DK142022B - Lightweight metal closure cap. - Google Patents

Description

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BACKGROUND OF THE INVENTION The present invention relates to a lightweight metal closure cap intended to be secured over a bead along the opening of the neck of a container consisting of a disc-shaped top portion and a circumferential, hanging collar with a smooth, cylindrical surface which below ends at a free, substantially circular edge, extending along the collar and into the top portion a pair of attenuated tear lines defining a tear strip forming an integral portion of the collar and top portion 10 extending downwardly from the free edge as a short extension of the collar, and then radially outwardly away from it as a gripper to facilitate tearing.

The attenuated tear lines must be strong enough to withstand the internal pressure in the container to which the closure cap is placed and partly to be torn by a moderate pull in the tear strip of the tear strip, and it is therefore important that their strength is not affected by various factors. during manufacture and application to the container.

However, this poses a problem in that the weakening lines of closure caps of the kind in order to achieve the desired accuracy are produced in a flat blank of the cap, and this accuracy deteriorates during the subsequent printing operation, during which a substantial peripheral portion of the plane blank is pressed in the form of a cylinder to form the collar of the cap. During this printing operation, the circumference of the peripheral portion is progressively reduced from the original outer diameter of the blank to the diameter of the top portion of the cap from which the collar exits.

30 The stresses resulting from the printing in the metal of the closure cap cause a metal displacement which is concentrated mainly by the lines of weakening, which are particularly exposed due to the smaller metal thickness, and the detrimental effect is increased by the gripping portion of the tear strip, whose stiffness in the circumferential direction prevents it. in being deformed. To compensate for the stiffness of the gripper part U2022 has 2

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earlier attempts were made to solve the problem by supplying the cap collar with notes or cuts from the free edge of the cap immediately at the gripping section. However, since the gripping portion is relatively wide relative to the circumference of the cap, it still provides an undesirable resistance which contributes to the transfer of the deformation to the lines of weakness.

It is the object of the invention to solve the problem in a manner which substantially eliminates the effect of the stiffness of the gripping member, and for this purpose a closure cap of the type according to the invention is characterized in that in the tear strip there is a radially elongated slot which is placed in the short extension of this strip.

Hereby, the former resistance will no longer occur, the tear strip itself acting to receive 15 the circumferential movement of the metal during the printing by closing the slot gradually as the diameter of the collar decreases. This reduction is particularly noticeable at the free edge of the claim, and according to the invention, the closure cap is therefore conveniently made in such a way that the slot in the tear strip extends inwardly within the lower edge of the capsule claim and outwards in the tear portion of the tear strip.

Previously, closure caps with a radially directed slot have been proposed, but not in such a way as to solve the problem of unwanted deformation in weakening lines 25 during the closure of the closure cap on a container. According to the disclosure of U.S. Patent No. 1,107,522, e.g. a slot in the collar of the closure cap, but not in the protruding tear tab. The intention is that after the tear of the tab, the slot should be opened at one end, thereby allowing easy removal of the cap. Thus, there are and are no need for lines of weakness with problems that result.

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Also, as described in U.S. Patent No. 2,433,629, a slot has been proposed in the tear tab rather than in the collar cap. The purpose of this is, as with the aforementioned arrangement, not to solve any problem with weakening lines not used in this closure cap, but to enable the cap to be removed by opening the slot, here only by bending rather than by tearing.

The idea of a slit which, by bending a protruding tab, opens and enables the closure cap to be removed, also forms the basis of the arrangement disclosed in British Patent No. 399,933, in which the two aforementioned arrangements have been combined by to allow the slot to extend both in the hood collar and in the tab. Nor can any of this arrangement teach that the slot can be used to secure the desired strength of weakening lines formed prior to a flat blanking cap and thereby subject to damaging deformation during the printing of the claims. The risk of such deformation is even particularly high in closure caps of the kind that are the starting point of the invention, since the cap's hanging collar here has a smooth, cylindrical surface and no corrugation that could possibly absorb some of the metal displacement.

The invention will be explained in greater detail in the following with reference to the drawing, which shows some embodiments of the closure cap according to the invention.

