MXPA97002651A

MXPA97002651A - Tops for containment

Info

Publication number: MXPA97002651A
Application number: MXPA/A/1997/002651A
Authority: MX
Inventors: Dudley Haaser James
Original assignee: Carnaud/Metalbox Plc
Priority date: 1994-10-12
Filing date: 1997-04-11
Publication date: 1997-06-01

Abstract

The present invention relates to a method for forming a weakening line (23) comprising brittle bridges (44) and alternating slits (42) in a tubular plastic edge portion (18) of a cover, with a formation (20) which is hingedly connected to the edge portion and extending from there upwardly and inwardly for the clutch with a complementary formation (54) of a container to which the cap is adjusted, and the bridges and slits being formed by cutting in the portion of edge from the outside of the lid at a location that is in radial alignment with the articulated formation and at the same time when the articulated formation clutches the inner surface of the edge portion, characterized by the cutting to form the bridges ( 44) and slits (42) is made in a location where the articulated formation (20) and the inner surface of the edge portion (18) are in contact with one another. with another, and in the slits is continued from side to side of the thickness of the portion of edge and partially towards the formation articulates

Description

"CONTAINER COVERS" This invention relates to covers for packaging containers, in particular, but not exclusively, to obvious violation covers for such containers. It is well known to provide a lid with an evident violation ability to form the tubular edge of the lid with a weakening line in order to define a marginal edge portion free of the edge as a safety band or ring. In some covers the safety ring has a fast clutch formation, which allows it to make a closing clutch with a complementary formation of the container, so that when the cover is partially removed or completely separated along the line of weakening, leaving the safety ring either leaving it behind the container or subject to the lid but able to clearly indicate that the lid has been operated. The rapid clutch formation can be a continuous ring, or it can be formed of peripherally disposed, movable projections independently. When formed in plastic material, the weakening line can be provided by a simple peripheral groove that leaves a residual thickness of plastic material, which is capable of tearing when the lid is first opened. However, more commonly, the weakening line has the form of several (for example, ten) fragile bridges of small area in cross section that are spaced around the lid and separated by slits in which the plastic material of the Shore is completely separated from side to side of its thickness. Commonly two alternative routes are used for the formation of the weakening line on a plastic bank. In a route the weakening line is a molding configuration of the shore, which is formed when the shore itself is molded. However, the molding of the weakening line often requires complicated and delicate tool parts that are expensive and of exposed use; in addition, the restriction to the flow of the polymer presented by the residual plastics materials (e.g., bridges) can create polymer underfeeding within the part of the cap that is downstream thereof in the direction of polymer flow. The second possible route to form the weakening line avoids the particular inconveniences of the first route, which are mentioned in the previous paragraph. In this additional route the weakening line is formed after the cap has been molded, usually by means of a partially circular knife (or succession of partially circular knives) to which the cap is presented. In this second way to form a line of weakening, if the weakening line is of the type that has separate bridges and clefts that separate the bridges, the knife is required to penetrate just through the wall of the lid edge to form the slits, and until now the practice has been to hold the edge internally by means of a roller or other supporting member that is inserted therein. Normally, the support member has been made of a material; for example, rubber, with which the knife can be contacted without being dull, or alternatively the scissors action has been installed to cooperate with the knife; however, in each case, contact with the knife causes degradation and use, and the support member and / or the knife have required a relatively frequent replacement or adjustment. Furthermore, in those safety rings that have a rapid clutch formation in the form of a continuous flexible ring or a series of individually mounted flexible elements, which are (are) attached around the lower free flange of the safety ring and thence extending (in) upwardly and inwardly in a resilient manner for the clutch with the container, the support member has normally been located so far at a sufficient height above the lower edge of the edge of the container. cover to ensure that it can reliably avoid contact with, and the possible damage to, the formation of the fast clutch, insofar as this (the support member) is inserted or removed from the cover or during its operation to hold the edge of the cover. This has imposed a limit less than the length of the line under the line of weakness, and it is necessary to locate the line of weakness at an oak distance from the free edge of the bank, which is somewhat higher at the height of the formation. of quick clutch inside the lid. Accordingly, the bank has been developed to extend a substantial distance below the weakening line, often resulting in an increased cost of material not only for the cap itself but also for the container for which it is designed the lid. The position of the free flange of the rapid clutch formation within the edge is also subject to limitation, since it has to be located below the line of weakening. US Patent Specification No. 5145078 describes a method for cutting a weakening line formed by alternating slots and bridges, in which the dimensional limitations mentioned in the preceding paragraph no longer occur because the rapid clutch formation extends from ascending way at least as far as the weakening line. The way of cutting is not discussed in detail, but in Column 4, lines 29 to 36 the formation of stops on the outer surfaces of the fast clutch formation is described, it is to keep the latter away from the tool by which they are cut. the clefts and bridges of the weakening line. Accordingly, it should be noted particularly that in US 5145078 the formation of the quick clutch engages, during cutting, with the edge of the cover outside it, but at the actual cutting location this is maintained at a space on the edge of the cover. the lid and so it does not hold from the inside. EP-A-0086970 (FIG. 6), FR-A-2528393 and US-A-4478343 disclose additional evident, plastic violation bands, which have fast clutch formations extending upwardly beyond the lines of weakening. However, none of these documents describes or shows the formation of the weakening line. It is an object of the present invention to avoid the drawbacks of the above-mentioned rape cover purposes, and according to one aspect thereof the invention provides a method for forming a line of weakness comprising bridges and alternate grooves in a portion of tubular plastic edge ie a lid, there being a formation connected in an articulated manner to the edge portion and extending from there upwardly and inwardly for the clutch with a complementary formation of a container to which the lid fits; and bridges and slits are formed by cutting the edge portion from the outside of the cap at a location that is in radial alignment with the articulated formation and at the same time when the clutch is engaged with the inner surface of the edge portion , characterized in that the cutting to form the bridges and slits is done in a place where the The articulated formation and the inner surface of the edge portion are in contact with each other, and in the slits the thickness of the edge portion is continued side by side and partially towards the articulated formation. Normally, in carrying out the invention, the bridges and slits are formed by knife means embraced with the edge portion external to the lid while the lid is restricted from lateral movement away from the knife means by the clutch with the surface interior of the articulated training.

