Note: Descriptions are shown in the official language in which they were submitted.
CA 02831272 2013-10-24
RETROFIT OF A FORM-FILL-SEAL MACHINE HEAT STATION
WITH AN ADVANCED ULTRASONIC WELDING KIT
CROSS REFERENCES TO RELATED APPLICATIONS
This application claims priority on U.S. Non-Provisional Application Ser. No.
13/713,237, filed on December 13, 2012, which claims priority on U.S.
Provisional Application
Ser. No. 61/569,916, filed on December 13, 2011, and which is also a
continuation-in-part of
U.S. Patent Application Ser. No. 12/925,652, filed November 26, 2010, titled
"Sonotrode and
Anvil Energy Director Grids for Narrow/Complex Ultrasonic Welds of Improved
Durability,"
with the disclosures of each being incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to improvements in form-fill-seal machines, and
more
particularly to apparatus which are capable of being retrofit onto such
machines to improve the
machine's productivity through replacement of old-technology heat-sealing
elements using a kit
that includes an advanced ultrasonic welding stack and anvil.
BACKGROUND OF THE INVENTION
The packaging of food and other products with a sheet of flexible plastic film
through an
automated process using a machine is typically achieved by butting and sealing
the plastic film
to form a pouch. There are numerous examples of such machines, which are
referred to within
the industry as form-fill-seal machines, and which may be further subdivided
into categories as
being either horizontal, vertical, or rotary form-fill-seal machines. An
example of a horizontal
form-fill-seal machine is shown by U.S. Patent No. 5,826,403 to Haley; an
example of a vertical
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fortn-fill-seal machine is shown by U.S. Patent to 4,117,647 to Rossi; while
an example of a
rotary form-fill-seal machine is shown by 6,212,859 to Bielik.
For a substantial period of time, these form-fill-seal machines utilized heat
elements, such
as the "heated fin wheels" of the Haley device, to seal the package bottom and
its side seam to
create a pouch, and after filling that pouch with product, a final heat
element would seal the top
open end of the pouch to form the package. An early marriage of ultrasonic
welding principles
for sealing of plastic films with a packaging machine is shown by the 1981
U.S. Patent No.
4,288,965 to James, for a "Form-Fill-Seal Packaging Method and Apparatus."
Ultrasonic
welding has since become the preferred method of sealing, because, among other
reasons,
ultrasonic weld times are less than one second in duration, the process lacks
the potential for
damage to the packaging material or product from an excessive application of
heat, for which
traditional heating elements are susceptible, and because the ultrasonic
welding process is much
better suited to seal through contaminants and product, which the heat sealing
process
accomplishes poorly, if at all.
Our above-noted co-pending U.S. Patent Application Ser. No. 12/925,652 for
"Sonotrode
and Anvil Energy Director Grids for Narrow/Complex Ultrasonic Welds of
Improved
Durability," furthers this divide. The technology disclosed therein makes even
more
advantageous the use of ultrasonic welding over heating elements, as it
reduces the necessary
material, by allowing for a narrower weld, while also simultaneously producing
welds of
improved durability, which is highly desirable particularly for the packaging
of liquid, semi-
liquid, and even for the packaging of solids or semi solid products. Of
course, the process could
still be used to produce wider welds, where they may be desired, for example
for aesthetic
purposes, rather than for being needed to produce a stronger, more durable
seal.
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However, while that patent-pending technology may easily be incorporated into
newly
designed form-fill-seal packaging machines, consumers who either recently or
long ago
purchased machines that seal through the direct application of heat have been
at an impasse. The
owner's of those machines do not wish or simply cannot afford the expense of a
new array of
packaging machines, nor can they afford to not produce packaging with the
durability that their
competitors will soon be utilizing through the use of machines incorporating
this new apparatus.
The problem has one added dimension of complexity.
The different types of packaging machines may dictate forming the pouch in
different
stages and at different locations within the machine. In addition, it is
common to have at least
one or even multiple heat seal stations just for the final top end sealing of
multiple product-filled
pouches. Therefore, it is highly desirable to incorporate our patent-pending
ultrasonic welding
technology onto existing machines, but attempts to accomplish such a retro-fit
by package
machine operators has been unsuccessful, because of the space-constrained
volume allocated to
the replacement unit. The current invention discloses an adaptable retrofit
kit and method for
successfully accomplishing retrofitting of the heat station for different
kinds of form-fill-seal
machines.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a means of retrofitting the heat
station of a
form-fill-seal machine with advanced ultrasonic welding equipment.
It is another object of the invention to provide a means of retrofitting a
space-constrained
volume of a form-fill-seal or pre-made pouch type machine with a kit
comprising advanced
ultrasonic welding equipment.
It is a further object of the invention to provide a versatile retrofit kit
for replacing a heat
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station with a kit comprising advanced ultrasonic welding, for either a
horizontal or a rotary type
of form-fill-seal or pre-made pouch type machine.
It is another object of the invention to provide a retrofit kit for advanced
ultrasonic weld
sealing of two or more product pouches simultaneously.
Further objects and advantages of the invention will become apparent from the
following
description and claims, and from the accompanying drawings.
SUMMARY OF THE INVENTION
Advanced ultrasonic welding components of our co-pending application
12/925,652 are
readily incorporated into the design of new form-fill-seal machines, but the
owners of older
machines, which utilize heat-seal stations, were unsuccessful at devising
suitable apparatus and
methods for retrofit of the sealing equipment. A retrofit that adeptly
replaces the older heat sealing
station of either horizontal or rotary form-fill-seal machines, with an
advanced ultrasonic sonotrode
and anvil of our co-pending application, may comprise the following kit: a
housing; a linear rail fixed
to the housing; at least first and second bearing carriages being slidable
upon the rail; and first and
second fluidic muscles. Faeh of the fluidic muscles may be mounted with a
first end being fixed to a
respective housing wall, and a second end being fixed to a respective bearing
carriage. Attachment to
the respective bearing carriage may be through attachment of each muscle to a
respective mounting
member that may be fixed to respective mounting blocks, which are then fixed
to the bearing
carriages. The advanced anvil and sonotrode may be secured to respective
carriages.