In the drawing, FIG. 1 is a bottom view of a blank for use in forming the closure cap in the preferred embodiment of the invention; FIG. 2 is an enlarged sectional view taken along line II-II of FIG. 1 in the direction of the arrows; FIG. 3 is a partial sectional view taken along line III-III of FIG. 1 in the direction of the arrow; FIG. 4 is a front view of the finished cap; FIG. 5 is a partial vertical section taken along line V-V of FIG. 4 in the direction of the arrows; FIG. 6 the front view of the cap and placed on a container neck,

5 FIG. 7 is a partial vertical section along line VII-VII

in FIG. 6 in the direction of the arrows; FIG. 8 is a perspective view of part of a finished cap as shown in FIG. 4 as seen from the side of the tear-off tab, FIG. 9 shows a similar view after the cap is attached to a container neck or bottle neck as shown in FIG. 6, FIG. 10 is a bottom view of a modified embodiment of the hood blank; FIG. 11 in a similar manner to FIG. 6 is a cap formed from the blank of FIG. 10, 15 FIG. 12 in a similar manner to FIG. 1 is a hood blank provided with weakening lines on the opposite surface; FIG. 13 on a larger scale a partial. section along line XIII-XIII of FIG. 12 in the direction of the arrows; and FIG. 14 in a manner similar to FIG. 4 shows a cap provided with weakening lines on the outside formed by the blank of FIG. 12th

As seen in FIG. 4 and 5, the cap as a whole denoted by 1 comprises a flat, flat top 2 surrounded by a hanging collar 3. At the transition between these, there is a rounding 4. The collar 3 ends in a downwardly extending collar. facing free edge 5, however, not at the location from which a tear-off tab 6 exits. The tab 6 extends a short distance directly down from the collar as a neck portion 7 and then points radially outwardly with an inclined downward slope away from the cap. The side edges 8 and 9 of the tab approach each other from the free edge of the collar to the rounded end 10 of the tab.

The inner surface a or outer surface b of the cap 1 is provided with a few lines of weakening. These 35 may follow any particular pattern in their course across the cap, e.g. can differ from one another outwards either with curved or straight lines. According to FIG.

1, 4 and 5, lines of weakening are formed in the inner surface a of the cap and are comprised of portions 11 and 12 extending over the cap of the cap, and portions 13 and 14 extending over the collar 3 substantially parallel as shown in FIG.

5 1 and 4. Accordingly, a tear strip 15 is formed between the weakening lines as a continuation of the tab 6, extending substantially over the cap.

The complete cap blank 20, of which the cap of FIG. 4 and 5 are shown fully drawn in FIG. First

10 Parts of the workpiece are shown in FIG. 2 and 3 on a larger scale, FIG. 2 is turned upside down with respect to FIG. 1. It is seen that the blank 20 is formed with grooves 21 and 22 at the transition between the sides 8 and 9 of the tab and the circumference of the blank 5. Most importantly, however, a tab of metal strip 15 is cut out to form an elongated opening. 23, shown here as a slot having parallel sides 24 and 25 and inner and outer curved ends 26 and 27. When considering the planar item of FIG. 1, it is seen that the longitudinal axis 23 of the elongated slot coincides with the longitudinal axis of the tab 6. The end 26 of the slot 20 lies radially a little further inward than the innermost parts of the grooves 21 and 22. It can also be expressed that the slot 23 extends so far inwardly that it will lie between the weakening lines 13 and 14 just within the point where they meet the grooves 21 and 22. The location of the outer 27 of the slot 23 is not so important as the location of the inner end 26 and located in a portion 6a of the tab 6 which is imprinted to facilitate the grip.

When a blank 20 has been punched and provided with lines of weakness and notes, the next step to form the cap of the invention is a printing process wherein the peripheral collar portion 3 of the flat blank 20 is pulled down relative to the center or top portion 2. The result of this is depicted in FIG. 4, 5 and 8. In forming or pulling the cap of the planar blank 20, the metal in the collar portion 3 becomes rather hard machined or co-dusted due to the increasing decrease of the diameter of the rounding 4 to the planar periphery 5 with the collar portion moving downward. What has not been emphasized so far is the fact that the metal in the part of the collar from which the tab is exiting is under a considerably greater pressure than in the rest of the collar. Considering that the collar has been thinned out and weakened in the weakening area before the drawing is to be performed, it can be understood that if an effective safety measure is not introduced, the effects of the 2_0 machining are more pronounced in the weakening area.

In the prior art caps, detrimental effects such as deformation, warping, lifting or overlapping of the weakening lines or various combinations of these effects occur, with the movement of the metal increasing towards the maximum at the free edge of the collar.

These effects are common on both sides of the tear-off tab, though not necessarily to the same extent. This condition has given rise to unforeseen, disparate phenomena in the tear. As a rule, excessive resistance to tearing will occur, but the opposite can also occur.

Looking at FIG. 4 and 8, it will be understood how the elongated aperture or slot 23 serves to solve the previous problems. This is illustrated graphically by the shape assumed by the slot 23 in FIG. 4 and 8, compared to its original shape in the blank of FIG. 1. It will be seen that the sidewalls 31 and 32 of the slit have yielded to the pressure created in the collar, especially in the portion from which the tab extends, at the opening 3q of the collar from the planar state. Where the pressure is applied, it is illustrated that the top end of the slot at 30, as seen in FIG. 4, is closed pointedly instead of being rounded as seen at 26 in FIG. 1. Continuing down from there, the slit narrows as its sides 31 and 32 35 have been moved in towards each other down through the neck 7 of the tab to about the location 7a, where the tab 7 0 142022 bends outward. Returning to FIG. 4, it is seen that the top 30 of the slit is substantially above a horizontal line through the lower ends of the weakening lines. In the beginning, there is an open slot located directly opposite the 5 site where notes 21 and 22 are closed, and also directly opposite the location where the lines of weakness 28 and 29 begin. The fact that this slot has been narrowed graphically shows that the pressure in the collar at these locations is relieved by the sides of the slot being pressed together.

