CA1095396A - Packaging apparatus and techniques for forming closure tops - Google Patents
Packaging apparatus and techniques for forming closure topsInfo
- Publication number
- CA1095396A CA1095396A CA307,995A CA307995A CA1095396A CA 1095396 A CA1095396 A CA 1095396A CA 307995 A CA307995 A CA 307995A CA 1095396 A CA1095396 A CA 1095396A
- Authority
- CA
- Canada
- Prior art keywords
- cup
- film
- web
- plug
- product
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
- B65B31/00—Packaging articles or materials under special atmospheric or gaseous conditions; Adding propellants to aerosol containers
- B65B31/02—Filling, closing, or filling and closing, containers or wrappers in chambers maintained under vacuum or superatmospheric pressure or containing a special atmosphere, e.g. of inert gas
- B65B31/021—Filling, closing, or filling and closing, containers or wrappers in chambers maintained under vacuum or superatmospheric pressure or containing a special atmosphere, e.g. of inert gas the containers or wrappers being interconnected
Abstract
897.034 ABSTRACT OF THE DISCLOSURE
Packaging apparatus for making vacuum or gas-filled packages of the type including a flanged cup-shaped receptacle with a closure film sealed to the flanges and stretched down into the cup to engage and press against the product. The apparatus comprises a first packaging station where the film is sealed to the cup flanges part way around the cup mouth;
simultaneously the film is heated in pre-selected locations to soften it for subsequent stretching. In a subsequent station, the partially-completed package is placed in a vacuum chamber and evacuated. Thereafter, a plug is driven against the still heated film, to force it down into the cup interior adjacent the product. Before or after the plug move-ment, the film is fully sealed to the cup, to make a hermeti-cally-sealed package. While the plug holds the film in its stretched condition, the spaces outside of the film are vented to apply fluid pressure to the film, to cause the film to conform closely to the product shape, and to match closely the contour of the cup.
Packaging apparatus for making vacuum or gas-filled packages of the type including a flanged cup-shaped receptacle with a closure film sealed to the flanges and stretched down into the cup to engage and press against the product. The apparatus comprises a first packaging station where the film is sealed to the cup flanges part way around the cup mouth;
simultaneously the film is heated in pre-selected locations to soften it for subsequent stretching. In a subsequent station, the partially-completed package is placed in a vacuum chamber and evacuated. Thereafter, a plug is driven against the still heated film, to force it down into the cup interior adjacent the product. Before or after the plug move-ment, the film is fully sealed to the cup, to make a hermeti-cally-sealed package. While the plug holds the film in its stretched condition, the spaces outside of the film are vented to apply fluid pressure to the film, to cause the film to conform closely to the product shape, and to match closely the contour of the cup.
Description
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BACKGROU~D OF THE I~VENTION
1. Field of the Invention ., .
This invention relates to packaging techniques and especially to techniques for making vacuum or gas-filled pack-5 ages such as those used to contain food products. In oneLmportant aspec~, this invention relates to improved packagin a~paratus adaptea to form top closures which conform substa~-~iall~ to the shape of the product surface. The disclosed apparatus moreover advar.tageously can make a variety of dif-ferent kinds of packages with only minimal alteration of theequipment to change over from one type of package to another.
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BACKGROU~D OF THE I~VENTION
1. Field of the Invention ., .
This invention relates to packaging techniques and especially to techniques for making vacuum or gas-filled pack-5 ages such as those used to contain food products. In oneLmportant aspec~, this invention relates to improved packagin a~paratus adaptea to form top closures which conform substa~-~iall~ to the shape of the product surface. The disclosed apparatus moreover advar.tageously can make a variety of dif-ferent kinds of packages with only minimal alteration of theequipment to change over from one type of package to another.
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2, Description of the Prior Art Various kinds of packaging machines have been proposea and used over -thè years. Commonly the automatic packaging machines in commercial use make vacuum pac~ages fro~
two continuous webs of plastic film supplied as rollstock, one web being formed into cup-like containers with flanges around the mouth, the other serving to provide top closures which are sealed to the cup flanges. Typically, the lower web is ~irst -thermoformed in-to successive container cups, ana there-after the cups axe advanced together with the upper web throug .
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iL~g5396 one or more packagirlg sta-tions where (1) the top :i5 se~led t.o the cup part-wa~ around its periphery while leaving an evac-uation opening, (2) the package is evacuated through the opening, and (3) the evacuation opening is closed off to completely seal the pac]cage from atmosphere.
For certain t~pes of packages, especially -those made with receptacle cups of semi-xigid ma-teri.al where the upper product surace is below the plane of the cup flanges, it is desirable to stretch-form the top material so that it fits 10 into the cup, somewhat in telescoping fashion, to engage the product surface and thereby permit the product to carry the stress load of atmospheric pressure. There are various ways in wllich such formed tops have been made, as described here-inbelow.
-In one packaging machine, shown in U. S~ Patent
two continuous webs of plastic film supplied as rollstock, one web being formed into cup-like containers with flanges around the mouth, the other serving to provide top closures which are sealed to the cup flanges. Typically, the lower web is ~irst -thermoformed in-to successive container cups, ana there-after the cups axe advanced together with the upper web throug .
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iL~g5396 one or more packagirlg sta-tions where (1) the top :i5 se~led t.o the cup part-wa~ around its periphery while leaving an evac-uation opening, (2) the package is evacuated through the opening, and (3) the evacuation opening is closed off to completely seal the pac]cage from atmosphere.
For certain t~pes of packages, especially -those made with receptacle cups of semi-xigid ma-teri.al where the upper product surace is below the plane of the cup flanges, it is desirable to stretch-form the top material so that it fits 10 into the cup, somewhat in telescoping fashion, to engage the product surface and thereby permit the product to carry the stress load of atmospheric pressure. There are various ways in wllich such formed tops have been made, as described here-inbelow.
-In one packaging machine, shown in U. S~ Patent
3,545,163 issued to R. A. Mahaffy, et al, semi-rigid cups formed in the lower web of plastic film move through three successive packaging stati.ons together with the upper web.
In the firs-t station,.an "ini-tial" or partial seal is made between the upper web and -the peripheral ~lanye around the mouth of each corresponding cup;:at the same time, heat is transferred to a part of the upper web inboard o the seal ne, to soEten the plastic for subsequ~nt stretch-forming. :[¦
the seond station, the heat-softened portions of the upper web are stretched upwardly, away from the cup, to make a top having the appearance somewhat of an upside-down cup, and having a depth approximately equal to the distance between the flange plane of the product-containing cup and the upper sur-faces of the product in the cup; the second station also included means to chill the stretch-formed upper web while held in its stretched condition, thereby to prevent shrin~-bac~ of the plastic. The formed webs then are shifted ~o thethird station where the formed top~ s inverted and forced down into the product cup to be pressed against the top surface of the product; also at ~his station, the package is evacuated, and a final seal made at the vacuation openiny.
~ ' ' ~ ' It will be clear that the shape of the formed top in ¦
the apparatus described above is effectively controlled by the top-forming recess in -the second station When used with pro-ducts having a relatively fla-t surface, such as sliced luncheo meats, a top formed in such apparatus can provide reasonably close conformi-ty to t~e product shape, especially when the top ma-terial is thin and fleæible. ~oweverl where the top web is ¦
relatively -thick and/or stiff, e.g. semi-rigid plastic, or whe e the top contour of -the product is substantially irregular, it is not readily possible to obtain the desired excellent con-formity between the -top and the product surface. The machine _4_ . 1.
. '., 39539~i 1 described above also is not well adapted for ready inter~
changeability between di-fferent product types, since it uses a series of trays to carry the semi-rigid cups through the packaging sequences, and such trays cannot easily be altered to suit various product types.
U. S. Patent 3,805,486 shows a later machine which also uses the -technique of formin~ the top in a station pre-ceding the evacuation-and-final-seal station. In this machine , the top is formed from the lower web of (flexible) plastic, and the product is placed on the formed top prior to its assem _ bly to the cup formed in this case from the upper web. The lower web is conveyed through the operating stations by edge clamps rather than by trays as in the previously-described machine. ! -. ' . ~
In another machine, shown in U. S. Pat~nt 3~695,900, the top is formed in the ~inal-seal station. The preceaing station serves the usual initial-seal function, and also pro-vides for trans~er of heat to the upper web to prepare it ~or subsequent stretch-forming. The final-seal sta-tion includes the usual vacuum chamber which serves to evacua-te the package prior to making the fi~al seal. When the vacuum chamber is vented, atmospheric pressure will force the heated top web down against the product. In this manner, -the upper web of the package can be made to conEorm somewhat to the product profile.
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~ -5-~S3g6 i However, -the arranyement described in that patent i5 not fully sa-tis~actory for a varie-ty of product t~pes. In part:icular, the hea-ted plastic of the top may shrink back to set up stresses in the packa~e tending in certain applica-tion~ ;
to physically distort the package, e,g~ especially with semi-rigid container cups o~ only moderate'thickness or stiffness, Moreover, since the Eorce which presses the top down again~t the product is proportional to the differance between atmo-spheric pressure and the pressure in the package, it will be evident tha-t the top-forming technique disclosed in thîs pate I-t is not well suited for use in making gas~filled packages, Still another limitation with this technique is that it some-times has a tendency to produce thinning-out or puncturing of the plastic in the regions where stretch-forming is e~fected.
:~ ~ : ' , ' U, S. Patent 3,972,155 shows another top-forming arrangemen-t wherein the top formation takes place in the final seal-and-evacuation station, Figures 4 and 6 o~ that patent show the use of a plug flxed to the roof of the vacuum chamber, to press down against the film while the chamber is I ZO being closed prior -to evacuatlon of the pac~age, Subsequent venting o~ the chamber applies pressure to the top web to for that web down towards the product.
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It also is known in the art to pre-form the top closure in a separate operation, to apply such formed top to the container cup in an evacuation chamber, and then vent the chamber, ~lthough this approach has been effective for - 109~396 certain applications, it re~uires very close product contro:L
and -tooling Eor eacll ind;vidual package shape, since ~11 of the elements (i.e. the recep-tacle cup, the product, and the formed top) must fit exactly, in a custom-tailored arrangement for each par-t:icular produc-t. Thus this method is costly ~o carry out, because of its close tolerance requirements, and also lacks versa-tility since each product shape must have its own unique tooling.
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SUMMARY OF THE INVE~TIQN .
It is a principal object of this invention to pro-vide improved techniques and apparatus fox forming the top closure of a vacuum or gas-fllled package, so as to avoid or minimize the disadvantages of the prior art such as discussed above. A related object of the lnvention is to provide econo~ _ ical apparatus which can flexibly be used to package a variet~
of diffexent products, without requiring extensive changeover modiications.
