U.S. patent application number 10/513551 was filed with the patent office on 2006-05-25 for manufacture of bottle with push-on closure.
Invention is credited to Charles Jonathan Britton.
Application Number | 20060108315 10/513551 |
Document ID | / |
Family ID | 9936187 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060108315 |
Kind Code |
A1 |
Britton; Charles Jonathan |
May 25, 2006 |
Manufacture of bottle with push-on closure
Abstract
A method of manufacture of a bottle which may be closed by a
push-on closure, apparatus for manufacturing the same, a bottle and
a closure for the bottle. A bottle is manufactured in a
multi-component assembly. The bottle preform (not shown) is made by
an injection molding technique, having detents on its upwardly and
outwardly facing surfaces. It is then transferred to a blow mould
where it is first heated, and then shaped by inserting a blow pin
through the neck of the preform to stretch it in its longitudinal
axis. During this operation, the top surface of the preform is bent
down, such that the detent formed on the upwardly facing surface of
the preform now extends laterally into the volume of the preform.
The stretched preform is then blown to take the shape of the blow
mould, forming the bottle. A closure is formed by injection
moulding, and is held on the bottle by the laterally extending
detents.
Inventors: |
Britton; Charles Jonathan;
(Tewkesbury, GB) |
Correspondence
Address: |
FLYNN THIEL BOUTELL & TANIS, P.C.
2026 RAMBLING ROAD
KALAMAZOO
MI
49008-1631
US
|
Family ID: |
9936187 |
Appl. No.: |
10/513551 |
Filed: |
May 6, 2003 |
PCT Filed: |
May 6, 2003 |
PCT NO: |
PCT/GB03/01911 |
371 Date: |
June 20, 2005 |
Current U.S.
Class: |
215/321 ;
215/43 |
Current CPC
Class: |
B29B 2911/1442 20130101;
B65D 41/185 20130101; B29C 49/06 20130101; B29C 49/58 20130101;
B29C 49/4802 20130101; B65D 1/0246 20130101; B29C 49/4242
20130101 |
Class at
Publication: |
215/321 ;
215/043 |
International
Class: |
B65B 7/28 20060101
B65B007/28; B65D 41/16 20060101 B65D041/16; B65D 41/22 20060101
B65D041/22 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2002 |
GB |
0210398.4 |
Claims
1. A method of making a bottle having a body and a rim defining an
opening for the bottle, the opening being capable of being closed
by a push-on closure, the bottle being made of a material which is
susceptible to deformation when heated, the method comprising the
steps of: injection moulding in an injection moulding apparatus a
preform in the shape of a closed-end tube with a rim at its mouth,
the rim comprising an outward generally-radial flange having an
upper surface and a lower surface, a first detent simultaneously
formed with the flange as an upstanding projection from the upper
surface of the flange towards the radially inner end thereof, and a
second radically-outward detent formed at the outer edge of the
flange, the tube depending from the radially-inner edge of the
flange; placing the preform in a pressure moulding apparatus at an
elevated temperature with the preform being located at least in
part by means of the second detent; moving the flange and the first
detent downwardly and outwardly relative to the second detent so
that the upper surface of the flange now faces inwardly and the
first detent projects inwardly into the opening for the bottle,
whereby a closure can be push-fitted onto the rim of the bottle to
engage both the first inwardly-facing detent and the second
outwardly-facing detent; and expanding the tube under pressure to
form the body of the bottle.
2. A method according to claim 1, in which the moving step is
caused at least in part by means of a portion of a core of the
pressure moulding apparatus bearing against the upper surface of
the flange and/or the first detent.
3. A method according to claim 1, in which the moving step is
caused at least in part by differential pressure applied between
the interior of the preform and the exterior.
4. A method according to claim 1, in which the moving step is
caused at least in part by downward stretching applied to the tube
portion of the preform.
5. A method according to claim 1, further comprising the step of
longitudinally stretching the tube portion of the preform.
6. A method according to claim 1, further comprising the step of
applying differential pressure between the interior of the preform
and the exterior to expand the tube portion to form the body of the
bottle.
7. A method according to claim 1, in which the preform is formed
with an upwardly-extending sealing portion extending above the
second detent in the rim portion.
