Note: Descriptions are shown in the official language in which they were submitted.
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STA 76031 PC -l-
HEAT SEALING APPARATUS
l~nNlCAL FIELD
This invention relates to apparatus for
thermally bonding indicia to fabric and more particular-
ly to a heat sealing machine of a type used for applyingletters and logos to garments.
BA~,r~O~JNL~ ART
Conventional heat sealing machines are of two
general types. The two types include a clam shell type
and a swing away type. Both machines include upper and
lower platens which are movable relative to one another
and thereby registerable in a closed position. A heat
source is included in one of the platens. Thermally
bonding indicia such as letters, numbers and identifying
logos are applied to a fabric such as a T-shirt,
sweatshirt or other garment by placing the indicia on
the fabric between the platens, applying pressure to
force the platens toward one another and at the same
time applying heat sufficient to cause the thermally
bonding indicia to stick to the fabric. After an
appropriate time interval, the platens are separated
and the fabric with indicia attached is removed.
These two types of machines can further be
categorized as manual, semi automatic and automatic
machines. All machines require an operator. The manual
machines require the operator to control the pressure
between the platens, the temperature and the time during
which the pressure and temperature is applied to the
indicia and fabric. Semi automatic machines require the
platens to be registered manually but release the
platens automatically after the timing cycle. Automatic
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machines require compressed air or a motor to supply the
force required to move the platens into a registration
position and apply pressure and subsequently separate
the platens after the timing cycle. Pressure between
the platens during registration in these machines is a
function of the force of the operator or other mechani-
cal means used to accomplish registration. No manually
operated or semi automatic machines are known which
include a means to control or regulate the pressure
between the platens. This inability to control the
pressure between the platens doesn't allow the operator
to know that the pressure being applied is correct and
results in duplication when each of the same sets of
letters and fabrics must be set up for bonding for each
application. The application of the same indicia to the
same fabric cannot be duplicated. When incorrect
pressure is applied, as often it is, a less than optimal
bond between the indicia and fabric results.
The time during which the platens are
registered is equally important as is the pressure
applied and also the heat to insure a good bond of the
letters to the garment. On both the manual and semi
automatic machine, the timing cycle is initiated by the
operator and most often the timer is a clock or
wristwatch although other types of timers have been
employed. The inconsistency of having a human operator
initiate the timing cycle gives rise to having different
periods of application of pressure between the platens
to similar letters and fabrics which leads to poor
bonding.
Furthermore, no manually operated or semi
automatic machines are known which simultaneously
control pressure, time and temperature. All of these
variables are dependent upon one another yet no heat
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sealing machines simultaneously control these variables
to provide an efficient application operation.
DISCLOSURE OF THE INVENTION
An object of the present invention is to
provide an improved apparatus for thermally bonding
indicia to fabric which is controllable with respect to
pressure, time and temperature to insure consistent and
reproducible bonding of indicia such as letters and
logos to fabric such as wearing apparel, banners, etc.
The improved apparatus is simple in construction and
simple to use.
In carrying out the above object and other
objects of the invention, the improved apparatus has
relatively movable upper and lower platens with a heat
source in one of the platens for heating it and a
mechanism for urging the platens together and for
varying the pressure between the platens during closure.
The improved apparatus is programmable with respect to
duration of platen closure and temperature of the heated
platen. The apparatus includes a pressure sensor for
measuring the pressure between the platens during
closure. A visual display is provided to indicate the
pressure reading, temperature and duration of platen
closure. The visual display is capable of displaying
any commands or readings in any of several languages.
A programmable controller, operable to control
the time, and temperature, includes a memory so that a
plurality of sets of temperature, pressure, and platen
closure periods can be stored in order to make the
operation of the apparatus very easy when duplication of
application of similar indicia to similar fabric is
required.