In an installation such as that specified in the previous paragraph, the inner surface of the formation is preferably engaged by a roller having a projection by means of which the cover is restricted from axial movement by the clutch with the free flange of the articulated forging. In the application of the invention of the apparent flap covers as described above, the formation will normally be a rapid clutch formation which is attached to the edge of the lid around the lower free flange of the flap, and is adapted to clutch by under a protrusion of the container on its own free flange. BRIEF DESCRIPTION OF THE DRAWINGS The embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a cover of the type with which the invention can be used, in relation to a container to which the top; Figure 2 shows a known method for forming the weakening line in the lid of Figure i; Figure 3 shows the formation of the weakening line by a first method according to the present invention; Figure 4 shows the lid after the formation of the weakening line according to Figure 3; Figure 5 is a view corresponding to Figure 3 and illustrating a second method according to the invention; Figure 6 is a central vertical sectional view of a first apparatus capable of carrying out the present invention; Figure 7 is a view of part of the apparatus of Figure 6 seen from above in section VII-VII of Figure 6; and Figure 8 shows a knife support forming part of a second apparatus capable of carrying out the present invention, as seen from above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 in conjunction with FIG. 2, there is shown a plastic annular member 8 which forms the free terminal flange of the tubular edge 11 of a lid 10 to the PT vacuum (pressing, twisting) ) for a container 12 of a food product. The lid is usually made of metal; it has a metal sheet pressed metallic body, and screw threads (not shown) formed within its edge portion for the clutch with complementary screw threads 16 in the container.

