Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR PACKAGING FOOD
This invention relates to m~chinPs for parl~ging food products and related methods. In
one embo 1imPnt the p~ gP~ product may be ~ ~1 in one condition under certain
P~ and then converted to another co~ition For eY~mp1e, during l~ s~ll~tion the
5 food p~c~ge might ",;.in~ an inert gaseous ~tmo~rhPre and then, when the p~rL~e reaches a
s~ .k-l or other retail outlet, the food parl~ge will permit ~ JO:~Ule of the food product to
the ~mhient ~tmosrhPre. While a wide variety of food products can be p~c~gPd in accordance
with the tP~-hings of this invention, it is particularly advantageous in c~ ~;l;o.- with the
p~rk~f~ing of meat in a m~riifiPd atmosphere package such that the meat may be L~dns~olled in a
10 relatively inert atmosphere and then caused to bloom when it reaches a retail outlet by exposure
to oxygen.
~ i~t~rir~11y, meat products have been butchered and p~r~ed in each su~~ t or
other retail outlet. It has long been recognized that this arrangement is extremely inPffl~i.ont and
15 expensive. Tn~tP~l, it would be pl~r~l~ble to permit the meat to be butchered and packaged at
an Pffi~iPnt facility which benefits from economies of scale and thereafter to be shipped to
individual :~U~ l k~tc or other retail outlets.
In the past, this desirable goal has riot been achievable because most consumers prefer to
2o buy meat which is red in color as a result of exposure to oxygen. However, the meat .Il~ in~
its red color for only one to two days. Thereafter, it turns to a purple color which is nndecir~hle
to most consumers. Therefore, if the meat was butchered and packaged in one location and
then shipped to another location for eventual sale, by the time the package reached the retail
outlet the meat would have undergone the transformation to the purple color and would be
2s effectively unsalable.
To overcome these problems, there have been a number of efforts to m~int~in the food
product in a first atmosphere during shipping and a second atmosphere when the meat product is
ready for retail sale. It is not believed that any of these techniques have yet achieved ~ignifi~ ant
commercial acceptance. Therefore, it is highly desirable to provide a package that would
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-- 2
permit remote meat ~lc~A~AI;~ n and subsequent sale after the passage of rnore than a couple of
days. It is equally ~le~ hle to have an a~dldLus and method for pAr~ Iping such pl~lu.;L~ in an
~.ffiri~nt and cost-effective way despite the fact that most con~nmPr.c would prefer not to invest a
large amount of money in ~ldboldL~ pAr~ges
Thus, it should be a~ t that there is a cu~ p- need to solve the l-~"~ p,
problem of providing a package which permits meat or other food products to be pAr~geA at
one lnr-Ati~n and then to be sold sometime later under dirr~ t c~n-lition~ One approach to
solving these problems which has shown con~i~lç~dble commercial promise is r~ osed in U.S.
Patent No. S,348,752 to Mi~'hrAPl P. C~orlirh In this patent, a depression is provided in the tray
which allows the cutting blade to cut plastic film from a web in place on a tray without
/1A I ~ ~AP i t-g the pArlr~ping-
It is very ill~lL~lt in pAr~ging applications, inrhllling the modified Al.--osl.h~e
15 pAr~ging, to cut pidStiC film reproducibly at high speeds. This means that the film not only is
cut very quickly, but that it is cut repe~t~-Aly in the exact same way, completely through the
film.
Plastic film has conventi~nAlly been cut by a vanety of blades which may include20 sPm~tPci snrf,lrçs which are pressed through plastic film to sever the film in place. These
systems require a suitable backing plate or anvil to receive the cutting blade. This is because
plastic films tend to be extremely flexible and moreover, are often quite elastic. Thus, plastic
films tend to flex and deform, and even stretch when cutting is ~LLe~ L~d. While cutting these
mAtPriAlc at relatively slow speeds does not tend to be a particular problem, the difficulties
2 5 intensify at higher speeds.
ConventinnAlly, plastic films are cut to fit on trays and other surfaces in convçntionAl
pArl~ging applications. Cutting the film to size within the confines of the tray has not been
alL~ Led because of the AhsPncP of a suitable support to receive the blade or because of the
30 likelihood that the blade would damage the package tray. Moreover, because it is often
=
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n~c~,y to cut a piece out of a plastic web, the web must be cut clean through all the way
around the closed cut.
While heated cutting blades are known in connF~ti- n with cutting and sealing plastic, the
5 I~ ;s utili~d co~ olld to plastic sealing Lelllpeldtules. Plastic is usually sealed at its
~r,~.-i.-g ~ ---t;. Thus, these heated blades are often fouled with so~Pned plastic and
must be cleaned regularly.
It would be highly desirable to have a severing system which cuts film either inside the
10 conl i~-Pc of a package or at p~ge edges in a rapid and reproducible fashion. Moreover, such
a system which does not require excessive c~lP~ning would be particularly desirable. While such
a system would have a variety of applications, it would be highly desirable to have a high spe d
plastic film severing system useful for severing plastic film for trays, inrlntling trays used for
modified atmosphere p~ ging
In accordance with another aspect of the present invention, a p~ ging method using a
plastic film cutting tool having a cutting blade includes the steps of heating a portion of the
blade to a tel~laLul~ sufficient to vaporize the film to be severed and cont~-ting the film with
the heated portion of the blade.
