U.S. patent application number 13/892787 was filed with the patent office on 2014-01-23 for packaging machine.
The applicant listed for this patent is Kenneth A. Javor PE, R. Stephen Langer, Rex A. Plageman, James A. Simmons, JR.. Invention is credited to Kenneth A. Javor PE, R. Stephen Langer, Rex A. Plageman, James A. Simmons, JR..
Application Number | 20140020330 13/892787 |
Document ID | / |
Family ID | 49945381 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140020330 |
Kind Code |
A1 |
Simmons, JR.; James A. ; et
al. |
January 23, 2014 |
PACKAGING MACHINE
Abstract
A packaging machine including a supply of film for wrapping a
package and a hot plate for heat fusing the film of a wrapped
package. Power to the heating element is only delivered to the
element during a heating cycle, thus conserving electrical power. A
photo eye senses the package and a control circuit energizes the
heating element the element reaches a desired heating temperature
in 2 to 4 seconds. The frame of the machine includes a lower base
member to which an upper base plate, preferably formed from a
continuous sheet, is rigidly attached. The upper plate includes a
support surface for the hot plate, a vertical wall to which the
photo eye is attached that is interconnected with the support
surface by a curved transition surface. The upper base plate also
includes a lateral, rearwardly extending plate portion which
defines at least a portion of a hardware enclosure.
Inventors: |
Simmons, JR.; James A.;
(Painesville, OH) ; Plageman; Rex A.; (Medina,
OH) ; Javor PE; Kenneth A.; (Concord Township,
OH) ; Langer; R. Stephen; (Auburn Township,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Simmons, JR.; James A.
Plageman; Rex A.
Javor PE; Kenneth A.
Langer; R. Stephen |
Painesville
Medina
Concord Township
Auburn Township |
OH
OH
OH
OH |
US
US
US
US |
|
|
Family ID: |
49945381 |
Appl. No.: |
13/892787 |
Filed: |
May 13, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13382347 |
Jan 5, 2012 |
|
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PCT/US10/41368 |
Jul 8, 2010 |
|
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13892787 |
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61223761 |
Jul 8, 2009 |
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Current U.S.
Class: |
53/76 |
Current CPC
Class: |
B29C 66/849 20130101;
B65B 57/02 20130101; B29C 66/91212 20130101; B65B 51/10 20130101;
B29C 66/861 20130101; B65B 2051/105 20130101; B29C 66/91231
20130101; B29C 65/18 20130101; B29C 66/961 20130101; B29C 66/949
20130101; B29C 66/91655 20130101; B29C 66/962 20130101; B29C
66/91213 20130101; B29C 66/431 20130101; B29C 66/8122 20130101;
B29C 65/30 20130101; B29C 66/81811 20130101; B29C 66/8746 20130101;
B65B 51/148 20130101; B29C 66/91421 20130101; B29C 66/91651
20130101; B29C 66/73921 20130101; B29C 66/8167 20130101; B29C
66/872 20130101; B29C 66/944 20130101; B29C 66/8122 20130101; B29K
2907/04 20130101 |
Class at
Publication: |
53/76 |
International
Class: |
B65B 57/02 20060101
B65B057/02; B65B 51/14 20060101 B65B051/14 |
Claims
1. A packaging machine for wrapping a package with a stretchable
film, the packaging machine having a frame defining a wrapping
surface, a supply of wrapping film accessible by an operator, a
means for severing a length of film used to wrap a package from the
supply and a hot plate including a heating element for fusing at
least a portion of the film that is wrapped around the package,
said packaging machine comprising a package sensor for sensing the
presence of a package to be sealed, said sensor forming part of a
heating circuit for said heating element that applies power to said
heating element when a package is sensed, said sensor comprising a
photo eye assembly arranged such that it senses a package to be
sealed as it is placed on said hot plate.
2. The apparatus of claim 1 wherein said heating element is
energized for as long as a package to be sealed is sensed by said
photo eye assembly.
3. The apparatus of claim 1 further including a temperature
response device associated with said heating element for
deenergizing said heating element if a predetermined operating
temperature is exceeded.
4. The apparatus of claim 1 further comprising a temperature
controller which modulates power to said heating element to
maintain said heating element at a predetermined temperature.
5. The apparatus of claim 4 further comprising a feedback component
which senses temperature of said heating element and communicates
with said temperature controller.
6. The apparatus of claim 5 wherein said feedback component
comprises a thermistor.
7. The apparatus of claim 3 wherein said temperature responsive
device is a thermostat.
8. The apparatus of claim 1 further comprising an interval timer
for controlling a maximum time that said heating element can be
energized.
9. The apparatus of claim 1 wherein said frame comprises: a) a
lower base member having integrally formed side plates and
laterally extending tabs defining a mounting location for a cut-off
rod and at least one upturned mounting flange; b) an upper base
plate defining a substantially horizontal support surface for said
hot plate and a vertical wall interconnected with said support
surface by a curved transition portion and further including a
substantially laterally extending enclosure portion for defining a
portion of a hardware enclosure located between the side plates of
said lower base member when said upper base plate is mounted to
said lower base member; and c) said upper base plate further
including at least one downwardly depending flange that is
engageable with said upturned flange of said lower base member.
10. A packaging machine for wrapping a package with a stretchable
film, the packaging machine having a frame defining a wrapping
surface, a supply of wrapping film accessible by an operator, a
means for severing a length of film used to wrap a package from the
supply and a hot plate including a heating element for fusing at
least a portion of the film that is wrapped around the package,
said packaging machine comprising: a) a lower base member having
integrally formed side plates and laterally extending tabs defining
a mounting location for a cut-off rod and at least one upturned
mounting flange; b) an upper base plate defining a substantially
horizontal support surface for said hot plate and a vertical wall
interconnected with said support surface by a curved transition
portion and further including a substantially laterally extending
enclosure portion for defining a portion of a hardware enclosure
located between the side plates of said lower base member when said
upper base plate is mounted to said lower base member; and c) said
upper base plate further including at least one downwardly
depending flange that is engageable with said upturned flange of
said lower base member.
