US3463107A - Can end and method - Google Patents

Description

B. B. LJPSKE CAN END AND METHOD Aug. 26, 1969 3 Sheets-Sheet l Original Filed May 26, 1965 /N vE/v TOR. BEIVJM//V 5. L PSKE Aug. 26, 1969 B. a. LIPSKE can END AND muon 5 Sheets-Sheet 2 Original Filed May 26. 1965 xix Ff Tf /558/48 l Il Aug. 26, 1969 B. a. LlPsKr;

CAN END AND METHOD 3 Sheets-Sheet 5 Original Filed May 26, 1965 /fv VEA/TOR.

BE/VJ M//V B. L IPS/(E United States Patent O 3,463,107 CAN END AND METHGD Benjamin B. Lipske, Greenvale, N.Y., assignor to National Can Corporation, Chicago, Ill., a corporation of Delaware Original application May 26, 1965, Ser. No. 458,932, now Patent No. 3,383,008, dated May 14, 1968. Divided and this application Dec. 21, 1967, Ser. No. 692,369

Int. Cl. B21d 51/00 U.S. Cl. 113-121 4 Claims ABSTRACT F THE DISCLOSURE An easy opening can end with a line of weakness deining a tear out portion in the end, a linger tab attached to the tear out portion by a fastener which extends through both the end and the tab, and a synthetic resin material forming a seal covering the opening in the can end through which the fastener extends to prevent leakage of gas therethrough.

In some embodiments, the fastener is a rivet which has a square, serrated, or like shaped shank to prevent rotation of the rivet inside the can end, and, in some embodiments, the sealing material is located in an embossed or recessed area near the rivet. Processes for making the easy opening end are also described.

This application is a division of my earlier tiled case, application Ser. No. 458,932, liled May 26, 1965, and now Patent No. 3,383,008, issued Mal 14, 1968.

The present invention generally relates to easy opening can ends, and more particularly to ends for so-called tin cans in which a lifting tab, or portion adapted to be grasped by the fingers of the user, is attached to a preselected, weakened area of the can end by means of a rivet which is a rivet which is a separate part from the can end, and which may be separate from the lifting tab.

Easy opening can ends are in great commercial demand, and billions of such can ends are sold every year in the United States. However, prior known easy opening can ends have been generally faced with the problem of providing a practical and economical construction in which the product must be protected from contamination entering the can from the outside thereof. Accordingly, the constr-uction or prior known easy opening can ends is of a type wherein the rivet or connecting means for attaching the tab to the portion to be torn out from the can end is integrally formed with the can end. Such constructions possess a number of advantages, but, nonetheless, in spite of their substantial commercial success, such easy opening ends have been difficult to manufacture, particularly in view of the nature of the rivet which must be formed in order to afford a satisfactory product. These rivets are well known in the can making art. The principal disadvantage of such can ends is that an extremely high degree of quality control is necessary, and accordingly, large numbers of rejects occur, and the complex inspection and testing techniques which are required tend undesirably to raise the cost of making such can ends.

Can ends of the type referred to above are commercially made of aluminum, inasmuch as it is impossible to form a rivet of this type satisfactorily from tinplated steel. Thus, commercialy satisfactory easy opening tinplate ends are not presently known in the United States.

Composite ends are known wherein an aluminum insert is crimped in place in an opening formed in a tinplate end, but the process of making such ends requires equipment which will perform the desired punching,

r' lCC crimping and sealing operations in an off-center location relative to the can end, and accordingly such equipment is highly complex and expensive.

The present invention, however, provides not only an end which may advantageously be made from aluminum, and which may be made without the quality control problems associated with the aluminum ends of the prior art, but also and further makes it possible, for the first time, to make a practical, easy opening type tinplate end having the advantages of simplicity and low cost.

An additional advantage of the present invention of forming an easy opening end, particularly the removable portion 30 thereof, from tinplate, is that retrieval of the cut and discarded portions of an end may be readily recovered from beaches and streets, for example, reducing the safety hazards attendant thereto. When such ends are made from aluminum, magnetic methods of retrieving them are impractical.

