AU593442B2

AU593442B2 - Lid of sheet metal for cans

Info

Publication number: AU593442B2
Application number: AU16186/88A
Authority: AU
Inventors: Lutz Strube
Original assignee: Schmalback Lubeca AG
Current assignee: Ardagh Metal Packaging Germany GmbH
Priority date: 1987-05-15
Filing date: 1988-05-16
Publication date: 1990-02-08
Anticipated expiration: 2008-05-16
Also published as: EP0291095A2; DE3716382A1; AU1618688A; EP0291095A3; ZA883415B

Description

593442 COMMONWEALTH OF AUSTRALIA Patent Act 1952 CO M P LE T E S P E C I F I C A T ION

(ORIGINAL'

Class Int. Class Application Number I 43

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111111 I I I1 I t I1 III i Iodged Complete Specification Lodged Accepted Published Priorit,,t 15 May 1987 Related Art This document contnins the amendments allowed uidet Soeion 83 by the Supervising Ex,1nmin1r on and 1i corret for prhiag i

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I I Name of Applicant Address of Applicant Actual Inventor/s Address for Service SCIMALBACH-LUBSCA AG Postfach 3307, 3300 8raunschwoig, Federal. Repubio of GermanY Lu tz Strube t FBi RICE CO, Patent Attorneys, 28A Montague Street, BALMAIN 2041.

Complete Specification for the invention entitledt LID OF SHEET METAL FOR CANS The following statement is a full description of this invention including the best method of performig it known to us/rk- 4 -2- The invention relates to a lid of sheet metal for cans having the features of the preamble of claim 1.

Such lids are e.g. known from~ the DE-AS 21 46 452 or f rom the German Utility Model 75 34 780. It is of no importance for the present invention whether two independent openings, one of which being a vent and the other a pouring opening or only a single opening is prepared which undertakes both functions.

In the aforementioned publications two space~d openings of the saie or different diameter are prepared in the end panel ort a diameter. Each opening is prepared by a continuous punching line which has in the known case an interruption point, by means of which the punched out sheet metal element is permanently connected to the end 1 panel of the lid. This interruption point is at the same time designed as articulated point so that during opening *the sheet metal element can be folded or bent into the interior of the can under the action of a pressure from the outside.

There are a number of problems in such lids. In the production of the lid the Ounched out sheet metal elemen~t :oust be inwardly bent f rom the plane of the end panel of the lid around the articulated point so that the opening widt~h can be reduced relative to the diameter of the punched out sheet metal element by the deformation of the sheet inetal element and/or the opening edge, so that in the closing position of the sheet metal element in the area of the punching line there is a slight radial ovelapping of the edge of the sheet metal element and the opening edge. Due Io this the edge of the sheet metal element comes to rest under the edge of the opening in the closirig position, Due to the necessity of the bending of the sheet metal element and due to the resiliency ability which may be different due to variations in the hardness in the starting sheet metal, the punched out sheet metal "3" element tends to remain in the closing position forming a gap in a slightly inclined position to the end panel of the lid. The resultant gap must be closed and sealed upon the application of the sealing composition. The sealing composition must furthermore be selected in such fashion that it keeps the same in the closing position also in the case of an unintentional pressure on the punched out sheet metal element and prevents a premature breaking in of the opening. Such loads may occur during handling and/or stacking of the can.

It is the object of the invention to further develop a lid with the features of the preamble of claim 1 so that S* the difficulties set forth are avoided in simple fashion.

This object is solved by the measures of claim 1.