The metal free rim of the lid is formed as an inward curvature 14 by which the plastic annular member is firmly held in a hook portion 1 (Fig. 2) that extends around its upper edge. In addition to the hook portion the annular member has a cylindrical central portion 18 substantially aligned with the edge portion (not referred to) of the metal body, and a rapid clutch formation in the form of a frustoconical ring turned inwardly 20 which it is fastened around an articulated line 22 towards the lower part of the central portion (and according to the above, of the lid as a whole) and from there it extends upwards and inwards toward a rim: -free free 23 The quick clutch ring 20 can be either continuous or can be formed of individually movable segments. Attaching it to the central portion in the hinge 22 allows it to be easily flexed for application to a container (not shown). The quick clutch ring 20 flexes outwardly from the molded position shown when the lid is being forced onto the container during capping, and thereafter resiliently closes back to its molded position where it can be clutched under a complementary rim. (figure 1) in the container. The annular member 8 is then able to provide its evident violation function required for the cap, and for that purpose it has a line of weakness 24 formed around its central portion 18 as a peripheral groove extending over a number of integral bridges spaced apart and brittle 44. The bridges are separated by slits or openings 42 in which the central portion is completely separated from side to side of its thickness. As is well known for the caps of the type shown, if any attempt is made to unscrew the lid for removal from the container 12, the resulting axial movement of the lid will cause the quick clutch ring to clutch with the edge of the container 54. An additional unscrewing movement then causes the bridges 44 are broken, thereby leaving the portion of the annular member 8 below the bridges that remain in the container while the lid is removed. It is then difficult or impossible for a person who violates it, to close the container again and reinstall the annular member 8, in particular its bridges 44, in such a way as to be detected. A particular feature of the cap of Figure 2 is that the weakening line 23 is located above the transverse plane of the cap that includes the free inner flange 23 of the quick clutch ring.

