U.S. patent number 3,712,655 [Application Number 05/089,542] was granted by the patent office on 1973-01-23 for plastic seal.
This patent grant is currently assigned to Stoffel Steel Corporation. Invention is credited to Charles Fuehrer.
United States Patent |
3,712,655 |
Fuehrer |
January 23, 1973 |
PLASTIC SEAL
Abstract
An all plastic seal in which the socket receiving the locking
head of a strap connected to the seal body is provided with a
housing open at both ends that is of such a ratio in its length to
the opening in the housing at the end opposite where the locking
head is inserted that access to the locking fingers is
substantially precluded; additionally, the housing may be provided
with inwardly projecting fluke-like projections minimizing the
freedom of movement of the head in its locked condition in a
direction transverse to the axial dimension of the housing.
Inventors: |
Fuehrer; Charles (Scarsdale,
NY) |
Assignee: |
Stoffel Steel Corporation (New
York, NY)
|
Family
ID: |
22218230 |
Appl.
No.: |
05/089,542 |
Filed: |
November 16, 1970 |
Current U.S.
Class: |
292/321;
24/704.2; 292/317; 292/322; 24/16PB |
Current CPC
Class: |
F16B
21/071 (20130101); G09F 3/0352 (20130101); Y10T
292/494 (20150401); Y10T 292/50 (20150401); Y10T
24/505 (20150115); Y10T 292/499 (20150401); Y10T
24/1498 (20150115) |
Current International
Class: |
F16B
21/07 (20060101); F16B 21/00 (20060101); G09F
3/03 (20060101); B65d 055/06 () |
Field of
Search: |
;292/37R,27A,317,318,319,320,321,322 ;24/16,16PB,3.5P,26A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolfe; Robert L.
Claims
What I claim is:
1. A seal which includes a housing means, a locking socket means, a
tie-member operatively connected to the housing means, and a
locking head means provided at the free end of the tie-member for
insertion into the socket means to lock the seal, the socket means
including inwardly projecting prong-like locking elements and the
head means including a head portion with a shoulder and of such
dimension as to elastically expand the prong-like locking elements
during insertions thereof so that the shoulder formed between the
head portion and an adjoining section with smaller cross section
snaps in behind the end surfaces of the prong-like locking elements
when the head portion is inserted into said socket means, the
housing means being provided with internal longitudinally extending
bore means open at both ends thereof, the socket means being
located near one end of the housing means and being enclosed by
said bore means, and wherein the housing means is provided in said
bore means with inwardly projecting means at least in the area
behind the end surfaces of the locking element substantially
minimizing the freedom of movement of the head portion in the bore
means, when in the locked position thereof, in a direction
transverse to the longitudinal axis of the housing means.
2. A seal according to claim 1, characterized in that said bore
means is of substantially circular cross-section.
3. A seal according to claim 1, characterized in that said bore
means is of substantially rectangular cross-section.
4. A seal according to claim 1, characterized in that the
dimensions of said shoulder and of the adjoining section of smaller
cross-section are so chosen that the connection of the head portion
with said adjoining section forms a place of intentional failure in
case of tampering with the seal.
5. A seal according to claim 1, characterized in that said inwardly
projecting means is formed by substantially longitudinally
extending flutes provided on the inside of the bore means.
6. A seal according to claim 1, characterized in that said
tie-member and said housing means are of substantially circular
cross-section.
7. A seal according to claim 1, characterized in that said
tie-member, said head means, and said housing means are
substantially flat with an approximately rectangular cross-section
of relatively slight thickness.
8. A seal according to claim 5, characterized in that the
tie-member is connected to one side of a seal body, and the housing
means is located at the other side thereof.
9. A seal according to claim 8, characterized in that said body is
relatively flat while said tie-member, head means and housing means
are of substantially circular cross-section.
10. A seal according to claim 8, characterized in that said body,
said tie-member, said head means, and said housing means are
substantially flat.
11. A seal according to claim 4, characterized by further means in
the form of at least one additional cut-out constituting an
intentional place of failure in case of tampering with the
seal.
12. An all-plastic seal according to claim 1, characterized in that
the inwardly projecting means are constructed as flute means
extending longitudinally from the area of said socket toward said
other end and substantially preventing any wiggling of the head
when in the locked position.
13. A seal according to claim 1, characterized in that said seal is
of a unitary construction.