. . l In a preferred embodiment of the invention, to be described hereinbelow in detail, -two continuous plastic webs ~the lower one formed into cups) are carried b~ an intermit-tently-indexed edge-clamp conveyor through two successive packaging stations. In the first or initial seal station, the upper web is sealed to -the associated cup around subs-tan-tially the entire peripheral flange thereo, leaving an unsea ed ' . . l -7~ :~
. ' .,' 1~5396 xegion adjacent an evacuation slit previously cut in the lower web; sïmultaneously, the upper web is selec-tively heated in regions which are subse~uently to be s-tretch-formed. In the second or ~inal seal statlon, the package is placed in a vacuum chamber and evacuated through the evacuation slit A~ter the start of evacuation, a plug, shaped to ma-tch the package top, is driven down z.gainst the upper web to force the previously heated and still soft and formable top closure : downward into the receptacle, stretching the film towards the product, preferably to the sur~ace of the product. Thereafter the evacuation slit is sealed off to complete the final seal of the package, and the upper par:t of the vacuum chamber is vented, advantageously to a pressure higher than atmospheric.
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It has been found tha~, in the machine to be descri~ ed, 15 : the composite of forces acting on the top closure will form the top film closely into conformity wlth the surface of the product, even though the product shape be substantially irregular. Moreover, the top film will be forced tightly intc : any depressions or poc~ets in the package interior. The result is a package with minimal distorting stresses or voids, and a ~ompletel~ encased and immobilized product with sharp definition of contours, providing a superior appearance.
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Other objects, aspects and advantages of t.he inven-tion will in part be pointed out in, and in part apparent ~rom ~5 the following description of preferred emhodiments~ considered together with the accompany.ing drawings.
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~L~g53~6 DESCRI.PTION OF rr'HE DR~WINGS
FIGURE 1 is a top plan view o:E packaging apparatus in accordance with this invention wherein product being packaged moves from right-to-left;
FIGURE 2 is a front elevation o~ the packaging apparatus of Figure 1~
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FIGU~E 3 is a bottom plan view of the two-station packaging head of the machine, i.e. looking upwardly at it from underneath;
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FIGURE 4 is a perspective view illustrating -the progressive steps of the packaging material as it proceeds through the apparatus in accordance with this invention;
FIGURE 5 is a perspec-tive view of a completed. ~:
pac~age of round luncheon meat as it would be seen by the consumer, i.e. inverted from the way it would actually have passed th.rough -the packaging apparatus; .¦
FIGURE 6 is a vertical cross-section ta~en along line 6-6 of Figure 2 through the first station of the packagin apparatus and showing the first step of two packages being -formed simultaneously, side-by-side; . -. ~ -11119539~i FIGURE 7 is a vertical cross-section taken along line 7--7 of Figure 2 and showing the second sta-tion of the packaging apparatus; ~or convenience in Lllustration, the two s.ides of Figure 7 show different stages o~ the process carried out in the second station, with the stage on the right pre-ceding that on the left;
. ', FIGURE 8 is a vertical longitudinal section taken al line 8-8 of Figure l through both the first and second station , showing progression of the product through the packaging apparatus; 1 .. , . ,1.
FIGURE 9 is a section corresponding to Figure 7 but .
showlng the packaging apparatus being used for the packaying of frankfurters~ and with both plugs in the down position;
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FIGURE 10 is a detail vertical cross-section of a pa t I
of the second station showing a modification whereby the packa e ¦
!may be given an elevated base to better display its contents, . ' . 11 .
FIGURE 11 is a perspective view of the package which has been formed in the modification of Figure lO, inverted from the way the pacXage is shown in Figure lO. ,.
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FIGURES 1 through 8 illustra-te packaging apparatus in accordance with this invention used for the pacXaging of round sliced luncheon meat. FIGURE 9 shows a modified arrange-en-t used for packaging frankfurters.
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-- ~ gl~39S39~i DEq'AILED DES~RIP~ION OF PREE'ERRED EMBODI~ENTS
. ~ , ' ' . 1, Referring now to the right-hand por-tion of Fiyures and 2, a series o~ product-filled receptacle cups 20, pre-iously formed as side-by side pairs in a web 2~ of semi-rigid ~lastic film, are advanced from right-to-left in and through two-station pa~Xage-forming unit 24r This unit includes a ~ase 26 below the web line, and a packa~in~ head 28 above the ~eb line The base and head are supported by conventional ~¦
vertically-movable frames or beds (not fully shown~ ~driven in ynchronism to reciprocate the base and head in opposite ~ ;
~irections, i.e. to provide an opening and closing move~ent ~f those two parts. ~
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The web 22 is carried by~an edge-c-amp conveyor 30 ~riven with an intermittent indexing motion ln synchronism ~ith ~he reclprocating movement of the base 26 and head 28.
n a cycle of operation, starting from the closed position .hown in Figure 2, the base and head first are reciprocated part, the cups 20 then are lndexed forward one step into ~ ~ ~heir new position~between the base and head, and the base ~nd head then are moved back together into closed position as hown, surrounding t~e enclosed cups. Mechanisms for develop-ng the intermittent indexiny movement of the conveyor 30 are -ell ~now nd thus will rot be detailed here~n.
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~ o the right o~ t'he package-formlng unit 24 an upper web 32 of ~ormable plastic film extends down cmd around a lay-do~n roll 34 which serves to apply the upper web over the receptacle cups 20 (see also Figure 4) befoxe the cups enter the package-forming unit As the upper web moves through the package-forming unit 24, it is sealed to the cups, and formed into closure tops which conform closely to the cup and product configurations~ The upper web is drawn from the usual supply roll, and is suEficiently wide to cover both cups of each side by~side palr, including the side flanges thereof. The uppex web 32 in the disclosed embodiment is of semi-rigid (5-15mil.) heat~formable plastic ~ilm with a coating of heat-sensitive peelable sealant compatible with the heat-sealing properties o the cup material. The packaging materials will h~ve predeter-~ined characteristics, such~as oxygen barrier, water vaportransmission rake, oxygen scavenging additives, etc., in ccordance wlth the partlcular product packaging requirements r : . ~ ' Referring now also to Figure 6, it will be seen that l n the first or "initial seal'~' station o~ the package-forming ~ni-t 24, the cups 20 are positioned in corresponding sealing d e ~avities forming par-t of the base 26~ These die cavities inol de ulti-part d~ fillers 38 shaped to match the cup configuration to provide firm support therefor. Surrounding each die avity is a temperature-resistant sealing bead 40 which, . .' `` ~`
~095396 when the packaging head 2~ has moved down to closecl posi.t:ion (as shown), is aligned ~.ith peripheral heat-sealing bars 42 o:E the head ~. These bars ex-tend around the three outer flanges of each cup and partially along t.he four~h flanges in the cen-tral region between the two cups. When the head descends into closed position, it presses the top closure film 32 and the cup flanges between the hot seal bars and the ..
sealing bead to effect a seal against air leakage part way around the cup mouth. The sealing bars are supplied with hea-t by electrical heating rods 44. .
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Af-ter the packaging head Z8 has moved down to engage the base 26, vacuum is developed ~as will be described) above the upper film 32 to draw that film upwardly and press it against a pair of side-by-side platens 46 (one for each cup 20) which are heated in selected regions by corresponding heating blocks 48. These blocks contai.n heater elemen-ts 49 and are separate from the heaters for the initial-seal bars -42. For round cups 20 to be used for flat produc.t tas shown), this platen is arranged to apply heat only to the regions o~
the upper web which are .just inboard of the corresponding i cup walls Thus, referring now to Figure 3, each platen ~ .
is.circular in outline, and comprises an outer heated band 50 (preferably formed with a slight concavity as shown in Figure ..
6~, and a non-heated circular heat-impeding insulator 52 .
~ 1095396 ~on-heated corner insulating members 54 also are positioned in the spaces a.round each platen 46 to minimize transfer o.~ heat to that part of the film, and to prevent d.istortion o~ the ~ilm which could result rom excessive film movement during the application of vacuum. A central insulat-ing member 56 is positioned between the -two platens to prevent : so~tening of the web in that region, so as to assure proper functioning of a web~ ter .in the next operating station as will be described. An insulator 58 (Figure 6) also is posi-: tioned between each heating block 48 and the outer parts of the head 28 to permit separate regulation of the temperatures of the heating blocks and the initial heat-sealing bars 4~.
On opposite sides o~ the central insulating member 5~
are~Einal-seal-area preheater regions 60 the operatlng surac s of which are contoured up a small dlsiance (e.g~ l/16") above ~ the plane of -the initial:heat-sealing bars 42. The insulator .
: I 56 is similarly contoured, as indicated by the break-line 59 :
: on Figur~e 3. The sealing bead 40 i5 interrupted in the area adjacent the preheaters 60 to prevent any inadvertent sealing wh~`~ch mlght obstruct air flow through this region during the subsequent evacuation o the package in the next stat.ion. .
Such preheating o~ the final seal area is particularly valuab e when making packages with semi-r1gid closures; reference may : be made to ~. S Patent 3,438,1~5, where this problem is dis-cussed, and means are described ~or positively pushing a top closure member against a preheater element by introducing air pressure into the package~
' -1~~' . '',''' ~s396 . i In the embodiment d~scribed herein, the top ~ilm 32 is moved up agains-t both the preheaters 60 and the platens 46 1 , b~ developing a vacuum above the top film 32. The achievement of desirably uniform vacuum is aided by the use of small vacuu~
orifices 70 drilled through the heating platens 4GD The vacuum also is applied through the gaps between -t~e platens and adJa-cent parts such as insulators and -the like.
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This vacuum is applied to the packaging head 28 through a valve-controlled vacuum port 72. The controL valve (not shown) for this port is synchronized with the machine operating cycle in such a fashion that vacuum is applie~ when the initial heat-sealing bars 42 contact -the upper webi 32.
The vacuum remains on during -the "dwell" portion of the indexing cycle, providing for transfer of the proper amount o~ heat to the upper web 32. The initial seal statlon then .is vented to atmosphere ~hrough its vacuum port 72, and the base 26 and head 28 are parted. When -~he base and head have moved su-fficiently -far apart, the lnde~ing cycle resumes, and t~e packages with their top closures now partially sealed to the cup 20, hea-ted sufficiently for forming b~ the heating platens 46, and preheated in the final seal areas, are trans-ferred to the next successive operating station where forming of the top closures will take place, along with evacuation an final sealing of -the packages.
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109539~
Referrin~ now -to FicJIl.re 7 5howiny -this E.inal-sea'l--and-evacuat:ion station wi-th t:he base 26 and -t~e pac~aginq heac' 28 closed, the cups 20 again are supported by appxopri.atel~
shaped multi~part die fillers 74. The base and head serve as clamps to press the packaging material together and to make air-tight sealing engagement with -the two webs oE packaging material so as to establish upper and lower vacuum chambers surrounding the partially-sealed packages~
The side walls 76 o the packaging head 2~ in the final-seal stat.ion are cooled by water passages 78 ad]acent the hori~ontal surfaces which press down against the previous-ly heat-sealed regions of the upper fLlm 32. This provides ¦
rapid chilling and setting of the heat~activated sealant serv ing to rninimize shifting or separation of the seal as a resul o~ stresses imposed on the seal areas during the s~sequen-t evacuation, forming, final sealing and venting operations yet to come in this station. This chilliny of the initial-seal areas is accompanied by squeezing of the package flange seals between the flat horizontal surfaces of the packaging head :20 side walls, and the flat elastomeric sealing surfaces B0 on the upper edge of the mating side walls 82 of the base 26~ :~
: The seal contours of this elastomeric sealing surface e~{tend 'a small distanFe outwardly beyond the initial seal area, i.e.
laterally outwards of that seal area. This overall arrangeme It develops an ironing action to provide the pacXage with a fla-t . undistorted ~lange superior in appearance and function to pacXages made by conventional means.
