U.S. patent application number 10/714265 was filed with the patent office on 2005-05-26 for self-riveting male fastener and panel assembly.
Invention is credited to Ladouceur, Harold A..
Application Number | 20050111934 10/714265 |
Document ID | / |
Family ID | 34590858 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050111934 |
Kind Code |
A1 |
Ladouceur, Harold A. |
May 26, 2005 |
Self-riveting male fastener and panel assembly
Abstract
A male fastener formed of heat treated carbon steel for high
performance applications, including a shank portion, radial flange
and tubular barrel, wherein the barrel has an axial length of 60%
or less than the outside diameter and a fastener and panel
assembly, wherein the distal open end of the barrel is deformed
into an L-shape and the panel is deformed by the radial flange into
an L-shape having an inwardly projecting portion deformed between
the radial flange and the outwardly deformed distal end of the
barrel.
Inventors: |
Ladouceur, Harold A.;
(Livonia, MI) |
Correspondence
Address: |
HOWARD & HOWARD ATTORNEYS, P.C.
THE PINEHURST OFFICE CENTER, SUITE #101
39400 WOODWARD AVENUE
BLOOMFIELD HILLS
MI
48304-5151
US
|
Family ID: |
34590858 |
Appl. No.: |
10/714265 |
Filed: |
November 14, 2003 |
Current U.S.
Class: |
411/501 |
Current CPC
Class: |
F16B 37/068 20130101;
Y10T 29/4992 20150115; B23P 19/062 20130101 |
Class at
Publication: |
411/501 |
International
Class: |
F16B 019/08 |
Claims
1. A male self-riveting fastener element, comprising: a shank
portion and an integral tubular barrel portion having a
substantially constant cross-section including a generally
cylindrical outer surface, a cylindrical inner surface, and an open
distal end coaxially aligned with said shank portion, wherein said
tubular barrel portion has an axial length equal to or less than
sixty percent of an outer diameter of said generally cylindrical
outer surface of said tubular barrel portion.
2. The male self-riveting fastener element as defined in claim 1,
wherein said fastener element is formed of a high strength carbon
steel having a hardness greater than the 30 Rockwell on the C
scale.
3. The male self-riveting fastener element as defined in claim 1,
wherein said male self-riveting fastener element includes a radial
flange portion integral with said tubular barrel portion including
a diameter greater than said tubular barrel portion having a
generally cylindrical outer surface including a plurality of
equally circumferentially spaced radial teeth.
4. The male self-riveting fastener element as defined in claim 3,
wherein each of said equally circumferentially spaced radial teeth
include a generally radial planar surface extending generally
perpendicular to a circumference of said outer surface of said
radial flange portion.
5. A self-riveting male fastener element, comprising: a shank
portion, an integral radial flange portion having a diameter
greater than said shank portion including an outer surface, and a
tubular barrel portion integral with said radial flange portion and
coaxially aligned with said shank portion, said tubular barrel
portion having an axial length equal to or less than sixty percent
of an outer diameter of said outer surface of said tubular barrel
portion and said male fastener element formed of carbon steel
having a hardness greater than 30 Rockwell on the C scale.
6. The self-riveting male fastener element as defined in claim 5,
wherein said outer surface of said radial flange portion includes a
plurality of circumferentially spaced radial teeth.
7. The self-riveting male fastener element as defined in claim 6,
wherein each of said circumferentially spaced radial teeth include
a generally radially extending planar surface extending generally
perpendicular to a circumference of said outer surface of said
radial flange portion.
8. A self-riveting male fastener and metal panel assembly,
comprising: a self-riveting male fastener formed of carbon steel
having a hardness of at least 30 Rockwell on the C scale including
a shank portion, a flange portion integral with said shank portion
having a diameter greater than said shank portion having an outer
surface, and a barrel portion coaxially aligned with said shank
portion, said barrel portion including a tubular barrel portion
integral with said flange portion and a generally radially
outwardly extending distal end portion spaced from said flange
portion; and a metal panel including a planar portion surrounding
said outer surface of said flange portion, and an L-shaped portion
integral with said planar portion including a portion integral with
said planar portion extending generally perpendicular to said
planar portion deformed into said outer surface of said flange
portion in substantially face to face contact therewith and a
radially inwardly directed portion deformed between said flange
portion and said generally radially outwardly extending distal end
portion of said barrel portion.