11. The apparatus of claim 10 further comprising a vertical plate
member for joining said enclosure portion of said upper base plate
with said lower base member.
12. The apparatus of claim 10 wherein said vertical wall portion
mounts said photo eye assembly.
13. The apparatus of claim 10 further comprising a bridge plate
pivotally mounted between said side plates of said lower base
member.
14. The apparatus of claim 5 wherein said feedback component
comprises a thermocouple.
15. The apparatus of claim 10 wherein said lower base member and
said upper base plate are formed from a substantially continuous
metal sheet.
16. A packaging machine for wrapping a package with a stretchable
film, comprising: a) a supply of wrapping film accessible by an
operator and a frame defining a wrapping surface; b) a heated rod
for severing said film; c) said frame defined by a lower base
member and an upper base plate, said base member and upper plate
formed from a continuous sheet material; d) a hot plate for fusing
at least a portion of the film that is wrapped around a package; e)
an optical sensor for sensing the presence of a package to be
sealed on said hot plate, said sensor forming part of a heating
circuit for communicating power to said hot plate when a package is
sensed.
17. The packaging machine of claim 16 wherein said optical sensor
is a photo eye assembly.
18. The packaging machine of claim 17 wherein said upper base plate
defines a support surface for said hot plate, a substantially
vertical portion to which said photo eye assembly is mounted and a
lateral portion at least partially defining an enclosure.
Description
RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 13/382,347, filed Jan. 5, 2012, which claims
the benefit of International Patent Application PCT/US2010/041368,
filed Jul. 8, 2010, which claims the benefit of 61/223,761, filed
Jul. 8, 2009, the disclosure of which is entirely incorporated
herein by reference.
TECHNICAL FIELD
[0002] The present invention relates generally to packaging
systems, and, in particular, to a new and improved package wrapping
machine.
BACKGROUND ART
[0003] Packaging machines of the type that are used to hand-wrap
packages with a thin, often clear film, are often used in
supermarkets to wrap meat, cheese, etc. In a typical machine, a
foam tray on which the meat or cheese is placed is hand-wrapped
with a length of stretchable film that is dispensed from a roll on
the wrapping machine. Once wrapped, the film is severed and the
edges of the sheet are folded and tucked on the underside of the
package. Heat is then used to fuse the film, thus sealing the
package. In a typical machine, a hot plate surface is provided
which is heated to a predetermined temperature that is related to
the temperature needed to cause melting or fusion of the film used
to wrap the package.
DISCLOSURE OF INVENTION
[0004] The present invention provides a new and improved packaging
machine of the type that is used to hand-wrap a package with a
stretchable film. The present invention provides a supply of film
for wrapping a package, a means for severing a length of the film
and a hot plate surface for effecting fusion and sealing of the
film that is wrapped around the package.
[0005] In accordance with a feature of the invention, the presence
of a package to be sealed is sensed when a package is placed on a
hot plate mechanism and/or when the hot plate mechanism is
depressed by the operator. The sensing of a package triggers a
control circuit which energizes a heating element forming part of
the hot plate mechanism and which is arranged to reach a
predetermined operating temperature in less than ten seconds,
preferably in 2 to 4 seconds.
[0006] According to another feature of the invention, the heating
element is only energized for a predetermined interval of time
whenever a package to be sealed is set on it. As a result,
substantial electrical power is conserved since the heating element
is only energized when a package to be sealed is present and only
for a predetermined length of time.
[0007] In the preferred and illustrated embodiment, a hot plate
subassembly is provided that includes a heated platform that is
pivotally attached to a base by a lever arm. In the illustrated
embodiment, a biasing spring urges the heated platform to a raised
position. A position sensor, i.e., a micro-switch, changes state
when the platform moves from its raised position to a package
sealing position.
[0008] The change in state detected by the micro-switch activates a
timer circuit that energizes a heating element forming part of the
hot plate platform in order to provide heat for sealing/fusing the
packaging film.
[0009] According to a preferred embodiment, the length of time
during which the heating element is energized, is determined by an
interval timer having a predetermined time-out interval and which
is also connected to a temperature sensor. In the illustrated
embodiment, a time-out interval is controlled by an external
resistor (which may be selectable by the operator), and the
thermistor that monitors the temperature of the heating
element.
[0010] When a package to be sealed is placed on the platform,
downward movement of the platform causes the micro-switch to change
state and apply power to the hot plate interval timer. If the
heating element does not exceed a predetermined temperature during
the sealing cycle, the heating element will be energized for the
full cycle time determined by the selected resistance. However, if
the desired temperature is reached prior to the end of the sealing
cycle, the thermistor (which monitors the temperature of the
heating element) will cause the timer to immediately time-out and
interrupt power to the heating element.
[0011] According to another feature of the invention, a separate
interval timer is used to activate a light indicator (or other
signaling device, such as a buzzer) in order to provide a visual
means to an operator that the machine is in a heat sealing cycle.
With this arrangement, the indicator light remains illuminated for
the full sealing time, even though power to the heating element may
have been interrupted because it reached its maximum operating
temperature. With this arrangement, the package being sealed will
not be inadvertently removed from the platform prior to full
sealing of the packaging film.
[0012] According to a further feature of the invention, the hot
plate subassembly is pivotally attached to a sub base which, in
turn, is fixed to a machine base. An axle rotatably supported by
flange bushings in the lever arm are secured to upturned flanges
formed in the sub base.
