Automatic packaging

Heat sealing of foam-paper laminates and the like around articles to cushion them. Foam can be coated with anti-stat and/or corrosion inhibitor to protect articles against static electricity and/or corrosion. Such coatings can reduce the heat sealing temperature. Laminate portions to be heat sealed can be pre-heated to shorten heat sealing dwell.

The present invention relates to automatic packaging of articles that are 
to be shipped or otherwise transported. 
Among the objects of this invention is the improved automatic packaging of 
articles that are to be protected against mechanical shock as well as 
against static electricity or corrosion.

The practice of packaging articles by sandwiching them between 
cemented-together supported foam sheets such as paper-foam laminates, 
leaves something to be desired for some types of articles. Thus where the 
articles are printed circuit boards or the like that are sensitive to 
static electric charges, the packaging material should be treated with 
anti-static agents. Unfortunately anti-static agents tend to lose their 
effectiveness when combined with or covered by the cohesive-nonadhesive 
coatings that are particularly desirable for use to cement together the 
packaging sheets without heating. 
A similar difficulty exists with respect to articles that should be 
protected against corrosion while packaged. Corrosion inhibitors such as 
the well-known volatile corrosion inhibitors, some of which are referred 
to in U.S. Pat. Nos. 4,321,297, 4,308,168, 4,251,462, 4,374,174, 
3,080,211, and 2,829,030, tend to deleteriously affect 
cohesive-nonadhesive coatings. 
Cohesive-nonadhesive coatings have been very desirable because they are 
inexpensively applied to supported foam during the manufacture of such 
foam laminates, and they are very effectively used to cold cement such 
foam layers to each other, but are otherwise not adhesive so that they do 
not have to be protected by coverings to keep them from sticking to other 
objects after they are manufactured and before they are cemented together. 
According to the present invention the cohesive-nonadhesive coatings are 
eliminated and the anti-static and corrosion-inhibiting coatings used to 
lower the melting range of the foams so that they are easily heat-sealed 
together. Although heat sealing generally takes more time than the cold 
pressure sealing that has been used with the cohesive-nonadhesive 
coatings, the automatic heat-sealing of a sequence of articles into 
successive packages pursuant to the present invention is effected at a 
rate very close to if not faster than the prior art cold sealing. 
Turning now to the drawings, FIGS. 1, 2 and 3 show a succession of 
relatively flat boards 11, 12, 13 being packaged between two paper-foam 
packaging laminates 21, 22. These laminates can be of the types described 
in U.S. Pat. No. 4,321,297, carrying an anti-static or 
corrosion-inhibiting layer or a layer that contains both an anti-stat and 
a corrosion inhibitor, on the face of the foam. The foam layer itself is 
preferably one that heat seals at about 100.degree. C. and is no thicker 
than about 3/16 inch. The antistat and/or corrosion inhibitor lowers the 
heat sealing temperature to about 95.degree. C. The backing for the foam 
is preferably not over about 1/16 inch thick with a tensile strength at 
least 20 times that of the foam layer. 
Each laminate 21, 22 is provided as a long sheet rolled up and held on a 
dispensing reel, not illustrated. Sheet 21 is fed foam side up onto a 
spaced pair of adjustable supporting angles 26 adjusted so that the floors 
28 of the angles are essentially in a horizontal plane, with flanges 30 
extending upwardly and closely fitted about the sheet's side edges 34. 
Sheet 21 is pulled longitudinally along the guiding angles by two pair of 
gripping discs 41, 42 and 51, 52. Discs 51, 52 are fitted to an adjustable 
shaft 54 that is rotatably held in two brackets 56 mounted under the 
supporting angles 26. Discs 41, 42 are similarly fitted to an adjustable 
shaft 44 above the guides, rotatably held by an arm 46 that is resiliently 
pressed downwardly as by spring 47 to cause the upper discs 41, 42 to 
pinch against the lower discs through slots 48 cut in the angle floors 28. 
