Machine for compression band packaging

Packs of product move along a defined path, compressed in the grip of carrier jaws. A pair of webs of thermoplastic sheet material move towards said path from opposite sides thereof and are joined at a heat-fused seam to form an effective continuous strip across said path and into which a pair of carrier jaws moves with its pack. Pressure jaws converge just behind the carrier jaws to form the strip into a loop around the carrier jaws and produce two parallel, slightly spaced heat-fused seams between which the webs are severed and one of which connects the ends of said loop to form a band around the carrier jaws while the other connects the webs into a strip for formation of the next band. Until the band-completing seam has cooled, the carrier jaws keep the pack compressed enough to prevent seam rupturing tension on the band, then diverge enough to tension the band slightly, whereupon band and pack, in unison, are slid endwise out of engagement with the carrier jaws. The two parallel fused seams and the cut between them are produced simultaneously by a single strip-like electrically heated element.

FIELD OF THE INVENTION 
This invention relates to machinery for the packaging of resiliently 
compressible products such as stacked paper towels and stacked paper 
napkins; and the invention is more particularly concerned with apparatus 
for forming compact packages, each comprising a quantity of a resiliently 
compressible product surrounded by a confining band of thermoplastic 
material by which the product is kept compressed until the band is broken. 
BACKGROUND OF THE INVENTION 
Commercial and industrial purchasers of paper towels and paper napkins wish 
to receive such products in packages that are as compact as possible. In 
many cases each such package is intended to provide a fill for a 
dispenser, and the package should contain the largest number of units that 
can be fitted into the dispenser. Since such a product occupies much less 
space when compressed than when unconfined, the product should be under 
substantial compression in the package. 
Some prior compression packages have comprised cardboard tubes of 
rectangular cross-section, into which precompressed packs of product were 
inserted. Although these were relatively satisfactory, the cardboard tubes 
were also relatively expensive. 
Paper bands have also been used to confine stacks of paper towels or the 
like under compression. Although low in cost, paper bands could sustain 
only limited tension and therefore did not lend themselves well to the 
making of an adequately compact package. Furthermore, packages comprising 
paper bands had a tendency to be somewhat out of straightness, or to have 
a rumpled edge, or in some other way to be deficient in clean-cut 
neatness. 
Light-weight thermoplastic sheet material, which is tough, inexpensive and 
somewhat elastic, is very suitable to be formed into bands or sleeves for 
compression packages, but its employment for the purpose poses numerous 
problems. Some of these problems arise from the nature of that material, 
which is very supple and tends to be charged with static electricity that 
makes it sticky. Hence control of the material requires that every edge 
portion of it shall at all times be either supported or maintained under 
tension, substantially all along its length. Other problems are posed by 
the need for bonding such material by forming heat fused seams that have 
little strength until they are cooled substantially to ambient 
temperature. 
To avoid these problems, one procedure heretofore used for obtaining a 
compact banded package with thermoplastic sheet material was to form the 
material into a band around a relatively uncompressed pack of product, and 
then heat-shrink the band to compress the product. Expensive energy had to 
be expended for the heat shrinking step, and in the resultant package the 
product was not necessarily compressed to the fullest or most desirable 
extent. 
In some machines heretofore employed for compacted band packaging of 
compressible product, each band was formed from a web of thermoplastic 
sheet material that was drawn off of a braked supply roll under lengthwise 
tension, and the tension thus imparted to the band was relied upon to 
compress the product. Machines which operated on this principle tended to 
be slow because of the braking of the supply roll. Furthermore, the amount 
of compressive compaction that could be imparted to the product, which 
depended upon the tensioned stretching of the band material, tended to be 
limited. 
The present invention contemplates a packaging machine whereby individual 
wrapper bands are formed from thermoplastic sheet material which comes to 
the wrapping or banding zone in continuous, substantially untensioned webs 
that are drawn off of unbraked supply rolls rotating continuously at 
steady rates. Since the band material is not substantially tensioned at 
the time it is looped around the product, the product must be kept under 
compression during the band forming step, and in fact it should then be 
under more compression than is desired for it in the finished package, so 
that it can subsequently expand into good holding engagement with the 
band. This poses the problem of providing holding means for maintaining 
the product under compression while a band is formed around it and 
cooperating means for so forming the band that the thermoplastic sheet 
material is always under control. Furthermore, the holding means and the 
band forming means must so cooperate that the band and the pack of product 
can eventually be separated from the holding means without also separating 
the product from the band. 
