U.S. patent application number 13/499066 was filed with the patent office on 2012-09-27 for plastic closure comprising a cutting and perforating device.
This patent application is currently assigned to ROBERT BOSCH GMBH. Invention is credited to Dan Barron.
Application Number | 20120241471 13/499066 |
Document ID | / |
Family ID | 42799681 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120241471 |
Kind Code |
A1 |
Barron; Dan |
September 27, 2012 |
PLASTIC CLOSURE COMPRISING A CUTTING AND PERFORATING DEVICE
Abstract
The invention relates to a closing device (1) consisting of a
plastic material for applying to a closed container consisting of a
plastic film material. Only two cutting teeth (20, 21) of the same
height are to be applied to the cylindrical perforator (5) of said
device, said teeth being arranged in an angular region of between
70.degree. and 120.degree. of the circumference. In this way, the
section of the subsequent tooth extends into the section of the
previous tooth, enabling a secure opening, without the risk of
cutting an entire rondelle out of the plastic film of the
container. The creation of only two partial sections without
producing an opening in the container is also prevented.
Inventors: |
Barron; Dan; (Schaffhausen,
CH) |
Assignee: |
ROBERT BOSCH GMBH
Stuttgart
DE
|
Family ID: |
42799681 |
Appl. No.: |
13/499066 |
Filed: |
September 15, 2010 |
PCT Filed: |
September 15, 2010 |
PCT NO: |
PCT/EP10/63560 |
371 Date: |
June 12, 2012 |
Current U.S.
Class: |
222/83 |
Current CPC
Class: |
B65D 5/748 20130101 |
Class at
Publication: |
222/83 |
International
Class: |
B65D 5/74 20060101
B65D005/74 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2009 |
DE |
10 2009 045 124.2 |
Claims
1. A closing device (1) made of a plastic material for applying to
a closed container made of a plastic film material, wherein said
closing device comprises a lower part (2) having a cylindrical
outlet (6) and a flange (3) for attaching to the container and a
screw cap (4) which is screwably fixed to the lower part (2) as
well as a cylindrical perforator (5) having an external thread,
which is open on both sides in an axial direction and travels in an
internal thread in the outlet (6) of said lower part (2), wherein
means (44) are located in the screw cap (4) which during initial
unscrewing movement of said screw cap (4) move the perforator (5)
downwards in a helical manner and wherein said cylindrical
perforator (5) has cutting teeth on a cylindrical wall thereof at
the end which when mounted is directed towards the container wall,
characterized in that said perforator has exactly two cutting teeth
of the same height, both of which are arranged in an angular region
of between 70.degree. and 120.degree. of a circumference.
2. The closing device according to claim 1, characterized in that a
wall thickness of the two cutting teeth is thicker than a wall
thickness of a cylindrical jacket wall of the perforator.
3. The closing device according to claim 1, characterized in that a
steepness of the external thread (12) of the perforator (5) and the
internal thread (18) of the outlet (6) is selected in such a way
that during the unscrewing movement of the screw cap (4), a tooth
moving in a cutting direction travels through a maximum cutting
distance of 210.degree. from a point of contact on the plastic film
of the container up to a point where the unscrewing movement of
said screw cap has completely ended.
4. The closing device according to claim 1, characterized in that
the external thread of the outlet is a double-start fine-pitch
thread.
5. The closing device according to claim 1, characterized in that
the external thread of the perforator and the internal thread of
the outlet have a trapezoidal thread profile.
6. The closing device according to claim 1, characterized in that
at least one of the two cutting teeth (20, 21) has a number of
staggered succeeding teeth (24), which are arranged at different
heights in a descending step-like succession, so that depending
upon a penetration depth of the perforator into the film to be cut,
one succeeding tooth after the other is operative and wherein a
swarf receiving space (25) is located in each case between the
respective foremost cutting tooth (20, 21) and the next operative
succeeding tooth as well as between two adjacent succeeding
teeth.
