Container And Cover Therefor

Abstract

The invention is concerned with drum-type containers, particularly plastic containers having flexible covers which form a fluid-tight seal by means of a locking action which holds the cover in positive engagement with the container.

Description

DESCRIPTION OF THE INVENTION

This invention relates to drum-like containers having flexible covers which are engaged in a positive locking manner with the containers.

Lidded tub or drum-like containers fabricated from plastic materials, such as polyethylene, polystyrene, etc., are finding increasing use in the food and chemical industries. The size of such containers has steadily increased with improvement in the quality of plastic materials, and in the introduction of new materials so that 5 gallon or 50 pound containers are now available. The closing and sealing of such containers generally relies upon the greater elasticity of plastics as compared with metal. In small containers an interference fit between a lid and container may be sufficient. In larger containers, there is usually an internal bead on the lid which engages an external bead near the top of the container wall. Either the lid or the container body or both distort to allow the beads to pass into locking engagement.

The disadvantage of this means of maintaining a lid on a container is that external and internal forces frequently cause distortion of the mating members with the result that they do not form a tight seal. If the distortion is extreme the lids may even come completely off. Such forces may be due to expansion of the contents or from the weight of other containers when they are stacked.

In the present invention a structure is provided which applies a positive constricting force to the skirt of the lid, locking the lid in engagement with the wall of the container even when subjected to forces which tend to distort the lid skirt and/or container, and would otherwise cause them to disengage.

It is therefore an object of the invention to provide a drum-type container having a cover which forms a fluid-tight seal by the action of integrally formed closing means.

It is a further object to provide a plastic container having a positive locking means which is quick acting and requires only small motion.

Other objects and advantages will be apparent to one skilled in the art from reading the following description of the invention in conjunction with the accompanying drawings, wherein:

FIG. 1 is an exploded perspective view showing the top of the container and the cover in the relative positions in which the cover is applied, with a portion of the rim of each broken away.

FIG. 2 is a sectional view showing the container and cover in contact in the initial or unlocked position.

FIG. 3 is a sectional view with the cover in the closed or locked position after rotation in the direction of the large arrow.

The invention comprises generally a circular container having an external circumferential bead at or near the top rim of the wall, and a flexible cover having a generally horizontal body of approximately the same size as the circular opening of the container, and having a circumferentially downwardly directed wall carrying on its inner surface a bead adapted to engage the bead on the container wall, and carrying a plurality of outwardly directed lugs for engagement with a plurality of cam locking means carried on a circumferential flange, or a plurality of supports, projecting from and integral with the outside of the wall of the container.

Referring to the drawings, the circular container 10 has a generally vertical side wall 11 having a slight taper, the top of which is thickened externally to form a rim 12. Rim 12 has a lower surface 12a sloping downward from the outer extremity of the rim to the outer surface of the side wall and a grooved upper surface 12b. Spaced from rim 12 and integral with wall 11 is an external circumferential flange 13 having a generally horizontal upper surface carrying a plurality of spaced abutments 14 of which the leading end 14a, in relation to the direction of rotation of the cover in closing, is further from the side wall than the trailing end 14b. The inner side of the abutments is undercut slightly to provide an overhanging lip 14c. Reinforcing gussets 13a in the angle between the lower surface of flange 13 and wall 11 provide rigidity to the flange. The illustrated cover 20 has a horizontal body portion 21 with a raised rim 22 formed by an inner wall 21a, an upper wall 22a, and an outer vertical wall 23 which has partial inward thickening to form bead 24 having a sloping surface 24a adapted to engage surface 12a on rim 12. Rim 22 and walls 21a and 23 together define an inverted peripheral channel portion which includes a continuous corrugation 22a' adapted to sealingly seat in the grooved edge 12b of the container side wall 11 when the container is closed. On the outer surface at the lower extremity of wall 23 is a plurality of outwardly directed locking lugs 25 suitably spaced and shaped to engage abutments 14 in a wedging action when the cover is rotated in relation to the container in the direction indicated by the large arrow in FIG. 3. Reinforcing gussets 26 are provided between locking lugs 25 and wall 23. A pair of diametrically opposed locking lugs 25 is provided with projections 25a for tightening the lid by hand pressure or engagement with a cooperating machine part in the automated loading and sealing of containers.

