Note: Descriptions are shown in the official language in which they were submitted.
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I N TROD UCT IO N
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This invention relates to blind fasteners and more
particularly comprises a mandrel-type expandable anchor which
may be mounted in masonry, plaster, wood, metal, etc. The
anchor may be set in a wall of any thickness.
Mandrel-type fasteners are very well known. Most of
them, howeverl are only capable of being secured in a hole
through which it fully extends so that it may set like a
rivet behind the hole. The mandrel-type fastener of the
present invention is capable of being set in a hole in the
manner of a conventional rivet if it exceeds the hole length
or it may be anchored in a hole which is longer than the
anchor itself. Thu~, the anchor has a more universal
application than other mandrel-type fasteners now available.
In accordance with the present invention, the anchor is
composed of a body and a mandrel. The body is generally
; cylindrical in shape and is provided with a flange at its
front end, which serves as its head when the anchor is set in
a hole. A number of slits are provided in the body which
extend axially to the rear end of the body but terminate
; 20 short of the head at the front end. The mandrel carries a
head which extends out the rear of the body while the mandrel
stem extends through the body and out beyond the head so that
~; it may be engaged by a pulling tool for setting the anchor.Preferably the body of the anchor has a number of annular
barbs on its outer surface which can bite into the wall of
the hole in which the anchor is to be set. By pulling the
mandrel, the mandrel head enters the body which is allowed to
~xpand readily because of the slits, until the tension on the
mandrel causes it to break just forward of the mandrel head.
The anchor may be used to hang or otherwise secure any type
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of device to the wall or o1:her structure to which it is
connected.
The invention will be better understood and appreciated
from the following detailed description read in connection
with the accompanying drawings in which:
BRIEF FIGURE DESCRIPTION
FIG. 1 is a side view of a blind anchor constructed in
accordance with this invention;
FIG. 2 is a longitudinal cross-sectional view of the
anchor shown in FIG. l;
FIG. 3 is a cross sectional view of the anchor taken
along the section line 3-3 in FIG. iY;
FIG. 4 is a longitudinal cross-sectional view howing the
anchor set in a masonry wall;
FIG. 5 is a fragmentary cross-sectional view of the body
of another embodiment of anchor constructed in acccrdance
with this invention.
DETAILED DESCRIPTION
The anchor shown in FIGS. 1-4 includes a body l0 and
mandrel 12. The body may be made of metal, plastic or other
material and should be capable of deforming without
fracturing or shattering. In smaller sizes and lighter
applications particularly, the body may be made inexpensively
of a plastic material. Typically, the body may be
approximately l inch in length and its diameter may vary from
approximately 1/8 inch to 1~2 inchv again depending upon its
application. The body 10 is provided with a flange or head
14 at its front end having a diameter appreciably larger than
the diameter of the main part of the body so as to define a
3L~2Z~2~3
stop to limit the depth of penetration of the body in the
hole in which it i5 to be mounted. The head may be round,
polygon, or other shape, and it may be countersunk, flat, or
any other configuration determined by the particular
application~
In the embodiment of FIGS. 1-4, three longitudinally
extending slits 1~ are provided in the body 10 but a greater
or lesser number may be employed. The slits 16 extend to the
rear end 18 of the body and terminate at the front end short
of ~he flange 14. The slits 16 extend completely through the
walls so as to enable the body to deflect radially outwardly
when internal forces are applied to it. A plurality of
annular barbs 20 extend about the body 10 but are interrupted
by the slits 16. The barbs 20 are provided to bite into the
walls of the hole in which the anchor is mounted
Mandrel 12 which may be made of aluminum, steel or other
relatively hard and strong material, includes an elongated
stem 22, and on the rear end of the stem is a head 24. The
front end of the mandrel stem 22 extends outwardly beyond the
; flange 14 of the body while the head 24 of the mandrel
extends beyond its rear end 18. The diameter of the stem 22
is slightly less than the inner diameter of the body 10 so as
not to interfere with the pulling of the mandrel through the
body when the anchor is set. The head 24 merges smoothly
into the stem so that the diameter of its smaller end is
essentially equal to the stem diameter. The head diameter
increases in a rearward direction away from the body and,
therefore, the diameter at its outer end i~ appreciably
larger than the inner diameter of the body but no greater
than the outer diameter of the body. The rear end 18 of the
body at the head of the mandrel may be chamfered as shown in
FIG. 2 to lead the head 24 into the body when the anchor is
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set as described below. In the embodiment shown, a few
annular barbs 26 are provided on the head, but these are not
essential to the operation of the fastener. m e barbs may
serve to assist in holding the head 24 in the body when the
anchor is set, as is described more fully below.
In FIG. 2 it will be noted that the diameter of the stem
22 immediately adjacent the head 24 is reduced by a groove or
notch 30 which may extend about the stem~ The groove 30
provides a weakened section in the mandrel which will cause
the mandrel to break at that point when a sufficient tension
force is applied to it.
