Method of manufacturing a hydrophilic roll in which a hard metal is ground during manufacturing to provide a polished finish, the finish measured to determine the number of peaks and valleys and grinding continued with a finer grinding wheel until the peaks and valleys which exceed 5 micro-inches from a center line for the peaks and valleys are less than ten per inch of length and those which deviate more than 2.5 micro-inch from the center line number less than 100 per inch. The roll is then treated to render it hydrophilic.
Application to areas of the successive rollers and cylinders in a printing press, of liquid from the water duct which will not eventually be transferred to the material being printed, is avoided by using a vibrator roller and at least one damper roller of the same width as the sheet of material being printed, while the oscillator roller, the plate cylinder, the blanket cylinder and the impression cylinder are wider than the sheet.
A covering for sheet-supporting cylinders and drums on rotary offset printing machines for printing both on single and both sides of a sheet, the covering having a smooth surface on one side thereof and a textured surface on the opposite side thereof, with sheet-supporting surfaces projecting from the textured surface and formed of hydrophilic and chemically and wear-resistant material includes a device for defining perforations formed in the textured surface, and a device connected to the perforations for selectively applying blowing air and suction therethrough.
A dampening system for a printing apparatus includes a print plate, a printing cylinder contacting the print plate and adapted to supply water to the print plate, a feed device for feeding water to the printing cylinder, and a dampening roller adapted to transfer water from the feed means to the printing cylinder. The dampening roller comprises a roller having a dampening layer composed of a substrate through which is dispersed a plurality of minute hollow bodies. A plurality of the hollow bodies open towards the circumferential surface to form cells for transferring the water from the feed means to the printing cylinder. At least one of the size and the concentration of the hollow bodies dispersed within the substrate is selected depending on the amount of dampening water to be fed to the print plate.
A machine for printing letters, numbers, symbols and the like on banding or other flexible material of extended length includes a drive wheel and a printing wheel, as well as pressure rollers for pressing the banding against the two wheels. The drive wheel is driven by the banding as the banding is drawn through the machine, and the printing wheel is connected to the drive wheel through a belt such that the two wheels have the same peripheral velocity. Thus, the printing wheel, which has raised characters around its periphery, rotates as the banding passes over it. The raised characters of the printing wheel further pass over the periphery of an ink transfer wheel, all but a small segment of which is contained within a sealed case of an inking unit. The surface of the ink transfer wheel is pitted, and where that wheel emerges from the case, seals are provided to form a vapor barrier which isolates the interior of the case from the surrounding atmosphere. Within the case an ink pick-up wheel lifts ink from a reservoir at the bottom of the case to the ink transfer wheel, from which the ink is transferred to the raised characters on the printing wheel and thence to the banding. The belt further drives the ink pick-up wheel and the ink transfer wheel. A release mechanism is provided which, when operated, withdraws the pressure rollers from the drive and printing wheels, moves the ink transfer wheel away from the printing wheel, and creates slack in the belt.
A fluid transfer roller for use in offset printing for picking up a film of water and transferring it to a printing plate consists of a rigid core with an outer layer of foamed-in-place, partially open-celled foam.
