Note: Descriptions are shown in the official language in which they were submitted.
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METALLIC LID FOR A CAN
Field of the Invention
The present invention refers to a metallic lid of the
type which presents a peripheral side wall provided with
a free upper edge and designed to be frictionally seated
and axially retained in the interior of a seat defined in
an upper opening of the can, the lid being optionally
provided, in its central region, with an inspection
opening to receive an auxiliary lid generally in a
transparent plastic material.
Prior Art
Metallic lids of the type mentioned above are well known.
They are formed in a single piece of metal sheet and
comprise a generally disk-shaped bottom wall, whose
peripheral edge incorporates a side wall projecting
upwardly, so as to be removably press fitted and axially
retained inside a seat defined in an upper opening of a
can. Said seat can be defined by a pending tubular
projection which is superiorly incorporated to a median
opening of the upper wall of a can with a circular or
polygonal cross section.
Metallic lids of the type mentioned above are described
and illustrated in patents US2,074,231, US3,347,408, BR-
8002622-2, BR8002618-4 and also in patents BR9408643-5
and 13R601221-2, the last two pertaining to the same
applicant of the present patent application.
In these prior art constructions, the lid structure
comprises only the bottom wall and a peripheral side
wall, the axial retention of the lid in the seat, defined
in the upper opening of the can, being usually achieved
through engaging means provided in at least one of the
parts of lid side wall and seat in the upper opening, in
order to cooperate with the other of said parts.
In the construction of the type cited above, even when
the bottom wall of the lid presents a drawn or raised
median portion, as taught in the solution disclosed in
patents BR7601221-2 and US3,347,4-8, the lid structure
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requires certain cares to be taken when closing forces
are applied, which forces can irremediably damage said
lid, impeding a tight and secure closure of the can to be
obtained.
The structural deficiency mentioned above is due to the
fact that said lid construction does not present the
usual peripheral strength guaranteed in the metallic lids
provided with a peripheral annular recess, generally
having a cross section with a substantially trapezoidal
and inverted form, to be frictionally seated in the
interior of a recess with a complementary cross section
which defines a seat incorporated to the annular upper
wall of a can body, such as in the construction known for
decades and which is disclosed and illustrated in patent
US795,126, filed in 1904.
In view of increasing the structural strength of the
known lids, which present only the bottom wall and a
peripheral side wall formed to be seated and axially
retained in an upper opening of the can, there was
proposed a constructive solution, which is disclosed and
claimed in the Brazilian patent application PI0405458-0
of the same applicant, according to which the bottom wall
of the lid comprises a peripheral annular portion and a
median portion which are interconnected by an annular rib
portion having the approximate form of an inverted U.
This previous construction provides the lid, which is
formed in a determined metal sheet thickness, with an
increased structural strength, overcoming the deficiency
of these known lids, without requiring the metal sheet
thickness to be increased. The provision of the annular
rib portion in the bottom wall, as proposed in
BR0405458-0, leads to a higher structural strength of the
lid.
However, even incorporating the annular rib portion in
the bottom wall of the lid, the structural strength
necessary for an adequate and secure operational behavior
of the lid still requires the metal sheet to have a
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certain minimum thickness.
Summary of the Invention
As a function of the exposed above in relation to the
prior art, the present invention has as one of its
objects to provide a metallic lid of the type commented
above, which is provided with the annular rib portion in
the bottom wall and which has increased strength to the
extent of allowing said lids to be constructed in metal
sheet with a reduced thickness, without reducing the
structural strength to values lower than those expected
or desired to allow closing and opening the lid by the
usual proceedings, with no risks of producing plastic
deformations which can make said lid become useless.
This and other objects of the present invention are
attained by providing a metallic lid of the type which
has its bottom wall comprising a peripheral annular
portion, adjacent to the side wall of the lid, a median
portion, and an annular rib portion presenting its cross
section with the approximate form of an inverted U, whose
lateral legs are inferiorly and respectively incorporated
to the adjacent edges of the peripheral annular portion
and the median portion of the bottom wall.
According to the invention, the median portion of the
bottom wall comprises an annular panel and a central
panel joined by an axial step portion, an outer
peripheral edge of the annular panel being incorporated
to the adjacent lateral leg of the annular rib portion,
said axial step portion being constituted by a material
that is plastically deformed from the adjacent annular
panel portion and from the central panel portion.
With the construction generically defined above, besides
the fact that the medium portion and the peripheral
annular portion of the bottom wall of the can are joined
to each other by said annular rib portion, the median
portion incorporates the axial step in its radially
median region, which axial step defines one more
structural element incorporated to the bottom wall and
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spaced from the side wall of the lid.
The provision of the auxiliary axial step, additionally
to the provision of the annular rib portion, imparts to
the lid a structural strength that is substantially
greater than that achieved with the prior art
constructions mentioned above, allowing obtaining lids
having adequate structural strength and formed in a metal
sheet with a smaller thickness, that is, with less
material consumption.
