The present invention relates to container closures or caps of the pry-off type to a method of making the same and to containers, a principal object of the invention being to provide a closure and container in combination wherein the closure may be more easily removed and may be reapplied without loss or with less loss in original sealing efficiency than in other existing closures of the pry-off type, the cap being adapted to maintain a vacuum and to resist internal pressures.
This application is a continuation-in-part of my application Serial No. 746,457, filed October 1, 1934.
In carrying out the invention, I utilize a resilient skirted metal cap having locking lugs preferably preformed in the skirt, the cap being adapted to snap-on the container finish in initial application. It is, in fact, a major feature of the invention that the cap may be provided in original manufacture with the locking lugs so that no special lug forming machinery is required when the cap is to be applied. I preferably utilize a container of glass, or like material, and preferably with a special finish particularly designed for efficient cooperation with the cap.
The skirt of the cap is initially of generally cylindrical form. Its free edge is strengthened by rolling to form a wire edge and is thus inexpansible and resistant to any tendency to distort it from its original circularity. The lugs are preferably formed in the skirt just above the wire edge and have ordinarily a restricted axial dimension and a major circumferential dimension. Preferably, also, the skirt is provided with radially extending flutings or corrugations which in a preferred form of the invention extend substantially down to the wire edge so that the lugs are struck in the zone of the lower ends of the flutings.
In providing the lugs in the zone of the flutings, I have adopted a novel method of manufacture whereby the lugs are hardened and thus rendered less liable to deformation. According to the new method, I first provide a blank or shell having a top and a substantially cylindrical skirt portion with a bottom flange. The skirt of the cap is then corrugated and the flange turned to provide a wire edge. The lugs are now struck from the corrugated skirt at relatively widely spaced points around the same and at these points the corrugations are substantially obliterated. This working of the metal of the lugs appreciably hardens the same.
In the closure and container combination herein contemplated, the container has a top rigid bead preferably of the specific form to be hereinafter described and there is a definite relation between the inside diameter of the cap and the bead diameter in that the former is always substantially greater than the latter. With the cap and bead of normal dimensions, the skirt portions of the cap between the lugs are enabled to flex radially inwardly as the lugs ride over the bead so that the skirt portions at the lugs may be flexed outwardly to prevent lug deformation. A normal relation of the cap and bead may be taken to be that in which the skirt portions between the lugs flex inwardly into substantial contact with the bead at the same time that the lugs reach the maximum circle of the bead as they ride over the latter.
It is of coure impossible to secure absolute uniformity in the finish of glass containers and the bead diameter, for example, varies appreciably in different lots made to the same specifications. Furthermore, caps made to the same specifications may vary somewhat in dimensions due to various factors, such, for example, as variations in the metal. An important advantage of the present invention is that such variations are effectively accommodated so that the proper seal is secured whether the dimensions are normal so as to provide the contemplated clearance between the skirt and bead or whether, through deviation in the cap or container finish or both, the clearance is greater or less than normal. In the case of less than nornial clearance, the cap skirt between the lugs will come against: the-head before the lugs have reached the maximum circle of'-he bead. Under these circumstances, the lugs are permanently somewhat outwardly displaced' as they pass the maximum circle of the bead but the cap may be removed and reapplied with no appreciable, if any, further distortive effect, so that in re-use substantially original sealing effect is obtained. In the case of greater than normal clearance, there is of course no permanent distortive effect on the cap and although the lugs will not project under the shoulder to the same extent as under normal conditions, their locking effect is entirely adequate.
In the heat processing of goods in sealed containers it is necessary that relief be provided for high internal pressures. The cap and container combination of the preSent invention lend themselves readily to this finctionr when a top sealing gasket of low resiliency is used. Under the force of high internal pressure the? cap ;may rise "relatively to the containeri sufficiently to permit venting past the gasket when the latter is of such nature as not to expand to the full extent of the lift of the cap.
While, as stated at the outset, in carrying out the invention I ordinarily utilize a container of glass or like material, the preferred bead finish may be applied to a sheet metal container.
The special container finish to be described hereinafter is designed to cooperate to the most efficient degree with the cap so as to obtain maximum sealing efficiency and ease of manipulation.
