Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to packaging apparatus and more
particularly to the cut off mechanism of a wrapper by which a
film in substantially tubular ~orm embraces spaced articles or
containers moving along a conveyor line wherein the tubular
wrapper is severed and closed as by sealing between the spaced
articles.
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Tubular film wrappers are most oftsn made of heat-sealable
material such as polyethylene film, or a wide variety of other
heat-sealable plastics; however, in certain situations, the
material of the film may be sealable to itself without applica-
tion of heat, and sealable mexely by application of pressure.
The film materials will vary over a wide range in thickness,
dependlng upon the necessary strength of the material in the
wrapper and the nature of the article or goods being packaged.
The sizes and nature of the articles being packaged also vary
over an extremely wide range, and may in some instances be hard
goods such as tools and machlne parts, and in other instances
may be boxes which contain one or more individual articles; or
in other instances the goods being wrapped may be fragile
articles such as cookies or crackers which produce crumbs during
handling.
Modern wrappers move the film and articles being wrapped
along through the machlne at speeds which are typically in the
range of 50 to 300 inches per minute, and 500 inches per minute
is not particularly excessive speed. Depending upon the size
of the packages being formed, the wrapper will make up to 250
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packages per minute, each of which must be cleanly cut from the
tube film between the spaced articles being wrapped. Of course,
the ends of the packages being formed are also sealed closed at
the same time the cuttlng is effected.
In the prlor art, the plastic wrapper has been cut in
several ways. In one type of cutting arrangement, the tubular
film wrapper with the articles enclosed therein passes between
revolving shafts which carry crimper~ or sealers for sealing the
ends of the packages as they are being cut. A knife which is
confined in a slot in one of the crimpers is momentarily project-
ed out of the slot to sllce through the film as the crlmpers
engage and seal the fllm closed. The knife which moves radially
with respect to the shaft moves into a slot in the other crimper
as it completes the cutting operation, and then the knife is
quickly withdrawn to be ready for the next cutting operation.
Although this type of reciprocating knife arrangement is widely
used, it is complicated and expensive to build and maintain.
Another type of cutting arrangement in the prior art
uses the similar revolving crimpers as described above. One of
the crimpers carries a substantially flat and stationary anvil;
and the other of the crimpers carries a knife with a cutting
edge to cooperate with the anvil face for cutting the film moving
between the revolving shafts and crimpers. In this construction,
the proper setting of the location of the knives with respect
to the anvil faces and the proper location of the crimpers with
respect to each other is extremely critical. The knife must be
adjusted with respect to the anvil 50 that the edge of the knife
barely kisses the surface of the anvil without applying any
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excessive pressure. This setting causes the knife to cleanly
sever the thicknesses of the film wrapper. However, the knife
adjustment is very critical; and if the knife is backed away from
the anvil as little as 0.001 inch, the cut off of the film wrap-
per will not be reliably complete. A mere change in the heat
conditions in the crimper which mounts the knife and anvil may
; change the optimum setting of the knife. Decreasing the heat in
the crimper will cause the kni~e to back away from the anvil due
to metal contraction, thereby preventing good and clean cut off.
An increase in the heat will cause interference between the
knlfe and anvil, resultlng in abnormally high wear on the sharp
knife edge.
In this prior art cut off arrangement wherein the knife
is stationary with respect to the revolving shaft, and the anvil
is also statlonary with respect to the adjacent revolving shaft,
the wrapping machine may requlre a new knlfe or a reground knife
approximately every month of operation in order to assuredly
cleanly cut each package from the tube of film stock moving
through the wrapping machine, Obviously, as the knives must be
2~ replaced and readjusted, the machine must be shut down with the
associated loss of very valuable production time. In situations
where short packages are being wrapped, two or four separate
crimpers and cut off knives are carried on one of the shafts
and corresponding two or four crimpers and anvils are carried on
the other shaft.
One other problem that is encountered in this type of
cut off mechanism is the presence of obstructions in the cut
off or seal area. Such obstructions may be cookie crumbs or
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small particles of material, or may be a wrinkled ilm, so as to
increase the spacing between the crimpers adjacent the knives.