9. The male fastener and metal panel assembly as defined in claim
8, wherein an overall length of said barrel portion, including said
tubular portion and said generally radially outwardly extending
distal end portion is equal to or less than sixty percent of an
outer diameter of said tubular portion of said barrel portion.
10. The male fastener and metal panel assembly as defined in claim
8, wherein said generally radially outwardly extending distal end
portion of said barrel portion has a width equal to about one half
or less than a width of said planar portion of said panel.
11. The male fastener and metal panel assembly as defined in claim
8, wherein said generally radially outwardly extending distal end
portion of said barrel portion extends generally parallel to said
planar portion of said metal panel and is generally rectangular in
cross-section.
12. The male fastener and metal panel assembly as defined in claim
8, wherein said outer surface of said radial flange portion
includes a plurality of circumferentially spaced generally radial
teeth each having a generally cylindrical outer surface and said
inner surface of said L-shaped portion of said panel is deformed
against said generally cylindrical outer surface and between said
circumferentially spaced generally radial teeth preventing rotation
of said male fastener in said metal panel.
13. The male fastener and metal panel assembly as defined in claim
12, wherein each of said plurality of circumferentially spaced
radial teeth include a planar generally radial surface extending
generally perpendicular to a circumference of said outer surface of
said radial flange.
14. The male fastener and metal panel assembly as defined in claim
8, wherein said barrel portion has a bottom wall at said radial
flange portion and a substantially continuous convex arcuate
surface extending from said bottom wall to a distal end of said
generally radially extending distal end portion.
15. A male fastener and panel assembly, comprising: a carbon steel
male fastener having a shank portion, a flange portion integral
with said shank portion having a diameter greater than said shank
portion including a generally cylindrical outer surface, and a
barrel portion coaxially aligned with said shank portion including
a tubular portion integral with said flange portion and a generally
radially outwardly extending distal end portion spaced from said
flanged portion, said barrel portion having an overall length
including said tubular portion and said generally radially
outwardly extending distal end portion equal to or less than sixty
percent of an outer diameter of said tubular portion; and a metal
panel including a planar portion surrounding said outer surface of
said flange portion, and an L-shaped portion including a first
portion integral with said planar portion extending generally
perpendicular to said planar portion having an inner surface
deformed against an outer surface of said flange portion in
substantially face to face contact, and a second generally radially
inwardly extending distal end portion having an opening
therethrough receiving said tubular portion of said barrel portion
deformed between said flange portion and said generally radially
outwardly extending distal end portion of said barrel portion.
16. The male fastener and panel assembly as defined in claim 15,
wherein said male fastener is formed of a carbon steel having a
hardness of at least 30 Rockwell on a C scale.
17. The male fastener and panel assembly as defined in claim 15,
wherein said second generally radially inwardly extending distal
end portion of said panel has a width of about one half or less
than a width of said planar portion of said panel.
18. The male fastener and metal panel assembly as defined in claim
15, wherein said second generally radially inwardly extending
distal end portion of said panel is generally parallel to said
planar portion and has a generally rectangular cross-section.
19. The male fastener and metal panel assembly as defined in claim
15, wherein said outer surface of said flange portion includes a
plurality of circumferentially spaced radial teeth and said inner
surface of said panel is deformed between said circumferentially
spaced radial teeth, preventing rotation of said male fastener
relative to said panel.
20. The male fastener and metal panel assembly as defined in claim
18, wherein each of said radial teeth include a planar generally
radially extending surface generally perpendicular to a
circumference of said outer surface of said flange portion.
21. The male fastener and metal panel assembly as defined in claim
15, wherein said barrel portion has a bottom wall at said radial
flange portion and a substantially continuous convex arcuate
surface extending from said bottom wall to a distal end of said
generally radially outwardly extending distal end portion.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a self-riveting or self-attaching
male fastener and male fastener and panel assembly for high
performance applications requiring greater strength and structural
integrity, wherein the male fastener, such as a stud or bolt,
includes an integral tubular barrel portion which is received
through an opening in the panel and riveted to the panel.