7. The closing device according to claim 6, characterized in that
the swarf receiving spaces (25), which are operative at first, are
larger than the swarf receiving spaces which are subsequently
operative.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a closing device consisting
of a plastic material for applying to a closed container consisting
of a plastic film material, wherein said closing device comprises a
lower part with a cylindrical outlet and a flange for attaching
same to the container and a screw cap which is screwably fixed to
the lower part. Said closing device further comprises a cylindrical
perforator having external thread, which is open to both sides in
the axial direction and travels in the outlet of the lower part, in
the internal thread thereof, wherein means are located in the screw
cap, which move the perforator downwards in a helical manner during
the initial unscrewing movement of said screw cap and wherein said
cylindrical perforator has cutting teeth on the cylindrical wall
thereof at the end which is directed towards the container
wall.
[0002] Closing devices of the type previously mentioned have to
date only been applied to containers produced from laminated film
material. These laminated films comprise at least three layers of
different types of material. First of all, such a film consists of
a cardboard layer, which provides the container with the necessary
rigidity, an aluminum layer serving as an aroma barrier and a
plastic layer which ensures the required denseness. In order to
separate these three layers, the corresponding perforator of the
aforementioned closing device must fulfill various functions. A
plurality of saw teeth are often recommended for separating the
cardboard layer, wherein a raised tooth cuts through the aluminum
layer with a forward cutting edge and wherein a perforating tooth
breaks through the plastic layer before the aforementioned cutting
edge can continue to cut the plastic film. In the case of these
containers consisting of laminated film material, the separation of
the cardboard material generally represents a problem. Particularly
if the partial press cut, which serves as a support and at least
separates the cardboard layer to some extent, does not exactly
correspond to the cutting line of the perforator, the teeth are
then either too weak or in the case of a considerable number of
teeth, the cardboard material comes between the teeth and said
teeth can thereafter hardly produce a perforating effect.
SUMMARY OF THE INVENTION
[0003] The present invention relates, however, to a closing device,
which is applied to a pure plastic film material. Such tubular
receptacles, mostly referred to as pouches in the technical
language, have not been opened to date by means of the
aforementioned closing devices. On the contrary, an opening was
already punched out and a closure including the outlet thereof was
welded on the pouches so as to be correctly positioned or was
shrink-wrapped between two film layers. Because the shelf-life of
the filled food material or beverage is thereby solely dependent
upon the impermeability of the closure, such closures were
virtually used only in unproblematic areas, particularly in the
area of cosmetics.
[0004] When using a closing device of the kind mentioned at the
beginning of the application, the container pouch remains
completely closed until the point of first being opened. An
increased shelf-life is thereby provided. In addition, the plastic
film in such applications according to the invention is
substantially more robust and is designed having a greater wall
thickness than the very thin plastic film layer in the case of a
laminated film. This in turn gives rise to other demands being
placed on the closing device. Initial trials with closing devices
from prior art did not produce any reliable results.
[0005] Perforators as, for example, from the American patent
publications U.S. Pat. No. 5,020,690 or U.S. Pat. No. 5,141,133
comprise a plurality of teeth. These teeth abutting one another
basically form the shape of an annular saw blade. Such solutions
have either led to a rondelle being completely cut out of the
plastic film and falling into the container or as a result of the
toughness of the film to individual teeth being broken off and
falling into the container. Because the containers involved here
typically relate to containers for beverages, this is totally
unacceptable.
[0006] It has been assumed up until now that a plurality of teeth
is advantageous because a plurality of perforations thereby arise.
It has, however, actually been determined that a plurality of
perforations do not provide an advantage per se. It has in fact
been shown, that a plurality of teeth automatically leads to these
teeth having to be relatively weak. This leads to the disadvantage
previously mentioned above.