~ -
In accordance with yet another aspect of the present invention, a p~t~k~gin~ m~-hinP has
a cutting tool for severing plastic film. The m~-hin~ includes a heated cutting blade having a
blade tip heated by a heating Pl~om~nt ext~n~ling along its length. The cutting tool is adapted to
enable the blade tip to reach ~ n ~ ~ ~s in excess of 600~ F.
In accordance with still another aspect of the present invention, a p~-k~ging m~hin~
incl~ s an ~ p~UdLlls for cutting a film portion from a plastic film web. The apparatus has a
blade arranged in a ~5~ ti~11y closed geometrical shape, a heating ~-lPmPnt for heating the
blade, a m~h~nicm for moving the blade towards and away from the web to be cut, and a blade
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..... u.~ device. The device conn~ctC the mPrh~ni~"~ to the blade, and is adapted to permit
heat ~Yp~nci-~n of the blade relative to the mPrh~nicm
In acco,~lce with yet another aspect of the present invention, a p~rk~ging m~rhinP is
5 capable of supplying a desired p~rk~ginv gaseous envilun,,,el,l to a p~r~ge inrln-ling a tray and
a plastic film for covering the tray. The m~rhin~ inrl~ Ps a cha,-,beL having an upper housing
portion and a lower housing portion. The rh~mhPr is adapted to sealingly sandwich the plastic
film such that the ~li~llGly of the plastic film is rl~mped between the upper and lower housing
portions. A film clamp is ~r~ngPA to hold the film between s~lcceccive trays inside the
1 0 ~ " ,l ,t~,
In accordance with still another aspect of the present invention, a p~r~ging m~rhinP for
covering a plurality of trays with plastic film inchldec a conveyor for loading a plurality of trays
into the machin~ at one time. A pr~ mm~hle sensing device C~ PC the presence of a
15 desired l~u~b~r of trays on the conveyor, in position to be loaded into the machine. The device
is pl'~ h1P to adapt to dirrtlc;l,L tray sizes or different desired nllmhPrc of trays.
In accordance with another aspect of the present invention, a p~rk~ging m~rhinP for
covering trays with a plastic film inrlucles an apparatus for unloading the completed packages.
2 0 The unlo~riP-r inrlud~Pc a pusher arranged to push a plurality of the packages from the m~rhinP at
one time. The pusher is adapted to offset the pack~ages with respect to one another in the
direction the packages are ~licpl~reA
In accordance with yet another aspect of the present invention, a p~rk~ging m~rhine for
2 5 covering a plurality of trays with plastic film includes a conveyor for loading a plurality of trays
into said m~rhine A first stop is located to control the access to the m~chinp of the next tray on
the conveyor to be loaded. A second stop is located to control the access to the m~rhine of a
tray second in line to be loaded. A pusher is provided for pushing the next tray and the second
in line tray apart from one another.
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Figure 1 is a cross-s~tinn~l view taken gen.or~lly along the line 1-1 in Figure 2;
Figure 2 is a front elevational view of the embodiment shown in Figure l;
Figure 3 is an lonl~rf~ed top plan view of a portion of the embo limPnt shown in Figure
1, ~h~w~lg the loading area receiving trays to be packaged;
Figure 4 is a front elevational view of the portion shown in Figure 3;
Figure !j is a front elevational view corresponding to that shown in Figure 4 after a row
of trays has been po~itionP~i atop a receiving platform;
Figure 6 is a top plan view of the portion shown in Figure 5;
Figure 7 is a vertical, cross-sectional view partially broken away so as to show two
rather than four stations and with vacuum and gas supplying means removed;
Figure 8 is a view co~ ~nding to Figure 7 after the platform has been removed from
the rotary arrns;
:
Figure 9 is an enlarged, plan view of the quick disconnect tooling at the station 22a;
Figure 10 is an enlarged, cross-sectional view taken generally along the line 10-10 in
Figure 9;
Figure 11 is a partial, side elevational view of the unloading station;
Figure 12 is a partial, side elevational view of the unloading station after a platform has
been raised to an "up" position;
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Figure 13 is a top plan view of the embodiment shown in Figure 12 after the trays have
been pushed onto the nnlo~-ling conveyor;
Figure 14 is an enlarged, partial, cross-sectinn~l view of the bottom of the surge tank;
Figure lS is a cross-sectional view of an embodiment of the present invention taken
gen~.~lly along the line 15-15 in Figure 20;
Figure 16 is a cross-secti~-n~l view taken generally along the line 16-16 in Figure 20
10 ~ wil~g the movable blade support assembly with the seal bar removed;
Figure 17 is a cross-section~l view taken generally along the line 17-17 in Figure 20
showing the fixed blade support ~ mhly with the seal bar removed;
Figure 18 is a cross-s~ction~l view taken generally along the line 18-18 in Figure 16;
Figure 19 is an enlarged side elevational view showing the connection of a column to
the blade;
2 o Figure 20 is a cross-sectinn~l view taken generally along the line 20-20 in Figure 15;
Figure 21 is a top plan view of another embodiment of tray unlo~-1er;
Figures 22a and 22c are enlarged top plan views of another embodiment of a tray loader
2 s while Figures 22b and 22d are side elevational views of the tray loader;
Figure 23 is a top plan view of another tray loader with two trays ov~lla~ g;
Figure 24 is a side elevational view of the tray loader of Figure 23;
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7 _
Figure 25 is a top plan view of the tray loader of Figure 23 after the overlappe~d trays
havebeen~ A;and
Figure 26 is a side elevational view of the tray loader shown in Figure 25.