Actuation of each carriage may be through the pressurization of the fluidic
muscles, which in
turn causes cyclic expansion of the chamber of each muscle, which is
accompanied by linear
contraction along its length. The contraction of each fluidic muscle causes
simultaneous converging
translation of the first and second mounting members relative to the linear
rail, to cause engagement of
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a surface of the anvil with a surface of the sonotrode. Synchronizing the
electrical power to the stack
to correspond to this period of engagement, permits sealing of pouches that
are moved along a
conveyor or Rotary dial and positioned between the anvil and sonotrode.
Depressurization of the
fluidic muscles causes reverse translation and disengagement of the anvil from
the sonotrode, after
which the conveyor or rotary dial may advance to cause exiting of the sealed
pouch, and positioning
of another unsealed pouch between the anvil/sonotrode combination.
Specially configured in-line arrangements of the anvil/sonotrode, the bearing
carriages, the
first fluidic muscle, and the second fluidic muscle, serve to provide a very
narrow profile, which
permits side-by-side kit installations for a retrofit that accomplishes
duplex, triplex, or more sealing of
pouches on a horizontal machine.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. I is a perspective view of a first embodiment of the main components of
an
advanced ultrasonic welding retrofit kit of the current invention, with a
housing side panel
removed to expose the fluid mechanical muscles therein.
FIG. 2 is a perspective view of the retrofit kit of Figure 1, with the housing
panel shown
installed to enclose the fluid mechanical muscles.
FIG. 3 is an enlarged side view of a second embodiment of the retrofit kit of
the current
invention.
FIG. 3A is a further enlarged view of the retrofit kit of Figure 3.
FIG. 4 is an end view of the retrofit kit of Figure 1
FIG. 5 is a perspective view of the retrofit kit of Figure 3.
FIG. 6 is the perspective view of the retrofit kit of Figure 5, being reduced
in size and
shown with an optional horizontal machine spacer, and with an optional rotary
machine column
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assembly that may be configured with a fixed static height, or an adjustable
height in the vertical
("Z") direction.
FIG. 7 is an exploded view of the parts comprising the retrofit kit, as seen
in Figure 6.
FIG. 8 is a front view of a rotary form-fill-seal machine capable of being
retrofitted with
the advanced ultrasonic welding retrofit kit of Figure 6.
FIG. 9 is a top view of the rotary form-fill-seal machine of Figure 8.
FIG. 10A is a side view of a prior art ultrasonic welding machine.
FIG 10B is a front view of the prior art ultrasonic welding machine of Figure
10A.
FIG. 11 is a detail view of an anvil that is usable with the present
invention, along with
leveling feet and a mounting base that is securable to the housing herein.
FIG. 12 is an exploded view of the anvil, leveling feet, and mounting base of
Figure 11.
FIG. 13 is an exploded view of a converter, a booster, a sonotrode, and an
anvil that may
be used to weld straight patterns using the energy director grids associated
with the present
invention.
FIG. 13A is a side view of one embodiment of a horn containing a series of
slotted
openings.
FIG. 14 is an isometric view of the anvil formed with the energy director
grids associated
with the present invention.
FIG. 15 is a top view of the anvil of Figure 14.
FIG. 16 is a side view of the anvil of Figure 14.
FIG. 17 is an end view of the anvil of Figure 14.
FIG. 18 is an enlarged detail view of anvil of Figure 14.
FIG. 19 is an enlarged detail view of the grid surface of the anvil of Figure
7.
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FIG. 20 is a section cut through the anvil of Figure 7, and is shown rotated
45 degrees
clockwise.
FIG. 20A a section cut through an alternative embodiment of the anvil of the
present
invention.
FIG. 21A is a front view of an alternate embodiment of the horn of the present
invention.
FIG. 21B is a top view of the alternate embodiment of the horn of Figure 10A.
FIG. 21C is a bottom view of the alternate embodiment of the horn of Figure
10A.
FIG. 21D is a side view of the alternate embodiment of the horn of Figure 10A.
FIG. 21E is a section cut through the energy directors of the horn of Figure
10A.
FIG. 21F is a front view of a second alternate embodiment of the horn of the
present
invention.
FIG. 21G is a side view of the alternate horn embodiment of Figure 10F.
FIG. 22A is a section cut through the anvil and sonotrode of the current
invention, shown
prior to engaging work pieces, where the engagement of sonotrode energy
director plateaus are
aligned with and butt against corresponding anvil energy directors plateaus.
FIG. 22B shows alignment of the energy director plateaus of the sonotrode with
those of
the anvil, per the arrangement of Figure 11A.
FIG. 22C is a section cut through the anvil and sonotrode of the current
invention, shown
prior to engaging work pieces, where the engagement of sonotrode energy
director plateaus are
aligned to interlock with the anvil energy directors plateaus.
FIG. 22D shows the interlocking alignment of the energy director plateaus of
the
sonotrode with those of the anvil, per the arrangement of Figure 11C.
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FIG. 23 shows a prior art energy director utilized on work pieces prior to
ultrasonic
welding.
FIG. 23A shows the prior art energy director of Figure 12 after ultrasonic
welding.
FIG. 24 is an exploded view of a portion of an ultrasonic welding machine
comprising a
converter, a booster, a sonotrode, and an alternative grid-surfaced anvil that
may be used to
produce contoured (non-linear) weld patterns.
FIG. 25 shows a second alternative grid-surfaced anvil that may be used to
produce non-
linear weld geometries.
FIG. 26 shows an alternative "dual lane" horn that accomplishes ultrasonic
welding and
accommodates a blade to cut through the center of the welded materials after
welding in
completed.
