Printing – Antismut device – Anti-offset material application
Patent
1997-08-06
1999-10-12
Burr, Edgar
Printing
Antismut device
Anti-offset material application
101419, B41F 3500
Patent
active
059641550
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus for powdering printed products according to the precharacterising clause of claim 1.
In known powdering apparatus of that kind, the metered powder stream delivered from the powder reservoir is distributed in a carrier gas stream, and the powder mist so produced is fed to a nozzle strip extending transversely across the path over which the printed products are conveyed.
Owing to the gripper rods which move the printed products, that nozzle strip has to be arranged at a correspondingly large distance away from the conveying surface of the printed products. That is disadvantageous inter alia because a proportion of the powder mist produced escapes into the printing machine. In addition, only some of the powder particles directed towards the printing inks cling to the printing inks which have not yet dried completely.
By means of the present invention an apparatus according to the precharacterising clause of claim 1 is to be so developed that improved efficiency in the distribution of the metered powder stream over the surface of the printed products is achieved therewith.
That problem is solved according to the invention by a powdering apparatus having the features mentioned in claim 1.
In the case of the powdering apparatus according to the invention, powder particles are applied by a powder feeding element to the surface of an application roller.
The application roller has a circumference corresponding to the distance between successive gripper rods and is furthermore provided with a recess which is able to receive a gripper rod. The movement of the application roller is so synchronized with that of the gripper rods that gripper rods and recess arrive at the same time in the gap created between the application roller and the support element which supports the reverse side of the printed products. Since the application roller cooperates with the printed side of the printed products in a frictional connection, powder particles held on the circumferential surface of the application roller are transferred to the printed products very effectively. Since the feeding element, which in turn applies the powder particles to the circumferential surface of the application roller, is arranged outside the path of the gripper rods, it is not necessary to provide a large gap between its outlet end and the circumferential surface of the application roller.
The powdering apparatus according to the invention therefore operates very reliably with reduced powder consumption and with a reduction in the surrounding portions of the printing machine.
Advantageous developments of the invention are indicated in subclaims.
With the development of the invention according to claim 2, especially gentle transport of the printed products in the region of the application roller is obtained. In addition, the perpendicular force prevailing in the nip and acting on the printed products can be selected to be greater than when the reverse side of the printed products is supported by a plate-shaped stationary support element with sliding friction.
The development of the invention according to claim 3 is also advantageous with regard to exerting a relatively high application force of the powder particles.
As a result of the development of the invention according to claim 5, the printed products do not have to travel through sharp curves in the region of the powdering apparatus.
The development of the invention according to claim 6 is advantageous with regard to removing small residual amounts of powder which become detached from the surface of the application roller on the way between the feeding element and the nip between the application roller and the support element and of powder particles that are not properly transferred from the feeding element to the application roller.
The development of the invention according to claim 7 ensures that, between the feeding element and the path of the application roller between the application roller and the support element, the circumferential surface of the applicatio
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Burr Edgar
Nguyen Anthony H.
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