US3450291A

US3450291A - Bottle caps

Info

Publication number: US3450291A
Application number: US597739A
Authority: US
Inventors: Walter C Lovell
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-11-29
Filing date: 1966-11-29
Publication date: 1969-06-17
Anticipated expiration: 1986-06-17

Description

June 17, 1969 w LQVELL 3,450,291

BOTTLE CAPS Filed Nov. 29, 1966 Sheet of a Jnventor: Wa/[e/ 6. Love June 17, 1969 w. c. LOVELL 3,450,291

BOTTLE CAPS Filed Nov. 29, 1966 Sheet June 17, 1969 w. c. LOVELL 3,450,291

BOTTLE CAPS Filed Nov. 29, 1966 Sheet 3 of3 Patented June 17, 1969 3,450,291 BOTTLE CAPS Walter C. Lovell, 302 Williams St., Longmeadow, Mass. 01106 Filed Nov. 29, 1966, Ser. No. 597,739 Int. Cl. B65d 41/00, 41 /16 U.S. Cl. 21539 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to improvements in hottle caps and more particularly to improvements in manually removable crown caps and to methods of manufacturing such caps and of applying them to bottles.

Considerable commercial interest has developed in manually removable closures for liquid filled containers and more particularly for bottles filled with pressurized beverages such as carbonated soft drinks and beer. However, in order to be broadly acceptable, manually removable closures must meet difficult combined requirements of reliable sealing and a minimal price increment over the cost of highly developed standardized and inexpensive conventional crown cap. The economic aspects of successful marketing of a bottle closure includes avoiding the necessity for specially designed bottles to receive the closure and also avoiding the need for radically different capping apparatus. Stated another way, a proposed manually removable closure for a bottle is more readily acceptable if it can be applied to a standard beaded neck bottle either by conventional equipment or by such equipment after relatively simple and inexpensive modifications. Further requirements for broadest acceptance are that the closure be applicable to bottles without requiring a particular orientation and at a speed comparable to that of conventional crown caps.

An object of the present invention is accordingly to provide an inexpensive cap for reliable sealing of bottles while at the same time offering ease of manual removal without tools. A related object is to provide a manually removable bottle cap which is also adapted to being removed by a conventional opener.

Another object of the invention is to provide for the sealing of bottles with readily and inexpensively modified but generally conventional apparatus.

A more particular object is to avoid the need for maintaining orientation of caps being fed to bottle capping apparatus.

Still another object is to provide for the uniform and reliable sealing of liquid filled bottles with manually removable closures without requiring special and expensive modifications in the shape of the standard bottle neck.

In the achievement of the foregoing objects one feature of the invention relates to a short hollow plug seal formed on the interior of a metallic bottle cap shell and so disposed that when the cap is installed upon the neck of the bottle, the plug projects inwardly into the neck and forms a seal against the interior surface. The tightness of the seal is assisted by the pressure of the bottle contents which presses the plug into more intimate sealing engagement with the bottle neck in response to higher internal pressures. The plug is formed with a series of steps to accommodate to variations and gradations in internal neck diameter and out of roundness and the steps, under the pressure of the bottle contents improve sealing by providing in each bottle at least one line of seal under concentrated pressure. Because the seal is formed only where needed according to a method which provides both for maximum accuracy and uniformity in the formation of the seal, the cost of sealing material is very often less than that encountered in conventional caps.

The method of seal formation according to the present invention also results in an accurate seal without requiring extreme precision in the metering of raw sealing material into each cap. A quantity of conventional plastigel sealant is confined within a space defined between the cap shell and a tubular mold. Thereafter a piston slidable within the mold is pressed into the body of the sealant thereby forming a central cavity and urging the bulk of the sealant outwardly into engagement with molding surfaces. The important sealing surfaces of the plug are thus accurately molded while the piston is spring loaded to vary its distance from the shell to compensate for variations in the quantity of sealant. Inside the hollow plug the inner surface of the cap shell is covered by a sheath of sealant of variable thickness which assists in preserving the integrity of the seal. The sealant may be translucent and the sheath sufiiciently thin that advertising or other printed matter may be effectively displayed inside the plug.