In brief, the present invention provides a can end in which a desired pre-selected area is scored or partially cut, and an end in which a portion of this scored area is thereafter attached by a non-integral rivet to a lifting tab designed to be lifted by the fingers of one manipulaing the end. That portion of the can end through which the rivet extends is adapted to be protected from the contents of the can and from the atmosphere, in the use of the device, by covering it with a coating 0f a substantially gas-impermeable plastisol or like resinous composition.

The use of the interior seal comprising the plastisol covering the base of the rivet, in combination with the other features of the invention, makes possible a simple and inexpensive easy opening can end having a number of desirable advantages and characteristics. The present invention, including the manner in which its objects and advantages are attained, will be better understood when considered in conjunction with a description of the preferred embodiments of the invention, as set forth in the specification and claims herein, and as shown in the accompanying drawings, in which like numbers indicate corresponding parts throughout, and in which:

FIG. 1 is a top plan view of one embodiment of the easy opening can end of the present invention;

FIG. 2 is a vertical sectional View of the can end of FIG. 1, taken along lines 2-2 thereof;

FIG. 3 is a greatly enlarged vertical section view of a portion of the can end of FIG. 1, taken along lines 3--3 thereof;

FIG. 4 is a bottom plan view of the end shown in FIG. 1;

FIG. 5 is an enlarged vertical sectional view of a portion of the end shown in FIG. 1, taken along lines 5-5 thereof;

FIG. 6 is a vertical sectional view of a modified form of the present invention;

FIG. 7 is a greatly enlarged vertical sectional view of a portion of the modified end shown in FIG. 6;

FIG. 8 is an isometric view of a rivet used in the present invention;

FIGS. 9 through 15, inclusive, are vertical sectional views through a can end, demonstrating sequential steps in one of the processes by which the can ends of the present invention are formed;

FIG. 16 is a top plan view of a modified form of the easy opening end, showing a modification of the linger tab member;

FIG. 17 is a vertical sectional view of the tab member taken along line 17-17 of FIG. 16;

FIG. 18 is a top plan view of a further modified form of the easy opening end;

FIG. 19 is a vertical sectional view of the tab member taken along line 19-19 of FIG. 18;

FIG. 20 is a -top plan view of a further modified form of the easy opening end;

FIG. 21 is a vertical sectional view of the tab member taken along line 21--21 of FIG. 20.

Referring now to the drawings, in greater detail, there is shown generally in FIG. 1 a can end which is adapted to be received, as by a conventional double seam, over the end of an ordinary tin can, a libre or so-called composite container, or the like. The can end, E, is shown to have a ilat central portion 22, a generally vertically upstanding wall portion 24, a top outer edge portion 26, and an outermost curl 28. As is well known in the art, in an end such as this, those portions 24, 26 and 28 will form, in combination with the sidewall of the container, a double seam, wherein the wall 24 becomes the countersink of the end, and the curled surfaces 26 and 28, are incorporated into the seam proper.

A removable portion 30 of the end E is defined by a scored line 32 which extends on one end to a point generally centrally of the can end, and, on the other end, to a location adjacent the edge of the wall 24 of the end E, the line 32 thus forming, in this embodiment, a continuous closed loop. The form of the removable portion defined by scored line 32 is conventional in the art, and forms a part of the present invention only in combination with the other features thereof. In a typical shape for use with beverages, the radially inner portion 34 of the removable portion 30 is generally used as an air vent, and is somewhat narrow, whereas the larger end portion 36 is located radially outwardly, and is used to empty the contents of the container therefrom. Variations in the shape of the scored line may be made as, is well known in the art, and as will be discussed further herein. In the drawings, for purposes of illustration, the width of the score line 32, is shown as being somewhat greater than is normally the case.

