Note: Descriptions are shown in the official language in which they were submitted.
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ANCHOR FOR HOLLOW WALLS
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wall anchors and, more particularly, to
self drilling anchors for use typically in hollow walls made of friable
materials, e.g.
plasterboard, gypsum, etc.
2. Description of the Prior Art
The Ernst et al, Gianuzzi and McSherry U.S. Patents Nos. 4,601,625,
5,234,299 and 5,529,449, respectively, each disclose an anchor which is turned
in a
wall made of friable material and is retained in the wall by virtue of the
friable
material being compressed between the root and deep thread spiraled along the
cylindrical body of the anchor and between the proximal end of the thread and
flanged
end of the anchor which becomes embedded in the front surface of the wall. A
work
piece is then fastened to the wall by a screw fastener that is screwed into
the visible
open end of the anchor and holds the workpiece between the flanged end of the
anchor and the head of the screw fastener.
Toggle bolts are also known, such as in U.S. Patent No. 6,435,789
issued on August 20, 2002 to Gaudron. Generally a self drilling toggle anchor
includes a drilling member and a toggle member. The drilling member is adapted
to
drill through the wall hole with the toggle member in its retracted position,
i.e.
extending axially along the drilling member, whereby the whole anchor is
inserted
longitudinally in the wall with the toggle member being located completely
behind the
wall. The toggle member defines a threaded opening that extends transversally
therethrough and that has, in the retracted position of the toggle member, its
axis
perpendicular to the drilling member and to the longitudinal orientation of
the whole
anchor when it drilled into the wall. In a second step, a screw is rotatably
inserted in
the anchor ands at one point, a tip of the screw engages-the toggle-member and
causes
it to pivot an extended position thereof, wherein the toggle member extends at
right
angles to the drilling member and to the general orientation of the anchor.
The screw
then engages the threaded opening of the toggle member. Once the head of the
screw
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abuts the front of the wall or the head of the anchor, it cannot displace
longitudinally,
such that further rotation of the screw draws the toggle member
translationally
towards the head of the screw and thus towards the rear face of the wall until
is abuts
firmly the same, whereby the anchor is fixed to the wall. Alternatively, the
drilling tip
can be provided on the toggle member, and in such cases the above drilling
member
remains similar in that it fixedly depends from the anchor head but it does
not perform
the drilling action. Such designs are somewhat costly, as the anchor requires
two
distinct components (e.g. the above drilling and toggle members) that also
must be
assembled together.
SUMMARY OF THE INVENTION
It is therefore an aim of the present invention to provide an improved
anchor adapted to be securely mounted to a hollow wall such that an item can
be
attached thereto, e.g. via an elongated fastener engaged in the anchor.
Therefore, in accordance with the present invention, there is provided
an anchor for mounting to a hollow wall, comprising a proximal end adapted to
be
engaged by a rotatable tool to rotate said anchor about a longitudinal axis
thereof and
to cause it to gradually engage a wall, a distal end adapted to cut through
the wall as
said anchor is rotated, and a shank between said proximal and distal ends,
said shank
including at least one expandable leg, said expandable leg being in a
collapsed
position thereof when said anchor is rotated to mount it to the wall and being
located
distally past a rear surface of the wall once said anchor is mounted to the
wall, said
anchor including outer threads, said anchor being adapted to receive therein a
threaded fastener and to threadably engage the same distally of said leg such
that
sufficient rotation of the threaded fastener retracts said distal end towards
said
proximal end thereby causing said leg to displace to a laterally expanded
position
thereof.
