Y-flanged Containers And Cover Members Therefor

Abstract

A closing cover member is provided for the mouth opening of an open-ended vessel such as a pail having a rim and made of a structural plastic material having nonrigid, flexibly distortable mechanical properties, such as high-density polyethylene, the pail having a peripheral rigidifying flange rising outwardly from the exterior of the sidewall commencing uniformly below the rim and forming an acute angle with the sidewall, the outer margin of the rigidifying flange terminating in a peripheral upwardly inturned short hook flange, and the cover member having a depending marginal flange wall terminating in a conic outwardly rising peripheral flange adapted to be forcibly nested upon the rigidifying flange with the edge engaged continuously under the hook flange, whereby axial pressure within the pail tends to enhance the sealing pressure along the contact areas of the outer and inner edges of the conic flange; either the conic flange or the rigidifying flange may be rigid, i.e. made of metal, if the other is polyethylene; where resistance to internal pressure is not required, roll-edge cover members may be snapped-on under the hook flange.

Description

This invention relates to open-ended containers provided with sealing covers having utility for the storage and transportation of liquid materials generally and foodstuffs specifically, and the invention is more particularly embodied in an improved sealable pail provided with a rim and a planar cover releasably seated upon the rim, the pail having a peripheral conic rigidifying flange rising outwardly below the rim and having an inturned continuous hook flange, and the cover having a peripheral flange or equivalent protuberance adapted to overlie the rigidifying flange when the cover is applied in closing relation on the pail mouth, the flanges cooperating to form a fluid-retaining sealing lock requiring no additional gasket or O-ring.

Containers constructed according to the invention when made of a nonrigid, flexibly distortable material such as high-density linear polyethylene and provided with a planar cover member of the same or similar material, or even of a relatively rigid material such as metal, strongly resist internal pressures and fluid surges, permitting stacking and shipping of such containers without risk of loss of seal or removal of the cover under usual handling conditions, yet may be readily opened by manual stripping of the cover starting at any part of its periphery. The reinforcement provided by the rigidifying flange maintains the shape of the container mouth opening excellently in handling and pouring.

Heretofore the retention of a releasable planar cover member made of a nonrigid, flexibly distortable material fitted on the open end of a container has depended either on axially engaging an inward bead edge carried by a depending peripheral flange of the cover to hook under an outwardly extending bead or projection of the rim of the container, or on pressing an annular groove defined by continuous sidewalls of an annularly raised peripheral portion of the cover about the edges of the open end. The sealing action in either arrangement depends on the adhesion of a radially distended peripheral portion of the cover to the exterior surface of the end portion of the container. While the holding effect provided by such covers in smaller sizes of containers subjected to gentle handling has proven adequate, the nature of the seal permits any moderate increase in internal pressure or occurence of a fluid surge to lift the cover, causing leakage. Furthermore, any downward movement of the container in handling causing the exterior to strike an obstacle may inadvertently strip the cover by applying lifting force along some part of its periphery. In addition, radial squeezing may so distort the rim despite provision of an offset in the container sidewall as to make the seal ineffective along the distorted sectors unless the thickness of the parts is very considerably increased.

I have found that a novel and highly advantageous locking seal may be provided for an open-ended container wherein the sealing action does not depend on the adhesion of a distended annular portion of the cover, but rather on the radial compressive strength of a peripheral flange portion of the cover which is seated into and is gripped between the exterior of the container and a hook flange joined with the outer end of a rigidifying annular conic flange rising outwardly from the container sidewall at an acute angle. This arrangement transfers the axial load on the cover resulting from internal fluid pressure to the seated annular flange, and by resolution of the component forces increases the radial horizontal pressure between the cover flange and the container, thus enhancing the sealing action. In addition, due to the fact that the nested and interlocked annular flanges of the container and the cover cooperate to increase radial stiffness of the closed container, its resistance to deformation by lateral shocks is greatly improved as compared with prior art forms. Since no part of the cover projects radially beyond the rigidifying flange, inadvertent release of the cover as a result of vertical movement cannot occur. Finally, the provision of the integral rigidifying flange rising outwardly below the mouth of the container at an acute angle and terminating in a hook flange at about the level of the rim tends to greatly stiffen and maintain the cross section of the open end in filling and pouring.