BACKGROUND OF THE INVENTION
[0002] U.S. Pat. No. 4,459,073 assigned to the assignee of the
predecessor in interest of this application discloses an early
embodiment of a self-piercing and riveting fastener of the general
type disclosed herein and method of installing the male fastener in
a panel. As shown in this patent, the male fastener includes a
threaded shank portion, a radial flange portion integral with the
shank portion and a tubular barrel portion integral with the flange
portion and coaxially aligned with the shank portion. The male
fastener is installed in a panel by supporting the panel on a die
member or "die button" and driving the distal end of the barrel
portion against the panel, piercing a slug from the panel and the
deforming the distal end of the tubular barrel portion radially
outwardly and deforming the panel surrounding the pierced panel
opening between the radial flange portion and the L-shape barrel
portion. This embodiment of the self-piercing male fastener and
method of installation in a panel was not commercially successful
because the fastener and panel assembly had insufficient integrity,
including pull-out strength and no means was provided to prevent
rotation of the stud in the panel. U.S. Pat. Nos. 4,915,558 and
5,092,724, also assigned to the assignee of the predecessor in
interest of the assignee of this application, discloses a
commercially successful self-piercing male fastener and method of
installation, wherein the fastener includes a shank portion, a
radial flange portion and a tubular barrel portion as described
above; however, the tubular barrel portion has an axial length
generally equal to the outer diameter of the barrel portion and the
male fastener is installed in a die member having a concave die
surface, including a frustoconical opening and a concave annular
bottom surface joining the frustoconical surface by an annular
radial lip. The distal end of the tubular barrel portion is driven
against a panel supported on the die member, which pierces a slug
from the panel, and the distal end portion of the tubular barrel
portion is deformed in the concave annular guide surface into a
U-shape, wherein the panel surrounding the pierce panel opening is
driven inwardly by the annular radial lip of the die member into
the U-shaped barrel portion, tightly packing the panel between the
radial flange portion and the U-shaped barrel portion. Although
this male fastener and method of installation has been commercially
successful, the male fastener and method of assembly is not
suitable for high performance applications, such as automotive seat
belt retaining studs, wherein the male fastener element must be
formed of a high strength steel, or in applications having a panel
thickness of greater than about 2 mm. It has been found that the
barrel portion will crack when deformed into a U-shape as disclosed
in U.S. Pat. No. 4,915,558, resulting in poor male fastener and
panel assembly integrity.
[0003] High performance applications of this type of fastener also
requires improved torque resistance. U.S. Pat. No. 6,122,816,
assigned to the assignee of this application, discloses a male
fastening element of the type disclosed herein, wherein the outer
surface of the barrel portion is frustoconical and the radial
flange portion includes an outer surface having a plurality of
circumferentially arcuate radially inwardly concave surfaces,
improving torque resistance when installed in a panel. In the
method of installation disclosed in this patent, the radial flange
portion is driven into the panel and the panel is then deformed
into the arcuate radially inwardly concave surfaces providing
torque resistance. Reference is also made to copending U.S.
application Ser. No. 10/271,480 filed Oct. 16, 2002, assigned to
the assignee of this application, which discloses a male fastening
element of the type disclosed herein, wherein the outer surface of
the radial flange portion includes a plurality of
circumferiantially spaced radially projections or teeth which are
driven into the panel during installation and provide greater
torque resistance.
[0004] However, there remains a need for a self-riveting male
fastener or stud of the type described above specifically for high
performance applications, wherein the stud is formed of a high
strength steel suitable for such applications. The self-riveting
male fastener and method of installation of this invention is
particularly suitable for high performance applications, wherein
the stud is formed of a high strength steel which avoids cracking
of the barrel during installation and may be installed in thicker
metal panels as required for safety related applications.