[0007] Based on this realization, further developments have
accordingly been put into place, in which on the one hand the
number of teeth was reduced and on the other hand the shape of the
teeth was variably configured. A solution is therefore known, for
example, from the European patent publication EP-A-1415926 having
equally high teeth, which, however, are distributed over the
periphery in a non-uniform manner. In addition, a closing device of
the type mentioned at the beginning of the application is known
from the American patent publication U.S. Pat. No. 6,279,779 having
a perforator which comprises only a single tooth. This tooth is
designed in a suitably strong manner and has different surfaces
with a different effect. The one-tooth version has definitely not
proven its worth. The procedures for severing the film as well as
the perforation thereof, the subsequent cutting of the complete
material and finally the folding away of the cut-out part have not
been able to be optimized in a single element. The applicant
therefore conducted trials with a perforator according to the WIPO
patent publication WO2007/030965, wherein three teeth are present,
which are distributed over the periphery and are minimally offset
from a uniform distribution. Even though perforators of this type
have proven their worth in many instances, cases frequently occur
in which either the film is completely cut out and the
corresponding rondelle fell into the receptacle or in other cases
the films were cut only at three locations to an approximately
equal width and the film remained hanging in an occluding manner
over the opening. Based on these realizations, the applicant
undertook elaborate trials to find an optimal solution, which
reliably implements an opening incision in such a way that a
flap-like rondelle, which stays in contact with the receptacle,
remains hanging, said rondelle also being pushed out of the open
area of the perforator by the teeth.
[0008] A closing device of the kind mentioned at the beginning of
the application meets this aim, wherein said device is
characterized by having exactly two equally high teeth which are
arranged in an angular region of between 70.degree. and 120.degree.
of the circumference. This has the effect that the plastic film to
be cut open is pre-tightened by the two teeth and that said teeth
subsequently begin to perforate and cut the film. After a short
distance, the subsequent tooth then extends into the cutting area
of the previous tooth and is thereby rendered inoperative. If the
perforation of the film occurs virtually immediately upon first
contact, the film still cannot completely be annularly cut out and
consequently a plastic film rondelle does not fall into the
container. If the perforation and the following incision occur
relatively late, a sufficiently long incision is still produced,
which ensures that the section of the subsequent tooth runs into
the area of the section of the previous tooth and as a result a
section is still achieved, which extends more than 180.degree.;
thus enabling the film to be cut open sufficiently wide to achieve
a sufficient flow rate.
[0009] As previously mentioned, the closing device according to the
invention is applied to a container consisting of a pure plastic
film material. This one or multiple layer plastic film is
substantially thicker than the plastic film which is used as an
impermeability layer in the composite film consisting of diverse
materials.
[0010] Whereas in the case of the thin film, wherein the
perforation must foremost be done to ensure a reliable opening on
account of the high elasticity of said film, this appears to no
longer play a central role in the case of the film now being used.
Experiments observed at a strong magnification have shown that
apparently the film is slit open while forming swarf.
[0011] In light of this evidence, it is therefore an additional aim
of the present invention to equip the teeth with swarf control
means as in the case of a steel processing cutting plate. In
solutions from prior art, this swarf has actually accumulated on
the tooth tip and the torque output applied by means of said prior
art was thus substantially higher than is the case with the now
present solution.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] A preferred exemplary embodiment of the subject matter of
the invention is depicted in the drawings and subsequently
described. In the drawings:
[0013] FIG. 1 shows the closed plastic closure prior to initial use
in a side view and
[0014] FIG. 2 shows the same in a diametral vertical section
[0015] FIG. 3 shows in a simplified depiction the perforator from
below with a view of the edge having the two cutting teeth
[0016] FIG. 4 shows the perforator and the lower part with a flange
as a one-piece subassembly prior to assembly, again in a diametral
vertical section and
[0017] FIG. 5 the same view rotated 180.degree..
[0018] FIG. 6a-6c show various sectional views.
[0019] FIG. 7 shows a perforator suitable for harder plastic films
comprising two teeth which are offset at an angle and have
different cutting characteristics and
[0020] FIG. 8 shows the same perforator rotated 120.degree..
[0021] FIG. 9 shows a load-time diagram for the perforator
according to the FIGS. 7 and 8, whereas
[0022] FIG. 10 shows such a load-time diagram for the perforator
having the tooth configuration according to the FIGS. 4 and 5.