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With the base 26 and pac~agi.ng head 2~ in closed position (as shown in Figure ~), a web-lifter 8~ is in known manner driven upwards throu~h a previousl~~formed evacuati.on slit in the lower web 12 to engage the l.ower surEace of the upper web 32 and raise that web up a small distance above the lower web. Such displacement of the upper web establishes large-capacity evacuatlon channels leading from the interior of each cup 20, through the as-yet unsealed region along the interior flanges of each cup, and down through the evacuation .
slit, the web-liEter bore 86, and the spaces beneath the d.ie fillers 74 to respec.ive conduits 88 coupled to the base 26 A control valve (not shown) Eor conduits 88 is actuated to apply vacuum to this evacuation channel, and the package evac uation begins.
. Simultaneously with the appllcation oE vacuum to conduits 88, a separate valve (not shown) is actuated to appl vacuum through a pair of conduits 90 to the upper vacuum cham ber, comprisLng the spaces above the upper web 32~ In certail ¦
aEplications, the web-lifter a4 may not be required for estab _ I
lishing -the evacuation channel leading to the cups 20, since I :
: when the spaces a~ove ths web 32 are evacuated, the initial internal air pressure within the package tends to force the upper we~ up, away from the lower web 22, for at least a por- . J
tion oE the evacuation cycle.
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~L095396 ~ ~
. :tn any event~ when the spaces ou-tside o:E the packag ~s ¦
a:re e'vacuated, the air pressure ini tially in t.he package, i.e~ at the start of package evacuation,, produces forces on t'he packaging material pushing it outwardly in al L directions This develops s tresses which tend to cause dis tor tion in the package configuration. It has been :found to be important, for minimizing such distor tion of the cups 2 0, -to support the cups in die-fillers 74 of matched shape. The upper sur-faces of these fillers are in the same plane as the elasko-meric sealing surface 80 on the base side walls, in order to prevent distortion of the packaye flanges. This elastomeric sealing surface also is' extended at 92 into the evacuation s lit region to provide additional support :Eor the flanges in that region This extended surface tapers slightly downward as it approaches the evacuation slit to assure that the air can 10w from within the package without undue restriction .
: during evacuation. --It also has been found to be important to prevent the upper web 32 from moving a significant distance upwards 2 0 : above the web line during this period of posi tive pressure I . -differential within the package, in order to prevent stretchi lg I
~f the previously-heated film. In the region over the evac- t uation slit and the web-lifter 84, a fla-t restraining e'lement i, 94 is fixed in position to restrict the upward web movement of the closure film. The distance between -the :Eilm ana this :-..
~1095.~96 restraininy element is about l/lG'` to allow t~e web to r.ise only enough for rapid evacuation and optional gassing oE the ~ackage interio.r. This restraining element desirably is forme of heat~insulating material to prevent the upper web 32 from labsorbing excess heat rom a final seal bar 112, to be describ~ld ~ereinbelow, which is di.rectly over the interior flanges adja-~en~ fLnal seal areas.
Upward movement of the web 32 also is restricted by th~
lat surfaces of a pair of vertically movable, top-orming plu s 00 to be described below, and by the flat surfaces of insulat ng filler inserts 102 surrounding those plugs~ (~ote: The et-hand plug is shown in its down position, for convenlence f illus-tration, but i-t will be understood that both plugs mov : p and aown together, and that both plugs are in their upper osition as package evacuation beglns.~ When the plugs are in ~heir upper posLtion,-their lower suraces, and the su:rfaces o he insulating insert 102, may be within 1/32" o the surace the upper web 32. ...
.' Preerably the elements touched by the uppeF web 2, as it is forced upwards, are made of hea-t-insulating mate-ial, at least in the regions thereo which are opposite film reas heated in the preceding station, in order to avoid xcessive loss of heat from the film so as to maintain the Eilm at formable temperature. For especially long evacuation ycles, or or use with films which require additional heat o maintain a formable temp~rature, it may be des:irable to add pl~g heater, such as one u~ilizing conventional tubular elem~nts illustrate~cl at 10~ (shown onl~ or the le~t hand plug ¦
The plug heaters would transfer heat by conduct:ion to th~
movable plugs made in this case o:E a heat-conducti.ve materia:L
such as aluminum, and having a high-temperat:ure plastic releas ?
5 ~ coating (e.g. Teflon) on their lower sur~aces. Desirably, the plug mechanisms are insula-ted from the outer chilled surfaces of the head 28 by means of flat insulators 106.
i Turning now to the operation of the top-forming plug 100, when the evacuation of the packages is well underway and approaching completion, the plugs are driven downwardly by the vertically-reciprocable shafts 108 of respective air-operated c~linders 110. These cylinders are controlled ~y air-valves ¦(not shown synchronized with the machine operatiny cycl~ Th~
descending motion of the plugs stretches the previously heated and still soft and formable, top closure fllm 32 down into each cup 20 and towards the product therein. The downward movement o~ the plugs 100 also aids in rapid evacuation of the packages~
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Satis-factory functioning can be achieved by driving the film 32 down to within a srnall dis-tance from the top of the product. However~ maximum corner definition and elimina- ¦
tion of substantial distorting residual stresses in the pacXag~
are obtained by stretching -the film all of the way down to the , surface of the product. The stroke depth is adjustable by means of nuts 109 limiting -the downward motion, and an anti-rotation arrn 111 also is provided.for use with non-round plugs v~ a f~ e ~2r~
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- ~953~
Preferably, the plugs are formed with sharply rad.iused side edges shaped -to closely conform to the cup sidewall perim-eter, e.g within 1/32", so that the side walls of the ~ormed tops desirably are in very close proximity to the side walls o.
the cups. The pluy shape may however va:ry acc~rding to the di~ len-sions and special requirements of the package and the product.
The plugs thus advantageously are arranged for easy interchang _ ability as by -the use of a simple fastener to hold them in pla, e.
: .
After the plugs have reached -the ends o~ their stroke, and evacuation is complete, a ~inal seal is made in the previ-ously unsealed regions along the adjacent interior cup flanges This is accomplished by a heated final-seal bar 112 which is I .
driven down by an air-operated act~ator. 114 to press against ¦ :
the upper web 32 with an appropriate degree of pressure. This .. I
seals the two webs toge-ther to complete the seal along the . ~.
entire periphery of the ~flanges surrounding each cup mouth.
Thereafter, the control valve for the upper conduits 90 is activated.to apply air under pressure to the pac~aging I .
: . head 28. Thus the spaces above the evacuated pac.kages are pressurized to a level above atmospheric pressure. The down- ~.
ward force of this air pressure, acting in combination with the stretching force of the plugs 100, stil3. held in their lower position, completes the proper forming of each top closu by pressing the still-heated ~ilm 32 intimately and tightly down again~t the surface o~ the product, so as to follow closely its contour or profile including any pockets or voids.
5:~g~
¦iTherea~ter, the upper and lower chambers are ventea to atmo-sphere, the base 26 and packaging head 28 are separated, and ¦the pac~ages are indexed out of the packaging head The com-!pleted packa~es are desirably free from distorting stresses o S ~voids, and the contained products are held immobilized with clear definition of their contours.
I . ~' The description above relates to the formation of a straight vacuum package. In some cases, it is desired to ~orm a gas package, i.e. a package having a small amount of gas her me~ically sealed therein, especially iner-t gas. The machine described herein can readily make gas packages, with minor changes to the package-forming procedures as set out below.
As in the process for making straight vacuum package , the upper web 32 first is selectively heated in the ini~ial seal stage as described, and then is transferred to the final seal stage ~or in-place ~orming of the tops and co~pletion of the packages. In the final seal stage, the initially-sealed pacXages are evacuated through the evacuation slit with the aid of the web-lifter 84, and the valve controlling the lower conduits 88 then is shut o~f. Thereafter a selected gas is supplied through an internal passageway in the web-lifter I -84 (in accordance with known techniques) into the package interiors. ~f-ter a predetermined amount of gas has been admitted, the final seal bar 112 descends from above the web 32 to complete the heat sealing of the packages. As ~ . 1, lOg539~
beEore, this final seal ~oins the preliminary seal lines to make a comple-te hermetical seal around the entire periphery of the flanges around the cup mouth. .
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With the package compl.etely sealed, the plugs 100 descend and press the upper web 32 down towards and against the packaged product, compressing the gas previously admitted to the package and thus increasing its concentration, As the plugs reach the limit of their travel, the upper vacuum cham-. ber is vented, as b~ means of a three-way valve~(not sh~wn) in the conduit lines 90, to connect a regulated source of air pressure to the upper chamber. This inrush of pressurized . air above the web 32, which has already been mechanically s-tretched and somewhat formed by the plugs 100, serves -to .
force the warmed, formable film down into the cups 20', agains :15 the side walls of the cups, in-to any side wall cavities forme in the~cups, and down over the product in the cups, around -th contours thereof, until the pressure of the gas in the packag is equal to the pressure of the air supplied to the upper chamber. At this stage, the top web 32, being held down b~
the plugs 100, and forced against the product and cup, is chilled as it contacts the product and cup, and holds its for and contours, matching those of t~e product and other element against which it has been pressed.
The lower the pressure of the ga5 introduced into the package .relative to the air pressure used to vent the upper chamber, the more closely -the top closure film will . . ,.
~~_ l fol ow tho contours o~E the proauct: and the cup. The action of the plugs 100, however, in stretching and forcing the -top closure film down in-to the cup i5 independent of -these vari-ables and thus provides a top film forma-tion superior to tha-t obtainable by conventional means. The physical stretching of the in-terior marginal portions of the top film inwardly aroun the product and outwardly to the cup 20, especially to a permanent set dimension, is desirable be~ause it tends to eliminate any substantial build-up of tension in the film.
., i .... -The film is formed to folIow the contours of the c lp, and the force of atmospheric pressure is carried essentially by the pac~aged product, aided by the internal gas pressure.
This avoids placing portions of the package under heavy stresses, and minimizes dis-tortion of the cup, whether flexible or semi-rigid (as in the preferred embodiment~, from its original shape. The plugs 100 remain in their down position during venting of the top chamber, and if the plug face is ligh-tly pressing ayainst the product, this pressing o~f the -top film on-to the product will have the added bene-ficial effect of immobilizing the product without distortion 1, while the product and cup are subjected to the venting pressu e forces previously referred to.
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10~53g6 A~ter the top film 32 has chi.lled, the lower chamber is vented to atmosphere, the pluqs 100 are retrac-ted, the base 26 and the packaging head 28 separate, and the air pressure to the upper chamber is cut o~f. The conveyor 30 indexes forward one more step, and the procedures developed .
are xepeated.