The objects, features and numerous advantages of the present invention will be more fully appreciated from the following detailed description of an illustrative embodiment taken in connection with the accompanying drawings, in which:

FIG. 1 is a view in side elevation and partly in section of a crown cap assembly according to the present invention;

FIG. 2 is a bottom view of the cap assembly of FIG. 1;

FIG. 3 is a plan view showing the outline of the cap assembly of FIGS. 1 and 2 after its installation upon a bottle showing the form of a manual lift-off ledge or visor formed in the cap shell in the process of applying it to the bottle;

FIGS. 4 and 5 are views in side and front elevation respectively, more particularly showing the shape of the visor;

FIG. 6 is a view in side elevation and largely schematic in nature showing a cap being applied to a bottle by a capping head suitably modified to form the visor during the capping operation;

FIG. 7 is a view similar to FIG. 4 but in cross section showing the engagement of a sealing plug with the interior of the 'bottle neck; and

FIGS. 8 and 9 are progressive schematic views illustrating steps in the formation of the sealing plug.

There is shown in the drawings, particularly in FIGS. 1 and 2, a crown cap assembly according to the present invention, comprising a metallic shell 10 and a stepped sealing plug 12. The shell may be in the form of a conventionally fluted crown cap as shown in FIGS. 1 and 2 but the material of which it is made, its thickness, hardness and stiffness are essentially adapted to the pressure of the bottle contents and to the need for elastic and plastic deformation of the shell for manual removal of the cap assembly from the bottle. As is appreciated from FIG. 2, the cap according to the present invention is manufactured from a circular blank and there accordingly is no need that a particular orientation be maintained in the bottle capping apparatus. The plug 12 is preferably of a foamed plastigel and molded with concentric annular steps 14 of a diameter adapted sealingly to engage the interior of bottle necks within the commercial tolerance of a given size. The plug is formed with an interior cavity 16 concentric with the steps 14 and terminating in a thin sheath 18 which serves various functions in the present construction. One of these is to provide a barrier between the bottle contents and the metallic shell 10. A second function is that of preventing a pressure leak from developing between the plug 12 and the shell 10, since there is no opportunity for the pressure of the bottle contents to impinge between the plug and the shell to cause peeling of the plug from the shell. A further advantage of the sheath 18, as will be seen, is that it permits the formation of the steps 14 with a higher degree of accuracy, than could be obtained from reasonably attainable precision of usual plastigel dispensing and its subsequent treatment.

The cap assembly which thus far been described has, except for the presence of the plug 12, the general appearance of a conventional crown cap. The shell 10 includes a depending skirt 19 formed with a plurality of equally spaced flutes 20. A ledge or visor 21 is formed in the shell 10 as the cap assembly is applied to a bottle 22 as seen in FIGS. 3-7. The bottle 22 is of conventional form and includes a head 24 over which some of the flutes 20 of the shell 10 are crimped by a specially modified capping head 28. In order to form the visor 21, the head 28 is slotted at 30 so that a portion of the skirt 19, typically, approximately 90 of included are, is not crimped in engagement with the head 24 as best seen in FIGS. 3 and but is allowed instead to extend radially outwardly in the slot. Thus the visor 21 provides a convenient means for the removal of the cap assembly from the bottle neck by an upwardly directed force generally applied by the thumb of the user. The force required for raising the present cap from a bottle having a pressurized contents is usually no greater than 20 lbs. It will readily be appreciated that the force required for removal of the cap is generally proportional to the pressure of the bottle contents which must be resisted in order to provide the necessary tight sealing. Thus the material of the shell may be of aluminum or steel and its thickness and temper or hardness are chosen according to the contents of the bottle to which the assembly is to be applied. In general a shell of lighter weight steel or aluminum of hard temper is employed for capping bottles with either still or low pressure contents. A thicker gauge or hardness is required for some carbonated beverages in which the internal pressure may reach 90 p.s.i. The heaviest gauges and hardnesses are reserved for highly carbonated beverages and for beer and ale to be pasteurized because during pasteurization the internal pressure, at least temporarily, increases to the order of 140 p.s.i. or more. The function of the cap is to maintain the plug 14 in sealing engagement with the bottle as seen in FIG. 7. For this reason the shell 10 must be matched to the contents so as to prevent excess deflection of the shell which would permit leakage between the plug 14 and the interior of the bottle neck. At the same time the shell may be designed so as to deflect and cause leakage under abnormally high internal pressures which would otherwise cause bottle breakage.