DETAILED DESCRIPTION
[0023] The plastic closing device is denoted in its entirety with
the numeral 1. Said device comprises three components, of which two
can be produced as one piece resulting from the manufacturing
processes thereof, as is subsequently described in FIGS. 4 and 5.
Said plastic closing device 1 comprises a screw cap 4, on the lower
edge of which a tamper evidence band 7 is molded via predetermined
breaking point bridges so as to align with the jacket wall of the
screw cap. In the side view according to FIG. 1, only a flange 3,
which is a part of the lower part 2, of the closing device 1 can be
seen.
[0024] In the cross-sectional view according to FIG. 2, it can be
seen that the screw cap 4 has a jacket wall 9 as well as a top
surface 10. Said screw cap 4 has internal screw thread 11 which is
designed as fine-pitch-pitch thread. The lower part 2 including the
flange 3 thereof, which serves as a welded or glued connection to
the container, comprises a cylindrical outlet 6, which is tubular
and open to both sides. This outlet 6 has external thread 12 which
is also designed as fine-pitch thread and meshes with the internal
thread 11 of said screw cap 4 when said screw cap 4 is screwed on
and off. The fine-pitch thread 11, 12 is preferably designed as a
double-start thread. The fine-pitch thread has the advantage of
easy assembly due to the internal thread of the said screw cap
being able to be pushed over the external thread 12 of the outlet 6
in a ratchet-like manner. This allows for assembly without a
relative rotation of the parts with respect to one another. Two
driving elements 13 diametrically opposed to one another are
located in said screw cap 4, wherein said driving elements are
integrally formed with the bottom side of the top surface 10 of
said screw cap 4. Said driving elements 13 act together with the
driving element 14 in the perforator 5. Said perforator 5 is
subsequently described in detail with the aid of FIGS. 4 and 5.
[0025] As previously described, the perforator 5 and the lower part
2 are manufactured as one piece, just as is depicted in FIG. 4. In
this case, said lower part 2 and said perforator 5 together form a
subassembly, which can be manufactured using a single injection
mold. During assembly, said lower part 2 and said perforator 5 can
simply be pushed together. In so doing, said perforator 5 comes to
rest completely within the cylindrical outlet 6. In this position,
said perforator 5 is integrally formed as a subassembly on the
upper edge of the outlet 6 via predetermined breaking points. Said
perforator 5 consists of a cylindrical pipe section 16, which has
course thread 17 on the outside. Said course thread 17 having a
large pitch meshes with a correspondingly adapted trapezoidal
thread 18 on the inside of the outlet 6. Said perforator 5
additionally comprises two entraining ribs 19 which are
diametrically opposed to one another and on which the
aforementioned driving elements 13 of the screw cap 4 make contact
during the respective screwing movement. Two cutting teeth are
integrally formed on the lower edge of said perforator 5. Both of
said teeth can be seen in FIG. 2, whereas in FIG. 5 only the
subsequent tooth can be seen while the leading tooth has been cut
away. Said leading tooth is denoted with the reference numeral 20
and said subsequent tooth with the reference numeral 21. Both teeth
20, 21 have the same length l. This length designates the vertical
distance from the lower edge 22 of the cylindrical pipe section 16
to the tip of the corresponding cutting tooth.
[0026] In the assembled state as is shown in FIG. 2, the perforator
5 completely lies within the cylindrical outlet 6. The tip or
rather the two tips of the cutting teeth 20, 21 lies at the height
of the lower edge of the flange 3 of the lower part 2. When the
screw cap 4 is unscrewed, said perforator 5 moves axially in the
opposite direction, wherein said perforator carries out a
substantially larger translational vertical travel per rotation
than said screw cap 4 in the opposite direction. Said perforator 5
actually carries out maximally a rotary motion of around
approximately 330.degree., whereas said screw cap goes through one
or several turns until being completely unscrewed.