8. A method according to claim 1, in which the rim includes a
downward flange depending from the outer end of the radial
flange.
9. A method according to claim 8, in which in the moving step the
lower surface of the radial flange moves into homogeneous contact
with the downward flange.
10. A method according to claim 1, in which the first detent
extends continuously around the mouth of the preform.
11. A method according to claim 1, in which the second detent
extends continuously around the mouth of the preform.
12. A method according to claim 1, in which the material is seleted
from the groups comprising polyethylene terephthalate, polyethylene
naphthalate and co-polymers and blends thereof.
13. A method according to claim 1, further comprising the steps of
filling the bottle with liquid, and push-fitting a closure to the
bottle, in which the closure includes first and second engaging
portions for engaging respectively with the first and second
detents to secure the closure on the bottle.
14. A method according to claim 13, in which the first and/or the
second engaging portions are discontinuous around the closure.
15. Apparatus for making a bottle having a body and a rim portion
defining an opening for the bottle, the opening being capable of
being closed by a push-on closure, the apparatus comprising:
injection moulding apparatus shaped and arranged to produce a
preform in the shape of a closed-end tube with a rim at its mouth,
the rim comprising an outward generally-radial flange having an
upper surface and a lower surface, a first detent upstanding from
the upper surface of the flange towards the radially inner end
thereof, and a second radially-outward detent at the outer edge of
the flange with the tube depending from the radially-inner edge of
the flange; and pressure moulding apparatus having mould parts
defining a mould cavity and comprising means to locate the preform
in the mould cavity with the second detent in a fixed location
therein, means for moving the flange and the first detent
downwardly and outwardly relative to the second detent such that
the upper surface of the flange faces inwardly and the first detent
projects inwardly into the opening for the bottle, and means for
applying a pressure differential between the interior of the tube
and the extension to expand the tube into contact with the mould
parts defining the mould cavity.
16. A bottle made of a material which is susceptible to deformation
when heated, the bottle comprising a body portion and a rim
portion, the rim portion being narrower than the body portion and
providing an opening constituting the mouth of the bottle, the rim
portion including an inwardly-facing detent facing into the opening
and an outwardly-facing detent facing radially outwardly and a
portion between the detents for constituting a sealing region, and
the bottle being provided with a sealing closure, the closure
having a peripheral trough defined between inner and outer
cylindrical flanges, the inner cylindrical flange carrying means
for engaging the inwardly-facing detent and the outer cylindrical
flange carrying means for engaging the outwardly-facing detent, the
closure further comprising a sealing portion in the trough for
sealing engagement with the sealing region of the rim portion of
the bottle.
17. A bottle made of a material which is susceptible to deformation
when heated, the bottle comprising a body portion and a rim
portion, the rim portion being narrower than the body portion and
providing an opening constituting the mouth of the bottle, the rim
portion including an inwardly-facing detent facing into the opening
and an outwardly-facing detent facing radially outwardly, a portion
between the detents being adapted to constitute a sealing
region.
18. A closure for use with the bottle of claim 17, the closure
having a peripheral trough defined between inner and outer
cylindrical flanges, the inner cylindrical flange carrying
engagement means for engaging the inwardly-facing detent on the
bottle and the outer cylindrical flange carrying engagement means
for engaging the outwardly-facing detent on the bottle, and a
sealing portion in the trough for sealing engagement with the
sealing region of the rim portion of the bottle.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a method of manufacturing a bottle
which can be closed by a push-on closure, to apparatus for
manufacturing the bottle, to a bottle and to a closure for the
bottle. The invention is particularly though not exclusively
suitable for use with bottles made of PET or PEN thermoplastic
materials.
[0002] Beer drinkers throughout the world are familiar with the
so-called crown cap, which is a metal cap used with glass beer
bottles to provide an effective seal and which is applied by a
crimping action and removed by a simple tool which engages under
the edge of the rim of the cap to bend the cap up and lever it off
the bottle. Metal crown caps are very effective but require a glass
bottle and can not be used with plastics bottles, particularly made
of PET or PEN. There is a need for a simple push-fit closure
arrangement as an alternative to the crown cap.