In order that the invention may be clearly understood, I shall proceed to describe it in detail with reference to the illustrative embodiments shown in the accompanying drawings, in which: Figure 1 is an elevation of the top portion of a container with a closure applied thereto in accordance with the present invention; Figure 2 is a bottom plan view of the cap of Figure 1; Figure 3 is an enlarged view showing the container of Figure 1 in elevation and the cap in section and with the latter in position for application; Figure 4 is a fragmentary view in axial section, and still further enlarged, of the container and cap of Figure 1; Figure 5 is a partial section through the skirt of the cap substantially on line 5-5 of Figure 4, the embraced portion of the container being shown in plan; Figure 6 is a fragmentary axial sectional view of a cap and container wherein less than normal clearance between the container bead and cap skirt is afforded; Figure 7 is a view similar to that of Figure 6 with the cap applied; Figure 8 is a composite view, further enlarged, of that portion of the cap shown in Figures 6 and 7; Figure 9 is a view similar to that of Figure 6 but illustrating more than normal clearance between the container bead and the cap skirt; Figure 10 is a view similar to that of Figure 9 but showing the cap applied; Figure 11 is a view similar to that of Figure 9 but showing a different gasket arrangement; Figure 12 is a view similar to that of Figure 11 but showing the cap applied; Figure 13 shows an elevation of the original cap blank in preferred form; Figure 14 shows the blank of Figure 13 subsequent to a skirt knurling and edge rolling operation; Figure 15 shows the shell of Figure 14 with the lugs applied thereto; Figure 16 is a side elevation of a blank after an edge rolling and knurling operation in which the knurls or corrugations are confined to a circumferential zone spaced upwardly from the wire edge; Figure 17 shows the shell of Figure 16 with the lugs formed therein in the smooth skirt portion below the corrugations; Figure 18 is an elevation of a cap in which the skirt corrugations are entirely omitted; Figure 19 is an axial section of a cap and the upper portion of a container illustrating the venting action when a gasket of low resilience or elasticity is used, and Figure 20 is a similar section of a cap in com'bination with a sheet metal container.
In Figures 1 and 2 of the drawings, I have reproduced a cap and Jar of a standard size, the 76 cap being sixty-three millimeters in diameter and both it and the container being assumed to be normally proportioned or at least of such relative dimensions as to provide no less than normal clearance. Figures 3 to 5 are merely enlargements based on the typical showing of Figures 1 and 2.
Referring to Figures 1 to 5, reference numeral 20 indicates generally a sheet metal cap and reference numeral 21 a glass container here shown as a jar. The cap has a circular top 22 and an initially generally cylindrical depending skirt 23, the edge of the latter being curled outwardly to provide a lower wire edge 24 and being knurled thereabove to provide axially extending corrugations or flutings 25. The flutings extend from substantially the cap top to the wire edge and are formed continuously circumferentially of the skirt. In the typical cap shown, the skirt has a depth of about five-eighths of an inch and above its lower reinforced edge and preferably in the zone of the lower ends of the flutings, as here shown, is provided with a series of impressed lugs 26. The lugs are reinforced by the flutings at the sides and thereabove.
With a cap of the size shown in Figures 1 and 2, I preferably provide six lugs 26 in equally spaced relation. The distance between opposite lugs is usually from 2.437 to 2.442 inches, the circumferential extent of each lug being about onefourth of an inch and the axial extent about one-sixteenth of an inch. The inner extremities of the lugs are on a radius of about one-thirtysecond of an inch and the top surfaces of the lugs are inclined at about a thirty degree angle.
The lugs are substantially V-shaped in cross section axially of the cap, as shown in Figure 3.
The above dimensions, it will be understood, are merely typical for a cap of the size contemplated in Figures 1 and 2. In the case of a smaller cap, as few as three lugs may be used and more than six lugs may be provided in the case of larger caps. Different effects may also be secured through variation in the circumferential extent of the lugs. I preferably use the minimum number of lugs consistent with a properly distributed and rigid gripping action in order that the arcuate skirt portions between the lugs may be of large circumferential extent.
