AU620572B2 - Method and apparatus for the closing of a container - Google Patents

Description

PF/Mar/19/1981 U. lir II syv -I I OPI DATE 02/05/89 wo AOJP DATE 15/06/89 APPLN. ID 25528 88

PCT

PCT NUMBER PCT/SE88/00538 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 89/ 03344 7/28, 51/10 Al (43) Internat al lici nA D e April 1989 (20.04.89) (21) International Application Number: PCT/SE88/00538 (81) De a te ta T ropn p AU, BE (European patent), CH (European patent), DE (Euro- (22) International Filing Date: 14 October 1988 (14.10.88) pean patent), DK, FI, FR (European patent), GB (European patent), IT (European patent), JP, KR, LU (European patent), NL (European patent), NO, SE (31) Priority Application Number: 8704048-1 (European patent), US.

(32) Priority Date: 15 October 1987 (15.10.87) Published (33) Priority Country: SE With international search report.

In English translation (filed in Swedish).

(71) Applicant (for all designated States except US): PLM AB [SE/SE]; Djaknegatan 16, S-201 80 Malma (SE).

(72) Inventoi, id Inventor/Applicant (for US only) INGEMANN, Ole [DK/DK]; R6nnebaervaenget 8, DK-5856 Ryslinge

(DK).

(74) Agent: MAGNUSSON, Gustav, Gustav Magnusson AB, Magnupatent, Post Box 6207, S-200 11 Malm6

(SE).

(54) Title: METHOD AND APPARATUS FOR THE CLOSING OF A CONTAINER (57) Abstract The invention relates to a method and a device for the 63 J 26 7, 61 4 47 8,16760 sealing of a container (10) by means of a wafer The tainer comprises one or more joining means (14, 16) which are 47 7 adapted so that by a joint e.g. a welding joint, they are 46' connected in a leakproof manner, to the wafer in an edge 37 0 zone (21) of the same. The wafer is held against a contact sur- .37 face (32) of a retaining means so as to be moved by the same 4 72 until it rests in its edge zone (21) against anyone of the joining 42 means (14, 16). Whilst the contact with the retaining means is_ maintained, the wafer is connected by a fixing means (50) in /c 3 its edge zone in a leakproof manner to anyone of the joining means through the fixing means supplying energy to the edge L- 22 4 zone so that a joint (12 is formed. The invention makes it 4 14 possible to fix in a leakproof manner a previously cut wafer 17 to the opening part of a container. The sealing can be done 29 3 even on containers with hot contents, since in certain embodi- 20 7 ments the retaining means is cooled with the help of cooling ducts The retaining means cools the wafer and prevents it from being deformed owing to the rise in temperature. 9 which the proximity to hot contents otherwise would bring ,174c 173 about. 8s 82/ Y c SWO 89/03344 PCT/SE88/00538 Method and Apparatus for the Closing of a Container The present invention relates to a method and to a device for the sealing of a container in accordance with the preambles of the independent claims 1 and A need frequently arises for the sealing of a container, e.g. a container of plastic material, by way of a laminate whose shape has been adapted to the shape of the opening part, already prior to the placing of the laminate on, or into, the opening part. It has been known to seal containers with the aid of a foil of multilayer material, where the foil, after the container has been sealed, is trimmed in order to remove the parts of the foil projecting outside the edge of the container opening.

One problem which is encountered on sealing of containers by means of foils, and especially by means of multilayer foils, is that on heating the foil it tends to get deformed because of curling. Since the foil as a rule is relatively thin, it assumes ambient temperature after a short time or is heated rapidly on being subjected to thermal radiation. Such an environment exists for the foil when containers are to be sealed which are filled with warm or hot contents, and generally occurs on packaging foodstuffs. In certain applications, and especially when the foil is composed of layers of materials having different coefficients of linear expansion, the probler associated with the deformation of the foil is accentuated. W'hen the foil gets warm it will curl so that if on the foil, the layer with the greatest coefficient of linear expansion faces the container opening, the circumferential outer edge of the foil will be raised, whereas on opposite placing of the layer the outer edge is displaced iownwards.

