US3273525A - Tamper-proof caps for containers - Google Patents

Description

P 20, 1966 F. G. ROBINSON 3,273,525

TAMPER-PROOF CAPS FOR CONTAINERS Filed Sept. 2, 1964 2 Sheets-$heet l INVENTOR:

R R K GUY POB/A/SOA/ p 1966 F. G. ROBINSON 3,273,525

TAMPER-PROOF CAPS FOR CONTAINERS Filed Sept. 2, 1964 2 Sheets-Sheet 2 INVENTORZ FKEDERICK GU y Roan/50M QMW 4, i

A rm (r 67 United States Patent 3,273,525 TAMPER-PROOF CAPS FOR CONTAINERS Frederick G. Robinson, Broad Balk, Kemp Road, Swanland, East Yorkshire, England Filed Sept. 2, 1964, Ser. No. 393,838 3 Claims. (Cl. 113-121) The present invention relates to a method of and means for forming ductile tamper-proof closure caps or ferrules for containers, such as bottles, cans, tanks and drums. These closure caps ordinarily consist of a dished metal shell, the sides of which are either straight or deformed to provide screw threads, with the skirt depending from the side being furnished with a rolled lowermost outer peripheral projecting rim or bead which engages a collar protuberance on the neck of the bottle to secure, by overflange action, the cap to the bottle opening. The lower bead of the cap is formed at one rolled fold thereof with weakening line which comprises a series of alternate cuts or slots and blanks.

Heretofore, weakening lines have been made by rotary action around the closure and not by a straight up and down reciprocating movement parallel to the axis of the cap. The art has long recognized the need for accurately gauging the depth of the score lines since, if not scored deeply enough, the cap will not tear or will tear unequally; and if the score lines are too deep when applied to a single thickness of metal material, tearing will occur through ordinary handling thereby defeating the tamperproof objective of the cap. There is a strong dislike for tear-off strips scored along banding lines because of the requirement for a very strong pull, the frequent need for a probe to start the tear and the frequent injury to the fingers and hand of the customer or user.

When closures according to the invention are initially detached from bottles by unscrewing and automatically rupturing the closure along the line of weakening provided in the bead, it will be found that the resulting raw edge with parts of the bridges remaining is tucked inwardly out of contact with the fingers of the user. The curve left on the cap adds strength tothe cap for its re-use.

Prior art examples of scoring a single thickness are found in US. Patents No. 2,367,317 and No. 517,580, the former patent showing weakened lines at the top edge of the lowermost skirt of the closure cap, these weakened lines made by rotary action of a cutting tool which produces frangible bridge adapted to be pulled away and .torn to break the losure.

In the US. Patent No. 2,175,350, a weakened bead edge is provided by milling and compressing, the milling step inducing an initial weakness by scoring and, further, by thinning the metal in the bead portion prior to folding. Upon compressional folding, there results a line of greatest weakness at the extreme outermost edge of the completely flattened, mill-weakened bead.

Closures according to the present invention are preferably sealed to bottles or like containers in well-known manner by rollingthe mouth or open end of the skirt under a shoulder provided on the bottle and are then provided with the line of weakening as described hereafter. However, the cap may be preformed according to the method of the present invention, and then sealed to the container by the conventional operation described above.

The object of the present invention is to provide a new and improved method of forming the line of weakening in closure caps or ferrules by the use of a non-rotatable reciprocatory press knife of predetermined contour. The contour of the press knife is adapted to slice completely through the thickness of that portion of the fold which constitutes the lowermost peripheral bead and to slice only partly through the thickness of the adjacent fold por- 3,273,525 Patented Sept. 20, 1966 tion of the bead with the exception of blanks or bridge at equally spaced distances which result from the shape of the cutting edge of the press knife. The second adjacent fold of the bead is partially cut because metals vary in thickness and the depth of the cut must be calculated so that the thickness of the first portion of the fold of the bead is sliced completely through in order that the cap may be removed for example unscrewed, yet be reusable thereafter.

In accordance with the present invention, the weakening line is formed only through one fold of the peripheral bead of the cap, e.g., through the lower fold of the bead, to provide an interrupted slot out completely through the entire thickness of the lower fold and through only a part of the thickness of the upper fold at its inner face. The upper fold of the peripheral bead is thereby formed with a corresponding interrupted cut groove of generally predetermined depth, which depth is controlled as a result of a single tool cutting operation; specifically, by reciprocating motion of a simple single non-rotatable tool with axial up and down cutting movement which collapses and knifes the bead, the tool consisting of a reciprocally movable non-rotatable cutter disc engaging the lower surface of the bead and a stationary disc-shaped bed which engages the upper surface of the bead. The movable cutter member is formed with two separate working faces; a first flat face of a shelf which extends radially outwardly from a location adjacent the lower, outer fold of the lowermost peripheral bead of the closure cap, and a V-shaped cross section cutting knife which is formed at the apex of a circular projection.