14. A seal according to claim 13, characterized in that said seal
is constructed entirely of homogenous plastic material.
15. A seal according to claim 5, characterized in that said flutes
have a uniform cross-section throughout their length, and in that
said flutes extend from the other open end up to a position
immediately adjacent the prong like locking elements of the socket
means.
16. A seal according to claim 15, characterized in that said seal
is of a unitary construction.
17. A seal according to claim 16, characterized in that said seal
is constructed entirely of homogenous plastic material.
18. An all plastic seal according to claim 12, characterized in
that the ratio of the dimension of said housing in the longitudinal
direction to the maximum dimension of the cross-section of said
passage is at least 5:2.
19. An all-plastic seal according to claim 18, characterized in
that said seal is of a unitary construction.
20. A seal according to claim 1, characterized in that said head
means includes a stop member spaced from said shoulder a distance
corresponding to the distance between the end surfaces of the
prong-like elements and the end surface of said housing means
immediately surrounding the bore means at the one end of the
housing means whereby longitudinal movement of said head means is
precluded by engagement of said stop means with said end surface of
said housing means once the head portion is snapped in position by
the prong-like locking elements.
21. A seal according to claim 20, characterized in that the end
surface of said housing means and the end surfaces of said
prong-like elements extend substantially transversely to said
longitudinally extending bore means.
22. A seal according to claim 21, characterized in that the seal is
of a unitary, homogenous plastic construction.
23. A seal according to claim 15, characterized in that said head
means includes a stop member spaced from said shoulder a distance
corresponding to the distance between the end surfaces of the
prong-like elements and the end surface of said housing means
immediately surrounding the bore means at the one end of the
housing means whereby longitudinal movement of said head means is
precluded by engagement of said stop means with said end surface of
said housing means once the head portion is snapped in position by
the prong-like locking elements, the end surfaces of said housing
means and the end surfaces of said prong-like elements extending
substantially transversely to said longitudinally extending bore
means.
24. A seal according to claim 1, wherein the ratio of the dimension
of the bore means in the longitudinal direction to the smallest
cross-sectional dimension of the bore means at the other open end
opposite the socket means is such as to substantially preclude
access to the locking elements from the said other open end of the
housing means when the head portion is lockingly inserted into the
socket means.
25. A seal according to claim 15, wherein the ratio of the
dimension of the bore means in the longitudinal direction to the
smallest cross-sectional dimension of the bore means at the other
open end opposite the socket means is such as to substantially
preclude access to the locking elements from said other open end of
the housing means when the head portion is lockingly inserted into
the socket means.
26. A seal according to claim 17, wherein the ratio of the
dimension of the bore means in the longitudinal direction to the
smallest cross-sectional dimension of the bore means at the other
open end opposite the socket means is such as to substantially
preclude access to the locking elements from said other open end of
the housing means when the head portion is lockingly inserted into
the socket means.
27. A seal according to claim 24, characterized in that said ratio
is at least 5:2.
28. A seal according to claim 27, characterized in that the
smallest cross-sectional dimension is at most of the order of 0.2
inch.
29. A seal according to claim 24, characterized in that said
inwardly projecting means is formed by substantially longitudinally
extending flutes provided on the inside of the bore means.
30. A seal according to claim 25, characterized in that said ratio
is at least 5:2.
31. A seal according to claim 26, characterized in that said ratio
is at least 5:2.
32. A seal according to claim 27, characterized in that said bore
means is of substantially uniform cross-section from said other
open end up to a position adjacent the prong-like elements.
Description
The present invention relates to a plastic seal, and more
particularly, to a self-locking tamper-proof seal made from
synthetic resinous material.
Various plastic padlock and hasp seals are known already in the
prior art. However, all of these prior art seals entail certain
disadvantages, particularly as regards ease of manufacture and cost
involved as well as tamperproofness in operation.
One prior art construction of a fastening device of this type (U.S.
Pat. No. 3,402,435) consists of a filament, adapted to be attached
to a tag, which is provided with a slotted socket forming fingers
to receive the head at the end of the filament. However, the socket
of this prior art construction is exposed so that the fingers can
be easily spread to enable removal of the head. To enhance its
tamper-proof characteristics, this prior art construction not only
proposes a reduced diameter neck directly behind the head but also
proposes an increase in brittleness at the neck, thereby requiring
an additional annealing step in its manufacture. However, the ease
of removal of the head by spreading the fingers defeats the
additional safety measures of this prior art construction, apart
from its increased manufacturing cost due to the required annealing
operation.