Furthermore, the construction of the lid object of the
present invention can be made so that the central panel
of the median portion of the bottom wall presents an
inspection opening defining a seat for seating and
axially retaining an auxiliary lid in a transparent
plastic material.
Brief Description of the Drawings
The invention will be described below, with reference to
the enclosed drawings, given by way of example of
possible constructions for the present lid and in which:
Figure 1 represents a partial diametrical sectional view
of the upper region of a can, in whose discharge end
opening is fitted a lid constructed according to one of
the known prior art solutions;
Figure 2 represents a top plan view of a lid of the type
illustrated in figure 1, but incorporating the axial step
according to a first embodiment of the invention;
Figure 3 represents a partial diametrical sectional view
of the lid, when mounted in the discharge end opening of
a can, said view taken according to line III-III in
figure 2;
Figure 4 represents a top plan view of a lid of the type
illustrated in figure 2, but incorporating radial
extensions of the central panel, according to a second
embodiment of the invention;
Figures 5 and 6 represent partial diametrical sectional
views of the lid when mounted in the discharge end
opening of a can, said views taken according to lines V-V
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and VI-VI, respectively, in figure 4;
Figure 7 represents a top plan view of a third embodiment
of the lid of the present invention; and
Figure 8 represents a partial diametrical sectional view
of the lid when mounted in the discharge end opening of a
can, said view taken according to line VIII-VIII in
figure 7.
Detailed Description of the Invention
As illustrated in the enclosed drawings, the lid of the
present invention is applied to a can 10, which is
graphically represented only by the upper portion of its
side wall 11, to whose upper edge is affixed, usually by
means of a double-seaming 12, an outer peripheral edge of
an annular upper wall 13 in whose median region is
provided an opening 14 to whose edge is incorporated a
pending tubular projection 15 which defines a seat "S"
for seating the lid of the can.
In the prior art construction exemplified in figure 1 of
the drawings and which is object of patent DR9408643-5 of
the applicant of the present patent application, the
pending tubular projection 15 is provided with a lower
end portion which is bent inwardly of the opening 14,
upwardly and against the pending tubular projection 15,
so as to form a continuous tubular rib 16, which has a
generally circular shape, as described in said prior art
patent.
However, it should be understood that the construction of
the pending tubular projection 15 of the annular upper
wall 13 of the can 10 may have different constructive
arrangements, as illustrated and discussed in the prior
art documents mentioned above, without said constructive
modifications altering the constructive and functional
objectives of the present invention.
As already previously mentioned, the lid 20 of the
present invention is formed in a single piece of metal
sheet, comprising a bottom wall 21 usually in the form of
a flat disk and which superiorly and peripherally
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incorporates a side wall 22 provided with a free upper
edge 22a and designed to be frictionally seated and
axially retained inside the seat "S" defined by the
pending tubular projection 15 of the opening 14 provided
in the annular upper wall 13.
In the exemplary construction illustrated in the
drawings, the lid 20 has its side wall 22 provided with a
continuous peripheral recess 22b, inside which is
sealingly fitted and axially retained the continuous
tubular rib 16 of the pending tubular projection 15.
In the illustrated construction, both the continuous
tubular rib 16 of the pending tubular projection 15 and
the continuous peripheral recess 22b of the side wall 22
of the lid 20 present a contour which is at least
partially circular and complementary, so that the mutual
seating of said parts promotes not only the axial
retention of the lid 20 in the opening 14 of the can 10,
but also a sealing effect in this frictional seating
region. It should be understood, however, that the
continuous tubular rib 16 and the continuous peripheral
recess 22b might present configurations other than that
tubular circular illustrated in the drawings, as can be
observed in the prior art documents cited in the
beginning of the present description.
Still according to the embodiment illustrated in the
drawings, the lid 20 has its free upper edge 22a bent
outwardly, downwardly and against the side wall 22, so as
to define a tubular upper rib 22c to be seated on the
annular upper wall 13 of the can 10, in the region that
surrounds the opening 14. Accordingly, it should be
understood that the free upper edge 22a of the side wall
22 of the lid 20 can present different constructive
forms, as illustrated in the prior art documents
previously cited, without said modifications of form and
arrangement of the upper region of the side wall 22 of
the lid 20 altering the functional characteristics of the
invention proposed herein.
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According to the invention, the bottom wall 21 of the lid
20 comprises a peripheral annular portion 23 adjacent to
the side wall 22, a median portion 24 and an annular rib
portion 25 presenting a cross section with the
approximate form of an inverted U, whose lateral legs are
inferiorly and respectively incorporated to adjacent
edges of the peripheral annular portion 23 and median
portion 24 of the bottom wall 21.