A typical application of the anchor is shown in FIG. 4.
In that figure a masonry wall 32 is shown provided with a
drilled hole 34 which exceeds the length of the anchor body
m e anchor is shown in that figure to support a
hook-like member 36 which is exemplary of the type of device
which may be secured to the wall 32 by the anchorO m e
member 36 is provided with a hole 38 which just exceeds the
outer diameter of the body 10 but which is smaller than the
diameter of the flange 14. To mount the member 36 as shown,
the body 10 is inserted through the hole 38 in the member 36
and then into the hole 34 bored in the masonry. The anchor
including the mandrel 12 and body 10 are in the configuration
shown in FIG. 2 when the anchor is inserted in hole 34. With
the use of a tool for setting blind fasteners, the portion of
the stem 22 of the mandrel which extends beyond the flange 14
is engaged and pulled to the right as viewed in FIG. 4 so as
to cause the body 10 to spread as the head 2~ of the mandrel
is pulled inside the body. The slits 16 enable the body 10
to expand under the influence of the head 24 being pulled
into it. As the body spreads, the circular barbs 20 bite
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into the margins of the hole 34. The head 24 continues to
move inside the body 10 until the stem of the mandrel
fractures at the groove 30~ When that occurs, the mandrel
stem is pulled from the body and the head 24 is left in place
as shown~ The compressible nature of the masonry material in
wall 32 allows the body to expand as shown in FIG. 4. It
will be appreciated that with the body expanded in that
fashion, and with the head 24 in place in the body~ the
anchor is ~ecure, and the member 36 will be retained on the
wall. In FIG. 4 the open end of the body through the head or
flange 14 is shown filled by a plug 40 which will prevent
foreign material of any kind from entering the wall. The
plug 40 is, of course, not essential to the operation of the
anchor but it or some form of cap to close the body may be
desirable for functional or aesthetic reasons.
While the anchor shown in FIG. 4 is permanently in place,
it will be appreciated that the anchor may be removed if the
head 24 is punched out the rear of the body. If the head 24
with the aid of a nail or other projection i5 driven
rearwardly out of body 10, the deformable character of the
body will enable it to be pulled from hole 34 in the masonry
wall with an appropriate tool. The slits 16 in the body will
allow the body to collapse to a diameter even smaller than
its orignal diameter in the absence of the mandrel or other
implement in the body interior.
While in the foregoing description the anchor is
described as being set in a hole which exceeds the length of
the anchor body, it will be appreciated that the same anchor
may be used in a wall whose thickness is less than the body
length. For that purpose, broken line S0 is provided in FIGo
4 to suggest that the depth of wall 32 is limited to the
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plane represented by line 50. In that instance, when the
body 10 is set in the hole drilled in the wal~, the rear end
of the anchor extends out beyond the rear surface 50 of the
wall. Nevertheless, by pulling the head 24 of the mandrel
into the body in the manner shown in FIG. 4, the body will
expand behind the rear surface 50, and when the mandrel
breaks at groove 30, the anchor will serve as a blind rivet
to support the member 36 on the front surface of the wall.
Thus it will be appreciated that the anchor may be used in
walls having an infinite range of thicknesses . The slits
allow the body to be spread to a point very close to the
flange 14, and the manner in which the body spreads under the
influence of the mandrel head 24 will be determined by ~he
size and material of the wall in which it is set.
In FIG. 5 a modification of the anchor body is
suggested. In the embodiment of FIGS. 1-4 the slits 16
extend completely through the body wall and essentially form
the body into a plurality of parallel leaves that extend
rearwardly from the head end of the body~ It may be
desirable in certai.n applications, such as when the body is
molded of plastic, to leave a very thin portion of the wall
at the slit in tact to give the body greater integrity than
it would otherwise be afforded. In this embodiment the slit
16a is shown to extend through the barb 20a and most of the
body wall cross-section, but it terminates just short of the
inner surface 60. Alternatively, the slit may terminate just
short of the outer surface or the outer margin of the barbs.
As yet another alternative~ the slits could extend completely
through the body but terminate just short of the rear end
18~ A great number of different arrangements may be used,
all of which would allow the slits to open f~lly when the
mandrel head is drawn i~ ~ ~e ~ody but which would hold the
body's shape when the mandrel is in place but before it is
drawn into it. That is, the head of the mandrel would
fracture the slits to allow the body to expand as the anchor
is set.
Having described this invention in detail, those skilled
in the art will appreciate that numerous modifications may be
made thereof without departing from its spirit. Therefore,
it is not intended to limit the breadth of this invention to
the single embodiment illustrated and described. Rather, it
is intended that the scope of this invention be determined by
the appended claims and their equivalents.
What is claimed is:
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