Note: Descriptions are shown in the official language in which they were submitted.
1o66~77
F~EXI3LE SCREli~ ANCH~:)R
The innovation relates to an insert element for fastening
- purposes consisting of elastically deformable material
having an outer contour serving to anchor the element in a
workpiece opening and a reception opening cooperating with
a fastening element, preferably a screw.`
Insert elements in the form of plug-in type nuts, dowels
or the like are known from many instances. They are
normally inserted in a rough-bored opening of a workpiece
and serve to receive a fastening element, preferably a
screw or the like which is received in the re^eption opening
of the insert element. The known insert or plug-in type
elements are normally formed in one piece and normally
consist o~ a head and a shank portion, wherein the shank
portion may comprise two or more legs which are urged
against the wall of the opening when the screw, for example,
is introduced while being rotated,.and thereby in the manner
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of a talon additionally fasten the insert element in the
workpiece.
The most frequently used insert element or plug-in type nut
normally comprises two legs formed integrally wi~h a head
plate. When driving-in the fastening means such as a screw,
the legs are urged outwards against the wall of the opening,
with the screw being encompassed in the region of the flexi~le
legs in a segment-like manner only and the latter being urged
against the screw through their own bias only. The main dis-
advantage of the kno~m plug-in type elements, however, resides
in that the axis of the screw hole has got to coincide with
the axis of the screw. Oblique screwings are possible with
such plug-in type nuts only if the axis of the screw hole is
at angles with respect to the normal direction of fastening of
the plug-in type nut. But here as well the axis of the screw
hole and the axis of the fastening means must coincide which
is brought about only by a certain angular position of the
plug-in type nut.
The innovation is based upon the problem of providing an
insert element for fastening purposes in which the fastening
element may be inserted at any acute angle with respect to
the insert element.
With an insert element of the type mentioned at the beginning
this problem is solved in that the reception openlng is
defined by a funnel-shaped, radially deformable :inner portion
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~066~77
of the insert element.
,
With the insert element according to the innovation the
reception opening or screw hole is formed conically, the
diameter of introduction being essentially greater than the
diameter of the fastening element which, for example, may be
a self-forming screw. As the funnel-shaped portion is
elastically deformabls there ~ill result upon the screw being
driven in a deformation of the funnel-shaped portion which will
be dra~m in a direction towards the screw head and thereby
will guarantee an encompassing of the fastening element
depending upon the ti~hteni~g force of the screw. A pre-
requisite to obtain the effect aimed at of introducing ~
fastening element also at an oblique angle &part from the
elastic deformability of the funnel-shaped portions consists
in that the latter be furthermore afforded an opportunity
sufficiently to deform itself because the lower part of the
funnel-shaped portion preferably will become aligned a~ially
of the aY.is of the screw element positively upon the iastening
element being driven in. In connection with this there results
a relatively strong radial deviation of the corresponding
portion of the funnel-shaped portion which, however, will be
possible only if there is nothing to obstruct the radial
deviation.
~ith the aid of the innovation, an insert element has thus
been provided which is capable of adapting itself to the
respective obli~ue position of a fastening element, for
examplea scre~i, while simultaneously well encompassing the scre~
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.
From this there results also a technical advantage of the
lnnovation from a mounting point of view insofar as the plug-in
type nut according to the innovation no longer has to be
exactly--oriented with respect to the axis of the screw as
had to be the case with the previously used plug-in type
nuts.
Provision is made in one further development of the innovation
for one outer wall portion to be connected with the funnel-
shaped inner portion through an axially limited connection
portion only in such a manner that the inner portion may be
pivoted with respect to the outer wall portion. The outer
wall portion may be of different axial lengths but with
thinner workpiece plates, ho~Jever, at least must extend a
distance at least slightly in excess of the workpiece thick-
ness. The funnel portion which is either longer or shorter
than the outer wall portion, depending upon the purpose for
which it is used, will be situated radially within the outer
wall portion and will be connected with the latter through a
pivotal connection only so as to guarantee deformability of
the funnal portion with an obliquely applied fastening element.
The connection portion preferably is dispoed within the head
region of the insert element, because the strongest radial
deviation of the funnel portion takes place at the free end.
In accordance with another further development of the innovation
provision is made for the funnel portion to be of approximately
equal wall thickness over the length thereof. But it is also
possible to vary the wall thickness over the length in which,
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however, a sufficient degree of axial deformability of the
funnel portion must be secured in any case with an obliquely
applied fastening element, and simultaneously a sufficient
force of retention against withdrawal of the fastening element
from the funnel portion and of preventing the latter from
turning inside out.
As already mentioned above the funnel portion is designed in
such a manner that it on the one hand has a sufficient degree
of inherent flexibi~ty to adapt itself to the respective
oblique position of the screw and that it on the other hand
secures good encompassing of the screw. In this connection,
provision is made in another embodiment of the innovation for
a constant diameter end portion to join the funnel portion,
said constant diameter being preferably equal to the smallest
diameter of the funnal portion. A particularly effective
encompassing of the screw, accordingly, takes place in the
constant diameter end portion.
