Device for micro-embossing of paper and paper processing line comprising said device
A device for micro-embossing paper includes at least one micro-embossing unit to micro-emboss a wet paper ply. The micro-embossing unit includes a micro-embossing cylinder and a counter cylinder facing the micro-embossing cylinder at an embossing area where the wet paper ply is subjected to micro-embossing, and a heater to dry the wet paper ply. The micro-embossing cylinder includes a side surface partially wrapped by the wet paper ply. The heater heats at least one portion of the side surface partially wrapped by the wet paper ply to dry the wet paper ply.
1. A device for micro-embossing paper, comprising:
at least one micro-embossing unit configured to micro-emboss a wet paper ply, said micro-embossing unit comprising:
a steel micro-embossing cylinder and a rubber counter cylinder facing said steel micro-embossing cylinder at an embossing area where said wet paper ply is subjected to micro-embossing, and
heating means configured to dry said wet paper ply,
wherein said steel micro-embossing cylinder comprises a side surface partially wrapped by said wet paper ply over a wrapping angle comprised between 120° and 300°,
wherein said heating means are configured to heat at least one portion of said side surface partially wrapped by said wet paper ply to dry said wet paper ply,
wherein said at least one micro-embossing unit comprises at least one motorised return roller, and a path of said at least one wet paper ply being in contact with said rubber counter cylinder exclusively at said embossing area, and
wherein axes of rotation of said steel micro-embossing cylinder and said rubber counter cylinder lie in a same substantially horizontal plane.
2. The device for the micro-embossing of paper according to claim 1 , wherein said side surface is wrapped by said wet paper ply over a wrapping angle comprised between 180° and 270°.
3. The device for the micro-embossing of paper according to claim 1 , wherein said side surface is wrapped by said wet paper ply over a wrapping angle greater than 210°.
4. The device for the micro-embossing of paper according to claim 1 , wherein said heating means are housed inside said steel micro-embossing cylinder and are configured to heat from within said side surface of said steel micro-embossing cylinder.
5. The device for the micro-embossing of paper according to claim 1 , wherein said heating means are housed outside said steel micro-embossing cylinder and face said side surface of said steel micro-embossing cylinder to heat said heated portion of said side surface partially wrapped by said wet paper ply.
6. The device for the micro-embossing of paper according to claim 1 , wherein said heating means comprise an electrical resistor, or an oil, water or steam heating system, or an electromagnetic induction heater, or a hood conveying a flow of hot air.
7. The device for the micro-embossing of paper according to claim 1 , further comprising a plurality of said micro-embossing units adapted to operate in parallel.
8. The device for the micro-embossing of paper according to claim 1 , wherein said rubber counter cylinder comprises on the side surface a plurality of incisions configured to be coupled to micro-embossing reliefs present on said steel micro-embossing cylinder.
9. The device for the micro-embossing of paper according to claim 1 , wherein said rubber counter cylinder is activated in rotation in a synchronised way with the rotation of said steel micro-embossing cylinder.
10. The device for the micro-embossing of paper according to claim 1 , wherein said rubber counter cylinder is activated in rotation by gears that draw the rotation motion from said steel micro-embossing cylinder.
11. A paper processing line comprising:
an unwinding station for unwinding at least two paper plies;
a wetting station for wetting at least one of said at least two paper plies, adapted to wet said at least one paper ply to obtain at least one wet paper ply;
a micro-embossing station for micro-embossing said at least one wet paper ply, comprising the device for the micro-embossing of paper according to claim 1 , configured to micro-emboss said at least one wet paper ply to obtain at least one micro-embossed paper ply;
a joining station for joining said at least one micro-embossed paper ply with a second micro-embossed paper ply or with said at least one paper ply, to obtain a paper with multiple plies at least one of which is micro-embossed; and
a rewinding station for rewinding said multi-ply paper.
12. A method for the micro-embossing of paper comprising:
wetting at least one paper ply to obtain at least one wet paper ply;
embossing said at least one wet paper ply between one steel micro-embossing cylinder and a rubber counter cylinder in an embossing area;
heating said at least one wet paper ply to dry said at least one wet paper ply;
at least partially wrapping said at least one wet paper ply around the side surface of said steel micro-embossing cylinder over a wrapping angle comprised between 120° and 300°;
heating at least one portion of said side surface partially wrapped by said wet paper ply to dry said wet paper ply; and
returning said at least one wet paper ply by at least one motorised return roller and contacting said at least one wet paper ply with said rubber counter cylinder exclusively at said embossing area,
wherein axes of rotation of said steel micro-embossing cylinder and said rubber counter cylinder lie in a same substantially horizontal plane.