Either or both pairs of discs are rotated in the direction of arrows 58 as 
by sprockets 59 mounted on the disc shafts and driven by worms connected 
by flexible shafts 57 to the opposite ends of the armature of a drive 
motor 55, so that the outer face of each disc is exposed. The discs pinch 
the packaging sheet 21 between them and in this way pull that sheet in the 
direction of arrow 62 along the supporting angles. Notches 64 are cut out 
of the upwardly extending flanges 30 to keep them from covering the outer 
faces of discs 41, 42. 
The articles 11, 12 and 13 are placed on designated spaced locations on the 
foam face of sheet 21 as it is pulled along. At the same time the second 
packaging sheet 22 is pulled from its dispensing reel to engage the edges 
of discs 41, 42 and to be thus pulled down into firm foam-to-foam 
engagement with the lower sheet downstream of where the articles to be 
packaged are placed on the lower sheet. 
The outer faces of all the discs are heated by reflector-equipped heat 
lamps 70 placed so that they focus infra-red radiation on those faces as 
well as on the adjacent edge portions of the packaging sheets. Additional 
heat lamps 71 can be aimed directly at the sides of the sheet faces at 
locations just upstream of the disc edges to further preheat all or some 
of those sheet edges immediately before they are pinched together by the 
discs. This preheating supplements the preheating of the upper sheet as it 
is pulled around the hot edges of upper discs 41 from the disc tops to the 
disc bottoms. For best results the preheating of lamps 71 is confined 
essentially to the narrow sheet locations at which the pinching and 
sealing take place. 
The frame has an upper cross piece 81 held by springs 83 that extend to an 
overhead mounting site, to thus hold the frame in its upright position, as 
illustrated. The side members 85 of the frame have their upper portions in 
the shape of channels 87 that open towards each other to provide tracks 
within which is slidably fitted a guillotine cutter 89 that extends 
transversely of the packaging sheets and is as long as the widest 
packaging sheets to be processed. Cutter 89 is connected for vertical 
reciprocation by a pair of air cylinders 91 actuated by flexible air hoses 
that are not illustrated. An anvil 93 is fixed between the frame side 
members 85, and has a slot 95 to receive the guillotine blade as well as 
embedded electric resistance heaters that heat the anvil to heat-sealing 
temperature. Similar heaters can be incorporated in the guillotine cutter 
89 on either side 88 of its cutting blade. The lower faces at 88 are 
horizontally flat so that when the cutter is propelled downwardly the 
faces at 88 forcefully engage the packaging sheets and press them against 
heated anvil 93. This act of propulsion also transversely cuts the 
packaging sheets and is timed so that it occurs when a portion of the 
packaging sheets about halfway between successive packaging articles, is 
over the anvil. 
The forceful pressing of the cutter against the anvil is maintained for the 
length of time needed for the heat from the anvil and from heaters at 88 
to effect a transverse heat-sealing across the packaging sheets. This may 
take as long as a second or so, and during that time the packaging sheets 
continue to be advanced by the pinching discs to push the cutter-and-anvil 
assembly in the advancing direction, to pivot the cutter frame 77 around 
its pivot 79. When the transverse heat-sealing is completed the air 
cylinders 91 cause the guillotine cutter 89 to be retracted away from the 
anvil, thus releasing its grip on the packaging sheets. The packaging 
sheet section downstream of the cutter is accordingly released and slides 
down the curved guideplate 99 as a completed package indicated at 101. 
Adjustable side guides 103 may be provided to help direct the completed 
package. 
Upon the retraction of the cutter 89, the packaging sheets upstream of the 
cutter are no longer gripped between cutter and anvil, so that springs 83 
pivot the frame 77 back to the vertical position against stop 90. The 
cutter frame is now ready to make the next transverse cut and heat-seal. 
Arcuate fingers 96 extend from the anvil and follow it in its downstream 
movement to help suport the downstream end of the packaging sheet assembly 
while the anvil is later returned by springs 83. One cycle of such 
heat-sealing transversely seals the packaging sheets on both sides of the 
cutter blade, so that it closes the downstream end of the package being 
cut loose as well as the upstream end of the next package. 
The cutter 89 preferably has its cutting edge inclined guillotine-style at 
about a 5.degree. to 20.degree. angle with respect to the anvil which can 
be horizontal. This inclination gives the cutting a scissors-like action 
that reduces the cutting force. 
