Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND MO[ILD FOR A CAP ~ITH ~ TAMPER-EVIDENT BA~D
This invention relates to a method and a mould for
injection moulding a cap with a tamper-evident band.
Caps of this type are well known and comprise a cap
proper having a top and a cylindrical skirt, which may
have screw threads for screwing down onto the neck of a
container. At the end of the skirt remote from the top
is provided a band, joined to the skirt by frangible
means. The band has radially inwardly projecting
members. These members are forced down over an outwardly
projecting bead on the container nec~ during initial
mounting of the cap on the neck. The members snap over
the bead and co-operate with the bead to resist removal
of the band. In order to open the container, therefore,
the cap has to be separated from the band at the
frangible means and the separated band, captive on the
container neck, is evidence that the cap has been
tampered with.
Th~e cap, band and frangible means are formed as part
of a single, one-piece injection moulding. The mould has
separable parts, which l;eave the moulded cap and band on
a male core for axial stripping of the cap from the core,
or for unscrewing of the cap from the core. In either
case, this means that it has previously been impossible
for the upper face of each member (that which engages the
bead) to extend in a plane perpendicular to the
longitudinal axis of the cap and of the core, i.e.
perpendicular to the direction of stripping. This is
because such faces would engage the f aces of the core
which formed them and prevent removal of the band from
the core. It has, therefore, been necessary to provide
these upper faces of the members at an oblique angle to
the longitudinal axis to permit stripping from the core.
As a result, the members do not provide good security in
captivating the band on the container neck and it -is
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possible for the whole moulding to be removed from a
container neck and then replaced. Where the oblique
angle has been insufficiently sharp, the top faces of the
members tend to be damaged as the moulding is stripped
from the core~
The present invention permits the top faces of the
members to be both substantial and perpendicular to the
longitudinal axis of the core and cap to provide secure
captivation on the container neck.
In accordance with this invention/ there is provided
a mould for use in moulding a cap attached by frangible
means to a tamper-evident band in which the band has
inwardly projecting members with the faces of the members
nearer to the frangible means e~tending substantially
15 perpendicular to the axis of the band and the cap, the
mould comprising a core on which the cap and band are
moulded, a cavity-forrning portion co-operable with the
core for forming the cap, and radially movable parts
cooperable with the core for forming the band and the
20 frangible means, the radially movable parts having first
surfaces substantially perpendicular to the core axis for
forming said faces of the members, and having second
surfaces which taper outwardly away from the first
surfaces and engage complementary surfaces around the
25 core, whereby, after retraction of the cavity-forming
portion and the radially movable parts, said
complementary surfaces of the core serve to lead the
members off the core as the moulding is removed from the
core.
Preferably, two radially movable parts are provided,
which are separable along a common diame-ter of the core,
each part having a plurality of bosses formed with said
first and second surfaces. The frangible means may
comprise lugs formed between the radially movable parts
35 and the core~
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Also preferably~ the portion of the core which de
fines the members tapers outwardly from said first
surfaces, in the assembled state of the mould, so as to
define members of substantially trianguLar cross-section.
The invention also provides a method of moulding a
cap attached by frangible means to a tamper-evident band
in which the band has inwardly projecting members with
the faces of the members nearer to the frangible means
extending substantially perpendicular to the axis of the
band and the cap, the method comprising moulding the cap
between a core and a cavity-forming portion,
simultaneously moulding the frangible means and the band
between radially movable mould parts and the core, said
faces of the members being formed by the movable parts,
and providing a tapering surface on the core between said
faces and the part of the core forming the cap, whereby,
after retraction of the cavity-forming part and the
radially movable parts, the moulding can be removed from
the core with the members being lead off by the tapering
surface on the core.
Reference is now made to the accompanying drawings,
wherein:-
Figure 1 is a sactional view of a cap with tamper-
evident band made according to the present invention;
Figure 2 is an underneath plan view of the cap and
band; and
Figure 3 is a sectional diagrammatic view of a mould
for producing the cap of Figures l and 2.
The cap and band moulding shown in Figure
30 comprises a cap 10, a band 20 and frangible lugs 30
joining the band to the cap.
The cap has a top ll, formed with inner sealing
projections 12, 13, and a skirt 14, formed with screw
threads 15.
The frangible lugs 30 are relatively thin and join
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the skirt to the band, the lugs being spaced around the
whole periphery of the skirt.
The band is formed with inwardly projecting members
21 which project~ radially inwardly of the inner surface
5 of the adjacent portion of the capO The members are
located between the lugs 30. Each member 21 has a top
face 22 and all the faces 22 lie in a common plane which
is perpendicular to the axis of the cap and the band.
Each member has a triangular cross-section and includes a
10 tapering face 23 which extends from said perpendicular
face 22 and tapers out near the bottom of the band. The
lugs join the band on a circle spaced radially outwardly
of a circle on which the lugs join the cap.
Referring to Figure 3, the mould comprises a core 40
on which the whole moulding is formed. The core includes
a cylindrical surface 41, which co-operates with a
cavity-forming portion 50, to form the skirt 14 of the
cap. The whole cap is formed between this portion 50 and
the core 40.
A pair of sliding parts 60 are provided. These
parts have generally semi-circular cavity forming
portions and are slidable in opposite directions B along
a diameter of the core 40. Only one part is shown in
Figure 3, but both are indicated in Figure 2. These
parts 60 co-operate with the core 40 to form the lugs 30
and the band 20.
A stripper bush 70 is also provided and this
completes the cavity for forming the band 20.
~ fter ~a moulding operation, the cavity-forming
portion SO is retracted in the axial direction of arrow A
and the sliding parts are retracted in the radial
directions of arrows B, leaving the moulding on the core.
The stripper bush 70 is then axially moved to strip the
moulding from the core 40.
Each slidinq part 60 has angularly spaced bosses 61
whose end faces engage with -the core. Between these
b'osses, cavi-ties are defined between the sliding part and
the core to form lugs 30. The bottom face 62 of each
boss is flat and lies perpendicular to the core axis and
the flat faces 22 of the members are formed by these
bottom faces 62 of the slidable parts. The end faces 63
of the bosses taper outwardly from these faces 62. The
core 40 has complementary faces 43 to the faces 63 and
the complementary faces form an outward taper to the
cylindrical surface 41.
After retraction of the mould parts 50 and 60, the
stripper bush 70 pushes the moulding off the core 40.
During stripping, there is no obstacle to the members 21,
despite the fact that their top faces are perpendicular
to the direction of stripping. There is sufficient
resilience in the moulding for the band to be stretched
over the cylindrical surface 41 of the core 40 and the
complementary faces 43 serve to lead the projecting
members 21 out onto the cylindrical surface 41, so that
no damage is caused to the perpendicular top faces of the
members.
The screw threads 15 are diagrammatically shown and
have faces sufficiently angled to the cap axis to permit
the cap to be stripped from the core without damage to
the threads.
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