l?P-ff rring to the drawing v~h~ like l~r~lc"ce rh~r~rtt--r.C are used for like parts
Illruu~ ul the several views, a ~L;-~;Q~ m~rhine 20, as shown in Figure 1, inrlll(iec four
stations 22. While the m~rhin~ is illllstrAt~ in a four-station emboriim~nt it should be
lm~lrr~ctc~ that one or more of the inrlir~t~A stations may be unused and that in any particular
10 ~"~bodi~ent it may be possible or ~eci~bl~ to have more or less than four st~tinnc. The four
stations 22 operate on packages which are moved circularly from one station to the next.
The p~rL~es to be produced are held on a platform 24 which in the illllctr~t~
emboclim~nt inrllltles slots 26 to receive four package trays. A variety of p~rk~ge types may be
15 utili7~cl One type of package type uses a relatively rigid molded plastic tray which is covered
by either a film or an ~ liti-m~l plastic domed closure. Examples of packages of this type are
~icrlosf~l in U.S. Patent No. S,348,752 and copending patent applic~tion and 08/098,530, filed
July 28, 1993. Both the pending patent application and issued patent are hereby ~A~lc~s~ly
incorporated by reference herein.
The platforms 24 are calTied on mounting arms 28 which in turn connect to rotatable
ring 30. The ring 30 is driven by the merh~nicm 32 which may be of any conv.~ntion~l type but
is illl-s~ t~A as being a drive chain and motor arrangement.
The entire m~t~hine 20 is supported atop a base 34 on feet 36, as shown in Figure 2.
Base 34 also supports a surge tank 38, which in turn supports a hanger assembly 40. The surge
tank 38 provides a central support for mounting the ring 30 and drive mechanism 32. The base
34 and hanger assembly 40 may be utilized to support various equipment pocitinn~d at the
stations 22 for ~L;ldlil~g on the food trays contained within the platform 24. For example, as
3 0 shown in Figure 2, a tray load m~h~nicm 42 is ~c50ci~t~d with the station 22a and supported
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on the base 34. Simil~rly, a tooling assembly 44 inclllcles an upper portion 46 llluullL~d on the
hanger 40 and a lower portion 48 mounted on the base 34. The upper portion 46 inr~ c a
hnucin~ or ~'h,.."h~. 47 and the lower portion 48 inrlllcles a housing or rh~mhPr 49.
The tray load ~"~h~icm 42, shown in Figure 5, inrlll-les a tray conveyor 50 and a tray
loader 52. The conveyor 50 may be a convPntinn~l belt conveyor Wll~lC;ill the trays 55 are
motinnP1 onto the tray conveyor 50. They are aligned by a stop bar 54 powered by a cylinder
56. At the a~ uyl~le interval, the trays 55 may be advanced to a second stop bar 58 so that
the yO~LiOIl previously occupi~A by the trays 55 may be filled by ~ lition~l trays. The stop bar
0 58 is controlled by a second cylinder 60. The trays 55 may be pre-loaded with the food product
to be p~r~ A
Below the ~ldlrc,llll 24a, there is a cylinder 62 that powers a bed 64 upwardly and
downwardly. The bed 64 inr~udes a stop 66 on its inward end. Each bed 64 is ~ecignrA to
receive a tray !;5 from the tray conveyor 50 and to lower it into a platform slot 26. Thus, there
would be a plurality of m~h~nicmc 62 and 64, one for each of the slots 26 in a platform 24a.
In the illllctr~t~A emb~Ylim~nt the station 22b is an inactive station which is not used.
However, in the other applications, it may be desirable or ne~s~ry to perform all or part of the
2 o operation which is done at another station at the station 22b. The station 22b could be used, for
Py~mpl~P, to load the food product into the trays 55.
The station 22c inrhlcles a tooling assembly 44 made up of an upper portion 46 and a
lower yortion 48. As shown in Figure 2, the upper chamber 47 is mounted on a ml-rh~nicm 68
2 5 which allows it to be raised and lowered towards and away from the platform 24. Likewise, the
lower chamber 49 is mounted on a m--rh~nicm 70 which raises and lowers the lower portion 48
towards the underside of the platform 24. If desired, either the upper chamber 47 or lower
çh~mhPr 49 may be st~ti~,n~ry.