[0013] According to another feature of the invention, the sealing
times are selectable by the operator and in the illustrated
embodiment are provided by a multi-positioned switch which connects
selected resistors to appropriate terminals on the interval timers.
The selected resistors determine the amount of time a given timer
will connect power to its associated device.
[0014] According to another embodiment of the invention, a
packaging machine of the type for wrapping packages with a
stretchable film is disclosed that has a frame, a supply of
wrapping film, a film severing device and a hot plate having a
heating element for fusing at least a portion of the film that is
wrapped around a package. The alternate embodiment of the machine
includes a non-contact or proximity sensor forming part of a
heating circuit for the heating element that applies power to the
heating element when a package is sensed. In the preferred and
illustrated alternate embodiment, the sensor comprises a photo eye
assembly that is arranged such that it senses the package to be
sealed as it is placed on the hot plate. According to a preferred
feature of this embodiment, the heating element is energized for as
long as a package to be sealed is sensed by the photo eye
assembly.
[0015] According to another feature of this embodiment, a
temperature responsive device associated with the heating element
is operative to deenergize the heating element if a predetermined
operating temperature is exceeded. The alternate embodiment
preferably includes a temperature controller which is capable of
modulating power to the heating element to maintain the heating
element at a predetermined temperature rather than fully
deenergizing the heating element when a preselected temperature is
reached, as is the case with the first embodiment. According to a
further feature of the preferred embodiment, a feedback component
such as a thermistor or thermocouple is used to sense temperature
of the heating element and this temperature information is
communicated to the temperature controller which, in turn, may
modulate power to the heating element in accordance with the
temperature information received from the feedback component. In
the illustrated alternate embodiment, an interval timer is also
used in order to control the maximum time that the heating element
can be energized when a heating cycle is initiated upon sensing of
a package to be sealed on the hot plate.
[0016] In accordance with the alternative embodiment, a packaging
machine frame is provided which includes a lower base member having
integrally formed side plates and laterally extending tabs that
define a mounting location for a cut-off rod. The lower base member
also includes at least one upturned mounting flange.
[0017] The frame also includes an upper base plate that defines a
substantially horizontal support surface for the hot plate and a
vertical wall that is interconnected with the support surface by a
curved transition portion. The upper base plate further includes a
substantially laterally extending enclosure portion for defining a
portion of a hardware enclosure located between the side plates of
the lower base member when the upper base plate is mounted to the
lower base member. The upper base plate further includes at least
one downwardly depending flange that is engageable with the
upturned flange defined by the lower base member.
[0018] The disclosed frame construction allows for easy maintenance
and cleaning of the packaging machine and the construction is
adaptable to a wide variety of packaging machines of the type to
which the invention pertains and may be incorporated, for example,
in the packaging machine of the first embodiment.
[0019] According to a feature of the alternate embodiment, the
photo eye assembly is mounted and carried by the vertical wall
portion of the upper base plate. According to another feature of
this embodiment, a vertical plate member is used to join the
enclosure portion of the upper base plate with the lower base
member.
[0020] Additional features of the invention will become apparent
and a fuller understanding obtained by reading the following
detailed description made in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1A is an isometric view of a wrapping machine
constructed in accordance with a preferred embodiment of the
invention;
[0022] FIG. 1B is an exploded view of the machine shown in FIG.
1A;
[0023] FIG. 2 is a sectional view through the center of the machine
shown in FIG. 1A;
[0024] FIG. 3 is a perspective view of a hot plate mechanism
constructed in accordance with the preferred embodiment of the
invention;
[0025] FIG. 4 is an exploded view of the hot plate mechanism shown
in FIG. 3;
[0026] FIG. 5 is a block diagram of the control system for a hot
plate heater;
[0027] FIG. 6 is a schematic of a circuit that controls the heating
of the hot plate shown in FIG. 3, as well as a rod for severing the
packaging film from a supply roll;
[0028] FIG. 7A is a block diagram of an alternate control system
for a hot plate heater;
[0029] FIG. 7B is a schematic of an alternate circuit for
controlling the heating of the hot plate shown in FIG. 3;
[0030] FIG. 8 is an isometric view of a wrapping machine
constructed in accordance with another preferred embodiment of the
invention;
[0031] FIG. 9 is a sectional view through the center of the machine
that is shown in FIG. 8 and is similar to the view shown in FIG.
1A;
[0032] FIG. 10A is a block diagram of an alternate control system
for a hot plate heater shown in FIGS. 8 and 9; and
[0033] FIG. 10B is a schematic of the control system shown in block
diagram form in FIG. 10A.
BEST MODE FOR CARRYING OUT THE INVENTION
[0034] FIGS. 1A, 1B illustrate a wrapping machine constructed in
accordance with a preferred embodiment of the invention. As is
known, this type of machine is used to wrap packages with a
stretchable, heat-sensitive film. Once the package is wrapped, heat
is used to fuse the wrapping in order to seal the package. This
type of machine is often used in supermarkets to package produce,
meats, etc.
[0035] The illustrated wrapping machine is considered a tabletop
machine. It should be understood, however, that the principles of
this invention, to be described, are equally applicable to floor
and self-standing wrapping machines.
[0036] As seen best in FIG. 1B, the machine includes a frame
indicated generally by the reference character 10 that comprises a
pair of side plates 14, 16 and base 18. In the preferred
embodiment, the frame is made from aluminum and is formed from a
single sheet of material formed into the U-shape shown in FIG.
1B.
[0037] A roll of stretchable packaging film 20 is supported for
rotation by a pair of supports indicated generally by the reference
characters 21, 22 (see FIG. 1A). In the illustrated embodiment,
each support comprises a pair of support blocks 24, 26 that are
clamped together by a pair of threaded studs or screws 28 and
associated wing fasteners 30. The roll 20 itself is mounted to a
reusable roll support that comprises end pieces or flanges 34 and
an axle 36. The ends of the axle 36 are removably captured between
the support blocks 24, 26. When the supply of wrapping material is
exhausted, the roll support is removed from the machine by removing
the wing nuts 30 to enable the upper support block 24 to be
removed. This releases the ends of the axle 36 and allows the
operator to install a fresh supply of wrapping material or
film.