10 Although the parts of the collar which have been diluted by the weakening are less able to withstand the deforming forces produced by the pressure in the collar than the weakened part, the weakened parts are nevertheless capable of to withstand these forces to a greater extent than the sidewalls of the slit. Before the lines of weakening change into shape to such an extent that there is some significant change in the tear properties, the forces are transferred to and act on the walls of the slit, to a certain extent closing it.

20 As the slot 23 extends down the tear tab to the place 35 which, as seen in FIG. 5, located well beyond the bending line 7a, a further relief of the pressures occurs at the lower end of the weakening lines. This occurs because the increased length of the slot past the pressure position enables the sides of the slot to be more easily bent inward. Fortunately, the downward slopes of the slit do not have any detrimental effect on the flap and may actually improve the grip of the flap, but for this to be substantially achieved, it is advisable to extend the slider downwards, as shown in FIG. 10 and 11. The removal of the barrier against the sides of the slit closer together gives more space for the tear-off metal of the tear, at least at part 7, to flow away from the end of the weakening lines, and consequently provides better protection against a closure or failure. 35 has another unfortunate impact on these lines of weakness.

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Although the metal throughout the collar is subjected to considerable pressure by forming the collar 3 from the planar blank to the cylindrical form, it has been found in graphic studies made in connection with the invention that the printing is not so hard in the remainder. of the collar 3, as it is in the narrow portion thereof, from which the tear tab 6 exits.

The extension of the tab from part of the collar seems to impede such a flow of metal in this part of the collar which would to some extent relieve the pressures. Apparently, in the absence of an oblong opening or slit 23 in the portion of the collar which lies between the weakening lines 13 and 14, from which the tab 6 extends, the pressure also has a reactive effect causing disturbance or blocking of the weakening lines at the sites. 28 and 29, FIG. 4, where the weakening lines extend into the closed ends of the grooves 21 and 22.

Thus, it is this different flow path for the metal in the part within the lines of weakness, as opposed to the conditions outside the lines of weakness, that appear to have spring-2q the difficulty of the prior art. However, this relationship, just pointed out and shown by the shape that the slit 23 assumes when the workpiece is bowl-shaped, is taken into account, or it could be said that the effect is reversed by the sides of the slit approaching each other instead of The 25 lines of weakness are affected. This does not affect the strength of tab 6 needed when pulling it to break the lines of weakening and tear off the strip strip 15. In the face of the known attempts to solve the problem, the solution according to the invention is a real 3Q solution which is not accompanied by disadvantages.

In the following, the condition of the cap is explained after it is placed in place on the end of the bottle by pressing or otherwise, see FIG. 6, 7 and 9. The cap 1, fig. 4 has been provided with a suitable seal or gasket 40; 5, which as shown in FIG. 7 ends against the bottle bead 51, having been deformed and spread over the bead at the attachment. To secure the cap, a further reduction of the diameter of the previously formed collar is required. This reduction will also normally occur stepwise 5 in annular zones, as the collar of the cap will be pulled under the bead 51 and will have its lower portion positioned against the portion of the bottleneck located below the bead. With bead and neck as shown in fig. 6 and 7, the bead 51 has a sloping bottom surface 52 which extends into the bottleneck 50, 10 which is shown here to be substantially cylindrical. It should be noted that although the bead and bottle neck shown are intended to illustrate a form common in the non-alcoholic beverage and beer bottle industry, the cap of the invention can be satisfactorily applied to a plurality of other beads.

In placing the cap on the bead, a portion 45 of the cap collar is inclined inwardly beneath and toward the face 52 of the bead, while the remaining portion 46 of the collar is compressed most, being formed against the bottleneck 50.

The inward shaping of the portions 45 and 46 of the collar 3, including the tear portion 7 of the tear tab, of which a strip 47 inclines in the same manner as the portion 45, is best achieved by using rollers which progressively move the metal inwardly. This further reduces the radius of the inner molded parts, thereby affecting the metal in addition to the pressure applied in forming the collar 3. This treatment can be rather harsh and, as has been pointed out above, the result may be dependent of such conditions as the setting of the front rollers and the variations in the glass surface and the bottleneck, which are often encountered. It is readily understood that in the prior art it may have been possible to construct a cap that will be satisfactory until this fastening process. It has been more difficult to determine what would happen at the fastening itself, and thus what the final state would be at the removal of the cap by gripping the tear tab and tearing along the tear lines.