Also .in accordance with the present invention,- there is provided an
anchor assembly for mounting to a hollow wall, comprising a threaded fastener
and an
anchor; said anchor including a proximal end adapted to be engaged by a
rotatable
tool to rotate said anchor about a longitudinal axis thereof and to cause it
to gradually
engage a wall, a distal end adapted to cut through the wall as said anchor is
rotated,
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and a shank between said proximal and distal ends, said shank including at
least,one
expandable leg, said expandable leg being in a collapsed position thereof when
said
anchor is rotated to mount it to the wall and being located distally past a
rear surface
of the wall once said anchor is mounted to the wall, said anchor including
outer
threads, said anchor being adapted to receive therein said threaded fastener
and to
threadably engage the same distally of said leg such that sufficient rotation
of said
threaded fastener retracts said distal end towards said proximal end thereby
causing
said leg to displace to a laterally expanded position thereof
Further in accordance with the present invention, there is provided an
anchor for mounting to a hollow wall, comprising a proximal end adapted to be
engaged by a rotatable tool to rotate said anchor about a longitudinal axis
thereof and
to cause it to gradually engage a wall, a distal end and a shank between said
proximal
and distal ends, said shank including at least one expandable means, said
expandable
means being in a collapsed position thereof when said anchor is rotated to
mount °it to
the wall, said anchor including outer threads, said anchor being adapted to
receive
therein a threaded fastener and to threadably engage the same distally of said
expandable means such that sufficient rotation of the threaded fastener
retracts said
distal end towards said proximal end thereby causing said expandable means to
displace to a laterally expanded position thereof behind the wall.
Still further in accordance with the present invention, there is provided
a method for mounting an anchor to a hollow wall, comprising the steps of:
a) providing a hollow anchor including outer threads and having a
proximal end, a distal end and a shank between said proximal and distal ends;
b) installing said anchor in a wall; and
c) rotatably driving a threaded fastener in said anchor such that said
threaded fastener engages distal end and causes, once said fastener cannot
further
advance translationally in said anchor, said distal end to retract towards
said proximal
end thereby deforming said shank such that said shank laterally expands behind
the
wall.
Still further in accordance with the present invention, there is provided
a method for forming inner threads in a hollow anchor adapted for a hollow
wall,
comprising the steps of:
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a) providing a core pin having outside threads thereon;
b) molding an anchor in a mold with said core pin therein such that
said core pin is at least partly surrounded by plastic; and
c) translationally removing said core pin, without substantially rotating
it, from the molded anchor without stripping the female threads formed by said
core
pin in said anchor.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus generally described the nature of the invention, reference
will now be made to the accompanying drawings, showing by way of illustration
a
preferred embodiment thereof, and in which:
'Fig. 1 is a schematic side view, partly in cross section, showing a first
wall anchor in accordance with the present invention, engaged into a wall and
in a
collapsed position thereof;
,Fig. la is an end view of the wall anchor of Fig. 1;
Figs. lb and lc are end views of variants of the wall anchor of Figs. 1
and 1 a;
Fig. 2 is a schematic side view, partly in cross section, that is similar to
Fig. 1, but shows the wall anchor of Fig. 1 in an expanded position thereof;
Fig. 2a is an end view of the wall anchor of Fig. 2;
Figs. 2b and 2c show the variants of Figs. lb and lc in the second
position of the wall anchor;
Fig. 3 is a schematic side view, partly in cross section, of a second wall
anchor in accordance with the present invention, which is similar to Fig. 1
and which
is shown in a collapsed position thereof;
Figs: 3a to 3c are similar to Figs. la to lc, but pertain to the wall
anchor of Fig. 3;
Figs. 4 and 4a to 4c _are similar to Figs. 2 and 2a to 2c, but pertain to
the second wall anchor of Fig. 3 that is shown in an expanded position
thereof;
Fig. 5 is a schematic side view, partly in cross section, of a third wall
anchor in accordance with the present invention, shown in a collapsed position
thereof;
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Fig. Sa is an end view of the wall anchor of Fig. 5;
Fig. 6 is a schematic side view, partly in cross section, of the wall
anchor of Fig. 5, but showing the wall anchor in an expanded position thereof;
Fig. 6a is an end view of the wall anchor of Fig. 6;
5 Figs. 7 and 7a to 7c are similar to Figs. 1 and 1 a to 1 c, but show a
fourth wall anchor in accordance with the present invention and in a collapsed
position thereof, with Fig. 7 being a cross-sectional view;
Figs. 8 and 8a to 8c are similar to Figs. 2 and 2a to 2c, but pertain to
the wall anchor of Fig. 7 that is shown in an expanded position thereof, with
Fig. 7
being a cross-sectional view;
Figs. 9 and 9a to 9c are similar to Figs. 1 and la and lc, but show a
fifth wall anchor in accordance with the present invention and in a collapsed
position
thereof;
Figs. 10 and l0a to lOc are similar to Figs. 2 and 2a to 2c, but pertain
to the wall anchor of Fig. 9 that is shown in an expanded position thereof;
Fig. 11 is a schematic side view, partly in cross section, of a sixth wall
anchor in accordance with the present invention, shown in a collapsed position
thereof;
Fig. 12 is a view similar to Fig. 11, but shows the sixth wall anchor in
an expanded position thereof;
Fig. 13 is a side view, partly in cross section, that is similar to Fig. l,
but shows a seventh wall anchor in accordance with the present invention and
in a
collapsed position thereof;
Fig. 14 is a side view, partly in cross section, of the wall anchor of Fig.