A central opening 38 is formed in the center of the end E, and the shape of this opening 38 is square in this embodiment of the invention. The opening 38 is adapted to accommodate a rivet 40 which includes a square shaped shank portion 42, a lower ange 44, and a top head 46. In the assembled form of the can end, a lift tab 48 is held in place over the opening 38 by the head 46 of the rivet 40. The tab 48 includes forwardly extending sections 50, the purpose of which will be described in greater detail herein. The lift tab `48 preferably includes, in this embodiment, double thickness, turned under marginal edge portions `52 (FIG. 3) and a at, rivet-receiving portion 54 therein. The ange 44 of the rivet 40 is covered over its entire extent on the inside of the end E by a plastisol sealing material 56, the composition of which will be referred to in greater detail herein.

In all the embodiments of the invention, the plastisol 56 tenaciously adheres both to the can end 20 and the flange 44 of the rivet 42 to provide a seal, and consequently, in some embodiments, it is desirable that the shank 42 and the opening 48 accommodating it, be noncircular so that the rivet will not undesirably rotate and destroy the seal between the plastisol 56 and the end E.

In an alternate form of the invention, a round shank rivet is provided, but the opening 58 in the tab 48 (FIG. 13), is made considerably larger than the shank 42 of the rivet 40 so that rotation of the tab 48 will not rotate the rivet 40, and destroy the adhesion between the end E, the rivet 40, and the plastisol seal 56.

In an alternate form of the present invention, illustrated in FIGS. 6 and 7 herein, it is shown that the marginal edge portions 60, of the end E, surrounding and forming the opening 38, are raised upwardly, in the orientation shown in FIGS. 6 and 7. In this way, when the riveting operation is completed and the tab 48 is fastened to the end E, the end may be inverted and the recess defined by the edge portions `60 provides means whereby the plastisol covering 56 will remain localized in an area adjacent the rivet ange 44.

Further advantages of the non-integral rivet and rivet seal construction just referred to will become more apparent as the description relating to the process of manufacture proceeds.

The tab 48 is shown as including two outwardly extending projections 50, which, in the use of the device, may move downwardly as the radially outer edge portion of the tab 48 moves upwardly, whereby the projections 50 serve as a fulcrum for the tab 48. This construction possesses further advantages when the end is made from tinplate, because greater initial effort is need to open the tougher tinplate end, and accordingly, the additional mechanical advantage provided thereby may be utilized. The folded over outer edge portions 52 of the tab 48 provide the stiffness in the tab necessary for opening the container without bending the tab 48.

The preferred process for making the easy opening ends of the present invention is somewhat diagrammatically indicated in FIGS. 9 through l5, inclusive. Basically, the steps comprise selecting a blank of raw material for an end E, and punching the opening 38 therein at the same time the end itself is punched or cut from sheet stock, on conventional double die presses for example, and prior to the time the curl 28 (FIG. l2) is imparted to the end. FIG. 11 shows the edge portions 60 forming the recess which may, if desired, be impressed into the end when the opening 38 is punched out.

Thus, FIG. 9 shows an end E which might be stamped by conventional double die stamping presses. This end includes a central portion 22 and a top outer edge portion 26, before a curl is formed.

FIG. l0 shows the same end E, but the end includes the opening 38 which is formed by a suitable addition to the die used in the double die press.

FIG. 11 shows the marginal edge portions 60 near the opening 38 forming a recess surrounding the opening 38. This recess may be formed contemporaneously with the punching of the opening 38. In the practice of the invention, the recess and opening are formed in the same operation that cuts the end.

FIGS. 12 and following show that the curl 28 has been added to the outer edge of the ends. Curlers are conventional in the art and are well known. Their use to impart the curl forms no part of the present invention, and the curler may be used at whatever stage is desired in the process.

As illustrated in FIG. 12, a rivet 40 with the flange 44 formed thereon, is inserted through the opening 38 and a mandrel 64 is moved into position from below the support the rivet 40 in the desired position, as shown. The tab member 48 as shown in FIG. 13 is moved into the desired position with its opening 58 disposed above the upstanding shank 42 of the rivet 40. This tab 48 may, as is now conventional in the manufacture of easy opening ends, be formed shortly before attachment and immediately thereafter fed into the position shown in FIG. 13 by conventional means known to those skilled in the art.