DETAILED DESCRIPTION OF THE INVENTION
Initial attempts by package machine operators to retrofit existing form-fill-
seal machines
with the ultrasonic welding technology of our co-pending application serial
no. 12/925,652, was
unsuccessful. The volume that could be occupied by the retrofit apparatus was
extremely
constrained. This constraint was exacerbated by the scenario where a duplex or
triplex sealing
operation was required at the heat station. A single large horn and anvil
being moved to engage
each other using conventional actuators were too slow to achieve satisfactory
results or outside
the realm of single width ultrasonic horn technology. Using two different
pairs of horn/anvil
combinations was unsatisfactory because of the difficulty in calibrating
synchronous engagement
of the pairs while the forces generated were too small, and resort to a servo-
motor was
considered for synchronization, but found to be overly expensive for the
application, as it would
diminish its marketability.
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Figure 1 shows a perspective view of a first embodiment of the retrofit kit 10
of the
present invention, which elegantly overcame these obstacles, being shown with
a housing side
panel 23 removed to expose the actuation portion of the invention.
The device utilizes a pair of fluidic mechanical muscles in a specially
created dual linear
mechanism for simultaneous actuation of both the anvil and the
horn/booster/converter stack.
Today's "Fluidic Muscle," as it is commonly termed (along with pneumatic
artificial muscle), is
in part the progeny of an invention by Richard Gaylord. Gaylord, in 1955,
received U.S. patent
No. 2,844,126 for a "Fluid Actuated Motor System and Stroking Device." In
general, a fluidic
muscle may be constructed by wrapping a synthetic or natural rubber tube with
a woven sheath.
This forms an expansible chamber. When a pressurized fluid is applied to the
chamber of the
fluidic muscle, the chamber expands radially and is accompanied by a
corresponding contraction
in its length, resulting in linear motion. Metallic or plastic fittings may be
secured at both ends to
transmit the resultant motion.
The retraction strength of the muscle may be determined by the total strength
of the
individual fibers forming the woven sheath, while its exertion distance may be
determined
according to the tightness of the weave, where a looser weave may allow
greater bulging,
resulting in further twisting of the individual fibers in the weave. Fluidic
muscles for use with the
current invention may be obtained from the Festo Corporation, located in Mt.
Prospect, Illinois
(see www.festo.c,om).
Fluidic muscles are commonly utilized in pairs- one agonist and one
antagonist, where
the antagonist acts in opposition to the motion of the agonist, thereby
mimicking the functioning
of muscles within the human body (e.g., an extensor muscle that opens a joint
and a flexor
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muscle to act in opposition to close the joint). However, in this invention,
the fluidic muscles
operate in a different mode.
In the simplest possible embodiment, a single fluidic muscle may be used to
replicate the
linear motion provided by the press 190 in a typical prior art ultrasonic
welding machine 100,
represented in Figures 13A and 13B. However, in practice, this is not very
conducive to the
successful retrofitting of many form-fill-seal machines, particularly for a
horizontal type
machine. In such machines, because the pouch(s) may translate along a conveyor
towards a heat
station (see e.g., packaging machine 5 in Figure 1 of U.S. Patent No.
5,826,403 to Haley), where
one or more heating elements may converge upon the pouch(s) to seal it, it is
highly desirable to
impart motion to both the anvil and the sonotrode. This dual motion may be set
so as to have the
sonotrode and anvil generally converge at the mid-plane of the opening to
thereat apply pressure
and vibration energy necessary for localized heating and melting of the
plastic film to seal the
opening.
A first embodiment of the present invention is shown by the retrofit kit 10 in
Figure 1
(with a side panel 23 of the housing removed), and is also shown in Figure 2.
The retrofit kit 10,
which may be used in the replacement of one or more heat sealing elements of
either a horizontal or a
rotary form-fill-seal machine, may include a housing having a base 20, a first
end wall 21, a
second end wall 22, a first side wall 23, and a second side wall 24. The
housing may also
comprise a mid-wall 26. Many of these components are common to a later
discussed
embodiment, for which an exploded view is shown in Figure 7, so reference
thereto may be
advantageous. The housing side panels 23 and 24 may be used to enclose and
protect the fluidic
muscles, along with the base 20 and end walls 21 and 22, and in addition, an
optional cover (not
shown) may be used for those reasons as well. Also, side panels 23 and 24 may
serve to add
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structural rigidity to the housing; however, the panels 23 and 24 are not
required for supporting
the functionality of the mechanism, as will be seen hereinafter.
The base 20 may have a first opening 20A and a second opening 20B, both of
which may
be slotted openings. A first mounting member 30 may have a portion being
disposed part-way
through the first opening 20A in base 20. In one embodiment, first mounting
member 30 may
preferably be "L"-shaped, and may have one leg 31 of the "L" protruding up
through the opening 20A
in base 20, and the other leg 32 may be disposed so as to generally parallel
the base 20 of the housing.
The first mounting member 30 may therefore be slidable within the slotted
opening 20A of the base
20 of the housing. A second mounting member 40 may be similarly constructed
with first and second
legs 41 and 42, and be correspondingly disposed so as to be slidable within
the second opening 20B
in the base. The ends of the second legs 32 and 42 of the "L"-shaped mounting
members may
face each other within the kit assembly.
The second legs 32 and 42 of the "L"-shaped mounting members 30 and 40 may
each be
attached to at least one respective bearing carriage, which may be slidable
upon a linear rail. In a
preferred embodiment, a linear rail with four bearing carriages being slidable
thereon may be
used. Linear rails and bearing carriages are commercially available, and may
be obtained from
PBC Linear, in Roscoe, Illinois (see www.pbelinear.com/Pages/Linear-
Components, the
disclosures of which are incorporated herein by reference). A linear rail 50
may be secured to the
bottom of base 20, and may have bearing carriages 51, 52, 53, and 54 being
slidable thereon, as
seen in Figure I. Depending upon the linear rail selected, and the method
utilized for attachment
to the housing base 20, it is possible for the second leg 32 of the "L"-shaped
mounting member
30 to attach directly to the bearing carriages 51 and 52, with the second leg
42 of the "L"-shaped
mounting member 40 attaching directly to the bearing carriages 53 and 54.