[0038] A pivotally mounted plate or bridge 40 defines a wrapping
surface 40a upon which a package is wrapped with film from the
supply 20. The bridge 40 includes a pair of downwardly depending
end flanges 40b which overlie the outer, upper edge surfaces of the
side plates 14, 16 and a rigidizing back flange 40c. Gaps 41d
provide clearance for the upper edge of the side plates 14, 16.
This construction provides support for the bridge when rotated into
its horizontal position shown in FIG. 1A. The bridge 40 can be
pivoted upwardly about a pivot 42 to expose the inside of the
machine including its electrical box 46. As seen best in FIG. 2, a
cover plate 46a encloses the electrical components housed within
the box 46. The cover 46a covers a compartment 48 which houses
circuitry and other components necessary for the operation of the
machine.
[0039] The wrapping material is dispensed from the roll 20 along
the path P. The material is guided by the cover 46a and emerges
through an opening defined between the front edge 41 of the bridge
40 and a retainer rod 50. In the preferred and illustrated
embodiment, the retainer rod 50 is covered with a coating, i.e.,
vinyl, to which the wrapping material releasably adheres so that
the end of the material is maintained and positioned for easy
grasping by the operator. The cover 40 is pivoted upwardly (as
viewed in FIG. 2) to expose the feed path and facilitate feeding of
the wrapping material.
[0040] The package to be wrapped is placed on the bridge 40 and a
suitable length of film material is pulled from the supply by the
operator. The operator then hand wraps the material around the
package.
[0041] When the wrapping material fully encompasses the package,
the portion of the wrapping surrounding the package is severed from
the rest of the web by preferably contacting a heated rod 58. Since
the material is heat sensitive, contact with the heated rod causes
severance of the material.
[0042] In general, once the wrapped package is severed from the
rest of the web, the wrapping is gathered, tucked or folded
underneath the package. According to the invention, the side of the
package with the gathered/folded material is placed upon a hot
plate subassembly indicated generally by the reference character 60
which includes a heated hot plate 64. The heat from the hot plate
64 causes fusion of the material and, hence, seals the package.
[0043] According to the invention, the hot plate 64 is not
energized or heated until a package is placed on its sealing
surface 64a. According to the preferred embodiment and, as best
seen in FIGS. 2 and 3, the hot plate or heated platform 64 is
pivotally attached to the base 18 by a lever arm assembly 66 which
includes a lever arm 66a and a sub-base 66b. The lever arm 66a is
best shown in FIG. 4 and includes a pair of side plates 67a, a rear
plate 67b, a top plate 67c and a support plate 67d to which the hot
plate 64 is attached by a plurality of fasteners 69. The lever arm
66a mounts an axle 68 which, as seen in FIG. 3, includes ends that
extend beyond the side plates 67a. The sub-base 66b includes a
plurality of mounting holes 65 by which the sub-base 66b is rigidly
attached to the base 18. The sub-base 66b includes a pair of
parallel, upturned flanges 71, which include apertures 71a, by
which fasteners 71b are used to secure ends of the axle 68 to the
flanges 71 and which thus pivotally support the lever arm 66a. The
axle 68 is preferably supported by flanged bushings 73.
[0044] In a preferred and illustrated embodiment, and as best seen
in FIGS. 1A and 2, an indicator light 75 (i.e., LED) is mounted to
the top plate 67c of the lever arm 66a. In the preferred
embodiment, the LED is energized to indicate to an operator that
the machine is in a heating/sealing cycle.
[0045] As seen in FIGS. 2 and 3, the hot plate subassembly 60
includes a micro-switch 70 that is secured to the back plate 67b of
the lever arm 66a and which includes an actuating plunger 72. In
the illustrated embodiment, when the hot plate subassembly 60 is in
its upper position as viewed in FIG. 2, the plunger 72 is depressed
by contact with the sub-base 66b. When a package is placed on the
hot plate surface 64a, either the pressure of the operator or the
weight of the package or both causes the hot plate to move
downwardly as viewed in FIG. 2, thereby causing upward movement in
the opposite end of the lever arm 66a which, in turn, causes the
micro-switch plunger 72 to be released allowing it to move
outwardly (downwardly as viewed in FIG. 2). In the preferred
embodiment, the hot plate subassembly is biased towards its upper
position shown in FIG. 2 by a tension spring 76 that is captured by
a lug 78 forming part of the lever arm 66a and a lug 79 secured to
the sub-base 66b (shown best in FIGS. 3 and 4).
[0046] As is known, the plunger 72 is coupled to normally closed
(N/C) and normally opened (N/O) contacts within the micro-switch 70
which open and close, depending on the position of the plunger 72.
As will be explained, the micro-switch 70 is used to control the
energization of the indicator light 75 and a heating element
forming part of the hot pate 64. It should be noted here, that the
location of the micro-switch can be varied and, may in fact, be
positioned further upstream from the hot plate 64 should earlier
energization of the hot plate be desired.
[0047] Referring to FIG. 4, the details of the hot plate
construction are illustrated. In addition to what has already been
described, the hot plate 64 includes a base plate 80 which may be
fiberglass, a sheet of insulation 82 and a heating element 84, all
of which are sandwiched together by a pair of longitudinal frame
rails 86 and a pair transverse frame rails 88. In the preferred
embodiment, a temperature monitoring thermistor 89 having
connection wiring 89a is attached (as by taping) to the insulation
sheet 82. In the preferred embodiment, a heat sink pad 91 is
provided to buffer the heat generated by the heating element 84.