It may indeed be imagined that the funnel portion might be
formed of several separate, elastically deformable branches
or legs, In order to secure, however, a sufficient degree of
strength, provision is made in accordance with a~ther embodi-
~ent of the innovation for the funnel portion to be formed ofa closed circumferentially extending funnel wall which is
weakened at circumferentiaIly spaced intervals. In this manner
there will be obtained an effective fastening of a screw while,
however, the weakenings take care to avoid any tearing which
might occur in the lower portion caused by too ~ligh a
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tangential stress. In accordance with another further develop-
ment of the innovation the weakenings may be in the form of
longitudinally extending grooves pointing towards the reception
opening, said grooves preferably ~orming membrane-like elon-
gation portions. ln this arrangement the weakenings of the
funnel portion have a shorter peripheral length than the
portions disposed therebetween.
The insert element according to the innovation may be employed
for workpieces of different materials, for example, for an
interconnecting construction for plate-shaped workpieces of
wood, chip board or the like. In this connection, the inno-
vation in one embodiment thereof provides for the outer wall
portion to be designed in the form of a sQw-toothing. The teeth
take care of an effective anchoring in a bore, for example,
a blind bore in a wood plate. Such an anchoring, however, is
important because the driving-in of the fastening element
does not contribute anything towards a reinforcement of this
anchoring. In order to secure the insert element against
rotation, provision is made in another further development of
the innovation for the outer wall portion to comprise outside
flattenings extending in parallel with the axis.
The last-d~scribed embodiment of an insert element is particu-
larly suited for connections of parts of furniture or the like.
But there are quite a few cases of application where the insert
element is to be inserted into relative~y thin workpieces such
as sheet metal for example. In this connection, provision is
made in another further development of the innovation ~or the
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outer wall portion to comprise a head having a contact surface
lying closely against the workpiece surface, and for inter-
locking means to be provided in addition which are adapted to
be brought $nto engagement with the underside of the workpiece.
Such a further development of the insert element according
to the innovation makes it possible to use self-forming screws
even in cases of application where they are not normally
employed.
So that sufficient coverage of the fastening screw may be
obtained, the axial length of the funnel portion in case of
insertion in sheet metal material or the like exceeds the
length of the openings in which the element is to be anchored.
The anchoring or interlocking in this case may again be
effected in different ways. In one further embodiment of the
lnnovation provision is made for the outer wall portion to
comprise two or more spring legs having an undercut engaged
by the opening edge averted from the head. The spring legs
in this arrangement take care of a spanning of the insert
element, in that the workpiece "is clamped in" from opposite
sides of the workpiece.With another further development of
the innovation provision is made for the outer wall portion
to comprise two or more spring leg~. which are bent outwards
and back again at the lower end thereof and which by their
~ee ends get into engagement with the opening edge averted
from the head. With this embodiment, so-called expansion
feet take care of an irreproachable positioning in the
hole, with extraordinarily high tightening forces being
obtained. - 8 -
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In all the cases where snapping feet or expansion feet are
utilized to anchor the insert element according to the in-
novation, it is advantageous to Provide radially extending
arresting cams between the spring legs integrally formed with
the funnel portion and/or with the head which permit of a better
positioning in the fastening aperture.
A third possibility of anchoring in the workpiece according to
the innovation consists in that there are four projections in-
tegrally formed with the head forming a square and in that there
are another four pro~ections forming a square, formed integrally
with thelhead or the outer wall portion which are axially sl>aced
from and offset by 45 with respect to the first pro~ections.
This embodiment in the first place is for quadratic fastening
apertures, with the insert ele~.ent when inserted being ~ositive-
ly interlocked in the quadratic aperture by rotation thereof
through 45.
Thus broadly, the invention contemplates a fastener device which
is formed of an elastically deformable material and which in-
cludes a workpiece anchoring portion having an outer wall portion
adapted for anchoring to a workpiece opening and having a gener-
ally axially extending opening adapted for receiving and co-
operating with a fastening element. The opening which is defined
by a radially deformable inwardly extending element has an in-
wardly extending funnel-shaped portion connected at its diametr-
ically larger end with the outer wall portion of the workpiece
anchoring portion, and the element has an inner portion of constant
diameter extending inwardly from and of substantially the same
diameter as an inner end of the funnel-shaped portion.