It has been found thatmax~mum shaping of closure to product and cup is obtained w1th a vacuum package as the differential pressures between the package interiox and above t~le closure are maximized. Under these conditions, the heate formable closure film 32, driven by the plugs 100 and acted OI .
by the difEerential pressure resulting from vacuum. in the package and posi-tive ai.r pressure in the upper chamber,vill .
orm closely and intimately into and around the contours o tl .e product, and the cup, to produce a package of supexior appearance.
.' . ., One o~ the important virtues o~ -the pac~aging appa-ratus described is its flexible adapta~ility to a vaxiety of -packaging requirements. Probably of most siynificance in thi .regard is that the apparatus will produce packages the tops of which are automatically confo.rmed to differing contours ~or pro iles without r-quiring any changes in the apparatus ~ ~ S3~ 1 to accomodate such product variations This adaptability is a consequence o~ the fact that the closure top i.s ~ormed, while s-till warm, in such a manner that it is shaped by the prod~ct, ra-ther than being shaped by a specific~ prese-t die, or the like, designed to approximate an average product con- ..
tour. This advantage of the invention is not best demonstrate d by the illust~ated package of sliced bologna, since the top surfaces of bologna are relatively smooth, but would be bet-ter exemplified by the packaging of irregular products~
In addition, the descr-ibed apparatus can readily be .::
altered, by relatively simple change-over of parts, to shift from the packaging of one type of product to a quite different product. This is illustrated for example by Figure 9 which ic comparable to Figuxe 7 but shows the final seal stage arrangec for packaging frankfurters rather than bologna.
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In the modified machine of Figure 9, the plugs lOOA
ha~re a rectangular plan configuration matching ~he shape of a l rectangular cup 20A carrying the fran~furters. In the corre-sponding initial seal stage ~not shown), the upper web 32 is selectivel~ heated throughout a rectangular area opposite the rectangular mouth o~ the CUp, to soften that entire region of the upper web for forming in the final seal stage.
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. ,' ---`` ~L~953916 rrhe pr-ocedures fo:llowed :ln the :Einal stage ~re l:ike -t:hose previously described. The p~ckage evacuation f:irst .is initiated, and shortly thereafter the plugs lOOA are driven down to stretch the heated rectangular film area su~stantiall~
to the upper surfaces of the ~rank:Eurters. Final sealing of -the package then takes place, ater which the upper vacuum chamber is vented to positive pressure, i.e. above a~mospheric , while the plugs remain down and vacuum is maintained in the lower chamber. The positive pressure forces the still-heated film down around the side of the frankfurters (as illustxated in the left-hand unit), to follow the contours thereof closel~ -The resul~ing package thereby présents a sharpl~ defined, rigialy immobilized product, without dis-tortion, and clearly visible to a prospective customer. j : . .
Figures 10 and 11 illustrate the formation of still ano-ther type of package, wherein round bologna is held in a :~
specially-shaped receptacle 2QB providing a square platform or pedestal 120 between the package flanges 122 and the round , product-containing portion 124. To develop this two-level configurationy the top-forming plugs lOQB are shaped in a stepped arrangement, comprising a lower round portion I26 to match and fit within the round section o t~e receptacle, a~d an upper square portion 128 to match and fit within the corresponding square pedestal section of the receptacle As in the pre~ious embodiments, these plugs are driven down against the selectively-heated upper web 32 and serve, ~ ~ 10~15336 especi~lly in coIIjunction wl-th the pressure d:iE:Eerenti.al from ~the subse~uent venting of the upper char~er, to -Eorm the closure top in such a way that, as shown in Figure 11, .i.t provides a round section 130 and a square section 132 pre-1 cisely matching the receptacle shape and product configuratiorAlso, as in the Figure 6 arrangement, the pre-heating pla-tens in the initial seal stage will be so constructed as to selec~
Lively heat particularly those regions a:E the upper we~ which are to be stretch-formed in the final seal stage, so as to 10. produce the package as shown~
. ,~' It will be understood from the a~ove descrip-tion o preferred embodiments of the invention that apparatus followi the teachings of thls .invention is especially adapted to afford Elexible and versatile operation in producing excellen packages for products of various shapes and configurations. ¦
The invention finds special applicability for use with produc s o~ irregular shape, since with the unique top-~orming proce-dures described, the product itself controls the contour of th~ top closure. Thus, even though the product profi1e chang from unit to unit as they enter the machine, each closure top will automatically be conformea to its corresponding product. .
The apparatus also has the capability of making packages from a variety of different packaging ma-terials, in-cluding flexi~l.e and semi-rigid packaging ma-terial, plastic o -2~-o-therwise, whe-ther used for -the receptacle cup (lower web~ or the closure top (upper web). The versatility of the apparatu is still further enhanced b~ the ready interchangeability of the basic operating cornponen-ts so as to suit different types o:E products and/or package configurations. Such changeover in the preferred embodiments disclosed does not re~uire sub-stitution of a complete series of receptacle-supporting tra~s since bo-th webs of pac~aging material are supported by an ,.
edge-clamp conveyor adaptable to all kinds of packages Also although an intermlttently-indexed conveyor is shown, it will be appreciated that continuous-motion operation can be used, in accordance with well-known techniques.
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Accordingly, although specific preferred embodiment of the invention have been described in detail hereinabove, it is desired to e~phasize that ~his is for the purpose of illustrating the principles of the invention, and should not nec~ssarily be constru.ed as being limiting of the invention since it is.apparent that those skilled in this art can make ~ many modified arrangements of the disclosed apparatus wikhout departing from the true scope of the inven-tion~
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~E CL~
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In the firs-t station,.an "ini-tial" or partial seal is made between the upper web and -the peripheral ~lanye around the mouth of each corresponding cup;:at the same time, heat is transferred to a part of the upper web inboard o the seal ne, to soEten the plastic for subsequ~nt stretch-forming. :[¦
the seond station, the heat-softened portions of the upper web are stretched upwardly, away from the cup, to make a top having the appearance somewhat of an upside-down cup, and having a depth approximately equal to the distance between the flange plane of the product-containing cup and the upper sur-faces of the product in the cup; the second station also included means to chill the stretch-formed upper web while held in its stretched condition, thereby to prevent shrin~-bac~ of the plastic. The formed webs then are shifted ~o thethird station where the formed top~ s inverted and forced down into the product cup to be pressed against the top surface of the product; also at ~his station, the package is evacuated, and a final seal made at the vacuation openiny.
~ ' ' ~ ' It will be clear that the shape of the formed top in ¦
the apparatus described above is effectively controlled by the top-forming recess in -the second station When used with pro-ducts having a relatively fla-t surface, such as sliced luncheo meats, a top formed in such apparatus can provide reasonably close conformi-ty to t~e product shape, especially when the top ma-terial is thin and fleæible. ~oweverl where the top web is ¦
relatively -thick and/or stiff, e.g. semi-rigid plastic, or whe e the top contour of -the product is substantially irregular, it is not readily possible to obtain the desired excellent con-formity between the -top and the product surface. The machine _4_ . 1.
. '., 39539~i 1 described above also is not well adapted for ready inter~
changeability between di-fferent product types, since it uses a series of trays to carry the semi-rigid cups through the packaging sequences, and such trays cannot easily be altered to suit various product types.
U. S. Patent 3,805,486 shows a later machine which also uses the -technique of formin~ the top in a station pre-ceding the evacuation-and-final-seal station. In this machine , the top is formed from the lower web of (flexible) plastic, and the product is placed on the formed top prior to its assem _ bly to the cup formed in this case from the upper web. The lower web is conveyed through the operating stations by edge clamps rather than by trays as in the previously-described machine. ! -. ' . ~
In another machine, shown in U. S. Pat~nt 3~695,900, the top is formed in the ~inal-seal station. The preceaing station serves the usual initial-seal function, and also pro-vides for trans~er of heat to the upper web to prepare it ~or subsequent stretch-forming. The final-seal sta-tion includes the usual vacuum chamber which serves to evacua-te the package prior to making the fi~al seal. When the vacuum chamber is vented, atmospheric pressure will force the heated top web down against the product. In this manner, -the upper web of the package can be made to conEorm somewhat to the product profile.
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~ -5-~S3g6 i However, -the arranyement described in that patent i5 not fully sa-tis~actory for a varie-ty of product t~pes. In part:icular, the hea-ted plastic of the top may shrink back to set up stresses in the packa~e tending in certain applica-tion~ ;
to physically distort the package, e,g~ especially with semi-rigid container cups o~ only moderate'thickness or stiffness, Moreover, since the Eorce which presses the top down again~t the product is proportional to the differance between atmo-spheric pressure and the pressure in the package, it will be evident tha-t the top-forming technique disclosed in thîs pate I-t is not well suited for use in making gas~filled packages, Still another limitation with this technique is that it some-times has a tendency to produce thinning-out or puncturing of the plastic in the regions where stretch-forming is e~fected.
:~ ~ : ' , ' U, S. Patent 3,972,155 shows another top-forming arrangemen-t wherein the top formation takes place in the final seal-and-evacuation station, Figures 4 and 6 o~ that patent show the use of a plug flxed to the roof of the vacuum chamber, to press down against the film while the chamber is I ZO being closed prior -to evacuatlon of the pac~age, Subsequent venting o~ the chamber applies pressure to the top web to for that web down towards the product.
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It also is known in the art to pre-form the top closure in a separate operation, to apply such formed top to the container cup in an evacuation chamber, and then vent the chamber, ~lthough this approach has been effective for - 109~396 certain applications, it re~uires very close product contro:L
and -tooling Eor eacll ind;vidual package shape, since ~11 of the elements (i.e. the recep-tacle cup, the product, and the formed top) must fit exactly, in a custom-tailored arrangement for each par-t:icular produc-t. Thus this method is costly ~o carry out, because of its close tolerance requirements, and also lacks versa-tility since each product shape must have its own unique tooling.
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SUMMARY OF THE INVE~TIQN .
It is a principal object of this invention to pro-vide improved techniques and apparatus fox forming the top closure of a vacuum or gas-fllled package, so as to avoid or minimize the disadvantages of the prior art such as discussed above. A related object of the lnvention is to provide econo~ _ ical apparatus which can flexibly be used to package a variet~
of diffexent products, without requiring extensive changeover modiications.
. . l In a preferred embodiment of the invention, to be described hereinbelow in detail, -two continuous plastic webs ~the lower one formed into cups) are carried b~ an intermit-tently-indexed edge-clamp conveyor through two successive packaging stations. In the first or initial seal station, the upper web is sealed to -the associated cup around subs-tan-tially the entire peripheral flange thereo, leaving an unsea ed ' . . l -7~ :~
. ' .,' 1~5396 xegion adjacent an evacuation slit previously cut in the lower web; sïmultaneously, the upper web is selec-tively heated in regions which are subse~uently to be s-tretch-formed. In the second or ~inal seal statlon, the package is placed in a vacuum chamber and evacuated through the evacuation slit A~ter the start of evacuation, a plug, shaped to ma-tch the package top, is driven down z.gainst the upper web to force the previously heated and still soft and formable top closure : downward into the receptacle, stretching the film towards the product, preferably to the sur~ace of the product. Thereafter the evacuation slit is sealed off to complete the final seal of the package, and the upper par:t of the vacuum chamber is vented, advantageously to a pressure higher than atmospheric.
