Threaded drum

Details Threaded drum Threaded drum

1998-03-10

2001-11-20

Cronin, Stephen K. (Department: 3727)

Receptacles

Closures

Removable closure guided in rotary movement

C220S601000, C220S634000, C215S044000, C215S329000

Reexamination Certificate

active

06318577

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to containers and, more particularly, to a threaded plastic drum closed by a threaded drum cover.
BACKGROUND OF THE INVENTION
In one form of a conventional shipping and storage container, an enlarged drum is used. The drum may be, for example, a fifty-five gallon drum. Such drums have found wide usage for shipping and storing liquid or granular products. For example, such drums have been used for storing food products and for storing hazardous products.
A typical drum includes a tubular sidewall closed at one end by a bottom wall and at another end by a top wall. Such containers may have a fiber board sidewall and metal top and bottom walls, or may be made entirely of metal. Drums of fiber board are generally not suitable for carrying liquids. While metal drums are, they tend to be expensive and heavy and are not usable in the food industry unless made of stainless steel.
Such drums are classified as open head drums or tight head drums. With a tight head drum the top wall is generally permanently affixed to the sidewall. The top wall includes relatively small openings for access to the interior of the drum. Conversely, an open head drum has a cover removably received thereon. Typically, the container is filled by removing the cover.
Tight head drums can offer certain advantages in transporting the drum. For example, a device known as a “parrot beak” is often used to transport the container about in a particular location. The parrot beak device clamps about a suitably configured junction between the top wall and sidewall for lifting the drum. With many open head drums, the parrot beak would be acting on the cover and a locking band. Depending on the interlocking relationship between the cover and the drum, forces resulting from use of the parrot beak might cause the cover to separate from the drum.
More recently, plastic drums have found wide acceptance. Customers often require that the drum be a one-piece drum having an integral cover to carry liquids. Such a drum is typically made by blow molding, which is a time consuming and expensive process. Open top drums are desirable in the fact that the user can access the drum contents more easily. However, open top drums can only be used to handle non-regulated liquids or solids.
The present invention is intended to solve one or more problems discussed above in a novel and simple manner.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided a threaded drum cover for selectively closing a unitary plastic open head drum to effectively provide a tight head drum.
Broadly, there is disclosed herein a threaded drum cover for selectively closing an open head drum. The drum comprises a tubular drum open at a top end defined by a threaded chime. The cover comprises a closure having a central circular wall of a size corresponding to that of the chime and a downwardly depending annular sidewall receivable radially outwardly of the chime. The sidewall includes radially inwardly directed threads for mating with a threaded chime to provide a tight head drum. A radially outwardly opening annular recess in the sidewall above the threads provides for external gripping of the tight head drum. The cover is of one piece plastic construction.
It is a feature of the invention to provide a circular ridge extending above the circular wall proximate an outer edge to define an upper circular ridge to aid in the external gripping. A second circular ridge extends upwardly from the circular wall radially inwardly of the outer circular ridge.
It is another feature of the invention that the threads comprise broken threads. The threads are provided at select circumferentially spaced locations of the sidewall.
It is an additional feature of the invention to provide a cylindrical reinforcing rib extending downwardly from the circular wall having an outer diameter slightly less than an inner diameter of a chime so that the sidewall and the rib sandwich the sidewall of the drum.
In accordance with another aspect of the invention there is disclosed a unitary plastic open head drum. The drum includes a cylindrical sidewall closed at a bottom end with a bottom wall and open at an upper end. A cylindrical chime is integrally formed with the sidewall at the open end. The chime comprises an annular wall having a thread extending helically about the annular wall. The thread has a depth of approximately ⅜ inch. The threaded drum cover is removably receivable on the cylindrical chime.
It is a feature of the invention that the thread in cross section has opposite top and bottom edges substantially perpendicular to the annular wall, an outer edge substantially perpendicular to the lower edge, and a sloped edge diagonally connecting the top edge and the outer edge. The sloped edge is sloped at an angle of approximately 30° to the top edge. Additionally, a radiused portion connects the bottom edge to the annular wall.
It is another feature of the invention that the chime has a diameter of approximately twenty-one inches.


REFERENCES:
patent: 3189072 (1965-06-01), Starr
patent: 3335923 (1967-08-01), Healy
patent: 3470927 (1969-10-01), Craig
patent: 4708258 (1987-11-01), Shaw et al.
patent: 4967926 (1990-11-01), Morris, Sr.
patent: 5096083 (1992-03-01), Shaw et al.
patent: 5560510 (1996-10-01), Grebenyuk et al.
patent: 5875915 (1999-03-01), Bradshaw et al.

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