Note: Descriptions are shown in the official language in which they were submitted.
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This Lnvention is concer~led with improve~ents
in or relating to drums.
A well known type of drum comprises a cylindrical
metal body portion and opposed end portions connected to
the body portion by seams~
One problem which arises ~rith this type of drum,
particularly in t~e larger sizes, is that the seams present
an area of weakness liable to ~ail, for example on impact
when tlle drum is dropped from a height.
It is an object of the present in~ention to
provide a drum in w~ich this problem is minimised.
Surprisin~ly, we have found that resistance
to failure on impact can be enhanced by reducing the
cross-section of the body portion ad~acent the seams.
According to one aspect of the present invention
~here is ~rovided a drum having a capacity of at least
~i~e litres and comprising a circular cylindrical metal
body portion of predominantly uniform cross-section,
first and second end portions, a first interlocked seam
connecting the first end portion to ~he body portion at
one end of the body portion, a second interlocked seam
connecting the second end portion to the body portion
at a second end of t~le body portion, a first portion of
the body portion adjacent the first seam and a second
portion of the body portion adjacent the second seam,
wherein each o~ the first and second portions of the body
portions is necked-in so that the cross-section of the
drum adjacent the seams is reduced, the first and second
necked-in portions of the body portion each comprising
3 a frusto-conical portion extending inwardly to the
longitudinal axis of the drum and adjoining and connec~ed
by a first fold to the body portion of p~edominantly
uniform cros~-section, the first ~ld second necked-in
portions oE the body portion each furtller comprising a
substantially circular cylindrical shaped portion adjoining
the seam and co~ected by a second fold to the correspo~ling
frusto-conical portion, the necked-in portions being
adapted to crush at the folds under impact to minimise
damage to the interlocked seams.
According to another aspect of the present
invention there is provided a method of manufacturing a
drum having a capacity of at least five litres and
comprising a circular cylindrical metal body portion of
predominantly uniform cross-section and first and
second end portions, comprising the steps of carrying out
a reduction operation on a respective portion o~ the bod~
portion ad~acent each end thereof, w~ich reduction
operations result in a respective frusto-conical portion
extending inJa~dly to the longitudinal aY.is of the drum and
adjoining and connected by a first fold to the body portion
of predominantly uniform cross-section, and a substantially
circular cylindrical shaped portion axially outward of the
frusto-conical portion and connected thereto by a second
fold, and seaming each of the end portions to a
respective end of the body portion ~Jhereby to produce
an interlocXed seam therebe~Jeen, the cross-section of
the drum adjacent the seams being reduced in comparison
with the predominantly uniform cross-section of the
majority of the metal body portion.
The invention is particularly, but not exclusively,
applicablP to d-~wms having a capacity of at least 200 litres.
For example, the in~ention is applicable to
3 drums having capacities from 5 to 250 litres. Particular
exa~ples ~ithin this range include the ~ollo~ing:-
5 to lO litreslO to 25 litres
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25 to 50 litres
50 to 100 litres
100 to 150 litres
150 to 250 litres.
The wall thickness o~ the body portion generally
increases with capacity, other ~actors being equal, and
for example in the range ~rom 50 litres tc 250 litres
the wall thickness may vary ~rom 0.4 to 1.6 mm.
Examples o~ metals for the body portion and end
portions include mild steel, stainless steel and aluminium.
The above and other aspects o~ the invention
will become more clear ~rom the ~oll~wing description,
to be read with re~erence to the accompanying dra~ngs~
. This description, which is illustrative o~ product and
method aspects of the irlvention, is given by way o~ -
example only, ~n~ not by way o~ limitation o~ the
invention~
In the accompanying drawings:-
Figure 1 shows a side view o~ a ~irst drum
embodying the in~ention;
Figure 2 sho~s an enlarged sectional sid~
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~iew of a top ~eam of the drum shown in Figure 1;
Figure 3 show3 a plan view of the drum shown
in ~igure 1;
Figure 4 illustrates an intermediate stage
in the manufacture of the drum of ~igure 1;
~igure 5 is a view corresponding to Figure 2,
but relating to a ~econd drum embodying the invention; and
Figures 6 to 14 illustrate variou~ modifications.
The first drum embodying the i~ention (~igures
1, 2 and 3), compri3esa circular cylindrical metal body
portlon 10 of uniform cross-~ection, except for two
outstanding ribs 12 located at a central region of the
body portion. ~he drum also comprises a dished
metal upper end portion 14, and an oppo~ed metal
lower end portion 16, which are connected
to the body portion at the opposite ends thereof by
sea~s 18, 20 respectively.
The body portion 10 i8 necked-in at 22, 24
ad~aoent the ~eam~ 18, 20, ~o that the cro~-sections
at the seams are reduced, and are smaller than and lie
wholly within the predominantly uniform cro~-section
of the body portion 10. (See ~igure 2). The necking-in
results in a frusto-conical configuration at 26, 28
adJacent each end of the body portion 10.
The anglec~ to the vertical of each frusto-conioal
configuration 26, 28 i~ between 5 and 60, preferably
between 10 and 50, e.g. 30; and the regions 27, 29
of the body portion 10 which lead from the fru~to-conical
configurations to the seams 18, 20, are preferably
parallel to the main axis of the body portion 19.
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The seam 18 i9 an interlocked seam of known
type having five layers, three from the end portion 14,
and two from the body portion 10. The ~eam 20 corresponds
in construction and arrangement to the seam 18.
lhe upper end portion 14 i~ circular (Figure 3),
and comprises octagonal pressed-up portion~ 30, 32, in
which are provided threaded pour and vent openings 34, 36
respecti~ely. The opening~ 34, 36 are closable by threaded
plug~ (not shown).