[0003] PET bottles with screw tops are known but these do not have
the same desirable properties for use with fermented or carbonated
gaseous drinks as do crown caps. An example of the manufacture of a
PET bottle with a screw top is described in International Patent
Application WO97/19806. In that manufacture an embryo container is
formed by injection moulding. The embryo container comprises a
closed-end tube which will form the body of the bottle with an
outward radial flange at its mouth. Part of the upper surface of
the flange is formed with a spiral, which will form a screw thread.
The embryo container is transferred to a stretch/blow moulding
machine where pressure is applied to its interior, forcing the
radial flange downwardly and outwardly so that the upper surface of
the flange becomes the inner cylindrical surface of the mouth of
the bottle with the screw thread formed in it.
[0004] Other methods for forming PET bottles are described for
instance in U.S. Pat. No. 5,126,177 (Stenger) and U.S. Pat. No.
5,501,590 (Orimoto et al.).
[0005] None of the prior art however provides a means for making a
bottle with a push-on closure which can be employed with a plastics
bottle and/or closure without the need to use a crimped metal crown
cap and yet which retains the advantages of the crown cap.
SUMMARY OF THE INVENTION
[0006] The invention is defined in the independent claims below to
which reference should now be made. Advantageous features are set
forth in the appendant claims.
[0007] A preferred embodiment of the invention is described in
detail below with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will now be described in more detail, by way
of example, with reference to the accompanying drawings, in
which:
[0009] FIG. 1 is a sectional view showing the injection moulding of
a preform used in manufacturing a plastics bottle in an embodiment
of the invention;
[0010] FIG. 2 is a sectional view of the preform obtained from the
injection moulding operation;
[0011] FIG. 3 is a sectional view showing the shape of the rim of
the preform in more detail;
[0012] FIG. 4 shows the preform when transferred to a pressure or
blow moulding machine;
[0013] FIG. 5 shows the preform as in FIG. 4 with the blow core now
in place;
[0014] FIG. 6 shows the preform with the stretching rod partially
descended and with the blow core bearing against the inside of the
rim of the preform;
[0015] FIG. 7 is a detail sectioned view of the rim of the bottle
and the part of the blow core which bears against it before
pressure is applied to the rim;
[0016] FIG. 8 is a view similar to FIG. 7 showing the rim partially
distorted by the blow core;
[0017] FIG. 9 is a view similar to FIG. 7 showing the rim with its
final condition with the blow core fully descended;
[0018] FIG. 10 shows the stretch rod fully descended;
[0019] FIG. 11 shows the bottle in the blow moulding apparatus when
the bottle has been blown under pressure;
[0020] FIG. 12 is a sectional view of the resultant bottle when
removed from the mould;
[0021] FIG. 13 is a detail showing the shape of the rim of the
finished bottle more clearly;
[0022] FIG. 14 is a top view of the bottle cap;
[0023] FIG. 15 is a side sectional view of the cap;
[0024] FIG. 16 is a sectional detail of part of the cap;
[0025] FIG. 17 is a detail view of part of the cap taken on the
arrow A in FIG. 14;
[0026] FIG. 18 is a detail sectional view showing the cap on the
bottle; and
[0027] FIG. 19 is a side view of the finished bottle with the cap
on it.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] The method of making a preferred embodiment of the invention
and a preferred apparatus for making it, together with the
resultant bottle and a closure for the bottle will now be described
in detail by way of example.
[0029] The bottle is made by an essentially two-stage process.
Stage one involves injection moulding in an injection moulding
machine a preform. This preform is then transferred to a pressure
moulding machine where it is pressure moulded at an elevated
temperature to form the final shape of the bottle. When placed into
the pressure moulding apparatus the preform is deformed to form the
rim of the bottle, and the body of the bottle is formed by blowing.
Finally, the bottle is associated with a corresponding push-on
closure which, after filling of the bottle, can be push-fitted to
the rim of the bottle.
[0030] The bottle is made of a material which is susceptible to
deformation when heated. This could be glass. However, the
invention is particularly suitable for making bottles out of
certain plastics materials, particularly thermoplastics. Materials
such as polyethylene terephthalate (PET), polyethylene naphathalate
(PEN), and co-polymers and blends of these two materials, in both
crystalline and a amorphous form, could be viable.