To complete the cap, a gasket 27, preferably of rubber and of the shape shown, is affixed to the underside of the top wall 22, the top wall, as here shown, being provided above the gasket with an annular rib 28.
The preferred steps in the manufacture of the cap just described are illustrated in Figures 13 to 15. In the first step a hat-shaped blank 29 is first struck from suitable sheet metal, the blank comprising a top wall, a cylindrical skirt and an outwardly directed annular flange at the lower edge of the skirt. In this initial operation, the annular rib as at 28, Figure 3, is also formed.
In the next operation, the skirt portion of the shell is knurled to provide the corrugations or flutings and the lower flange is rolled to form a wire edge, all as appears in Figure 14, the still incomplete cap being therein designated at 30.
The completed cap 20 is shown in Figure 15, the lugs 26 having been pressed in the skirt in a final operation. Each lug, as here shown, is of considerably less axial extent than the flutings and each has a circumferential extent equal to that of several of the flutings. The lugs being formed in the zone of the flutings by indenting the latter inwardly, the latter are substantially obliterated in the lugs so that the inner edges of the latter are substantially smooth as shown in Figure 2. The working of the lug metal by first forming corrugations therein and then ironing them out in the impressing operation has an appreciable hardening effect so that the lugs have increased resistance to deformation. The lugs are further appreciably reinforced by the flutings at the sides thereof and particularly the unmutilated portions of those immediately above the lugs and lighter metal may be used than when the knurling is omitted. For the reasons mentioned, the preferred form of cap and preferred method of manufacture are those which have just been described.
The wire edge 24 of the cap Is substantially non-expansible and tends to maintain the original circularity of the skirt as a whole. The lugs are accordingly preferably positioned not far above this restraining element, although, if increased yieldability of the skirt is desired, the lugs may be positioned further away from the wire edge. If the lugs are positioned, for example, substantially midway between the wire edge and the top of the cap, the controlling effect of the wire edge would be somewhat lessened and a certain expanding and contracting effect in the flutings upon application and removal of the cap may be encountered.
In Figure 16, I have shown a shell 31. formed from a hat-shaped blank as in Figure 13 but having the lower ends of the flutings terminating substantially above the wire edge to provide a smooth zone 32 in which the lugs 33, Figure 17, are formed.
The cap 34, Figure 18, is formed from a blank the same as is shown in Figure 13, but the knurling is entirely omitted.
While the caps shown in Figures 17 and 18 may be successfully used, I prefer the cap as shown, for example, in Figure 15, for the reasons already given.
The container 21 has a mouth surrounded by a rigid circumferentially continuous bead 35 which has a continuous circumferential lower shoulder 36 flared upwardly and outwardly at about a thirty degree angle, this being also the angle of the top faces of the lugs,- as above mentioned.
From its circle of maximum diameter, the bead is sharply rounded upwardly and downwardly on about a one-thirty-second of an inch radius and is converged upwardly and inwardly to provide a substantially conical upper, outer surface 37 which is inclined at about a forty-five degree angle. The lip has a crest 38 which provides a sharply curved top sealing surface. The crest is Sstruck on about a one-thirty-second of an inch radius and forming the upper edge of the bead, the crest being rounded off to the inner container surface. Beneath the bead 35, the container is provided with a pry-off ledge 39, this being spaced Ssomewhat below the wire edge 24 when the cap is applied, as shown in Figures 1 and 4, so that a coin or other appropriate instrument 40 may be inserted.
With the cap in position on the container finish as shown in Figure 3, rib 28 lies immedi6ately above the crest 38. Upon application of downward pressure, the lugs 26 are cammed radially outwardly by the surface 37. Outward movement of the lugs is accommodated by the skirt portions at the lugs, these latter moving radially outwardly as enabled by the radially inward movement of the intermediate skirt portions. As the lugs come to the circle of maximum diameter of the bead, the skirt in the plane of the lugs may , be conceived of as assuming a substantially hexagonal shape with the lue disposed in the angles and the sides of the fiure substantially tangential to the bead. Actually, of course, the skirt portions between the lugs do not entirely straighten out, the hexagonal configuration Just mentioned being an exaggeration of the actual condition of the skirt used merely by way of Illustration.
