|Publication number||USRE28797 E|
|Application number||US 05/600,413|
|Publication date||May 4, 1976|
|Filing date||Jul 30, 1975|
|Priority date||Jul 22, 1969|
|Publication number||05600413, 600413, US RE28797 E, US RE28797E, US-E-RE28797, USRE28797 E, USRE28797E|
|Inventors||Clarence T. Brewer|
|Original Assignee||Solo Cup Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (28), Classifications (16)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This invention relates to lids for cuplike containers and more particularly to lids of the single end use, disposable type for cuplike containers having a curled top edge or bead.
Cuplike containers, having their top edges curled outwardly, downwardly and back under to form curled rims or beads, are commonly used to package foods, both solid and liquid, especially for carryout and end-point serving. Such containers are generally of the tapered or conical nesting type. The containers may be manufactured from sheet paper, treated or saturated with wax or a combination of wax and plastic, or from sheet paper laminated to thin plastic which serves as the interior of the container. Alternately, the cuplike containers may be post-treated with a coating, or a saturated coating, of wax or of a combination of wax and plastic. Containers of the above-described type may also be manufactured from sheet plastic by the thermovacuum-pressure forming process. In both the paper and plastic manufacturing processes, it is common practice to form the body of the container in one operation and the head in another operation, with both operations being automatically and progressively performed in one machine.
Variations in material characteristics, in sheet thickness and in manufacturing tools and processes cause dimensional tolerances in the container mouth diameter and the size or thickness of the bead that are difficult to economically control below a certain minimum. There are roundness irregularities in the circumference of the container and there are also variations in the uniformity of the bead size around the top edge of the container. Also, the bead is not exactly round; it is normally either round or egg-shaped with the top edge having the smaller curvature. The bead in containers made of sheet paper has a slightly enlarged portion resulting from the side seam of such containers.
The lid for such a container, in order to fit snugly on the container and be reasonably leaktight, should compensate for these nonuniformities or irregularities in the bead and container mouth and the variations between containers. Of course, the lid should be easy to apply to, or remove from the container. Other desirable features which should be provided in the lid are: (1) The lid should have sufficient retention on the container so that when two or more full containers with attached lids are placed in a bag or package in juxtaposition with the edge of the lid of one container overhanging one or more other lids, the weight of that one container does not peel or rake off the lid; (2) When the container with the attached lid is held or lifted by gripping opposite sides of the skirt of the lid with the thumb and fingers, the retention of the lid on the container should be increased; (3) The skirt of the lid should be of sufficient length to provide sanitary protection for the lip area when lifting or holding the container with the attached lid in the above-described manner; ( 4) For ease of manufacture, the lid should be of such a design that it is easy to form by a thermovacuum-pressure forming process and is easy to strip from the mold.
Stacking of the lid is another important consideration, particularly where the lids are picked up, conveyed or transported to packaging for shipment or where the lids are dispensed to end use. The lids should nest freely, one with the other, and should nest uniformly laterally so as to form a very rigid column that can be compressively picked up or conveyed by the ends of the stack. The lids should maintain this uniform stack in a shipping carton and be capable of separation from nesting without resistance for dispensing to end use.
An object of the present invention is to provide a lid which incorporates one or more of the above desirable features.
Other objects and advantages of the invention will become apparent from the detailed description taken in connection with the accompanying drawings in which:
FIG. 1 is a perspective view of a container having an attached lid embodying the features of the invention;
FIG. 2 is a top view of the lid of FIG. 1;
FIG. 3 is an enlarged fragmentary, cross-sectional view of a lid on a container;
FIG. 4 is an enlarged fragmentary, cross-sectional view of several lids in a stack; and
FIG. 5 is an enlarged fragmentary view of flutes and lands on the lid.
As shown in the drawings, a lid 11 is provided having a circumferentially extending cavity 12 (as best seen in FIG. 3) for releasable sealing engagement with a bead 13 of a cuplike container 15 which may be either made by vacuum forming sheet plastic or made from sheet paper, as previously described. The lid 11 is formed with a central disclike panel 17 adapted to extend substantially across the open mount 19 of the container when the lid is telescoped on the container. The lid also includes a conical lid skirt 21 which extends downward from the lower edge of the cavity 12. The lower portion of the cavity 12 and the upper portion of the skirt 21 form a waist and this waist is interrupted by a series of circumferentially spaced flutes 22. In telescoping the lid 11 on the container 15, the portions 23 of the skirt between the flutes 22 act as lands 23 which are cammed laterally outward by the bead 13 of the container thereby expanding the waist to permit it to pass over the container bead 13. A corrugated ring 25 is disposed between the cavity 12 and the central panel 17, for a purpose described hereinafter. The lid 11 is provided with stacking lugs 27 projecting downwardly from the central panel to rest on the top of the central panel of a lid immediately beneath it, as best seen in FIG. 4.