In FIG. 14 the tab 38 is shown to be lowered over the shank 42 of the rivet 40, and the riveting mandrel 66 is shown to be in position for forming the head 46 on the rivet. Thereafter, the end is inverted and the plastisol covering 56 is deposited in the desired location, whereupon the plastisol 56 is cured by known means, such as by placing the end briefly in an oven or the like.

If a recess 60 is stamped into the end E, the plastisol 56 may be deposited centrally of the recess in a viscous state, and the end may then be rapidly rotated or spun to distribute the plastisol over the recess 60, in the even covering, by centrifugal force. If desired, the end seam lining compound may be deposited at the same time the plastisol is deposited. The end seam lining compound, known as compound liner in the art, is shown at 92 in FIGS. 12 and l5 only. This illustrates the fact that the compound liner may be applied at any time after the curl is formed. The manner of applying the liner is also com ventional, namely by die lining or by a nozzle deposit system, such methods being known to those skilled in this art.

In the steps referred to above, illustrating the process of the invention, and as referred to in the claims, are described in a preferred order, but their performance in the exact order indicated is not strictly necessary to the invention and is not intended to be so limited herein or in appended claims. For example, the recess 60 may be put into the end after forming the opening 38. The opening 38 may be formed after the end is cut and curled; if desired, the entire process may `be performed in a manner upside down relative to that shown in FIGS. 12 through 14, that is by placing the head 46 on the rivet on the inside surface of the can end E and leaving the preformed rivet head or ange 44 on the exterior thereof.

The process for cutting the score lines may be accomplished simultaneously with the placing and riveting of the tab 48 on the end, yor may be accomplished therebefore. This process is well known in the art, and is accomplished by striking the end on the top surface thereof with a scoring punch of the desired configuration.

Another optional step in the process of the present invention comprises so-called post-repairing of the arca of the end which is scored. The reasons for this operation, and applicants novel method thereof are discussed below.

Normally, a problem is encountered with easy opening can ends of the type in which a scored or partially cut through portion is formed therein. In the manufacture of can ends, the metal from which the end is made is treated, as by placing one or more coats of lacquer or enamel thereon. For example, a modified epoxy resin primer, an oleoresinous primer, a phenolic primer, or like coating is applied to the end. A second, additional coating of a vinyl chloride-vinyl acetate copolymer may be applied over the primer. Certain of the coatings such as epoxy or phenolic type coatings, may not require primers, and accordingly the material from which the end is made may be one or more coats of the materials referred to above.

When the cutting or scoring operation is performed on the can end to define the region of weakness riveted to the finger tab portion, the bottom or inner end of the can end will often have the organic coating deposited thereon abraded or cracked. This breaking of the integrity of the coating results from the ow of the metal under impact and from the force of being struck by the die or punch impressing the score.

Where ends used for beer or like beverages are made from aluminum, small cracks or discontinuities in the coating are not necessarily deleterious, because metallic aluminum does not harm, and may in fact enhance, the flavor of the beer or ale.

However, because of the acidity and because of 4other reactive components present in soft drink beverages, and other foods and drinks, it is essential that the coating extend continuously over the can end. Accordingly, soft drinks and the like rapidly corrode metallic aluminum, especially in the area where the end is of decreased cross sectional thickness becaue of the score line. Thus, a socalled post-repairing or further coating of scored aluminum ends is required before such ends are suitable for use with many of the products referred to above. In addition, the problem of corrosion exists in the case of all foods and beverages, including beer and the like, when a tinplated steel end is used. Thus, a post-repairing or interior coating operation is required Ion all tinplate ends.

Altough it has been suggested that the coating operation remain to be performed after the end is formed, this is impractical in the can industry because the coatings are necessary to reduce friction in the curling and seaming operations performed `on the can ends, and because it is impractical to apply an even, uniform coat to an already formed individual piece, such as a can end, of complex non-planar shape. The present invention overcomes this diiculty by coating the end, after it has been scored, with an interior coating material which will adhesively adhere to the primer or interior finished coating. After being sprayed with a coat of this material, the end is cured by passing it through a Hash oven where it is cured for one minute or less at 400 F. This novel method of post-repairing the scored end of the type referred to herein or other known scored easy opening ends is simple and effective and eliminates the need for placing a wax or like coating on the ends, or for performing other more cornplex and less desirable operations to bring about the results set forth above.

