Printing – Antismut device – Anti-offset material application
Patent
1997-07-12
1998-10-20
Burr, Edgar S.
Printing
Antismut device
Anti-offset material application
B41F 2306
Patent
active
058231129
DESCRIPTION:
BRIEF SUMMARY
This is a 371 of PCT/EP96/04635, filed on Oct. 25, 1996.
The invention relates to a powder dusting apparatus for a printing machine, having air is directed towards the printed products moved past by gripping devices of the transport system of the printing machine; mixture of powder and carrying air; nozzles.
Powder-dusting apparatuses of that kind serve to provide printing machine products which are coming from the print unit and which have passed through a drying zone with a coating of powder, which prevents the printed products from sticking together during the stacking operation that follows. For that purpose the powder-dusting apparatuses are arranged in the vicinity of the plane of transport of the printed products so that their nozzles are able to apply a mixture of air (carrying air) and powder to the printed products. Generally speaking, the transport systems of printing machines are formed by parallel endless conveyor chains which are joined to one another by a plurality of gripping devices. The gripping devices comprise a gripping mechanism, which is able to hold the printed products at their edge, and project beyond the plane of transport of the printed products. In known powder-dusting apparatuses, the nozzles therefore have to be a comparatively large distance from the plane of transport so that the gripping devices are able to get past. This large distance has the disadvantage, however, that the mixture of powder and carrying air that is expelled from the nozzles spreads out uncontrollably in the printing machine.
It is the aim of the present invention to construct a powder-dusting apparatus of the kind mentioned in the introduction in such a manner that the mixture of powder and carrying air can be applied in a spatially concentrated manner to the printed products.
That problem is solved according to the invention by between two positions, namely, of the printed products of the printed products, control means co-operates with the lifting device such that the latter brings the nozzles into the first position as long as gripping device is in the vicinity of the nozzles, and brings the nozzles into the second position when the gripping device is located an adequate distance from the nozzles.
According to the invention, the nozzles of the powder-dusting apparatus are therefore no longer fixedly mounted. On the contrary, they are given a mobility perpendicular to the plane of transport of the printed products so that they are able to "make way" for gripping devices approaching them, that is, maintain a correspondingly large distance from the plane of transport in the comparatively short period in which the gripping devices travel past beneath the nozzles. As soon as the gripping device has passed the nozzles, however, these return to a position in which they are very close to the plane of transport and thus to the surfaces of the printed products to be dusted. The proximity of the nozzle openings to the printed products allows a more controlled dusting than was previously possible with known powder-dusting apparatuses.
The lifting device and the control means alike can be realised in many different ways. In a first exemplary embodiment of the invention, both lifting device and control means are mechanically constructed and combined with one another. They are distinguished in that the lifting device and the control means are combined in a cam mechanism which comprises: transport system; with the cam surface; positions.
In this practical form, the relative position of the gripping devices on the transport system and the nozzles is mechanically detected; the lifting mechanism requires no special driving means and the control means requires no power supply of its own. This exemplary embodiment is especially robust and not susceptible to faults.
It is preferred therein that two parallel cam surfaces are provided, which form a cam track in which the cam follower is received. The two parallel cam surfaces guide the cam follower in both possible directions of movement, so that the latter is able to fulfi
REFERENCES:
patent: 1555797 (1925-09-01), Grammer
patent: 4332198 (1982-06-01), Schmoeger
patent: 4449453 (1984-05-01), Staffer et al.
patent: 4807528 (1989-02-01), Schmoeger et al.
patent: 5001980 (1991-03-01), Aoki et al.
Burr Edgar S.
Grafix Zerstaubungstechnik GmbH
Sandusky Amanda B.
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