When the lugs have passed beneath the inwardly and downwardly inclined under surface of the shoulder, their top surfaces coact with the latter to hold the cap in sealing position, being drawn under the shoulder as the skirt portions at the lugs flex inwardly and those between the lugs flex outwardly, due to the inherent resiliency of the skirt metal, so that the circularity of the skirt in the plane of the lugs is substantially resumed. F1gure 5 is a greatly enlarged view illustrating the action of the skirt between two lugs 26 upon application or removal of the cap.
The full lines show the skirt between the lugs as inwardly flexed upon application or removal of the cap, the dotted lines showing the original position of the skirt as well as the position which it resumes when the lugs have passed under the shoulder. With the cap applied, gasket 27 is compressed between the top of ..e cap and the top edge of the bead so that when the capping pressure is removed the reaogtn of the gasket pulls the lugs against the beadi, lculder. The upper edge or crest 38 of the bead provides a thin lip which gives a localized linr or band of contact with the gasket so as to embed itself readily in the latter without as great , resistance of the latter as would be experiencedin the case of a sealing edge of greater area. 'te gasket is highly compressed in a narrow annutr zone, particularly in conjunction with the rib 28 which immediately overlies the crest 38.
The relationship of the skirt and container diameters permits the lugs to ride upon the inclined shoulder without releasing the cap while maintaining constant tension of the skirt to afford a seal between the gasket and the top surface under varying container finish tolerances. In view of the inward spacing of the sealing edge or crest 38 from the maximum circle of the bead, the pressure-affected area of the cap, as applied to a pressure container, is substantially reduced. Furthermore, the cap has a considerable substantially free outward overhang as at 22', Figure 4, being of substantially greater diameter than the sealing surface of the container, and the sealing contact is disposed in axially extending lines spaced inwardly from the lugs and the container shoulder. This overhang is springy and thus accommodates any irregularities in the finish so that uniform sealing effect with lack of local strains is secured and the adaptability of the cap as a whole is enhanced. The overhang and the springy skirt tension contribute to maintain a seal under varying container finish tolerances, and function as an infinite number of C clamps.
While the expansive forces of the gasket 27 g6 itself are along line A, Figure 4, its reaction is transmitted to the lugs on lines as at B, Figure 4, which lines are substantially normal to the shoulder surface 36 so that a substantially right angle pull is exerted on the lugs. The angle to the outside of line B as here shown is in fact somewhat greater than a right angle so that the gripping effect of the lugs is all the more favorable. The resultant force due to skirt tension is on a line C which is at the angle of the shoulL? der surface 30 and the force exerted by the opening implement 40 is more or less along this line and is thus most effectively applied. The pry-off force, of course, has an upward component so that the cap is tended to be lifted as well as flexed outwardly but the major component is outward.
The caps will ordinarily be applied manually to the jars in the position shown in Figure 3 for subsequent subjection to capping pressure. As shown in Figure 3, the bead surface 37 supports the lugs 26 and centers the cap. If sealing is to be effected under vacuum, air readily escapes from the Interior of the containers through the spaces between the lugs.
In Figures 9 and 10, the cap and finish are shown in a somewhat abnormal relation wherein more than normal clearance is afforded, the net effect being substantially the same as that shown in Figure 4, although, as will be noted, the lug 26, Figure 10, is engaged under the bead shoulder to a lesser extent than in Figure 4. Adequate sealing effect is nevertheless secured, although the tension effect of the gasket is somewhat less. In the cap as shown in Figure 9, the side of the skirt 23 is parallel to the container axis. In Figure 10, however, it will be noted that the side of. the skirt is slightly downwardly flared immediately above the lug, this being caused by the outward component acting on the lug. The same slight flare appears in Figure 4.
