Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a panel anchor of the type by
means of which a screw may be secured to a panel. The
invention will be described with particular reference to
securing a screw to a panel but it will be understood also
to be applicable for securing a bolt, or similar to other
structures such as walls, ceilings and the like.
It is often necessary to attach an object to a panel
where it is impossible to find a stud or raEter, in thi.s
case the thickness of the panel often provides
insufficient anchorage, also narmally no access is to be
had to the blind side of the panel. A variety of
fasteners have been developed which are partly inserted
through a hole formed in the panel and expanded on the
blind, or inaccessible, side to grip the panel and provide
suficient anchorage.
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Examples of such prior art fasteners include toggle
bolts and various forms of e~pansion bolts.
A typical toggle bolt comprises a metallic bolt
having a head and a threaded rod, and a spring-loaded
wingnut. In use, the wingnut is mounted on the distal end
of the rod.
The wings are then collapsed along the sides of the rod
before being inserted through a hole in a panel. Once
through the hole the wings automatically expand under the
influence of the spring and the nut can be tightened,
gripping the panel between the nut and bolt head.
Toggle bolts require that the diameter of the hole
into which the bolt is to be inserted be larger than the
collapsed spring wingnut. Toggle bolts are also
relatively costly to manufacture and are unsuitable for
soft panel materials e.~. GYPROCK(T.M.) and plaster.
Furthermore the bolt cannot be chanqed or removed without
loss of the spring wingnut.
An e2pansion bolt currently in use comprises a bolt
having a head and a threaded rod, and a fle~ible tubular
sleeve having longitudinal slits e~tending between the end
portions and an internally threaded portion at one end.
In use the bolt is pushed into the unthreaded end of the
sleeve and threadably engaged with the further end. The
rod and sleeve are then inserted in a hole in a panel
until the unthreaded end of the sleeve abuts the sides of
the hole. The bolt is then turned to cause the threaded
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end of the sleeve to be drawn towards the unthreaded end
and the slitted portion to expand and grip the back of the
panel.
Expansion bolts are more suitable for use with soft
panel materials. However, the bolt cannot be removed
without the gripping portion collapsing.
Many other forms of ~astener e~ist but each has
disadvantages. For example, some exhibit a tendency to
rotate about their own axis in the hole when subjected to
torsional forces and thus do not remain stationary when
the bolt is tightened. Others cannot accommodate
different thicknesses of wall.
An object of the present invention is to provide a
panel anchor which avoids or at least ameliorates some of
the aforementioned disadvantages of the prior art
fasteners.
According to the invention there is provided a panel
anchor of the type by means of which a screw or bolt or
similar may be secured to a panel, wall, ceiling or the
like; wherein, the anchor comprises an inner member
defining a channel in which a screw may be secured; and an
outer member; the inner and outer members being threadably
interengageable; the inner member having a relatively
rigid radial flange and the outer member having a
relatively resilient deformable portion; the arrangement
being such that, in
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use, when the two members of the anchor are interengaged
and inserted through a hole in a panel, tightening of the
threaded interengagement between -the two members causes
the deformable portion to extend radially and to
co-operate with the flange to grip opposite sides of the
panel.
Preferably the resiliently deformable portion
comprises a series of longitudinally extending leaves
separated by longitudinally extending slits. Preferably a
weakpoint or hinge is provided at a point along the length
of each leaf so that under longitudinal compressive loads
the leaf is caused to snap outwards in a direction
transverse to the compressive load.
The leaves may be connected at both ends with a
relatively rigid annular portion. Alternatively the
leaves may be connected only at the end which, in use, is
farthest from the radial flange.
The outer member may also be provided with
longitudinally e~tending e~ternal ribs to prevent rotation
of the panel anchor in the hole through which it is
inserted.
The inner member may be provided with internal
projections which are cut by the thread of the screw to
firmly secure the screw within the channel.
In preferred embodiments, both the inner and outer
members are injection moulded. Desirably, the members are
made of nylon 11 material which is strong and has thread
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lubricating properties.
For preference the threads of the inner and outer
members are arranged such that introduction of the screw
acts in the sense which would cause the panel anchor to
grip the panel tighter.
In the accompanying drawingq:
Figure 1 shows an end view of a first member of a
panel anchor embodying the present invention;
Figure 2 shows a section taken along line II-II of
figure l;
Figure 3 shows an end view of a second member of a
panel anchor embodying the present invention; and
Figure 4 shows a section taken along line IV-IV of
figure 3.
Figure 5 shows a series of sectional elecations of
the assembled first and second members in use.