13, but in an expanded position thereof;
Fig. 15 is a side view, partly in cross section, of an eighth wall anchor
in accordance with the present invention, shown in a collapsed position
thereof;
Fig. 16 is a side view, partly in cross section, of the ~wall anchor of Fig.
15, but shown in an expanded position thereof;
Fig. 17 is a side view of an anchor section of the wall anchor of Fig.
15;
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Fig. 18 is a side view of a locking member of the wall anchor of Fig.
15;
Fig. 19 is a schematic side view of a ninth wall anchor in accordance
with the present invention, also shown being a molding pin used in the
manufacture of
the ninth anchor;
Fig. 20 is an end view of the wall anchor of Fig. 19;
Fig. 21 is a cross-sectional view of the wall anchor of Fig. 19;
Fig. 22 is a side view of a tenth wall anchor, similar to that of Fig. 3,
and also in accordance with the present invention;
Fig. 23 is an end view of the tenth anchor of Fig. 22; .
Figs. 24, 25 and 26 are cross-sectional views taken respectively along
lines 24-24, 25-25 and 26-26 of Fig. 22;
Figs. 27a to 27d are successive partly cross-sectional side views
showing the installation of the tenth anchor of Fig. 23 into a wall;
Figs. 28 and 29 are respectively a side view and a longitudinal cross-
sectional view of the tenth anchor of Fig. 23 provided with a core pin therein
.that is
used during the molding thereof;
Figs. 30 and 31 are respectively a side view and a partly cross-sectional
view of part of the core pin.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with the present invention, Fig. 1 illustrates a wall
anchor 10 in its first, i.e. insertion, position, with Fig. 1 showing the wall
anchor 10
fully inserted through a wall W and with a screw S engaged in the wall anchor
10 and
holding an item I against the wall W. In Fig. 2, the wall anchor 10 is shown
in a
second, i.e. expanded, position thereof wherein the wall anchor 10 is further
secured
to the wall W, as explained in details hereinafter. The wall anchors described
herein
are generally all made of plastics material, e.g. nylon.
The wall anchor 10 is hollow, for receiving the screw S therein, and
comprises a pointed distal tip 12 provided with a partial thread 14
therearound and
defining an opening 16. Proximally, the wall anchor 10 includes a head 18 and,
between the head 18 and the distal tip 12, the wall anchor 10 comprises a
shank 20.
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The proximal portion of the shank 20 includes a thread 22 and, between the
threads 14
and 22, the shank 20 includes a system of expandable legs 24. In the
embodiment
shown in Figs. 1 and 2, the shank 20 includes four such legs 24 which, in the
collapsed position of Fig. 1, are linked together by frangible films 26,
although such
films can be absent, in which case the legs 24 extend along side each other
but are not
connected together.
The head 18 can be engaged by a torque driven rotational tool, such as
a screwdriver, manual or powered. For instance, the head 18 can define a
cruciform
recess (see reference 819 in Fig. 20 and 919 in Fig. 23) for receiving a
Phillips-type
screwdriver bit. This allows the wall anchor 10 to be rotatably driven, as a
screw,
through the wall W, with the distal tip 12 assisting in penetrating the wall
10 and with
the threads 14 and 22 consecutively engaging the friable material of the wall
W and,
in fact, tapping the same such that the wall anchor 10 is secured to the wall
by way of
the threads 22. The opening 16 assists in evacuating the friable material that
has been
removed from the wall W by the wall anchor 10. Once the wall anchor 10 is in
its
position shown in Fig. 1 with respect to the wall W, the screw S, with or
without the
item I located between the head of the screw S and the front or visible
surface of the
wall W, is rotatably engaged into the wall anchor 10 until it assumes its
position
shown in Fig. 1.
