Note: Descriptions are shown in the official language in which they were submitted.
28~iS
INDUSTRIAL DRUMS CONFIGURED FOR
MECHANIZED AND MANUAL HANDLING
The present invention relates generally to industrial
drums and pertains, more specifically, -to industrial drums con-
structed of synthetic resin materials for use in the trans-
portation and storage of goods which are usually in liquid form.
Industrial drums have long been a staple product used in
the transportation and storage of goods in liquid and liquid-
like forms. The now ubiquitous fifty-five gallon drum is an
example of a versatile container which has been manufactured
for many years in numerous forms. The conventional form for
such drums is a cylindrical configuration with integral annular
chimes. Such a configuration has been reduced to more-or-less
standard shapes and dimensions to enable mechanized drum-handling
equipment and storage facilities to be developed on a more uniform
basis.
More recently, industrial drums have been constructed of
synthetic resin materials in attempts to gain superior corrosion
resistance and ease of manufacture, as well as other beneficial
characteristics provided by the newer materials. However, the
more commercially acceptable plastic drums have been constructed
in configurations which represent a considerable departure from
the widely accepted cylindrical drum with its annular~ chimes.
Attempts at duplicating the accepted aspects of the conventional
cylindrical drum in a synthetic resin drum have met with problems
relating to attaining the appropriate strength in a container
manufactured by economical molding techniques. In an earlier
Canadian Patent No. 1,083,055~ issued August 5, 1980, drum
configurations and manufacturing techniques and materials
are described which enable the construction of industrial drums
offering the advantages of present drums of conventional size
and configuration, but which can be fabricated economically
of a synthetic resin material which offers high strength and
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increased durability, as well as further advantages such as
corrosion resistance and ease of maintenance.
An object of the present invention is to provide an
improved industrial drum configuration constructed of synthetic
resin material and which facilitates handling of the drum both
manually and by the use of conventional mechanized material
handling devices, while providing a reinforcing structure for
strengthening the drum, all without departing drastically from
current conventional drum configurations.
Another object of the invention is to provide an
industrial drum of synthetic resin material in which different
surface areas of the drum are provided with specific surface
finishes for enabling ease of labelling, handling and storage
of the drum.
Still another object of the invention is to provide in-
dustrial drums of synthetic resin material with bottom end members
having a specific load-reinforcing configuration.
A further object of the invention is to provide in-
dustrial drums of the type described and which include a bung
opening for a conventional threaded closure, the bung opening
being provided by a threaded insert o~ a material haviny greater
toughness and a higher melting point than the material of the
drum so that the threaded insert can be molded in place during
fabrication of the drum, the threaded insert having a special
external thread for securing the insert in place in the drum
wall while enabling selective removal and replacement of the
insert.
A still further object of the invention is to provide an
industrial drum configuration which can be fabricated by rotation-
al molding and provides a rugged container capable of a long
service life under a wide variety of conditions.
The above objects, as well as still further objects and
advantages, are a-ttained by the present invention which may be
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l~escribed ~riefly as an industrial drum constructed of molded
synthetic resln material and capable of being transported in an
upright position when filled, the drum comprising a generally
tubular body member extendiny longitudinally between opposi-te top
and bottom ends when the drum is in the upright position, first
and second end members for closiny the opposite ends, one of
which end members is a bottom end member molded unitary with the
tubular body member at the bottom end thereof, an annular base
located adjacent the intersection of the bottom end member and
the tubular body member, the annular base having a first basal
support located ln a basal plane and upon which the drum is
supported when in the upright position, and a further support
portion in the bottom end member, the further support portion
being spaced laterally inwardly from the annular base and having
a further basal support for providing an auxiliary support for
the drum when the drum is in the upright position and is filled.
Additionally, the further basal support can be spaced
longitudinally upwardly from the first basal support when the
drum is empty, and the bottom end member is flexible so as
to enable do~ward displacement of the further basal support
to the basal plane when the drum is filled.