The aforementioned deformations, as a rule. can be overcome if a foil in the form of a band is stretched over one or more containers and is fixed to the opening part of the respective container, in thct the foil during sealing is kept stretched by mechanical means which counteract the tendency of the foil to curl. W.'hen the foil has thus K' o 1 1

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1 1 1 WO 89/03344 PCT/SE88/00538 2 been fixed, any projecting parts are cut off the respective container. However, in cases where the foil consisting of several lIyers is cut to wafers, each of a shape corresponding to the shape of the opening part of the container, prior to being fixed to the opening part of the container, it is not possible to stretch the foil by mechanical means, e.g. between its edges, so as to prevent the undesirable deformation (curling up) which on sealing of e.g.

hot-filled containers entails only too often the occurrence of leaky closures.

In accordance with the present invention the aforementioned proble" of sealing a container by means of a foil cut in advance, which forr: a wafer of a shape adapted to the shape of the opening part cf tlhc container which is to be sealed, is eliminated.

This is achieved by means of a method and a device which are specified in the characterizing parts of claim 1 and claim respectively., In a preferred embodiment of the invention the sealing of the container takes place while an outer sealing means, in leakproof manner, delimits F space which accomodates the ecdg zone and the storage space of the container, the space bein- evecupatd an.. maintaining a vacuum, the edge zone of the wafer beinc fixcZ ir.

leakproof manner to the joining means.

The invention also comprises embodiments where for the formation of the joint between the wafer and the actual joining means, a fixin. i agent (bonding layer) is applied to the underside of the wafer.

exclusively to the bonding surface of the opening part or to the underside of the wafer as well as to the bonding surface of the opening part. It is obvious that in certain applications such an

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PJ) :j Ii WO 89/03344 PCT/SE88/00538 agent is applied exclusively to the bonding surface of the openinc part. It is obvious that in certain appliations the agent is coated exclusively onto the underside of the outer edge zone of the wafer.

In the dependent claims are given furtehr appropriate embodiments of the invention.

The invention is described in more detail in connection with a number of figures, wherein Fig. 1 shows a section through a wafer, Figs 2-4 are axial sectional views of a device for the sealing of a container showing successive sealing stages, and Fig. 5 shows the retaining means of the device seen from below.

In Fig. 1 is to be found a wafer 20 of a shape adapted to the shape of the joining means, e.g. a flange, of the opening part of the container which is to be sealed by means of the wafer. In the embodiment shown in Fig. 1 the wafer comprises two layers 2. T! upper side of the wafer has the reference number 23 and its undersid: the reference number 22. The wafer 20 is defined by an outer eccE zone 21 closed in the peripheral direction of the wafer, as a ruic adjoining the edge or edges of the wafer. In the embodiment shown, in Fig. 1 the upper layer consists of a metallic material, e.g. aluminium, and the lower layer of a plastic material. The lower layer in turn is coated with an adhesive layer 26, e.g. a glue layer. It wil be obvious, though, to those versed in the art, that in addition to the embodiment shown in Fig. 1, the invention is applicable to wafers made up of layers which deviate as to number and type fro. what has been specified above. In certain embodiments are include. e.g.

layers exclusively of metal foils or exclusively of plastic materirl whilst, as a rule, at least one layer of berrier material is alsc included.

o WO 89/03344 PCT/SE88/60538 4 In Figs. 2-4 is to be found a container 10 with a sealed bottom part 2G, a container wall 11 and an opening part 13. The opening part is provided with joining means 14, 16 to cooperate with outer sealinc, means 40 described further below and/or with fixing means 50 by which the wafer is fixed to the opening part of the container. The joining means in the embodiment of the container shown are in the form of an upper flange 14 and a shoulder 16 arranged underneath it, Reference numbers 15 and 17 respectively relate to an upper boundary surface on the flange and on the shoulder respectively. The container has a storage space 13 which in the figures is shown as filled with goods 19. The opening part 13 of the container rests on a supporting means 29 which sustains the container in connection with it beinz sealed. In the embodiment of the device in accordance with the invention shown, the wafer 20 is held (see e.g. Fig. 2) by a retaining means 30 shown in an embodiment with a lower part 34 and an upper part 36 and with an insulation 35 present between these two parts, ir the lower part are provided ducts 33 for adjustment of the tempereture. The lower part has a lower surface 32 which constitutes the contact surface for the wafer. The retaining means is provided with c duct 31 which is connected to a first source of vacuum 71 via a, generally, flexible pipelinc 31a. The duct is finished off by one c" more openings 31c (see Fig. 5) which are located in the contact surface 32 of the retaining means and which as a rule arc slacec.