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The objects, features, and advantages of the
present invention are readily apparent from the
following detailed description of the best mode for
carrying out the invention when taken in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of an improved
heat sealing machine constructed in accordance with the
present invention;
Figure 2 is a plan view of the heat sealing
machine showing a cantilever arm supporting an upper
platen and illustrating a strain gage thereon the
cantilever arm;
Figure 3 is a sectional elevational view of
the heat sealing machine taken along line 3-3 in Figure
2;
Figure 4 is a front elevational view of the
machine illustrating the construction of the upper
platen shown for heating;
Figure 5 is a sectional view taken along the
line 5-5 in Figure 4 illustrating the positioning of
cal-rods in the heating platen;
Figure 6 is an enlarged sectional view of the
strain gage on the cantilever arm;
Figure 7 is an enlarged sectional view
illustrating an optical switch mounted under the
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STA 76031 PC - 5 -
cantilever arm for sensing closure of the upper platen
against a lower platen;
Figure 8 is an enlarged sectional view taken
along the line 8-8 in Figure 7 illustrating the
operation of the optical switch; and
Figure 9 is a schematic illustration showing
the integrated control features of the machine.
BEST ~ODE FOR CARRYING OUT THE INVENTION
With reference to Figure 1 of the drawings,
an improved apparatus for thermally bonding indicia to
fabric constructed in accordance with the present
invention is generally indicated by 10 and is used for
thermally bonding indicia such as letters, numerals and
slogans to fabric such as T-shirts, sweatshirts, other
garments, etc. As is more fully hereinafter described,
the improved apparatus 10 is a manual heat sealing
machine that is simple in construction and makes its use
by an operator very simple.
As shown in Figure 1 of the drawings, the
improved apparatus 10 has relatively movable upper and
lower platens 12,14 with a heat source 16 shown mounted
in the upper platen for heating it. A lift lever 18
with an over center locking assembly 20 and having a
handle 22 is operated by a human operator to move the
platens 12,14 between open and closed positions.
With continued reference to Figure 1, the
apparatus 10 includes a base 24 and a two piece
cantilever arm 26 including a pivotally mounted lever
arm 27 mounted to the base for pivotal movement of
cantilever arm 26 about an axis A in a horizontal plane
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extending above the base. A swing arm 28 extending from
the cantilever arm 26 and having a knob handle 30 is
graspable by the operator for rotational movement of the
cantilever arm in the horizontal plane above the base
24. A clevis 32 connects the upper platen 12 to the
lift lever 18. Lift lever 18 is connected to the free
end 34 of the lever arm 27 of the cantilever arm 26.
Lower platen 14 is removably mounted on base 24. Lower
platen 14 includes an upwardly facing surface 36 on
which a heat resistant Teflon pad 38 is mounted.
A pressure adjustment assembly 40 including an
adjustment spindle 42 and adjustment knob 44 is used to
vary the pressure between the platens when the platens
are in a closed position. A visual display 46 provides
a visual readout of pressure between the platens 12,14
on a scale of 1 to 9 and also displays operating
instructions and commands in any of various languages
and temperature and time readings. Visual display 46
is connected to a programmable controller 48 which is
able to electronically store and recall numerous
programmed instructions including a plurality of sets of
temperature, pressure and platen closure period
combinations.
A cover 50, shown in a removed position from
apparatus lo, provides a shield against dirt and
protects the controller 48 from unexpected intrusions.
The cover 50 also provides a support for the keypad 52
which is used to interface the operator with the
controller 48 and allow the controller to be programmed.
The keypad 52 includes sixteen buttons 53 for the
operator to access the controller 48.
As shown in Figure 2 of the drawings, the
cantilever arm 26 includes a pressure sensor 54. The
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pressure sensor 54 is a strain gage 56 bonded to the
cantilever arm 26 which in combination therewith creates
a transducer for supplying an electrical signal
proportional to the deflection of the cantilever arm to
indicate the pressure between the upper and lower
platens 12,14 in a closed position. A strain gage of
the type known as Transducer Class strain gage by
Measurements Group of Raleigh, North Carolina has proven
very satisfactory although other strain gages work
equally well.