Once the head of the screw S cannot further axially translationally
advance (in Fig. 1 because of its abutment with the item I, or alternatively
because it
has engaged the head 18, or even the visible surface of the wall W), further
rotation of
the screw. S causes the distal tip 12 of the wall anchor 10 to be pulled
towards the wall
W in view of the threaded engagement between the screw S and the wall anchor
10,
typically at section 28 thereof that has been tapped by the screw S (although
female
threads may alternatively have been formed by molding within the section 28).
The
gradual retraction of the distal tip 12 towards the head 18 causes the legs 24
to
outwardly expand and, initially, any frangible filin 26. between.
adjacent.legs 24 is
ruptured.
Each leg 24 has a shorter proximal portion 30 and a longer distal
portion 32 that connect at pivot 33. The expansion of the legs 24 is
interrupted by the
proximal leg portions 30 abutting the rear or non-visible surface of the wall
W, as
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seen in Fig. 2, in which position the proximal and distal leg portions 30 and
32 form
with the screw S a substantially right angled triangle.
Additionally, the shank 20, for instance inwardly of (i.e. within) the
legs 24, may include a stopper which, for example, extends around the screw S
and
which extends rearwardly from a proximal end of the distal tip 12 (examples of
stoppers are shown at 234 and 334 of the further embodiments of Figs. 5 and 6
and
Figs. 7 and ~, respectively). Such a stopper does not extend the full length
of the legs
24 when they are in their collapsed position of Fig. 1, such that a proximal
end of the
stopper engages, in Fig. 2, the non-visible surface of the wall W inwardly of
the
proximal leg portions 30 of the legs 24 andlor the inner ends of the proximal
leg
portions 30, thereby significantly impeding farther retraction of the distal
tip 12
towards the wall W. Even though the proximal leg portions 30, when they engage
the
non-visible surface of the wall W, offer resistance to such a further
retraction of the
distal tip 12, over-rotation of the screw S could cause the proximal leg
portions 30 to
dig into the wall W. With the stopper, which is of a length which
substantially
correspond to the third side of the right angled triangle that has the
proximal and
distal leg portions 30 and 32 as its two other sides, it is ensured that the
end position
of the wall anchor 10 will be that illustrated in Fig. 2. In other words, the
proximal
leg portions 30 and/or the stopper will substantially prevent the screw S from
being
over-rotated.
Figs. lb, 2b, lc and 2c show alternate shanks which, instead of having
four legs 24 as in Figs. 1 and 2, have five and three such legs, respectively.
Other
numbers of legs can also be contemplated.
Figs. 3 and 4 illustrate a second wall anchor 110, also in accordance
with the present invention, which is similar to the first wall anchor 10,
except that a
shank 120 of the wall anchor 110 includes a thread 121 therearound that is
substantially continuous with the threads 114 and 122. Also, in the wall
anchor 110,
the proximal and distal leg portions 130 and 132.-of he legs 124 thereof are
of a same
length such that they assume the general flattened end position shown in Fig.
4, with
the threads 121 of the proximal leg portion 130 engaging the non-visible
surface of
the wall W. In Figs. 3 and 4, the screw S that is illustrated has a larger
pitch wood-
type thread that makes the installation of the screw S (including the
expansion of the
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__ _ . _
wall anchor 110) faster, i.e. with less rotations being required from the
screw S. As
for the first wall anchor 10, the second wall anchor 110 includes a distal tip
112, an
opening 116, a head 118 and a tapped section 128, and can also include
frangible
films 126, such as frangible films 26 of the first wall anchor 10.
_ Figs. 3b, 4b, 3c and 4c show variations of the wall anchor 110, i.e. with
five and three legs instead of the four legs 124 shown in Figs. 3 and 4.
As a variant to the second wall anchor 110 (and possibly also to other
wall anchors, e.g. to the first wall anchor 10), the section 128 of the shank
120 can
include a metal insert provided with inner threads (i.e. it does not need to
be tapped by
the screw S) and mounted, for instance molded, into the plastic shank 120 of
the wall
anchor 110, the inner threads of such a metal insert (which acts as a nut)
being
typically adapted to receive a machine screw.
