Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to an outwardly
expansible xivet nut, made integrally of one piece, and for
particular use on thin sheets.
There are different types of such rivet nuts now in
use, for use on thin sheets, which are characterized by their
methods of attachment to the sheets. There are some that can
be secured from either side of the sheet while others can only
be secured from one side. Among the latter are rivet nuts
formed by a hollow body having a threaded part at one end.
Referred to as one-side connecting elements, they can be
secured to the sheet from one side only and have, in addition
to known advantages, also a number of drawbacks.
One of these is that they can exist only in a very
narrow and positively restricted range of attachment. It is
further known in the art that any such connecting elements
which serve for connecting onto thin sheets is additionally
used, apart from its main purpose which is that of creating a
soli~ and reliable connection, to provide a bearing plate effect
that reinforces the thin sheet around the hole through which
the rivet nut extends. Known rivet nuts do not however
appropriately meet this requirement as the size of the rivet
head is substantially the same for thin or for thick sheets.
Known connecting elements wherein the part of the
body lying between the head the the threaded part is divided
longitudinally for affecting its integrity cannot be applied
where a closed connection is required.
A primary object of the present invention lies in the
provision of a rivet nut, for particular use with thin sheets,
providing a substantial reinforcement of the connection because
the closing head has a diameter which is much largex on the
inaccessible side of the sheet.
Accordingly, the present invention as herein broadly
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claimed is an outwardly expansible rivet nut of the a~ore-
mentioned type, comprising: a hollow body of substantially
constant outer diameter having a head at a front end to be
applied over one face of a sheet, this body having an expansible
part next to the head and a rigid part next to the expansible
part and away from the head, these parts being adapted to
extend through an opening in the sheet and away from the other
face thereof so as to provide a one-side connection; wherein the
expansible part of the body comprises a front section, next to
the head, having a front bore of which at least a portion has a
constant diameter and a central section having a central bore
of a diameter smaller than the constant diameter of the front
bore while the rigid part has an inwardly threaded bore adapted
for the screwing of a member after the mem~er has extended
through the front and middle bores, and a single circumferential
groove into the body from the outer surface and located in the
zone separating the expansible part and the rigid part.
Preferably, the front section extends along
substantially 2/3 of the expansible part while the middle
section extends along substantially the remaining 1/3 thereof.
Also, the groove may be about 1/2 of the thickness of the wall
of the central section.
Preferably also, means are provided to afford axial
reinforcement on at least part of the front section on its
outer surface.
An advantage of a one-sided rivet nut with axial
reinforcement is that of the combined effect of such axial
reinforcement o~ the ~ront section having a thinner wall and of
the annular groove on the outer surface of the body in the zone
that separates the central section and the threaded part. It
has been found that this effect provides a wide adaptability of
the one-sided connection for use on sheets having different
thicknesses, providing a high stress resistance of
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the closing~head. Another notable advantage of the invention
is that the closing head increases in size as the sheets get
thinner and where such a greater reinforcement is desired. For
thicker sheets, where the reinforcement effect of the closing
head is not as acutely required, the diameter of the closing
head may be smaller which, in turn, however gives an increased
reslstivity to stress by pull and torsion.
Preferred embodiments of the invention will now be
described with reference to the appended drawings whèrein:
Figure 1 is an elevation view of a rivet nut made
according to the invention with parts shown in longitudinal
cross-section;
Figure 2 is a cross-sectional view of Figure 1 taken
along line A-A thereof;
Figure 3 is a side elevation view intended to
illustrate the external surface of a rivet nut according to the
invention;
Figure 4 is a cross-sectional view taken along line
B-B of Figure 3;
Figure 5 is an elevation view of part of a rivet
according to the invention, also broken away to show the internal
structure, intended to illustrate another form of axial reinforce-
ment;
Figure 6 is a cross-sectional view taken along line
C-C of Figure S;
Figure 7 is a cross-section of a rivet nut made
according to the invention, shown applied onto a thin sheet with
part of an assembling tool and with the rivet being still in
the non-riveted condition;
Figure 8 is a side elevation view of the illustration
of Figure 7 with the rivet nut partially outwardly expanded;
Figure 9 is a side elevation view, partly shown in
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cross-section, illustrating the rivet nut in fully attached
condition onto a thin sheet, and
Figure 10 is a view similar to that of Figure 9 but
showing the rivet nut mounted onto a thicker sheet.