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It has been found tha~, in the machine to be descri~ ed, 15 : the composite of forces acting on the top closure will form the top film closely into conformity wlth the surface of the product, even though the product shape be substantially irregular. Moreover, the top film will be forced tightly intc : any depressions or poc~ets in the package interior. The result is a package with minimal distorting stresses or voids, and a ~ompletel~ encased and immobilized product with sharp definition of contours, providing a superior appearance.
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Other objects, aspects and advantages of t.he inven-tion will in part be pointed out in, and in part apparent ~rom ~5 the following description of preferred emhodiments~ considered together with the accompany.ing drawings.
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~L~g53~6 DESCRI.PTION OF rr'HE DR~WINGS
FIGURE 1 is a top plan view o:E packaging apparatus in accordance with this invention wherein product being packaged moves from right-to-left;
FIGURE 2 is a front elevation o~ the packaging apparatus of Figure 1~
. I .
FIGU~E 3 is a bottom plan view of the two-station packaging head of the machine, i.e. looking upwardly at it from underneath;
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FIGURE 4 is a perspective view illustrating -the progressive steps of the packaging material as it proceeds through the apparatus in accordance with this invention;
FIGURE 5 is a perspec-tive view of a completed. ~:
pac~age of round luncheon meat as it would be seen by the consumer, i.e. inverted from the way it would actually have passed th.rough -the packaging apparatus; .¦
FIGURE 6 is a vertical cross-section ta~en along line 6-6 of Figure 2 through the first station of the packagin apparatus and showing the first step of two packages being -formed simultaneously, side-by-side; . -. ~ -11119539~i FIGURE 7 is a vertical cross-section taken along line 7--7 of Figure 2 and showing the second sta-tion of the packaging apparatus; ~or convenience in Lllustration, the two s.ides of Figure 7 show different stages o~ the process carried out in the second station, with the stage on the right pre-ceding that on the left;
. ', FIGURE 8 is a vertical longitudinal section taken al line 8-8 of Figure l through both the first and second station , showing progression of the product through the packaging apparatus; 1 .. , . ,1.
FIGURE 9 is a section corresponding to Figure 7 but .
showlng the packaging apparatus being used for the packaying of frankfurters~ and with both plugs in the down position;
. . ~
FIGURE 10 is a detail vertical cross-section of a pa t I
of the second station showing a modification whereby the packa e ¦
!may be given an elevated base to better display its contents, . ' . 11 .
FIGURE 11 is a perspective view of the package which has been formed in the modification of Figure lO, inverted from the way the pacXage is shown in Figure lO. ,.
., .
FIGURES 1 through 8 illustra-te packaging apparatus in accordance with this invention used for the pacXaging of round sliced luncheon meat. FIGURE 9 shows a modified arrange-en-t used for packaging frankfurters.
I ' .
-- ~ gl~39S39~i DEq'AILED DES~RIP~ION OF PREE'ERRED EMBODI~ENTS
. ~ , ' ' . 1, Referring now to the right-hand por-tion of Fiyures and 2, a series o~ product-filled receptacle cups 20, pre-iously formed as side-by side pairs in a web 2~ of semi-rigid ~lastic film, are advanced from right-to-left in and through two-station pa~Xage-forming unit 24r This unit includes a ~ase 26 below the web line, and a packa~in~ head 28 above the ~eb line The base and head are supported by conventional ~¦
vertically-movable frames or beds (not fully shown~ ~driven in ynchronism to reciprocate the base and head in opposite ~ ;
~irections, i.e. to provide an opening and closing move~ent ~f those two parts. ~
: ' ~ ~ .
The web 22 is carried by~an edge-c-amp conveyor 30 ~riven with an intermittent indexing motion ln synchronism ~ith ~he reclprocating movement of the base 26 and head 28.
n a cycle of operation, starting from the closed position .hown in Figure 2, the base and head first are reciprocated part, the cups 20 then are lndexed forward one step into ~ ~ ~heir new position~between the base and head, and the base ~nd head then are moved back together into closed position as hown, surrounding t~e enclosed cups. Mechanisms for develop-ng the intermittent indexiny movement of the conveyor 30 are -ell ~now nd thus will rot be detailed here~n.
~ ll . . 1.
. . ll . ~ i ~53~
~ o the right o~ t'he package-formlng unit 24 an upper web 32 of ~ormable plastic film extends down cmd around a lay-do~n roll 34 which serves to apply the upper web over the receptacle cups 20 (see also Figure 4) befoxe the cups enter the package-forming unit As the upper web moves through the package-forming unit 24, it is sealed to the cups, and formed into closure tops which conform closely to the cup and product configurations~ The upper web is drawn from the usual supply roll, and is suEficiently wide to cover both cups of each side by~side palr, including the side flanges thereof. The uppex web 32 in the disclosed embodiment is of semi-rigid (5-15mil.) heat~formable plastic ~ilm with a coating of heat-sensitive peelable sealant compatible with the heat-sealing properties o the cup material. The packaging materials will h~ve predeter-~ined characteristics, such~as oxygen barrier, water vaportransmission rake, oxygen scavenging additives, etc., in ccordance wlth the partlcular product packaging requirements r : . ~ ' Referring now also to Figure 6, it will be seen that l n the first or "initial seal'~' station o~ the package-forming ~ni-t 24, the cups 20 are positioned in corresponding sealing d e ~avities forming par-t of the base 26~ These die cavities inol de ulti-part d~ fillers 38 shaped to match the cup configuration to provide firm support therefor. Surrounding each die avity is a temperature-resistant sealing bead 40 which, . .' `` ~`
~095396 when the packaging head 2~ has moved down to closecl posi.t:ion (as shown), is aligned ~.ith peripheral heat-sealing bars 42 o:E the head ~. These bars ex-tend around the three outer flanges of each cup and partially along t.he four~h flanges in the cen-tral region between the two cups. When the head descends into closed position, it presses the top closure film 32 and the cup flanges between the hot seal bars and the ..
sealing bead to effect a seal against air leakage part way around the cup mouth. The sealing bars are supplied with hea-t by electrical heating rods 44. .
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Af-ter the packaging head Z8 has moved down to engage the base 26, vacuum is developed ~as will be described) above the upper film 32 to draw that film upwardly and press it against a pair of side-by-side platens 46 (one for each cup 20) which are heated in selected regions by corresponding heating blocks 48. These blocks contai.n heater elemen-ts 49 and are separate from the heaters for the initial-seal bars -42. For round cups 20 to be used for flat produc.t tas shown), this platen is arranged to apply heat only to the regions o~
the upper web which are .just inboard of the corresponding i cup walls Thus, referring now to Figure 3, each platen ~ .
is.circular in outline, and comprises an outer heated band 50 (preferably formed with a slight concavity as shown in Figure ..
6~, and a non-heated circular heat-impeding insulator 52 .
~ 1095396 ~on-heated corner insulating members 54 also are positioned in the spaces a.round each platen 46 to minimize transfer o.~ heat to that part of the film, and to prevent d.istortion o~ the ~ilm which could result rom excessive film movement during the application of vacuum. A central insulat-ing member 56 is positioned between the -two platens to prevent : so~tening of the web in that region, so as to assure proper functioning of a web~ ter .in the next operating station as will be described. An insulator 58 (Figure 6) also is posi-: tioned between each heating block 48 and the outer parts of the head 28 to permit separate regulation of the temperatures of the heating blocks and the initial heat-sealing bars 4~.
On opposite sides o~ the central insulating member 5~
are~Einal-seal-area preheater regions 60 the operatlng surac s of which are contoured up a small dlsiance (e.g~ l/16") above ~ the plane of -the initial:heat-sealing bars 42. The insulator .
: I 56 is similarly contoured, as indicated by the break-line 59 :
: on Figur~e 3. The sealing bead 40 i5 interrupted in the area adjacent the preheaters 60 to prevent any inadvertent sealing wh~`~ch mlght obstruct air flow through this region during the subsequent evacuation o the package in the next stat.ion. .
Such preheating o~ the final seal area is particularly valuab e when making packages with semi-r1gid closures; reference may : be made to ~. S Patent 3,438,1~5, where this problem is dis-cussed, and means are described ~or positively pushing a top closure member against a preheater element by introducing air pressure into the package~
' -1~~' . '',''' ~s396 . i In the embodiment d~scribed herein, the top ~ilm 32 is moved up agains-t both the preheaters 60 and the platens 46 1 , b~ developing a vacuum above the top film 32. The achievement of desirably uniform vacuum is aided by the use of small vacuu~
orifices 70 drilled through the heating platens 4GD The vacuum also is applied through the gaps between -t~e platens and adJa-cent parts such as insulators and -the like.
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This vacuum is applied to the packaging head 28 through a valve-controlled vacuum port 72. The controL valve (not shown) for this port is synchronized with the machine operating cycle in such a fashion that vacuum is applie~ when the initial heat-sealing bars 42 contact -the upper webi 32.
The vacuum remains on during -the "dwell" portion of the indexing cycle, providing for transfer of the proper amount o~ heat to the upper web 32. The initial seal statlon then .is vented to atmosphere ~hrough its vacuum port 72, and the base 26 and head 28 are parted. When -~he base and head have moved su-fficiently -far apart, the lnde~ing cycle resumes, and t~e packages with their top closures now partially sealed to the cup 20, hea-ted sufficiently for forming b~ the heating platens 46, and preheated in the final seal areas, are trans-ferred to the next successive operating station where forming of the top closures will take place, along with evacuation an final sealing of -the packages.
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109539~
Referrin~ now -to FicJIl.re 7 5howiny -this E.inal-sea'l--and-evacuat:ion station wi-th t:he base 26 and -t~e pac~aginq heac' 28 closed, the cups 20 again are supported by appxopri.atel~
shaped multi~part die fillers 74. The base and head serve as clamps to press the packaging material together and to make air-tight sealing engagement with -the two webs oE packaging material so as to establish upper and lower vacuum chambers surrounding the partially-sealed packages~
The side walls 76 o the packaging head 2~ in the final-seal stat.ion are cooled by water passages 78 ad]acent the hori~ontal surfaces which press down against the previous-ly heat-sealed regions of the upper fLlm 32. This provides ¦
rapid chilling and setting of the heat~activated sealant serv ing to rninimize shifting or separation of the seal as a resul o~ stresses imposed on the seal areas during the s~sequen-t evacuation, forming, final sealing and venting operations yet to come in this station. This chilliny of the initial-seal areas is accompanied by squeezing of the package flange seals between the flat horizontal surfaces of the packaging head :20 side walls, and the flat elastomeric sealing surfaces B0 on the upper edge of the mating side walls 82 of the base 26~ :~
: The seal contours of this elastomeric sealing surface e~{tend 'a small distanFe outwardly beyond the initial seal area, i.e.
laterally outwards of that seal area. This overall arrangeme It develops an ironing action to provide the pacXage with a fla-t . undistorted ~lange superior in appearance and function to pacXages made by conventional means.