The heat sink pad 91 allows the use of a thinner heating element
layer. In the preferred embodiment, the heat sink pad is graphite
and this type of material is available from EGC Enterprises, Inc.,
of Chardon, Ohio. Fasteners, including a plurality of nuts and
washers, are used to maintain the assemblage.
[0048] As seen best in FIG. 4, the base plate 80 is rigidly fixed
to one side of the lever arm 66 by suitable fasteners. The base
plate 80 and insulation sheet 82 include respective access holes
80a, 82a through which wiring W (shown in FIG. 3) for the heating
element 84 are fed.
[0049] According to the invention, the heating element 84 is
capable of reaching a desired operating temperature sufficient to
provide sealing of the package in less than 10 seconds. This is
achieved by utilizing a graphite-based heater and a suitable
control circuit. According to the invention, the micro-switch 70 is
used to sense the presence of a package on the hot plate 64 i.e.
when a package is placed on the hot plate, the resulting downward
movement of the lever arm 66 causes the micro-switch to change
state. The micro-switch forms part of a power circuit for providing
power to the heating element 84 sufficient for it to reach a
desired operating temperature within a very short period of time,
i.e., 2 to 10 seconds. In the preferred and illustrated embodiment,
the heating element 84 is of a rapid, response flexible graphite
foil heater, an example of which is available from EGC Enterprises,
Inc., of Chardon, Ohio.
[0050] The ability for the hot plate to quickly reach the desired
temperature is further achieved by reducing the thermal mass of the
hot plate 64, thus reducing the thermal time constant for the
apparatus. As noted above, the base plate 80 is preferably
constructed of fiberglass which has a relatively low mass. In
addition, the insulation sheet 82 is also of a low mass material.
One such material is sold under the "AEROGELS" brand and is sold by
Aspen Aerogels, Inc. of Northborough, Mass. In addition, the
heating element 84 is selected to have a low mass as well. In the
preferred construction, the relatively low mass of the overall hot
plate 64, coupled with the rapid response time of the preferred
heating element 84, provides a hot plate with a very rapid response
time. In the preferred embodiment, the heater reaches the desired
operating temperature from ambient in 2 to 4 seconds.
[0051] FIG. 5 illustrates a block diagram of the control system for
energizing the hot plate 64. The block 100 represents a source of
power, in this case, AC power. AC power is fed to the micro-switch
or cycle start switch 70 (the details of which will be described
later) and to a pair of interval timers 106a, 106b. In the
preferred and illustrated embodiment, the interval timer 106a is a
relatively low powered timer, (i.e., 1 amp) and is used to control
the energization of the light indicator 75 and/or a signaling
buzzer 75a. The interval timer 106b has the capability of
controlling significant power, (i.e., 30 amps) and is used to
control the energization of the heating element 84.
[0052] As seen in FIG. 5, both timers 106a, 106b are initiated by a
change of state in the cycle start switch 70 (which is mounted to
the lever arm 66a). The length of time that the timers 106a, 106b
apply power to their respective devices is determined by external
resistors. In the preferred embodiment, a multi-position, rotary or
slide switch 114 is used to connect suitable resistances to the
timers 106a, 106b. The resistance selected determines, in part, how
long a given timer will apply power to its associated device. In
the preferred embodiment, the timer 106a energizes the light
indicator 75 (and/or the buzzer 75a) for a length of time totally
determined by the resistance selected. The interval timer 106b,
however, applies power to the hot plate heater 84 as a function of
both the resistor selected and the thermistor 89 that monitors the
temperature of the heating element. In particular, the resistance
selected and connected to the interval timer 106b determines the
maximum time that power will be applied to the heating element.
However, if the thermistor senses that the desired temperature is
reached prior to the time determined by the resistor, the timer
106b will time-out and interrupt power to the heater 84. During
periods of heavy usage, the actual time that power is applied to
the hot plate heater 84 is substantially shorter than the heating
cycle time determined by a given resistor. It should be noted, that
because the indicator light 75 is controlled by an independent
timer, the sealing time, as observed by the operator by virtue of
the indicator light, remains unchanged, even though power to the
hot plate heater may be terminated. As a result, consistent sealing
of packages is assured, as compared to a circuit in which an
indicator light is only illuminated when power to the hot plate 84
is applied.
[0053] FIG. 6 is a schematic for a control circuit for the hot
plate heater. In the illustrated embodiment, the circuit is powered
from a 115 volt AC receptacle. The circuit includes a power switch
200 which, when closed, provides power to the heated rod cutter
element 58 (shown in FIG. 1A), and the micro-switch 70 (also termed
cycle start switch). As seen in FIG. 6, the temperature of the
cutter element 58 is controlled by a conventional circuit carried
on a circuit board 58a, which is supplied by TUTCO Inc. of
Cookeville, Tenn. The switched leg of the AC power is connected to
the cycle switch 70, the hot rod cutter circuit 58a, and one side
of a heat indicating light 75. The micro-switch 70 forming part of
the hot plate platform and seen best in FIG. 3 is represented in
the schematic by the double pole switch 70 termed a cycle start
switch in FIG. 6. It is shown with the normally open (N/O) contacts
closed because when the platform is in the upper position, the
plunger 72 is depressed which opens the normally closed (N/C)
contacts and closes the normally open contacts. When the platform
is moved downwardly by placement of the package on the heating
surface 64a, the state of the switch 70 changes so that the
normally open contacts open and the normally closed contacts close.
The closure of the normally closed contacts causes power to be fed
to pins 21 (+pins) of the interval timers 106a, 106b. This change
in switch position causes activation of the timers 106a, 106b and
causes these timers to apply power to their associated devices,
depending on the external resistance connected to a given timer. In
the case of the interval timer 106a (which controls the activation
of the indicator light 75), a selected external resistance is
applied to its terminals 34, 33, the value of the resistance being
determined by the position of the switch 114.