Referring now in greater detail to the embodiment shwon in the drawings, the lid 11 is preferably designed so that it is easily manufactured from a plastic sheet by a thermovacuum-pressure forming process and is easily stripped from its mold. For purposes of description, the lid 11 is described as it would be viewed from the container or its underside. The lid 11 includes the conical skirt 21 which, as illustrated, flares generally downward and outward from the lower portion of the cavity 12 to a maximum diameter at its lower free edge. Along the lower edge of the skirt 21 is an outward extending and substantially horizontal flange 29 which may be employed as a surface to be pushed for detaching the lid 11 from the container 15. This flange, which is necessary for presently available trimming operations, should be as narrow as possible to minimize the possibility of the lid being raked off by adjacent containers, as previously described.
When the lid 11 is initially placed on the container, it is normally skewed with one side of the bead 13 seated fully in the cavity 12. The inner diameter of the lower free edge of the skirt 21 is made of sufficient diameter to cover the maximum tolerance outside diameter of the container bead 13 when the lid 11 is in the skewed position on the container. The skirt 21 is made of sufficient length to provide a low-pressure angle as the skirt slides over the bead 13. When the lid 11 is attached to the container 15, the skirt 21 provides sanitary protection for the lip area about the container mouth.
The upper portion of the skirt 21 and the lower portion of the cavity 12 form a waist. The waist is interrupted by a series of circumferentially spaced-apart flutes 22. The illustrated flutes 22 are radius grooves which is the preferred shape but, in certain applications, they also may be narrow slots. These flutes 22 provide telescopic rigidity to the skirt 21 and the lower portion of the cavity 12, thereby avoiding an inward bellows action when the lid is applied to the container.
The relatively flat portions 23 of the skirt 21 between the flutes act as lands, which are cammed outwardly by the bead 13, when the lid is pressed downwardly on the container 15, without digging in or marring the bead. To this end the lands 23 have sufficient conical strength structurally to cause the flutes to expand circumferentially or diametrically, that is, the width of the lands 23 vary between the lower and upper portions thereof. Each land 23 has a wider circumferentially extending lower portion 37 (FIG. 4) at the lower free end of the skirt 21 than at an upper or innermost portion 39.
The lands 23 are connected to lower rounded portions 43 of the rim-receiving cavity 12. The lower rounded portions 43 of the cavity 12 form hooks or latches that snap over the bead 13 and apply a slight tightening down camming action to hold the lid against inadvertent separation from the container 15. The lower rounded portions 43 extend inward approximately to one-half the width of the cavity 12. For the purpose of facilitating the camming and snapping action of the hooks 43 on the container bead 13, the lower rounded portions 43 are formed with a downwardly curved surface disposed at an angle of about 43° to the horizontal as exemplified by the angle A in FIG. 4. With a smaller angle it would be difficult to remove the lid from the mold.
The waist is expanded by the narrower upper portions 39 of the lands 23 being cammed laterally outwardly. This camming action causes the walls forming the adjacent flutes 22 to be distorted and the rounded portions 43 to roll outward. The increased intermediate widths of the flutes 22 and the nonparallelism of the land-defining walls also aid in the flexing to accommodate the bead 13. The camming action is facilitated by providing the land 23 at a small angle relative to the vertical (angle B in FIG. 3) preferably at an angle not greater than about 31°.
The pivoting of the land 23 and the outward rolling of the rounded portions 43 to expand the waist are further enhanced by having the tops of the flutes 22 joined to the rim-receiving cavity 12 as close as possible to a point of tangency with the inner surface of the cavity 12, as best seen in FIG. 3. If the tops of the flutes 22 were made tangential to the cavity 12, the flutes 22 would extend further upwardly to the center of the cavity 12 and thereby provide passageways between the rim and cavity wall through which liquid might leak. The preferred angle for the point of connection of the flutes 22 to the cavity 12 is at an angle of about 15°-20° from a horizontal plane, as illustrated by the angle C in FIG. 3.