In a further embodiment, the invention con-templates an
industrial drum constructed of molded synthetic resin material
which comprises a generally tubular body member extending longi-
tudinally between opposite ends, with first and second end members
molded unitary with the tubular body member for closing the
opposite ends. The tubular body member includes a generally
cylindrical, longitudinally extending portion terminating.at
longitudinally opposite boundaries adjacent the opposite ends
and having a first outside diameter, with the longitudinally
extending portion including a generally cylindrical ou-ter surface
having a smooth matte finish for facilitating the adhesive
application of a label thereto.
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The invention will be more fully understood, while
still further objects and advantages will become apparent,
by reference to the following detailed description of an ~.
embodiment of the invention illustrated in the accompanying
drawing, in which: :
FIG. 1 is an elevational view, partially cut away,
of an industrial drum constructed in accordance with the
invention;
FIG. 2 is a top plan view of the drum;
FIG. 3 is a bottom plan view of the drum;
FIG. 4 is an enlarged fragmentary cross-sectional
view of the bottom end portion of the drum when the drum is
empty;
FIG. 5 is an enlarged fragmentary cross-sectional
view of the bo~tom end portion of the drum when the drum is
full;
FIG. 6 is an enlarged fragmentary cross sectional
view of another portion of the drum;
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The invention will be more fully understood, while
still further objects and advantages will become apparent, by
reference to the following detailed description of an embodiment
of the invention illustrated in the accompanying drawing, in
which:
FIG. 1 is an elevational viewt partially cut away, of
an industrial drum constructed in accordance with the invention;
FIG. 2 is a top plan view of the drum,
FIG. 3 is a bottom plan view of the drumi
FIG. 4 is an enlarged fragmentary cross-sectional view
of the bottom end portion of the drum when the drum is emptyi
FIG. 5 is an enlarged fragmentary cross-sectional view
o the bottom end portion of the drum when the drum is full,
FIG. 6 is an enlarged fragmentary cross-sectional view
of another portion of the drum;
FIG. 7 is an enlarged fragmentary cross-sectional view
of still another portion of the drum;
FIG. 8 is an enlarged, exploded, cross-sectional view
of a further portion of the drum illustrating the component
parts of the closure assembly; and
FIG. 9 is an enlarged, cross-sectional view similar to
FIG. 6, but with the component parts assembled.
Referring now to the drawing, and especially to FIGS.
1, 2 and 3 thereof, an industria]. drum constructed in accordance
with the invention is illustrated at 10. Drum 10 has a generally
tubular body member 12 which includes a unitary cylindrical side
wall 14 extending longitudinally between a top end 16 and a
bottom end 18. A first end member 20 includes a generally cir-
cuIar top end wall 22 which is unitary with side wall 14. A
second end member 24 includes a generally circular bottom end
wall 26 which also is unitary with side wall 14. Drum 10 is
shown empty and resting in a vertical position on a horizontal
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support surface 28.
Side wall 14 has a longitudinally centrally located first
portion 30 which is in the ~form of a generally straight cylinder
extending longitudinally between upper~boundary 32 and lower
boundary 34, each boundary'32 and 34 being spaced from a
corresponding end 16 and 18. First portion 30 has an outside
diameter which is essentially~constant along the length between
boundaries 32 and 34. A pair of annular ribs 36 is placed
adjacent each boundary'32 and'34 and spaced from a corresponding
end 16 and 18.
The overall outside diameter of ribs 36 is greater than
the outside diameter of first portion 30'and is greater than the
outside diameter of any further portion of drum 10. Thus, upon
placement of the drum upon support surface 28 in a horizontal
position, that is, with the central longitudinal axis C of the
drum parallel to the support surface 28, as shown in phantom in
FIG. 1, ribs 36 serve as contacts which rest upon the support
surface 28. ~he space 40 between each of the ribs 36 of a pair
of ribs 36 is made great enough to accommodate the load-engaging
tines of a conventional material handling device, such as the
tines 42, illustrated in phantom in FIG. 1, of a conventional
fork lift truck (not shown). In addition, the space 40 between
the ribs 36 of each pair of ribs 36 is great enough to accommodate
the jaws (not shown) of a conventional drum-handling device known
as a "grabber". Further, the provision of a plurality of ribs
36 establishes a reinforcing structure for strengthening the
side wall 14 of the drum 10.