Essentially, therefore, the invention consists in providing, an open end container formed as a hollow body having an enclosing sidewall terminating as a rim defining a mouth opening, a peripheral rigidifying flange integral with the container sidewall and rising outwardly below the rim at an acute angle preferably about 45.degree., the flange terminating in a continuous inturned hook flange disposed at about the level of the rim, and a mating cover member having an intermediate planar portion connecting with a continuous rim-girdling depending flange forming a junction at its lower end with the inward margin of a peripheral sealing flange extension of annular conic form, the sealing flange being of such shape and inclination that its under surface may be axially nested upon the upper surface of the rigidifying flange when the hook flange has been forcibly flexed outwardly by insertion of the cover margin to effect a "snap-on" locking engagement under the hook flange, the inner margin of the sealing flange being pressed tightly against the container exterior to effect a fluidtight seal.

In the construction of a container which may be a pail by a molding operation according to the invention, using for example, high-density linear polyethylene, the core mold is provided with a slight taper in the sidewall and the exterior mold is provided with a break plane intersecting the junction of the rigidifying flange with the hook flange. In molding the cover of polyethylene or similar flexibly distortable material, the peripheral sealing flange is shaped to conform to the plan form of the rigidifying flange and the rim-girdling depending flange is shaped to closely engage the exterior of the rim, i.e., the plan form will be generally either circular, or rectangular with rounded corners. The cover member may also be constructed, according to one alternative, with the intermediate portion axially depressed below the level of the rim, by providing two depending flanges radially spaced and forming an inverted channel portion, defining an upward groove having an axial extent such that the rim is seated in the groove bottom when the sealing flange is nested upon the rigidifying flange.

The container may alternatively be closed by using a relatively simple sheet member shaped as a disc or to the plan form of the container, or as a planar member having a depending peripheral sidewall carrying an outward bead which may be engaged under the hook flange to effect covering; such cover members however would provide less effective sealing, and the enhanced sealing described for the conically flanged cover members would not be present. Such cover members may be used where the fluidtight sealing action is not necessary and where handling is gentle.

It is entirely feasible to construct the container of metal or other rigid material having a cover molded of a flexibly distortable material, or vice versa, provided only that at least one of the rigidifying flange and the sealing flange have the required distortability when the cover is axially pressed down to engage its margin inside the hook flange.

A preferred embodiment of a container constructed according to the invention having utility as a shipping pail will be described hereinafter, in conjunction with the accompanying drawing, wherein:

FIG. 1 is a perspective view showing the cover at an initial stage of its removal from the container mouth opening;

FIG. 2 is a perspective view showing handling and pouring of the pail contents from the wide mouth opening;

FIG. 3 is an axial diametral section in enlarged scale taken on line 3-3 of FIG. 1 showing the engagement of the cover in closing relation on the rim and locked with the rigidifying flange;

FIG. 4 is a view similar to FIG. 3 showing the cover axially separated at the position of initially engaging the rim;

FIG. 5 is an analytic diagram relating to FIG. 3 illustrating sealing force and locking action;

FIG. 6 is a section similar to FIG. 3 showing a cover modified to provide an inverted rim-engaging channel;

FIG. 7 is a cross-sectional view showing a modified shorter rigidifying flange disposed at a larger acute angle wherein the container is made of metal and the cover of polyethylene; and

FIGS. 8 and 9 show alternative cover members and rim heights employing a disc cover and a cap cover.

Referring to the drawing, a container or pail generally designated 10 having a flat bottom wall 11 is formed with an upwardly extending sidewall 12 shaped as a frustum of a cone, having a wall taper of a few degrees, the sidewall being formed with an offset portion 13 providing improved radial wall rigidity. The upper end of the sidewall terminates in a rim 14.