S 15 If it is proceeded from a design of the lid, in which the punched out sheet metial element is permanently connected to the end panel of the lid via an interruption point of the punching line, a single welding spot is sufficient, as a rule, for each sheet metal element, which 20 is preferably disposed diametrally opposite to the interruption point of the punching line to attach the shev t metal element in firm abutment to the lower side of the edge of the punched opening. Due to this the position of the sheet metal element becomes independent in the closing position of any resiliency ability of the sheet metal and the variations of this resilicency ability. The result is that substantially more favourable and constant conditions ensue for the application of the sealing composition on the lowe; sido of the lid, so that the production is simplifed and made more reliable. There is also more independence in the selecton of the type of the sealing composition, because the same is mechanically relived in the closing position by the mechanical attachment of the punched out sheet metal element. At the same time a substantially greater safety against an

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i I I unintentional premature breaking open of the punched openings is achieved, because the attachment point keeps the sheet metal element mechanically sufficien-ly firmly to the edge of the punched opening to be able to receive the customary loads from the outside which may occur during stacking of the cans or during their handling.

Moreover a warranty closure is obtained due to the welding spot, which reliably reveals a previous opening of the receptacle.

In a design of the cover in which the punching line 0*r. is continuously formed and the punched out sheet metal element is completely removed from the end panel of the lid, two or more than two point-like attachment points may S0 be applied by welding which are distributed in the 0* 15 direction of circumference in the desired fashion. It is true that in the invention the design with interruption point in the area of the punching line, described at first is preferred.

The welding spot may be produced spot-like with 20 extremely small diameter. A diameter extension of 1/10 mm or only a few tenths of a mm are preferred.

The production may be effected by electron beam S welding or laser beam welding in a simple, quick and reliable fashion.

It is advantageous if the or each welding spot is completely covered by the sealing composition at least towards the interior of the can. A spot of sealing composition may also be applied from the outside in the area of the welding spot, which also Covers the welding 30 spot from the outside.

The invention is explained in more detail in the following by means of an example of embodiment and schematic drawings.

Fig. 1 shows a cross-section through a lid according to the invention.

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D nl 0 '0 ,"0 fti Fig. 2 shows a cut out on a larger scale of a cross-section through the area of the vent opening and Fig. 3 shows in similar representation as Fio- 2 a cross-section through the area of the pouring opening of the lid according to Fig. 1.

The lid 1 of sheet metal shown in Fig. 1 has a customary cross-sectional shape. The lid has a lid edge 2 into which a plastisol or the like is introduced as sealing composition 3 at the lower side. The edge of the lid is connected via the chuck wall 4 with an shock-absorbing grip 5, which reaches up to below the plane of the end panel 6 of the lid surrounded by the shock-absorbing grip.

On a diameter two spaced openi=gs are provided in the end panel of the lid which are in each case limited e.g.

Sby a circular punching line or a punching line with another contour. Each punched opening is hermatically sealed by the punched out sheet metal 7 or 8 in connection with an annular sealing composition 31 applied to the 20 lower side of the lid, which can be gathered from Fig. 4.

*In the represented example the punched openings have a different diameter. The punched opening 7 of larger S"diameter serves for pouring the content of the can, while the punched opening in the area of the sheet metal element 8 serves as a vent opening.

S* The lid 1 is hermetically connected to the edge of a can body e.g. via a customary double folding seam. The design of the lid edge and its connection to the can body can also be effected in a different fashion.

The punched out sheet metal element can be completely separated from the end panel 6 of the lid via a punching line. However, in the represented example the punching line has an interruption at a limited circumferential point so that a permanent web-like connection 11 remains between the punching element and the end panel 6 of the I .X

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4, 4 9 9 4 4 0 lid. This connecting web 11 forms at the same time an articulated line between end panel 6 of the, lid and the punched out sheet metal element about which the same can be pivoted into the interior of the can for the opening of the can in accordance with the arrows 12 or 13. When doing so the sealing composition 31 is either detached from the lower side of the end panel of the lid or sheared off in the area of the punching line.

