CLOSURE FOR A CONTAINER LID

Abstract

A single-piece, molded plastic closure is disclosed and is constructed and arranged for assembly into a container lid opening. The closure includes an annular side wall having a lid engaging portion and an end panel. The end panel is configured with an annular recessed section and an annular frustoconical section which surrounds the annular recessed section. When a vacuum is applied to the surface of the lid for movement of the container the lid may bow and affect the degree of engagement between the closure and the lid opening. The addition of the end panel offsets the effect of the vacuum and enhances the degree of engagement between the closure and the opening so as to prevent dislodgement of the closure during vacuum head movement of the container.

Description

BACKGROUND

In the container and closure art there are styles of closures which must be designed for removal from within a (container) lid opening and reinstalled back into the lid opening. In terms of use and handling of the container when the closure is installed, the tightness of the “fit” of the closure within the lid needs to be sufficient so as to prevent leakage of the product contents of the container during such use and handling. A closure-to-lid fit which is too tight may result in the closure being too difficult to remove and/or too difficult to reinstall and thereby unacceptable. If the closure-to-lid fit is not tight enough, then during use and handling there could be leakage of the product contents which is also unacceptable. One style of closure which is representative of the type described above is a molded plastic push-in or press-in (closure) plug for a plastic lid. By selection of appropriate materials and dimensions, a suitable or desired balance can be achieved for the degree or level of interference fit. If designed properly, at the higher end, the degree of interference fit is sufficient for sealing and at the lower end, the degree of interference fit still allows the plug to be removed (manually) and reinstalled.

A more specific example of the above style of closure is a tint plug for a paint container. The paint container typically includes a snap-on lid with a defined tint plug opening normally centered within the lid. The tint plug has a push-in or press-in construction such that it can be manually pressed into the plug opening which is defined within the lid. The installation can also be done by a machine or with machine assistance, and as desired, manually removed from and/or reinstalled in the defined plug opening of the lid. Typically, this style of tint plug includes a pull-ring bail for facilitating manual removal of the tint plug when desired.

The tint plug is removed using the pull-ring bail at the paint store so that the base paint which has been filled into the container can be tinted to the desired color. After tinting, the tint plug is reinstalled and the paint container is shaken to thoroughly mix the contents. During this mixing process, it is important that the tint plug maintain a sealed assembly in the lid so as to prevent leakage of the contents. Further, during this process, the tint plug (i.e. the closure) must be able to be removed and reinstalled. Since removal is done manually using the pull-ring bail, there needs to be a balance between the degree of interference fit for proper sealing and the degree of interference fit for ease of use involving removal and reinstallation. These two levels or degrees of interference fit are not independent functions or characteristics. There must be a balance between the two since modifying the degree of interference fit for one will have an effect on the other.

As a part of the initial container filling and lid closing process and movement of the filled paint container, particularly when part of an automated filling line, a vacuum pick up head may be used for transport and/or lifting of the paint container. The configuration specifics of the selected robotic and/or automation equipment is not critical to an understanding of the issue. A vacuum head is applied to some portion of the lid and this vacuum head encloses the outer surface of the tint plug. This vacuum head draws a suction and thereby creates a pressure difference between the one side of the tint plug and the opposite side of the tint plug. The same type of pressure difference could be created by a positive (i.e. above atmospheric) pressure on the inside of the container and the present of atmospheric pressure on the outside of the container. Whichever pressure difference condition might exist in the context of the present invention, there is a pressure difference across the tint plug (i.e. the closure) with the lower pressure being on the outside or on the outer surface of the tint plug.

If the degree of interference fit of the tint plug cannot withstand the applied vacuum and loosens or becomes dislodged, it is conceivable that the application of a vacuum over the loosened or dislodged tint plug will draw up or suck up paint from within the container. If paint enters the vacuum equipment, then the vacuum equipment could become damaged or at the very least need to be shut down and thoroughly cleaned. Even if paint is not drawn up into the vacuum equipment, if the tint plug is dislodged, the necessary handling and movement of the container can cause leakage of paint onto the lid and container. This still requires an additional paint clean-up step. If the tint plug becomes completely dislodged, it is conceivable that it might be lost as the container moves through the filling line.

In view of these potential problems as described above, the tint plug or similar closure, needs to be structurally configured to address these concerns when an elevated pressure difference exists across the closure. These concerns are addressed by the exemplary embodiment of the present invention.