FIG. 5 illustrates a modified cutting and heat-sealing structure that 
should require less cleaning. Here the anvil 193 has a blade-receiving 
groove 194 cut into its upper face at an angle of 5.degree. from the 
vertical which is indicated by dash line 196. The angle is exaggerated 
somewhat for greater clarity. This provides the anvil with a cutting edge 
197 that has a little overhang with respect to the adjacent groove face 
198. A similar tilt is provided at the face 188 of a cutter bar 189 that 
has a cutting edge 187 that co-acts with anVil edge 197 to do the cutting. 
Cutting edge 187 has a guillotine-type inclination as shown at 186 as well 
as an upward rake 185. 
Blade 189 is held in an appropriate groove in cutter bar 184, as by a 
series of set screws 183, without interfering with the heating provided by 
electric heating wires fitted in grooves 170. Similar heating grooves 171 
are in anvil 193. The heating-groove-containing faces of the cutter bar 
and the anvil can be cut n removable face plates of both, for ease of 
assembly. 
Because of the overhang of the cutting edges 197 and 187, debris resulting 
from the cutting action does not tend to build up to the point that it 
interferes with the cutting. The overhang can be as little as about 3 
degrees and as much as about 10.degree. if desired, and can be confined to 
only one of the cutting edges. 
To help the incoming packaging sheets push the transverse sealing assembly 
75, the cutter actuation can be connected to independently start rotating 
that assembly, as by having the side face of cutter 89 engage a cam 92 as 
the cutter reaches heat-sealing engagement. 
The guide angles 26 and pinch discs are all arranged to be adjusted for 
packaging sheets of different width. The transverse cutter extends to the 
maximum width of the guide angles and needs no width adjustment. 
It is also helpful to apply some pre-heat to the transverse sealing site. 
Thus a long thin heat lamp 106 can be mounted in a reflector 108 that 
directs the lamp output as a narrow band approximately 1/2 inch wide and 
as long as the entire width of the transverse sealing assembly. The 
lamp-carrying reflector 108 is pivotally mounted as at 110 so that it can 
pivot and in this way longitudinally scan along the longitudinally sealed 
packaging sheet assembly immediately upstream of the transverse sealing 
site. 
This scanning is shown as controlled by a control arm 112 projecting 
downwardly from the reflector and having a sensing tip 114 hanging in the 
path of the bumps formed where the packaged articles are sandwiched. As 
such a bump reaches the freely hanging tip during the progress of the 
packaging, it engages and pushes the tip in the downstream direction thus 
tilting reflector 108 to cause the pre-heat it directs, to scan downstream 
in synchronism with the sandwiched articles. 
Sensing tip 114 is shaped and pivoted with relation to the shapes of the 
bumps, to cause the reflector tilting to remain accurately focussed at the 
same location on the top surface of the upper packaging sheet 22, moving 
with that sheet so as to effectively pre-heat that location just before 
the transverse heat-sealing takes place at that location. To this end the 
sloping nose of a bump coacts with the tip 114 to gradually slow the rate 
of reflector tilt a little, after the tilting starts to thus compensate 
for the extra advancing effect that the tilting has on the heat 
projection. The transverse heat-sealing is shown as controlled by a limit 
switch 120 in the tilt path of control arm 112. 
Tip 114 is made springy and short enough to be tilted completely out of the 
way as, or shortly after, switch 120 is actuated, so that the bump causing 
the tilting passes by. When that passage is completed the tip is pulled 
back to the illustrated position by return spring 122, and is now ready 
for the next bump. 
Instead of, or in addition to, the preheating of the upper surface of the 
upper sheet 22, similar pre-heating can be applied to the lower surface of 
packaging sheet 21 in corresponding locations. The same control can be 
used to direct both such transverse pre-heatings. Infra-red radiation can 
also be used to pre-heat the foam face of packaging sheet 22 along the 
heat-sealing region, as that sheet travels around disc 41. Pre-heating can 
also be applied to the lower face of packaging sheet 21. 
The heat lamps 70 can be replaced by electric resistance heaters fitted to 
the outer faces of the discs and electrically insulated from those faces. 