Below the rim 14 a continuous peripheral rigidifying flange 15 of annular plan form extends integrally from the container sidewall at a junction 16 therewith, rising at an acute angle designated .phi. which may range from about 15 to about 75.degree. with respect to the sidewall, a preferred angle as shown being about 45.degree.. The outer margin 17 of the flange 15 carries an upwardly inturned edge flange 18 having a blunt marginal edge 19 and a conic annular surface 20 disposed to provide a contained angle of 90.degree. or slightly less than 90.degree. with respect to the upper surface 21 of the rigidifying flange. The upper margin of the edge flange is in a plane disposed close to the plane of the rim 14, or preferably slightly below it.

The interior portion 22 of the container between the rim 14 and the junction 16 is preferably formed with a reduced taper and may be nearly vertical, or may be provided with a small taper opposite to that of the interior of the sidewall 12, to facilitate applying or removing the cover generally designated 23. The container is preferably molded of high-density linear polyethylene or other structural material which is similarly flexibly distortable, i.e. having a capacity of returning to its original shape after release of a limited deforming pressure. The cover 23 may be molded, as shown, of the same or similar material, and is provided with an intermediate planar portion 24 which may be disclike, or slightly dished inwardly as shown.

A depending flange 25 defining the periphery of the intermediate portion 24 is so dimensioned that the inner surface 26 may be axially forced into close engagement about the rim and sidewall portion 22. The lower margin 27 of flange 25 is formed with a lateral nose or inward continuous projection disposed at the same diametral distance from the container axis as the surface 26, or preferably at a slightly lesser radius. The flange is integral with a peripheral sealing flange 28 having conic annular form, the undersurface 29 of which is disposed at about the same or a slightly greater angle than is the surface 21. As shown in FIGS. 3 and 6, the angular relationship should be such that preferably the sealing flange seats in nested relation upon the upper surface 21 of the rigidifying flange with a small clearance between the adjacent conic surfaces in the vicinity of junction 16.

The flange 28 has a length as measured along a radial element of the generating cone which is a multiple of the thickness of the flange, to provide sufficient flexure to permit axial insertion under the flange surface 20. The distance between the outermost marginal edge 30 of the flange 28, which is shaped to a rounded profile, and the inward projection 27, is made slightly larger than the greatest distance between the flange surface 20 and the exterior surface 22 so that insertion of flange 28 causes a slight distension outwardly of hook flange 18. It has been found that injection molding methods favor the inherent radial contraction of marginal edge 27 so that deliberate provision in the making of the molds may be unnecessary to secure an inward protuberance. It is to be understood that compressive sealing may be obtained even when the inner margin of flange 28 is flush with the internal surface of flange 25.

As may best be seen from FIG. 4, the horizontal extent of flange 28 between the marginal edge portions 27 and 30 is larger, by the distance d, than the minimum horizontal distance between the nose 19 of hook flange 18 and the exterior sidewall 22. Consequently, axial engagement of the cover will tend to inwardly distort the container rim 14 as edge 27 slides down along the outer surface 22, and when edge 30 encounters the nose 19 the flange 28 will tend to be flexed as edge 30 lifts due to interference, along a sector being forced into locking engagement; flange 18 will be distended along such sector until edge 30 has seated undersurface 20 in contact therewith.

In the seated position of cover 23 its sealing flange 28 will therefore be under radial compressive stress while rigidifying flange 15 will be under slight tensile stress. Referring to the stress diagram, FIG. 5, the effect of internal pressure within the closed container is to apply a vertical axial load, which exerts a force F along a unit sectoral length, transmitted by tension link 125 representing the depending flange 25. Since the materials are flexibly distortable, the section cannot strictly be analyzed as though the structural elements were pin-jointed linkages; however, use of this method will at least serve to illustrate the locking and sealing actions enhanced by internal pressure.