With continued reference to Figure 2, the
cantilever arm 26 is shown for pivotal movement about
axis A which defines the center of spindle 58. Spindle
58 is rigidly mounted to base 24. Spindle 58 includes
threaded apertures 60 for receiving allen screws 63,
seen in Figure 3 that provide stops for the pivotal
movement of cantilever arm 26. The stops are spaced to
provide directional control of the pivotal movement of
the cantilever arm 26 with respect to base 24 and also
so that the platens 12,14 are stopped in alignment to
close the platens.
Figure 3 illustrates the upper and lower
platens 12,14 in an aligned and open position.
Operation of pressure adjustment 40 is readily seen.
Cantilever arm 26 includes a threaded insert 62 which
receives adjustment spindle 42 having corresponding
threads. The adjustment knob 44, which acts as a
fulcrum between the ends of lever arm 27, is rotated to
change the elevation of the lever arm 27 to thereby
change the pressure between upper and lower platens
12,14 when they are in the closed position, shown in
Figures 1 and 4 or in phantom in Figure 3.
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Figure 3 also illustrates that the lower
platen 14 is provided with a square post 63 received
within a s~uare aperture 64 in base 24 to permit 90-
rotation of the lower platen with respect to the base
for use with various garment applications.
As shown in Figure 4 of the drawings, upper
platen 12 is heated and includes insulation 65 to keep
the upwardly exposed surface 66 of upper platen 12 at
ambient temperature.
Figure 5 of the drawings illustrates the
arrangement of cal-rod heating elements 68 in the upper
platen 12. Preferably, the cal-rod heating elements 68
are spaced uniformly in the upper platen 12 to eliminate
cold spots and create an even heating surface. Most
preferably, the Cal-Rod heating elements 68 are spaced
uniformly at 1-1/2 inches apart. Preferably, a 3/4
inch thick cast aluminum housing defines the upper
platen 12. A thicker platen prevents warping and heat
fluctuations in production runs.
A temperature sensor 69 is located in the
upper platen 12 to sense the temperature of the heated
platen and relay that information to the controller 48.
Temperature sensor 69 is known as a resistance tempera-
ture detector or RTD and includes a printed circuit
printed on platinum or iron alloy which when heated
undergoes a material chanqe and the electrical resis-
tance of the temperature sensor changes. The tempera-
ture sensed is relayed back to controller 48 which acts
as a thermostat and controls the temperature in the
heated platen 12. The controller 48 is operable to
control the temperature in the platen 12 and also to
display that temperature on the visual display 46 in
either degrees Fahrenheit or degrees Celsius.
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STA 76031 PC
Figure 6 is a fragmentary view of the
cantilever arm 26 and the strain gage 56. As earlier
indicated, the strain gage 56 is bonded to cantilever
arm 26 in such a way that in combination a transducer is
created for providing an electrical signal which
reflects flexure of the lever arm 27 and thereby
indicates the pressure between the upper and lower
platens 12,14 in the closed position. The pressure
sensed is transmitted to controller 48 for visual
display on display 46.
In Figures 7 and 8, an optical switch 70 is
shown mounted to cantilever arm 26. Optical switch 70
is conventionally known as a reflective opto sensor and
generates low intensity infrared light. The infrared
light is reflected off the lift lever 18 when the lift
lever is brought down to close the platens 12,14 as
shown in Figure 8 in solid outline. The same optical
switch 70 receives back the reflected light and sends a
signal to the controller 48 to indicate that the platens
12,14 are closed and to initiate a timing sequence. A
switch such as a TRW reflective opto sensor is suitable
for functioning as optical switch 70 although other
switches are contemplated for use in the apparatus 10.