Another prior art construction (U.S. Pat. No. 3,466,077) proposes
to completely enclose the finger portions of the socket within a
housing surrounding the socket to render such a seal more
tamper-proof. In such prior art construction one housing end is
completely closed. However, such a construction entails a
substantial drawback as regards ease of manufacture and involved
manufacturing costs since it requires an additional operating step,
by the use of a die under suitable heat and pressure, to close the
end of the housing by drawing in the wall of the end of the housing
to be closed. Since plastic seals of this type are mass-produced,
the additional step involved in closing the end of the housing in
this prior art construction directly and substantially affects the
cost thereof.
Other types of plastic seal constructions are also known in the
prior art. In one such prior art construction (U.S. Pat. No.
3,146,012) the interlocking slotted housing is not only relatively
complicated but is far from being tamper proof since access can be
had to the interlocking parts by way of the openings thereof. In
another such prior art construction (U.S. Pat. No. 3,367,701) the
times of the engaging member are readily accessible from the open
end of the socket, not to mention the fact that the interlocking
parts are relatively complicated in design.
The present invention has at its purpose to eliminate the
aforementioned shortcomings and drawbacks encountered in the prior
art and to provide an all-plastic seal which is substantially more
tamper-proof yet is simple in construction as well as easy to
manufacture.
The self-locking seal of the present invention includes a housing
accommodating the locking socket which is of such dimensions and
construction that the interlocking parts cannot be reached by items
in the normal possession of a person, such as a pencil, ball point
pen or the like which could be used to reopen the interlocking
parts by inserting, for example, the end of a small mechanical
pencil into the open end of the socket housing and gradually prying
open the socket fingers as the head portion is wiggled back and
forth, ultimately permitting its withdrawal out of the socket.
Accordingly, the present invention has as its principal purpose to
eliminate the drawbacks and disadvantages of the prior art and to
provide an all-plastic padlock seal that is considerably more
tamper proof than the prior art devices without requiring
additional manufacturing steps increasing the cost thereof. The
present invention essentially consists in that the housing
surrounding the locking socket has such a ratio of length to
diameter of its bore as to make it substantially impossible to get
at the locking prongs when the seal is closed and still effect a
sufficient movement of the locking fingers. Additionally, as a
further tamper-proof feature, flutes are provided on the inside of
the housing which prevent the locked head from being wiggled in a
substantially transverse direction to its ultimate with-drawal out
of the socket.
Accordingly, it is an object of the present invention to provide a
plastic seal of the type described above which avoids by simple
means the aforementioned shortcomings and drawbacks encountered in
the prior art.
Another object of the present invention resides in a plastic seal
of the type described above which can be manufactured in a simple
manner without requiring any additional manufacturing steps other
than the single molding operation thereof.
A further object of the present invention resides in an all plastic
padlock seal which excels by its tamper-proof characteristics yet
can be readily manufactured by mass production techniques utilizing
conventional injection or pressure molding.
A still further object of the present invention resides in a
plastic seal of the type described above which obviates any
after-treatment of the molded seal.
These and further objects, features and advantages of the present
invention will become more obvious from the following description
when taken in connection with the accompanying drawing, which
shows, for purposes of illustration only, several embodiments in
accordance with the present invention, and wherein
FIG. 1 is an elevational view of an all-plastic padlock seal in
accordance with the present invention, illustrating the socket
housing thereof in axial longitudinal cross-section.
FIG. 2 is a bottom plan view of the seal of FIG. 1.
FIG. 3 is a cross-sectional view taken along line III--III of FIG.
1.
FIG. 4 is a view, similar to FIG. 2, and showing certain details
thereof on an enlarged scale.
FIG. 4a is a cross-sectional view taken along line IV-IV of FIG.
3.
FIG. 5 is a partial cross-sectional view taken along line V--V of
FIG. 4.
FIG. 6 is an elevational view, similar to FIG. 1, of a modified
embodiment of an all-plastic padlock seal in accordance with the
present invention.
FIG. 7 is a partial bottom plan view of FIG. 6.
FIG. 8 is a cross-sectional view, taken along line VIII--VIII of
FIG. 6.
FIG. 8a is a cross-sectional view taken along line A--A of FIG.
8.