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Alternatively, and as may be seen in Figure 8, a split linear rail 50A and 50B
may be
used, with pairs of bearing carriages 51A, 51B, 52A, 5213, 53A, 53B, 54A, and
54B being
slidable upon the rail pair 50A/50B, and with carriages 51A, 51B, 52A, and 52B
being secured to
a mounting block 61, and with carriages 53A, 5313, 54A, and 54B being secured
to a mounting
block 62. As seen in Figure 1, the opening formed between the split rails
50A/50B and bearing
carriage pairs may serve to permit attachment of the second leg 32 of the
first "L"-shaped
member 30 to mounting block 61, and permit attachment of the second leg 42 of
the second "L"
shaped member 40 to mounting block 62. (Note- attachment of any of the housing
components
or other parts described herein may be accomplished using a suitable adhesive
or any mechanical
fasteners know in the art to be appropriate for the materials used, which may
be wood, metal, or
plastic). With the length of the linear split rails 50A/50B selected to span
the slotted openings
20A and 20B in base 20, the first mounting member 30 may thereby be slidable
with respect to the
first end of the housing, being proximate to the housing end wall 21, within
slotted opening 20A. The
second mounting member 40 may thereby be slidable with respect to the second
end of the housing,
being proximate to the housing end wall 22, within slotted opening 20B.
An advanced anvil 12, which incorporates the features disclosed in co-pending
application
12/925,652, may be secured to the mounting block 61. In a preferred
embodiment, an angled
gusset assembly 64 may first be secured to the mounting block 61, and then the
anvil 12 may be
secured to the gusset assembly 64. To accommodate the build-up of tolerances
and to generally
permit adjustments to the precise static positioning of the anvil, the
importance of which is
discussed hereinafter, a base plate 65 may be located between the gusset
assembly 64 and the
anvil 12, and leveling feet may be positioned between the base plate 65 and
the anvil 12.
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An advanced sonotrode 13, which incorporates features disclosed in co-pending
application
12/925,652, may form part of a stack that also includes a booster 14 and a
converter 15. The
advanced anvil 12 and the advanced sonotrode 13 of application 12/925,652 are
described in
detail, later in the specification. The stack may be secured to the mounting
block 62 using upper
and lower clamp blocks 65U/65L that secure the booster, and upper and lower
clamp blocks
66U/66L that secure the converter. The upper clamp blocks 65U and 66U may each
be fixedly
secured to the mounting block 62, and the lower clamp blocks 65L and 66L may
each be
releasably secured to the corresponding upper clamp blocks using set screws
67, to releasably
secure the stack to the mounting block 62.
One embodiment of the leveling feet, base, and anvil is shown in an exploded
view in
Figure 12. In the embodiment of Figure 12, leveling feet 66A, 668, 66C, 66D,
66E, 66F, and
66G are shown prior to being threadably engaged within corresponding threaded
holes in the
anvil 12, after which the anvil and mounting feet may be secured to the base
and to the gusset
assembly 64 using screws 68, as seen in Figure 11 and Figure 3. The degree to
which each of the
mounting feet 66A-66G are threadably engaged therein may be adjusted- inward
and outward- in
order to provide carefully controlled and adequate support across the length
of the anvil 13, so
that its series of energy director grids, as described in co-pending
application 12/925,652, may
properly engage the corresponding series of energy director grids of the
advanced sonotrode 13.
A contact sheet may be utilized between the energy director grids of the
sonotrode and the anvil,
during their engagement, which is discussed hereinafter, to determine if the
engagement is
proper, with adjustments to the leveling feet being made to achieve uniform
contact
therebetween.
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With this arrangement of Figure 1, a first fluidic muscle 16 may have a first
end 16A being
fixed to the second end wall 22 of the housing, and a second end 16B of
fluidic muscle 16 may be
fixed to the first leg 31 of "L"-shaped mounting member 30. A second fluidic
muscle 17 may have a
first end 17A being fixed to the housing mid-wall 26 of the housing, and a
second end 17B of fluidic
muscle 17 may be fixed to the first leg 41 of "L"-shaped mounting member 40.
The fluidic muscles
16 and 17 may preferably be attached as described to also be disposed in-line,
relative to the linear rail
50 and to the anvil 12 and the stack with sonotrode 13. This in-line
arrangement creates an assembly
that possesses a very narrow, though elongated shape, which facilitates
installation of the retrofit kit
into a space constrained envelope currently occupied by the heat seal station
of certain fonn-fill-
seal machines (see generally Figures 3 and 4, which illustrate installation of
a second retrofit kit
embodiment 10A of the present invention onto such a machine).
With the retrofit kit 10 being assembled as described above, and with
pneumatic/hydraulic
tubes being appropriately installed to port pressure to the fluidic muscles 16
and 17, pressurizing of
the first and second fluidic muscles may cause translation of the first muscle
mounting member 30 and
translation of the second muscle mounting member 40, with the translation
being generally
simultaneous and being relative to the linear rail, and with it causing
convergence of the two mounting
member so as to cause engagement of a surface of the anvil 12 with a surface
of the sonotrode 13. A
controller may be used to sequence porting of pneumatic/hydraulic pressure to
the fluidic muscles and
corresponding depressurizing, with the pulsing of electric power to the stack
to cause the mechanical
vibrations that creates friction between the "work piece" materials (the sides
of the open end of the
pouch) to generate heat to melt the contact area therebetween. Depressurizing
of the first and second
fluidic muscles 16 and 17 may cause reverse-translation of the first and
second muscle mounting
members 30 and 40 relative to the linear rail pair 50A/50B to cause
disengagement of (or separation
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between) the engaging surface of the anvil 12 and the engaging surface of said
sonotrode 13, after an
appropriate weld time has elapsed.