centrally. The upper part 36 of the retaining means is connected c first guiding and transfer means 37 which is provided with one or more projections 3 directed away from the centre havinc a striking surface 39 facing downwards in the figure.

An outer sealing means 40 has a contact part 41 intended to be moveto and from a position wherein, according to the embodiment shown, the contact part rests with a sealing surface 49 against the openinpart 13 and, in particular, against the upper boundary surface lt cf the flange 14 of the opening part. The pressing surface 49 of the outer sealing means 40 is adapted to the shape and structure of tn,.

opening part 13 in the region where the -ressing surface co.p.ra:ez with the opening part, e.g. iadaptec to the upmr boundary surfac:.- .1 Sof thp flanue so that, on restino' acaint tha sar-e in a s!iistn.ti i r- ri WO 89/03344 PCT/SE88/00538 leakproof manner, it permits means 40 to form a delimited closed space 70, hereinafter referred to also as first space 70 (see Fi.

which accomodates the retaining means 30, the wafer 20 and also the storage space 18 of the container.

The sealing means 40 has an upper part 47, hereinafter as a rule referred to as a coupling plate 47, for the connection of the sealing.

means to a top plate 60. In the top plate as well as in the coupling plate spring mountings 61 and 48 respectively are provided which cooperate with springs 62 adapted to transfer the movement of the to:: plate to the coupling plate. The top plate is connected by a coupling means 51 via one or more coupling bolts 63 to a fixing means S0, finished off by a pressing surface 5G, which in the figure is cirected downwards, that is to say towards the edge zone 21 cf the w'afer.

The coupling bolts and the coupling means thus constitute the means of connection and transfer for the cooperation of the top plate with the fixing means 50. The fixing means is provided with heating means 52 which may be constituted e.g. of electric heating wires or ducts for a heating medium. An insulation 53 prevents heat transfer betwee;, the fixing means and the coupling means 51. The coupling means -1 is provided with one or more projections 54, directed towards ten cenre of the device with a striking surface 55, directed uopw-ar's in the figure, intended to cooperate with the striking surface e: cf th.projections 38 of the first guiding and transfer means 37.

Between the fixing means 50 with its coupling means 51 and the outer sealing means 40 a passage is formed, shown in the figures in an embodiment where it contitutes a gap 42, this passage connecting vir a duct 43 and a, gererally flexible, pipeline 43a connected thereto, the space 70 enclosed by the sealing means 40 to a second source of vacuum 72. It is obvious that in certain embodiments a correspondinc passage to the second source of vacuum 72 is obtained in that the F duct 43 opens out in a region close to the fixing means that ir to say in a region close to the openinc* part of the container, whereas in other embodiments the fixing means and/or its cou:linri Smeans 51 are provided with passages which connect the s:-ce 7" t uct 43 cnd/r the source of vacuurI. In ccrtcin cases t-o tw acts I' I 21, :Z are connected to a common source cf vacu::., WO 89/03344 PCT/SE88/00538 6 The coupling plate 47 of the outer delimiting means 1:u is proviaec with bearings 46 for bearing sleeves 45 which enclose the connecting bolts 63. The bearing sleeves are displaceable in the bearings 46.

Seals 44, preferably designed as 0-rings, are provided in the bearings 46 so as to prevent a passage of gas into the space 7C whic!' is delimited by the sealing means 40 when it rests against the opening part 13 of the container.