If a crumb or particle is in the crimper area, the crimpers will
be moved apart slightly during the crimping and cut off operation
due to movement of one of the shafts against the springs pressing
its bearings toward the optimum position. When the crimper and
knife are moved away from the other crimper and anvil, obviously
a complete cut off cannot be attained.
Summarv of the Invention
An object of the invention is to provide a cut off and
crimping mechanism for a tubular film wrapper which will reliably
sever individual packages from the rapidly moving tube of film
material which embraces the articles or goods being wrapped.
Another object of the invention is to provide a cut off
and crlmping mechanism for a tubular film wrapper which will
reliably sever the individual packages from the rapidly moving
tube of fllm wrapping material and which will materially extend
the life of the cutting blades which are used in severing the
film.
A feature of the invention is to yieldably mount the
anvil on springs in the revolving crimper which cooperates with
the opposite revolving crimper which carries a stationary knife
cooperating with the anvil in severing the film passing between
the crimpers and associated knife and anvil.
Another feature of the inventlon is the yieldably mounting
of one of the knife and anvil which are respectively disposed in
opposite and cooperating revolvi g crimpers ~or closing the ends
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of packages being severed from a high-speed moving tubular film,
wherein one of the crimpers is yleldably mounted with respect to
the other to accommodate limited variation in the thickness of
the film and other obstructions therebetween during the sealing
and cut off operation.
The particular advantage of the present invention is to
reliably sever the tubular film wrapper at operating speeds
necessary for modern commercial production and to avoid the
interference of small particles or other obstructions that may
exist in the seal area and also extend the life of the cutting
blades used to produce the cutting of the film.
Brief DescriPtion of the Drawings
Figure 1 is an elevation view of the crimping and cut
off mechanism for the packaging machine.
Figure 2 is a side elevation view of the cut off and
crimping mechanism.
Flgure 3 is an enlarged detail section view taken
approximately at 3-3 in Figure 1 and illustrating the crimper
and cut off mechanism at the moment of cutting the film passing
therethrough.
Figure 4 is a detail section view, similar to Figure 3,
and ~howing the crimper and cut off mechanism at a moment sub-
sequent to complete cut off,
Figure S is an enlarged detail view of one of the
crimpers with the anvil mounted therein.
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Detailed Specifi_ation
One form of the invention is illustrated in the drawings
and is described herein.
The wrapper cutting and closing mechanism is indicated in
general by numeral 10, and includes upright frame members 11 which
mount bearing blocks 12 and 13 respectively mounting rotatable
shafts 14 and 15. The lower bearing blocks 12 are affixed to the
frame as by cap screws 12.1 to predetermine the location of the
shaft 14. The upper bearing blocks 13 are slidable along the
inner edges 11.1 of the frame which define a guideway so that the
shaft 15 may be moved slightly away from shaft 14 during opera-
tion. Each of the movable bearing blocks 13 is urged downwardly
by a spring 16, and an adjustable spacer may be provided for
maintaining the minimum spacing between the shafts 14 and 15 and
to resist the downward urging of the springs 16. A spring anchor
mechanlsm 17 adjusts the downward thrust on the springs 16 so as
; to establish the resistance necessary to overcome in order to
move the shaft 15 away from shaft 14.
The two shafts 14 and 15 have meshed gears 14.1 and 15.1
which coordinate the rotation of the two shafts. Input power is
supplied to the shafts from a source of rotary power such as
gear 18.
Crimpers 19 and 20 extend along and are affixed to the
shafts 14 and 15, respectively, by cap screws 22. The crimpers
19 and 20 are provided with electric resistance heaters 23 to
produce sealing heat at the film-engaging surfaces 19.1 and 20.1
thereof. In the form shown, the film-engaging surfaces 19.1 and
20.1 of the crimpers have serrations extending transversely
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113~767
across these film-engaging surfaces for producing similarly
shaped crimped surfaces of the film material F at the seal areas
F'.