This configuration is inherent in the methods that have been used so far to form the weakening line by a cutting operation carried out after molding. For the purposes of this description the axial distance by which the weakening line is separated from the free ridge 23 is denoted by "X" in Figure 2. Referring now to Figure 2, in a known method for forming the weakening line 24 the bridges 44 and the slits 42 are created by a static knife 32 in the form of a toothed blade of thin metal against which the cover is rotated without slipping. Generally the knife is partially circular ^ having its peripheral cutting flange 34 recessed in separate notches 36 by which bridges 44 are formed. The teeth formed between the notches are denoted by the reference numeral 35. The knife is held and held by a knife. member ie support 60, of the cylindrical periphery 62 of which provides a limit stop to the penetration of the knife into the annular member 8. Internally, the annular member 8 is supported by the clutch of the cylindrical periphery 64 of a grooved support roller 66 the inner surface of the central portion 18 being above and below a peripheral groove 68 that is formed in the roller. The groove is rectangular in shape, and has a downwardly facing upper face 70. During the cutting operation the ring 8 is pressed between the support member 60 on its outside and the support roller 66 on its inside. The lid: 0 as a whole is consequently restricted from lateral movement, and in addition it causes the upper face 71 of the knife to cooperate with the upper face 70 of the groove 68 to form the weakening line by the scissor action. It will be understood from the foregoing that the method used to form the weakening line requires that the support roller 66 align transversely with the knife 32, that is, it must be axially overlapping the knife with the knife. However, the roller should be located above the quick clutch ring 20 in a sufficient space to ensure that the roller can not engage with, and possibly damage to, the quick clutch ring when it is moving to and from the operating position. shown and during the operation to form the weakening line. The margin of safety and the overlap of the knife with the roller together form the distance: X by which the line of weakness is located axially above the free flange 23 of the quick clutch ring. However, for many containers this location of the axially weakening line above the free flange of the quick clutch ring requires an undesirable and costly elongation of the neck of the container to accommodate the additional height involved. From another point of view, it imposes a limitation on the height "H" of the quick clutch ring that can be used with the same neck finish of the container. Figure 3 shows how the method for forming the weakening line can be modified to oppose this difficulty in accordance with the present invention. In Fig. 3, the same numerical references as before are used to indicate the same or equivalent characteristics. The cover 10 is still as shown in Figure 1, although with dimensional changes made to the annular member 8. Referring now to Figure 3, instead of directly engaging the inner face of the central portion 18 of the annular member 8, in accordance with the teachings of the invention the support roller 66 now supports the central portion 18 indirectly, acting through the quick clutch ring 20 which bends outwardly around the hinge line 22 so as to be in face-to-face contact with the central portion. The knife 32 is again aligned transversely with the support roller. During the formation of the weakening line 24 in the central portion the knife can, as shown and indicated in Figure 4 by partial cutting 95, cutting the outer surface of the quick clutch ring, but the penetration depth is small and is not sufficient to destroy the capacity of the quick clutch ring to carry out its required function to break the bridges when the lid is opened. From the previous paragraph it will be noted that in relation to the cap the weakening line 24 is aligned transversely with the fast clutch ring 20.; to put it another way, from its clamping on the articulation line 22 the rapid clutch ring extends, axially to the lid, beyond the line of weakness to its own terminal free edge 23. There are several advantages of this installation over those described in relation to Figure 2; i.e. (1) the support roller no longer has a groove 68, but instead has a simple cylindrical periphery that is available to provide support to the central portion in direct alignment with the knife; (2) the vertical position of the knife in relation to the support roll 66 is no longer critical, because no scissor action is involved; (3) the vertical position of the knife in relation to the annular member can be adjusted within wide limits because it no longer has to be above the free flange 23 of the quick clutch ring; and (3) po. the same reason the vertical length of the fast clutch ring can vary within wide limits to suit the finish of the container to which the lid is to be adjusted. Figure 5 illustrates a second method for carrying out the cutting operation on the lid 10, in which the support roller 66 engages the free flange 23 of the quick clutch ring 20 while the cutting takes place. The clutch occurs in a horizontal projection facing downwards 72 of a peripheral groove 73 of the support roller, in which the quick clutch ring is accommodated. It will be understood that by virtue of this clutch, the support roller constrains the top of the vertical movement at the cutting location. The meaning of this will become apparent later. In the embodiments described above with reference to Figures 3 to 5, the manner in which the lid 10, the support member 60 with the knife 32, and the support roller 66 are led to a clutch operative with each other, not it forms part of the present invention and therefore is only briefly described below. In a preferred installation, the support member and the knife are located on the periphery of a static and substantially circular central turret, and the support roller is part of a planetary roller assembly which is one of several identical assemblies that constrict and direct to move around a fixed circular path concentric with the turret. The constant take-up gears of the turret and each roller assembly direct the support rollers 66 to rotate at a predetermined speed around their axes so that rolling contact occurs only between the support member 60 and the annular member 8. as the lid passes the knife. A machine generally installed as described in the previous paragraph and capable of easy adaptation for operation in accordance with the present invention is particularly described with reference to the drawings (Figures 1 to 4) of European Patent Publication No. EP. 0533633 (Italcaps S.p.A. - reference of Agents 4499). That disclosure is hereby reproduced in this specification for reference, but its figures 2 and 3 are reproduced as figures 6 and 7 of this application when they are modified in an appropriate manner to incorporate the modality of figures 3 and 4 of this application.

Referring now to Figures 6 and 7, the non-rotating central turret, now referenced 74, is located on a central non-rotating shaft 76. Two of the planetary roller assemblies are shown in Figure 6 and are denoted 78. They are supported on the periphery of a wheel 80 which is mounted for free rotation on the axis 76 under the turret. The teeth of the gear 82 at its periphery are able to engage with a driven gear (not shown) to rotate the wheel with a predetermined speed and direction. As the wheel 80 rotates each planetary roller assembly 78 is individually driven to rotate by geared gears 84, 86 in the turret 74 and the roller assembly. The position of the gear clutch is aligned vertically with the cutting location, thus ensuring that no slippage occurs that could unmatch the quality of the line of weakness created in the cover. Figure 7 shows five of the roller assemblies 78 in a segment of the wheel 80 within which the cutting operation takes place. It is understood that the wheel moves in the clockwise direction in a circular path, generally from left to right, as indicated by arrow A. According to the above the roller ensaublajes rotate at the same speed - 1 ! peripheral in the clockwise direction. In Figure 7 the cutting edge 34 of the knife 32 is visible, its teeth 35 and notches 36 forming, respectively, the slits 42 and the bridges 44 of the weakening lines on the covers 10 that are carried after this. Upstream of the knife in the direction of movement of the wheel 80, the turret 74 has a cam face 88 by means of which the lids are individually placed on the roller assemblies and carried along them moving progressively outwards and towards the required displacement position in their respective roller assemblies for the clutch by the knife flange 32. As indicated in Figures 3 and 5, their annular members 8 are then depressed and located in the lateral direction between the turret. on the outside of the lid and the soporie roller 66 inside the lid. The vertical restriction for the lid during this time is provided by an overlay flange 90 (Figure 6) carried from the turret. In a modification of the apparatus of which part is shown in Figure 5, the tab 90 is omitted. The vertical restriction for a cover 10 during cutting is provided entirely by the projection 70 that faces the previously mentioned ab.