As a rule the device in accordance with the invention also includes a lower delimiting means 80 which is joined in a leakproof manner to the supporting means 29 so as to form a second closed space S2 whichl is delimited by the lower delimiting means and by the supporting means 29. Uhen the container 10 is supported by the supporting neans 29, at least the lower part of the container as a rule projects intu the second space 82 as a result of which the container, the supporting means and the lower delimiting means form the closed space.

Sealing means 81 fitted to the lower delimiting means and/or to the supporting means ensure that the delimiting means is joined in a leakproof manner to the supporting means 29 in c region enclosing the container 10. The lower delimiting means is provided with a passage 04 which via a connection 84a, e.g. a, generally flexible, pipe cr duct, connects to a third source of vacuum 73. In certain e-bocinorts the lower delimiting means is adapted so as to be movable in rclctic" to the supporting means 29 in order to make it possible to dis:-'lac the supporting means and the delimiting means fror one a.nother ir conjunction with the conveying of the container to and from the sealing station. In this manner an improved accessibility is also obtained to the region underneath the container 10 when it rests against the supporting means 29.

Valve elements 74e-c are provided in the conduits 31a, 43a, ,4a to the sources of vacuum 71,72,73. By means of control means, not shown in the figures, an individually controlled opening or closing of ths i connections between the sources of vacuur; and the ducts 21, 42 anc i respectively by means of the valve elements is mace possible.

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WO 89/03344 PCT/SE88/00538 In certain embodiments of the invention one single source of vacuur, common to all ducts is used or, as an alternative, the sources of vacuum are joined to one another by means of a conduit 75 indicatec by broken lines in Fig. 2.

In Fig. 5 is shown in detail an example of an embodiment of the contact surface 32 of the retaining means. In the example the surface is provided with grooves 31b which are connected to the opening 31c of the vacuum duct 31. These grooves are distributed over the contact surface 32 inside a closed boundary zone 32a located in the circumferential direction of the contact surface. !'hen the wafer rests against the contact surface, the grooves, owing to the connection c' the grooves to the source of vacuum, forr. vacuum ducts which ho!ld t.

wafer tightly on the retaining means Fig. 2 shows the wafer 20 resting against the retaining means 3C owing to the partial vacuum prevailing in the grooves 31b of the contact surface. Through the relative movement between the supportin: means 29 and the retaining means 30 along with other means cooperating with e retaininc means, the wafer 20 has been placcd in a position directly above the opening part 13 of the container l. wafer is kept at the desired temperature, as a rule a low temperature, by a mediur, which generally for the cooline of the lower 34 of the retaining means, passes through the ducts 33.

Cy driving means, not shown in the figures, the top plate 60 is move' downwards in the direction towards the container 10 (see Fig. t! retaining means 30 moving the wafer 2 until it rests against the shoulder 16 of the opening part. The outer sealing means 40 and the fixing means 50 with its coupling means 51 also follow the do.wnwvar movement. The sealing means in fact is moved down to rest against t:opening part 13 and, in the embodiment shown, to rest against the upper boundary surface 15 of the flanre The first space 70 whic' is now delimited by the sealing means 4C is cornected thercafter to the second source of vacuum 72 by means cf the duct '23. rcsl vacuum is created in the whole of the enclosed recion ,wic. als: includes the storag; space 1l of the container. TIhe vacuur entr.i'i

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WO 89/03344 PCT/SE88/00538 that air and/or other gases, which are present undernect. the wafer are sucked out from the space underneath it and pass between the edge zone 21 of the wafer and the opening part 13, as a rule the upper boundary surface 17 of the shoulder. The pressure in the first space 70 is adjusted as a rule to a value which is higher than the pressure which prevails in the grooves 31b of the retaining means 3:.

thus ensuring that the wafer is not detached from the retaining means.

In the embodiments comprising the lower delimitinr means 03 a reduction of the pressure generally takes place also in the secon' (lower) space 82 at the same time as the pressure in the first s:rc above the contents is reduce'. it is obvious thZ;t this simultaneous reduction of pressure is achieved through oDeninc cf t.

valves 74b, 74c in the pipeline or pipelines connected to the source of vacuum. The reduction of pressure in the lower space 2 is performed, when there is a danger that the pressure difference across the container wall might cause a deformation of the container.