SUMMARY

A closure for installation within a lid of a container is constructed and arranged to increase the degree of engagement force between the closure and a closure opening defined by the lid when there is a pressure difference across the closure. The closure opening defined by the lid receives the closure and there is contact or engagement between the two due to an interference fit. The lid may be of a plastic, snap-on design with an annular rim which fits over the upper edge of the container. In order to lessen the risk that the closure will loosen or become dislodged relative to the closure opening in the lid when there is a pressure difference across the closure, the closure of the exemplary embodiment is constructed and arranged with a novel end panel construction. This novel end panel construction deflects in response to a lower pressure on the outer surface of the closure. This deflection of the closure end panel, in response to a lower pressure across the outside surface of the closure, results in increasing the level or degree of engagement force at the point of engagement between the closure and the edge of the closure opening. This lower pressure which is seen by the outer surface of the closure may be due to a vacuum head being used on the lid for movement of the container. While there is an interference fit between the closure and the edge of the closure opening, the end panel causes a greater engagement or abutment force for this fit.

When the outer surface of the lid is exposed to this type of vacuum, the lid bows and that could create loosening or dislodgement of the closure, depending on the level of the vacuum. The typical type of vacuum head for robotic lifting or movement and the vacuum level which is applied needs to be sufficient for the desired movement or transport of the filled container. Any potential loosening of the closure within the opening is offset by the deflection of the end panel of the closure which increases its abutment force and thereby increases the resistance to removal of the closure aiding in its retention during the time that the vacuum is applied. When the vacuum is not present, the end panel does not increase the force normally needed to remove the closure. The removal of the closure is often by the use of a removal pull-ring bail or a lifting bail (handle) and this construction is not affected by the addition of the novel end panel.

Further forms, objects, features, aspects, benefits, advantages, and embodiments of the present invention will become apparent from a detailed description and drawings provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a closure according the exemplary embodiment of the present invention.

FIG. 2 is a front elevational view of the FIG. 1 closure.

FIG. 3 is a side elevational view, in full section, of the FIG. 1 closure as viewed along line 3-3 in FIG. 1.

FIG. 4 is a front elevational view, in full section, of the FIG. 1 closure as viewed along line 4-4 in FIG. 1.

FIG. 5 is a rear elevational view, in full section, of the FIG. 1 closure as viewed along line 5-5 in FIG. 1.

FIG. 6 is a front elevational view, in full section, of a lid which is constructed and arranged for receipt of the FIG. 1 closure.

FIG. 7 is a side elevational view of the FIG. 6 lid with the FIG. 1 closure installed.

FIG. 8 is a side elevational view, of the FIG. 7 assembly, as assembled to a container which is shown in partial form.

FIG. 9 is a diagrammatic illustration of the FIG. 8 assembly with a pressure difference applied across the FIG. 1 closure showing the bowing of the lid in response to the pressure.

FIG. 10 is a diagrammatic illustration of a vacuum head for use in movement of the FIG. 8 closure, lid and container assembly.

DESCRIPTION OF THE SELECTED EMBODIMENTS

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. One embodiment of the invention is shown in great detail, although it will be apparent to those skilled in the relevant art that some features that are not relevant to the present invention may not be shown for the sake of clarity.

Referring to FIGS. 1-5, there is illustrated a unitary closure 20 which in the exemplary embodiment is a single-piece, molded plastic component. The specific example being used for closure 20 is a tint plug for a paint container. For the exemplary embodiment, the paint container 22 is fitted with a snap-on lid 24, see FIG. 8. The lid 24 defines a receiving opening 26 for the closure 20, see FIG. 6.

For the exemplary embodiment, the paint container 22 is a generally cylindrical structure with a generally circular upper opening 28 and a closed lower panel (not illustrated). The upper opening 28 is defined by wall 30 which includes an annular lip 32 with a lower offset edge 34 for the snap-fit receipt of lid 24, see FIG. 8. In this exemplary embodiment, the container 22 is plastic and the snap-on lid 24 is plastic. The type or style of container represented by paint container 22 is typically filled with a base paint which is to be tinted to the desired color at the paint store. In order to more easily add the tint, closure 20 is provided. This allows tint to be added through the opening within the lid rather than having to remove the entire lid. Without closure 20 and the ability to remove closure 20 and then reinstall that closure, the paint store personnel would have to pry off the entire lid 24 and then reapply the lid before shaking to thoroughly mix the contents. Having a removable tint plug, i.e. closure 20, allows the paint store personnel to pull out the closure, using the pull-ring bail 36, add the tint and then reinstall the closure 20 by pushing it back into the receiving opening 26. The removal and reinstallation of the closure 20 may be performed as often as required in order to achieve the desired tinting of the base paint.