These problems have been very satisfactorily solved in the machine of the 
present invention, but the solutions to these basic problems have brought 
in their train other problems of at least equal difficulty. In particular, 
the general arrangement and functioning of the apparatus contemplated by 
this invention entails a requirement for a very compact cutting and 
heat-bonding means whereby a cut can be made through flatwise superposed 
layers of thermoplastic sheet material and the layers can be substantially 
simultaneously heated-bonded to one another to form seams along both of 
the edges that result from the cut. To be completely satisfactory in a 
machine of the type contemplated by this invention, the cutting and heat 
bonding means must be capable of performing an operation quickly, must be 
able to repeat the operation at short intervals, but must nevertheless 
operate consistently even when there happen to be long intervals between 
successive cutting and heat-bonding operations. This is to say that the 
device should get hot enough to perform a cutting and heat-bonding 
operation in a very brief period of time, but it should nevertheless not 
overheat during the course of a very long delay between operating cycles. 
One type of prior apparatus for performing a severing and seam-fusing 
function, disclosed in U.S. Pat. No. 2,686,556, to Gerber et al, comprised 
a high frequency generator having a frequency range on the order of 10 to 
300 mega-Hertz. That apparatus may have functioned satisfactorily, but it 
would not be well suited to present requirements. In addition to the cost 
and inconvenience of providing the generator itself, its presence is now 
known to mandate costly and inconvenient safety precautions for protection 
of personnel from its high frequency radiations. 
Resistance-heat cutting and heat-bonding devices were disclosed in U.S. 
Pat. No. 3,032,257, to Weber, and in U.S. Pat. No. 3,083,757, to Kraft et 
al; but in each of these a resistance heating element was embedded in a 
rather thick blade body, so that the device lacked the compactness and 
light weight that are important for the purposes of the present invention. 
More important, the heat that was abstracted from the blade body at each 
cutting and seam-fusing operation had to be replaced by conduction through 
the body from the embedded heating element, with the result that the 
device tended to have a slow cycle time; whereas if there was a long delay 
between successive operations the temperature of the blade body and 
heating element would continuously rise. Furthermore, in each of these 
disclosed devices the cutting portion of the blade body was on a narrow, 
sharp-edged, projecting portion of the body that encouraged radiation of 
heat, whereas the seam forming or heat-bonding portions of the body were 
more massive in relation to their surface areas and may well have remained 
hotter than the cutting portion, instead of being cooler than the cutting 
portion as is desired for reliable operation. 
SUMMARY OF THE INVENTION 
The general object of the present invention is to provide simple, 
fast-operating, compact, reliable and efficient packaging apparatus 
whereby a snug band or sleeve of light-weight thermoplastic sheet material 
can be placed around each of a succession of packs or stack-like 
assemblages of a compressible product such as paper towels, paper napkins, 
sponges or the like, to maintain the product under a predetermined amount 
of compression. 
Another general object of this invention is to provide a packaging machine 
that forms packages in which resiliently compressible product is held 
under a predetermined degree of compression by a neat, tough band, said 
packaging machine being capable of operating at high rates of production 
but being nevertheless capable of operating efficiently at any rate slower 
than its maximum, so that it can form packages on demand, when and as 
product is fed to it. 
Another object of the invention is to provide a band packaging machine of 
the character described whereby bands are formed from continuous webs of 
light thermoplastic sheet material that are drawn from supply rolls which 
are unbraked and which rotate continuously at a substantially steady rate 
while packaging is in progress, and whereby the band of each finished 
package is caused to be under tension around a quantity of resiliently 
compressible product, to maintain the product compressed to a 
predetermined extent; said machine being arranged to require a minimum of 
heat energy for forming the bands and none for tensioning them. 
It is also an object of this invention to provide apparatus for 
automatically forming a band around a pack of resiliently compressible 
product while the product is maintained under compression, wherein no 
substantial tension is imposed upon the material comprising the band 
during the time that the band is being formed or during a subsequent 
interval in which its heat-fused seams are cooling, said apparatus being 
so arranged that after said seams have fully cooled, the band and the pack 
are maintained in their desired final relationship to one another while 
they are disengaged from means whereby the pack has been held under 
compression during forming of the band and cooling of its seams. 
Another and more specific object of this invention is to provide apparatus 
for automatically placing a band of light-weight thermoplastic sheet 
material around each of a succession of packs of a compressible product 
such as paper towels, paper napkins or sponges as the packs move along a 
defined path and while each pack is compressively clamped between a pair 
of paddle-like carrier jaws, wherein the thermoplastic material is brought 
to said path in the form of two webs that are guided into said path from 
opposite sides thereof, and wherein the two webs are formed into a band 
for each pack, each band having two seams, one at the front of the pack, 
the other at its rear, the rear seam being formed substantially 
simultaneously with severing of the band from the webs and with connection 
of the webs with one another to provide the front seam for the next pack. 