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Considered in FIG. 6 and 9, however, it will be seen that the elongated aperture or slot in the tab introduced by the present invention mitigates the interfering variations in the size of the pull needed to begin and continue tearing. of the stripping strip. These figures show that the elongated opening or slot in the tab has been further closed.

Its upper end 48 is a portion of the portion 47 of the surface 47 which is at the height of the cap portion 45 lying obliquely below the bottom surface 52 of the bottle bead. The upper end 48, which has almost become a point, is far enough below the lower end of the gasket 40, see FIG. 7 so that there is no weakening of the density against pressure.

The portion of the groove extending downwardly from the end 48, 15 narrows to a slit which continues downwardly to the site 49 below the free edge of the claim 5. Then, the slit opens with divergent sides 42 and 43 to the outermost end 44, approximately retaining its original width.

The manner in which the slot and tab are further reduced in width by the application of the cap to the bottle bead provides a graphic illustration of the manner in which the tension of the collar resulting from the attachment is absorbed into the slot, thereby the weakening lines, and especially their lower ends 28 and 29, are protected against deformation or closure sufficiently to substantially interfere with the tear-off operation.

The shape of the slot also illustrates the way in which the forces act through the portion 7 of the tear tab. As can be seen, these forces act to close the slot to a location slightly below the bead and further along the slanted sides 42 and 43 of the slot.

It will also be seen that the grooves 21 and 22 have been closed slightly more than in the non-attached form of the cap, as seen in FIG. 4. However, they are not fully closed, and the same applies to the part 41 of the slot, so that there is still security if the bead and the bottleneck should have sub-dimensions, so that a complete closure could take place, whereby 142022 11 o the tension would then be concentrated at the ends 28 and 29 of the weakening lines.

As will be seen from FIG. 6 and 7, all one has to do to remove the cap 1 from the bottle is to grasp the gripping portion 6a of the tab 6 and, moving it away from the bottle neck, begin tearing along the weakening lines at 28 and 29 and so as to continue tearing as the lines of weakening open in their upward direction, for which less force is required. An important factor in the described cap removal is that the pressure in the container will be released once the tear strip is free, a distance along the seal 40.

At some of the known closures that are removed by hand, the pressure is not released until the cap is completely broken, which may cause it to burst and injure the user.

In FIG. 10 and 11, a modified form of a slot designated as a whole by 6Q is shown. In FIG. 10, it is seen that the slot 60 has an inner end 61 and a pair of elongate sides 20 62 and 63, which corresponds to the slot 23 of FIG. 1 to 9.

However, the shape of the outer end of the slot 60 differs from the one shown previously, extending to a rounded portion 64 forming the center portion of the engraving embossing 6a.

When a cap formed by the blank of FIG. 10, being secured close to a bottle, the inner portion of the slot 60 will narrow to a narrow slot 65, from which sides 66 and 67 diverge toward the end portion 64. In this way, the rounded portion 64 serves to improve that grip. with which the consumer can grasp the tear-off tab.

FIG. 12, 13 and 14 illustrate application of the invention to a cap provided with weakening lines on its outer surface b. Blank 70 is essentially the same as Blank 20 of FIG. 1, the only difference being that the collar 73 is pulled downwardly from the circular top portion 72 of the rounding 74 in such a way that the weakening lines 75 and 76 extend into the metal from the outside rather than from the inside of it. bowl-shaped item. The weakening lines may extend in different directions, e.g.

they may be curved inward toward each other in convex curves, or they may be straight and diverging or converging as they extend over the blank from the tear tab, but for convenience, the lines of weakening 75 and 76 are shown parallel to the blank. It has been found that this kind of weakening is quite satisfactory in removing a cap made in accordance with the invention.

In FIG. 14, the weakening lines 75 and 76 have 15 short portions 13a and 14a extending down the collar, defining the tear portion 15a of the tear tab. Parts 13a and 14a end at 28a and 29a, adjacent to the location where the grooves 21a and 22a form closed slots.

In the known caps, which are formed with outside 20 weakening lines but lacking the extended opening or slit according to the invention, the difficulties encountered in closing the lines of weakening at 28a and 29a are only slightly different from the difficulties encountered by you come across when the lines of weakness are inside. The solution 25 is also obtained here by inserting an oblong opening 23a in the tear-off strip 15a and the part 6, as described in connection with FIG. 1-11. Here, too, the solution is seen graphically at the closure of the upper end 30a of the opening or slot 23a and the closure of its sides 31a and 32a. The rest of the tear tab 6, namely the neck portion 7, the bending line 7a and the gripper 6a at the end of the tear tab, need not be different from the previous shapes as illustrated and labeled with the same reference numerals.