Top end wall 22 is unitary with side wall 14, and an
integral chime 46 is provided at the intersection of top end wall
22 and side wall 14. Chime 46 has a configuration which enables
the drum 10 to be handled with drum~handling equipment of the
type such as that described in United States patent no. 2,814,403,
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all as more fully described in the aforesaid Canadian Patent
No. 1,083,055, issued ~ugust 5, 1980. Thus, mechanized handling
of drum lO is readily accomplished with a variety of different
types of conventional drum handling devices. Chime 46 is pro-
vided with two drain troughs 48. The location of the drain
troughs 48, together with the slightly domed configuration of
the top end wall 22, facilitates the draining of any liquid
which might otherwise tend to collect upon the top end wall 22.
As best seen in FIGS. l and 3, the second end member 24
includes an annular base portion 50 located at the intersection
of the bottom end wall 26 and the side wall 14. The annuIar base
portion 50 is circular and includes a primary basal support 52
upon which drum lO is supported when in the upright vertical
position shown. Spaced laterally inwardly from the annular base
portion 50 is a further support portion in the form of an
annular support ring 54, molded integral with the bottom end
wall 26, and including further basal support 56.
Turning to FIGS. 4 and 5, as well as to FIGS. 1 and 3,
when the drum lO is empty, further basal support 56 is spaced
lon~itudinally upwardly from primary basal support 52, as seen
in FIG. 4; however, upon filling the drum lO, as seen in FIG. 5,
the flexible nature of bottom end wall 26 enables downward
displacement of annular support ring 54 until further basal
support 56 rests upon horizontal support 28, thereby providing
an auxiliary support for drum lO when the drum is filled. The
auxiliary support is effective during the transportation of a
loaded drum in that the bottom end wall 26 is reinforced against
excessive up and down movement under load. Such excessive up
and down movement under load has been responsible, in the past,
for failure of the bottom end wall. By reinforcing against
that constant up and down movement, the annuIar support ring 54
and the further basal support 56 thereof extends the useful
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service life of the drum 10
Drum 10 preferably is fabricated by rotational molding
and is constructed of a synthetic resin material suitable for
rotational molding. One such material is polyethylene. The
rotational molding process lends itself well to molding the
tubuIar body member 12, the top end member 20 and the bottom
end member 24 in a unitary structure.
The rotational molding process also provides a slmplified
method of establishing specific surface finishes upon different
surface areas of the drum 10 so as to enable ease of labelling,
handling and storage~ Thus, side wall portion 30 which is fabri~
cated in a straight sided cylindrical configuration so as to be
well-suited to the placement of a separate label on the outer
surface 60 thereof, is given a smooth matte finish along outer
surface 60. The smooth matte finish creates a smooth "satin-
like" surface in order to facilitate the adhesion of a label
which either has an adhesive backing or is secured with a
separate layer of adhesive placed directly upon surface 60. The
smooth matte finish is attained by treating the portion of the
mold which creates surface 60, first with a superfine sandblast
and then with a fine glass bead blast. Since it is the mold
which is so treated, each molded drum will emerge with the same
controlled surface finish.
In order to enhance the ability of drum 10 to be handled
manually, the exposed surface 62 of chime 46 is provided with
a medium-rough surface finish, and the medium-rough surface finish
preferably is extended onto the top end wall 22 continuously over
a contiguous annuIar area 64 of the top end wall 22, as illustrat-
ed in FIGS. 1, 2 and 6. The medium-rough finish creates a
granular-type surface which enables a worker to grasp the drum
10 along that surface without having the surface slip from the
grasp of gloved hands even when the surface or the gloved hands
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are wet. Thus, manual maneuverability is enhanced. The medium-
rough finish is achieved by treating the corresponding portion
of the mold which creates the drum 10, first with a superfine
sandblast and then with a No. 330 shot blast. Again, since
the mold is so treated, every drum will have-an identical sur-
face finish.
As best seen in FIGS. 1, 3 and 7, the outer surface 66
of the base 52 is provided with a coarse-rough surface finish.
Preferably, the coarse-rough surface finish is extended con-
tinuously along the contiguous surface portions 68 and 69 of
the side wall 14 and the bottom end wall 26. In this manner,
an extremely rough, almost knurled texture is provided so that
the drum will establish a firm frictional grip upon a support
surface, such as support surface 28. Thus, the drum will stand
firm upon a wooden pallet and will tend to resist skidding on
almost any floor surface encountered in shipment and storage.