SUMMARY OF THE INVENTION
[0005] The self-attaching or self-riveting male fastener of this
invention is formed of a high strength carbon steel for high
performance applications, such as seat retaining studs and other
safety related applications, including seat belt retainers, passive
restraints and the like. In the preferred embodiments, the
self-riveting male fastener is formed of a high strength steel,
such as 1038 carbon steel and heat treated to a hardness of at
least 30 Rockwell on the C scale or Rockwell C. In a typical
application, the stud will meet Class 10.9, which has a hardness of
32 to 39 Rockwell C. The male fastener may be a stud or bolt
fastener, wherein the shank portion may be threaded or unthreaded
depending upon the application. One embodiment of the male fastener
element of this invention includes a radial flange portion integral
with the shank portion and a tubular barrel portion integral with
the radial flange portion and coaxially aligned with the shank
portion having an open distal end as described above. However, the
barrel portion of the male fastener of this invention has an axial
length equal to or less than 60% of the outer diameter of the
tubular barrel portion. In a preferred embodiment, the tubular
barrel portion has a smooth cylindrical outer surface and a smooth
cylindrical inner surface, such that the barrel portion has a
substantially constant internal and external diameter, except that
the internal surface includes a chamfer and the outer surface is
arcuate adjacent the distal end of the tubular barrel portion, as
is known by those skilled in this art for this type of
fastener.
[0006] Many high performance applications also require significant
torque resistance. That is, the male fastener must be prevented
from rotating in the panel following installation. Although various
antirotation means may be utilized, in the disclosed embodiment the
outer surface of the radial flanged portion includes a plurality of
radially extending circumferentially spaced radial projections or
teeth each having a cylindrical outer surface and a planar surface
extending generally perpendicular to the circumference of the outer
surface of the radial flange portion. Depending upon the
application of the of the male fastener element, the male fastener
element provides torque resistance to turning in either direction.
For example, the shank portion may be threaded and a nut may be
torqued on to the threaded shank portion, requiring torque
resistance in the direction of rotation of the nut as the nut is
threaded or cross-threaded onto the shank portion. However, the nut
may also be unthreaded from the shank for repair or maintenance,
requiring torque resistance in the opposite direction. Thus, in the
disclosed embodiment, each of the circumferentially spaced radially
teeth include planar surfaces on both sides of the radial
projections.
[0007] The male fastener element is installed in a panel by
piercing or pre-forming an opening in the panel having a diameter
generally equal to the outer diameter of the tubular barrel portion
and supporting the panel on a die member or "die button" in a die
press, generally the lower die platen as will be understood by
those skilled in this art. However, because the barrel portion of
the male fastener is shorter than a conventional male fastener of
this type, the die opening is relatively shallow compared to a
conventional die button for this type of installation. The die
button preferably includes a concave annular surface which extends
to the panel support surface and a central planar nose portion. The
male fastener may be received in a conventional installation head
attached to the upper die shoe of the die press which aligns the
tubular barrel portion with the opening through the panel and the
opening through the panel is coaxially aligned with the central
nose portion. The installation head includes a reciprocating
plunger which engages an annular surface of the radial flange
portion and drives the male fastener toward the panel upon closing
of the die press. The distal open end of the barrel portion is then
driven by the plunger through the panel opening into the concave
annular die surface of the die button, deforming the panel radially
outwardly and the radial flange portion is driven into the panel
forming an L-shaped panel portion surrounding the panel opening
including a portion extending perpendicular to the planar panel
having an internal surface which is deformed against the outer
surface of the radial flange portion and a generally radially
inwardly extending portion which is deformed between the radially
outwardly extending distal end portion of the barrel portion,
securely retaining the male fastener element in the panel. Where
the outer surface of the radial flange portion includes
circumferentially spaced radial teeth, as described above, the
panel is deformed between the teeth, providing excellent torque
resistance.
[0008] The male fastener and panel assembly of this invention thus
includes a male fastener preferably formed of a high strength steel
as described, including a shank portion, a radial flange portion
integral with the shank portion having a diameter greater than the
shank portion and a tubular barrel portion coaxially aligned with
the shank portion having a tubular portion integral with the flange
portion and a generally radially outwardly extending distal end
portion spaced from the flange portion, generally perpendicular to
the tubular portion. The metal panel includes a planar portion
surrounding the outer surface of the flange portion and an L-shaped
portion including a portion extending perpendicular to the planar
portion having an inner surface deformed against the outer surface
of the radial flange portion preferably in substantially face to
face contact therewith and a radially inwardly directed portion
deformed between the radial flange portion and the generally
radially outwardly extending distal end portion of the barrel
portion. Where the outer surface of the radial flange portion
includes a plurality of circumferentially spaced radial teeth as
described above, the inner surface of the L-shaped panel portion is
deformed radially inwardly between the teeth substantially filling
the space between the teeth and provided improved toward
resistance. In fact, testing has established that the shank portion
will break before rotation of the stud relative to the panel.