The upper crimper 20 has an elongate slot 24 extending
substantially throughout the entire length thereof. An elongate
knife blade 25 is confined in the slot 24 and is confined in
stationary relation in the slot 24 as by a plurality of set
screws 26 located at spaced locations along the length of the
blade. It will be recognized that the knife blade 25 has a
cutting edge adjacent the adjoining film-engaging surface 20.1
of the crimper 20. The sharpened edge of the knife blade 25
protrudes slightly beyond the surface 20.1 for efficiently
severing the film F in the crimp area. It has been found prefer-
able to shape the sharpened edge of blade 25 to extend very
sllghtly spirally or helically of the rotation axis of shaft 15,
so as to effectively cause the cutting edge to engage and cut
the plastic film progressively from one end of the blade 25 to
the other end thereof as the shaft and blade revolve.
The other crlmper 19 also has an elongate slot 26 formed
therein and extending along the length thereof. An elongate
anvil blade 27 is confined in the slot 26, but is movable therein
in a direction toward and away from the rotation axi~ of the
shaft 14 and toward and ~away from the film-engaging face 19.1 of
the crimper. The blade 27 has a plurality of apertures 28
therein to recelve hardened steel roll pins 29 which serve to
retain the anvil blade in the slot 26. The roll pins 29 are
confined in apertures 19.2 of the crimper.
It will be recognized that the aperture 28 in the anvil
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1138767
blade 27 is slightly larger than the diameter of pin 29 so that
- the anvil blade 27 may move, to a limited extent, inwardly and
outwardly of the slot 26.
The knife edge-engaging anvil surface 27.1 of the anvil
blade is located approximately at the film-engaging surface 19.1
of the crimper so that the sharpened edge of the knife blade 25
may cooperate with the anvil face 27.1 in severing or cutting
the film between the adjacent articles A confined by the tubular
film.
A plurality of coil springs 30 bear against the rear
edge of the anvil blade 27 and are confined in openings 31 in
the crimper 19. Threaded plugs 32 are threaded into the threaded
periphery of the openings 31 and serve as anchors for the springs
30. It will therefore be recognized that the anvil blades 27 may
be retracted slightly into the crlmper 19 under influer.ce of
pressure from the blade 25, as illustrated in Figure 3, and the
spring 30 will maintain significant pressure against the anvil
blade 27 so that the knife blade 25 and the anvil blade 27 will
cooperate in cutting the plastic f ilm.
In operation, the spacing between the shafts 14 and 15
will initially be adjusted by the adjustable spacers 12.2 be-
tween the bearing blocks 12 and 13 so that the springs 16 will
normally urge the shaft 15 and the crimper 20 into the desired
relationship with crimper 19. The two film-engaging faces 19.1
and 20.1 will allow space for the fi lm F therebetween, but will
apply sufficient heat and pré~sure to the f ilm in order to
produce a good seal in the seal area Fl.
In some instances where a suitable film is utilized,
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heat may not be necessary in order to produce a seal, but
pressure will be applied in order to adhere the film laminae
together. The arcuately rounded shapes of the film-engaging
surfaces 19.1 and 20.1 effectively cause these surfaces to roll
along a short length of the film in the seal area F~ during the
sealing and cutting process, substantially as illustrated in
Figures 3 and 4.
As the film F and articles A are moving in the direction
of arrow D, and the shafts 14 and 15 and the crimpers 19 and 20
are revolving in the direction of arrows b and c, respectively,
the crimpers 19 and 20 will swing toward each other and squeeze
the film into flattened condition in the seal area. The cutting
edge of the knife blade 25 will bear against the film with
significant pressure and will cut through the film as the edge
of the knife blade bears against the anvil face 27.1 of the
anvil blade. During the engagement of the sharpened edge of the
knife blade 25 with the anvil face 27.1 of the anvil blade, the
edge of the knife blade will cause the anvil blade 27 to recede
slightly in groove 26, but the springs 30 will maintain the
desired amount of pressure against the edge of the knife blade
to assure complete cutting of the film.
; Subsequently, as the crimpers 19 and 20 roll past the
dead center position, into the position illustrated in Figure 4,
the film will have been severed as to produce a distinct and
~eparate complete package P sealed entirely shut. The arcuate
; faces 19.1 and 20.1 of the crimpers will gradually separate as
the shafts revolve so as to allow the next article ~ to pass
between the revolving shafts.