[0054] In the case of the interval timer 106b (which provides power
to the heating element 84), its time-out is determined by the
external resistance applied to its associated terminals 25, 24. As
seen best in FIG. 6, the actual resistance applied to these
terminals is determined by the position of the switch 114, as well
as the thermistor 89. The time-out of the interval timer 106b can
vary for a given position of the switch 114. The timer interval is
also determined by the temperature of the heating element 84 as
measured by the thermistor 89. As a result, and especially during
heavy usage, the interval of time during which power is applied to
the heating element 84 may be substantially shorter than the actual
sealing cycle time as indicated by the interval timer 106a.
[0055] With the preferred construction, when a package is placed on
the hot plate 64, the resulting downward movement of the hot plate
causes the micro-switch 70 to deactivate which, in turn, causes the
energization of the timers 106a, 106b for a predetermined time
determined by the external resistance selected by the switch 114
and the thermistor 89. As indicated above, the indicator light 75
is energized for a predetermined time determined solely by the
resistance selected by the switch 114. For the interval timer 106b,
the resistance selected by switch 114 determines the maximum time
that the heating element 84 will be energized. If a threshold
temperature is exceeded during the heating cycle, this excess
temperature sensed by the thermistor 89 will cause the timer 106b
to time out and interrupt power to the heating element 84.
[0056] With the present invention, the heater is only energized
when a package is to be sealed. Since the heater is only energized
for a predetermined length of time as determined by the rotary or
slide switch 114 and thermistor 89, leaving the package on the
platform will not cause continuous energization of the heater which
could cause overheating. It should be noted here that the rotary or
slide switch 114 which is used to connect selected external
resistors to the interval timers 106a, 106b, can be replaced by one
or more potentiometers.
[0057] It should also be noted that the present invention
contemplates a sealing machine that does not have an adjustable
sealing time. For this type of machine, fixed resistors may be
connected to the suitable terminals of the interval timers 106a,
106b or, alternately, timers having a fixed time interval may be
used and, thus, eliminate the need for external resistors. It
should also be noted that, in the preferred embodiment, the switch
114 may comprise a three position slide switch available from
Switchcraft Inc., of Chicago, Ill., under part number
502-46313LDRX. The thermistor 89 in the preferred embodiment has a
resistance of 500 K ohms at 25.degree. C.
[0058] FIG. 7A illustrates a block diagram of an alternate control
system for energizing the hot plate 64. The block 100' represents a
source of power, in this case, AC power. AC power is fed to the
micro-switch or cycle start switch 70 and to an off delay timer
106' which is arranged to energize the hot plate heating element 84
for a predetermined interval upon actuation. The communication of
power to the hot plate heater is actually controlled by a
solid-state switch 114'. In order for the solid state switch to
close and provide power to the hot plate heating element 84, it
must receive an ON signal from both the off delay timer 106' and
from a thermostat 118 (which is also connected to the incoming AC
power). In the preferred embodiment the thermostat 118 is attached
and forms an integral part of the heating element 84. The
thermostat 118 senses an overheat condition and opens to interrupt
the signal or power to the solid state switch 114' coming from the
power block 100'. As indicated above, if either the signal from the
thermostat 118 or from the off delay timer 106' is terminated, the
solid-state switch 114' opens to interrupt power to the hot plate
heating element 84.
[0059] FIG. 7B is a schematic for the alternate control circuit for
the hot plate heater. In the illustrated embodiment, the circuit is
powered from a 115 volt AC receptacle. The circuit includes a power
switch 200' which, when closed, provides power to the heated rod
cutter element 58 (shown in FIG. 1A), the solid switch relay 114'
and one leg of the off delay timer 106'. The switched leg of the AC
power is connected to the off delay timer 106', the hot rod cutter
58, one side of a heat indicating light 206, one side of the
thermostat 118 and one side of the heating element 84. The
micro-switch 70 forming part of the hot plate platform and seen
best in FIG. 3 is represented in the schematic by the double pole
switch 70. It is shown with the normally open (N/O) contacts closed
because when the platform is in the upper position, the plunger 72
is depressed which opens the normally closed (N/C) contacts and
closes the normally open contacts. When the platform is moved
downwardly by placement of the package on the heating surface 64a,
the state of the switch 70 changes so that the normally open
contacts open and the normally closed contacts close. The closure
of the normally closed contacts causes power to be fed to pin 9 of
the off delay timer 106' and interrupts power to pin 7. This change
in switch position causes the off delay timer 106' to send a signal
to pin 3 of the solid state relay 114' for a predetermined length
of time as determined by the adjustable potentiometer 210' that is
connected across pins 5 and 6 of the off delay timer 106'. If the
thermostat 118 that forms part of the heating element 84 is closed,
the application of the power signal to pin 4 of the solid state
relay 114' causes power to be applied to the hot plate heater from
pin 1 of the solid state relay 114. When the off delay timer 106'
times out, the interruption of signal to pin 3 of the solid state
relay 114' causes the de-energization of the hot plate heater
64.
[0060] It has been found, that with the disclosed construction and
the use of the thin film graphite-based heater, continuous heating
of the hot plate is not required. It has been found that the
application of power to the heating element results in the heater
reaching a desired temperature within 2 to 10 seconds, preferably
less than 4 seconds. In short, during machine operation power is
applied to the heater for only short intervals of time and, as a
result, significant power savings can be realized as compared to a
package-wrapping machine in which the hot plate is continuously
energized.
[0061] FIGS. 8 and 9 illustrate another preferred embodiment of the
invention. To facilitate the explanation, components and structures
of the alternate embodiment that are the same or similar to the
components and structures shown in FIGS. 1A, 1B and 2 will be given
like reference characters, followed by an apostrophe.