Such heaters have circular contacts that are carried by the discs and are 
engaged by fixed brushes connected to a supply of electric current. 
The output of the packaging machine can be increased by widening it so that 
it operates on packaging sheets twice as wide and then fitting each 
pinching disc shaft with an additional pinching disc midway between the 
two illustrated in FIG. 2. The two additional pinching discs can moreover 
be provided with a cutting edge and mating groove so that they slit the 
wide packaging sheet longitudinally along its center line, and also heat 
seal on both sides of the slit. Articles can then be simultaneously 
packaged on each lateral half of the packaging sheet combination. 
FIG. 4 illustrates another technique for increasing the packaging speed. 
Here an apparatus like that of FIGS. 1-3 has a transverse sealing frame 
175 that carries two transverse cutter-and-anvil assemblies 180, 280 
spaced apart an adjustable distance by linkage 179. Both of these 
assemblies can be operated at the same time so that two time-consuming 
transverse cut-and-seal operations are completed at one stroke. A 
packaging sheet combination can accordingly b moved through the apparatus 
of FIG. 4 about twice as fast as through the apparatus of FIG. 1. The 
transverse pre-heating of FIG. 1 can also have a second such preheater 
immediately upstream of the downstream cutter, operated by the same 
control that operates the upstream transverse preheater. Interdigitated 
fingers 181, 281 extending toward each other from the respective anvils 
move under the sandwiched sheet assembly to help guide the anvils under 
that assembly in their upstream return stroke. 
For the present invention it is desirable to use polyethylene foams, and 
particularly foams of low-melting polyethylene which can be heat-sealed at 
95.degree. C. or even somewhat lower. Foams made of well-plasticized 
resins are also desirable because they also have low melting points. The 
anti-stat and volatile corrosion inhibitors are preferably plasticizing 
agents for the resins they are coated on, to lower their melting points. 
However polypropylene, polystyrene and other heat-sealable foams can also 
be used. 
Where high output is not needed, the machine can be operated stepwise so 
that the packaging sheets are given a succession of stepwise advances with 
the sheets stationary between steps. The stationary dwells are made 
sufficiently long in time to permit the guillotine cutter to cut and 
heat-seal transversely. At the same time the longitudinal heat-sealing 
discs should not be so hot as to char the sheets during the dwell for the 
transverse heat-sealing. The transverse heat-seal frame 75 need then not 
be pivotally mounted. 
The supported foam laminates used in the present invention can have 
supporting laminations that need not be paper. While paper is a very 
desirable supporting member by reason of its low cost as well as its 
strength and resistance to damage by the heat needed for heat-sealing, the 
paper can be replaced by sheets of felted fibers other than cellulose or 
by plastic films or even metal foil. Foils of metal such as aluminum 
preferably have thicknesses of up to about 10 mils, inasmuch as greater 
thicknesses unduly add to the expense as well as to stiffness of the 
supported foam. 
Metal supporting layers sandwiched about an electrically-sensitive object 
can be electrically connected together by the cutting action that 
separates individual packages, or by stapling or the like, to form an 
electrical shield around the object packaged. Metal supporting layers are 
also very highly conductive to heat so that heat-sealing times can with 
metal-foam laminates be reduced to less than 1/2 second. 
Polyethylene terephthalate films or felted fiber sheets that withstand 
temperatures of about 160.degree. C. that may be applied to effect 
heat-sealing, are also suitable, and can be used in film or sheet 
thicknesses as small as 1/2 or 1 mil. Such small thicknesses are still 
quite strong and also reduce the time required for the heat-sealing heat 
to penetrate through to the foam. 
Supporting layers of woven or unwoven strips of plastic film about 1 to 3 
millimeters wide can also be laminated to the heat-sealable foam to make 
packaging sheets. 
A foam support an be made of combinations of layers. Thus a paper layer can 
be reinforced with glass or other fibers or laminated with metal foil or 
plastic film. 
Obviously many modifications and variations of the present invention are 
possible in light of the above teachings. It is therefore to be understood 
that within the scope of the appended claims the invention may be 
practiced otherwise than as specifically described.