The translation of the two mounting members 30 and 40 need not be
simultaneous, but it is
important that the engaging surface of the anvil 12 and the engaging surface
of the sonotrode 13 meet
at a prescribed "mid-plane," where the pouch is positioned. As seen in Fig 7,
a mechanical stop 55
may be used to institute a travel limiting set point so that when the fluidic
muscles are activated, the
anvil and sonotrode will suitably mesh in the middle. Typically the anvil side
reaches the mid-plane
first, since there is less mass to move, and its travel will thereat be
limited by contact with the
mechanical stop 55. The horn side will thereafter come into contact with the
anvil in the middle, as set
by the adjustable mechanical stop 55. Without the adjustments provided by the
mechanical stop 55,
any differential in reaching the pouch may otherwise serve to cause deflection
of the pouch, resulting
in a distorted weld line, and an aesthetically unappealing package. Having two
different sized fluidic
muscles 16 and 17 may require some additional adjustment to the arrangement to
coordinate the
arrival times of the anvil 12 and sonotrode 13 at the plane where the pouch is
to be sealed. If the first
and second fluidic muscles are the same size, certain efficiencies may be
obtained.
A second embodiment 10A of the retrofit kit of the current invention is shown
mounted to a
horizontal form-fill-seal machine in Figure 3 and 4. This installation of the
kit 10A is shown enlarged
in Figures 3A, and has its component parts shown in the exploded view of
Figure 7. The kit 10A may
make use of two identical fluidic muscles 18 and 19, and may therefore be
capable of simultaneous
and equal translation amounts for both the anvil 12 and sonotrode 13, largely
eliminating the need for
adjustments due to different travel distances or times. In Figure 3, it may be
seen that the engaging
surface of the anvil 12 and the corresponding engaging surface of the
sonotrode 13 may each be
located, prior to pressurization of the fluidic muscles and the associated
translation, approximately 0.5
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inches away from the mid-plane at which the pouch to be sealed may ideally be
positioned. Utilizing
the same fluidic muscle 19 for translation of the sonotrode 13 on the slidably
mounted block 62, as the
fluidic muscle 18 for translation of the anvil 12 on the slidably mounted
block 61, may also result in
equal speeds of translation.
Inline positioning of the same fluidic muscles 18/19 may be accomplished, as
seen in Figures
3A and 7 for this second embodiment, by providing a clearance hole 36 in the
first mounting member
35 to permit sliding of the first mounting member relative to the fluidic
muscle 19 without any contact
occurring therebetween, and by providing a clearance hole 46 in the second
mounting member 45 to
permit sliding of the second mounting member 45 relative to the fluidic muscle
18 without any contact
occurring therebetween. Many other aspects of retrofit kit 10A may otherwise
be similarly constructed
to retrofit kit 10. The first end 18A of the fluidic muscle 18 may be secured
to the housing, albeit by
passing through the oversized orifice 46 in the second mounting member 45, and
possibly being with
the use of an extended end fitting 18Ei on the fluidic muscle, with the
fitting having a threaded portion
thereon to which a nut 95 may torqued to secure it to the housing end wall 22.
The second end 18B of
the fluidic muscle 18 may also have an extended end fitting 18E11 with a
threaded portion thereon to
which a nut 95 may be torqued to secure it to the first mounting member 35.
Also, the first end 19A of
the second fluidic muscle 19 may be secured to the housing, albeit by passing
through an oversized
orifice 36 in said first mounting member 35, and possibly being with the use
of extended end fitting
19Ei on the fluidic muscle, with the fitting having a threaded portion thereon
to which a nut 95 may
torqued to secure it to the housing end wall 21. The second end 19B of the
fluidic muscle 19 may also
have an extended end fitting 19Eii with a threaded portion thereon to which a
nut 95 may be torqued
to secure it to the first mounting member 45.
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Retrofit of the advanced technology ultrasonic anvil and sonotrode onto
existing form-fill-seal
machines may require the removal of one or more heat sealing stations and any
associated support
brackets originally used to secure the heat station to a frame of the machine.
The retrofit kit 10 or kit
10A may be supplied for installation thereon. Because of differences in the
frame and other features of
certain machines produced by various manufacturers, a horizontal machine
spacer assembly 80
(Figures 3, 3A, 6, and 7) may be needed to properly position the kit so that
the anvil and sonotrode are
both properly displaced on opposite sides of the theoretical pouch mid-plane,
as the pouches advance
along the conveyor. Also, for a rotary form-fill-seal machine, such as the one
shown in Figures 8 and
9, proper installation of the kit may also require support of the outward
radially located end of the kit,
through the use of a rotary machine column assembly 90.
Each of the kits, as well as the horizontal machine spacer assembly 80 or the
rotary machine
column assembly 90, may require drilling of mounting holes into the frame of
the machine that is to
be retrofitted. As seen in Figure 5, these holes may be located in one of the
housing end walls 21/22 as
pilot holes, which may then be used as a template for drilling common full
size holes in both the kit
and the machine's frame. Thereafter, the kit may be secured to the frame of
either a horizontal or a
rotary form-fill-seal machine using any suitable fastening means known to one
skilled in the art,
including, but not limited to, nuts, lock washers, and bolts.
The advanced anvil 12 and the advanced sonotrode 13 mentioned hereinabove,
were
disclosed within U.S. Application Serial Number 12/925,652, which was
incorporated by
reference into U.S. Patent Application Serial Number 13/713, 237. The detailed
description of
the invention within U.S. Application Serial Number 12/925,652 is therefore
explicitly
incorporated hereinafter in its entirety.
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Ultrasonic welding is a process in which one or more pieces of material, very
often being
plastic material, may be fused together without adhesives, mechanical
fasteners, or the direct
application of heat (which tends to distort larger areas that need to be
welded), by instead subjecting
the materials to high frequency, low amplitude vibrations. The material to be
welded may have an area
where the material or materials are lapped to form a seam that is sandwiched
between what is typically
a fixed or moveable anvil and a fixed or moveable sonotrode.
As stated in the background, ultrasonic welding may be utilized for fusing
metal parts,
however, it is commonly used for the joining of plastic work pieces. The word
"plastic" can refer, in
the mechanical arts, to the stress/strain relationship where strain has
exceeded a material-specific point
at which further deformation results in a permanent change in shape, which is
distinguishable from the
technical description of the material "plastic." Plastic material usually
comprises polymers with a high
molecular mass, and can be combined with other components to enhance the
performance of the
material for specific applications.