In connection with the last stated object of the invention it is a further 
specific object of the invention to provide a packaging machine of the 
character described wherein the formation of said two seams and the 
severing of the band from the webs is accomplished quickly and at 
relatively short intervals without imposition of tension upon the 
newly-fused seams, and wherein adequate cooling time is provided before 
tension is imposed upon the seams, but such cooling time is not provided 
at the sacrifice of a high rate of production. 
Another specific object of the invention is to provide a band packaging 
machine of the character described whereby each band is formed from 
material severed from each of two webs and therefore has two heat-fused 
seams, and wherein simple means are provided for ensuring that the two 
pieces of material that comprise each band will be equal in length and the 
seams in the band will be neatly opposite one another and in nicely 
uniform positions on every package. 
It is also a specific object of the invention to provide a very compact, 
inexpensive and light weight resistance-heated element for making a cut 
through flatwise contiguous sheets of thermoplastic material and for 
simultaneously heat bonding the sheets to one another along both sets of 
their edges that result from the cut, said element being one that has a 
short cycle time but nevertheless has no tendency to overheat during long 
delays between successive operations. 
In general, the objects of the invention are achieved in apparatus having 
carrier means comprising carrier jaw members between which a quantity of 
resiliently compressible product is receivable and which are constrained 
to move in a forward direction along a defined path. The apparatus also 
comprises guide means whereby a pair of elongated webs of thermoplastic 
sheet material are guided towards said path from a pair of opposite sides 
thereof; first seam bonding means for forming a first seam that connects 
the adjacent ends of said webs, substantially all across the width of 
each, so that the connected end portions of the webs comprise a band strip 
which extends across said path and which is drawn out into a U-shaped open 
loop that embraces said jaw members as the jaw members move in said 
forward direction; pressure jaw means arranged to converge across said 
path from said opposite sides thereof and by which the opposite legs of 
said open loop are brought into contact with one another behind said jaw 
members; second seam bonding means carried by said pressure jaw members 
for forming a second seam substantially simultaneously with formation of 
said first seam, which second seam is parallel to said first seam, is 
spaced a small distance in said forward direction from said first seam, 
and forms said band strip into a closed band; and cutting means carried by 
the pressure jaw members and arranged to make a cut through the materials 
of both of said webs, which cut is made substantially simultaneously with 
formation of said first and second seams and is between those seams to 
sever said closed band from said webs. 
The cutting and seam bonding means for forming said first and second seams 
and the cut between them is preferably the novel cutting and seam bonding 
means of this invention, which comprises a strip of metal that is of 
substantially uniform thickness substantially all across its width and 
along its length, said strip having lengthwise extending bends which 
define a ridge of substantially V-shaped cross-section that extends along 
the length of the strip intermediate its edges, and which further define 
portions of said strip at opposite sides of said ridge that are 
substantially flat and coplanar with one another. The ends of said strip 
are arranged for connection with terminals of an electric current source, 
for resistance heating of the strip. The strip has its flat coplanar 
portions overlying a substantially flat front surface of a support for the 
strip that is substantially electrically non-conductive but is capable of 
conducting heat, and said support conducts some heat away from said 
coplanar portions so that the apex portion of said ridge, being spaced 
forwardly from said front surface, is normally the hottest portion of said 
strip.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION 
Referring now to the accompanying drawings, the machine of this invention, 
in its preferred form, comprises a disc-like turret or turntable 5 which 
is mounted on a machine frame 6 for rotation about an axis that is 
preferably horizontal. Spaced around the turret 5 at regular 
circumferential intervals are pairs of carrier jaws, each pair consisting 
of a relatively fixed jaw 7 and a relatively movable jaw 8. Both carrier 
jaws are elongated and paddle-shaped, and both project lengthwise 
forwardly from a front face of the disc-like turret 5. 
The fixed jaw 7 of each carrier jaw pair is secured directly to the turret 
5, whereas the movable jaw 8 is carried at one end of a lever arm 9 that 
has a pivotal connection 10 to the turret 5 and overlies its front face, 
so that swinging of the lever arm 9 carries the movable jaw 8 toward and 
from the cooperating fixed jaw 7. The carrier jaws 7, 8 are preferably 
oriented with their broad surfaces facing substantially circumferentially 
relative to the turret 5, and they thus flatwise oppose one another to 
cooperate in carrying a stacked pack 11 of paper towels or paper napkins 
or pack of sponges or of a similar resiliently compressible product. 
The turret 5 is indexingly rotated (counterclockwise, as shown in FIG. 1), 
as by means of a known indexing drive 12. The turret 5 thus comprises a 
carrier where-by each pair of carrier jaws 7, 8 is intermittently 
transported along a defined path which is in this case a circular orbit. 