The top plate GC thereafter is moved by its drivinc ne.ns furt,r downwards towards the container 1, (see Fi,. Since t'e soelinr means 40 already rests against the flange I 1 the bolts .1 an bearinc. sleeves 45 are displaced in the beerinzs w, it: sir:ultencous compression of the spring a2. In the course of t:-is ,c xi means 50 is moved to rest against the edge zone 21 of the wafer Ean; the latter is pressed by the pressing surface 56 of the fixing neans against the shoulder 16. The width of the edge zone 21 of the wafer, that is to say the width of the area of the wafer outside the contact surface 32 of the retaining means, is adapted to the rise in temper.ture occurring in the wafer material and the characteristics of the wafer material, so as to prevent the movement (curling) upwards cr downwards of the edge region from becoming so groat that the correct contact of the edge region with the shoulder mijght he jiopar-ize.

The fixing means is a6justed by then heatino means Cucr.s or electric heatinc wires, to a predetermined tereerature Cadapt to t'.c typc cf joint by means of \ic, the wafer is to be attac to t: container i, The tc; late, n so the fixing r.cian, 1rrc .ir.ti..

in thoir lower pcsiticn for a sufficiently. lone Cric: to l' w

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4'1 WO 89/03344 PCT/SE88/00538 j joint or joints 12 to be formed and the wafer be fixed to the container e.g. through the supply of the required amount of energy tr the connecting region. After the joints have been formed, the connection to the respective source of vacuum is cut off and the driving means for the top plate moves the latter in the direction away from the container (upwards in the figure). In an alternative embodiment of the invention the movement takes place in that the connection of the driving means to the top plate is interrupted anc the springs 62 move the top plate to the position shown in Fig. 3. Fy the driving means the top plate thereafter is moved to the position shown in Fig. 2, whereby the striking surfaces 39 and 55 of the projections 38 and 50, respectively, res, against each other, as result of which the projections 54 move the first guiding and transfer means 37, and consequently the retaining means 3C, in the direction away from the container 10. Through the relative movement between the supporting means 29 and the retaining means 3C along wit' means associated with the retaining means, the retaining means subsequently is given the opportunity of picking up a new wafer, whereupon the procedure described above is repeated.

The retainina means 30 has been shown in Fig. S in an erbociment where it has a mainly circular cross-section. It will be obvious to those versed in the art that the invention is acplicaHle to anr' arbitrary cross-section, and thus also to polygonal ones.

The invention has been described in connection with embodiments vhic' in the drawings illustrate how the wafer is fixed to the shoulder 1l of the container. It is self-evident that the invention likevwise car be applied to embodiments where the wafer is fixed to the upper bouncary surface of the flange 14. In this case it is ensured that the cortact part 41 of the sealing means 40 alternatively rests only against an upper outer part situated in the circumferential direction of ti'c container flange 14 or e.g. against the underside of the fiance or against the supporting means and thct the wafer 20 rests ecain t the flange 14, inside the sealing means 4C. The fixing me-.ns 5C wit its pressing surface 5 then presses the edge region 2i against thflange 1i. The flexibility in the wafer nateril mnaes it ocssi'-,.

in this emlbodiment of the invention too, for the air andeor to be suckCe out frcr the region cxisting und-rneatih wafer 2

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1 j at w ~o~ [I LK ~r i WO 89/03344 PCT/SE88/00538 As a rule it is desirable in case of the type of goods involved herein, that the free space between the goods (the liquid) and the wafer should be as small as possible. In applications where the goods are warm, that is to say at temperatures of approx. 60C, and especially if the temperature exceeds 75-800C, the heat effect of the goods upon the wafer is very strong. In such applications there is a risk of an undesirable curling taking place in the edge zone. .s is evident from the above, however, it is possible to adapt the lower part of the retaining means to the size of the wafer so that the part of the wafer which is radially outside the retaining means is subjected to very little expansion in the radial direction. a result the risk of such undesirable curling in the edce region is minimized.