With continued reference to FIGS. 1-5, in addition to pull-ring bail 36, closure 20 further includes an annular side wall 42 and a lower end panel 44. Side wall 42 extends into an annular lip 46 which extends radially outwardly from the upper edge of side wall 42. The intersection of side wall 42 and end panel 44 is at the location of annular corner 48. The pull-ring bail 36 is integrally joined to the end panel. This construction is illustrated in FIGS. 1-5 and closure 20, in the exemplary embodiment, is a single-piece molded plastic component including pull-ring bail 36. In view of the single-piece molded plastic construction for closure 20, there is no specific boundary line to be drawn between end panel 44 and corner 48, for example, or between side wall 42 and lip 46, for example. Solely, for the purposes of this disclosure and the description of the exemplary embodiment, an arbitrary selection has been made to treat the radial lip 46 as a part of the side wall 42 and to treat the corner 48 as a part of the end panel 44. With this arbitrary selection and assignment, the annular side wall 42 is joined to the end panel 44 and the end panel includes the pull-ring bail 36. This is the construction of closure 20 as described and illustrated herein.

The orientation of closure 20 in FIGS. 1-5 shows the closure as it will appear in normal use within the paint container 22 in an upright orientation as it would normally appear. The upper surface of the closure is the outside or outer surface as it faces outwardly relative to the lid 24 when the lid 24 is snapped onto the container 22, see FIG. 8. The lower surface of the closure is the inside surface or inner surface and it faces inwardly relatively to lid 24 when the lid 24 is snapped onto container 22, see FIG. 8.

With continued reference to FIGS. 1-5, closure 20 defines a recessed interior space 50. The pull-ring bail 36 is positioned within interior space 50 and the upper most portion of pull-ring bail 36 is recessed below the upper surface 52 of lip 46. This arrangement lessens any risk of the pull-ring bail 36 being inadvertently caught or pulled free. Clearance is provided around the pull-ring bail 36 by interior space 50 for the finger or thumb of a user to be inserted for manual removal of closure 20 from opening 26. Reinstalling closure 20 into opening 26 is by pressing or pushing the closure 20 into the opening, also typically a manual procedure.

Side wall 42 has an inclined inner surface 56 providing a generally frustoconical shape which is substantially straight in axial section. The outer surface 58 of side wall 42 includes three differently shaped annular sections 60, 62 and 64 positioned between lip 46 and corner 48. Starting at the lower surface 66 of lip 46, the first annular section 60 is generally cylindrical. The next annular section 62 has a wedge shape in axial section or what might be described as a tapered ramp. Shelf portion 62a extends radially outwardly beyond the outer boundary of section 60. A short cylindrical portion 62b is next, leading into frustoconical portion 62c. The third annular section 64 has a generally cylindrical shape and extends from portion 62c to the start of corner 48.

The end panel 44 includes an annular panel portion 70 which is radially inwardly of corner 48. Panel portion 70 includes an annular ring shelf 72, an annular recessed section 74 and an annular frustoconical section 76 which extends between the inner edge of shelf 72 and the outer edge of section 74. Pull-ring bail 36 is joined to frustoconical section 76. In view of the single-piece, molded plastic construction of closure 20, the portions and sections of the end panel 44 do not have separately identifiable end points, edges, or ends. References to such are simply to try and convey that a particular portion or section does at some point transition into an adjacent portion or section, consistent with a single-piece construction.

Referring now to FIG. 6, a cross-sectional view of lid 24 is illustrated and represents a suitable lid for the exemplary embodiment. Lid 24 is annular and a single-piece component which is molded from plastic. Each portion and each section of lid 24 has a uniform annular form and is generally symmetrical about each diametral line. Lid 24 includes an annular outer rim 78 which is formed with an annular (inverted) channel 80. The outer wall 82 of rim 78 includes an offset, radially inward lip 84 for a snap-fit beneath edge 34 of the lip 32 of the container 22. Annular lip 32 fits up into annular channel 80 when the lid 24 is properly snapped over the lip 32 of the container 22. With plastics used for the fabrication of the lid and of the container, there is an ability for those components to flex and deflect, but even with this ability, the dimensional sizing and tolerances of these two components is such so as to establish a tight and secure snap-fit assembly. This tight and secure snap-fit assembly is important in order to prevent leakage, particularly when the closed container is subjected to being shaken as a part of the process of thoroughly mixing the tint with the base paint.

