Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
1 The present invention relate~ to screw clamping pins such
as those encountered in the aeronautic industr~ and more
particularly to specificities of such clamping pins, which
make them more efficient.
The problems of manufacturing costs are as known sig-
nificant factors since enormous ~uantities of clamp pins are
used for example during the manufacturing of a heavy tonnage
aeroplane. The costs result from their design itself which may
be adapted for complete automatization mounting thereof, on
the one hand~ and on the other hand, the nature of the
materials used for their fabrication.
Thus, cheap filled plastic materials having good pro-
perties of mass moulding may be used; they also have an ex-
ternal attractive appearance and colouration in the bulk to
enable them to be identified for visual selection of their
diameters and/or lengths.
Unfortunately, plastic materials have little mechanical
strength much lower than metals, which causes a certain
number of disadvantages.
The prior art teaches in French patent No. 1,433,662 or
U.S. patent Nos. 2,365,787 and 2,345,817 a method of implement-
ing clamp pins between a lower outer body member made e.g. of
plastic material and a corresponding upper outer body member
made e.g. of metal, but the connecting method used based on the
?5 ~imple insertion of said members into one another is not
eompatible with the novel automatic extraction deviees for
elamp pins such as illustrated for example in the Applicant's
Canadian patent applieation serial number 409,334 filed on
August 12, 1982. Such devices conjointly rest on the rearward
portion of the hex.lgon of the clamp pin body and on the assemb-
ly surface, thereby obviously running the risk of disconnection
of both of said body members.
SUMMARY OF THE INVENTION
In order to remedy this first disadvantage, it is
proposed aecording to the invention, to provide in a clamp
pin, a speeific method of connecting a lower outer member of
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1 plastic material, and its corresponding upper outer member
of metalO
Such a connection is provided by a special kind of
threading to enable the metallic hexagonal member to be
axially fitted by compression into the plastic member,
thereby providing the advantage of simplifying and possibly
automatizing the mounting thereof, while permitting sub-
sequent disassembly and reassembly, for example, with a
view to eliminating the rubbery interposition product or
replacing damaged clamp pin portions.
In the second place, there is also proposed accord-
ing to the invention a unique anchoring method for the
spreader of the clamp pin branches, which results from the
above mentioned specific connecting method applied to both
of said members.
The invention will now be better understood in
the following description of a clamping pin by reference to
the following figures contained in the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a partial longitudinal cross section
of the screw clamp pin at full insertion in the materials
to be clamped;
Fig. 2 show~s a side view of the screw clamp pin
shown in Fig. l;
Fig. 3 shows a partial longitudinal cross section
- of the screw clamp pin of Fig. 1 in final clamping
position;
Fig. 4 shows an enlarged partial longitudinal
cross section of the upper and lower outer body of the
screw clamp pin of Figs. 1, 2 and 3 illustrating the
special thread type con~iguration on these members.
DESCRIPTON OF THE INVENTION
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A screw clamping pin as shown in Figures 1, 2 and 3
necessarily comprises a pair of clamping branches 1 and 2,
and a branch spreader 3, which both are disposed in the
hole 4 formed in the assembly 5, with a body denoted as a
whole by 6 resting on the assembly surface 7.
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1 On the body 6 of the clamp pin there is mounted
a spring 8 through the center of which passes a rod denoted
as a whole by 9, and a supporting washer 10 provided a
seat for a nut 11 arrested in abutting relationship by an
end cap 12~
The rod 9 includes on the one side a smooth part
at the bottom o the thread 9a thereo~ to enable the nut
11 to turn idle, and on the other side, a hexagonal part
9b which is longitudinally slidable in a corresponding
longitudinal female portion 6c formed in body 6.
Said rod 9 is terminated by a part 9c which is
made of-a material capable of being crimped so that it
may clampingly surround end portions of branches 1 and 2,
which are adapted to maintain the radial positioning of
the spreader 3, disposed therebetween.
The body 6 comprises an upper metallic member 6a
having on the one side an outer hexagon and on the other
side, an inner stepped portion the function of which will
be explained hereinafter.
The specific connecting method according to the
invention which is used at 13 results from the provision of
a male member formed with a thread thereon of the so-
called "artillery" type, in its central area 6a, and
axially force fitted in the plastic sleeve constituting
the portion 6b.
The essential characteristics of this type of
thread located on male member 6a and female member 6b is
that the, otherwise helical, thread comprises flanks
74a on one side of the thread which are substantially
perpendicular to the longitudinal axis of the screw clamp
pin 75, as shown in Fig. 4, and on the other side of the
thread are thread flanks 74b inclined in the same way as
the usual thread flanks.
In this way the hexagonal member 6a can be
positioned merely by driving it axially into the member 6b
while it can be subsequently easily removed therefrom by
the usual unscrewing.
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1 The holding in position of the spreader 3 simply
results from the positioning of members 6a and 6b by making
the latter tighten a first washer 14 therebetween, then
putting the branches 3a and 3b of said spreader between said
washer 14 and another washer 15, in alignment with the
stepped portion 16 formed in the member 6a such that the
members axe interlocked as soon as both of said members 6a
and 6b are assembled.
It will now be explained how the clamp pin is
implemented in the same way as the known clamp pins without
having the disadvantages thereof.
The positioning of the clamp pin into the hole 4 is
effected when the nut 11 is totally unscrewed and the
rod 9 is moved down to the maximum (this position sub-
stantially corresponds to that of Figures 1 and 2).
The clamp pin is locked in rotation by a nose ofa screwing means (not shown) which clampingly surrounds
the hexagon of member 6a.
After the nut 11 has been screwed on by the inner
part of the nose of the screwing means (not shown), the
rod 9 moves up again thereby resulting in the assembly 5
being tightened-by means of the ends la and 2a of branches
1 and 2, pushed apart by the spreader 3 as shown in Fig. 3.
The screwing is continued up to a predetermined
torque to permit compression of the spring 8 which ensures
tightening of the assembly 5 through its biasing force
by energy recovery.
It is necessary to tighten the assembly because of
the presence of a polymerizable interposition product
between the sheets constituting the assembly.
After polymerization of the product, the clamp
pin is pulled out of the hole ~ in a reversed sequence of
steps by unscrewing the nut 11 thereby driving the rod 9
toward the assembly as shown in Figs. l and 2 and extracting
the clamp pin, said extraction being carried out by provision
of an application point at 17 under the hexagon of member
6a, and advantageously, another application point over the
surface 7 of the assembly.
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_ During said motions, rotation of ~rod 9 is prevented
due to the presence of the hexagon 6c which receives the six-
sided member 9b, thereby correlatively causing,branches 1
and 2 to be locked in rotation simultaneously wi:th
spreader 3.
Summarizing, according to the invention, there ls
proposed a clamping pin of improved design properties
resulting in increased mechanical qualities as well as
reduced manufacturing costs due more particularly to the
nature of some of the materials used and the facilities
for realizing automated mounting thereof.
The nature of the materials used is advantageously
such that the upper member 6a is made of an electrolytically
protected steel and the lower member 6h, of a plastic
material "RILSAN" ( a Trade Mark of Aquitaine-Organico for
chemical compositions such as a polyamide for moldings,
extrusions, or coatings).
It will be understood that this invention was only
described and represented in a preferential exemplifying
mode of embodiment and that technical equivalents can be
substituted for its constitutive parts without departing
from the scope thereof.
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