Each indexing motion brings one of the pairs of carrier jaws 7, 8 to a 
loading station 14 at which a pack 11 of product is inserted between the 
jaws by loading mechanism 15 that is described hereinafter. The next 
indexing motion carriers the newly-loaded pair of carrier jaws 7, 8 to a 
banding station 16, also described hereinafter, at which a band 17 of 
light thermoplastic sheet material is formed around the jaws and the 
product pack 11 between them. Two webs 19, 20 of thermoplastic sheet 
material, equal to width, are cut and fused across their widths to form 
the band 17, and the segments of those webs that comprise each band are 
connected by two heat-bonded seams 22, 23 (best seen in FIG. 9). 
During several subsequent indexing movements of the turret 5, the seams 22, 
23 on the band 17 are permitted to cool as the banded pack 11 is moved 
orbitally towards an unloading station 25; and when the banded pack 
reaches that station, it and its band 17 are pushed axially forwardly off 
of the carrier jaws 7, 8 by an unloading mechanism 26. Subsequent indexing 
movements of the turret 5 bring the carrier jaws 7, 8 back to the loading 
station 14 and through a repetition of the cycle. 
The product packs 11, which have been made up in a known manner, are 
brought to a location which is, in this embodiment, behind and below the 
loading station 14 of the machine. The loading mechanism 15 at the loading 
station 14 comprises a bifurcated transfer arm 28 (FIG. 2) that is 
swingably mounted on the back of the machine frame 6 and is swung up and 
down by a double-acting cylinder actuator 29 that is connected between it 
and the machine frame 6. The loading mechanism 15 also comprises a pusher 
30 that is moved forwardly and rearwardly by another double-acting 
cylinder jack 31. The cylinder jacks 29 and 31, as well as other cylinder 
jacks identified hereinafter, are preferably pneumatic. 
In the lowered loading position of the transfer arm 28, in which it is 
shown in FIG. 2, a somewhat compressed pack 11 of product is inserted 
between its bifurcations in a known manner, and the transfer arm is then 
swung forwardly and upwardly by its actuator 29 to bring the pack to a 
position (FIG. 13) rearwardly in line with the pair of carrier jaws 7, 8 
at the loading station 14. The pusher 30 then moves the pack 11 in an 
axially forward direction, to insert the pack between the jaws 7, 8, 
bringing the pack to the position shown in broken lines in FIG. 13. To 
permit the product pack 11 to pass through the disc of the turret 5 in 
moving forwardly into the grip of the carrier jaws 7, 8, the peripheral 
portion of the turret has a cut-out or bay 32 at each pair of carrier 
jaws. 
As carried by the jaws 7, 8, the products in the pack have their front 
edges substantially flush with the front edges of the jaws. Furthermore, 
it is to be observed that (as best seen in FIGS. 6 and 7) the carrier jaws 
7, 8 are somewhat narrower than the product pack, so that portions of the 
pack project beyond the longitudinal edges of the jaws. 
The loading mechanism 15 can be controlled to operate in response to the 
presence of a pack of product in a zone or location from which the pack is 
fed into the transfer arm 28. The means for effecting such control can 
comprise photoelectric cells (not shown) or other devices of a type that 
will be obvious to those skilled in the mechanical arts, and such persons 
will likewise have no difficulty in arranging suitable means for 
coordinating the operation of the pusher actuating jack 31 with operation 
of the actuator 29 that swings the transfer arm 28. With the provision of 
such control means, the machine can operate on a demand basis, as and when 
packs are fed to it. 
It will be apparent that indexing motions of the turret 5 must be 
coordinated with operation of the loading mechanism 15, and that the 
operation of certain other components of the machine, including the 
unloading mechanism 26, must in turn be coordinated with turret indexing 
motions. Again, the provision of suitable instrumentalities for effecting 
such coordination is well within the ordinary abilities of those skilled 
in the art. However, it might be mentioned that in the preferred form of 
the machine, the indexing drive 12 for the turret 5 is of a commercial 
type wherein a continuously running motor is connectable with the indexing 
drive mechanism through an electric clutch-brake that is energized for 
effecting each indexing advance of the turret; and in that case, 
energization of the electric clutch-brake is coordinated with operation of 
the loading mechanism 15. 