FIG. 9 is an elevational view of a still further modified
embodiment of the plastic seal of FIG. 6, and
FIG. 10 is a side view of the seal of FIG. 9.
Referring now to the drawing, wherein like reference numerals are
used throughout the various views to designate like parts, and more
particularly to FIGS. 1, 2 and 3, reference numeral 10 generally
designates a flexible tie-member provided at its free end with a
locking head generally designated by reference numeral 20 and
secured at the other end to one side of a relatively flat body
generally designated by reference numeral 30 which includes at the
other side thereof, a locking housing generally designated by
reference numeral 40 provided with a locking socket for the head
20. The body 30 in the illustrated embodiment is of approximately
rectangular shape and of a thickness slightly smaller than the
diameter of the substantially circular tie-member 10. However, the
relatively flat body 30 may also be of any other suitable
configuration and thickness, as may be desired for a particular
use, for example, to contain a desired information on its front
and/or back surface which may be formed thereon directly during the
molding operation. Additionally, the body 30 may be provided with a
rim 31 surrounding the main surface 32 recessed relative thereto
which will receive the information. Since this information may be
realized, for instance, by suitable engraving of the mold, the base
30 can be made to appear attractive. A small reinforcing
enlargement 11 approximately spherically shaped may be provided in
the member 10 near its connection with the body 30.
The locking head 20 includes at its free end an approximately
triangularly-shaped locking head portion 21 having slightly curved
tapering surfaces. The head portion is adjoined by a tapering
section 22 having its smaller diametric dimension adjacent the end
surface 21' thereby forming an intentionally weakened place at the
connection between surface 21' and section 22 adjacent the
substantially flat end surface 21' of the head portion 21 which
will break in case of tampering with the tie member 10, when
someone attempts to unlock the seal. The tapering portion 22 is
adjoined by a substantially cylindrical portion 23, followed in
turn, by an enlargement 24 similar to the reinforcing enlargement
11 and constituting a stop member. Several annular beads 25, which
are spaced at equal distances and follow the enlarged portion 24,
provide a gripping area where the tie member 10 can be firmly
gripped during the locking operation.
The socket housing 40 is formed of a cylindrical sleeve 41 open at
the bottom end and provided at the top with a flaring section 42.
The flaring section 42 is provided with an axial bore 43 of a
diametric dimension slightly larger than the maximum diametric
dimensions of the head portion 21 and of the cylindrical section
23, but smaller than the diametric dimension of the enlarged
abutment 24 so that the head 20 can be inserted into the bore 43
with its head portion 21, tapering section 22 and cylindrical
section 23 until the enlargement 24 abuts against the upper end
surface 42' of the housing 40. Prong-like locking fingers 44, each
of which defines on the inside thereof a part of a frusto-conical
surface complementary to the surface of section 22, extend inwardly
and downwardly within the housing 41, thus forming an interrupted
tapering section 45 of frusto conical shape. The length of the
frusto conical opening 45 formed by the locking fingers is thereby
substantially equal to or very slightly larger than the length of
the tapering section 22 and the length of the bore 43 is thereby
substantially equal to or very slightly larger than the length of
the cylindrical section 23 so that the head portion 21 snaps into
its locked position with the flat surface 21' thereof engaging
against the end surfaces 44' of the prong-like fingers 44 when the
abutment engages the end face 42' of the housing 40.
By making the ratio of the length L to the diameter D (FIGS. 1, 3
and 5) sufficiently large, for example by making this ratio greater
than 5:2, it will be impossible to get at the prongs 44 when the
seal is closed, particularly if the diametric dimensions D are
relatively small, for example of the order of a quarter inch or
less. However, in order to further enhance the tamper-proof
characteristics of the seal according to the present invention,
inwardly projecting flutes 47 of approximately triangular cross
section and arranged intermediate the locking fingers 44 are
provided on the inside of the housing 40 which extend essentially
from the open end of the cylindrical housing 41 to the tapering
part 42 thereof. Owing to the presence of the flute-like
projections 47, the head portion 21 is substantially prevented from
being moved to any substantial extent in the transverse direction,
i.e., in a direction at an angle to the axis of the housing 40,
thus making it impossible to withdraw the head 20 out of the socket
formed by prongs 44 by wiggling the head 20 around to work it back
past the prongs 44, possibly while attempting to spread the prongs
44 apart. Furthermore, in the event of an excessive force used in
the attempt to open the seal, the member 10 would break at its
intentionally weakened place in the area of the connection between
the head portion 21 and tapering section 22, thereby indicating the
tampering with the seal.