According to the invention, the weakening line is formed in the lowermost peripheral bead of the cap by engaging the bead between the appropriately ontoured cutting edge of a reciprocating cutting member and the co-acting relatively stationary bed disc, so that the lower fold of the bead is cut completely through this thickness and the adjacent upper fold of the bead is cut partly through its thickness at its inner face, with the exception of blanks or bridges in both folds which result from the shape of the contoured cutting edge.

Other objects of the invention will be apparent from the detailed description below. In order that the invention may be fully and clearly comprehended, it is described below with reference to a preferred embodiment illustrated in the accompanying drawings, in which:

FIG. 1 is an axial section of a screw-threaded closure blank, shell or ferrule whose skirt includes a rolled peripheral head or flange;

FIG. 2 is a similar view to FIG. 1 wherein there is also depicted a circular knife or cutter in engagement with the peripheral bead of the closure blank in collaboration with a relatively stationary co-acting member, according to the invention;

FIG. 3 is a much-enlarged view of the ringed portion A of FIG. 2;

FIG. 4 is a plan view of a fragment of the cutter shown in FIGS. 2 and 3 drawn to larger scale;

FIG. 5 is an axial section of FIG. 4; and

FIG. 6 is a similar view to FIG. 1 but showing a modified form of rolled peripheral bead or flange.

Similar reference numerals refer to similar parts throughout the several views.

To carry out the method of the invention, there is provided a circular knife or cutter which is shown in FIGS. 2-5. The knife comprises a circular disc 1 which has a central bore of a diameter substantiall equal to the outer diameter of the skirt of the closure cap blank 2.

The closure cap blank 2 is of circular shape having a flat top and cylindrical sides of uniform thickness.

Upon one face of disc 1 there is a circumferential cutting or knife edge 3 which is formed by the apex of a circular projection 4, which is of V-shaped cross section. The continuity of the knife edge 3 is interrupted at equally spaced intervals by a series of radial slots or gaps 5 of small width. The spacing may vary to accommodate different cap materials.

The movable cutter member is mounted for reciprocating movement in a headstock work-holder of conventional reciprocating machine which also mounts the stationary oo-acting disc-shaped bed 6 which is provided with a central bore corresponding in diameter to the upper threaded portion of the skirt of the closure cap blank 2.

Discs 1 and 6 are arranged upon the actuating machine in axial alignment, together with stop mechanism for arresting the traverse of the disc 1 towards the relative stationary disc 6, the traverse of the disc 1 being thereafter reversed. Preferably, the stop mechanism is adjustable.

When the bead or rolled portion 7 of a blank or shell, such as is illustrated in FIG. 1, is engaged by the cutter disc 1 with respect to the relatively stationary disc 6 (see FIG. 2), said bead is folded to collapse upper and lower wall portions against each other and the cutting edge 3 at the apex of the projection 4, by its axial up and down cutting movement slices completely through the lower thickness of the fold of the bead and partly through the upper thickness of the adjacent fold of the bead with the exception of bridges left by the slots or gaps 5. For example, assuming that metal of .010 inch thickness is to be dealt with, the knife or cutter is set to slice completely through the thickness of the lower fold of the bead ,7 and to a sufiicient depth in the inner face of the thickness of the upper fold of the bead to leave an uncut thickness of metal in the upper portion of .007 inch. Thus, there is left an uncut margin of .003 inch which ensures that the metal in the appropriate part of the bead has been completely out through, except for the bridges or blanks.

Thus, in a single operation and with a single tool, caps or closures can be produced in rapid succession with extremely high degree of accuracy, whereby after application to containers the caps can easily be unscrewed to rupture the blank portions of the weakening lines. If the groove or indentation in the lower fold of the peripheral bead, except for the bridges or blanks, is not knifed through completely, the caps become un screwable.

In order to further insure that the raw edge is completely out of contact with the fingers of the user, the bead or rolled portion 7 may be turned downwardly as shown in FIG. 6.

It is therefore proposed that the same tool which collapses and effects the knifing may be shaped to leave the bead or rolled portion turned downwardly; alternatively, if desired, the downward turn may be effected as a separate operation.

It should be understood that although the bead 7 is normally collapsed and knifed in one operation, the operation can, if desired, be a two stage one, i.e., collapsed and subsequently knifed, but this is not preferable because the objective of the invention is to achieve a tamperproof cap structure at lowest cost,

The material of the cap may be any suitable ductile substance such as flexible soft metal, e.g., lead, tin, or harder metals e.g., copper, aluminum or even of flexible injection molded plastic such as polyethylene, cellulose acetate, polycarbonate etc. All of this ductile materials have sufficient elasticity to be springy yet are sufficiently soft to tear readily under finger manipulation. The spacing of the interrupted cuts permits adjustment of ease of tearing to accommodate difference materials.