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g
The Illuulllillg of a platform 24 on the arms 28 is shown in Figures 7 and 8. As shown
in Figure 7, the pl~ffcnn 24 is mounted on the arms 28 by a plurality of ~~pst~n~ling pins 72.
- Each pin 72 inrll~ 5 a tapered upper portion 74 which fits in a mating tapered portion 76 in the
unrlP~ of the yldLrCIllll 24. Thus, the pldlr)llll 24 is removably located ûn the arms 28 by
5 way of the pins 72.
The lower ~ .h~ 49 inrluri~s a pair of upst~n-ling pins 78 with tapered portions 80
which mate in holes 82 in the platform 24. Thus, when the lower chamber 49 moves upwardly
to engage the platform 24, the tapered portions 80 of the pins 78 mate with the holes 82 in the
10 pldlrullll 24. In this way, the yldlr~llll 24 is very precisely centered and pocitionPd within the
station 22c. As shown in Figure 8, the lower d~alllbel 49 actually lifts the platform 24 off of its
pins 72 to achieve the precise ~lignmP.nt The upper chamber 47 and lower ~h~mhPr 49 contain
seals 84 which provide an air tight seal with the upper and lower surfaces of the platform 24,
again as shown in Figure 8.
The configuration of the upper and lower portions 46 and 48 of the tooling assembly 44,
shown in Figure 10, inrl~ Ps a sealer 86, a cutter 88, and a web winding system 90. The web
92 may be unrolled from a roll 94, ~,~ cessed inside the tooling assembly 44 and transferred to a
waste roll 96. The film 92 may be made of any plastic film used for food p~rl~ginginr.lllrling
COlllpO:ii~ films of plastic, aluminum foil, paper, or cardboard.
With the film 92 po.citionPIl over the tray 55, it may be sealed by the sealer 86 which is
mounted on a shaft 108. The seal bar may be telescopically reciprocated up and down at the
ay~r~liat~ times in order to seal the film 92 to the tray 55. A wide variety of sealers 86 may
25 be utili7pli~ however one convPntic-n~l sealer uses electrical recict~nce heaters 100 in order to
heat seal the film to the tray 55. The extent of upward and downward movement of the shaft
108 is controlled by the medial stops 102 under the influence of a conventional fluid energy
source. The medial stops 102 are part of a tube 98 which is sealing secured to the shaft 108.
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-- 10 --
The sealer 86 may be removed from the m~ch~ni~m for repair or c~ ning when desired
simply by ulllhl~;ad..lg the nut 106. When this is done, the shaft 108 and sealer 86 may be
removed downwardly from the ~ n;cm.
The cutter 88 inç.llldes a pair of blades 110 po~itioned to enter the recess 112 in the
l~lr.,..~ 24. These blades cut the film 92 completely around the upper cil.;ulllr~ ce of the
tray so that it c4llr~lllls to the configuration of the tray 55. Of course, any conv~ntinn~l
severing technique may be utilized in~ ling cutting or heat severing. Also, more than one web
or film may be severed for ~tt~hm~nt to the tray 55. Like the sealer 86, the cutter 88
~ lu~s upwardly and duwllwaldly around the sealer 86. It is controlled by stops 114 on
arms 116 under the infl~ .nr,e of a convPntion~l fluid energy source.
The cutter 88 also in~,ludes an internal coolant circulation passage 118. Connected to a
source of ~Yt~.rn~l cooling liquid, the passage 118 provides a medium for cooling the cutter 88.
The cutter 88, in close ~lU~UIlli~y to the sealer 86, is subject to possible heat related
malfi-n~finn.~ By cooling the cutter 88, the precision of the cutting operation may be
...~i..~;,i.~ even in a relatively hot envir~)nm.-nt
The lower chamber 49 cont~in~ a gas exchange passage 130 in its lower surface, while
the upper chamber 47 incllldes a gas exchange passage 132 in its side wall. The lower portion
48 may include filler 134. Each platform 24 includes a plurality of gas exchange passages 136.
The gas eYçh~nge passage 132 comml-nic~tes with a vacuum source by way of the quick
~li$rnnnfY~t device 138, shown in Figure 9. That device is secured to the upper chamber 47 by
threaded knobs 140. ~imil~rly, device 142 is connected by threaded knobs 144 to lower
~h~mh~-r 49 to provide gas ~oY~çh~nge via opening 130.
Referring to Figure 9, it is evident that the connections to the upper and lower portions
46 and 48 are all of the quick disconnect variety so that the m~,hin~,ry ~ tP~ with any
particular station 22 may be readily removed from the remainder of the m~.hin~o.20. Moreover,
3 o the connf~ction,~ for power and fluid may likewise be of the quick disconnect variety. Thus, the
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-- 11 --
c~onll~.;!;on~ such as those shown at 120 may be disconnected by simply pulling them apart or
unscrewing them and then the mPch~ni~m~ 146 holding the upper and lower chambers 47 and
49 may be ~li~nl~ in the same fashion so that the upper and lower ch~l..h~, 47 and 49
may be quickly removed.