The sectoral element 128 of the sealing flange may be taken as an end-loaded strut which is pivotally held at one end by a frame 120 and bearing in free sliding relationship against vertical frame 122 at its other end, which is pin connected to the end of tension link 125. When the angle between the elements 125 and 128 is .phi., the compressive load is F/Cos .phi., the horizontal sealing pressure H against frame 122 is F.Tan .phi., and the tension load T in the structural member 115 acting along line b-b is F/Cos .phi.. The total compressive load in the sealing flange, as well as the sealing pressure, will be increased by the contribution due to flexing of flange 18 resulting from initial seating of the cover.

When .phi. is 45.degree., the horizontal sealing pressure H exerted between marginal edge 27 and the container sidewall will be substantially equal to the axial load F carried by the flange 25. Since the area of contact along edge 27 is relatively small, the unit sealing pressure developed between contiguous surfaces is greatly increased as compared with the unit internal pressure which produces the axial load F. At the same time, the unit sealing pressure exerted between the edge 30 and the surface 20 will be even higher, since at 45.degree. the magnitude of F/Cos .phi. is about 1.4F.

The line of action of the compressive stress, designated z-z, will tend to make a slight angle with respect to the upper surface 21 as the edge 27 is lifted slightly away from junction 16 due to distortions resulting from the axial load. The rigidifying flange will tend to elongate slightly and because of the finite distance x between the line z-z and the medial tension line b-b in the rigidifying flange, a torque will be exerted tending to spread the flange 18. However, due to the favorable beam strength of the latter even at moderate wall thicknesses, considerable internal pressure may be resisted without noticeable distortion.

In general, the containers according to the invention will be used with internal pressures not greatly different from atmospheric, and variations therefrom within the container will in part be taken up by flexing of the intermediate portion 24. Fluid surges and upending of filled containers however will produce local internal pressure differences either above or below atmospheric, and the efficacy of seal enhancing in resisting loss of fluid under such disturbances is excellent.

When filled containers are to be shipped in stacked grouping, the alternative cover member of FIG. 6 is preferred, wherein an additional flange 32 extending upwardly is provided inwardly of flange 25, the flanges being joined by a rounded annular portion 33 overlying the rim 14. Due to taper of the sidewall, the lower end will seat inwardly of sidewall 32 upon shelf 34 formed at the junction of intermediate planar portion 24 with the flange 32. It will be evident that large axial loads applied tending to press annular portion 33 down on the rim will have little effect since sidewall 12 is radially stiffened and gains high resistance to buckling or crushing due to support by closely engaging flanges 25 and 32. Any increase in internal pressure resulting from the axial load of stacked pails and contents acts on the annular undersurface of portion 33, tending to lift this area and consequently enhancing the sealing pressure on edge 27.

When angle .phi. is made smaller, the horizontal sealing pressure H and the sealing flange compressive stress C are each diminished while use of angles greater than 45.degree. tends to increase both H and C and to bring them to a more nearly equal higher value. When the container wall is rigid, as shown in FIG. 7, an angle .phi. which may be as large as 75.degree. is practically feasible when the compressive strength of the flange 28 is made suitably large.

If the internal pressure of the container of FIG. 3 should fall considerably below atmospheric, the axial load F is reversed, and the undersurface 31 of the cover will be compressed against rim 14. Radial inward distortion produced in the marginal area of the cover portion 24 will develop tension in flange 25, consequently enhancing the sealing pressure H on sidewall 22.

Throughout the foregoing discussion it has been shown that the cover member 23 is securely locked and sealed whether internal pressure is above or below atmospheric. It is nevertheless easy to remove the cover once any sectoral portion of edge 30 has been disengaged from under flange 18. To facilitate stripping the cover from the mouth opening, an integral tab is provided as shown in FIG. 1, attached along a short arcuate length of the upper side of flange 28 adjacent edge 30. When the tab is grasped and pulled upwardly and inwardly until some part of edge 30 is exposed and a gap 36 is provided, adjoining sectoral portions of flange 28 may be freed by axial pull on them, or by prying them free with a tool slid under the surface 29.