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-l~i- , ~9S3g~ 1 `
With the base 26 and pac~agi.ng head 2~ in closed position (as shown in Figure ~), a web-lifter 8~ is in known manner driven upwards throu~h a previousl~~formed evacuati.on slit in the lower web 12 to engage the l.ower surEace of the upper web 32 and raise that web up a small distance above the lower web. Such displacement of the upper web establishes large-capacity evacuatlon channels leading from the interior of each cup 20, through the as-yet unsealed region along the interior flanges of each cup, and down through the evacuation .
slit, the web-liEter bore 86, and the spaces beneath the d.ie fillers 74 to respec.ive conduits 88 coupled to the base 26 A control valve (not shown) Eor conduits 88 is actuated to apply vacuum to this evacuation channel, and the package evac uation begins.
. Simultaneously with the appllcation oE vacuum to conduits 88, a separate valve (not shown) is actuated to appl vacuum through a pair of conduits 90 to the upper vacuum cham ber, comprisLng the spaces above the upper web 32~ In certail ¦
aEplications, the web-lifter a4 may not be required for estab _ I
lishing -the evacuation channel leading to the cups 20, since I :
: when the spaces a~ove ths web 32 are evacuated, the initial internal air pressure within the package tends to force the upper we~ up, away from the lower web 22, for at least a por- . J
tion oE the evacuation cycle.
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1~ -1.7 ., ' .
., , I ',.
~L095396 ~ ~
. :tn any event~ when the spaces ou-tside o:E the packag ~s ¦
a:re e'vacuated, the air pressure ini tially in t.he package, i.e~ at the start of package evacuation,, produces forces on t'he packaging material pushing it outwardly in al L directions This develops s tresses which tend to cause dis tor tion in the package configuration. It has been :found to be important, for minimizing such distor tion of the cups 2 0, -to support the cups in die-fillers 74 of matched shape. The upper sur-faces of these fillers are in the same plane as the elasko-meric sealing surface 80 on the base side walls, in order to prevent distortion of the packaye flanges. This elastomeric sealing surface also is' extended at 92 into the evacuation s lit region to provide additional support :Eor the flanges in that region This extended surface tapers slightly downward as it approaches the evacuation slit to assure that the air can 10w from within the package without undue restriction .
: during evacuation. --It also has been found to be important to prevent the upper web 32 from moving a significant distance upwards 2 0 : above the web line during this period of posi tive pressure I . -differential within the package, in order to prevent stretchi lg I
~f the previously-heated film. In the region over the evac- t uation slit and the web-lifter 84, a fla-t restraining e'lement i, 94 is fixed in position to restrict the upward web movement of the closure film. The distance between -the :Eilm ana this :-..
~1095.~96 restraininy element is about l/lG'` to allow t~e web to r.ise only enough for rapid evacuation and optional gassing oE the ~ackage interio.r. This restraining element desirably is forme of heat~insulating material to prevent the upper web 32 from labsorbing excess heat rom a final seal bar 112, to be describ~ld ~ereinbelow, which is di.rectly over the interior flanges adja-~en~ fLnal seal areas.
Upward movement of the web 32 also is restricted by th~
lat surfaces of a pair of vertically movable, top-orming plu s 00 to be described below, and by the flat surfaces of insulat ng filler inserts 102 surrounding those plugs~ (~ote: The et-hand plug is shown in its down position, for convenlence f illus-tration, but i-t will be understood that both plugs mov : p and aown together, and that both plugs are in their upper osition as package evacuation beglns.~ When the plugs are in ~heir upper posLtion,-their lower suraces, and the su:rfaces o he insulating insert 102, may be within 1/32" o the surace the upper web 32. ...
.' Preerably the elements touched by the uppeF web 2, as it is forced upwards, are made of hea-t-insulating mate-ial, at least in the regions thereo which are opposite film reas heated in the preceding station, in order to avoid xcessive loss of heat from the film so as to maintain the Eilm at formable temperature. For especially long evacuation ycles, or or use with films which require additional heat o maintain a formable temp~rature, it may be des:irable to add pl~g heater, such as one u~ilizing conventional tubular elem~nts illustrate~cl at 10~ (shown onl~ or the le~t hand plug ¦
The plug heaters would transfer heat by conduct:ion to th~
movable plugs made in this case o:E a heat-conducti.ve materia:L
such as aluminum, and having a high-temperat:ure plastic releas ?
5 ~ coating (e.g. Teflon) on their lower sur~aces. Desirably, the plug mechanisms are insula-ted from the outer chilled surfaces of the head 28 by means of flat insulators 106.
i Turning now to the operation of the top-forming plug 100, when the evacuation of the packages is well underway and approaching completion, the plugs are driven downwardly by the vertically-reciprocable shafts 108 of respective air-operated c~linders 110. These cylinders are controlled ~y air-valves ¦(not shown synchronized with the machine operatiny cycl~ Th~
descending motion of the plugs stretches the previously heated and still soft and formable, top closure fllm 32 down into each cup 20 and towards the product therein. The downward movement o~ the plugs 100 also aids in rapid evacuation of the packages~
.
Satis-factory functioning can be achieved by driving the film 32 down to within a srnall dis-tance from the top of the product. However~ maximum corner definition and elimina- ¦
tion of substantial distorting residual stresses in the pacXag~
are obtained by stretching -the film all of the way down to the , surface of the product. The stroke depth is adjustable by means of nuts 109 limiting -the downward motion, and an anti-rotation arrn 111 also is provided.for use with non-round plugs v~ a f~ e ~2r~
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- ~953~
Preferably, the plugs are formed with sharply rad.iused side edges shaped -to closely conform to the cup sidewall perim-eter, e.g within 1/32", so that the side walls of the ~ormed tops desirably are in very close proximity to the side walls o.
the cups. The pluy shape may however va:ry acc~rding to the di~ len-sions and special requirements of the package and the product.
The plugs thus advantageously are arranged for easy interchang _ ability as by -the use of a simple fastener to hold them in pla, e.
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After the plugs have reached -the ends o~ their stroke, and evacuation is complete, a ~inal seal is made in the previ-ously unsealed regions along the adjacent interior cup flanges This is accomplished by a heated final-seal bar 112 which is I .
driven down by an air-operated act~ator. 114 to press against ¦ :
the upper web 32 with an appropriate degree of pressure. This .. I
seals the two webs toge-ther to complete the seal along the . ~.
entire periphery of the ~flanges surrounding each cup mouth.
Thereafter, the control valve for the upper conduits 90 is activated.to apply air under pressure to the pac~aging I .
: . head 28. Thus the spaces above the evacuated pac.kages are pressurized to a level above atmospheric pressure. The down- ~.
ward force of this air pressure, acting in combination with the stretching force of the plugs 100, stil3. held in their lower position, completes the proper forming of each top closu by pressing the still-heated ~ilm 32 intimately and tightly down again~t the surface o~ the product, so as to follow closely its contour or profile including any pockets or voids.
5:~g~
¦iTherea~ter, the upper and lower chambers are ventea to atmo-sphere, the base 26 and packaging head 28 are separated, and ¦the pac~ages are indexed out of the packaging head The com-!pleted packa~es are desirably free from distorting stresses o S ~voids, and the contained products are held immobilized with clear definition of their contours.
I . ~' The description above relates to the formation of a straight vacuum package. In some cases, it is desired to ~orm a gas package, i.e. a package having a small amount of gas her me~ically sealed therein, especially iner-t gas. The machine described herein can readily make gas packages, with minor changes to the package-forming procedures as set out below.
As in the process for making straight vacuum package , the upper web 32 first is selectively heated in the ini~ial seal stage as described, and then is transferred to the final seal stage ~or in-place ~orming of the tops and co~pletion of the packages. In the final seal stage, the initially-sealed pacXages are evacuated through the evacuation slit with the aid of the web-lifter 84, and the valve controlling the lower conduits 88 then is shut o~f. Thereafter a selected gas is supplied through an internal passageway in the web-lifter I -84 (in accordance with known techniques) into the package interiors. ~f-ter a predetermined amount of gas has been admitted, the final seal bar 112 descends from above the web 32 to complete the heat sealing of the packages. As ~ . 1, lOg539~
beEore, this final seal ~oins the preliminary seal lines to make a comple-te hermetical seal around the entire periphery of the flanges around the cup mouth. .
.
With the package compl.etely sealed, the plugs 100 descend and press the upper web 32 down towards and against the packaged product, compressing the gas previously admitted to the package and thus increasing its concentration, As the plugs reach the limit of their travel, the upper vacuum cham-. ber is vented, as b~ means of a three-way valve~(not sh~wn) in the conduit lines 90, to connect a regulated source of air pressure to the upper chamber. This inrush of pressurized . air above the web 32, which has already been mechanically s-tretched and somewhat formed by the plugs 100, serves -to .
force the warmed, formable film down into the cups 20', agains :15 the side walls of the cups, in-to any side wall cavities forme in the~cups, and down over the product in the cups, around -th contours thereof, until the pressure of the gas in the packag is equal to the pressure of the air supplied to the upper chamber. At this stage, the top web 32, being held down b~
the plugs 100, and forced against the product and cup, is chilled as it contacts the product and cup, and holds its for and contours, matching those of t~e product and other element against which it has been pressed.
The lower the pressure of the ga5 introduced into the package .relative to the air pressure used to vent the upper chamber, the more closely -the top closure film will . . ,.
~~_ l fol ow tho contours o~E the proauct: and the cup. The action of the plugs 100, however, in stretching and forcing the -top closure film down in-to the cup i5 independent of -these vari-ables and thus provides a top film forma-tion superior to tha-t obtainable by conventional means. The physical stretching of the in-terior marginal portions of the top film inwardly aroun the product and outwardly to the cup 20, especially to a permanent set dimension, is desirable be~ause it tends to eliminate any substantial build-up of tension in the film.
., i .... -The film is formed to folIow the contours of the c lp, and the force of atmospheric pressure is carried essentially by the pac~aged product, aided by the internal gas pressure.
This avoids placing portions of the package under heavy stresses, and minimizes dis-tortion of the cup, whether flexible or semi-rigid (as in the preferred embodiment~, from its original shape. The plugs 100 remain in their down position during venting of the top chamber, and if the plug face is ligh-tly pressing ayainst the product, this pressing o~f the -top film on-to the product will have the added bene-ficial effect of immobilizing the product without distortion 1, while the product and cup are subjected to the venting pressu e forces previously referred to.
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10~53g6 A~ter the top film 32 has chi.lled, the lower chamber is vented to atmosphere, the pluqs 100 are retrac-ted, the base 26 and the packaging head 28 separate, and the air pressure to the upper chamber is cut o~f. The conveyor 30 indexes forward one more step, and the procedures developed .
are xepeated.