[0027] Depending upon strength, elasticity and other factors, in
particular with regard to the pre-tightening force on the plastic
film of the pouch receptacle, the plastic film is sooner or later
perforated. Said film is practically always perforated
simultaneously by the cutting teeth 20, 21. The sectional views as
depicted in FIGS. 6a to c thus arise. In FIG. 6a, the partial
sections of the subsequent tooth have not yet advanced into the
section of the leading (previous) tooth. On the other hand in FIG.
6B, this has already happened. This figure shows the cutting line
obtained in the worst case, which lies in the magnitude of 200 to
240.degree.. Were this the end position, the leading (previous)
tooth would basically push the flap-like part L downwards so that
also in this case, the passage is open more than 50%. The cutting
line normally extends about a partial circle of around 330.degree..
This situation is depicted in FIG. 6c.
[0028] In FIG. 3, the perforator 5 is depicted in a simplified form
with a view of the teeth in the direction of the rotational axis of
the cylindrical pipe section 16. If radii are drawn from tooth tips
to the center of the longitudinal axis, an angle .alpha. is then
formed between them. Said angle .alpha. must be within an angular
range between 70.degree. and 120.degree.. In addition, it is
advantageous if the steepness of the external thread of the
perforator 5 and the internal thread 18 of the outlet 6 are
selected in such a way that during the unscrewing movement of the
screw cap 4, the cutting teeth 20, 21 travel through a maximum
cutting distance of 210.degree. in the cutting direction from the
point of contact on the plastic film of the container to be severed
up until said unscrewing movement of said screw cap 4 has
completely ended. If the maximum angle, which the leading tooth 20
and the subsequent cutting tooth 21 enclose together, namely an
angle of 120.degree., is now added to the 210.degree., this then
results in a maximum cutting line which extends over 330.degree.. A
sufficient connection between the plastic film of the container and
the aforementioned flap L thereby remains. If the worst case is
assumed, that the perforation of the film first occurs after a
quarter turn, i.e. after 90.degree., and the angle between the two
cutting teeth amounts to only 70.degree., said leading tooth still
implements a minimum cutting line of 120.degree. while said
subsequent tooth 21 travels through the additional 70.degree.; thus
enabling a cutting line of over 180.degree. also to be formed in
the worst case.
[0029] Because the resulting forces on the cutting teeth are
substantially greater in this version than in the case of a
plurality of small teeth, it is advantageous for the wall thickness
of the cutting teeth 20, 21 to be selected to be larger than the
wall thickness of the cylindrical pipe section 16 of the
perforator. This can be seen most clearly in FIG. 5. This does not
appear to be the case in FIG. 4; however, this is merely due to the
fact that the cutting line travels in this instance through the
entraining ribs 19.
[0030] It is known that plastic films can be obtained in many
different qualities. Said films differ not only in the selection of
the plastic materials used but also in thickness, stiffness,
hardness, etc. With regard to the production of pouch receptacles,
which are to have a comparable strength to those consisting of
multilayered laminates comprising cardboard, such plastic films
cannot be reliably opened with the plastic closing devices known to
date. The stronger the film being used was, the greater the
thickness of the teeth had to be, and in doing so the films could
hardly be opened without too high of a torque being required for
the operation, which then users could not be expected to produce.
The pouch receptacles were in fact entirely manufactured from this
relatively thick and hard material, wherein, however, an opening
was press cut and sealed with a film section, which was
substantially softer and could be cut with the usual plastic
closing devices known until that time. The plastic closing device
was in turn welded to the film section.
[0031] The trend is to move away from this technology and it has
been shown that this is possible if the leading as well as the
subsequent tooth is designed in the manner depicted in FIGS. 7 and
8. Whereas emphasis was especially placed on a perforation of the
film when using the teeth from prior art, weight is now placed on
the cutting of the film. In the case of the softer plastic films, a
much stronger stretching occurs and accordingly it was essential
for the two teeth to make contact at approximately the same time
and thereby to tighten the film so that a perforation takes place.