[0031] The first stage in the manufacture is illustrated in FIG. 1.
This figure shows a section through an injection moulding machine
in which the preform has just been formed by injection moulding.
The preform is shown at 20. The mould consists of a cavity insert
12, a cavity insert carrying block 14 surrounding and supporting
the cavity insert 12, neck splits 16 supported by a neck split
carrying plate 18 and an injection core 22. The preform 20 is
formed in the cavity between the cavity insert 12 and the injection
core 22, with the outer edge of the rim being defined by the neck
splits.
[0032] The shape of the cavity is such that the preform is
generally in the shape of a closed-end tube which tapers slightly
towards its closed end, and has a rim at the open end of the tube
and defining the opening or mouth of the bottle. The tubular part
of the preform will eventually be expanded to form the body of the
bottle. At this stage the outer surface and the inner surface of
the preform both taper slightly towards the closed end of the tube,
being defined by the inner mould surface of the cavity insert 12
and the outer mould surface of the injection core 22, respectively.
The plastics is injected through an appropriate orifice 24 in the
cavity insert 12, at the bottom end of the tube.
[0033] The rim section of the preform which is to form the mouth of
the bottle and surrounds the opening to the tubular section of the
preform is described in more detail below.
[0034] The injection moulding apparatus is provided with
appropriate cooling channels around the cavity insert 12, and a
cooling tube 26 extends into the interior of the injection core 22
so as to cool the mould core portion within the tubular part of the
preform 20. In other respects the injection moulding machine is
conventional.
[0035] When sufficiently solid the preform is then removed from the
injection moulding apparatus. This is achieved by retracting the
injection core 22, and slightly retracting the neck splits 16 on
the neck split carrying plate 18. The preform can then be removed
from the mould, if necessary with the application of some pressure
from the bottom through the injection orifice 24.
[0036] The resultant preform is shown in FIGS. 2 and 3. FIG. 2
shows the overall shape of the preform 20. The closed-end tube 28
forms the greater part of the length of the preform, and terminates
at the rim portion 30. The rim portion is more clearly shown in
FIG. 3, which is a detail sectional view through one part of the
periphery of the rim 30. Here will be seen the upper part of the
wall section of the tube 28 which is to form the eventual wall of
the body of the bottle. On the top of the wall section 28 there is
a transverse or annular flange 32 extending outwardly from the top
end of the tube 28. It should be noted that in this description the
preform and the eventual bottle are assumed to be in conventional
orientation, that is with the mouth at the top and the base at the
bottom. The terms "up" and "down" should therefore be construed in
this sense although in fact the actual orientation of the preform
or the bottle may be different from this.
[0037] The annular or outwardly-extending flange 32 has an upper
surface 34 and a lower surface 36. The upper surface 34 is in part
over the tubular wall portion 28, which thus depends from the inner
edge of the flange. The upper surface 34 carries an upstanding
first detent 40 at or towards its radially inner edge. The detent
40 on its inner periphery is generally perpendicular to the upper
surface 34, and on its outer face slopes down towards the upper
surface 34, as shown in FIG. 3.
[0038] The outer end of the flange 32 terminates in three generally
circumferential elements. The first of these is an
outwardly-extending second detent 42. Above the outer end of the
flange 32 is an upwardly-extending curved-ended sealing portion 44.
This sealing portion 44 will co-operate with a push-on closure for
the bottle to provide a liquid-proof seal adequate to contain the
contents of the bottle when filled with beer or other carbonated
beverage or similar contents. Finally, the periphery of flange 32
carries a downwardly-extending generally-cylindrical flange 46
which is essentially parallel to the upper-most portion of the wall
of the tube 28, as shown in FIG. 3.
[0039] The preform is now transferred to a pressure moulding or
blow moulding machine 50, a section through which is shown in FIG.
4. The mould parts of the machine 50 define the final shape of the
bottle. The exterior part of the body of the bottle is defined by
three mould parts, namely two generally semi-cylindrical side mould
parts 52 separable at an axial plane, and a base punt 54 forming
the base of the bottle. The blow mould also includes neck splits 56
carried by a neck split carrying plate 58.