Plastic materials fall into one of two categories- thermoplastic (or thermo-
softening plastic)
and thermosetting. A thermosetting polymer can be melted once only to take a
certain shape, after
which it cures irreversibly. Conversely, thermoplastics may be repeatedly
softened or even melted
upon application of sufficient heat. Thermoplastic materials may be further
subdivided, based upon
the structure of the polymer molecule, which determines its melting and
welding characteristics, into
amorphous and semi-crystalline thermoplastics. Some examples of amorphous
thermoplastics are:
acrylonitrile butadiene styrene (ABS), acrylic, polyvinylchloride (PVC), and
polycarbonate (or
Lexanni). Some examples of semi-crystalline thermoplastic materials include:
polyethylene plastic
resin (PE), polypropylene (PP), polyamide (PA), and polyester (linear ester
plastics). The
amorphous thermoplastic materials possess a randomly ordered molecular
structure that is without a
18
CA 02831272 2013-10-24
distinctive melting point, and therefore soften gradually to become rubbery
before liquefying, and also
solidify gradually, with less of a tendency to warp or experience mold
shrinkage. Conversely, semi-
crystalline thermoplastics have a discrete melting point, and require a high
level of heat energy to
break down the crystalline structure, at which melting occurs. The semi-
crystalline thermoplastic
materials, unlike amorphous polymers, remain solid until reaching its discrete
melting temperature,
after which they melt quickly, and also solidify quickly.
Ultrasonic welding may be performed for similar materials, and sometimes even
dissimilar
materials, but to form a molecular bond for dissimilar materials generally
requires chemical
compatibility, meaning that the melt temperatures are roughly within 40
degrees Celsius and have
similar molecular structure. Ultrasonic welding consists of mechanical
vibrations causing friction
between work piece materials that generates heat to melt the contact area
therebetween, which results
in the formation, upon cooling, of a homogenous molecular bond. The process
requires a controlled
amount of pressure to permit the vibrations to cause the friction heating,
with that pressure being
applied between the sonotrode and the anvil, which is the focal point of the
current invention.
The anvil may be secured to an appropriate fixture, while the sonotrode
(otherwise
known as a "horn" within the relevant art) comprises part of the critical
array of equipment in
ultrasonic welding machines known as the "stack." The stack consists of a
converter (also known
as a transducer, but that term sometimes may also imply use as a
sensor/detector), an optional
booster, and the sonotrode. A converter is a device that converts one type of
energy into another
type of energy. Generally, the converter in the stack will either be a
magnetostrictive transducer
or a piezoelectric transducer. A magnetostrictive transducer uses electrical
power to generate an
electro-magnetic field that may cause the magnetostrictive material to
vibrate. With a
piezoelectric transducer, which is commonly used today, the supplied
electrical power is directly
19
CA 02831272 2013-10-24
converted, and more efficiently converted, into longitudinal vibrations. A
piezoelectric
transducer consists of a number of piezoelectric ceramic discs that may be
sandwiched between
two metal blocks, termed front driver and back driver. Between each of the
discs there is a thin
metal plate, which forms the electrode. A sinusoidal electrical signal-
typically 50 or 60 Hertz
AC line current at 120-240 volts- is supplied to the generator or power
supply. The generator or
power supply then delivers a high voltage signal generally between 15,000 and
70000 hertz to
the converter or transducer. The ceramic discs will expand and contract,
producing an axial,
peak-to-peak vibratory movement of generally between 12 to 25 urn, and usually
being at a
frequency of either 20,000 Hertz or 35,000 Hertz, but with an often used
frequency range of 15
kHz to 70 kHz. So, the transducer converts high frequency electrical energy to
high frequency
mechanical motion.
The booster, being used as a mounting point for the stack, is also utilized to
suitably alter
the amplitude of the vibrations created by the transducer prior to being
transmitted to the horn.
The booster may either decrease or increase the amplitude of the vibrations,
with such changes
being known in ratio form as the "gain." A one to three (1:3.0) booster
triples the amplitude of
the vibrations produced by the transducer, while a one to 0.5 (1:0.5) booster
decreases the
vibration amplitude by one-half. Boosters may be substituted in a stack to
alter the gain in order
to be suitable for a particular operation, as differences in the gain may be
needed for different
material types, and the type of work that is to be performed.
The horn is the specially designed part of the stack that supplies the
mechanical energy to
the work pieces. It is typically made of aluminum, steel, or titanium.
Aluminum tends to be used
most often for low volume applications, as aluminum horns wear more quickly
than ones made
of titanium or steel, although some horns may be manufactured with a special
hardened tip to
CA 02831272 2013-10-24
resist local wear. Aluminum horns are also sometimes used when more rapid heat
dissipation is
needed. Additionally, multi-element composite horns may be used to weld parts.
The length of the horn is a key aspect of its design. To ensure that the
maximum
vibration amplitude in the horn is in the longitudinal direction (away from
the booster and
toward the work pieces and anvil), the horn may contain a series of slotted
openings 66 (see
Figure 13A). Also, the horn, like the booster, is a tuned component.
Therefore, the wavelength of
the vibrations and the length of the horn must be coordinated. In general, the
length must be set
to be close to an integer multiple of one-half of the wavelength being
propagated through the
material of the horn. Therefore the horn may be sized to be a half wavelength,
a full wavelength,
or multiple wavelengths in length. This arrangement ensures that sufficient
amplitude will be
delivered at the tip to cause adequate vibrations, in the form of expansion
and contraction of the
horn at its tip, to create the frictional heating necessary for melting of the
work pieces. This
amplitude, for most horns, will typically be in the range of 30-120 pm.
All three elements of the stack- converter, booster, and sonotrode- are tuned
to resonate at
the same frequency, being the aforementioned ultrasonic frequencies. These
rapid and low-
amplitude frequencies, which are above the audible range, may be applied in a
small welding
zone to cause local melting of the thermoplastic material, due to absorption
of the vibration
energy. The application of ultrasonic vibrations may be for a predetermined
amount of time,
which is known as the weld time, or energy, which is known as the weld energy.