Figure 5 shows, in dotted line, the position of the support roller 66 and the fast clutch band 20 while the support roller and the cover 10 move in relation to each other before cutting, as previously described. A further relative approach movement of the support roller to the central portion 18 of the lid from that position will create some axial compression in the band 20. Applicants have found this beneficial in obtaining an accurate and reliable cut. The knife 32 of the apparatus shown in Figures 6 and 7 is mounted within the circular location of the roller assemblies 78, and according to the foregoing, its cutting edge 34 is generally convex. This relatively inaccessible position makes it difficult to adjust the radial position of the knife during the operation of the machine, if necessary. Figure 8 shows the fastener "90 of the ring 32 of a modified machine The knife again has a cutting flange 34 with teeth 35 and notches 36, but is concave instead of convex as before.The fixed structure of the machine, corresponding to the turret 74 in Figures 6 and 7, extends radially outward beyond the roller assemblies 78 to support the knife in a position for the clutch of the lids radially out of the path of the roller assembly, instead of inside the trajectory as before. An associated cam face (not shown) corresponding to the cam face 88 but concave instead of convex, produces any required inward movement of the caps to their misplaced positions on the roller assemblies for cutting. A micrometric measurement 92 allows the position of the knife to be adjusted radially "on execution". A lever 94 is available to adjust the knife's altitude in the horizontal plane. For the caps of which the quick clutch ring is discontinuous, it is preferred that the interruptions in the ring should have a small peripheral length so that the rear support provided by the quick clutch ring for the cutting operation is still substantially uniform around the lid. The invention is not limited in application to the tamper evident PT caps as is particularly described, but can have a wide application in caps of which at least part of the tubular edge is made of plastic material. The invention thus has application on lids that are substantially or completely of plastic material. Also, although it is basically conceived to form lines of weakness that define the safety bands of the evident violation caps and which according to the foregoing are visible from outside the cap, the invention can be used to form lines of weakness with others. purposes, taking into account that a clutch formation of a container is available inside the cover in transverse alignment with the location of the weakening line.

Claims

NOVELTY OF THE INVENTION Having described the present invention is considered as a novelty and therefore the claim described in the following claims is claimed as property. A method for forming a weakening line (23) comprising brittle bridges (44) and alternating slits (42) in a tubular plastic edge portion? 18) of a cover, there being a formation (20) that connects articulated way to the edge portion and extending from there upwards and inwards to the clutch with complementary training (54) of a container to which the lid is flattened, and the bridges and slits formed by cutting the edge portion from the outside of the lid in a location that is in radial alignment with the articulated form and at the same time when the articulaca formation makes clutch with the inner surface of the edge portion, characterized in that the cut to form the bridges (44) and slits (42) is made in a location where the articulated formation (20) and the inner surface of the portion of edge (18) are in contact with each other, and in the slits is continued from side to side the thickness of the edge portion and partially towards the articulated formation. A method according to claim 1, characterized in that the bridges (44) and the slits (42) are formed by knife means (32) engaged with the edge portion (18) externally to the lid while the lid is restricts lateral movement away from the knife means by the clutch with the inner surface of the articulated formation (20). A method according to claim 2, characterized in that the inner surface of the articulated formation (20) is engaged by a roller (66) having a projection (72) by means of which the cover is restricted from the axial movement by the clutch with the free flange (23) of the articulated formation.