[0062] The packaging machine shown in FIG. 8 includes a frame
indicated generally by the reference character 10'. Referring also
to FIG. 9, the frame 10' comprises a lower base member 220 to which
an upper base plate 224 is rigidly attached. As seen best in FIG.
8, the upper base plate 224 spans the entire width of the lower
base member 220 and includes downturn flanges 224a, 224b which are
secured to associated upturned flanges 220a, 220b (see FIG. 9)
integrally formed in the lower base member 220. As seen best in
FIG. 9, the upper base plate 224 is a continuous plate that
includes a horizontal support surface 230 and a vertical wall 232
joined together by a continuous, arcuate transition 236. From the
vertical wall 236, another horizontally extending plate portion 238
is formed and joins an L-shaped vertical plate 240 (see FIG. 9)
which joins and rigidly attaches a rear downwardly depending flange
238a of the upper base plate to the lower base member 220. With the
disclosed construction, an extremely rigid and cost effective frame
is defined by two formed, sheet metal components. The upper
horizontal plate section 238, as seen in FIG. 9 in cooperation with
the L-shaped vertical plate 240 defines an electrical box 46' which
houses circuitry and other components necessary for the operation
of the machine (not shown). With the disclosed arrangement, the
construction of the packaging machine is greatly simplified and
many individual frame components used in the FIG. 1 embodiment are
eliminated.
[0063] Like the embodiment shown in FIG. 1, the FIG. 8 embodiment
includes a pivotally mounted plate or bridge 40' that defines a
wrapping surface 40a', upon which a package is wrapped with film
from a supply 20'. Side plates 14' integrally formed in the lower
base member 220 include integrally formed flanges 242 that mount a
heated rod cutter element 58' and a retainer rod 50'. The bridge
plate 40'is pivotable about an axle or pivot 42' to expose the
inside of the machine and to facilitate feeding of the film from
the supply roll 20'. The feed path for the film is indicated by the
reference character P'. As seen best in FIG. 9, the forward end of
the bridge plate 40' defines a curved rigidizing edge 40c'. As seen
best in FIG. 8, the bridge 40' includes a pair of downwardly
depending end flanges 40b' which overlie the outer, upper edge
surfaces of the side plates 14'. This construction provides support
for the bridge 40' when rotated into its horizontal position. The
illustrated arrangement is substantially similar to the arrangement
shown in connection with the bridge 40 shown in FIG. 1A. It should
also be noted that the curved forward edge 40c' of the alternate
bridge plate 40' provides a construction by which the bridge plate
40' can be pivotally mounted so that it opens about a pivot defined
by the curved edge 40c' and an associated pivot rod (not shown).
The engagement of the upper edges of the side plates 14' with the
end flanges 40b' maintains a bridge plate 40' in the horizontal
position shown in FIG. 9.
[0064] The horizontal plate portion 230 of the upper base plate 224
includes a heated hot plate 64' which may be similar or
substantially the same as the hot plate 64 shown in FIG. 1A.
However, the hot plate 64' is rigidly attached to the fixed, upper
base plate 224 and is not pivotally movable. In the embodiment
shown in FIG. 9, a photo eye 250 is used to detect the presence or
absence of a package and forms part of the heating circuit for the
hot plate 64'. When a package is detected by the photo eye, 250,the
heating cycle is initiated in order to heat the hot plate 64' and
thereby fuse the package film.
[0065] It should be noted that the sealing functioning performed by
the packaging machine embodiment shown in FIGS. 9 and 10 is similar
to sealing function performed by the packaging machine embodiment
shown in FIG. 1A. However, the pivot assembly and associated
plunger switch forming part of the packaging machine shown in FIG.
1A are eliminated in the packaging machine shown in FIG. 8.
[0066] The film supply 20' is supported for rotation by a pair of
supports indicated generally by the reference characters 21', 22',
which may be the same or similar to the supports 21, 22 shown in
FIGS. 1A, 1B.
[0067] The packaging machine embodiment shown in FIGS. 9 and 10
requires less individual components than the packaging machine
shown in FIG. 1A. Moreover, the frame comprises only two major
components, i.e., lower base member 220 and upper base plate 224.
Each base member is formed from a single sheet metal and once
assembled, form a rigid frame which as seen best in FIG. 9, can be
easily cleaned and maintained. The elimination of the pivoting
platform and the use of a continuous plate member that forms both
the support surface for the hot plate and the cover for the
electrical enclosure substantially reduces costs while providing
surfaces that can be easily cleaned and maintained. The alternate
embodiment substantially reduces the number of moving parts such as
the platform assembly shown in FIG. 1A, thus reducing or
eliminating a maintenance issue. In the preferred and illustrated
embodiment, the lower base member and the upper base plate are
formed from a continuous sheet of material, such as steel or
aluminum sheet metal.
[0068] FIG. 10A illustrates a block diagram of an alternate control
system for energizing the hot plate 64' shown in FIGS. 8 and 9. The
block 100' represents a source of power, in this case AC power.
Those skilled in the art will recognize that entire circuits may be
DC powered. AC power is fed to the cycle start switch 250 which in
this alternate embodiment preferably comprises a photo eye
assembly. A photo eye assembly suitable for this application is
available from Banner Engineering of Minneapolis, Minn. under the
Part No. QSI18VP6D.
[0069] When the cycle start switch 250 closes, power is
communicated concurrently to an interval timer 106'' and a
thermostat 118'. The interval timer 106'' doses for a predetermined
interval of time after energization, i.e., 5 seconds. As indicated
above, power is also communicated to the thermostat 118' which, if
closed, communicates power to a temperature controller 260. In the
preferred embodiment, the thermostat 118' is located within the hot
plate assembly 64' and opens to interrupt power if the hot plate
temperature exceeds a predetermined value.