In addition, this post-repair operation serves to coat the flange 44 of the rivet 40 to promote adhesion of the plastisol 56 thereto, and thereby preserve the strength and gas-impermeability of the can end unit.

Referring now to FIGS. 16 through 2l inclusive, other variations of the invention are shown. For example, in FIG. l6 a lifting tab is shown which comprises a circular opening 70 surrounded by a generally ring-like member 72. As is best shown in FIG. 17, this ring 72 comprises a at top surface portion 74, and inner and outer folded under bottom surfaces 76 and '78 respectively. In this construction the edges 76, 78 are rolled under so that there are no sharp edges projecting inwardly into the opening 70 formed by the ring 72. The tab 48 includes a relatively flat rivet engaging front extension portion 80 adapted to engage the rivet 40, in the manner set forth above. The score pattern illustrated may be used, if desired.

FIG. 18 shows a tab member 48 comprising an outer loop 82 of wire, adapted to be grasped by the fingers, and an inner loop 84 closely surrounding the rivet 40. In this construction, the wire is smooth and round, and presents no rough edges to pose a cutting hazard to the lingers of the person manipulating the tab for removing the scored portion of the end.

FIG. 20 shows a form of tab 48 in which two somewhat centrally disposed stiiening ribs 86 are provided for the tab, and forward extensions 88 thereof may serve as a fulcrum for the lift tab 48. An upwardly turned outer radial edge surface 90 may be provided to facilitate lifting the tab 48 when it is held in close contact with the can end E.

The configuration of the scored lines 32 imparted by the scoring punch may assure the alternate forms shown in the lines shown in FIGS. 16, 18 and 20. These are fully opening ends, and may be provided as easily as beverage ends, differing therefrom only in the shape of the score pattern cut in the end.

The materials used in making the can end E of the present invention may be entirely aluminum or aluminum alloy, of the types and grades conventionally used for making aluminum can ends, normally 5082-H19 type aluminum alloy, of .0145" thickness, for example. In the alternative, the end E and the tab 48 may be made of tinplate, and the rivet 40 of aluminum or, all the elements or any combination may be made of any of the above materials, However, a soft and malleable material such as aluminum is generally preferred over a harder material for the rivet 40. If the end is constructed of tinplate, a thickness of from about 0.006- to about .0100 is preferred, although thicker ends are sometimes used.

The thickness of residual portion 62 remaining under the score line 32 (FIG. 5) will normally be, in the ycase of an aluminum end, about 0.004 to 0.005 inch and in the case of a tinplate end, about 0.002 to 0.003 inch.

The material referred to above as plastisol 56, and used to cover the portion of the end surrounding the opening 38 and the rivet 40, is preferably a plastisol material of a type well-known in the can and bottle cap industry. Although by plastisol it is technically meant a dispersion of vinyl resin in a plasticzer, other materials are suitable for use in this invention, subject to the limitations set forth herein. The material for use must be approved by the Food and Drug Administration,

in the event that the product is to be used for human consumption. Otherwise, such as in the case of motor oil and like products, any material compatible with the pressure and/or vacuum requirements and compatible with the contents of the container, may be used.

Plastisol and like synthetic materials suitable for use in the present invention are Well known, and the characteristics of some of these are listed below:

A typical plastisol material I have found suitable for use in this invention comprises a vinyl chloride resin, or vinyl chloride resin copolymerized with small amounts, say or less, of vinyl acetate and/or vinyl alcohol. These resins are insoluble in, but dispersable in, typical plasticizers, such as dioctyl phthalate, dioctyl sebacate, diphenyl phosphate, tricresyl phosphate and the like. After the resin is dispersed in the plasticizer, it may be cured, as by heating 350 F. or more, whereupon solvation of the resinous component takes place, and the resulting cured composition is in the form of a solvated plastic, that is, an organic glass, solid solution, or ultra-high viscosity fluid, being somewhat llexible, and having excellent adhesion to the primers or inner end coatings referred to above.