[0009] In the disclosed embodiment, the radially inwardly extending
panel portion received between the generally radially outwardly
extending distal end portion of the barrel portion and the flange
portion is generally rectangular in shape having a width equal to
about one half the width of the planar panel portions surrounding
the radial flange portion. The inner surface of the tubular barrel
portion formed by the concave annular die surface is arcuate and
smoothly blends with the L-shaped panel portion providing a smooth
continuous arcuate surface extending from the bottom surface of the
radial flange portion to the outer distal end of the generally
radially outwardly extending distal end portion of the barrel
portion.
[0010] As set forth above, the self-riveting male fastener of this
invention is formed of a high strength carbon steel, preferably
having a hardness of greater than 30 Rockwell C or between 30 and
40 Rockwell C, for high performance applications, including safety
related applications. However, where the barrel portion of the male
fastener element has an axial length greater than about 60% of the
outer diameter of the outside diameter of the barrel portion and
the barrel portion is deformed into a U-shape as shown in the above
referenced U.S. Pat. No. 5,092,724, the barrel portion will crack
when formed of a high strength carbon steel having a hardness
greater than 30 Rockwell C. In the preferred embodiment, the axial
length of the barrel portion is about 55% of the outside diameter,
whereas the axial length of the male fastener disclosed in the
above referenced U.S. Pat. No. 5,092,724 is about 80% of the
outside diameter or greater.
[0011] Other advantages and meritorious features of the male
fastener and male fastener and panel assembly of this invention
will be more fully understood from the following description of the
preferred embodiments, the appended claims and the drawings, a
brief description of which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an elevated side view of one embodiment of the
self-riveting male fastener of this disclosure;
[0013] FIG. 2 is a side cross-sectional view of the male fastener
shown in FIG. 1;
[0014] FIG. 3 is a side view of the male fastener shown in FIGS. 1
and 2;
[0015] FIG. 4 is an end view of the male fastener shown in FIGS. 1
to 3;
[0016] FIG. 5 is a side view of a die button which may be utilized
in the installation of the male fastener shown in FIGS. 1 to 4 in a
panel;
[0017] FIG. 6 is a partial side cross-sectioned view of the die
button shown in FIG. 5 as indicated by the reference 6 in FIG.
5;
[0018] FIG. 7 is a partial cross-sectioned side view of an
installation apparatus, including the die button shown in FIGS. 5
and 6 for installing the male fastener shown in FIGS. 1 to 4 in a
panel;
[0019] FIG. 8 is a partially cross-sectioned side view of the
installation apparatus shown in FIG. 7 during installation of the
self-riveting male fastener;
[0020] FIG. 9 is a side partially cross-sectioned view of the male
fastener and installation apparatus shown in FIGS. 7 and 8
following installation of the male fastener in a panel; and
[0021] FIG. 10 is a side partially cross-sectioned view of the male
fastener and panel assembly of this invention following
installation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] As will be understood by those skilled in this art and
discussed further below, the drawings illustrate only one preferred
embodiment of the self-riveting male fastener and male fastener and
panel assembly of this invention for illustrative purposes only.
The embodiment of the self-riveting male fastener 20 illustrated in
FIGS. 1-4 includes a shank portion 22, which may be externally
threaded as shown at 24, a radial flange portion 26 integral with
the shank portion 22 having a diameter greater than the shank
portion 22 and a tubular barrel portion 28 integral with the radial
flange portion 26. As shown in FIG. 2, the tubular barrel portion
28 is coaxially aligned with the radial flange portion 26 and the
shank portion 22 relative to the longitudinal axis "A" of the
self-riveting male fastener 20.