The embodiment of FIGS. 6, 7 and 8 is substantially similar to
FIGS. 1 through 5 and similar parts thereof are designated by
corresponding reference numerals of the 100 series. However,
differing from the first embodiment, the flexible tie-member 110 of
the embodiment of FIGS. 6, 7 and 8 is substantially flat and of
rectangular cross-section, i.e., has a thickness substantially
corresponding to the thickness of the body 130 and a width that is
a multiple of its thickness, as can be seen from a comparison of
FIGS. 6 and 8 where the thickness is indicated by T (FIG. 8) and
the width by W (FIG. 6). Additionally, the head portion 121 is of
similar flattened configuration, as can also be seen in FIGS. 6 and
8. Also, the head portion 121 is of partially frusto-conical and
partially cylindrical configuration, adjoined again by a tapering
section 122 which is followed by a cylindrical section 123 and an
annular shoulder 124 again forming an abutment. In lieu of annular
beads, several raised, very fine embossments 125 are provided to
facilitate gripping of the tie-member 110 during the closing of the
seal. Contrary to the circular configuration of the housing 40, the
housing 140 of this embodiment is also of substantially rectangular
configuration, provided with only two prong-like locking fingers
144 and with four flute-like projections 147 extending inwardly
from the narrow sides of the rectangle so as to reduce the free
space in the direction of the longer side of the substantially
rectangular opening. The flute-like projections 147 again prevent
the head 120 from being worked back past the prongs 144 by wiggling
the head 120 around in the housing 140.
The ratio of length L in this embodiment to the dimension D' (FIGS.
6 and 8) is again chosen so as to be of the order of 5:2 or larger
to improve the tamper-proof characteristics, especially with
dimension of D' of the order of an eighth of an inch or less.
The embodiment of FIGS. 9 and 10 differs from that of FIGS. 6
through 8 only in the provision of two cut-outs 160 provided in the
tie-member 110 which serve the purpose of facilitating breaking of
the seal without the need of scissors or a tool and of assuring
that the seal breaks in the strap. Additionally, these cut-outs
serve as further intentionally weakened places to break in case of
tampering with the seal.
In addition to the intentionally weakened places so far described,
other intentionally weakened places may also be provided either in
addition to those described or in lieu thereof. For example, a
semi-circular hole 126 (FIGS. 6 and 9) may be provided in or behind
the shoulder 124 or in a shoulder forming the equivalent of stop 24
which can be made of such a diameter that the strap 10 or 110
breaks in this weakened area before it breaks at 22 or 122.
Furthermore, any other suitable additional weakening means may be
provided to suit the particular design requirements.
In all embodiments, the smallest diameter of the tapering section
22 or 122 is so chosen, taking into consideration the plastic
material used, that any forcible attempt to withdraw the head 20 or
120 out of the socket would result in a breaking off of the
connection between the head portion 21 and the adjoining end of the
tapering section before there is any substantially yielding and/or
possible destruction of the locking fingers of the socket, thus
further ensuring the safety of the seal. Of course, in the presence
of other weakened sections, such as at 126 and/or at 160, the seal
may also break at this place or these places, or at any other
intentionally weakened place before it breaks at 22 or 122.
It will be readily recognized from the above that the seal
according to the present invention can be manufactured by a single
operating step without requiring any after treatment, yet offering
a substantially completely tamper-proof structure. Any known
suitable synthetic resinous material may be used for the plastic
seal of the present invention and any suitable known molding
techniques may be used for the purpose of molding the same.
While I have shown and described only several embodiments in
accordance with the present invention, it is understood that the
same is not limited thereto, but is susceptible of numerous changes
and modifications as known to those skilled in the art. For
example, the body 30 and 130 may be modified in shape and/or may be
even omitted, leaving only a housing of suitable shape, to which
the tie-member would then be connected in an appropriate manner.
Additionally, other cross-sectional configurations may be used for
the various parts of the seal such as the tie-member and/or the
head, as well as the socket. Furthermore, a shoulder similar to
shoulder 124 may be used in lieu of stop 24. Thus, it is obvious
that the present invention is not limited to the details shown and
described herein, and I therefore do not wish to be limited to the
same, but intend to cover all such changes and modifications as are
encompassed by the scope of the appended claims.
* * * * *