Apparatus and method for manufacturing security paper
An apparatus for manufacturing security paper, comprising at least one main forming roller, which is provided with a lower portion or forming portion, which is arranged inside a forming box that contains a paper paste, an upper portion or deposition portion, which is arranged below a collecting wire that can move along an advancement direction and is designed to receive, at a collecting face, the sheet formed on the forming roller, and a device for depositing security elements that is arranged upstream of the main forming roller along the advancement direction of the collecting wire and is adapted to deposit the security elements at the collecting face.
1. An apparatus for manufacturing security paper, comprising at least one main forming roller, which is provided with a lower portion or forming portion, which is arranged inside a forming box that contains a paper paste, and an upper portion or deposition portion, which is arranged below a collecting wire that moves along an advancement direction for receiving, at a collecting face, a sheet formed on said forming roller, further comprising a device for depositing security elements that is arranged upstream of said main forming roller along the advancement direction of said collecting wire and is adapted to deposit said security elements at said collecting face, wherein said device for depositing security elements comprises a supporting structure for at least one feeder or spreader, which is arranged below said collecting wire and is provided with at least one intake port connected to a duct for feeding said security elements and at least one feeding opening, which is arranged so that it substantially faces said collecting face of said collecting wire, and wherein said device for depositing security elements comprises at least one diffuser, which is connected at its output to each feeding duct and at its input to a tank for containing an aqueous solution of said security elements, pumping means being provided for adjusting the pressure of said solution inside said diffuser in order to control the flow-rate of said solution in output from said feeding openings, wherein said device for depositing security elements comprises a suction device, which is arranged on an opposite side of said collecting wire with respect to said feeder and is provided with an intake or suction port that at least faces said feeding opening, and wherein a discharge valve is arranged inside said diffuser, said valve being connected to a discharge duct connected to said tank, so as to be able to recover any aqueous solution of security elements that remains in the diffuser.
2. The apparatus according to claim 1 , further comprising, upstream of said deposition device, a secondary forming roller or former, which is adapted to deposit on said collecting wire a layer of paper, said device for depositing said security elements being adapted to deposit said security elements on said layer of paper conveyed by said collecting wire.
3. The apparatus according to claim 1 , wherein said device for depositing security elements comprises a plurality of said feeders, which are spaced along a direction that is substantially transverse with respect to said advancement direction of said collecting wire.
4. The apparatus according to claim 1 , wherein said pumping means comprise a pump that is adapted to feed a mixture of said aqueous solution and air to said diffuser.