[0040] When the preform 20 is first inserted in the moulding
machine 50, it is carried by the exterior portion of the rim 30,
and in particular the second detent 42 on the exterior of the rim,
engaging with correspondingly-shaped portions on the lower internal
surface of the neck splits 56.
[0041] The operation of the moulding machine 50 in shaping the
bottle will now be described with reference to FIGS. 5 to 11.
[0042] The operation that takes place in the moulding apparatus 50
is to move the outwardly-extending flange 32, and the first detent
40 with it, downwardly and outwardly, relative to the second detent
42. In effect, the first detent moves pivotally around the second
detent, due to bending of the flange portion particularly at its
outer region. The result of this movement is that the upper surface
34 of the flange 32 now faces inwardly rather than upwardly, and
forms the inward part of the mouth of the bottle. The first detent
40 now projects inwardly into the bottle opening. In this position,
as described below, a closure can be push-fitted onto the rim
portion 30 of the bottle, to engage both the first now inwardly
facing detent 40 and the second outwardly facing detent 42, so that
it is retained on the bottle by these two detents. When the flange
and the first detent have been moved to their final positions, the
tube portion 28 of the bottle is then expanded to fill the inside
of the mould and form the body of the bottle. Although thus
described as two distinct steps, the precise timing of the step of
forming the final shape for the rim of the bottle and the expanding
of the tube can be such that they overlap or are in part
simultaneous, rather than purely sequential as is described.
[0043] In more detail therefore, FIG. 5 shows the preform 20 in the
moulding machine 50, with the blow core 60 of the moulding
apparatus now inserted in the mouth of the mould cavity. The blow
core is shaped to seal against the top of the mould when fully
inserted and has a central throughway through which passes a
stretch rod or pin 62 which can be extended to reach the bottom of
the mould cavity, as described below. The longitudinal passage 64
through which the blow pin 62 passes is wide enough also to provide
for the flow of air under pressure through the blow core past the
blow pin and into the interior of the tubular portion 28 of the
preform 20. An air inlet guide bush 66 is provided within the blow
core 60. The blow core extends into the tubular section 28 below
the periphery of the rim portion 30 of the preform 20.
[0044] FIG. 5 actually shows the blow core 60 before it is fully
inserted. This figure shows the blow core 60 at the position where
a downwardly-extending lip 68 engages with the upper surface of the
transverse flange 32, in the region of the first detent 40. At this
point the preform is at a sufficiently elevated temperature for the
plastics material to be deformable. The blow core is now fully
inserted into the mould to the position shown in FIG. 6. It is in
this operation that the blow core acts as a mandrel and the flange
32 and the first detent 40 are moved downwardly and outwardly,
relative to the second detent 42, forcing the upper surface 34 of
the flange now to face inwardly. The stages of operation are more
clearly seen in FIGS. 7 to 9 which show the rim of the preform and
the bottom of the blow core 60 on a greater scale.
[0045] FIG. 7 corresponds to the position shown in FIG. 5, just
before the blow core is fully inserted. Here the lip 68 is just
starting to make contact with the outer sloping surface of the
detent 40 sufficient to start the bending operation. FIG. 8 shows
an intermediate position between the FIG. 5 and FIG. 6 positions
where the transverse flange 32 and the detent 40 have been
partially moved to their final positions. The pushing effect of the
lip 68 on the blow core 60 engaging with the detent 40 has started
to bend and turn down the flange so as to move the radially inner
portion of the flange carrying the detent 40 relative to the outer
portion of the flange carrying the detent 42. The detent 42 is
being retained in position by its engagement with the neck splits
56.
[0046] The blow core is shown fully inserted in FIG. 9. So far as
the rim is concerned, the lip 68 has now pushed the detent 40 right
around through 90.degree. so that it no longer faces upwardly, but
now faces inwardly into the mouth of the bottle. In this position,
the lower surface 36 of the flange 32 has now been forced round to
the point where it contacts the downwardly-extending cylindrical
flange 46 at the outward end of what was previously the flange 32.