Typically, the
welding process generally requires less than one second, for fusing of the
portion of the two parts
on the joining line where the sonic energy is applied. To achieve adequate
transmission of the
vibrations from the horn through the work pieces, pressure is applied thereto
by an anvil
supported in a fixture, and through the use of a press.
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Figures 10A and 10B show an ultrasonic welding machine 100 utilizing the
arrangement
of a converter, a booster, press, and a sonotrode/anvil of the current
invention. The booster 30 is
often the means by which the stack is secured to the press 110, with it
usually being secured to a
flange or some other portion of the press 110. The converter 10 may be
attached to one side of
the booster 30, while the sonotrode (horn) 50 may be attached to the other
side of the converter
to be in proximity to the anvil '70. The material(s) that are to be fused
together may be located
upon anvil 70. A pneumatic system within the press 110 may cause the flange
mounted stack to
be translated downward so as to contact and apply pressure through the
material(s) aga'nst anvil
70, during which time ultrasonic vibrations are emitted by the converter and
resonate through the
booster and sonotrode.
Figure 13 shows a first embodiment of the present invention, where the stack
includes a
converter 10, a booster 30, a sonotrode 50, and an anvil 70 that may be used
to weld straight
patterns. The converter 10 may be comprised of electrical connectors 11, 12,
and 13. The
converter 10 may also comprise a flat surface 15 from which protrudes a
cylindrical connection
means 16 that may be received in a corresponding cylindrical opening 31 in
flat surface 32 of
booster 30, for attachment of the converter to the booster. The booster 30 may
have a flange 33
for use in securing the booster to a press. The booster may have a second flat
surface 35 with a
cylindrical opening 36 therein, to receive a corresponding cylindrical
protrusion 51 of the horn
50. Alternatively, the booster may have a cylindrical protrusion that is
received by a cylindrical
recess 51A, as seen for the alternative sonotrode 50A of Figure 21A. The
cylindrical protrusion
51 of the horn 50 may protrude from a rectangular block, having a. length 53,
a width 54, and a
depth 55. The rectangular block may transition, at the depth 55, into a narrow
rectangular block
having a width 58, and being of sufficient length 59, inclusive of the
filleted transition areas 52,
22
CA 02831272 2013-10-24
=
to create a horn of total length 57. The horn 50 may have a contact surface 56
with a width 58
and length 53 designed for contact with anvil 70.
The anvil 70, which may be seen in figures 1420, is configured to be supported
in a
fixture and be engaged by the surface 56 of sonotrode 50. Anvil 70 may be
comprised of a
mounting platform 71 having a width 72, length 73, and depth 74. The mounting
platform 71
may be used to retain the anvil 70 in the mounting fixture. Protruding away
from the mounting
platform 71 may be a pedestal portion 75 that shares the same width 72 as the
mounting
platform, but may have a length 76 that may be shorter than, and be
approximately centered
upon, the length 73 of the mounting platform 71. The pedestal 75 may narrow,
by a pair of
radiused surfaces 77, into the engagement surface 78.
As seen in the enlarged detail of the engagement surface 78 in Figures 18 and
19, and the
section cut of Figure 20, the engagement surface 78 of the anvil 70 comprises
a specially
constructed interface that is designed for receiving the vibrations emitted by
the sonotrode 50 to
create a narrower ultrasonic weld region which provides greater weld strength
than is created by
two fiat continuous engagement surfaces. The engagement surface 78 comprises a
plurality of
specially crafted energy directors '79, but are not energy directors in the
plain meaning as utilized
within the relevant art. An energy director within the prior art is where the
work pieces
themselves- meaning the parts to be ultrasonically welded- are created such
that one part is flat
and the other part comes to a sharp point (Figure 23). In the case of the
prior art energy director,
with an example being shown by U.S. Patent No. 6,066,216 to Ruppel, the
pointed work piece
was to provide a focal point for vibrations to produce frictional heat, and
thereby provide a
specific volume of melted material to join the two parts (Figure 23A). With
the invention herein,
the anvil and sonotrode may comprise a plurality of specially constructed
energy directors 79 that
23
CA 02831272 2013-10-24
may be arranged into a coordinated three-dimensional grid pattern, being
coordinated between the
sonotrode and anvil, to thereby selectively increase the total surface area of
the anvil that may be
capable of distributing vibrations in a three-dimensional contact pattern of
vibration-transmissive
contact with the sonotrode, and which may also cause a minimal amount of
deformation of the
work pieces during the initial horn-to-anvil engagement (Figure 22). The
deformation may
preferably be limited to a slight amount, and therefore be limited to remain
within the elastic range of
the material. The increase in surface area of contact may depend upon the
width of the plateau
surfaces used, as described hereinafter. The three-dimensional contact pattern
may be ascertained by
reference to Figure 19, and Figures 20 and 22.
The energy directors 79 of the anvil 70 may be regularly spaced apart from
each other, as seen
in Figure 19. The energy directors 79 may preferably be spaced apart in a
first direction that may
parallel the weld line, and be similarly spaced apart in a second direction
away from, or orthogonal to,
the weld line to form the grid pattern. In a first embodiment, each of the
energy directors 79 may
comprise a plateau surface 80 that may be formed by a first angled side
surface 81, a second angled
side surface 82, a third angled side surface 83, and a fourth angled side
surface 84, where the plateau
surfaces 80 may comprise a rectangular-shape that may be oriented at a 45
degree angle to the weld
line. At the meeting of adjacent side surfaces 81 and 82 of adjacent plateau
surfaces 80, there may be a
valley bottom or trough line 87 that may be oriented at a minus 45 degree
angle with respect to the
weld line, and at the meeting of the adjacent side surfaces 83 and 84 of
adjacent plateau surface 80,
there may be a trough line 88 that may be oriented at a plus 45 degree angle
with respect to the weld
line.
The rectangular-shaped plateau surface 80 lends itself very well to two
different types of
repetitive patterned engagement with the sonotrode described hereinafter,
however, other geometric
24
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plateau shapes may also be utilized, which would naturally alter the side-
surface arrangement. Also,
the rectangular-shaped plateau surfaces 80 may each be generally flat,
although contoured plateau
surfaces 80A may alternatively be utilized, along with a filleted or radiused
trough 87A, as seen in
Figure 20A.