At the loading station 14 the carrier jaws 7, 8 are in a relatively 
diverged condition, being spaced apart by a slightly greater distance than 
the distance between the bifurcations of the transfer arm 28, so that the 
pack 11, while being maintained under substantial compression, can readily 
be slid forwardly from the grip of the transfer arm into the grip of the 
carrier jaws. As the turret 5 carries the pack-carrying jaws 7, 8 towards 
the banding station 16, the jaws are converged to further compress the 
pack of product that they carry. When the band 17 is initially formed at 
the banding station 16, it fits slackly around the carrier jaws 7, 8 and 
the pack 11 between them; and as the jaws move away from the banding 
station they are diverged just enough to take up the slack in the 
newly-forward band 17 without tensioning it. The carrier jaws 7, 8 then 
maintain their relative positions through several subsequent indexing 
movements, to allow time for cooling of the heat-fused seams 22, 23 of the 
newly-formed band 17. As the jaws 7, 8 approach the unloading station 25 
they are further diverged, to somewhat relieve compression on the pack 11 
between them while tensioning the band 17. Such tensioning brings the 
stretches of the band that bridge the jaws 7, 8 into firm engagement with 
the portions of the pack that project beyond the longitudinal edges of the 
jaws, so that the band 17 and the pack 11 tend to move in unison as they 
are slid axially forwardly out of engagement with the jaws 7, 8 at the 
unloading station 25. The pack 11 is therefore within the embrace of the 
band 17 as the pack and the band leave the carrier jaws, and the pack 
expends to fill and tension the band. 
The unloading mechanism 26 (FIG. 1) at the unloading station 25 comprises a 
pusher 34 that is actuated by a double-acting cylinder jack 35. The 
unloading movement of the pusher carries it forwardly between the carrier 
jaws 7, 8, all the way to their front edges, and as it moves forward it is 
engaged with both the pack 11 between the jaws and the band 17 around 
them. 
The above described divergence and convergence of the carrier jaws 7, 8 is 
due to controlled movement of the lever arm 9 that carries the movable 
member 8 of each carrier jaw pair. Each such lever arm 9 is part of a bell 
crank (FIG. 15) that further comprises another lever arm 37 which carries 
a cam follower roller 38 at its outer end. The several cam follower 
rollers 38 cooperate with a face cam 36 (FIG. 16) that is coaxial with the 
turret 5 but is confined against rotation, riding in the groove 36' of 
that cam. 
Each fixed carrier jaw 7 is mounted on an L-shaped bracket 40 that is 
secured to the turret 5, and the movable jaw 8 is similarly connected to 
the lever arm 9 by means of an L-shaped bracket 41. It will be apparent 
that the distance between the carrier jaws 7, 8 can be adjusted to 
accommodate packs of different thicknesses by the insertion of shims 
between the brackets 40, 41 and the respective jaws 7, 8 carried by them. 
As a pair of carrier jaws 7, 8 approaches the banding station 16, it is 
moving towards what is, in effect, a continuous strip of thermoplastic 
sheet material that extends across its path. In fact that strip comprises 
the connected end portions of the two webs 19, 20, which webs are 
respectively guided towards the path of the approaching carrier jaws from 
opposite sides of that path. The web 19 is drawn off of a supply roll 43 
(FIGS. 1 and 14) that is mounted on the machine frame 6 for unrestrained 
rotation about an axis which is fixed at a substantial distance radially 
outwardly from the periphery of the disc-like turret 5. After leaving the 
supply roll 43, the web 19 zig-zags through the rollers of a generally 
conventional festoon or take-up device 44 that allows the supply roll 43 
to be unwound at a relatively steady rate of rotation even though the free 
end of the web 19 is advanced at rather substantially varying rates. 
The other web 20 is drawn off of a freely rotatable supply roll 45 that is 
mounted coaxially with the turret 5, and the web 20 likewise passes over a 
festoon or take-up device 46. 
The mounting means for each of the supply rolls 43, 45 includes means 
comprising a double-acting cylinder jack 47 for adjusting the axial 
position of the roll so that its web will track properly with the other 
web and with the path of the carrier jaw pairs 7, 8. It will be understood 
that the tracking adjustment jacks 47 are actuated in response to suitable 
sensors (not shown) which monitor the edgewise positions of the webs. 
For each of the webs 19, 20 there is a pair of guide rollers 48, the 
respective pairs of guide rollers being located at opposite sides of the 
path along which the carrier jaws 7, 8 move, and closely adjacent to that 
path. Each web 19, 20 thus extends from its supply roll 43, 45, through 
its take-up device 44, 46, then to and around its pair of guide rollers 
48, and thence across the path of the carrier jaws 7, 8 to its seam 
connection 22 with the other web. Each of the rollers of each guide roller 
pair 48 rotates on a fixed axis and is equipped with a one-way clutch of a 
known type that allows it to rotate freely in the direction of advance of 
its web 19, 20 but prevents it from rotating in the opposite direction in 
response to the longitudinal tension force exerted upon its web 19, 20 by 
its take-up device 44, 46. 
In addition to the two sets of guide rollers 48, the apparatus at the 
banding station 16 includes a pair of reciprocating members 50, 51 that 
comprise pressure jaws whereby the connected webs 19, 20 are formed into a 
band 17 around each pair of carrier jaws 7, 8 that passes the banding 
station 16 and whereby the material comprising each such band is severed 
from the remainder of the webs 19, 20 at the same time the the webs are 
reconnected with one another to provide for formation of the next band. 