The plug 12 may be formed in situ by compression molding, injection molding, casting or by other known methods or may be preformed and secured in place. The material of the plug 12 may be natural or synthetic rubbery material, e.g. natural rubber, synthetic rubber, polyurethanes, vinyl polymers such as polyvinyl chloride, and copolymers of vinyl chloride with vinyl acetate or other monomers, and other essentially linear thermoplastic polymeric materials known to have the necessary resilience and resistance to attack by the contents of the bottle for which the cap assemblies are intended.

A convenient and economical manner of forming the plug 12 on the inside of the cap shell 10 is illustrated in FIGS. 8 and 9. In the practice of the present method individual shells 10 each having had its interior surface lacquered are supported each in a nest 36 formed in a continuous belt 38 or alternatively in a rotary table and a body of plastigel 40 is deposited in each shell. The plastigel 40 is essentially of the type disclosed in United States Letters Patent No. 2,489,407 with the addition'of a quantity of blowing agent as is already well understood in the bottle cap sealant art. The body 40 is accurately meter into each cap but the precision of metering does not determine the accuracy of the sealing surfaces of the plug 12 because of the novel steps and apparatus employed in the formation of the plug. For this purpose the cap shell 20 containing the plastigel body 40, after being preheated to a temperature of approximately 300 F. for a period of approximately 45 seconds is indexed into a position in register with a tubular mold 42 in which there is slidable a piston 44. The mold 42 and the piston 44 are both heated to approximately 325 F. The mold 42 is lowered into engagement with the shell 10 to form between the mold and the shell a molding cavity containing the plastigel body 40. The piston 44 is then lowered into squeezing engagement under the urging of a pressure controlling spring (not shown) so as to force the bulk of the plastigel outwardly into that portion of the mold 42 which shapes the steps 14. Under the urging of the control spring the piston 44 more closely approaches the shell and thereby reduces the thickness of the sheath 18 when the body 40 is smaller and conversely the piston remains further away from the shell and thereby increases the thickness of the sheath 18 when the body 40 is slightly larger. Thus errors in metering of the quantity of plastigel into each cap are compensated by variations in the thickness of the sheath 18 which do not effect the sealing quality of the plug 12. The lower end of the piston 44 is chamfered as shown exaggeratedly for clarity at 46, to reinforce the base of the plug 12 by an integral continuous filler strip 48. The filler strip 48 although of minor proportions helps to resist the interior pressure of the bottle as a peeling force which tends to separate the plug 12 from the shell 10. The heated mold 42 and the piston 40 are maintained in contact with the molded body of plastigel as shown in FIG. 9 for a period of /2 to 1 second to cause the formation of a thin partially gelled skin on the molded plug so that the mold and piston pull cleanly away from the plug which retains its molded shape and adheres to the lacquered shell 10. Thereafter the cap assembly comprising the shell 10 and the plug 12 formed with its shape retaining skin is moved continuously through an oven at a temperature of approximately 350 F. for a period of 30 seconds to 60 seconds to complete the fluxing of the plastigel and to cause the activation of the foaming agent so as approximately to double the volume of the plug 12 from the condition depicted in FIG. 9. Alternatively, one of numerous plastisol compositions well known in the bottle sealant art may be employed but at a sacrifice in effective forming speed. The final result whether the indicated plastigel or another plastisol is used, is a homogenous rubbery foam plug having the step diameters and yield qualities to conform in sealing engagement with the interior of the bottle necks within the range of commercially available tolerances for a given bottle size.

