration of the die member piercing ~dge 70 should be
the same as the configuration of the annular wall 28, such that the mating
piercing surfaces pierce the panel. The piercing surface 40 of the barrel
portion is preferably a chamfer face inclined outwardly from the axis of the
annular barrel portion. The she~ring of the panel then occurs along the
shearing face 40, forming a panel slug 75 having an external diameler slightly
greater than the internal diameter of the inner surface 36 of the annular wall,
providing an interference fit. The inclined piercing face 40 is "self-
correcting" and assures a clean shearing of the panel with a minimum of force.
Figure 3 illustrates the final configuration of the stud-type fastener
20 and the panel assembly. The annular barrel portion 28 now includes a first
tubular portion 80 ~nd a second radially outwardly hook-shaped end portion 82,
however, the barrel portion has generally the same thickness as the original
configuration. The slug 75, which was pierced from the main portion of the
panel 22, has been deformed against the bottom wall surface 38 of the barrel
portion recess by the conical free end 58 of the central projecting die portion
56. The panel slug becomes an integral part of the fastener and panel
assembly. The panel 22 now includes a rnain portion 22 bearing against the
_g_
152.359 1;~35~7
panel supporting shoulder 52 of the die button, a second portion 84 drawn and
displaced form the plane of the main panel portion and ccnforming to the
inclined outer wa~ 64 of the die cavity and the annular lip 66J which has limited
the defor~tion of the panel into the die cavity and which supported the panel
during the final deformation of the panel in the hook-shaped end portion 82 of
the barrel portion. During the final insta~ation, the panel portion surrounding
the pierced panel edge is driven into the developing hook-shaped channel 82 of
the barrel portion, thickening the panel portion as shown at 86. As disclosed
more fu~y in the above-identified copending application, the insta~ation
apparatus includes an insta~ation head (not shown) which receives the stud
fasteners and which includes a reciprocal plunger 90 having a bore 92 which
receives the shank portion 26 of the fastener and an annular driving surface 94
which bears against the annular driving surface 44 of the fastener and which
drives the barrel portion 28 of the fastener into the panel, as described above.
H~ving described one embodiment of a self-piercing and riveting stud-
type fastener and the method of insta~ation, it wi~ be understood that there is
a practical limit to the thickness of the panel 22 to which the self-piercing and
riveting f~stener 20 may be attached. First, the barrel portion 28 must pierce
the panel 22, limiting the thickness of the panel. Further, the panel is drawn
into the die opening, as shown in Figures 1 and 2, and the panel is then driven
into the developing hook-shaped end portion 82, fo~ning a thickened end portion
~6, which is entrapped within the hook-shaped barrel portion. ~f course, the
thickness of the panel to which the fastener ~ y be attached will also be
dependent upon the size and thickness of the barrel portion. The size of the
barrel portion is, however, dete~nined in practical application by the size of the
bolt. Thus, an alternative design and method of insta~ation is necessary to
acconl~odate relatively thick panels for conventional bolt sizes, as described
~bove.
~igures 4 to 7 i~ustrate an alternative ennbodiment of the self-
.
--10-
~L2~3352752.35'
fastening element of this invention particularly adapted for attachrnent to a
relatively thick panel or a panel having a substantial thickness, i.e., gr~ater
than about 0.1 inches and including thicknesses greater than 0.3 inches. An M8
stud (stud having a thread crest diameter of 8~n) of the type disclosed, for
example, is suitable for attachment to a panel having a thickness of 6mn and an
Ml2 stud can accommodate an 8mn panel. Again, the illustrated self-fastening
element is a stud-type fastener having a body portion 102 in the fo~n of a male
threaded bolt, and an annular barrel portion 104. The barrel portion in the
disclosed ernbodiment includes a generally cylindrical internal surface 106 and an
external surface including a cylindrical end surface portion 108 and a conical
surface portion 110. The barrel portion includes a free end 112, which in the
disclosed and preferred embodiment is a convex arcuate surface which joins the
internal and external surfaces of the barrel portion. The barrel portion definesan internal cavity 11~ which is enclosed by bottom wall 116. In the disclosed
embodiment, the bottom wall 116 also defines a disk-shaped body portion having
a conical outer surface 110 and a top driving surface 118.