After that, the film itself could subsequently be cut practically
without resistance along the cutting edge of the corresponding
teeth. This process is, for example, depicted in the time-load
diagram according to FIG. 10. FIG. 9, on the other hand, shows the
load-time diagram of the perforator according to FIGS. 7 and 8
comprising the new tooth configuration. Both curves cannot be
directly compared when considering the fact that a thin,
substantially more elastic film is cut in the case depicted in FIG.
10 whereas a thicker film, which is substantially harder but less
elastic, has been cut in the diagram according to FIG. 9.
[0032] It can be seen in FIG. 10 that the torque increases more
slowly up until the point in time of the perforation by a first of
the two teeth, whereupon the torque immediately drops until the
second tooth begins to have an effect and then subsequently falls
very sharply.
[0033] In contrast thereto, when severing the thicker film using
the perforator comprising the newly designed teeth shapes, the load
which has to be applied increases faster until the maximum pressure
occurs on the film and the cutting action begins. The load now
continuously decreases until the first succeeding tooth begins to
have an effect and the additional effect of the further succeeding
teeth can then additionally be seen in the region where the drop in
load occurs. Despite the substantially harder film, the required
force output remains practically the same. This astonishing result
is due to the fact that the thicker film hardly ever tears but has
accordingly to be cut much more, wherein the cutting
characteristics resemble a cutting plate of a lathe tool. It can be
microscopically determined that swarf forms at the same time the
plastic is cut, and this swarf must be able to be routed into an
area away from the teeth in order to prevent said swarf from moving
in front of the actual cutting point of the teeth and thereby
substantially increasing the torque.
[0034] A preferred exemplary embodiment of these newly configured
teeth of a perforator is explained below with the aid of FIGS. 7
and 8. The perforator in its entirety is denoted with the reference
numeral 5. This too comprises a cylindrical pipe section 16, on the
outside of which a coarse thread 17 is molded. The trapezoidal
thread 18 then engages in said coarse thread 17 in the cylindrical
outlet 6. The cylindrical section 16 is equipped on the inside with
entraining ribs 19. In this option, the cylindrical section 16 is
reduced in diameter in the lower cutting region 26 by approximately
the depth of said coarse thread 17. Provision is made in turn at
the lower edge of this tapered cutting region 26 for a leading
cutting tooth 20 and a subsequent cutting tooth 21. Whereas in the
previously described option of this cutting tooth, a straight,
relatively steep cutting surface is present in the leading position
in the cutting direction, this leading cutting edge is in this case
tiered; and there is a plurality of succeeding teeth 24, which are
tiered at different heights, arranged in a staggered manner.
Depending upon the penetration depth, said succeeding teeth 24 are
employed one after the other A swarf receiving space 25, which runs
approximately arcuately, is situated between in each case the
foremost leading and subsequent cutting tooth 20, 21 and the
cutting tooth 24 disposed in the leading position in the cutting
direction. Such a swarf receiving space 25 is also in each case
situated between two succeeding teeth 24 arranged adjacently in
each case. This can be seen most clearly in FIG. 7.
[0035] In contrast to the solution first shown, wherein the teeth
perform practically only a perforating action by means of a
perforating tip 23 and thereafter the leading cutting edge 28 comes
into operation, the two main teeth, namely the leading cutting
tooth 20 and the subsequent cutting tooth 21, as well as the
staggered succeeding teeth 24 all work in this case the same and
have altogether a swarf-removing cutting effect. After the leading
tooth and the subsequent tooth 20, 21 have come through the film, a
succeeding tooth 24 must therefore take on their function. Said
succeeding teeth are therefore disposed according to height in a
descending step-like succession on account of the perforator 5
penetrating ever deeper into the container to be cut open during
the screwing action. Said succeeding teeth also operate in a
swarf-removing manner and thus said succeeding teeth are also
equipped in each case with a respective swarf receiving space 25.
It is appropriate for the swarf receiving spaces 25 which operate
first to be larger that the swarf receiving spaces that
subsequently become operative.
* * * * *