The un1n~1in~ station 22d, shown in Figure 11, inrl~ s an lmlo~tiing conveyor 126
and a tray pusher 128. At the app~o~liate time, the trays 55 in a platform 24 are pushed
upwardly by the cylinder 130 of the pusher 128. Then the trays are pushed laterally by the
slider 132 ~we~d by cylinder 134. The trays are pushed onto the conveyor 126 as in~1ir~t~rl in
10 Figure 13.
The m~t~.hinto iS o~l~led generally as follows. Initially, a plurality of trays 55 are
f~ on the conveyor S0 of the tray load assembly 42. As in~1ir~t~cl in Figures 3 and 4,
the trays are formed into two rows of four trays through the operation of the stop bars S4 and
15 58. Trays are ori~in~lly allowed to ride up against stop bar S8 so that they slide relative to the
rotating conveyor S0. A second row of trays then back up to the first row of trays.
-
As shown in Figures 5 and 6, at the a~ iate time, the second stop bar 58 is lowered
allowing the first row of trays to pass on to the bed 64. Each bed 64 is Lh~ ~earl~l lowered so
2 0 that each tray SS is held in a slot 26 in the platform 24.
After a passage of time, the platform 24 is rotated 90 degrees to the station 22b.
Thel~arL~" the stop bar S8 is operated to allow the second row of trays SS to be loaded into a
subsequent plalrullll 24 rotated into station 22a from station 22d. From station 22b, the
~lalro,m 24 rotates into the station 22c as shown in Figure 1.
As shown in Figures 7 and 8, at the tooling assembly 44, the platform 24 is lifted from
its ,.~ , 72 and held between the upper chamber 47 and lower chamber 49 of assembly 44.
Precise ~lignment is achieved through the operation of the pins 78 which engage mating holes
3 0 82 in the platform 24. The tapered portions on the pins 78 and holes 82 interact to guide the
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p~ r~"~" into the desired portion within the station. In this way, the trays 55 are precisely
po~itinnPd with respect to the tooling assembly.
After the p]~ ll 24 is in position, a vacuum is drawn in the upper çh~mhP.r 47 through
5 the gas ~Ych~n e passage 132. This is possible since the upper cl.~...l.~. 47 sealingly ~ngavP$
the film 92 through o-ring seals 84. After the drawing of a vacuum is begun in upper ~ ."l~
47, a vacuum is begun to be drawn in the lower .',h~."ll~.. 49 via a vacuum tube 139. This is
pu~ lc because the lower cl~".l~el 49 sealingly Png~gP~ the plaL[o~lll 24, against the upper
~h~ml~er 47, through an o-ring seal 84.
As a result, good fluid col.~.n~ tic-n is achieved with the exterior of the tray 55, under
the film 92. This is because the vacuum in the upper chamber 47 lifts the film 92, allowing air
to be ~ ed from the tray 55 through a series of holes on slots 150 in the bottom of recess
112 of the platform and out the opening 130. The provision of the filler 134 makes this process
15 pl~)ceed more quickly.
After the vacuum is drawn, a desired atmosphere is then pumped into the tray via the
openings 151 and 136 from the gas tube 137. This atmosphere is preferably one which is
ced in oxygen content to extend the life of the packaged food product.
As shown in Figure 10, the film 92 may be heat sealed to the tray 55 using the sealer
86. This operation may be a conventional heat sealing operation. The sealer 86 reciprocates
dc,w,lwanlly under the control of the stops 102 in response to ~h~nging fluid pressure in the
cl~allll)~r 103.
After the film 92 is sealed to the tray 55, the film is cut by cutter 88. The cutter 88
reciprocates downwardly to cut the film 92, eventually entering the recess 112. The movement
of the cutter 88 is controlled by the fluid pressure in the chamber 117. In this way the desired
~tmo~hPre may be sealed into the package. Of course, other gas exchange techniques may be
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- 13
utilized as well. Advantageously, the atmosphere inside the assembly 44 is reduced in oxygen
content so that the food product will have a longer useful life.
-
The opP~tinn of the cutter 88 may be adversely ~ rr~;led by the ~mhient heat within the5 :~mhly 44 which is greatly ;lllp.~ ~ by the heat created by the heat sealing ope~ti~
n This
heat may distort the cutting blades and cause in~C~ ies therein. For this reason, a source of
cooling fluid, for ~ ~ ~ '~ water, may be circulated through the passage 118 so as to cool the
cutter 88.
After this opPr~tion is csmpl~~e, the upper chamber 47 and lower portion 49 may be
moved apart and the rolls 96 and 94 advanced so as to bring a new section of film into position
bc;Lw~n the ~ "he~ 47 and 49. Trays 55 are then advanced to the next station 26d.
As shown in Figure 11, in station 22d the trays 55 are po~ition~d over the tray pushers
128 and cylinders 130. At the a~ iate time, one or more trays 55 are pushed upwardly
through the action of the cylinders 130 and pushers 128 as shown in Figure 12. Thereafter, the
trays may be pushed laterally by the slider 132 and its cylinder 134 as shown in Figure 13.