The pressure jaw member 50 comprises an electrically heated cutting and 
heat-bonding element 53, while the cooperating pressure jaw member 51 
comprises a resilient pressure reaction member 54. Each of the pressure 
jaws 50, 51 is elongated in the direction widthwise of the webs 19, 20 and 
has a length to extend completely across the webs. The path of 
reciprocation of the pressure jaws 50, 51, which is substantially normal 
to the path of the carrier jaws 7, 8, is spaced from the guide rollers 48 
by a small distance in the direction of indexing motion of the carrier 
jaws. 
As a pair of carrier jaws 7, 8 approaches the banding station 16, the 
pressure jaws 50, 51 are in their diverged or retracted positions shown in 
FIGS. 2 and 4, clear of the path of the carrier jaws. The carrier jaws 7, 
8 can therefore move into engagement with the strip of thermoplastic 
material which extends across their path between the sets of guide rollers 
48 and which comprises the connected end portions of the webs 19, 20. As 
the pair of carrier jaws 7, 8 continues its advance, it cooperates with 
the sets of guide rollers 48 to draw out that strip into a U-shaped loop 
43 (FIGS. 1 and 6) that embraces the carrier jaws and the product pack 11 
between them. In the final stage of the drawing-out of this U-shaped loop 
43, the legs of the loop come into contact with control bars 57, 58 on the 
respective pressure jaw members 50, 51. 
When the pair of carrier jaws 7, 8 has moved all the way to its 
banding-station position (FIG. 6), the pressure jaws 50, 51 move towards 
one another behind the fixed carrier jaw 7. Such convergent motion of the 
pressure jaws 50, 51 brings together the legs of the U-shaped loop 43 so 
that it now completely surrounds the carrier jaws 7, 8 as well as the 
product pack 11 carried by them. The two layers of thermoplastic material 
thus brought together by the pressure jaws 50, 51 are clamped between the 
electrically heated element 53 and the resilient pressure reaction member 
54 (FIG. 7). The electrically heated element 53 is so arranged (as 
explained hereinafter) that by reasons of its heat and the clamping force 
exerted by the pressure jaws 50, 51, a cut 59 is made through both layers 
of plastic, all across the width of each, and simultaneously the two 
layers are heat-bonded to one another along both sets of their edges that 
result from the cut 59, so that such heat bonding produces the two fused 
seams 22 and 23. The seam 23, which is directly adjacent to the fixed 
carrier jaw 7, connects the ends of the plastic loop 43 that has been 
formed around the pack 11 and the carrier jaws 7, 8, so that said loop 
becomes a complete closed band 17. By reason of the cut 59 that has been 
made through the two layers of plastic, the newly-formed band 17 is 
severed from the two webs 19, 20. The other seam 22 constitutes a new 
connection between the free ends of the webs 19, 20, providing a new strip 
extending between the sets of guide rollers 48, ready to be drawn into a 
U-shaped loop by the next carrier jaw pair 7, 8, in a repetition of the 
banding operation just described. 
When formation of the band 17 is completed and the pressure jaw members 50, 
51 move back to their diverged (FIG. 1) positions, clear of the path of 
the carrier jaw pairs, the band 17 fits somewhat loosely around the 
carrier jaws 7, 8 and the pack 11 between them, as will be apparent from 
consideration of FIG. 7. It is for this reason that the jaw control cam 36 
causes the movable carrier jaw 8 to move slightly away from its 
cooperating fixed jaw 7 as the carrier jaw pairs moves away from the 
banding station 16, to take up the slack in the band 17 without imposing 
any substantial tension upon it that might break its seams 22 and 23, 
which are still hot and soft. 
As the carrier jaws 7, 8 approach the unloading station 25, the seams 22 
and 23 have been cooled nearly to ambient temperature, and the movable 
carrier jaw 8 is further diverged from the fixed jaw 7, to place the band 
17 under definite tension and bring substantial portions of the band into 
firm engagement with the pack 11, as explained above. 
Returning now to a more detailed consideration of the cutting and bonding 
means of this invention, the electrically heated element 53 is a metal 
strip or flat wire which has its opposite ends connected with the 
terminals of a current source, as by means of conductors 60 (FIG. 4). A 
suitable material for the strip 53 is a nickel-chromium alloy such as is 
commonly used for electric resistance heating elements. Since the strip 53 
is only very briefly engaged with thermoplastic material during each 
severing and seam-fusing operation, it is preferably fed with direct 
current, to ensure that its temperature will be the same from operation to 
operation. 