In certain applications the wafer is ultrasonically welded to the opening part of the container by means of a sonotrode which constitutes the fixing means 50 and which supplies the recuirec energy to the fixing region in order to form joints 12. In the above descrip:tion terms have been used frequently which relate to a circular cross-section of the container. It is obvious, though, that the invention as such is applicable to any arbitrarv cross-section of ti, container as well as of its opening part. Herein arc include" c l forms of cross-sections having curved contours and polygonl cross-sections and combinations thereof. It is obvious that ir accordance with the invention the fixing means is adapted sc tha: on sealing of the container it attaches the wafer l;y providing more than one joint 12.

Ihe above detailed description referred only to a limited number of embodiments of the invention, but it will be readily evidcnt to thcsc versed in the art that the invention embraces a larce number cf embodiments within the scope of the following claims.

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Claims (11)

1. 2. A method as claimed in claim 1, wherein the joint is formed between the edge zone of the wafer and a shoulder facing the centre of the container.
2. 3. A method as claimed in claim 1 or 2, wherein at the temporary 25 fixation against the contact surface the wafer is retained against thn same by vacuum between the wafer and the contact surface.
3. 4. A method as claimed in claim 3, wherein said vacuum is established by connecting channels in said contact surface covered by the wafer to a source of vacuum.
4. 5. A method as claimed in anyone of claims 1-4, wherein an outer sealing means delimits, in a leak-proof manner, a space accomodating the edge region and the storage space of the container the space is evacuated and, whilst maintaining the vacuum, the edge zone of the wafer is fixed, in a leak-proof manner to the attachment means. RA T O 12
5. 6. A method as claimed in claim 5, wherein for the holding of the wafer against the contact surface of the retaining means by a low pressure, the low pressure chosen is lower than the pressure in the evacuated space.
6. 7. A method as claimed in claim 5 or 6, wherein the outer sealing means delimits the space for evacuation through contact against said attachment means.
7. 8. A method as claimed in claims 5-7, wherein said fixing means is displaceably provided inside the oute sealing means and that the fixing means gives cff energy to the edge region after a predetermined time has elapsed after the sealing means has delimited the space accomodating the edge region and the storage space of the container.
8. 9. Apparatus for the sealing of an open container by a sealing wafer, the container having a mouth portion including one or more attachment means adapted to be connected in a leak-proof manner by the wafer by at least one joint, said apparatus comprising: supporting means for supporting the container, retaining means for holding a sealing wafer in a central region of the wafer against a contact surface of the retaining means 20 leaving an annular peripheral region of the wafer free means for pressing the wafer against the contact surface of the retaining means, means for cooling said contact surface at least in a region proximate said perpheral region, means for displacing said retaining means to a position in *o0: which said annular peripheral region is located adjacent to or rests against said attachment means, and fixing means adapted to press said annular perpheral region 0:0. of the wafer against said attachment means and/or to supply energy to o 30 said attachment means to form said joint(s). i 0 It" 1 I 1 1 I '7 13 Apparatus as claimed in claim 9, wherein an outer sealing means is adapted for movement until it rests with a contact part included in the sealing means against the mouth portion of the container in order to delimit space accomodating said peripheral region and the storage space of the container, and that means are provided for the connection of said space to a source of vacuum.
9. 11. An apparatus as claimed in claim 10, wherein the fixing means is enclosed at least partly by the outer sealing means and is arranged movably inside the same.
10. 12. Apparatus as claimed in claims 9-11, wherein means is disposed for producing suction at said contact surface to hold said sealing wafer against said retaining means.
11. 13. Apparatus as claimed in anyone of claims 10-12, comprising a coupling means connected to a driving means, said coupling means, via one or more transfer means, being connected to the sealing means to insure its movement until it rests against the mouth part of the container, said transfer means being adapted so that when the forces .0 exceed a predetermined value they transmit resiliently the forces applied to the sealing means. 20 14. Apparatus as claimed in claim 13, wherein said coupling means is movably supported in the sealing means and/or that the coupling means is substantially connected firmly to the fixing means. DATED THIS 12th DAY OF November 1991 PLM AB By Its Patent Attorneys; GRIFFITH HACK CO. :Fellows Institute of Patent Attorneys ,i "of Australia 0 I" T -1