It has been found thatmax~mum shaping of closure to product and cup is obtained w1th a vacuum package as the differential pressures between the package interiox and above t~le closure are maximized. Under these conditions, the heate formable closure film 32, driven by the plugs 100 and acted OI .
by the difEerential pressure resulting from vacuum. in the package and posi-tive ai.r pressure in the upper chamber,vill .
orm closely and intimately into and around the contours o tl .e product, and the cup, to produce a package of supexior appearance.
.' . ., One o~ the important virtues o~ -the pac~aging appa-ratus described is its flexible adapta~ility to a vaxiety of -packaging requirements. Probably of most siynificance in thi .regard is that the apparatus will produce packages the tops of which are automatically confo.rmed to differing contours ~or pro iles without r-quiring any changes in the apparatus ~ ~ S3~ 1 to accomodate such product variations This adaptability is a consequence o~ the fact that the closure top i.s ~ormed, while s-till warm, in such a manner that it is shaped by the prod~ct, ra-ther than being shaped by a specific~ prese-t die, or the like, designed to approximate an average product con- ..
tour. This advantage of the invention is not best demonstrate d by the illust~ated package of sliced bologna, since the top surfaces of bologna are relatively smooth, but would be bet-ter exemplified by the packaging of irregular products~
In addition, the descr-ibed apparatus can readily be .::
altered, by relatively simple change-over of parts, to shift from the packaging of one type of product to a quite different product. This is illustrated for example by Figure 9 which ic comparable to Figuxe 7 but shows the final seal stage arrangec for packaging frankfurters rather than bologna.
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In the modified machine of Figure 9, the plugs lOOA
ha~re a rectangular plan configuration matching ~he shape of a l rectangular cup 20A carrying the fran~furters. In the corre-sponding initial seal stage ~not shown), the upper web 32 is selectivel~ heated throughout a rectangular area opposite the rectangular mouth o~ the CUp, to soften that entire region of the upper web for forming in the final seal stage.
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. ,' ---`` ~L~953916 rrhe pr-ocedures fo:llowed :ln the :Einal stage ~re l:ike -t:hose previously described. The p~ckage evacuation f:irst .is initiated, and shortly thereafter the plugs lOOA are driven down to stretch the heated rectangular film area su~stantiall~
to the upper surfaces of the ~rank:Eurters. Final sealing of -the package then takes place, ater which the upper vacuum chamber is vented to positive pressure, i.e. above a~mospheric , while the plugs remain down and vacuum is maintained in the lower chamber. The positive pressure forces the still-heated film down around the side of the frankfurters (as illustxated in the left-hand unit), to follow the contours thereof closel~ -The resul~ing package thereby présents a sharpl~ defined, rigialy immobilized product, without dis-tortion, and clearly visible to a prospective customer. j : . .
Figures 10 and 11 illustrate the formation of still ano-ther type of package, wherein round bologna is held in a :~
specially-shaped receptacle 2QB providing a square platform or pedestal 120 between the package flanges 122 and the round , product-containing portion 124. To develop this two-level configurationy the top-forming plugs lOQB are shaped in a stepped arrangement, comprising a lower round portion I26 to match and fit within the round section o t~e receptacle, a~d an upper square portion 128 to match and fit within the corresponding square pedestal section of the receptacle As in the pre~ious embodiments, these plugs are driven down against the selectively-heated upper web 32 and serve, ~ ~ 10~15336 especi~lly in coIIjunction wl-th the pressure d:iE:Eerenti.al from ~the subse~uent venting of the upper char~er, to -Eorm the closure top in such a way that, as shown in Figure 11, .i.t provides a round section 130 and a square section 132 pre-1 cisely matching the receptacle shape and product configuratiorAlso, as in the Figure 6 arrangement, the pre-heating pla-tens in the initial seal stage will be so constructed as to selec~
Lively heat particularly those regions a:E the upper we~ which are to be stretch-formed in the final seal stage, so as to 10. produce the package as shown~
. ,~' It will be understood from the a~ove descrip-tion o preferred embodiments of the invention that apparatus followi the teachings of thls .invention is especially adapted to afford Elexible and versatile operation in producing excellen packages for products of various shapes and configurations. ¦
The invention finds special applicability for use with produc s o~ irregular shape, since with the unique top-~orming proce-dures described, the product itself controls the contour of th~ top closure. Thus, even though the product profi1e chang from unit to unit as they enter the machine, each closure top will automatically be conformea to its corresponding product. .
The apparatus also has the capability of making packages from a variety of different packaging ma-terials, in-cluding flexi~l.e and semi-rigid packaging ma-terial, plastic o -2~-o-therwise, whe-ther used for -the receptacle cup (lower web~ or the closure top (upper web). The versatility of the apparatu is still further enhanced b~ the ready interchangeability of the basic operating cornponen-ts so as to suit different types o:E products and/or package configurations. Such changeover in the preferred embodiments disclosed does not re~uire sub-stitution of a complete series of receptacle-supporting tra~s since bo-th webs of pac~aging material are supported by an ,.
edge-clamp conveyor adaptable to all kinds of packages Also although an intermlttently-indexed conveyor is shown, it will be appreciated that continuous-motion operation can be used, in accordance with well-known techniques.
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Accordingly, although specific preferred embodiment of the invention have been described in detail hereinabove, it is desired to e~phasize that ~his is for the purpose of illustrating the principles of the invention, and should not nec~ssarily be constru.ed as being limiting of the invention since it is.apparent that those skilled in this art can make ~ many modified arrangements of the disclosed apparatus wikhout departing from the true scope of the inven-tion~
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~E CL~
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Claims (26)
1. Packaging apparatus for making vacuum or gas-filled packages, comprising:
first and second packaging stations;
conveyor means for carrying a series of flanged cups into said second station, said cups containing products with upper surfaces thereof below the cup flanges;
means to supply a web of packaging material for move-ment through said first and second station with said web being positioned over said cups in said second station to serve as closure tops therefor to define packages;
heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;
vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber being shiftable from open to closed condition to evacuate said packages;
plug means in said second station;
drive means operable after said chamber has been closed for evacuation, said drive means serving to move said plug means relative to said vacuum chamber down against said heated web to stretch-form that web down into the interior of the correspond-ing cup, said plug means serving during evacuation of said chamber to force said web to a position at least immediately adjacent the upper surface of the product across substantially the entire upper surface thereof; and
1. cont.:
means to pressurize at least substantially to atmos-pheric pressure the portion of said vacuum chamber above said web of packaging material to complete the formation of said closure top by developing a tightly-fitted, substantially void-free product-engaging contact between said web and said product.
means to pressurize at least substantially to atmos-pheric pressure the portion of said vacuum chamber above said web of packaging material to complete the formation of said closure top by developing a tightly-fitted, substantially void-free product-engaging contact between said web and said product.
2. Apparatus as in Claim 1, including adjustable means to drive said plug means into the cup interior to the extent that the closure top reaches the adjacent surface of the product.
3. Apparatus as in Claim 1, wherein said vent means is operable while said plug means is maintained in position holding said closure top stretched down into the cup.
4. Apparatus as in Claim 1, wherein said vacuum means is operable to begin evacuation of said package prior to the actuation of said plug means to stretch-form said closure top down into said cup.
5. Apparatus as in Claim 1, including planar heat-insulating means in said second station located closely above the plane of said web to prevent significant upward movement of said web during the evacuation of the package.
6. Apparatus as in Claim 5, wherein said insulating means includes the planar surface of said plug means.
7. Apparatus as in Claim 1, including means to heat said plug means so that heat is transferred to said upper web as it is stretched down into the cup.
8. Apparatus as in Claim 1, wherein said first station comprises a heated platen; and vacuum means for drawing said web into contact with said platen to transfer heat to said web.
9. Apparatus as in Claim 8, wherein said vacuum means comprises holes through said heated platen.
10. Apparatus as in Claim 8, wherein said conveyor means carries said cups into said first station together with said web of packaging material;
initial heat-seal means in said first station; and means to thermally isolate said initial heat-seal means from said heated platen.
initial heat-seal means in said first station; and means to thermally isolate said initial heat-seal means from said heated platen.
11. Apparatus as in Claim 1, wherein said vent means is operable to provide positive pressure to said web.
12. For making vacuum or gas-filled packages of the type wherein a film of packaging material, sealed to a flanged cup of packaging material containing the product, is stretched to extend into the cup in telescoping fashion to tightly grip the product within the cup; the improved method comprising the following steps:
heating the film in regions thereof to be stretched into the cup;
placing the heated film and the cup in a vacuum cham-ber with the film overlying the cup flanges and the cup mouth to define a complete package;
closing said chamber to seal the interior thereof from outside atmosphere;
applying vacuum to said chamber and the interior of said package to initiate evacuation thereof;
after initiating evacuation of said sealed chamber and package, moving a plug against said film while it is still hot, to stretch-form the film down into the cup to a position at least immediately adjacent the upper surface of the product therein substantially over the entire upper surface thereof;
before or after said movement of said plug, sealing said package material to provide a complete hermetic seal of said package; and pressurizing said vacuum chamber above said film to at least substantially atmospheric pressure while said plug is pressed against said film, the pressure forcing said film tightly against the product in said cup to effect close, intimate and essentially void-free contact therebetween.
heating the film in regions thereof to be stretched into the cup;
placing the heated film and the cup in a vacuum cham-ber with the film overlying the cup flanges and the cup mouth to define a complete package;
closing said chamber to seal the interior thereof from outside atmosphere;
applying vacuum to said chamber and the interior of said package to initiate evacuation thereof;
after initiating evacuation of said sealed chamber and package, moving a plug against said film while it is still hot, to stretch-form the film down into the cup to a position at least immediately adjacent the upper surface of the product therein substantially over the entire upper surface thereof;
before or after said movement of said plug, sealing said package material to provide a complete hermetic seal of said package; and pressurizing said vacuum chamber above said film to at least substantially atmospheric pressure while said plug is pressed against said film, the pressure forcing said film tightly against the product in said cup to effect close, intimate and essentially void-free contact therebetween.
13. The method of claim 12, including the step of admitting a gas into the package interior after the package has been evacuated;
thereafter hermetically sealing said package; and thereafter moving said plug against said film.
thereafter hermetically sealing said package; and thereafter moving said plug against said film.
14. The method of Claim 12, wherein said plug is moved against said film prior to the hermetic sealing of said package and while said package is being evacuated, whereby the plug movement aids in evacuation of the package.
15. The method of Claim 12, wherein said plug movement begins after start of evacuation of the package.
16. The method of Claim 12, wherein said plug is moved a distance sufficient to stretch said film into contact with said product.