Then the trays may be taken away from the rotary conveyor by the llnln~-ling conveyor 126.
The entire operation is f~rilit~t~cl by the rotary arrangement of the stations 22. The
operation of the conveyor is continuous since it is laid out in the rotary arrangement. In this
way, problems arising from the need to return the platforms 24 to the initial position at the end
of a linear conveyor are elimin~t~l
2 5 Moreover, with the rotary arrangement the central area may be occupied by the
conveniently located surge tank 38. This tank supplies a source of fluid pressure for the various
operations in the surrounding rotary conveying apparatus. The tank 38 is normally closed by
caps 154 on both ends. As shown in Figure 14, a drain 152 is provided at the bottom of the
surge tank 38 for r.ol~ing a ~nili~ g solution. The drain may be closed by a removable cover
156. The interior of the tank 38 may be washed with the bacteriostatic solution to .. i.~ i,P
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b~rtPri~ transfer to the pAr~gin~ The tank 38 also provides the support for the drive
mf~h~ , . . 32 and rotatable ring 30.
lrlitinn, because of the rotary arr~nf~PmPnt of the conveyor, any particular station
5 may be easily ~r~e-c~l for removal from the rest of the m~rhine Any particular station may be
easily rep~ d with a more a~lo~ ; station for any particular operAtion Also, a
m~lfimrti-~nin~ ~"dlu~ may be replaced with a working a~ dlllS. Re~ll~ of the rotary
~",.~l~e-~ t, access to the individual stations for repair is fAcilit~t~d
Repair and rerl~cP-mPnt is also fAcilitAted by making the various connP~ti~n~ to the
stations for Pl~cJrir~l and fluid power of the quick disconnect variety. Moreover, by making the
means of ~tt~rhmPnt of the particular apparatus to each station of a quick discu-~lecl variety it is
pcs~il,le to change stations quickly to convert the mArhine for other uses or to replace a broken
piece of equipment.
An ~lt~rn~tP cutting system 288 includes a blade 290, as shown in Figure 15.
Particularly, a cutting blade 290 is mounted on a support assembly 292 which in turn is
:,u~l~o-L~d on a reciprocating bed 294. The movement of the bed 294 is controlled by cylinders
296 and 298. Also mounted on the bed 294 are a set of opposed film holders 300 which may
2 0 have a vertical length somewhat longer than the vertical length provided to the blade 290.
As shown in Fig. 18, the blade 290 may have a closed configuration such that it is
capable of plln~hing out a portion of film from the web 92. The blade 290 is ideally made of
low mass such that the heat ~ cir~ti~n of the blade is minimized. The support assembly 292
provides for slight relative movement between the bed 294 and the blade 290. In this way,
expansion arising from heating of the blade 290 may be allowed. Also, the support assembly
292 may thermally insulate the blade 290.
A heater 302 extends along the periphery of the blade 290 as close as possible to the
cutting edge 304 of the blade 290. By minimizing the mass of the blade 290 and ~itn~tin~ the
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heater 302 close to the cutting edge 304, the heat ~iiCcir~tion can be reduced. This permits the
use of relatively high t~ s at the cutting edge 304. In the ill-lct~tPd elllbodilllen~ the
- heater 302 is received in a slot 303 in the blade 290, as shown in Figure 16.
The heater 302 may be a cable heater that incl~ s a pair of high ~ lC~ C~
heating wires s~ l~l from an outer metal sleeve by an pl~tric~l inc~ tnr. Ideally, the heater
302 is on the order of 1/16" thick so that it can be placed very close to the cutting edge 304.
Moreover, the blade 290 may be made relatively small, for eY~mple, on the order of 1/2" high
and 1/4" wide.
It is dP-sir~hle that the cutting edge 304 be of a small width. In one embo lim.-nt the
cutting edge 304 has a width of less than 20 mils and, ideally it has a width of about lS mils.
The heater 302 is supplied with electrical current from a current source not shown.
~L.r~l~ly, the current source and the heater 302 are configured to allow heating of the cutting
edge 304 to extremely high le~--~l~lul~s, for example, greater than 500~ F. Preferably, the
heater heats the film to be cut to the point where it quickly vaporizes. In a plc~rc~ d forrn of
the present invention, heater tPm~.,.l...~s on the order of about 600~ to 900~ F are achieved.
The precise t~ pel~L~lre used dep~n-lc on the vaporization point and thit~knecc of the particular
2 o m~tPri~l being cut.
The cylinders 296 and 298 may be air cylinders which quick~y move the bed 294
downwardly and upwardly. Ideally, the down cycle of the bed 294 may be on the order of
tiorlc of a second. Cutting may be advantageously achieved through the appli~tion of heat
2 5 rather than with ~Jl'~i~iUlt~.
The film 92 to be cut may be held by holders 300 which include clamps 340 connected
to the bed 294 by spring biased bolts 342, as shown in Figure 16. The bolts 342 may be
mounted on an o-ring 344. The ends of the holders 300 have bumpers 346. Coil springs 343
3 0 encircle the bolt 342, and are retained at the lower end by the clamps 340.