Figs. 5 and 6 illustrate a third wall anchor 210, which is somewhat
similar to the first wall anchor 10, except that it includes only two,
diametrically
opposed, legs 224. A pair of stoppers 234 are part of the shank 220 and extend
between the legs 24 and rearwardly from a proximal end of the distal tip 212.
The
proximal ends of the stoppers 234 are adapted to limit the retraction of the
distal tip
212 towards the head 218 such that the wall anchor 210 assumes, in its final
position,
the general configuration shown in Fig. 6.
The wall anchor 210 further includes a distal thread 214, a distal
opening 216, a proximal thread 222, a tapped section 228 and proximal and
distal leg
portions 230 and 232.
Figs. 7 and 8 illustrate a fourth wall anchor 310 in which a stopper 334
takes the form of a cylinder that extends rearwardly from the distal tip 312
and within
the legs 324. The stopper 334 can take the form, as illustrated, of a rearward
extension of the tapped section 328 such that it is also tapped by the screw
S. The
number of legs 324 in the shank 320 can vary, as seen for instance in Figs. 7a
and 8a,
__ 7b_and 8b, and 7c and 8c where four, five and three legs are illustrated
respectively.
The fourth wall anchor 310 also includes a distal thread 314, a distal
opening 316, a proximal head 318, a proximal thread 322 and proximal and
distal leg
portions 330 and 332. Frangible sections can also be provided between adjacent
legs
324, as in the first wall anchor 10 of Figs. 1 and 2.
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Figs. 9 and 10 illustrate a fifth wall anchor 410 also in accordance with
the present invention, which is similar to the first wall anchor 10 of Figs. 1
and 2, but
which shows a variant distal tip 412 that is based on the distal section of
the self
drilling anchor of aforementioned U.S. Patent No. 5,234,299. The distal tip
412 of
5 the wall anchor 410 could also take the shape of the blade of the self
drilling threaded
insert of aforementioned U.S. Patent No. 4,601,625. In fact, these variant
distal tips as
well as others can be contemplated for the various wall anchors disclosed
herein.
With the illustrated distal tip 412, the wall anchor 410 is initially
punched through the wall W before being rotated such that the proximal threads
422
10 thereof engage the wall W. The wall anchor 410 also includes a head 418, a
shank
420, legs 424, frangible films 426, a tapped section 428 and proximal and
distal leg
portions 430 and 432.
Figs. 9a and l0a show the shank 420 having four legs 424 as in Figs. 9
and 10, whereas Figs. 9b, lOb, 9c and l Oc show alternate leg configurations
consisting
of five and three legs 424.
In Figs. 11 and 12, a sixth wall anchor 510 is shown, wherein a shank
520 includes side-by-side legs 524 which are slightly angled with respect to a
longitudinal axis of the wall anchor 510 and in a direction that is opposite
the torque
exerted when the wall anchor S 10 is rotatably inserted in the wall W in order
to
provide added rigidity to the shank 520 during the rotary installation of the
wall
anchor 510. The legs 524 are detachably connected together by way of frangible
portions 526 which, as in previous embodiments, provide additional rigidity to
the
shank when compared to legs that are not initially connected together. The
shank 520,
as the shank 120 of Figs. 3 and 4, includes a thread 521 that provides with
the
proximal thread 522 and the distal thread 514 a substantially continuous
thread. Once
expanded, as seen in Fig. 12, the wall anchor 510 defines a bundle that is in
abutment
with the non-visible surface of the wall W, this bundle being formed by the
deformed
legs 524. _ _. _ _
The sixth wall anchor 510 also includes a distal tip 512, a distal
opening 516, a proximal head 518 and a tapped section 528.
Figs. 13 and 14 show a seventh wall anchor 610 in accordance with the
present invention, which is similar to the first wall anchor 10, except that
two of its
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legs 624 expand inwardly, such legs being designated by reference numerals 634
in
Figs. 13 and 14. These inwardly deflecting 'legs 634 act as a stopper to
resist further
retraction of the distal tip 612 towards the wall W once the wall anchor 610
has
generally assumed its second position shown in Fig. 14.