Figure 9 is a schematic of the electrical
components of apparatus 10. Power is supplied to
appara~us 10 by a power cord assembly 72 which includes
a plug 74 suited for the appropriate electrical outlet
of a given power source. The power cord assembly 72
also includes fuses 76 to prevent any overload to
apparatus 10. A switch 78 is included to turn the
power to apparatus 10 on and off. A terminal strip 80
which separates the incoming electrical power can be
wired to receive and distribute either 110 volt current
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or 220 volt current for use with the apparatus 10. The
incoming power is supplied via the foregoing to program-
mable controller 48 to thereby control and monitor the
operation of the apparatus 10. Controller 48 is a
microprocess base controller that operates on low
voltage D.C. current and includes a program chip.
Controller 48 monitors pressure sensor 54 and displays
pressure between platens 12,14 in the closed position on
the visual display 46.
Controller 48 receives a signal from the
reflective optical switch 70 to initiate a timing
sequence and actuate an alarm at the conclusion of the
timing cycle. Controller 48 also monitors the tempera-
ture sensor 69 for controlling the temperature of the
heated platen 12. A shield 82 is shown on the wiring to
the temperature sensor 69 to keep interference from
effecting the signal from the sensor. A power control
module 84, conventionally known as a triac, switches the
low voltage of the controller to the incoming voltage at
the plug 74 to power the cal-rods 68 in platen 12. An
overtemperature switch 86 opens the circuit to the
heated platen 12 if and when the temperature of the
platen becomes too hot.
The keypad 52 is connected to the controller
48 and allows the operator to input instructions with
respect to platen temperature and time. Keypad 52
includes a chip with nine programmed memories for
electronically storing and recalling nine sets of
temperature, pressure and platen closure period
combinations. Keypad 52 allows the operator to program
the controller 48 for additional time, temperature and
pressure settings as desired. Keypad 52 includes a
calendar clock, not shown, to allow the operator to
preprogram the controller 48 to automatically start the
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apparatus 10 and similarly automatically shut off the
apparatus.
ODeration of the Ap~aratus
Apparatus 10 is started by plugging the
machine into an electrical power supply and turning
switch 78 on. Apparatus 10 then greets the operator by
displaying ~Hello~ in the language of choice on the
visual display 46. The visual display 46 then displays
the time, date, and day, also in the language of choice.
Apparatus 10 then asks the operator via the visual
display 46 to ~please wait~ again in the language of
choice and displays the actual temperature and the
preprogrammed temperature setting. The heating platen
12 is preprogrammed to heat to 330-F or 165.5C, the
most common temperature setting used when applying
letters, numbers, and logos to garments.
The operator uses the keypad 52 to select a
desired time, temperature and pressure combination.
This can be done by individually inserting the time and
temperature or by selecting one of the preprogrammed
settings and pushing a single button 53. When the
apparatus 10 is ready to print, ~ready to print~ is
displayed on the visual display 46. The garment on
which the indicia is to be bonded is placed on the
Teflon pad 38 which covers the upwardly facing surface
36 of the lower platen 14 to make the appropriate
pressure adjustment and also to preheat the garment.
The handle 22 on lift lever 18 is pulled down toward the
operator to close the upper and lower platens 12,14.
When the platens 12,14 are in the closed position, the
visual indicator 46 displays the pressure between the
platens on a scale of from one to nine. This scale is
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used to make operation of apparatus 10 as simple as
possible.
After the pressure is adjusted the handle 22
is grasped and lift lever 18 is lifted to separate the
platens 12,14 so that the indicia can be placed on the
preheated garment. With the indicia in place, the
platens 12,14 are again closed and the timing sequence
is initiated by the optical switch 70. When the
duration of the preprogrammed timing sequence is
complete, an alarm sounds and the visual indicator 46
displays the words ~lift lever now~ in the language of
choice and the indicia is bonded to the garment.
While the best mode for carrying out the
invention has been described in detail, those familiar
with the art to which this invention relates will
recognize alternative ways or practicing the invention
as defined by the following claims.