~ s described above, the panel 120 may be relatively thick and the
panel preferably includes a preformed or prepierced cylindrical aperture 122.
As shown, the diameter of the aperture 122 is generally egual to the minor
diarneter of the cone-shaped surface 110, which is the diameter of the
cylindrical surface 108. The cylindrical annular end portion of the barrel
portion guides the barrel portion into the cylindrical panel aperture 122, as
shown in Figure 4. As will be understood, the barrel portion 104 is aligned with
the panel aperture, and a die member 124 is located on the opposite side of the
panel. The die member includes an annular concave die cavity 126 having an
internal surface 128 which closely receives the internal surface 106 of the
barrel portion. The concave die cavity is serni-toroidal, but the die cavity does
not include a panel receiving lip, as described above in regard to Figures 1 to
3, because the panel is not deformed into the die cavity. The die member does
include a central die portion 130, which in the disclosed err~odiment includes a
~IL283~27
~.359
conic~l end portion 132.
As disclosed more fully in the above-identified copending U.S. application
and ll.S. Patent No. 4,555,838, the install~tion ~pp~rstus includes R plunger 134
having an annul~r surf~ce 136 which drives the fastener into the panel. The
disclosed embodirnent also includes a gage pin 138 which indicates the presence
- of a fastening element in the bore 140 of the plunger, ready for installation.
As described in the copending ~pplication, the fastening elements are serially
received in the installation head ~nd located in the plunger ready fo
instflllation.
Figures 4 to 7 illustrate tbe method of installation and Installation
sequence of this invention. Pirst, BS described, the barrel portion 104 of the
fsstening element is located adjacent the panel with the barrel portion coaxially
aligned with the panel aperture and the die mernber, as shown in Figure 4. The
free end 112 of the barrel portion 104 is then driven through the panel aperture
122 into the die cavity 126 by the plunger 134 as shown in Figure 5. The
conical extern~l surface 110 of the barrel portion is press fitted into the
cylindrical aperture 122 in the panel, deforming the internal cylindrical surface
of the aperture apd forrning a mating conical surface. The free end 112 of the
barrel portion is simultaneously deformed radially outwardly against the semi-
toroidal concave die cavity surface 126. As best shown in Figure 6, the
cylindrical end portion of the barrel portion is deformed in the annular die
cavity to substantially fill the annulHr die cavity and entrapped therein to form
a thickened annular channel 140 which is hook-shaped in cross section and
wherein the free end 112 of the barrel por~ion is resilien~ly biased ugainst the
bottom surface 142 of the p~nel, spaced radially from the panel sperture 122.
As shown in Figures 6 and 7, the cylindrical surf~ce of the panel aperture h~s
been deformed into a conical surface 122~, which fuUy mates with the conic~l
surface 110 of the barrel portion, limi~ing further penetration of the barrel
portion into the panel opening. Further, the annular driving surface 118 is
--12-
.,
~Z83~27
152.359
driven flush with the top surface 144 of the panel, such that the threaded bolt
portion 102 extends from the plane of the panel 144.
As best shown in Figure 7, the edge of the panel 120 adjacent the
panel opening 122a is deforrned slightly to improve the retention of the
fastening element to the panel. A small circular lip 146 is formed into the
annular channel or hook-shaped portion 140, providing a rrechanical interlock
between the barrel portion and the panel. The mating conical surfaces 110 and
122a thus prevent "push-through" of the fastening element through the panel
opening in the direction of the installation of the fasterling element. The
enlarged hook-shaped annular channel 140, including the free end 112 which is
resiliently biased against the bottom face 142 of the panel, prevents 'lpull-out"
in the opposite direction. The panel assembly is therefore quite secure,
particularly in a panel of substantial thickness, as described above.
As will be understood, the configuration of the fastening element 100
may be modified as reguired by the application. Thus, the male threaded shank
102 may be replaced with an Imthreaded shank, a ball member for a ball and
socket joint, a hinge member or removed entirely to form a female element, such
as a nut fastener, in which case the internal surface 106 may be internally
threaded. Other modifications may be made to the fastening element, method of
installation and panel assembly of this invention within the purview of the
appended claims.
~`~
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~ -13-