In the following, some exemplary embodiment of the innovation
3~ will be described in more detail by way of the drawings:
FI~.. 1 shows a sectional view of the insert element according to
the innovation in connection with a workpiece,
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Fig. 2 shows a top plan view of the arrangement according
to Fig. 1,
Fig. 3 shows another workpiece connected with the workpiece
accord~ng to Fig. 1,
Fig. 4 shows a sectional view of another embodjment of
'' the innovation,
Fig. 5 shows a top plan vie~ taken in the direction of the
arrow X,
Fig. ~ shows a sectional view of anothe~ embodiment of the
innovation,
Fig. 7 shows a view of the element according to Fig.
taken in the direction of the arrow Y,
Fig. 8 shows a sectional view of a fourth embodiment of
the innovation,
Fig. 9 shows a view of the arrangement according to Fig.
taken in the direction of the arrow Z.
A wooden plate 10 according to Fig. 1 is provided with a
blind bore 11 having a plug-in type nut 12 inserted therein,
with anchoring teeth 4 of a sleeve-shaped outer wall portion
13 taking care of an effective anchoring i,n the ~ore 11.
Four rotation preventing flanges 5 (Pig. 2) which are
offset from each other through 90 take care of a suffic-
ient degree of safety of the Plug-in type nut 12 against
rotation. A funnel nortion 1 com~rising a conical
portion 15 having an oPening angle CCand a lower ~ortion
3 of constant diameter is ~ivotally connected in
the upper region of the outer wall Portion 13 through a
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1 o 1066177
connecting portion 14. The portion 1~ de~ines a conical
screw-in opening passing o~er into a constant diameter opening
in portion 3, said constant diameter ~eing equal ~o the
smallest diameter of' the conical portion 15. The ~unnel 1 is
composed of' f'our segments 1~ equally spaced ~'rom each ot~ler
on the periphery and having a~out the same wall thi.ckness
in a longitudinal direction thereof~. Between the segments 1~
there are mem~rane-like elongated portions which are formed by
grooves 2.
~`igure ~ shows another plate 17 likewise o~' wood, lor example,
which possesses an o~lique, stepped ~ore 18 with a screw 19
guided therethrough. The screw head 20 is countersun~ in the
portion of maximum diameter, while the lower region o~ the
self'-~'orming shank 21 cooperates with the screw hole o~' the
~'unnel 1, wi~h the ~'unnel walls ~eing strongly de~ormed ~ecause
the screw strives to de~'orm the elas~ic material in such a
manner that it is oriented in parallel with respect to the
axis of the screw.
But there is yet obtained a high degree of coverage of thread
due to the end portion 16, in particular, so that the work-
pieces 10 and 17 may be securely connected with each other.
Figures 4 and 5 show a sheet metal plate 22 with a square hole
2~ to receive a plug-Ln type nut 24. The latter in its turn
possesses an inner funnel 25 which is formed in a similar
manner as the funnel 1 of the plug-in type nut acc.ording to
Figures 1 and 2. But in the present case it is formed integrally
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66177
with a hea~ plate 2~ which forms a do~nwardly projecting sq~are
27 at the underside thereof. As will be seen from Figure 5,
there are furthermore provided at the head 2~ rectangular
projeotions 2~ defining another square and offset by 45 with
respect to the corners of the square 27. Besides, the pro-
jections Z8 are axially offset with respect to the souare 27,
so that through rotation of the entire plug-in type nut 24
the latter may be positively interlocked in the square hole
23.
Figures ~ and 7 show a plug-in type nut 3O of a design similar
to tha-t according to Figures 4 and 5 as far as the funnel 31 an~
the head pl~te 32 are concerned. Snapping feet7serve ~r a~horing
in a sheet met~1 plate 33 having a square opening ~4, said snap-
ping feet being provided with an undercut ~5 for the purpose O,T
exerting clamping forces from opposite sides of the sheet metal
plate 33. As may be seen from Figure 7, there are pro-
vided two diametrically opposed snapping feet 7. Arresting cams
8 are provided at the two other sides of the plug-in type nut
which come to lie closely against the ~rall of the hole 34, so
that the plug-in type nut 3O is effectively positioned.
Figures 8 and 9 show a sheet metal plate 3~ provided ~itn a
square opening 37 havir.g a plug-in type nut 3~ inserted -chere.
in which again resembles the plug-in type nut according to
Figures ~ and 7. The funnel 39 too is of the same desi~n, so
that a more detailed description of this part may be omitted.
Two diametrioally opposed spring legs 10 are provided to anchor
the plug-in type nu-t 38 in the square hole 37, said spring legs
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being bent outwards and back again at the lower end thereof,
with the free ends of the spring legs 10 or expansion feet
coming to lie closely against the lower edge of the aperture.
The spring legs 10 permit of an extraordinarily easy assembly
and are at the same time effective to bring about increased
tightening forces due to the self-locking effect of the
spring legs 10. Arresting cams on the two other sides of the
plug-in type nut 38 take care of an improved positioning in
the square hole 37.
The material used for the plug-in type nut in accordance with
the innovation must be sufficiently flexible and yet guarantee
a high degree of strength. Therefore, synthetic material
is preferably used.
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