I claim:

1. In the method of manufacturing a ductile tamperproof cap which is reusable after opening, said cap having a lowermost peripheral bead and a skirt therebelow, said cap used as a closure for the mouth of a container having a neck and a shoulder on said neck, that improve ment in providing a weakened portion of the cap which consists of forming an interrupted line of weakening in said rolled peripheral bead of the closure cap on the shoulder of the neck of the bottle by the steps of compressing the upper and lower surfaces of said peripheral bead between an upper stationary pressing member and a lower non-rotatable pressing member which is reciprocably movable toward and away from said upper member to form upper and lower annular portions of the bead into flattened relation and folded against each other, said lower movable member having an outer pressing shelf and an inner knife edge, the continuity of said knife edge being interrupted by a series of equally spaced radial slots to thereby cut an interrupted circular line completely through the entire thickness of the lower fold of said compressed bead and partially through the thickness of the upper fold of said compressed bead by the axial up and down movement of said knife edge, said cutting being performed by the knife edge being confined at the juncture of the lower inner bead fold line and the dependent skirt, whereby the unscrewing of said cap automatically ruptures the closure along the line of weakening provided at the lower fold of said peripheral bead and the torn portions thereof curve inwardly after said rupture.

2. The method as claimed in claim 1, wherein said cap is formed and shaped by at the lowermost peripheral bead and skirt portion with the cap over the mouth of a container having a neck and a shoulder on said neck, and said pressing and cutting steps are carried out on the capped container.

3. The method as claimed in claim 2, wherein the compressing step and the cutting step are carried out simultaneously.

References Cited by the Examiner UNITED STATES PATENTS 517,580 4/ 1894 Livingston. 3,001,657 9/1961 Gamble 215-42 3,139,211 6/1964 Bogner 220-48 CHARLES W. LANHAM, Primary Examiner.

THERON E. CONDON, Examiner.

J. B. MARBERT, Assistant Examiner.

Claims (1)

1. IN THE METHOD OF MANUFACTURING A DUCTILE TEMPERPROOF CAP WHICH IS REUSABLE AFTER OPENING, SAID CAP HAVING A LOWERMOST PERIPHERAL BEAD AND A SKIRT THEREBELOW, SAID CAP USED AS A CLOSURE FOR THE MOUTH OF A CONTAINER HAVING A NECK AND A SHOULDER ON SAID NECK, THAT IMPROVEMENT IN PROVIDING A WEAKENED PORTION OF THE CAP WHICH CONSISTS OF FORMING AN INTERRUPTED LINE OF WEAKENING IN SAID ROLLED PERIPHERAL BEAD OF THE CLOSURE CAP ON THE SHOULDER OF THE NECK OF THE BOTTLE BY THE STEPS OF COMPRESSING THE UPPER AND LOWER SURFACES OF SAID PERIPHERAL BEAD BETWEEN AN UPPER STATIONARY PRESSING MEMBER AND A LOWER NON-ROTATABLE PRESSING MEMBER WHICH IS RECIPROCABLY MOVABLE TOWARD AND AWAY FROM SAID UPPER MEMBER TO FORM UPPER AND LOWER ANNULAR PORTIONS OF THE BEAD INTO FLATTENED RELATION AND FOLDED AGAINST EACH OTHER, SAID LOWER MOVABLE MEMBER HAVING AN OUTER PRESSING SHELF AND AN INNER KNIFE EDGE, THE CONTINUITY OF SAID KNIFE EDGE BEING INTERRUPTED BY A SERIES OF EQUALLY SPACED RADIAL SLOTS TO THERBY CUT AN INTERRUPTED CIRCULAR LINE COMPLETELY THROUGH THE ENTIRE THICKNESS OF THE LOWER FOLD OF SAID COMPRESSED BEAD AND PARTIALLY THROUGH THE THICKNESS OF THE UPPER FOLD OF SAID COMPRESSED BEAD BY THE AXIAL UP AND DOWN MOVEMENT OF SAID KNIFE EDGE, SAID CUTTING BEING PERFORMED BY THE KNIFE EDGE BEING CONFINED AT THE JUNCTURE OF THE LOWER INNER SEED FOLD LINE AND THE DEPENDENT SKIRT, WHEREBY THE UNSCREWING OF SAID CAP AUTOMATICALLY RUPTURES THE CLOSURE ALONG THE LINE OF WEAKENING PROVIDED AT THE LOWER FOLD OF SAID PERIPHERAL BEAD AND THE TORN PORTIONS THEREOF CURVE INWARDLY AFTER SAID RUPTURE.

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