Note: Descriptions are shown in the official language in which they were submitted.
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This invention concerns plastics material lids for
containers.
Today, plastics material containers which are thermo- ~-
form~d from sheet material are in extensive use, for con-
taining foodstuffs such as cream, yoghurt, mousse and ice
cream. These containers always have lids, but generally
speaking are lidded either with metallic foil or waxed
cardboard. The utilization of different materials for
lid/lidding and container i8 an inconvenience because
this u#ually involves two suppliers This invention i8
concorned with providing plastics material lids whereby
at least the said inconvenience, where the lids are u~ed
with plastics material containers, can be overcome.
According to the present invention, there i~ provided
n lid for a cpntainer, comprising a body which i8 moulded in
that it is thermoformed from plastics sheet material and
which has a top panel having a rim adapting the body to be
s~cured to a container top, said top panel having a region
thereof defined by a line of weakening and the lid including
means in addition to the body and not moulded integrally
therewith for facilitating the application of force to a
part of said region and in a direction generally at right
angles to the panel, to enable tearing along said line of
weakening to permit access to a container closed by the lid,
characterised in that the body is of circular form, and
~aid region is of circular form and i8 surrounded by a rim
portion for remaining connected to the container when said
rogion is removed or flexed back, and said region has a
raised horse-shoe shaped portion whose outer edge lieq close -~
to said line of weakening and said means for facilitating
fracture comprises a pull tab having a portion which can be
gripped by the fingers lying between the limbs of the said
hors~-~hoe portion and another portion connected to the said
region.
By the expression ~thermoformed from plastics sheet"
as usod herein and in the appended claim is meant forming
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the sheet when heated by means of vacuum, fluid under
pressure (with or without plug assist) or mechanical forming
or a combination of these methods.
An embodiment of the present invention will now be
described, by way of example, with reference to the drawings
accompanying the provisional specification, wherein:-
Figs. 1 and 2 respectively show in perspective andsectional side elevation a lid according to the embodiment
of the invention~ and
Figs. 3, 4 and S, show in sectional elevation, three
~teps in carrying out a method of applying a lid to a
container.
Referring to the drawings, Figs. 1 and 2 show a circular
lid for an appropriately shaped circular sectioned container
(not shown). The lid basically comprises a body having a
top panel and a downwardly directed peripheral flange. The
body is thermoformed from plastics material sheet.
The body panel is indicated by numeral 22 and the body
has a flange 24 and has a line of weakening 26 which is
circular and concentric with the circular form of the panel
; 22. Within the region defined by the line 26 there is
moulded a raised horse shoe shaped portion 28 the centre of
which lies centrally of the panel 22, and the outer ledge
lies close to line 26. A snap 30 is adhered to the top
panel 22 within the region defined by line 26 such that an
edge thereof lies between the arms of the horse shoe shaped
portion 28 and such that the thumb can be slipped under
this edge in order to grasp the tab 30 which has a pointed
end 32 lying adjacent the line 26, and pivot it so that it
acts as a lever in order to form an initial fracture in the
line 26 adjacent the point 32 whereby the whole of the section
within line 26 can subsequently be removed. The tab 30
may be applied to the panel 22 by any suitable means such
a~ adhesive or ultrasonic welding or a combination of such
means. If reference is made to Fig. 2, it will be seen
that the line 26 is in fact defined by a cutting through the
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thicknes~ of the sheet material from which the lid is formed.
After the formation of the bodies of the lids, the
line of weakening subsequently is put into the top panels
and then the tabs 30 are applied and then the lids are
5 removed from the sheet stock in which they are formed.
It will be noticed that the body is fractured along
the line of weakening by the application of force, through
the means 30 which is in a direction substantially at
right angles to panel 22.
It is not necessary that the lid 3 be provided with the
flange 24. This flange could be omitted and the lid could
be applied where appropriate, and where the materials permit,
to the container by the use of adhesive or by the use of
wolding or by a combination of both techniques.
The lid as described can be crimped or clinched onto a
top peripheral flange of an appropriate containers. An
example of such application is illustrated in Figs. 3, 4 and
5. In these Figs., a container is indicated by numeral 48
whilst the lid is indicated by numeral 50. ~ach of these
drawings is a sectional drawing showing only part of the
container and lid but it is sufficient to show the method
of operation. It will be seen that the lid 50 is placed
over the container 48, which has a top peripheral and out~
w~rdly extending flange 52, such that the downwardly ext-
ending flange 54 of the lid surrounds flange 52. The flanges
54 and 52 lie within a forming ring 56 having a circumfer-
~ ential shoulder 58 of which the bottom is curved as shown.
- Overhead there is provided a pressing die 60 having a
peripheral face 62 which is adapted to press the outer
surface of the lid 50 onto the flange 52. A heater 64 is
attached to the ring 56 so as to cause the transfer to heat
; through the ring to the flange 54 which is deformed during
the subsequent operation.
; With the flange heated to appropriate temperature the ~ ~
die 60 is lowered as indic ted by arrow 66 in Fig. 3 thereby
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pressing the flange 54 axially towards the rounded bottom
of shoulder 58. This causes the flange, now reasonably
soft, to turn inwards as shown in Fig. 4 and eventually,
when downward movement of die 60 is complete, to be
clinched under and round the flange 52 thereby securing
the lid 50 firmly to the container.
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