[0070] If the thermostat 118' is closed, power is communicated to
the temperature controller 260, which in the preferred and
illustrated embodiment is a proportional-integral-derivative (PID)
controller. The controller 260 directs power to the hot plate 64'
via the interval timer 106'. The temperature of the hot plate 64'
is monitored by a feedback component such as a thermistor or
thermocouple 266. At the start of the heat cycle, the temperature
controller 260 communicates a substantial current to the hot plate
64' in order to quickly heat the hot plate 64' to a desired sealing
temperature. When the preselected temperature is reached and
communicated to the temperature controller 260 via the feedback
component 266, the temperature controller 260 modulates the power
being fed to the hot plate in order to maintain the selected
temperature.
[0071] In the preferred embodiment shown in FIG. 10A, when the
photo eye 250 detects a package being placed on the hot plate 64',
the temperature controller feeds sufficient power to the hot plate
in order to heat it to a desired temperature within a few seconds,
i.e., three. Once this temperature is reached, the temperature
controller modulates power to the hot plate 64' to maintain it at
the desired temperature until removal of the sealed package is
detected by the photo eye 250. If a package is inadvertently left
on the hot plate platform 64' beyond a predetermined time, i.e.,
five seconds, the interval timer 106'' opens to interrupt power to
the hot plate 64'. In the preferred embodiment, a heat cycle cannot
be reinitiated until removal of the package from the hot plate 64'
is detected by the photo eye assembly 250.
[0072] FIG. 10B is a schematic of the alternate control
system/circuit for the hot plate heater that is shown in block form
in FIG. 10A. The circuit is powered from 115 volt AC receptacle
264. The circuit includes a power switch 200'' which, when closed,
provides power to the heated rod cutter element 58' and a DC power
supply 270. The closure of the AC power switch 200' also
communicates power to one leg or side of a solid state switch or
relay 268 and one power leg of the temperature controller 260. The
photo eye assembly 250 is arranged such that when placement of a
package on the hot plate 64' is detected, the photo eye assembly
250 causes power to be communicated to the other power leg or side
of the solid state switch 268 causing its closure and the
communication of DC power to the other leg of the temperature
controller 260 and to a contact on the solid state switch 268.
Power is thus communicated to the hot plate 64' provided that the
appropriate contacts of the interval timer 106'' are closed and the
thermostat 118' is closed.
[0073] In the illustrated embodiment, the hot rod cutter 58' is
powered by the same circuit as that shown in FIG. 6 and as used in
the embodiment of the packaging machine shown in FIG. 1A.
[0074] As the hot plate approaches the set point temperature, the
PID controller 260 begins to modulate power in an effort to reduce
the rate of heating. As the set point is attained, the PID
temperature controller 260 will modulate power to maintain this
temperature until the system is deactivated. A potentiometer 276
forms part of the circuit and is used to modify the resistive
feedback to the temperature controller 260 and provides a means by
which different temperature set points can be set for the hot plate
64'.
[0075] With the disclosed circuit and package detecting
methodology, a robust control circuit is provided for providing an
"instant on" function for the packaging machine. It is believed
that the arrangement which uses a photo eye assembly 250 for
package detection causes quicker energization of the hot plate when
a package is to be sealed. With the FIG. 1A embodiment, the package
must be placed on the platform and the platform must pivot
downwardly in order to actuate the plunger switch 70. In this
alternate embodiment, as the package is moved from the wrapping
platform 40' to the hot plate 64', its movement is detected and the
heating cycle is immediately initiated even before the package to
be sealed reaches the hot plate 64'. This causes the hot plate to
reach its sealing temperature quicker as compared to the FIG. 1A
embodiment.
[0076] It is believed that the alternate control system/circuit,
reduces costs while improving functionality. It is believed that
the circuit can be further simplified by eliminating what some
would consider to be redundant components. For example, the
temperature controller 260 can be used without the interval timer
106''. The feedback component 266 can be relied upon to control the
temperature controller in order to cause it to terminate power to
the hot plate when a temperature above a predetermined threshold is
detected by the feedback component 266. It is believed that the
thermostat 118' may also be eliminated if the temperature
controller is also used to detect an over temperature condition in
the hot plate 64' as measured by the feedback component 266.
[0077] In the disclosed embodiment, the photo eye assembly 250
works in conjunction with a DC power supply and controls the
operation of the DC powered control components. The disclosed photo
eye assembly operates on a supply voltage of from 10 to 30 volts
DC. There are photo eye assemblies that operate with a supply
voltage of 110 volts AC. If this type of photo eye assembly is
employed, the DC power supply 270 could be eliminated. In fact, a
photo assembly of the type that operates on a supply voltage of 110
AC can be directly substituted for the plunger switch 70 of the
first embodiment (see FIGS. 3 and 6).
[0078] A suitable temperature controller is available from Crydom
Inc. under Part No. MCTC2425JLA-E. A suitable solid state
switch/relay is available from Crydom Inc. of San Diego, Calif.
under Part No. EL240A20-US. A suitable interval timer is available
from Precision Timer, a division of Prime Technology of North
Branford, Conn. under part No. 843E-150. A suitable DC power supply
is available from CUI Inc. of Tualatin, Oreg. under Part No.
VSK-S5-24UA-T.
[0079] The invention has been described as forming part of a
hand-wrapping machine use in supermarkets. However, the invention
has much wider applicability. For example, it can be used in other
environments such as laundry wrapping environments. It also may be
used as part of automated wrapping machines used in various
industries. Accordingly, the present invention should not be
limited to wrapping machines of the type found in supermarkets.
[0080] Although the invention has been described with a certain
degree of particularity, those skilled in the art can make various
changes to it without departing from the spirit or scope of the
invention as hereinafter claimed.
* * * * *