[0023] The tubular barrel portion 28 preferably has a cylindrical
outer surface 30, a bottom wall 32 and a cylindrical inner surface
34, such that the tubular barrel portion has a substantially
constant cross-sectional area beginning with the bottom wall 32 to
adjacent the distal open end 40. In the disclosed embodiment, the
distal end 40 of the barrel portion 28 includes an arcuate outer
surface 36 and a chamfered inner surface 38. The tubular barrel
portion has an axial length "L" measured from the annular surface
42 of the radial flange portion 26 adjacent the tubular barrel
portion 28 and an outer diameter "D" of the cylindrical outer
surface 30. As set forth above, the dimensional relation between
the length "L" and the outer diameter "D" of the tubular barrel
portion 28 is critical to avoid cracking of the barrel portion
during installation in a panel in high performance applications
where the fastener element 20 is formed of a high strength hardened
carbon steel as required for such applications. In a preferred
embodiment, the axial length "L" of the tubular barrel is less than
60% of the outer diameter "D" or more preferably about 55%. The
self-riveting male fastener 20 is preferably formed of a high
strength carbon steel having a hardness greater than 30 Rockwell C
as discussed further below.
[0024] In such high performance applications, it is also desirable
to provide antirotation means or sufficient torque resistance to
prevent rotation of the fastener element 20 relative to a panel
following installation of the fastener element 20 in a panel. In
the disclosed embodiment of the self-riveting male fastener 20, the
outer surface of the radial flange portion 26 includes a plurality
of equally circumferentially spaced radial teeth 44 each having
generally radially extending planars side surfaces 48, a
cylindrical end surface 50 and planar surfaces 52 between the
radial teeth 44 as best shown in FIGS. 1 and 4. In a preferred
embodiment, the planar generally radially extending side surfaces
48 extend generally perpendicular to a circumference "C" of the
generally cylindrical radial flange portion 26 providing maximum
torque resistance when the radial flange portion 26 is driven into
a panel as described below. In the disclosed embodiment, the
generally radially extending planar side surfaces 48 of adjacent
radial teeth 44 are parallel for ease of manufacture. However, as
discussed further below, the radial teeth may have other
configurations or other antirotation means may be provided.
[0025] As described above, the self-riveting male fastener 20 may
be installed in a panel in a die press (not shown), wherein the
lower die shoe or die platen includes a die member or die button 54
as shown in FIGS. 5 and 6 and the upper die member includes an
installation head (not shown) having a reciprocating plunger
described below with regard to FIGS. 7 to 9. The die button 54
shown in FIGS. 5 and 6 includes a planar panel supporting surface
56 surrounding a die cavity 58 as best shown in FIG. 6. The die
cavity 58 includes an annular arcuate concave die surface 60 which
extends to adjacent the planar annular outer surface 56 and a
central die post 62 preferably having a planar end surface 64 and
an axial opening 66 to vent air from the die cavity 58 during
installation of the self-riveting male fastener 20 as shown in
FIGS. 7 to 9. The annular concave arcuate surface 60 preferably
blends with the planar panel-supporting surface with a slight
radius, as shown.
[0026] As disclosed further in the above referenced U.S. Pat. No.
4,915,558, the upper die shoe or die platen of a die press (not
shown) includes an installation head (not shown) which receives the
male fastener elements 20 and a reciprocating plunger 68 installs a
male fastener in a panel with each stroke of the die press. The
plunger 68 includes an axial opening 71 which receives the shank
portion 22 of the male fastener element 20 and an annular end face
74 which is driven against the radial flange portion 26 as shown in
FIG. 7. The panel 70 is supported on the annular panel supporting
surface 56 in the lower guide shoe (not shown) including a panel
preformed opening 72 having an internal diameter generally equal to
or slightly greater than the diameter of the outer cylindrical
surface 34 of the tubular barrel portion 28. The plunger 68 aligns
the tubular barrel portion 28 with the panel opening 72 and the
panel opening 72 is coaxially aligned with the die cavity 58, such
that the chamfered distal end surface 38 is coaxially aligned with
an inner surface of the annular arcuate concave die surface 60. The
annular end face 74 of the plunger 68 then drives the distal end 40
of the tubular barrel portion 28 through the panel opening 72 as
shown in FIG. 7. The plunger 68 then drives the distal end 40 of
the tubular barrel portion 28 against the annular arcuate concave
die surface 60, deforming the distal end 40 of the tubular barrel
portion radially outwardly in the annular arcuate concave die
surface 60 as shown in FIG. 8.