In those use applications where a cover member providing low resistance to internal pressure may be substituted, a disc having a peripheral edge 37 shown in FIG. 8 is shaped to the plan of the hook flange 18, so that edge 37 may be sectorally advanced in engagement under the surface 20. The level of rim 14 is advantageously either slightly lower than surface 20 or at nearly the same level so that the marginal zone may be flexed slightly and pressed upon rim 14. Where the rim 14 lies in a plane considerably above the plane of surface 20, the cap cover of FIG. 9 is used, being provided with a depending sidewall 25 and a bead or other outward continuous protuberance 38 shaped to snap under the nose 19 and spring outwardly against surface 20.

It is to be understood that although the description has been directed to embodiments having tapering enclosing sidewalls terminating in a rim whose diameter is the largest diameter of the body, it is entirely feasible to construct containers of constant cross-sectional dimensions along their axial length, i.e. to provide cover members which in effect form removable end walls for cylindrical bodies such as tubes or pipes.

Claims

I claim:

1. A container and a cover member therefor formed of a flexibly distortable structural material, said container comprising a hollow body having an enclosing sidewall and a closing bottom wall, the upper end of said sidewall terminating in a rim defining a mouth opening, a rigidifying flange member of conic annular form integrally joined with said sidewall along a junction spaced below said rim, rising outwardly at an acute angle, and terminating in an upwardly inturned annular hook flange, said hook flange having an inner margin spaced from said rim, said cover member having a mouth-closing portion and a depending sidewall portion carrying an annular conic sealing flange adapted to be nested upon said rigidifying flange when said cover member is forcibly affixed in closing relation over said mouth opening, said conic sealing flange having an outer margin adapted to be distortably received in locking engagement under said hook flange and having an inner margin adapted to sealingly engage said sidewall of said container proximal to said junction and to exert increased sealing pressure on said sidewall in response to axial force tending to lift said cover member.

2. A container and cover member as set forth in claim 1 wherein said mouth closing portion conformably contacts said rim when said cover member is affixed in closing relation.

3. A container and cover member as set forth in claim 1 wherein the inner margin of said annular conic sealing flange projects radially inwardly of said depending sidewall and forms a sealing protuberance.

4. A container and cover member as set forth in claim 1 wherein said inner margin of said hook flange lies in a plane spaced adjacently below the plane of said rim.

5. A container and cover member as set forth in claim 1 wherein the inner margin of said hook flange lies in a plane spaced slightly above the plane of said rim.

6. A container and cover member as set forth in claim 3 wherein said acute angle is between about 15.degree. and about 75.degree..

7. A container and cover member as set forth in claim 6 wherein said acute angle is about 45.degree..

8. A container and cover member as set forth in claim 6 wherein said hook flange has an undersurface which is inclined to the upper surface of said rigidifying flange with an included angle which is a right angle or slightly less than a right angle.

9. A container and cover member as set forth in claim 2 wherein said mouth closing portion of said cover member comprises a central planar portion, an upwardly extending wall portion integrally joined with said planar portion, an annular rounded portion merging with said upwardly extending wall portion and with said depending sidewall portion, said annular rounded portion having an undersurface conformably contacting said rim when said conic sealing flange is seated with its outer margin locked under said hook flange.

10. A container as set forth in claim 3 wherein said mouth opening is circular.

11. A container and cover member as set forth in claim 3 wherein said mouth opening is rectangular in plan view having rounded corners, and said rigidifying flange comprises straight strip side portions merging with conic corner portions.

12. A container and cover member as set forth in claim 3 wherein said rim has the largest diameter of said hollow body.

13. A container and cover member therefor as set forth in claim 3 wherein said hollow body has constant cross-sectional dimensions between said junction and said rim.