The lower end portion 16 corresponds in
construction and arrangement to the upper end portion
14, except that there are no pour and vent openings
or corresponding octagonal portions.
Both end portions 14 and 16 are di~hed
inwardly of the respective seams 18, 20, and comprise
outwardly domed central portion~, as ~hown at 15 in
Figure 2.
In the manufacture of the drum, the necking-in
i~ obtained by carrying out a reduction operation u~ing
a roller necklng tool or a segmental shrinking tool on
the body portion 10, ad~acent each seam 18, 20, and each
reduction operation i8 carried out simultaneou3ly with
the pro~ision Or an outwardly extending flange (40 in
Figure 4) which i9 subsequently folded over with metal
of the end portion to form the seam. It will be noted
that an actual reduction operation i3 involved at 22, 24,
and the necking-in is not provided by outwardly expanding
. regions of the body portio~ 10, complementary to the
necked-in regions.
The extent of the necking-in is for example,
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such a~ to reduce the internal diameter of the body
portion at the seam by up to 10%, 12~ or 15~0 for ~maller
drum~, and up to 5% or 7% for larger drum~ Even bigger
reductions are conceivable, e.g. up to 18~ or 20%. These
percentages are calculated a~ D-d X 100, where (Figure 2)
d is the internal diameter at the seam, and D the internal
diameter of the predominantly uniform cross-~ection of
the body portion 10.
We believe that the drum embodying the invention
has enhanced resistance to failure on impact, as evinced
by standard drop tests, because the impact force is
lessened by crushing pro~ided by collap~e at the ~etal
folds 31 defining the upper and lower boundaries of the
frusto-conical portion 26 or 28. ~ateral distortion of
the seam 18 or 20 is reduced as the seam telescopeæ within
the protection of the cylindrical body portion 10, leaving
the inner juxtaposition of the seam and body portion
relatively undistorted,
Also, the necking-in facilitates safe handling
of the drum by reducing the risk of finger entrapment
by the seams.
The second drum embodying the invention
(Figure 5) resemble~ the first drum in many respect~ of
constructlon and arrangement, and l~ described ln ~o far
as it differs therefrom.
In the second drum, the seam 18 (and the
¢orrespondine bottom seam - not shown) is an interlocked
seam of known type having ~e~en layers, four from the
end portion 14, and three from the body portion 10. It
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will be noted in this case that although the cross-section
at the seam 18 is reduced, it is not,because of the width of the
seam smaller than that of the predominantly uniform
cross-section of the body portion 10.
The modification3 shown in Figures 6 to 10
are applicable equally with the seam formation of
Figure 2 or that of Figure 5; and further mo~ifications
may comprise different forms of seams, e.g. welded seams.
It is belie~ed that the modification~ of
Figure6 6 to 10 may provide additional strengthening
¢haracteri~tics,for exsmple to resist axial compression
in the thinner metal gauge3.
In each of the modificationa, the seaming
and necking-in configurations ars the same at both
ends of the drum.
In the modification of Figure 6, the co~figuration
26 compri3es three evenly stepped fru~to-conical portions
26a~ 26b and 26c~
In the modification of Figure 7, a plurality of
evenly spaced axial notches 42 are indented in the body
portion 10, and each notch extends across the boundary
between the frusto-conical configuration 26 and an adjacent
region of the body portion 10, which region is axially
inward of said configuration. The width of each notch is
approximately equal to the distance between adjacent notches.
In the modification of Figure 8, a plurality
of evenly spaced pressed-out helical ribs 44 are provided
on the frusto-conical configuration 26, the ribs 44 being
inclined to the axis of the drum.
In the modification of Figure 9, a continuous
pressed-out sinuous rib 46 is provided on the frusto-conical
configuration 26.
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In the modification of Figure 10, an annular
bead 48 is pressed upwardly in the domed portion 15
ad~acent its periphery and radially inwardly of the seam.
In the modification of Figure 11, the drum
is open-topped and the body portion 10 comprises a
curled over bead 118 providing a rim of the open top.
A metal removable closure 120 is sealed against the
bead 118 via a gasket 122, and the closure 120 is
secured in position by a releasable ring 124 which ls
of generally U-shaped cross-section with one limb
engaglng the closure 120 and the other limb engaglng
the bead 118. The rlng 124 comprises for example, a
lever assembly (not shown), operation of whlch releases
the ring 124.
In other respects, this modification resembles
the drum described with reference to Flgures 1, 2 and
3 or Flgure 5 and may comprise features of any of the
other modifications described herein. The necXing-in
ad~acent the curl 118 will be noted. It will be
reallsed that this necking-in facilitates rolling of
the drum along the ground on the ribs (12 - Figure 1)
wlthout fouling the ring 124 agalnst the ground, whlch
would be liable to cause damage and possibly premature
opening of the drum.
Again, the modifications shown in Flgures
12, 13 and 14 are applicable equally wlth the seam
formation of Figure 2 or that o~ Figure 5; and further
modifications may comprise different forms of seams,
e.g. welded æeams.
In each of the modifications of Figures 12,
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13 and 14, the necking-in results in a configuration
126 ad~acent the upper end of the body portion 10
which config~atlcn is sinuous in a direction axial
of the body portion; and a corresponding sinuous
conflguration (not shown) ad~acent the lower end of
the body portion 10. In Figure 12 the sinuous
configuration is relatively abrupt; in Figure 13 it
i8 much less abrupt; resembling a bottle neck to
give high compression resistance; and the sinuous
configuration of Figure 14 i8 intermediate those
of Figures 12 and 13.
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