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12.~rr. 1;1~g to Figure 20, the ~n~ngPmPnt of the holders 300 is ill~lctr~tPd, with the web
92 direction in-lir~t~ by the arrows l~hPllP~I "W." The trays SS are s~P~I~ rll by a width
slightly greater than the width of the clamps 340. Thus, the film 92 is ret~inf~ r~
l~ww.~ the trays 55 by the clamps 340. The prriphP.r~l portions of the film 92 are held by the
~"~l~;"g action of the upper ~ ."b.~.r 47 and tray plate 24. This is particularly advantageous in
that the amount of film which is devoted to film holding is ",;.)i.,.i,PA This means that less
film is wasted.
Referring to Figure 16, the cutting blade 290 is connPrtPA to the movable bed 294. The
.mhly 292 may indude a set of spring biased pins 308 that may be used to mount a carrier
310 for up and down movement. Two opposed sets of stanchions 313 and a movable strap 312
are sllq~-ntlp~d by pins 314.
As shown in Figure 17, the st~nrhicm~ 313 also connect the fixed strap 316 to the blade
290. The strap 316 fixedly c~ P~!~; to the blade 290 at 318. Relative movement between the
blade 290 and the strap 316 may be provided by the slot 319. In this way, the blade 290 can
expand in length relative to the strap 316. The fixed strap 316 may connect to the bed 294 by
spring biased pins 308, the carrier 310, and the pins 314.
The movable straps 312 include oversized holes 322, as shown in Figure 19. The pins
314 have reduced ~ mpter ends 315 which are held in the holes 322 by retaining rings 323.
The st~nr,hions 313 pass through the straps 312 and connect the straps 312 to the blade 290.
The sf~nrhion~ 313 have a ceramic bushing 324 and washer 326 between themselves and the
straps 312 to provide incul~tiQn against heat transfer from the blade 290 to the rest of the
m~rhine. The same system is used to provide heat insulation on the fixed strap 316.
The connections to the blade 290 are shown in Figure 18. The fixed strap 316 allows
the blade 290 to expand along its length only, because of the slot 319, which allows blade
e~cp~n.~inn relative to the fixed connection at 318. The pins 314 connect the strap 316 to the
-
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ca~Tier 310 between the slot 319 and point 318. The other three sides of the blade 290 are
su~ d by moveable straps 312. Each strap 312 connects to the carrier 310 by pins 314.
- Each pin 314 is received in an oversized hole 322 which allows movement of the strap 312 in
all directions relative to the blade 290. The moveable straps 312 then are connected to the
5 blades by ~uLwanlly located ct~n~hinnc 313.
Through the operation of the system 292, the blade 290 can accommo l~tP ~cc~Pnti~lly
any heat ~ m~o.~ related stresses. Moreover, because of the inc~ tion capabilities of the
system 292, the blade heat fiiCcir~tion is reduced.
The present invention can be used to cut a variety of plastic films. This incll-dPs films
that are elastic and inel~cti- That is, the same machine may be capable of cutting both types of
films. Where elastic films are l-tili7Pd, it is desirable in many cases to cause the elastic film to
be tPncion~i. In this way, when the film is cut, it tends to pull back after it is cut. This aids the
15 cutting process while prod~ ng a better looking edge. Moreover, the use of heat chrinkin~ film
may improve both the cutting action and aL,~ ce of the finiche~ product.
The present invention advantageously involves the use of lwn~ldLllres which are
s--ffi~ ntly high to cause plastic vaporization. This accomplishes both rapid and reproducible
2 0 cutting without blade fouling. For example, a coextrusion of polyethylene and ethylene vinyl
acetate may be severed with the present system. At approximately 250~ F this material softens
s--ffici~-ntly to be sealed to other layers. At about 350~ F, melting begins. At about 600~ F,
some v~ on occurs, but cutting may not be clean all around. Plastic strings may be
created. However, at about 800~ F for example, there is effective v~oliz~lion of the film.
25 The film may be cut deanly and reproducibly. The use of force is ~-nn~-~çcc~ry to the cutting
and no b~-lfing plate is nPcecc~ry on the side of the film opposite the blade.
The system 288 may be operated in the following fashion. Upon activation of the bed
294, the blade 290 moves quickly downwardly and through the film 92. The severing action is
3 0 the result of film ~ ion
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Prior to cutting, the film is held at two spaced l~tion.c. On one side, it may be held by
the sealer 86. On the other side, it may be held by the holders 300 which initially extend past
the blade 290, and the upper . l .~ . 47.
13. lw~~l the point where the film is held by holders 300, the sealer 86, and the upper
rh~ 47, the film may be un~u~,~;l. It is at this unsupported intPrmPAi~te position that
the film, most adv~nt~Poucly, is cut. The film 92 may be sealed to the tray 55 on contact by
the sealer 86.
The improved film cutting system 288 may be used in place of the system 88. It is also
possible to seal the film in one station and to cut the film at a subsequent station under ~lirr~
~tmn~hPric con~litionc. For eY~mphP-, the film may be sealed under vacuum con~iitinnc at one
station and severed at a sul,sequenl station under atmospheric conditions.