The wall anchor 610 also includes a distal thread 614, a distal opening
616, a head 618, a shank 620, a proximal thread 622, frangible films 626, a
tapped
section 628 and proximal and distal leg portions 630 and 632.
Figs. 15 and 16 show an eighth wall anchor 710 in accordance with the
present invention that consists of two separate components and, more
particularly, of
a threaded anchor section 711 (shown in isolation in Fig. 17) and an
expandable
locking member 724 (shown in isolation in Fig. 18). The anchor section 711
includes
a distal tip 712, a distal thread 714, a distal opening 716, a proximal head
718, a shank
720, and a proximal thread 722.
The locking member 724 is initially collapsed, as seen in Fig. 15, being
partly received in longitudinal grooves defined on diametrically opposed sides
of the
shank 720. The locking member 724 defines a pair of notches 726 that are
adapted to
engage a proximal end of the shank 720, when the locking member 724 is
collapsed,
wherein tips 728 defined by the notches 726 are held inwardly of the shank
720. The
locking member 724 also includes a distal cylindrical member 730 that can be
tapped
by the screw S.
Once the screw S has been sufficiently inserted in the anchor section
711, it contacts the locking member 724 and displaces it axially away from the
head
718 thereby disengaging the tips 728 of the locking member 724 from the shank
720
of the anchor section 711. As the locking member 724 is spring loaded, its
release
from the shank 720 causes it to automatically deploy to its position shown in
Fig. 18.
The cylindrical member 730 of the locking member 724 is then tapped by the
screw S
and with subsequent rotation of the screw S, the locking member 724 is
retracted
towards the wall W until it assumes the position_shown in Fig. l6. In facts
the locking
member 724 basically acts as a toggle that is displaced between a collapsed
idle
insertion position (Fig. 15) and a wall engaging expanded position (Fig. 16).
The locking member 724 is inserted by the manufacturer of the wall
anchor 710 through the central bore of the anchor section 711, from the head
718
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towards the distal tip 712, that is until the collapsed locking member 724
extends
partly in the longitudinal grooves of the shank 720 while the tips 728 of the
locking
member 724 are prevented from expanding by the proximal end of the shank 722.
Again, once the screw S has been sufficiently inserted, it axially moves the
locking
member 724 along the bore of the anchor section 711 until the tips 728 are
disengaged
from the shank 720 and are spring biased exteriorly through the longitudinal
grooves
of the shank 720.
Figs. 19 and 20 illustrate a ninth wall anchor 810 in accordance with
the present invention, which is characterized by having inside threads 828
defined in
the distal end of the shank 820 and, interruptingly, in the open distal end
812. The
threads 828 defined in the shank 820 are continuous, but the inside threads
828
defined in the distal tip 812 are interrupted by the distal opening 816. The
inside
threads 828 of the wall anchor 810 are obviously adapted to be~engaged by the
outside
threads of the screw S (not illustrated). This configuration provides more
threads in
the wall anchor 810 that can be engaged by the threads of the screw S thereby
providing more strength at the level of the engagement of the screw S with the
wall
anchor 810, which thus prevents stripping of the threads 828 of wall anchor
810 when
the screw S is further rotated in order to retract the distal tip 812
rearwardly towards
the wall for expanding the legs 824 provided on the shank 820.
A pin P is located in the anchor 810 and is used during the molding
process to define the female inside threads 128. The structure of this pin P
and how it
is used will be described in details hereinafter.
The wall anchor 810 also includes a distal thread 814, a proximal head
818, a proximal thread 822, and a thread 821 around the legs 824 so as to
provide,
with the threads 814 and 822, a continuous outside male thread (although
interrupted
at the distal opening 816). A tube 834 is provided in the shank 820 of the
wall anchor
810 to provide more rigidity when the wall anchor 810 is installed in the
wall.
Figs. 22 to -26 -show a -tenth wall anchor 910 in accordance with he
present invention, which is similar to that of Fig. 3 although the wall anchor
910
includes an inner thread 928 (as in Fig. 19) located interruptingly inside the
distal tip
912 and un-interrruptingly within a cylindrical section 936 that extends
axially
between a distal end of the shank 920 and a proximal end of the distal tip
912. This
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inner thread 928 is adapted to be engaged by the thread of the screw S upon
rotation
thereof, and once the screw S is prevented from further advancing into the
anchor 910
(e.g. because it has abutted item I or the head 918 of the anchor 910),
further rotation
of the screw S causes the distal tip 912 to be axially and translationally
drawn towards
the head 918 thereby causing the deformation (i.e. outward expansion) of the
legs 92A.
onto the hidden face of the wall W. A longitudinal axis of the anchor 910 is
denoted
by "A", and such an axis characterizes each of the anchors described herein.