The panel anchor comprises an inner member 1 having a
tubular body 2 with a rigid radial flange 3 at one end, a
central bore 4 or channel and an e~ternal thread 5. In
the present embodiment, the thread 5 has a saw tooth
profile with a thread angle of about 45. This profile
provides a positive connection between inner member 1 and
outer member 9 and is particularly suited to injection
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moulding. Other thread profiles can be used.
Bore 4 has a countersunk opening 6 in flange 3 to
remove any sharp edges and provide a lead to help position
the screw or bolt that is to be used. In the present
e~ample, opening 6 e~tends at an angle of 45 to the bore
axis.
Opening 6 is also provided with four tapered slots 7
to receive the head of a screwdriver. In the present
example, the lower surface of the slots e~tend at an angle
of 26.5 to the bore axis and is designed to receive a
Phillips head screwdriver.
Tubular body 2 is provided with internal, radially
inwardly e~tending projections 8 which bend and are cut by
the thread of a screw as it is inserted and so grip the
screw with a locking effect which resists unscrewing.
Referring to figures 3 and 4 the outer member 9 of
the panel anchor can be seen to comprise a tubular sleeve
having a radial f lange 10 at one end and annular sections
11 and 12 at each end connected by deformable leaves 13
which are separated by long;tudinal slits 14. Also there
is an internal thread 15 integrally formed at end 12 of
the member. A series of intermittent ribs 16 e~tend
longitudinally down each leaf 13 from end 11. Each rib
has a triangular cross-section.
A series of circumferentially aligned hinges or knee
joints 17 are provided in leaves 13 at a position
approximately mid way along their length.
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Each knee joint 16 takes the form of a linear
decrease in section thickness to provide a less resilient
portion that will act as a hinge.
The operation of the anchor will now be described
with reference to Figure 5. In use, the end remote from
flange 3 of inner member 1 is introduced into end 11 of
outer member 9. The outer member 9 is then pushed onto
the inner member 1 until threaded portion 15 engages
external thread 5, and flange 10 of outer member 9 abuts
the underside of flange 3.
The panel anchor assembly can then be pushed through
a hole in a panel 18 until outer member 9 is completely
buried and flanges 3 and 10 prevent further insertion as
shown in Figure 5.
From this position rotation of inner member 1~ say by
means of a screwdriver ;nserted into tapering slots 7,
causes co-operation of threads 15 and 5 to draw end 12
towards flange 3. The outer member 9 is prevented from
rotating by the engagement of ribs 16 with the edges of
the hole. Due to the length of the outer member 9 and the
low torsional resistance of the structure, there would
normally be a tendency for the ou~er member 9 to twist as
the inner member 1 is turned.
This potential problem is overcome by the knee joint
17 providing a weak point in the leaves 13. As the end 12
begins to advance toward flange 10 the resulting
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compressive load on leaves 13 causes the joints 17 to snap
perpendicularly outwards thereby allowing the leaves to
deform, without twisting, as shown in Figure 5. The
leaves 13 continue to e~tend outwardly on the blind side
of the panel as end 12 advances to co-operate with flanges
3 and 10 to grip panel 18. Ribs 16 are intermittent to
facilitate the outward deformation of leaves 13.
A screw 19 may then be threaded into bore 4 of the
anchor. As the thread connecting inner member 1 and outer
member 9 is of the same handing as the screw 19, the
action of tightening the screw is in the sense to
reinforce the grip of the anchor even more tightly.
Because grip is effected by the interaction of the
two members of the anchor the firmness of the grip is not
dependent on the introduction of a screw into the panel
anchor, and this in turn provides the advantage that a
screw introduced into the panel anchor may be removed
without loosening the grip between the anchor and the
panel, and without loosing part of the anchor on the blind
side of the ~anel.
As will be apparent to those skilled in the
appropriate art, the invention may be embodied in other
forms without departing from the scope of the invention
herein disc].osed. For instance, panel anchors embodying
the invention may be of any dimension to accommodate
different thicknesses of wall. Likewise slots 7 may take
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other forms so as to receive other types of screwdrivers,
or other tools. Also, the slits 11 and leaves 1~ of the
outer member 9 need not be longitudinal but could of
course be spiral.
In an alternatiYe embodiment the outer member may
comprise merely a threaded annular portion from which
extend some resilient, or resiliently mounted, flaps which
extend axially and radially from the threaded portion and
which, in use, engage the blind side of a panel and
co-operate with the inner member of the anchor to effect
grip.
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