[0027] FIG. 9 illustrates the final step in forming the
self-riveting male fastener and panel assembly and FIG. 10 is an
enlarged view of the male fastener and panel assembly. As shown in
FIG. 9, the distal end 40 of the tubular barrel portion is deformed
radially outwardly into an L-shape, including generally radially
outwardly extending portion 74 spaced from the radial flange
portion 26 and a tubular portion 28A, including an arcuate surface
76 extending from the distal end 40 to the bottom wall 32 of the
barrel portion 28 which smoothly blends with the L-shaped panel
portion. As the annular surface 42 of the radial flange portion 26
is driven into the panel portion 70 surrounding the preformed
opening 72, a portion of the panel is deformed into the die cavity
58 (see FIG. 6) into an L-shape, including a portion extending
perpendicular to the planar panel and a generally radially inwardly
directed portion 78 deformed between the generally radially
outwardly directed barrel portion 74 and the annular surface 42 of
the radial flange portion 76. The L-shaped portion 78 further
includes an inner surface 80 which is deformed radially inwardly
against the cylindrical outer surface 50 of the radial teeth and
against the planar surfaces 52 between the teeth preventing
rotation of the self-riveting fastening element 20 and the panel
70. As best shown in FIG. 10, the radially inwardly directed panel
portion 78 is deformed between the annular surface 42 of the radial
flange 26 and the radially outwardly projecting distal end portion
74, such that the thickness of the radial portion 78 is about one
half the thickness of the original panel 70 and the inner panel
surface 80 is in substantially full face to face contact with the
outer surface of the radial flange portion 26.
[0028] Testing of the male fastener and panel assembly shown in
FIG. 10 results in a very secure installation and avoids cracking
of the barrel 28 even where the self-riveting male fastener element
20 is formed of a high strength carbon steel which has been heat
treated to a hardness of 30 Rockwell C or greater, making this
installation suitable for high performance applications including,
for example, automotive seat restraining studs and safety related
applications, such as seat and seat belt retainers, passive
restraints and the like. A suitable high strength carbon steel is
SAE 1038 carbon steel which is heat treated to Class 10.9,
resulting in a hardness of between 30 and 40 Rockwell C. The barrel
portion of a conventional 10 mm self-piercing stud as disclosed in
U.S. Pat. No. 5,092,724 has an axial length of 11 mm and an outside
diameter of 14 mm and an inside diameter of 10.3 mm, with a wall
thickness 1.85 mm, such that the volume of the barrel portion is
1,564.9 mm.sup.3. However, if the self-piercing stud shown in U.S.
Pat. No. 5,092,724 is heat treated to about 30 Rockwell C, the
barrel portion will crack if installed as disclosed in this patent.
In comparison, the barrel portion of a 10 mm stud as disclosed in
this application has an axial length of 6.8 mm, an outside diameter
of 12.55 mm and an inside diameter of 8.85 mm, resulting in a
volume of 834.8 mm.sup.3 and does not result in cracking of the
barrel when installed as shown in FIG. 10. Testing indicates that
the shank portion 22 will fracture before the stud is either
rotated in the panel or pulled out of the panel following
installation. The male fastener 20 may also be installed in
relatively thick panels, such as steel panels having a thickness of
3.5 mm. Thus, the self-riveting fastening element and panel
assembly of this invention may be utilized in high performance
applications and solves the problems associated with the prior
fastener systems for such applications.
[0029] As will be understood by those skilled in this art, various
modifications may be made to the self-riveting male fastener 20 and
fastener and panel assembly shown in FIG. 10 within the purview of
the appended claims. For example, the shank portion 22 may be
unthreaded for receipt of a thread-forming female fastener, such as
a nut or may have other configurations, including an integral ball
for utilization as a ball joint. Further, other antirotation means
may be utilized, such as the scalloped configuration shown in U.S.
Pat. No. 6,122,816, pockets or projections may also be provided in
the surface 42 of the flange portion as is known in this art.
However, equally circumferentially spaced radial teeth 44 having
generally radially extending planar side surfaces provides superior
torque resistance. Having described a preferred embodiment of the
self-riveting male fastener and male fastener and panel assembly of
this invention, the invention is now claimed as follows.
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