The operation of applying the cover to the container will now be described. Lid 20 is placed on the container with rim 22 in loose engagement with the top of wall 11. In this operation locking lugs 25 will be in position between abutments 14 as seen in FIG. 2. The dotted position of wall 23 indicates the position which it has to pass through in order for bead 24 to clear the shoulder on rim 12. The lid is then pressed down and flexed by inward pressure on wall 23 in the direction indicated by the small curved arrow on FIG. 3, and simultaneously rotated in the direction of the large arrow of FIG. 3. The inward pressure may be applied by hand although especially in the case of larger containers, it may be desirable to use mechanical means to exert pressure at a plurality of points or over the entire circumference of wall 23. This will achieve a positive engagement between surfaces 12a and 24a of the rim and the cover bead, respectively, and between the lower surface of rim 22 and the grooved edge 12b of wall 11, as the outer edge of lugs 25 engage the inner surface of abutments 14 in a wedging action. In the final closed position, the cover is firmly held in locking arrangement with the container in such a way as to prevent distortion of the peripheral structure of the cover and consequent breaking of the seal even when filled containers are stacked on top of each other.

It will be apparent that variations from the specific structure described can be used without departing from the scope of the invention. For example, individual supports may be provided for abutments 14 instead of the circumferential flange. In addition the actual configuration of the lugs and abutments is not critical so long as they cooperate to provide a wedging and locking action.

The materials of construction are varied and include any suitable plastic materials having the necessary rigidity and flexibility characteristics, of which polystyrene and polyethylene are typical examples. The preferred plastics are the relatively rigid ones such as high impact polystyrene. It is possible to practice the present invention by the use of a cover made from a suitable plastic material in conjunction with a container made from another material such as a metal but it is preferred to fabricate both the cover and the container from plastic materials.

Claims

I claim:

1. A flexible closure lid for use with a drum-type container having a circular opening formed by a generally vertical side wall having at its upper end an external rim and below said rim and disposed therefrom a plurality of upstanding abutments supported on said side wall and in spaced relation thereto, said closure lid comprising a circular, generally horizontal, body portion and a peripheral rim portion, said rim portion extending upward from said body portion providing an inner wall thence outwardly providing an upper wall and then downwardly providing an outer wall substantially parallel to and in spaced relationship to the inner wall, the inner surface of said outer wall being provided with a circumferential bead adapted for engagement below said external rim, and the outer surface of said outer wall being provided adjacent its lower extremity with means adapted for wedging engagement with said abutments.

2. A closure lid according to claim 1 in which said means adapted for wedging engagement comprises a plurality of spaced horizontal lugs.

3. A closure lid according to claim 1 in which the lower surface of said upper wall is convex in shape.

4. A container comprising a body portion and a cover portion therefor adapted to form a fluid tight seal between the body portion and the cover portion by rotation of the cover relative to the body while in positive contact therewith, comprising:

a. a drum-type body portion having a circular opening formed by a generally vertical side wall having at its upper end an external rim and below said rim and disposed therefrom a plurality of upstanding abutments supported on the side wall and in spaced relation thereto, and

b. a flexible cover comprising a circular, generally horizontal body portion and a peripheral rim portion, said rim portion extending upward from said body portion providing an inner wall thence outwardly providing an upper wall and then downwardly providing an outer wall substantially parallel to and in spaced relationship to the inner wall, the inner surface of said outer wall being provided with a circumferential bead adapted for engagement below said external rim and the outer surface of said outer wall being provided adjacent its lower extremity with means adapted for wedging engagement with said abutments.

5. A container according to claim 4 in which said abutments extend normally from the upper horizontal surface of a circumferential flange supported on said side wall.

6. A container according to claim 5 in which the leading ends of the abutments in relation to the direction of rotation of the cover when being applied are at a greater distance from the side wall than the trailing ends.

7. A container according to claim 4 in which the upper end of said side wall has a V-shaped groove and the lower surface of said upper wall of the rim portion of the cover has a convex shape adapted for sealing engagement with said V-shaped groove when the container is closed.

8. A container according to claim 4 in which at least one of said body portion and said cover is manufactured from a thermoplastic composition.

9. A container according to claim 4 in which at least one of said body portion and said cover is manufactured from impact polystyrene.