The punched out sheet metal element 7 or 8 and the 10 associated marginal area of the punching openings are in each case subjected to a forming process as this is revealed still more clearly by Figs. 2 and 3. In Fig. 2 the area of the vent opening is shown and in Fig. 3 the \Area of the pouring opening. It can be gathered from 15 Figs. 2 and 3 that the opening margin comprises an annular area of noticeable radial width, which is in each case connected to the end panel 6 of the lid via a shoulder or 25 and has an annular, plane area 16 or 26 which is located above the end panel 6 of the lid, which limits by its 20 edge 17 or 27 extending along the punching line the respective opening. one recognizes in each case on the righthand side in Figs. 2 and 3 that the opening edge 17 or 27 has a web-like interruption at, 11. At this point the punched out sheet metal element is in each case permanetly connected to the end panel 6 of the lid. As can be seen from Fig. 1 these web-like areas 11 are on the same side of the associated opening. In the pouring opening this at~ea faces the centre of the lid, ws-ereas in the vent opening this area faces the edge of the lid. Each punched out sheet metal element is formed in such fashion that the annular outer area 20 or 29 cc.,!mes to rest in a plane between the plane of the end panel 6 of the lid anid the plane of the annular marginal. area 16 or 26. The web-like 4irticulated point 11 thus forms at the same time also a shoulder between the areas 16 and 20 or 26 and 29 being in -7.

different planes. The central area of the punched out sheet metal element is formed to a button-like area 19 or 289 rising beyond the plane of the annular marginal area 16 or 16 via which the opening pressure necessary for opening can be applied onto the punched out sheet metal element.

After the punching process the marginal area 16, 17 or 26, 27 of the punching opening and/or the punched out sheet metal element are subjected to a deformation which reduces the width of the punched opening with respect to E the diameter of the punched out sheet metal element so that the edge of the punched out sheet metal element slightly overlaps the marginal area of the punched opening at the inner side of the end panel of the lid as this can 15 be seen from Figs. 2 and 3. The mentioned different deformations can be carried out at the same time, namely all of them after the production of the punching line.

However, the deformation can also be carried out in different steps and partly before and partly after the 20 punching.

Prior to the application of the sealing composition according to Fig. 3 a single welding spot 21 or 30 is provided in the area of each punched opening in the respresented example in each case between the marginal 25 area 20 or 29 of the punched out sheet metal element and the marginal area 16 or 26 of the punched opening, namely diametrally opposite to the articulated area 11, in the shown example of embodiint also two or more than two welding spot or attachment points may be provided.

However, it appeared that in general a single attachment point is sufficient so that in the preferred example of emb(diment represented here only a single attachment point 21 or 30 is shown in each ca'e. The attachment point is o provided as a welding spot. It only has a very small dimension, preferably of only a few tenths of a mm, in particular in o .0 0 \i the order of about 1/10 mm. The welding spot is preferably produced by means of electron or laser beam welding. In the production of the welding point the punched out sheet metal element is kept in firm abutment against the lower side of the edge of the punched opening, namely overcoming the resiliency ability which is stored in the sheet metal sections due to the production processes.

The binding force of the attachment point is selected in such fashion that the holding force reliably exceeds t:o* the resiliency force in the sheet metal sections and is also larger than the possible outer loads of the punched I out sheet metal elements to be expected during stacking or Shandling of the cans. The holding or bonding force at the bonding points is, on the other hand, dimensioned in such Sfashion that it is lower than the opening forces to be applied on the punched out sheet metal elements for opening the can.

The lid may also only have a single punched opening which undertakes at the same time the vent function. The punched out sheet metal element may also be completely separated from the end panel of the lid and connected I f j f again to it by several attachment points. However the design shown in the Figs. with web-like articulated area 11 is clearly preferred over such a design.

It cat be seen from Fig. 3 that the welding spots are covered at the inside by the sealing composition 31. If required, a sealing composition spot may also be applied from the outside to the edge 17 or 27 in the area of the 3 welding points 21 or 30 to protect the welding spot against the influence of humidity or the like from the outside.

The figures described herein include those figures in German Federal Republic patent application P3716382.5 filed 15 May" 987.

Claims

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