| CPC B29C 65/38 (2013.01) [B29C 65/22 (2013.01); B29C 65/32 (2013.01); B29C 65/7894 (2013.01); B29C 66/0044 (2013.01); B29C 66/431 (2013.01); B29C 66/53262 (2013.01); B29C 66/72341 (2013.01); B29C 66/81811 (2013.01); B29C 66/8511 (2013.01); B29L 2031/7128 (2013.01)] | 18 Claims |
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1. A sealing system for heat sealing of heat-sealable film material,
wherein the sealing system comprises:
an infeed section comprising a roll handling station that is configured to receive one or more rolls of heat-sealable film material, which infeed section is configured to dispense superimposed walls of heat-sealable film material unwound from one or more rolls,
a sealing section downstream of the infeed section and comprising two or more sealing stations arranged in series along a linear path for the superimposed walls dispensed from the infeed section,
a film material drive station downstream of the linear path through the sealing section, which film material drive station is configured to pull the superimposed walls of heat-sealable film material at a constant velocity along the linear path past the sealing stations,
wherein each sealing station comprises:
a sealing device comprising a first jaw and a second jaw,
an actuator device that is configured to move the first and second jaws relative to one another between an opened position and a clamped position,
wherein the first jaw has a first front surface configured to contact a respective first wall of heat-sealable material, and wherein the second jaw has a second front surface configured to contact a respective second wall of heat-sealable material, wherein at least the first jaw comprises at a heatable member for heat sealing a region of the superimposed walls of heat-sealable film material when clamped between the first and second jaws,
a motion device that is configured to move the first and second jaws in synchronicity with the superimposed walls when clamped between the first and second jaws,
wherein the sealing system further comprises a control unit which is associated with the sealing stations,
characterized in that,
at least each first jaw of each sealing station comprises at the respective front surface thereof at least one heatable member embodied as a susceptor element comprising electrically conductive material, which impulse heatable member extends along the respective front surface,
and in that, for each pair of first and second jaws of each sealing station, at least one of the jaws thereof comprises an inductor,
and in that the system comprises a high frequency electric current source which is connected to the inductor,
and in that the system comprises at least one cooling device that is configured to continuously cool at least one of the first and second jaws of each sealing station,
and in that the cooling device comprises one or more cooling ducts in said at least one of the first and second jaws of each cooling station,
and in that the one or more cooling ducts are arranged at a rear side of the inductor,
and in that the cooling device is configured to establish a continuous circulation of liquid coolant through the one or more cooling ducts,
and in that each sealing station is configured to perform an integrated impulse sealing and cooling cycle, wherein the respective actuator device is operated to move the respective first and second jaws into the clamped position in which the first and second walls are clamped by the first and second jaws, and wherein, in the clamped position, the high frequency electric current source temporarily feeds a high frequency electric current to the inductor, thereby generating a high frequency electromagnetic field with the inductor, wherein the high frequency electromagnetic field induces eddy currents in the susceptor element generating an impulse of heat that is emitted by the susceptor element, which impulse of heat has a heat impulse duration and seals the region of the first and second walls to each other or onto a fitment when present, wherein after termination of the feeding of high frequency electric current to the inductor the at least one of the first and second jaws as well as the sealed region are effectively cooled by the cooling device during a clamped cooling duration whilst the respective first and second jaws remain in the clamped position, and wherein the actuator device is operated to move the first and second jaws into the opened position after the clamped cooling duration,
and in that the control unit is, for each one of the sealing stations independently, configured to control the feeding of high frequency electric current to the inductor and thereby the impulse of heat emitted by the susceptor element,
and in that the control unit is, for each of the sealing stations independently, configured to control the actuator device for moving the first and second jaws relative to one another between the opened position and the clamped position allowing to control the duration of the clamped position of the first and second jaws and thereby the clamped cooling duration.
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