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113fl767
Although the specificatlon illustrates only one crimper
on each o the shafts 14 and lS, so as to accommodate articles
of substantial length, it should be understood that, if it is
desired to maintain approximately the same linear film speed
in the direction of arrow D, and if articles of substantially
shorter length are to be packaged, two or more crimpers on each
of the shafts and coordinated with each other may be employed.
For instance, each of the shafts could have a pair of crimpers,
- 10 disposed at 180 degrees with respect to each other; or it may
be desirable to mount four crimpers on each shaft, each orient-
ed at approximately 90 degrees with respect to each other. Of
course, the suitable number of knife blades and anvil blades,
spring-mounted, as illustrated herein, would be carried on the
several crimpers.
It will be recognized that the permitting of the anvil
blade 27 to move slightly in the slot 26 reduces the criticality
of the adjustment as to locatlon of blade 25. The amount of
pressure that is produced between the cuttlng edge of the knife
blade and the anvil face 27.1 is controlled primarily by the
strength of spring 30 and the adjustment thereof produced by the
location of plug 32 in the opening 31.
Accordingly, it will be recognized that, simultaneously
with the sealing of the film into closed condition at the end of
; the packages P being formed, the knife blade and anvil cooperate
to apply the necessary cutting pressure so as to cleanly cut
each package from the tubular film as the film and articles pass
by the cutting mechanism 10.
An additional important function of.the yieldably
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mounted anvil blade 27 becomes apparent when consideration is
given to the packaging of articles which may be brittle and
produce crumbs or debrls inside the package. For instance,
if some type of an abnormality were to occur or exist in the
seal area F' of the film between the film-engaging faces 19.1
and 20.1 of the crimpers, it may be that the predetermined
relation between the two faces 19.1 and 20.1 cannot be maintain-
ed. Such an abnormality in the seal area may be a possible
wrinkle in the film; or may be a piece of debris fractured from
the article being packaged, such as a cookie crumb, if the
articles being packaged are cookies. Other types of debris or
small particles from the material being packaged could also find
its way into the seal area of the film. When such an abnormality
occurs, the crimpers 19 and 20 are rolled into con~ronting rela-
tion with each other in the usual way, but, due to the presence
of the abnormality or obstruction in the seal area, the upper
crimper 20 is lifted slightly so as to be spaced somewhat further
from the face of the lower crlmper 19. This occurs because the
bearing block 13 for shaft 15 is permitted to move slightly
against the pressure of spring 16. Although the prescribed
amount of pressure to be exerted on the film may be reduced
; momentarily, an adequate seal may very likely occur. Further-
more, because the anvil blade 27 is permitted to move, the spring
30 will cause the blade 27 to move outwardly of crimper l9 from
the position illustrated in Figure 3 so as to maintain the pre-
determined degree o~ pressure exerted against the cutting edge
of the knife blade 25. As a result, even though the obstruction
in the seal area caused the crimper 20 to lift slightly off the
crimper l9, the efficient cutting action between the blade 25
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and the anvil blade 27 will occur and the cut will be cleanly
made and without fail. Of course, when the seal area F~ contain-
ing the obstruction moves away from the cut off mechanism 10, the
springs 16 will move the bearing blocks 13 back into predetermin-
ed position and the crimper 20 will be returned to its normal
relation to the crimper 19 for adequately sealing and severing
the next length of film after the shafts and crimpers have made
one more revolution.
Whereas the yieldable blade in this disclosure comprises
the anvil blade, it may be desirable under certain circumstances
that the knlfe blade should be the yieldable part.
It will be seen that this invention provides a cut off
mechanism for a tubular film wrapper wherein both the anvil
blade is yieldable as it engages the edge of the knife blade, and
acting in conjunction with thi~ yieldability ls the yieldability
of the bearlng blocks 13 to permlt the crlmper 20 to move slight-
ly away from the crimper 19 in order to accommodate slight
abnormalities including obstructions in the seal area.
, 20
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