Due to the fact that the plastic is at an elevated temperature, the
underside of the flange 32 melts into and becomes homogeneous with
the cylindrical flange 36, thereby providing strength and solidity
to the structure.
[0047] It will be seen from FIGS. 7 to 9 that the periphery of the
bottom end portion of the blow core 60 is relieved as at 61 to
allow for the shape of the rim portion when the blow core is fully
inserted. In this condition the rim 30 is now clamped between the
neck splits 56 and the blow core 60, with the second detent 42
still engaging the neck splits 56.
[0048] The next stage is for the blow pin to be extended and this
is illustrated in FIG. 10. The blow pin 62 is now fully inserted
into the mould cavity, causing the tubular section 28 to be
stretched longitudinally down to the bottom end of the mould. This
stretching operation is important in providing strength to the
finished bottle when made of PET or PEN.
[0049] Finally, air under pressure is injected through the
passageway 64 in the blow core 60 and around the blow pin 62 into
the interior of the bottle. The effect of this is to expand the
tubular section 28 into the shape of the bottle as defined by the
interior surfaces of the mould parts 52, forming the desired final
shape of the bottle. The mould parts may carry desired shaping to
provide a more complex shaping for the bottle in well known manner.
The expansion of the tubular part will of course thinning of the
bottle wall, as is seen in FIG. 11. Adjacent to the rim portion 30,
the wall now flares away from the rim, this in fact being the
position shown in FIG. 9. The path of the air into the bottle
expanding the bottle is shown by arrows 70 on FIG. 11. The final
bottle shape is now referenced 72 on FIG. 11. The body of the
bottle has now been expanded so that the rim portion 30 is narrower
than the body of the bottle.
[0050] The bottle 72 is now removed from the mould and is shown in
FIG. 12. The base of the bottle as shown in FIG. 12 represents a
modification of the bottle previously described. In this
modification the base has been formed using the process described
in International Patent Application publication number WO97/19802,
to which reference should be made for further description thereof.
Briefly, the base is provided with an undercut re-entrant shape
which provides greater strength to the base portion of the bottle.
This shape is formed by the use of a multipart mould having a
plurality of segments surrounding a tapered core which is moveable
to wedge the segments from a closely packed array to a mutually
spread array. In this manner an undercut shape as shown at 74 can
be provided.
[0051] FIG. 13 represents a detailed sectional view through the rim
portion 30. As is seen, the first detent 40 now constitutes an
inner detent, and the second detent 42, as before, constitutes an
outer detent. A plastics push-on cap can now be provided which
engages with these two detents to secure the cap on the rim of the
bottle. The outer wall forming the body of the bottle now lies
below the outer cylindrical flange 46, while the upper part of the
rim portion 44 forms a seal with the closure as described
below.
[0052] It will be seen from the foregoing that the forming of the
shape of the final bottle in the blow moulding machine is achieved
by a combination of three measures, namely pushing the flange 32
and the top of the wall 28 with the bottom surface of the blow core
60, pulling the wall 28 downwardly by extension of the blow pin 62,
and the application of air pressure through the passage 64 in the
blow core. The manner in which these three measures are best
applied can be determined empirically for any particular situation.
It may be desirable to provide the pushing with the blow core first
followed by stretching with the blow pin and then the application
of pressure. However, it may be preferable for these steps to
partially overlap or to take place simultaneously depending on the
particular application.
[0053] The closure for the bottle will now be described with
reference to FIGS. 14 to 18 of the drawings. The closure, cap or
top 100 illustrated has a planar disc-shaped central portion 102
and a peripheral bottle-engaging portion 104. Across the top of the
disc and the bottling engaging portion 104 are eight
diametrically-extending ribs 106 equally spaced around the disc as
seen from above in FIG. 14.