Thus, a suitable material comprising 100% solids content is preferable for use in the present invetnion. Owing to manufacturing operations and speeds, a solvent base or volatile componnet system does not lend itself to advantageous application of such sealing material.

The materials referred to above are typically selected as those having the capability of adhering to the ordinary coatings applied to can ends, whether by way of the postrepairing operation referred to above, or otherwise. That is, such sealing material should be capable of tenaciously adhering to both enameled and enamel-free can ends. Typical interior coating enamels used on such lcan ends comprise, for example, oleoresinous lacquers or enamels, such as tung oil or linseed oil based materials, epoxy phenolics, epoxy esters, vinyl chlorides, modified vinyls or copolymerized epoxy phenolic type synthetic resin coatings.

On the other hand, some can ends are not coated, and the plastisol should adhere equally well thereto.

It will be noted that although the plastisols referred to above have a certain small but measurable permeability to gases, the design of the opening and the rivet therefor is such that the total area available for gas permeability is extremely small. Thus, for practical purposes a gas-impermeable end may be provided by the present invention, although the seal material itself does have a measurable permeability to gases. In addition, other extrinsic factors, in practice, limit the shelf life to beverages and other like products possessing positive pressure or vacuums, to three to six months or less, thereby obviating the need for a permeability equal to that of a unitary metal end. Thus, the word gas-impermeable, as used herein, andas used in the appended claims, refers to a substantial, practical, although not necessarily complete, gas impermeability.

The other organic composition used in the present invention is the compound liner 92 referred to above. Typical compositions of such material generally comprises rubbery materials, for example, GR-S rubber (butadienestyrene), or butyl rubbers, chloroprenes, chlorinated isoprenes, butadiene-acrylonitrile copolymers, isobutylenes, chlorinated polyethylene rubbers or mixtures thereof. These materials are lined by the methods referred to above, in the form of water dispersion or in solvent based systems. Thereafter, the water or solvent is evaporated by air drying or heat, and the end is ready for the next step in the process.

It will thus be seenA that the present invention provides a novel can end having novel advantages and characteristics, including those hereinbefore pointed out and others which are inherent in the invention.

It is also understood that certain codications of the can end of the present invention may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. A method of making an easy opening can end comprising the step of,

(a) forming a can end from a blank of sheet material,

(b) forming a rst, rivet-receiving opening in said end blank, said opening having a definite profile,

(c) scoring at least one line of weakness in said end blank in a form wherein said line at least partially surrounds said opening,

(d) inserting a rivet with a cross sectional shank profile corresponding substantially to the profile of said rst opening, said rivet including a preformed head on one end thereof,

(e) forming a tab adapted to be grasped by the lingers, and forming a second rivet-receiving opening in said tab,

(f) placing said second opening in said tab in a registering and overlying relation to said rivet and said can end,

(g) forming a head on the other end of said rivet,

(h) covering said rivet, and the portion of said can end immediately surrounding said rivet, with a resinous, substantially gas-impermeable sealing ma terial and (i) curing said sealing material, whereby an easy opening, substantially gas-impermeable can end member is provided.

2. A method of making an easy opening can end as defined in claim 1 which additionally includes the step of forming a recessed area in that portion of the can end immediately surrounding said first opening, said recess being adapted to receive said resinous sealing material therein, and extending upwardly from the plane of said can end, when said can end is in position of use on the top surface of a can.

3. A method of making an easy opening can end as defined in claim 1 which additionally includes the step of covering that surface of the can end which will become the inside surface thereof in use with an additional layer of a can coating material in order to cover discontinuities caused by said scoring, and curing said can coating material at a temperature of at least 250 F.

4. A method of making an easy opening can end as defined in claim 3 wherein said can coating material is applied by spraying.

References Cited UNITED STATES PATENTS 3,294,275 12/ 1966 Mileto et al. 220-54 3,361,291 l/1968 Fraze 113-121 RONALD D. GREFE, Primary Examiner

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