Magnetic cylinders with image plate or blanket for offset printing
AssigneeR. R. Donnelley & Sons Company
InventorAndres Peekna
Life of this patent
Estimating the term…
Abstract
Magnetic cylinders with an image plate or an offset blanket carrier plate have annular pole pieces and magnets which maximize either the resistance of the plate to peel-off or the attractive force intensity with a nominal displacement of the plate from the cylinder for typical operating conditions. The plates are precurved, preferably with a radius slightly less than the cylinder radius.
Claims27
A magnetic cylinder and plate of magnetic material for printing, in which the peripheral surface of the cylinder has alternate annular magnets and pole pieces, the magnets having a magnetic orientation axially of the cylinder, adjacent magnets being of opposite polarity, the magnets defining with the pole pieces a plurality of magnetic circuits, the plate being wrapped around the cylinder and completing the magnetic circuits between adjacent pole pieces, the plate being subject to edge peel-off from an outwardly directed force at the plate edge, the improvement that the magnetic circuits are characterized by:
- a magnet width axially of the cylinder and a corresponding pole piece spacing axially of the cylinder to maximize the term ##EQU27## where w.sub.0 is the magnetic attractive force exerted on an area of the plate with no displacement between the plate and the cylinder surface and
- k is the magnitude of the slope of the linear portion of a plot of w, the magnetic attractive force exerted on the plate area as displacement of the plate area from the cylinder increases.
A magnetic cylinder and resilient blanket bonded to a carrier plate of magnetic material for offset web printing, in which the peripheral surface of the cylinder has alternate annular magnets and pole pieces, the magnets having a magnetic orientation axially of the cylinder, adjacent magnets being of opposite polarity, the magnet defining with the pole pieces a plurality of magnetic circuits, with the blanket and carrier plate being wrapped around the cylinder, the carrier plate completing the magnetic circuits between adjacent pole pieces, the carrier plate and blanket being susceptible to circumferential movement around the cylinder as the blanket is subjected to localized pressure from another cylinder in a nip, the improvement that the magnetic circuits are characterized by:
- a magnet width axially of the cylinder and a corresponding pole piece spacing axially of the cylinder to maximize the attractive force exerted on the carrier plate with nominal displacement between the carrier plate and the cylinder surface.
Dependencies are inferred from the claim text.