[0054] As shown in FIG. 15 and more clearly in FIG. 16, the
peripheral bottle engaging portion 104 is generally in the shape of
a trough or inverted U, with opposed inwardly-directed engaging
tangs at the mouth of the U. More particularly, the inner arm of
the U is formed by a cylindrical flange 108 depending from the
outer edge of the disc 102 where it merges into the U shaped
portion or arm 104. The curved portion 110 of the U then merges
into an outer cylindrical portion of arm 112 forming the outer
circumferential part of the bottle-engaging portion 104. The lower
end of the flange 108 carries an outwardly-directed first tang or
finger 114, and the lower end of the outer arm 112 carries a second
inwardly-directed tang or finger 116. Whereas the detents 40 and 42
on the bottle are preferably continuous around the periphery of the
bottle, the tangs 114 and 116 may be and preferably are
discontinuous and each consist of a plurality of discreet tangs
arranged around the circumferential extent of the closure. The
tangs are of slightly lesser extent than the spaces between them.
This facilitates the construction of the mould for moulding the
closure which can then release the closure by a turn-then-push
movement in the manner of a bayonet catch.
[0055] The bottom faces of the first and second tangs 114 and 116
are champhered to allow them to separate as they pass over the rim
portion 30 of the bottle.
[0056] It should be noted that the ribs 106 extend over the U
shaped peripheral bottle engaging portion 104 down to a
circumferential ridge 118 which runs around the bottom of the outer
arm 112. That is to say the remote ends of the rib 106 provides
stiffening for the outer arm 112 of the U section 104. The extent
to which this is required will need to be determined empirically.
FIG. 17 shows an end view of one of the ribs 106 as taken on the
arrow A in FIG. 14.
[0057] When the bottle has been filled with its desired contents,
the cap 100 can be forced on the rim of the bottle to the position
shown in FIG. 18 in sectional view. When the closure is pressed
onto the rim portion 30 of the bottle, the arms 108 and 112 distort
to allow the closure to move onto the rim of the bottle. More
particularly, the two arms of the U open up into a somewhat V shape
so as to pass over the portions forming the rim of the bottle.
First of all, the second tangs 116 engage with the side of the
sealing portion 44 forming the top of the rim of the bottle so as
to pass over the sealing portion 44. The champhering of the bottom
of the tangs 116 assist in this. Then the tangs 116 engage with the
detent 42 while simultaneously the tangs 114 engage with the detent
40. All four elements are angled at their points of contact, so
that further pressure from above causes the inner flange 108 to
move inwardly and the outer wall 112 to move outwardly, allowing
the tang 114 to pass over the detent 40 and the tang 116 to pass
over the detent 42 due to radial flexing. When sufficiently on the
bottle, the tang 114 and the flange 108 move outwardly again to
lock on the underside of the detent 40, while correspondingly the
tang 116 and the outer wall 112 move inwardly to lock and securely
engage on the underside of the detent 42. The flange 108 now
extends into the interior of the bottle. In this position, the
sealing portion 44 co-operates closely with the interior of the
curved portion 110 of the U shaped bottle-engaging portion 104 so
as to provide an effective seal against escape of liquid or the
carbonating gasses within the bottle. The cap can be made of the
same type of plastics material as can be used for the bottle,
including in particular PET.
[0058] Finally, FIG. 19 shows a side view of the completed bottle
with the closure attached. The closure 100 is securely held on the
bottle 72. However the closure 100 can be removed by application of
upward pressure on the ridge 118 forming the outer lower periphery
of the closure. A tool similar to that conventionally used to
remove a metallic crown top from a beer bottle may be used to
remove the closure 100 from the PET bottle 72. The closure 100 will
not however bend in the manner of a metallic crown top but rather
will come off essentially undistorted due to inward flexure of the
flange 108 and corresponding outward flexure of the outer arm 112
of the U shaped element 104, forcing the tang 114 past the detent
40 and likewise forcing the tang 116 past the detent 42.
[0059] Finally, the retaining force holding the closure on the
bottle is such that in the event of excess pressure arising in the
bottle, for example exceeding 90 psi, the closure will be released
from the bottle automatically by the pressure acting on the disc
102.
[0060] The bottle shape obtained is elongate with a longitudinal
axis and is generally circularly symmetrical. However, other or
irregular shapes can be obtained by appropriately shaping the
interior of the mould.
[0061] A preferred embodiment of the invention has been described
by way of example. However, many modifications may be made to the
method, apparatus, bottle and bottle top described, and the
foregoing description should be regarded only as one example of the
implementation of the invention.
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