According to Figures 6 and 7, the diameters of the cap skirt and container bead are so related that less than normal clearance is provided between the two. Under these circumstances, the inward flexing of the skirt portions between the lugs is not of sufficient range to permit the skirt portions at the Jugs to flex outwardly to the required extent. This being the case, as the lugs pass the maximum circle of the bead, they are in effect moved outwardly about axes substantially as at x, Figure 7, and bulges as at y are consequently formed above the lugs. In this operation the shape of the lugs themselves has not been changed, but only their position, with the consequent formation of the bulges as at y and the slight flare which has previously been discussed. The bulges as at y are formed during the initial application of the cap and no further permanent deformation of the skirt is caused as the result of removal or reapplication of the cap.
For comparative purposes, I have shown in Figure 8, on a greatly enlarged scale, a portion of the cap skirt, Figures 6 and 7, before and after application. 'he full lines show the skirt before application, while the dotted lines show the skirt after initial application and also as it would appear upon removal of the cap from the bead.
In Figure 7 it will be noted that the gasket is considerably compressed.
The slight deformation just described and resulting when the clearance is less than normal is entirely unobjectionable from a practical standpoint and the same efficient seal is secured as when the relation of the parts is the planned normal. Experiments with the cap and bead variously related have shown that a perfect seal is maintained at least up to internal pressure of twelve pounds per square inch.
If it is desired to isolate the gasket from the container contents, a side sealing gasket as at 41 may be used. The gasket 41 is of substantially rectangular cross section in its initial form as shown in Figure 11, its outer surface being close to or in contact with the inner surface of the skirt and its inner surface being outside the crest 38 of the bead. A compressible sealing and protective disc 42, which may be of felted or other suitable substance, is interposed between the gasket and the top of the cap, as here shown. When the cap is applied the gasket is compressed to the form shown in Figure 12 and the marginal portion of the sealing disc is somewhat compressed between the crest of the bead and the rib 28 so that the gasket is sealed from the contents of the container. Disc or gasket 42 provides a primary seal and gasket 41 a secondary seal.
Regardless of the type of gasket used, although that first described is considered by me to be preferable, I prefer to use in the cap and container combination the novel container finish shown and described. With this finish the bead conformation in all cases facilitates quick removal of the cap, inasmuch as the latter is free as soon as its lugs have passed above the relatively sharp, and hence restricted, bead flange.
The engaging surface of the lugs and bead are complementarily inclined at such an angle as to provide adequate lock, while at the same time permitting ready removal, and the conical surface 37 is designed to exert an efficient camming action on the lugs upon cap application.
The inward spacing of the sealing edge or lip of the container affords also the numerous advantages discussed with particular reference to Figure 4. I also prefer to use a cap in which the lugs are formed in original manufacture but the lugs may be impressed during the capping operation. In the latter case the advantages of efficient re-usability are still retained.
Many types of packaged products require to be heat processed after packaging. In the processing operation, high internal pressure is developed in the package and the excess must be permitted, to escape. The cap and container combination of the present invention lends itself readily to the accomplishment of the proper venting action when a top sealing gasket is used and when the same is of comparatively low resilience or elasticity.
I have illustrated this venting or valving action in Figure 19 wherein the same cap 20 and container 21 as heretofore described are contemplated, the gasket 27a, however, having comparatively low resilience, so that while it has a measure of rebound or expansion after compression, this action is slow or incomplete and when the cap top is lifted relative to the container upon the occurrence of high internal pressure, venting can occur past the gasket as indicated by the arrows in Figure 19. From this figure, it will be seen that the annular depression caused by the lip of the container is to a great extent retained upon release of the gasket from 6s the compressive action of the cap, venting, as here shown, occurring between the container lip and the gasket. The possible expansion of the gasket is less than the permissible extent of movement of the cap top relative to the container lip.
Upon the development of high pressure within the container, the cap is slightly lifted, the lugs 26 riding upwardly and outwardly on the upwardly and outwardly flared lower shoulder 36 of the bead. As the skirt is expanded at the lugs, it flexes inwardly intermediate the lugs in the manner above discussed. Upon the completion of the venting action, the skirt tension at once acts to cam the lugs 26 inwardly and downwardly on surface 36 so that the sealing relation of the gasket is immediately resumed without any influx of the external atmosphere.