In the removal of the cap assembly it is preferable that a pressure of 5 to 15 lbs. exerted upwardly by the users thumb upon the visor 21 be suflicient to cause outward camming of the flutes 20 so as to effect disengagement of the cap assembly from the head 24. For this reason it has been found advantageous to manufacture the shell 10 for sealing bottles filled with carbonated beverages in which the seal must withstand an interior pressure as great as p.s.i., of hard aluminum having a thickness of approximately .009". For sealing bottles containing beer to be pasteurized the stock for the shell may also be hard aluminum but having a thickness of .015". The shell 10 may alternatively be made of soft temper steel, commercially known as No. l temper, of substantially reduced thickness such as 65 pound template, to achieve the objects of reliability in sealing and ease of manual removal. Because the plug 12 extends into the neck of the bottle as shown in FIG. 7 and because the pressure of the contents of the bottle urge the lower end of the plug to flare outwardly into tight engagement with the interior of the neck, the present cap assembly presents a secure seal even with approximately of its slots uncrimped to provide the visor 20. In addition, because the seal is telescoping in nature a certain degree of outward deflection in the central portion of the shell 10 is tolerable without losing the tightness of the seal.

In applying the cap assembly to a bottle, it has been found advantageous to employ a total force of approximately 350 lbs. A compressible pad 50 within the capping head 28 yields under this capping force and insures the firm descent of the shell 10 without interposed sealant into firm contact with the top surface of the bottle as the plug 12 is guided into the interior of the neck. Guidance is afiorded to the plug 12 by the engagement of the shell 10 with the bead 24 since the plug is considerably shorter than the skirt 19. Except in cases of bottles having either wide variations in interior neck diameter or high contents pressure, a plug length equal to or less than /2 that of the skirt 19 has been found adequate.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination with a bottle having a neck terminating at its upper end in a bead, a crown cap formed of a circular blank and having a skirt clinched about a part of its periphery under the bead and another part of the skirt extending radially outwardly from the bottle neck to provide a visor adapted to be manually engaged to lift the cap from the bottle neck the distance to the clinched edge of the skirt being equal to the distance to the edge of the visor as measured from the center over exterior surfaces of the cap, and a hollow resilient plug within the shell extending in sea-ling engagement with the interior of 1 the bottle' neck a distance less than the length of the clinched skirt \and leaving the shell outside the interior surface of the bottle neck entirely free of plug material.

2. The combination according to claim 1 further characterized in that the plug consists of a plastic material.

3. The combination according to claim 1 further characterized in that the plug consists of a cellular polymeric material.

4. The combination according to claim 1 further characterized in that the plug is exteriorly formed with stepped sealing surfaces.

5. The combination according to claim 1 in which a sheath formed integral with the plug covers a flat portion of the inside of the shell within the plug.

6. The method of sealing a bottle comprising the steps of providing a cap assembly formed with a depending skirt of a circular blank and having an integral short hollow plug, bringing the plug into sealing engagement with the interior surface of the bottle neck only at the same time that the skirt is clinched about a portion of the periphery only thereby leaving a portion of the skirt extending radially outwardly from the bottle neck to provide a manual lift-01f visor, the distance to the clinched edge of the skirt being equal to the distance of the edge of the visor as measured from the center over exterior surfaces of the cap.

References Cited UNITED STATES PATENTS 2,543,775 3/1951 Gora 215-40 3,057,501 10/1962 Kroenert 215--40 3,169,656 2/1965 Wieckmann 215-40 3,300,072 1/ 1967 Caviglia 215-40 FOREIGN PATENTS 562,840 3/1957 Italy. 606,083 10/1960 Canada.

JOSEPH R. LECLAIR, Primary Examiner.

US. Cl. X.R. 5316, 42; 21546