In addition, the extended portions 68 and 69, together with
surface 66, provide for the anti-slip grip of gloved hands
during manual manipuIation of the drum. The coarse~rough
finish is attained by treating the corresponding area of the
mold, the treatment comprising a No. 14 grit blast. Again,
since the mold is so treated, each drum will have an identical
finish.
Turning now to FIGS. 7 and-8, as well as to FIGS. 1 and
2, drum 10 is provided with bung openings 70 and 72 in top end
wall 22, each bung opening being constructed to accept con-
ventional screw-threaded closures by means of a closure assembly,
shown at 80 in connection with bung opening 70. The closure
assembly for bung opening 72, though of smaller diameter, is
similar and does not require a separate illustration and des-
cription.
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The bung opening 70 itself extends through a boss 82 in
the top end wall 22. A separate threaded insert 84 having a
tubular body is fitted into the opening 70 and is secured therein
by complementary screw threads including an external thread 86 on
the insert 84 and an internal thread 88 in the boss 82. Thread
86 is a modified buttress thread having a thread profile which
includes a leading flank 90, facing the forward direction T of
the thread, and a trailing flank 92. Trailing flank 92 lies in
a plane P generally perpendicular to the forward direction T, and
the leading flank 90 makes an acute angle A with plane P and the
trailing flank 92. Such a thread configuration tends to keep the
insert 84 locked within the opening 70.
The insert 84 is itself provided with a threaded aperture
94 for receiving a conventional threaded closure 96 Closure 96
is selectively removable to gain access to the interior of the
drum, while insert 84 is more-or-less permanently installed in
the drum. The insert 84 is fabricated of a material which has
a toughness greater than the material of the drum 10. Thus, the
insert 84 is better able to withstand the repeated insertion and
removal of the closure 96. ~owever, should the insert 84 become
worn or otherwise damaged, it may be removed and replaced by
unthreading the insert from the opening 70, by means of the threads
86 and 88.
Preferably, the material of the insert 84 has a higher
melting point than the material of the drum 10 so that a complet-
ed insert may be placed in the drum mold during fabrication of
the drum and molded integral with the drum to establish an
assembled drum and insert. Where the drum 10 is molded of poly-
ethylene, the insert may be fabricated of another synthetic resin
material, such as nylon, which is tougher and has a higher melting
point than polyethylene.
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Insert 84 includes a flange 98 which abuts boss 82 to aid
in sealing the connection between the insert 84 and the top end
wall 22. Closure 96 also has a flange 100 which e~tends radially
outwardly and carries a depending lip 102. Upon insertion of
the closure 96 into the insert 84~ lip 102 is seated against an
annuIar sealing surface in the form of a seat 104 on the insert
to seal the threaded aperture 94. Closure 96 is provided with
a wrenching socket 105 for driving the closure during closing
and opening. An annular wall 106 is unitary with the insert 84
and extends upwardly beyond seat 104 to an outer edge 108.
Annular wall 106 is spaced laterally from seat 104 and outer
edge 108 is raised sufficiently such that upon seating the
closure 96 in the insert 84, as seen in FIG. 7, the outer
periphery 110 of the flange 100 of the closure 96 is located
closely adjacent to the annular wall 106 and the closure 96
is recessed beneath the outer edge 108. In this manner, access
to the closure 96 for operating the closure is limited to the
wrenching socket 104, with access to the outer periphery 110
being closed off. Thus, operation of the closure 96 by any tool
other than that specifically designed to enter wrenching socket
104 is precluded.
A protective cap 112 is placed over the closure 96 and
insert 84 and is secured in place by a clamping band 114 which
includes a bead 116 for engaging a complementary groove 118
in the flange 98 of the insert 84. The cap 112 seals the
closure 96 from surrounding contaminants.
It is to be understood that the above detailed des-
cription of an embodiment of the invention is provided by way
of example only. Various details of design and construction
may be modified without departing from the true spirit and scope
of the invention as set forth in the appended claims.
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