The valving action is strictly one-way. It is facilitated by the narrow pressure area between the gasket and container lip and by the fact that this area is inwardly removed a substantial distance from the cap skirt so that any bulging tendency of the cap top is effective to assist in providing venting clearance. In Figure 19 the cap top is shown as being slightly upwardly bulged.
The material of gasket 27a may be of the general composition described in the patent to Parker No. 1,899,821, suitably modified to render the gasket more plastic or less resilient. For example, reduction of the sulphur in the Parker formulae will result in decreased resiliency as the compound will not vulcanize to its greatest degree of elasticity. Talc has a similar result when substituted for clay in the Parker formulae and if reclaim instead of crepe rubber is used, the resiliency will be reduced. To the same end, an increase in the amount of lubricant used will be effective. By way of example, the following is a suitable formula:Rubber ----------------------pounds_Accelerator -------------------ouncesAnti-oxidant ----------------- pound-SStearic acid------.----.-------. . do Sulphur ------------------ - do---Zinc oxide ------------------- do-Talc --------------------------do -Ceresin wax-----------------do 35 Lampblack (color) ..------..-. __ grams-_ Comparing the above with the Parker formulae, note the substitution of talc for clay, an increased amount of wax, and use of less rubber. 40 If reclaim is used in place of some of the crepe, the rubber constituent would increase somewhat over 27 pounds since the reclaim contains only about 60 per cent rubber.
As a matter of comparison, assuming the elas45 ticity of the ordinary rubber ring to be approximately 75 per cent, that of the gasket 27a would be about 25 per cent. It will be understood that with a rubber ring of ordinary elasticity, the hermetic seal of the package of the present in50 vention would be retained since the gasket would expand sufficiently to maintain a constant seal between the cap and the container lip in the presence of such an unusual internal pressure as would displace the cap. Such a pressure would, 55 of course, be encountered only accidentally outside of a heat processing operation, and in such latter operation the gasket of low resiliency would be used.
While, in the practice of the invention, the con60 tainer will ordinarily be of glass or similar substance, the invention is not limited in this respect and in Figure 20 I have shown a cap 20 as applied to a sheet metal container 50. As here shown, the container 50 comprises a cylindrical 65 body 51, which it is understood, is permanently closed at its lower end, having crimped to its upper edge a neck 52. The latter has a cylindrical portion immediately above the body 51 and reduced in diameter as compared to the 70 latter. Above this reduced cylindrical portion, the neck is flared upwardly and outwardly to provide a conical shoulder 53 above which the neck is tapered upwardly and inwardly to provide a top outer conical surface 54. At the top of surface 54, 75 the neck metal is turned sharply inwardly to provide a flange 55 between which and surface 54 is a relatively sharp, lip 56. The gasket is assumed to be the same as gasket 27a discussed with reference to Figure 19, although a gasket 21 of full resiliency may, of course, be used, the choice depending on the particular requirements. It will be noted that the bead shoulder 53 is somewhat steeper than the shoulder 36, Figure 19, and is also somewhat wider. This form of lug shoulder is sometimes preferable when the venting characteristic is to be made use of, permitting, as it does, relatively greater and easier upward movement of the cap relative to the container. Such a shoulder may of course be applied to the glass finish if desired. It will be evident that variations in details and arrangement may be made without departure from the invention as defined in the following claims.
I claim: 1. In combination, a container having a mouth surrounded by a rigid bead presenting an inwardly and downwardly inclined undersurface forming a continuous circumferential shoulder, said container having a sharply curved top sealing surface disposed inwardly from and above said circumferential shoulder, a metal snap-on and pry-off cap adapted to maintain a vacuum and resist internal pressures comprising a top of substantially greater diameter than said sealing surface and, depending therefrom, an initially cylindrical skirt having a lower wire edge and relatively widely spaced lugs having top surfaces above said edge, a gasket between the container top and cap top and making a sealing contact disposed in axially extending lines spaced inwardly from the lugs and container shoulder whereby to provide an overhang of the top and a springy skirttension contributing to maintain a seal under varying container finish tolerances, said skirt having an inner diameter greater than the diameter of the bead and the normal relationship of such diameters being such that the lugs upon initial application of the cap may be snapped over said bead with the skirt portions between the lugs temporarily flexing inwardly to enable the skirt portions at the lugs to flex temporarily outwardly sufficiently to prevent deformation of the lugs and said relationship of the skirt and container diameters permitting said lugs to ride upon said inclined shoulder without releasing the cap while maintaining constant tension of the skirt to afford a seal between the gasket and top surface under varying container finish tolerances.