Lid 24 defines opening 26 and concentrically surrounding opening 26 is a radially outward, annular recess shelf 90. In the exemplary embodiment, the opening 26 is generally centered in the lid 24. This construction is what is typically found in actual use. The axial depth of the recess of shelf 90 relative to upper surface 92 of lid 24 which defines opening 26 is approximately equal to the axial height or thickness of lip 46 of closure 20. When closure 20 is pressed into opening 26 and fully seated, the lower surface 66 of lip 46 should abut up against shelf 90. If there is any noticeable separation at this interface, it means that the closure 20 has not been fully pressed into opening 26 of lid 24. In this assembled condition, the upper surface 52 of closure 20 is substantially flush with the upper surface 92. The axial thickness of shelf 90 is captured between surface 66 and shelf portion 62a. This means that the axial height of section 60 is substantially the same as the axial thickness of shelf 90 for the described assembly of closure 20 into opening 26. The wedge-shaped construction of section 62 provides a lead-in and tapered ramp for ease of installing the closure 20. As the inner annular edge 94 of shelf 90 which defines opening 26 engages section 62, the fit becomes tighter until the shelf 90 snaps into and around section 60. Removal of closure 20 from lid 24 requires some degree of plastic deflection as the inner edge 94 of shelf 90 must travel past the radially outward, annular edge of shelf portion 62a. Annular edge 94 includes a slight, frustoconical taper as is illustrated in FIG. 6. This initial assembly of the closure 20 into opening 26 is illustrated in FIG. 7. The assembly of the lid 24, closure 20 and container 22 is illustrated in FIG. 8.

The FIG. 8 assembly positions the closure 20 in tight sealing engagement (i.e. surface-to-surface abutment) with the inner surface/edge 94 of the receiving opening 26. The tightness of the initial fit which depends on the degree of dimensional interference needs to be sufficient to prevent loosening or dislodgement of the closure which would result in leakage of the product contents of the container which in the exemplary embodiment is paint.

As discussed in the Background, the movement and lifting of containers filled or a least partially filled with paint during the filling and closing process may include the use of robotics and vacuum lifting/handling equipment. A vacuum head 100 for lifting and/or movement of the container 22 is diagrammatically illustrated in FIG. 10. While the size, type and location of the vacuum head 100 are not critical to this part of the description, what is important is that the vacuum head surrounds the closure 20 and seals against the upper surface of the lid 24. Some degree or level of vacuum suction by means of the vacuum head 100 is necessary to be able to move and/or lift the container 22 using this type of robotics or handling equipment. Since the closure 20 is preferably centered in the lid 24, and since the vacuum head 100 should be generally centered on the lid in order to balance the weight of the container, the result will be for the vacuum head to enclose and seal around the closure 20. When the vacuum is pulled for the desired handling of the container, a pressure difference is created across the closure. The outer surface of the closure 20 is exposed to a lower pressure (vacuum) compared to the inner surface of the closure 20 which is exposed to at or near atmospheric pressure. While the interior pressure of the container might change depending on the nature of the contents and depending on the temperature, the consequence will still be to always have an equal (both sides atmospheric) or lower pressure present at the outer surface of the closure. When a vacuum is pulled on the lid 24 for the purpose of movement and/or lifting of the container, the pressure difference across the closure 20 will normally be high enough that the end panel 44 deflects in response to the pressure difference. The addition of end panel 44 as a part of closure 20 and the configuration of end panel 44 are important because of the likelihood of having a pressure difference applied across the closure. Without end panel 44 and specifically without the construction and arrangement of sections 74 and 76, the applied pressure difference could loosen or dislodge the closure 20. With the improvement provided by end panel 44, there is an increased contact force or engagement force applied to the area of abutment of the closure against the inner surface of opening 26.

While the suction due to the applied vacuum would otherwise tend to loosen the fit between the closure 20 and the opening 26, the deflection of end panel 44 creates an increased abutment force which offsets at least some of any loosening effect due to the applied vacuum (suction) and the resulting pressure difference across the closure.