The strip or heated element 53 has bends along its length that define a 
medial narrow ridge 61 of V-shaped cross-section. That ridge 61 projects 
fowardly beyond flat, coplanar side portions 62 that constitute the 
remainder of the strip, and it forms a cut 59 while the coplanar portions 
62 form the seams 22, 23. Backing up the strip 53 so that pressure can be 
applied through it is a long, narrow channel-shaped member 63, preferably 
of aluminum, having a uniform U-shaped cross-section along substantially 
its entire length. This supporting member 63 has an exterior coating 64 of 
a material, such as ceramic, which is substantially a nonconductor of 
electric current but is a reasonably good conductor of heat. The coating 
64 covers at least the bight portion of the U-section supporting member, 
but preferably, as shown, it also extends over its legs, which project 
rearwardly from its bight portion. As explained hereinafter, the 
supporting member 63 is cooled, as by a flow of air through its interior 
that is preferably interrupted during each sealing operation. 
Since the heated metal strip 53 has a substantially uniform thickness all 
across its width and all along its length, it tends to be heated uniformly 
by current flowing through it. However, its coplanar side portions 62, 
which are in flatwise contact with the flat front surface of the 
supporting member 63, give up a certain amount of heat to that supporting 
member and therefore remain at a somewhat lower temperature than its 
V-section ridge protion 61, which is spaced forwardly from the supporting 
member 63 (as best seen in FIG. 12) and is therefore not in direct heat 
transfer relationship to it. The ridge 61 is therefore hot enough to cut 
quickly through the thermoplastic material, while the cooler coplanar 
portions 62 merely soften the material sufficiently to form the fused or 
heat-bonded seams 22, 23 at opposite sides of the cut 59 produced by the 
ridge. It will be apparent that the U-section member 63 serves as a heat 
sink as well as providing support for the heated element 53. 
In addition to being hotter than the coplanar portions 62, the ridge 61 
also exerts more pressure on the plastic material than said coplanar 
portions, and such higher pressure also helps to account for the ability 
of the ridge 61 to cut through thermoplasic material. This pressure 
relationship is due to cooperation of the heated element 53 with the 
resilient pressure reaction member 54 into which the ridge 61 penetrates 
(FIG. 12) to make the cut 59, while the seam-forming portions 62 of the 
strip cooperate with opposing substantially undeformed portions of the 
surface of the resilient member 54 to form seams 22, 23. 
The front surface of the metal strip 53 can be covered with a thin tape 66 
of high-melting point plastic (e.g., Teflon) that prevents the 
thermoplastic material from sticking to it. The pressure reaction member 
54 is preferably of silicone rubber or a similar material that separates 
readily from softened plastic, or it too can be overlain by a suitable 
high-release tape. 
As best seen in FIG. 4, the two pressure jaw members 50, 51 are carried for 
reciprocation on a plate-like U-shaped bracket 67 on the machine frame 6, 
which straddles the path of the carrier jaw pairs 7, 8 and on which there 
are fixed, parallel guide shafts 69, 70 that extend in the directions of 
reciprocation of the pressure jaw members. Each of the pressure jaw 
members 50, 51 comprises a bar-like carriage member 150, 151, 
respectively, having ball bushings 68 on its opposite ends that ride on 
the guide shafts 69, 70. For each of the bar-like carriage members 150, 
151 there is a double-acting pneumatic actuator comprising a cylinder 72 
that is affixed to the U-shaped bracket 67 and a piston that has its rod 
73 connected to the carriage member. 
Supports 74 for the guide shafts 69, 70 can comprise stop abutments which 
define a limit of inward motion of one of the pressure jaw members--e.g., 
the pressure jaw member 51 that carries the resilient pressure reaction 
member 54. The air fed to the actuator 72, 73 for that pressure jaw member 
51 is at somewhat higher pressure than air fed to the other pressure jaw 
member 50 so that the pressure jaw member 51 is caused to move faster than 
the cooperating member 50 and is brought into engagement with the 
abutments 74 before the cooperating member 50 finishes its stroke. As a 
result, the pressure jaw member 51 is always in a position defined by the 
abutments 74 whenever the other pressure jaw member 50 comes into clamping 
relationship to it for seam bonding, and consequently all bands formed by 
the machine have their respective seams 22, 23 uniformly located in 
relation to the packs 11 that they surround. In addition, the front seam 
22 that is formed at each convergence of the pressure jaws 50, 51 
maintains its position relative to the path of the packs 11 because 
neither of the webs 19, 20 can be drawn lengthwise rearwardly by tension 
in its takeup device 44, 46, owing to the one-way clutches associated with 
the guide rollers 48. These one-way clutches also prevent tension from 
being imposed upon newly-fused front seams 22. 
The bar-like carriage member 150 on which the heated element 53 is carried 
has a lengthwise extending forwardly opening groove in its front end in 
which the supporting member 63 is received with a close fit. The 
supporting member is readily detachably held in this groove by means of 
clips 76 at opposite sides of the carriage member 150, secured to the 
latter by means of screws 77 that are received in threaded holes in the 
carriage member. The clips 76 engage in longitudinally extending grooves 
78 in the opposite sides of the supporting member 63. 