In a first embodiment, seen in Figure 20, the energy directors 79 of the anvil
70 may have a
span therebetween of approximately 0,020 inches, and have a depth from the
plateau surface 8010 the
troughs 87 or 88 of approximately 0.006 inches. The angled side surfaces may
each be at an angle 0,
that may be different for various configurations, but in the first embodiment,
angled side surfaces 81,
82, 83, and 84 may be oriented such that the angle 0 is a 45 degree angle,
which, when resolved
geometrically, would result in the width of the plateau surfaces 80 being
0.008 inches. Since the
dimensions of the energy directors 79 may not necessarily be very large with
respect to the material
thicknesses being welded, the amount of deformation, discussed earlier, may
similarly not be very
large, and thus does not pose an issue as to tearing of the material of the
work pieces, or even
necessarily, issues relating to plastic deformation.
The sonotrode 50 may have corresponding energy directors, as seen in Figures
21A-21E, and
may similarly include plateau surfaces 60, as well as side surfaces 61, 62,
63, and 64. The improved
sonotrode 50 and anvil 70 may be constructed to have engagement therebetween
of energy directors
comprising a greater surface area of contact between corresponding plateau
surfaces and valleys, than
the traditional flat surfaced sonotrode contacting a flat surfaced anvil. This
increased surface area of
contact, which may be seen from the engagement of the sonotrode and anvil with
the work-pieces in
Figure 22 to cause minor elastic deformation prior to application of
ultrasonic vibrations, results in
more durable ultrasonic welding of two work pieces.
CA 02831272 2013-10-24
In one embodiment of welding being accomplished between the sonotrode and
anvil of the
present invention, alignment of the anvil and sonotrode, which is critical in
each case, consists of
having the energy director grids aligned so that the plateau surfaces of the
sonotrode directly butt
against plateau surfaces of the anvil (Figure 22B). This focuses the vibration
energy into a select grid
pattern, so that when work pieces are inserted between the sonotrode and anvil
(Figure 22A),
ultrasonic welding is achieved more rapidly and efficiently across the entire
weld. The butt-surface
alignment method is favorably used on thicker work pieces and thinner non-foil
applications.
In a second embodiment of welding according to the present invention, which is
advantageous
for thinner work pieces, dramatically improved weld durability is achieved by
utilizing alignment
between the energy director grids whereby the side surfaces of the sonotrode
plateaus interlock with
the side surfaces of the anvil plateaus (Figure 22D) in a repeating 3-
dimensional pattern, which may
include minor elastic deformation of the work pieces. When the work pieces are
inserted between the
sonotrode and anvil (Figure 22C), a three-dimensional weld results. The three-
dimensional weld
exhibits significantly improved durability over that of conventional
ultrasonic welds. Depending on ,
the length of the plateau surface utilized on both the anvil and sonotrode,
the surface area of contact
may be greater or less than the surface area of contact for flat engagement
surfaces of the prior art
welding machines. Even where the surface area of contact is somewhat less than
that of the prior art
flat engagement surfaces, increased durability of the weld results. However,
where a relatively small
plateau surface is used, perhaps being somewhat smaller than the one
illustrated in Figures 20 and
22D, the surface area of contact would be significantly larger, and may
therefore serve to further
reduce the weld times and may also serve to further improve the weld
quality/durability. The limiting
case would be where the length of the plateau approaches zero, so that there
would essentially be
interlocking pyramid shapes, and for the sides being at a 45 degree slope, the
result would be an
26
CA 02831272 2013-10-24
increase in surface area of contact of approximately 41.4 percent (The
mathematical formula for the
surface area of a pyramid being 1/2 x Perimeter x [Side Length] x [Base
Area]). Another means of
describing and/or visualizing the energy director grids of the present
invention, as seen in Figures 19-
20 and 21E, is as a pyramid frustum.
Since the alignment of the anvil and sonotrode in the interlocking alignment
method is crucial
for achieving the results offered herein, the horn 50E may preferably be
designed to include a
peripheral flange 65 at roughly the mid-plane of the horn. The flange 65 may
permit mounting of the
horn in closer proximity to the contact surface 56, rather than relying solely
upon the mounting
connection with the booster, or booster and converter. The need for this type
of flanged horn for
help with alignment is very pronounced for welding of very thin materials.
Figure 24 illustrates the usage of a sonotrode 50B and anvil 70B utilizing the
energy directors
of the present invention, to create an ultrasonic weld that does not follow a
straight-line to create a
linear weld in the form of an elongated weld having a rectangular-shaped
periphery, and alternatively
creates complex, nonlinear weld geometry upon a package to seal the package.
Figure 25 shows anvil
70D, which is capable of being used in the formation of yet another complex
curved weld. These non-
linear anvil/sonotrode combinations may be utilized to weld materials having a
complex irregularly-
shaped periphery, rather than the simple linear weld that is typically used,
such as for a package of
potato chips available at most vending machines. Use of these anvil/horn
energy director grid
combinations also allows for welding of materials to produce durable 3-
dimensional geometries.
Lastly, Figure FIG. 26 shows an alternative "dual lane" horn 50C, having a
first lane 50Ci
and a second lane 50Cii. The dual lane horn 50C accomplishes ultrasonic
welding according to
the present invention, and also accommodates a blade, which may cut through
the center of the
27
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welded materials along the weld line, after welding is completed, with the
blade being able to
bottom-out in the valley between the lanes.
The examples and descriptions provided merely illustrate a preferred
embodiment of the
present invention. Those skilled in the art and having the benefit of the
present disclosure will
appreciate that further embodiments may be implemented with various changes
within the scope
of the present invention. Other modifications, substitutions, omissions and
changes may be made
in the design, size, materials used or proportions, operating conditions,
assembly sequence, or
arrangement or positioning of elements and members of the preferred embodiment
without
departing from the spirit of this invention.
28
