Casting apparatus and method to check a thickness of a cast sheet
The invention relates to a casting apparatus ( 1 ) for the production of a cast sheet ( 10 ) of homogenized tobacco material, said casting system comprising: ⋅a casting box ( 4 ) adapted to contain a slurry of the homogenized tobacco material; ⋅a movable support ( 7 ); ⋅a casting system adapted to deposit the slurry contained in the casting box ( 4 ) onto the movable support ( 7 ) so as to form the cast sheet ( 10 ); ⋅a sensor ( 30 ) to detect a thickness of the cast sheet ( 10 ); ⋅wherein the sensor ( 30 ) includes a slider ( 33 ) comprising a planar surface ( 36 ) adapted to be in contact to a top surface of the cast sheet and a height detector ( 38 ) adapted to measure the height of the planar surface ( 36 ) so as to derive the thickness of the cast sheet ( 10 ). The invention also relates to a method to measure the thickness of a homogenized tobacco sheet ( 10 ).
1. Casting apparatus for the production of a cast sheet of homogenized tobacco material, said casting apparatus comprising
a casting box adapted to contain a slurry of the homogenized tobacco material;
a movable support;
a casting system adapted to deposit the slurry contained in the casting box onto the movable support so as to form the cast sheet;
a sensor to detect a thickness of the cast sheet,
wherein the sensor includes:
a slider comprising a planar surface adapted to be in contact to a top surface of the cast sheet; and
a height detector adapted to measure the height of the planar surface so as to derive the thickness of the cast sheet; and
a drying unit, the slider being positioned downstream the drying unit, in the direction of motion of the movable support.
2. The casting apparatus according to claim 1 , wherein the casting system includes a casting blade adapted to cast the slurry onto the movable support, a distance separating said casting blade from said support.
3. The casting apparatus according to claim 1 , wherein the casting system includes two casting rollers forming a gap therebetween, said gap being positioned below said casting box.
4. The casting apparatus according to claim 1 , including a pressing device adapted to press said planar surface towards the cast sheet.
5. The casting apparatus according to claim 4 , wherein said pressing device includes an air pressure generator and a nozzle, said nozzle being adapted to eject compressed air towards the slider so as to press said planar surface towards the movable support.
6. The casting apparatus according to claim 5 , including an air pressure regulator to vary a pressure value of the compressed air exiting the nozzle.
7. The casting apparatus according to claim 1 , comprising a plurality of sliders positioned one parallel to the other.
8. The casting apparatus according to claim 7 , wherein the plurality of sliders is positioned in a row formed perpendicularly to a direction of motion of the movable support.
9. The casting apparatus according to claim 7 , wherein a distance between two adjacent sliders perpendicularly to the direction of motion of the movable support is comprised between about 0 centimeters and about 200 centimeters.
10. The casting apparatus according to claim 1 , wherein the planar surface includes a rectangular surface.
11. The casting apparatus according to claim 10 , wherein a side of the rectangular surface is positioned perpendicular to a direction of motion of the movable support.
12. The casting apparatus according to claim 1 , wherein said height detector is adapted to measure the height of the planar surface with reference to the movable support.
13. The casting apparatus according to claim 1 , including a control unit connected to the sensor, the control unit being adapted to determine variations in height of said slider on the basis of signals sent by the sensor.