2. In combination, a container having a mouth surrounded by a rigid bead presenting an inwardly and downwardly inclined undersurface forming a continuous circumferential shoulder, said container having a sharply curved top sealing surface disposed inwardly from and above said circumferential shoulder, a metal snap-on and pry-off cap adapted to. maintain a vacuum and resist internal pressures comprising a top of substantially greater diameter than said sealing surface and, depending therefrom, an initially cylindrical skirt having a lower wire edge and relatively widely spaced lugs above said edge, each lug being disposed closely adjacent the wire edge and being substantially V-shaped in cross section axially of the cap whereby to provide a sliding wedging engagement with said shoulder and an instantaneous snap-on and snap-off engagement with the shoulder, a gasket between the container top and cap top and making a sealing contact disposed in axially extending lines spaced inwardly from the lugs and container shoulder whereby to provide an overhang of the top and a springy skirt tension contributing to maintain a seal under varying container finish tolerances, said skirt having an inner diameter greater than the diameter of the bead and the normal relationship of such diameters being such that the lugs upon initial application of the cap may be snapped over said bead with the skirt portions between the lugs temporarily flexing inwardly to enable the skirt portions at the lugs to flex temporarily outwardly sufficiently to prevent deformation of the lugs and said relationship of the skirt and container diameters permitting said lugs to ride upon said inclined shoulder without releasing the cap while maintaining constant tension of the skirt to afford a seal between the gasket and top surface under varying container finish tolerances.
3. In combination, a container having a mouth surrounded by a rigid bead presenting an inwardly and downwardly inclined undersurface forming a continuous circumferential shoulder, said container having a sharply curved top sealing surface disposed inwardly from and above said circumferential shoulder, a metal snap-on and pry-off cap adapted to maintain a vacuum and resist internal pressures comprising a top of substantially greater diameter than said sealing surface and, depending therefrom, an initially cylindrical skirt having a lower wire edge and relatively widely spaced lugs above said edge, each lug being disposed closely adjacent the wire edge and being substantially V-shaped in cross section axially of the cap whereby to provide a sliding wedging engagement with said shoulder and an instantaneous snap-on and snap-off engagement with the shoulder, each lug having a substantially greater extent circumferentially than axially of the cap, a gasket between the container top and cap top and making a sealing contact disposed in axially extending lines spaced inwardly from the lugs and container shoulder whereby to provide an overhang of the top and a springy skirt tension contributing to maintain a seal under varying container finish tolerances, said skirt having an inner diameter greater than the diameter of the bead and the normal relationship of such diameters being such that the lugs upon initial application of the cap may be snapped over said bead with the skirt portions between the lugs temporarily flexing inwardly to enable the skirt portions at the lugs to flex temporarily outwardly sufficiently to prevent deformation of the lugs and said relationship of the skirt and container diameters permitting said lugs to ride upon said inclined shoulder without releasing the cap while maintaining constant tension of the skirt to afford a seal between the gasket and top surface under varying container finish tolerances. 4. A metallic snap-on, pry-off cap adapted to resist internal pressures and maintain a vacuum comprising a top and a skirt, the edge of the skirt being curled outwardly to form a circumferentially continuous wire edge, axially extending flutings in the skirt extending from substantially the cap top to the wire edge and formed continuously circumferentially of the skirt, and a plurality of lugs formed in said flutings by indenting the latter inwardly, thereby providing lugs in the zone of the flutings, said lugs being substantially V-shaped in cross section axially of the cap and having a major circumferential extent as compared to their axial extent, and the lugs being confined to the lower portions of the flutings in which they are formed whereby to retain unmutilated flutings thereabove, the lugs being reinforced by the flutings at the sides and thereabove.
ROBERT J. STEWART.