Referring now to the drawings, there is shown a hollow
inwardly threaded expansible rivet nut made according to the
invention and particularly adapted for connecting onto thin
sheets from one side thereof. This rivet nut comprises a hollow
body having a generally constant outer diameter and formed of
an expansible part 1 terminating at one end into a head 2 and
integrally continuing, at the other end, into a solid non-
expansible part 3 which has a threaded bore 4. The expansible
part 1 of the hollow body is made up of a front section 5,
bored as at 5a, and a central section 7, bored as at 7a, both
bores being of uniform diameter and bore 5a being greater than
bore 7a. The bore 5a preferably extends within 2/3 of the
length of the expansible part 1 and the wall thickness of
section 5 is relatively small while the bore 7a extends over
about the remaining 1/3 of the length of part 1 and the thick-
ness of the wall of middle section 7 is larger, this followingobviously from the fact that the outer diameter of the whole
rivet nut is substantially constant, as aforesaid. Likewise,
the diameter of the smaller bore 7a is preferably somewhat
larger than that of the threaded bore 4 in order to enable a
threaded member 10 (as in Figure 7) to be screwed thereinto
after extendirlg through bores 5a and 7a.
The outer surface of the rivet nut
is circular and provided, on the front section 5, with an
axial reinforcement 9 which may be in the form of ribs pro-
jecting from the outer surface of section 5, between the rivethead 2 and zone separating sections S and 7. These ribs are
evenly distributed about section 5, as shown. In the embodiment
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of Figures 5 and 6, the reinforcement 9 is in the form of
inwardly pressed axially extending and peripherally evenly dis-
tributed portions 8 of the wall o~ front section 5, leaving
therebetween reinforcement ribs 9a. The reinforcement 9 may
also be in the for~ of a polyhedron.
The outer surface of the rivet is provided, in the
zone separating sections 7 and 3, with an annular circumferential
groove 12 J the depth of which is about l/2 the thickness of the
wall of section 7.
The manner of securing the one-sided rivet nut into
an opening 13 of a thin sheet 14, as shown in Figures 7, 8 and
9, is obtained by screwing a threaded mandrel lO of an assembling
tool, from the accessible side of the opening 13, until a pres-
sure part ll is applied against the rivet head 2 thereby pres-
sing the latter into the opening 13. By drawing member lO
toward the sheet 14 (see arrows in Fig. 8), a sudden deformation
takes place in the transition zone between the bores 7 and 5
causing the expansible part l of the body to expand radially to
take the shape of two frusto-cones facing one another along
their large bases, as clearly shown in Figure 8. Further
drawing of the member lO, always from the inaccessible side of
the thin sheet 14, causes the thinner front section 5 to col-
lapse, as shown in Figure 9, while the thicker central section 7
retains its conical shape and presses onto the collapsed section
5 to apply it against the inaccessible face of the sheet 14.
With the aforesaid construction, it has been found that the
diameter of the closing head 5 in the thin sheet 14 is substan-
tially larger than that obtainable with rivet nuts of conventional
construction with the effect that a substantial increase is
obtained in the stress resistance to pull of the whole assembled
part.
The manner of securing a one~sided rivet nut into an
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opening 13 made in a thicker sheet 15 is the same as securing
it in a thin sheet 14, there being however a difference in
diameter of the formed closing head, which diameter is smaller
whereby the formed closing head shows a higher resistivity to
pull stresses. One will easily gather, from Figures 9 and 10,
the wide range of application of a one-sided rivet nut according
to the invention.
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