17. The method of Claim 12, wherein said vent pressure is above atmospheric pressure.
18. The method of Claim 12, including the step of trans-ferring heat to said film during said plug movement.
19. The method of Claim 18, wherein said heat is trans-ferred to said film from said plug.
20. For making gas-filled packages of the type wherein top film of packaging material is sealed to the flanges of a cup and the central regions of the film are stretched down into the cup interior to press against the upper surface of the product; the improved method comprising:
positioning the film over the cup in the plane of the cup flanges to define a package structure;
evacuating said package structure and the spaces therearound;
admitting a predetermined amount of gas into said package structure;
hermetically sealing said film to said cup to make a complete package;
moving a plug against said film to force its central region into said cup to a position adjacent the product in the cup, thereby compressing the gas in the package; and applying fluid pressure to said film to press that film tightly against said product.
positioning the film over the cup in the plane of the cup flanges to define a package structure;
evacuating said package structure and the spaces therearound;
admitting a predetermined amount of gas into said package structure;
hermetically sealing said film to said cup to make a complete package;
moving a plug against said film to force its central region into said cup to a position adjacent the product in the cup, thereby compressing the gas in the package; and applying fluid pressure to said film to press that film tightly against said product.
21. The method of Claim 20, wherein said fluid pressure is developed by venting the spaces above said film.
22. The method of Claim 21, wherein said spaces are vented to a pressure above atmospheric.
23. Packaging apparatus for making vacuum or gas-filled packages, comprising:
first and second packaging stations;
conveyor means for carrying a series of flanged cups into said second station, said cups being formed with a predeter-mined plan configuration closely matching that of a product carried by the cup and having upper surfaces below the cup flanges;
means to supply a web of packaging material for movement through said first and second stations with said web being positioned over said cup in said second station to serve as closure tops therefor to define packages;
heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;
vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber being shiftable from open to closed condition to evacuate said packages;
plug means in said second station;
drive means in said second station operable after said chamber has been closed and during evacuation thereof to move said plug means forcibly down against said heated web to stretch-form that web down into the interior of the corresponding cup;
said plug means being formed with a plan configuration matching that of said cups and presenting a contact area at least substantially coextensive with the upper surface of the product in the cups so as to extend out laterally essentially to the side edges of said product adjacent the side walls of the cup;
adjustable means to control the depth of penetration of said plug means into each cup such that said web is forced down essentially substantially to the upper surface of the contained product; and means to pressurize at least substantially to atmospheric pressure the portion of said vacuum chamber above said web of packaging material so as to complete the formation of said closure top after initial formation thereof by said plug means.
first and second packaging stations;
conveyor means for carrying a series of flanged cups into said second station, said cups being formed with a predeter-mined plan configuration closely matching that of a product carried by the cup and having upper surfaces below the cup flanges;
means to supply a web of packaging material for movement through said first and second stations with said web being positioned over said cup in said second station to serve as closure tops therefor to define packages;
heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;
vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber being shiftable from open to closed condition to evacuate said packages;
plug means in said second station;
drive means in said second station operable after said chamber has been closed and during evacuation thereof to move said plug means forcibly down against said heated web to stretch-form that web down into the interior of the corresponding cup;
said plug means being formed with a plan configuration matching that of said cups and presenting a contact area at least substantially coextensive with the upper surface of the product in the cups so as to extend out laterally essentially to the side edges of said product adjacent the side walls of the cup;
adjustable means to control the depth of penetration of said plug means into each cup such that said web is forced down essentially substantially to the upper surface of the contained product; and means to pressurize at least substantially to atmospheric pressure the portion of said vacuum chamber above said web of packaging material so as to complete the formation of said closure top after initial formation thereof by said plug means.
24. Apparatus as in claim 23, wherein the lateral dimensions of said plug means are substantially equal to the interior dimensions of said cup, to provide that the top as formed by said plug means extends out immediately adjacent to the inner side walls of the cup;
said plug means being formed at the sides thereof with sharply radiused edges to contact said web and provide sharp contours for the top.
25. For making vacuum or gas-filled packages of the type wherein a film of packaging material, sealed to a flanged cup of packaging material containing the product, is stretched to extend into the cup in telescoping fashion to tightly grip the product within the cup; the improved method comprising the following steps:
heating the film in regions thereof to be stretched into the cup;
placing the heated film and the cup in a vacuum cham-ber with the film overlying the cup flanges and the cup mouth to define a complete package;
closing said chamber to seal the interior thereof from outside atmosphere;
moving a plug against said film while it is still hot;
while said plug is moving against said film, apply-ing vacuum to said chamber and the interior of said package to effect evacuation thereof;
continuing the movement of said plug to stretch-form the film down into the cup to a position at least immediately adjacent the upper surface of the product therein, substantially over the entire upper surface thereof;
before or after said movement of said plug, sealing said packaging material to provide a complete hermetic seal of said package; and pressurizing said vacuum chamber above said film to at least substantially atmospheric pressure while said plug is pressed against said film, the pressure forcing said film tightly
said plug means being formed at the sides thereof with sharply radiused edges to contact said web and provide sharp contours for the top.
25. For making vacuum or gas-filled packages of the type wherein a film of packaging material, sealed to a flanged cup of packaging material containing the product, is stretched to extend into the cup in telescoping fashion to tightly grip the product within the cup; the improved method comprising the following steps:
heating the film in regions thereof to be stretched into the cup;
placing the heated film and the cup in a vacuum cham-ber with the film overlying the cup flanges and the cup mouth to define a complete package;
closing said chamber to seal the interior thereof from outside atmosphere;
moving a plug against said film while it is still hot;
while said plug is moving against said film, apply-ing vacuum to said chamber and the interior of said package to effect evacuation thereof;
continuing the movement of said plug to stretch-form the film down into the cup to a position at least immediately adjacent the upper surface of the product therein, substantially over the entire upper surface thereof;
before or after said movement of said plug, sealing said packaging material to provide a complete hermetic seal of said package; and pressurizing said vacuum chamber above said film to at least substantially atmospheric pressure while said plug is pressed against said film, the pressure forcing said film tightly
25. cont.:
against the product in said cup to effect close, intimate and essentially void-free contact therebetween.
26. Packaging apparatus for making vacuum or gas-filled packages, comprising:
first and second packaging stations;
conveyor means for carrying a series of flanged cups into said second station, said cups being formed with a predetermined plan configuration closely matching that of a product carried by the cup and having upper surfaces below the cup flanges;
means to supply a web of packaging material for movement through said first and second stations with said web being posi-tioned over said cups in said second station to serve as closure tops therefor to define packages;
heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;
vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber comprising first and second mating components which are relatively shiftable from open to closed position to evacuate said packages;
plug means in said first component of said vacuum chamber and mounted for movement relative thereto towards and away from said packages;
drive means in said second station operable to move said plug means relative to said first chamber component and forcibly down against said heated web to stretch-form that web down into the interior of the corresponding cup;
against the product in said cup to effect close, intimate and essentially void-free contact therebetween.
26. Packaging apparatus for making vacuum or gas-filled packages, comprising:
first and second packaging stations;
conveyor means for carrying a series of flanged cups into said second station, said cups being formed with a predetermined plan configuration closely matching that of a product carried by the cup and having upper surfaces below the cup flanges;
means to supply a web of packaging material for movement through said first and second stations with said web being posi-tioned over said cups in said second station to serve as closure tops therefor to define packages;
heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;
vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber comprising first and second mating components which are relatively shiftable from open to closed position to evacuate said packages;
plug means in said first component of said vacuum chamber and mounted for movement relative thereto towards and away from said packages;
drive means in said second station operable to move said plug means relative to said first chamber component and forcibly down against said heated web to stretch-form that web down into the interior of the corresponding cup;
26. cont.:
said plug means being formed with a plan configuration matching that of said cups and presenting a contact area at least substantially coextensive with the upper surface of the product in the cups so as to extend out laterally essentially to the side edges of said product adjacent the side walls of the cup;
adjustable means to control the depth of penetration of said plug means into each cup such that said web is forced down essentially substantially to the upper surface of the contained product; and means to pressurize at least substantially to atmospheric pressure the portion of said vacuum chamber above said web of packaging material so as to complete the formation of said closure top after initial formation thereof by said plug means.
said plug means being formed with a plan configuration matching that of said cups and presenting a contact area at least substantially coextensive with the upper surface of the product in the cups so as to extend out laterally essentially to the side edges of said product adjacent the side walls of the cup;
adjustable means to control the depth of penetration of said plug means into each cup such that said web is forced down essentially substantially to the upper surface of the contained product; and means to pressurize at least substantially to atmospheric pressure the portion of said vacuum chamber above said web of packaging material so as to complete the formation of said closure top after initial formation thereof by said plug means.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US82208877A | 1977-08-05 | 1977-08-05 | |
US822,088 | 1977-08-05 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1095396A true CA1095396A (en) | 1981-02-10 |
Family
ID=25235103
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA307,995A Expired CA1095396A (en) | 1977-08-05 | 1978-07-24 | Packaging apparatus and techniques for forming closure tops |
Country Status (3)
Country | Link |
---|---|
JP (1) | JPS5449289A (en) |
CA (1) | CA1095396A (en) |
DE (1) | DE2834076A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS62271806A (en) * | 1986-05-14 | 1987-11-26 | 大森機械工業株式会社 | Method of packaging package with annular reinforcing rib |
JP2001192003A (en) * | 2000-01-13 | 2001-07-17 | Prima Meat Packers Ltd | Food packaging container |
DE102010019720B4 (en) | 2010-05-07 | 2014-01-02 | Multivac Sepp Haggenmüller Gmbh & Co. Kg | Method for operating a packaging machine |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3061984A (en) * | 1959-09-25 | 1962-11-06 | Reid A Mahaffy | Packaging machine and method |
US3438175A (en) * | 1965-02-01 | 1969-04-15 | Mahaffy & Harder Eng Co | Automatic packaging apparatus |
US3545163A (en) * | 1969-07-30 | 1970-12-08 | Mahaffy & Harder Eng Co | Package forming methods and apparatus |
DE1939216C3 (en) * | 1969-08-01 | 1975-06-12 | Kraemer & Grebe Kg, Maschinenund Modellfabrik, 3562 Wallau | Device for venting and gassing packs |
US3792181A (en) * | 1969-09-24 | 1974-02-12 | Mahaffy & Harder Eng Co | Semi-rigid plastic package with reclosable seal |
US3972155A (en) * | 1969-09-24 | 1976-08-03 | Mahaffy & Harder Engineering Company | Packaging techniques for semi-rigid packages |
US3695900A (en) * | 1970-07-22 | 1972-10-03 | William E Young | Evacuated hermetically sealed package with semirigid shell and stretchable closure |
CA1002442A (en) * | 1972-01-12 | 1976-12-28 | Mahaffy And Harder Engineering Company | Continuous movement packaging machine |
US3805486A (en) * | 1972-05-31 | 1974-04-23 | Mahaffy & Harder Eng Co | Packaging apparatus and techniques |
JPS5848412B2 (en) * | 1975-05-06 | 1983-10-28 | 凸版印刷株式会社 | Vacuum sealing method and device for containers |
-
1978
- 1978-07-24 CA CA307,995A patent/CA1095396A/en not_active Expired
- 1978-08-03 DE DE19782834076 patent/DE2834076A1/en active Granted
- 1978-08-04 JP JP9534678A patent/JPS5449289A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
JPS5449289A (en) | 1979-04-18 |
DE2834076C2 (en) | 1990-12-20 |
DE2834076A1 (en) | 1979-02-15 |
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