As previously explained, beads 13 are formed by a rolling of the material which results in noncircular cross sections and sometimes results in flats, bulges or other variable cross-sectional dimensions in the beads. In seamed containers, the double thickness of the material at the seam causes an enlargement or bulge. It has been found that containers may have a tolerance in the height of the bead of 0.025 inches. To seal with beads 13 having such variations, the cavity 12 is formed with a vertical dimension, i.e., a height, to receive the maximum tolerance dimension of a container bead. Additionally, an upper rounded wall 45 (FIG. 3) of the cavity 12 is blended into a flat vertically disposed outer wall 49 with the result that the cavity 12 is elongated in the vertical direction. The inner diameter of the vertical wall 49 is selected to be slightly less than the minimum tolerance diameter of the bead 13 or that of the minimum tolerance diameter of the bead with interference. The flatness of the cavity 12 provided by the vertical wall permits the cavity to bulge where needed.
The upper arcuate wall 45 is joined at its inner end with an upwardly facing curved surface 53 at the lower edge of the corrugated ring 25. The corrugated ring 25 extends inward and upward from its lower edge and includes a plurality of corrugations 57 each of which has a substantially uniform circumferential extent and decreases in height. The sides of the corrugations 57 are radially disposed, the corrugations thereby being wider at the outer ends than the inner ends.
The corrugated ring allows the upper wall 45 of the cavity to roll upwardly and outwardly to accommodate variations in the bead diameter. Also, the upwardly curved surface 53 readily deforms in a localized area as the corrugated ring 25 spreads circumferentially and flexes upwardly whereby the lid may fully seat and grip despite bulges or other such enlargements. The corrugated ring 25 also allows the lid to be easily removed from the container without any abrupt or jarring action by placing two or more fingers on top of the lid, near the edge of the panel 17, and the thumb under the lower edge of the skirt 21 and gently squeezing between the thumb and fingers simultaneously with a prying action.
The corrugated ring 25 is connected to the center panel 17 by means of a conical-shaped collar or tapered cylinder 55. The angle between the face of the center panel 17 and the collar (angle D in FIG. 3) is made greater than 90° and the angle between the collar 55 and the upper surface of the corrugated ring 25 (angle E in FIG. 3) is made approximately 90° so that the lid does not permanently buckle. Alternately, the angles may be interchanged (i.e., angle D may be made 90° and angle E may be made greater than 90°. Also, this collar 55 facilitates the rolling of the cavity 12.
The preferred manner of stacking is by means of three spaced stacking lugs 27, each in the shape of an oblique frustum of a triangular pyramid with the edges of faces flattened or rounded. The lugs are integrally formed in and project downwardly from the top panel 17 to a position in horizontal plane beneath the plane of lower portions 43 of the cavity 21. More particularly, the bottom walls 61 on the stacking lugs 27 abut the central panel 17 of a lid immediately below to space the skirt 21 from engaging and prevent its moving into a wedging engagement with the outer surface of the lid cavity 12. As illustrated in FIG. 2, the stacking lugs are each positioned so that one corner 67 thereof is directed outwardly so that, when the plastic material from which the lid is thermoformed shrinks upon cooling, the lid is easily stripped from the mold.
The preferred equipment for forming a series of lids simultaneously from a sheet of plastic has the stacking lugs angularly spaced at different angles in the various lid forming dies so that the lids when formed have the stacking lugs in a series of nonmatchable positions. Thus, each group of lids formed from a single sheet may be stacked immediately without having the bottom walls 61 of one lid aligned and projecting into the openings of the stacking lugs in the lid next below.
From the foregoing, it will be seen that the lid may be manufactured by thermoforming or pressured formed from a sheet of plastic and provided with sufficient flexibility at the depending skirt to fit containers having bead diameters which vary substantially over a relatively wide range of tolerances. The lids are particularly suited for accommodating bulges at the seams or other nonuniform cross sections in roller beads. The lids may be readily stacked yet are prevented from wedging into engagement with one another which would prevent the easy release of one lid from another.
While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure but, rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.
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|U.S. Classification||220/781, 206/508, 220/784|
|Cooperative Classification||B65D2543/00537, B65D2543/00296, B65D43/0212, B65D2543/00731, B65D2543/00555, B65D2543/00796, B65D2543/00685, B65D2543/00638, B65D2543/00092, B65D2543/00509, B65D2543/00027|