The provision of female threads 128 both in the cylindrical section 936
and in the distal tip 912 increases the overall female thread length that can
be engaged
by the threads of the screw S thereby providing more strength at the level of
the
engagement of the screw S with the wall anchor 910, which thus prevents
stripping of
the threads 928 of wall anchor 910 when the screw S is further rotated in
order to
retract the distal tip 912 rearwardly towards the wall for expanding the legs
924
provided on the shank 920.
Figs. 27a to 27d illustrate the installation sequence of the present
anchors and will now be described with reference to the tenth wall anchor 910.
As
seen in Fig. 27a, the wall anchor 910 is positioned with its distal tip 12
against the
visible side of the wall W, and it is rotatably engaged therein using an
appropriate
torque-inducing tool, such as a screwdriver, having a bit formed to fit in the
recess
defined in the head 918 of the anchor 910. Here, a Phillips-type screwdriver
bit B is
used to fit into the cruciform recess 919. The anchor 910 is rotated until its
head 918
abuts the visible side of the wall W, as seen in Fig. 27b. The screw S is then
rotatably
engaged in the wall anchor 910 using the screwdriver bit B and the screw
translationally advance into the wall W until it reaches its position shown in
Fig. 3,
whereat it is prevented from further advancing by the item I firmly abutting
the wall
W. As explained above and as seen in Fig. 27c, subsequent further rotation of
the
screw S causes, in view of the male threads of the screw S being engaged with
the
female threads 928, of the anchor 910, the distal tip 912- to be axially and-
translationally drawn towards the head 918, thereby causing the deformation
(i.e.
outward expansion) of the legs 924 onto the hidden face of the wall W and
firmly
securing the anchor 910 to the wall W. As seen in Fig. 27d, such a deformation
results
SUBSTITUTE SHEET (RULE 26)
CA 02509379 2005-06-09
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in some of the threads 921, provided around the arms 924, engaging (e.g.
piercing
into) the hidden face of the wall W.
Figs. 28 and 29 illustrate the tenth anchor 912 of Fig. 23 with a core
pin P therein that is used during the molding thereof to form the through
passage
extending axially through the anchor 910, including the inner threads 928
thereof.
More particularly, the core pin P includes a main pin section 1000 (also shown
in
isolation in Figs. 30 and 31) that has a first portion 1002 adapted to form
the inside of
the head 918, of the expandable legs 924 and of the part of the shank 920 that
extends
between the head 918 and the expandable legs 924, and a second portion 1004
adapted to form the female threads 128 of the cylindrical section 936. The
core pin P
also includes a secondary pin section 1006 that is adapted to form the threads
928
located in the distal tip 912 of the anchor 910. A distal end 1008 of the
second portion
1004 of the main pin section 1000 is shaped so as to mate with a proximal end
IOIO
of the secondary pin section 1006, and this ensures the alignment of the main
pin
section 1000 and the secondary pin section 1006, and thus a female thread 128
that is
substantially uninterrupted at a junction of where it was formed by the main
pin
section 1000 and where it was formed by the secondary pin section 1006, and
that has
a constant pitch.
The mold also includes two outer mold sections that will provide the
shape to the outside of the anchor 910, and once the plastic has been injected
in the
mold, the main pin section 1000 is pulled out axially and translationally from
the
mold, while the secondary pin section 1006 is removed laterally from the
distal end
912, i.e. through the opening 916 thereof. It is noted that the main pin
section 1000 is
pulled out from the mold during a specified period after the injection
process, such
that the main pin section 1000 does not strip the female threads 128 that is
has
molded, these female threads completely solidifying after the main pin section
1000
has been so removed. In the prior techniques, the pin would be rotatably
removed
from the molded anchor, which is much more time ,consuming than ,the ,present
translational withdrawal thereof.
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