A stair-stepped tray unloading slider 432, shown in Figure 21, in~ rles a stair-stepped
series of pushers 434. When the cylinder 134 reciprocates, each of the trays 55 are pushed a
dirr~ n~ t~nce onto the conveyor 126.
~t The trays 55 may then be off-loaded to a second conveyor (not shown) which
advantageously may be a belt conveyor operated at a higher speed than the conveyor 126. In
this way, the initial orr~~ g provided by the slider 432 can be amplified sufficiently that each
of the ~ays are offset at least one tray length from one another. Using an a~ )liate guide (not
shown), the suitably offset trays may be easily guided into a single file line of trays.
A tray loader me~h~ni~m 542, shown in Figure 22, includes a system to enable different
sizes of trays to be accomm~l~tPli by essentially the same p~ck~ging m~hin~ While the
pldlrc.,l" 24 illnstr~t~d in Figure 22 may accommo l~te four trays S5 at one time, it may be
desirable to operate the machines with a dirr~nt number of trays per platform. For example,
3 o with wider trays, it may be desirable to operate with three trays per platform.
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The station 22a may advantageously be designed to operate only when all available
rn....24 o~~ gs 26 are filled. This may be accomrli~hrd using a series of pivotal flags
544 and an ~ILal~d light llel~ p device 548. The flags 544 pivot about the pin 546 from the
5 "up" position shown in Figure 22a to the "down" position shown in Figure 22c. A light beam
"B" ~xluced by an infrared light source 547 is blocked when any of the series of flags 544 are
in the "up" po~iliun, as ill~ d in Figure 22a. So long as one flag 544 is in the "up"
po~itinn, the station 22a may be ~li~hl~
Advantageously, a series of flags 544 are positioned across the width of the conveyor
50. Each flag 544 protrudes upwardly in the "up" position above the upper surface of the
conveyor 50. The conveyor 50 may be formed of a plurality of thin belt strips 550 which are
str~ by the flags 544, for .ox~mrl~
In this way, when a tray 55 passes over a flag 544, the flag 544 is pivoted to the down
po~itinn. If the flags 544 are suitably spaced across the width of the conveyor, any possible tray
width will be sensed. Thus, at one time, the m~rhinP can be run with four trays per platform
and at other times, it may be run, for example, with three trays per platform. Re~llse the flag
system detects the absence of a full contingent of trays, and because n.-i-ec~. y flags, such as
2o the flags 544a in Figure ~c, may be set in the "down" position, tl~e machine quickly
accollllllodates dirr~l~nl tray sequences. Flags may be latched down using a suitable catch (not
shown).
When the ~lugl,.l~ l~ tray sequence is present as sensed by a full contingrnt of "down"
flags, the light beam "B" is ~let~t~ by a suitable detector 548. The stop bar 58 may be
lowered to allow tray loading. On the other hand, so long as even one flag 544 is "up," tray
loading will be prevented. Since the lower ends of the pivoted flags are heavier than the upper
ends, the flags 544 return to the "up" position after the trays move over the flags.
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A tray loader 550 which in~ des the capability to separate trays that have become
inadvertently con.~P~ d to one another is shown in Figures 23 through 26. As shown in Figure
23, a pair of trays 55a and 55b may have their flanges overlapped so that the trays become
stuck to one another and travel along the conveyor 50 together. This may be lm~iecir~hl~.
5 be~ ce when the trailing tray is stopped, the leading tray may not proceed onto the tray
platru~ 24 at the desired time.
As shown in Figure 24, tray loader SS0 includes a modified stop bar 554 ~w~d by a
pair of cylinders 556 and 558. The cylinder 558 connects to the element 560 to allow upward
and downward reciprocation of its free end 562. Astride the P,lPmpnt 560 is an elPmPnt 564
having a free end S66. The elemPnt 564 connects to the cylinder 556 in such a fashion that it
may pivot towards and away from the element 560 in the direction of movement of the
conveyor 50. As shown in Figure 23, a pair of elements 560 and 564 may be used with each
tray, if desired.
Referring to Figures 25 and 26, the trays 55~ and 55b may be s~,~l~i from one
another by op~ldling the cylinder 556 to pull the element 564 in one direction causing pivoting
movement of its free end 566 forwardly. As shown in Figure 26, the elP-mpnt 564 may be
angled to ~llgmPnt the forward movement provided to the lead tray 55b. If the sel)~dl(~r
20 mPrh~nicm is u~c;ldLillg in every in.ct~nce, any time trays which are overlapped exist, they will
be aulon~alically se~dled. Moreover, the acceleration provided to the lead tray helps it to stay
in contact with the conveyor 50. After one cycle, the cylinder 556 may be operated to return
the Pl~omP.nt 564 to the position shown in Figures 23 and 24.
2 5 While the present invention has been described with respect to one pl~r~;lled
embodiment, those skilled in the art will appreciate numerous modifications and variations
thtlerlul.l. The appended claims are intended to cover all such mo-lific~ti-)ns and variations
which occur to one of ordinary skill in the art.