Because of the U-shaped cross-section of the heat sink supporting member 
63, it cooperates with the carriage member 150 that carries it to define 
an air channel 80 in which cooling air flows. Bores 81 in the carriage 
member 150, openig to the channel 80, provide passages through which 
cooling air can be fed into this air channel and exhausted from it, to 
provide for a constant flow of cooling air in contact with the supporting 
member 63. 
End portions of the electrically heated strip 53 project beyond the 
supporting member 63 to be received in connector blocks 84 whereby the 
strip 53 is detachably mounted on the carriage member 150 and is 
electrically connected to the conductors 60. Each connector block 84 has a 
slot through which its end portion of the strip 53 extends, and a set 
screw 85 that is threaded into the connector block secures the strip 53 to 
the block 84 and provides for a good electrical connection with the 
conductor 60. 
Each of the connector blocks 84 has a pivotal connection 87 with the 
carriage member 150, about which the connector block can swing in 
directions lengthwise of the strip 53, toward and from its adjacent end of 
the supporting member 63; and an expansion spring 88, reacting between 
each connector block 84 and the carriage member 150, biases the connector 
block away from the adjacent end of the supporting member 63 to maintain 
the metal strip 53 under lengthwise tension. 
The slot in each connector block 84 is so located as to dispose the end 
portion of the strip 53 in rearwardly offset relation to the plane of the 
flat front surface of the supporting member 63; hence, the lengthwise 
tension that is imposed upon the strip 53 by the springs 88 holds the 
strip with its coplanar seam-forming portions 62 in good flatwise heat 
transferring engagement with the supporting member 63. 
The resilient pressure reaction member 54, which can be of square or 
rectangular cross-section, is held in place on the front of the carriage 
member 151 by means of parallel side plates 82 that are detachably secured 
to opposite sides of that carriage member. Each of the side plates 82 has 
an inturned edge portion that projects a little distance laterally 
inwardly across the working face of the pressure reaction member 54 to 
secure it to the carriage member 151. 
At each side of the pressure jaw member 50 that comprises the heated 
element 53, there is a web detaching bar 57 that slidingly engages the web 
20 during converging motion of the pressure jaw members. Each of the web 
detaching bars 57 comprises the straight, elongated bight portion of a 
U-shaped member which can be bent from rod stock or heavy wire and which 
has parallel legs 90 that are slidably received in tubular guides or 
holders 91 fixed to opposite sides of the carriage member 150. A coilded 
compression spring 57a surrounds each leg 90 and reacts between its 
holders 91 and a collar 57b on the leg, to bias the bar 57 towards a 
normal extended position in which it is shown in FIG. 10 
The other pressure jaw member 51 likewise carries a pair of web detaching 
bars 58, one at each side of it, in forwardly lengthwise spaced parallel 
relation to the pressure reaction member 54. As shown, the web detaching 
bars 58 comprise U-shaped members having their parallel legs 90a fixed in 
tubular holders 91a on the carriage member 151. It will be evident that 
the web detaching bars 58 could be mounted for extending and retracting 
movement relative to the carriage member 151, in correspondence with the 
mounting of the web detaching bars 57 on the carriage member 150. 
It will be evident that when the web detaching bars 57 are in the normal 
positions to which they are biased, they cooperate to define a plane that 
is spaced ahead of the electrically heated element 53; and the web 
detaching bars 58 similarly define a plane which is spaced forwardly of 
the pressure reaction member 54. Furthermore, the respective bars 57 and 
58 are opposite one another, so that in the last stages of convergence of 
the pressure jaw members 50, 51 the bars 58 force the bars 57 to retract, 
compressing the springs 57a. As the pressure jaw members 50, 51 move apart 
at the conclusion of a cutting and seam bonding operation, the bars 57 
advance relative to the jaw member 50, moving back toward their normal 
position, and they thus detach the web 19 from the heated element 53 in 
case the web has any tendency to stick to it. It will be apparent that 
during the initial stages of convergence of the pressure jaw members 50, 
51 the web detaching bars 57 on the jaw member 50, which are then in their 
normal positions, prevent the material of the web 19 from contacting the 
heated element 53. 
From the foregoing description and the accompanying drawings it will be 
apparent that this invention provides a machine for forming a band of 
light thermoplastic material around resiliently compressible product such 
as a stack of paper towels or paper napkins, and that the machine of this 
invention comprises a simple, inexpensive and highly effective 
electrically heated element whereby a cut can be made through plural, 
flatwise superimposed layers of thermoplastic sheet material and, 
simultaneously, heat-bonded seams can be formed along the respective edges 
of the sheets of material at each side of the cut.