The annular rib portion 25 is stamped jointly with the
remainder of the lid 20, in order to project preferably
upwardly from the peripheral annular portion 23 and from
the median portion 24 of the bottom wall 21, the annular
rib portion 25 remaining spaced from said side wall 22 by
an adequate distance, so as to provide to the marginal
region of the lid 20 the necessary structural strength to
resist the compression forces to be applied over the lid
20, upon fitting the latter in the opening 14 of the can
10.
Still according to the preferred embodiment, the median
portion 24 of the bottom wall 21 is disposed in a higher
plane in relation to a plane which contains the
peripheral annular portion 23 of said bottom wall 21.
This constructive arrangement allows the median portion
24 of the bottom wall 21 to operate jointly with the
annular rib portion 25 to define seating means to place
one lid over the other, upon stacking said lids in a lid
feeding device in an automatic can closing machine, or to
allow the lids 20 to be automatically fitted in
respective annular upper walls 13, before they are
double-seamed to the side wall 11 of the cans 10.
The annular rib portion 25 is further constructed and
dimensioned in such a way as to be disposed inferiorly to
a plane Ps containing the free upper edge 22a of the side
wall 22 of the lid 20, this relative dimensioning of the
lid parts being made as a function of the stacking
characteristics cited above and discussed in BR0405458-0.
According to the present invention, the median portion 24
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of the bottom wall 21 comprises a generally flat annular
panel 24a having an outer peripheral edge which is
incorporated to the adjacent lateral leg of the annular
rib portion 25 and an inner peripheral edge incorporated,
by an axial step portion 24c, to an outer peripheral edge
of a central panel 24b, which is also generally flat and
disposed in a plane slightly superior to that of the
annular panel 24a.
In order that the lid 20 presenting the axial step
portion 24c can be formed from a metal sheet blank with
the same dimensions as those necessary for producing the
lid defined in figure 1 and provided with the annular rib
portion 25, the axial step portion 24c is constituted by
a material that is plastically deformed from the adjacent
annular panel portion 24a and from the central panel
portion 24b.
The provision of the axial step portion 24c increases the
structural strength of the lid 20, particularly of its
bottom wall 21, in a sufficient degree to allow the usual
thickness of the metal sheet of the lid to be reduced,
without the structural strength of the lid reaching
values which are unacceptable or harmful to the correct
and secure closing and opening operations of the can by
means of the lid.
In the embodiment illustrated in figures 2 and 3, the
central panel 24b is completely closed and deprived of
any opening, having a radius R which corresponds to about
the double of the radial width RL of the annular panel
24a.
The height of the axial step portion 24c should be only
sufficient to produce the desired effect of increasing
the structural strength of the lid 20, generally with a
value approximately equal to the thickness of the metal
sheet used to form the lid 20, so that the material used
to form the lid results exclusively from the material
that is plastically deformed from the adjacent annular
panel portion 24a and from the central panel portion 24b
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during the stamping operation of the lid.
In the second embodiment illustrated in figures 4, 5 and
6, the central panel portion 24b of the median portion 24
of the lid 20 incorporates a plurality of radial
extensions 24d, coplanar to said central panel portion
24b and which extend until the adjacent lateral leg of
the annular rib portion 25, to which they are
incorporated. In the illustrated embodiment, the radial
extensions 24d are in the number of four, but they can
vary above or below this number. However, it is desirable
that said radial extensions 24d be equally and angularly
spaced from each other. It is further possible to stamp
the lid 20, so as to allow the radial extensions 24d of
the central panel 24b to be disposed in a plane slightly
axially offset from the plane of said central panel 24b.
In the embodiment illustrated in figures 7 and 8, the
central panel 24b is provided with an inspection opening
26 radially spaced from the axial step portion 24c,
defining a seat for seating and axially retaining a
peripheral side wall 31 of an auxiliary lid 30 in a
transparent plastic material, said inspection opening 26
comprising a pending skirt 27 formed to incorporate an
inner circumferential rib 28 to be fitted in a
corresponding circumferential recess 33 provided in the
peripheral side wall 31 of the auxiliary lid 30. The
construction of the inspection opening 26 and of the
auxiliary lid 30 can follow the same proceedings applied
to the lid 20, maintaining the dimensions of the involved
parts proportionally adequate to the smallest diameter of
the auxiliary lid 30. It should be understood that the
radial extensions 24d of the central panel 24b, in this
case being also annular, may be also provided in the
embodiment illustrated in figures 7 and 8.
In the embodiment illustrated in the drawings, the
peripheral annular portion 23 and the median portion 24
of the bottom wall 21 of the lid 20 are flat.
While only some constructive forms for the lid, jointly
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with a seat construction, have been illustrated herein,
it should be understood that alterations can be made in
the form of the component parts, without departing from
the constructive concept defined in the claims that
accompany the present specification.