Referring now to FIG. 9, the consequences of the application of a suction force due to the use of a vacuum head are diagrammatically illustrated. The vacuum head is not shown in FIG. 9, but the consequences of the pressure difference are shown in terms of the lid deflection (the bowed shape) and the movement/deflection of end panel 44, specifically the deflection of recessed section 74. In order to create a sufficient suction force on lid 24 for lifting or for moving the container 22, the size and material of lid 24 is such that it causes the lid to bow up into a convex shape on the outer surface and a concave shape on the inner surface. The deflection and bowed shape of the lid 24 can affect the fit between the closure 20 and the opening 26. Even if any loosening of the closure 20 within the opening 26 due to the bowed shape of the lid is not significant, this effect or result is combined with the suction force which is applied at the same time to closure 20. The applied suction force tries to pull the closure 20 out of opening 26 whether or not there is any dimensional change to the opening resulting from the bowing of the lid.

The design of end panel 44 is such that as the suction force is applied to the closure, its effect is initially offset by deflection of the recessed section 74. The key though is as the recessed section 74 deflects it causes an increase in the abutment force between closure 20 and the inner edge of opening 26. This increase in abutment force causes closure 20 to remain securely in position in opening 26 without any level or degree of closure loosening which would result in leakage of the container contents and without actual dislodgement of the closure from within opening 26. This increase in abutment force of the engagement between closure 20 and the inner edge of opening 26 is generally dependent on or proportional to the suction force and pressure difference across the closure. When the suction force is removed, the closure returns to its normal static condition and can be manually removed from the lid and reinstalled into the lid as intended as part of the tinting process.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes, equivalents, and modifications that come within the spirit of the inventions defined by following claims are desired to be protected. All publications, patents, and patent applications cited in this specification are herein incorporated by reference as if each individual publication, patent, or patent application were specifically and individually indicated to be incorporated by reference and set forth in its entirety herein.

Claims

1. A single-piece, molded plastic closure for assembly into a container lid opening, said closure comprising: an annular side wall having a lid engaging portion; andan end panel having an annular recessed section and an annular frustoconical section which surrounds said annular recessed section.

2. The closure of claim 1 wherein said side wall further includes a tapered ramp portion.

3. The closure of claim 2 wherein said end panel further includes an annular shelf portion which surrounds said frustoconical section.

4. The closure of claim 3 which further includes a pull-ring bail which is joined to said frustoconical section.

5. The closure of claim 4 wherein said end panel is constructed and arranged to deflect in response to a pressure difference established across opposite surfaces of said end panel.

6. The closure of claim 5 wherein said shelf portion is joined with said side wall by way of an annular corner.

7. The closure of claim 6 wherein said side wall includes an inner surface which has a frustoconical shape.

8. The closure of claim 1 wherein said end panel further includes an annular shelf portion which surrounds said frustoconical section.

9. The closure of claim 8 wherein said shelf portion is joined with said side wall by way of an annular corner.

10. The closure of claim 1 which further includes a pull-ring bail.

11. The closure of claim 10 wherein said pull-ring bail is joined to said frustoconical section.

12. The closure of claim 1 wherein said end panel is constructed and arranged to deflect in response to a pressure difference established across opposite surfaces of said end panel.

13. The closure of claim 1 wherein said side wall includes an inner surface which has a frustoconical shape.

14. In combination: a plastic lid for a container comprising an annular rim used for attachment to said container and defining an opening for receipt of a closure; anda single-piece, molded plastic closure for assembly into said lid, said closure comprising: an annular side wall having a lid engaging portion;an end panel having an annular recessed section and an annular frustoconical section which surrounds said annular recessed section.

15. The combination of claim 14 wherein said opening is surrounded by an annular shelf which is recessed below an upper surface of said lid.

16. The combination of claim 15 wherein said opening includes an inner annular edge which is in contact with said lid engaging portion.

17. The combination of claim 16 wherein said closure includes an annular lip which overlaps said shelf.

18. The combination of claim 17 wherein said lid is constructed and arranged to deflect into a bowed shape in response to a suction force applied to the upper surface of said lid.

19. The combination of claim 18 wherein said end panel is constructed and arranged to deflect in response to said suction force.

20. A plug closure for insertion into a container lid opening, said plug closure comprising: a body defining an interior space and being constructed and arranged to establish a contact force against said container lid upon insertion; anda panel cooperating with said body to close off said interior space, said panel being constructed and arranged to deflect in response to a pressure difference across said panel so as to increase said contact force.