Dampening fluid evaporator and method
OwnerHarold P. Dahlgren, James E. Taylor +1inventors
InventorsHarold P. Dahlgren, James E. Taylor, Dwight W. Peters
Life of this patent
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Abstract
A method and apparatus to ink and dampen a lithographic printing plate wherein one or more of four disclosed embodiments of a dampening fluid evaporator device directs a continuous stream of air or other drying fluid along the length of a single resilient inking form roller (22) to remove dampening fluid from the roller (22) while leaving substantially dry ink on the roller surface.
Claims13
A method of inking a lithographic printing plate wherein dampening fluid having a viscosity of approximately one centipoise, is applied to the printing plate to render hydrophilic, non-image areas, on the printing plate ink rejecting;
- and wherein ink, having a viscosity significantly greater than 10 poise, is applied by a single inking form roller, having a resilient surface, to oleophilic, image, areas on the printing plate at an inking nip, the improvement comprising the steps of:
- positioning a doctor blade in pressure indented relation with the resilient surface of the inking roller to engage ink and dampening fluid on the portion of the surface of the inking roller which has applied ink to the printing plate and before fresh ink is applied to the portion of the inking roller surface;
- positioning the metering surface of the doctor blade at an angle relative to a line tangent to the roller surface to remove liquid having a viscosity less than a predetermined viscosity from the surface of the inking roller and to leave liquid having a viscosity greater than the predetermined viscosity on the surface of the inking roller;
- directing a stream of drying fluid to engage the surface of the from roller to evaporate dampening fluid which passes the doctor blade;
- rotating a roller in pressure indented relation with the single inking form roller to form a matte surface on the film of liquid on the form roller from which liquid has been removed by the doctor blade;
- and applying fresh ink having a viscosity greater than said predetermined viscosity to the portion of the inking form roller surface from which liquid having a viscosity less than said predetermined viscosity has been removed.
A method of inking a lithographic printing plate wherein dampening fluid having a viscosity of approximately one centipoise, is applied to the printing plate to render hydrophilic, non-image areas, on the printing plate ink rejecting;
- and wherein ink, havinq a viscosity significantly greater than 10 poise, is applied by a single inking form roller, having a resilient surface, to oleophilic, image, areas on the printing plate at an inking nip, the improvement comprising the steps of:
- positioning a doctor blade in pressure indented relation with the resilient surface of the inking form roller to engage ink and dampening fluid on the portion of the surface of the inking form roller which has applied ink to the printing plate and before fresh ink is applied to the portion of the inking form roller surface;
- positioning the metering surface of the doctor blade at an angle relative to a line tangent to the roller surface to remove liquid havinq a viscosity less than a predetermined viscosity from the surface of the inking form roller and to leave liquid having a viscosity greater than the predetermined viscosity on the surface of the inking form roller;
- directing a stream of drying fluid to engage the surface of the form roller to evaporate dampening fluid which passes the doctor blade;
- rotating a roller in pressure indented relation with the single inking form roller to form a matte surface on the film of liquid on the inking form roller from which liquid has been removed by the doctor blade;
- directing a second stream of drying fluid to said inking form roller to evaporate dampening fluid remaining in the film of liquid;
- and applying fresh ink having a viscosity greater than said predetermined viscosity to the portion of the inking form roller surface from which liquid having a viscosity less than said predetermined viscosity has been removed.
A method of inking a lithographic printing plate comprising the steps of:
- providing a source of ink which is substantially free of dampening fluid;
- applying a film of ink from the source to the surface of a form roller at an ink metering nip to form a film of ink which is substantially free of dampening fluid;
- forming a dampening fluid receptive surface on the metered film of ink;
- applying dampening fluid at a dampening nip to the dampening fluid receptive surface on the film of ink;
- rotating the form roller to transfer ink and dampening fluid at an inking nip to the printing plate;
- urging a doctor blade into pressure indented relation with the form roller surface;
- establishing an angular relationship between the doctor blade and the surface of the form roller to remove dampening fluid from ink remaining on the form roller after the form roller has transferred ink and dampening fluid to the printing plate at the inking nip and before the ink metering nip;
- directing a high velocity air stream to impinge against the ink to evaporate dampening fluid not removed by the doctor blade;
- and
- forming a matte surface on the ink subsequent to impingement of the air stream thereagainst.
An inker for a lithographic printing press wherein a dampener applies dampening fluid to a lithographic printing plate to render hydrophilic non-image areas on the printing plate ink rejecting, and wherein an inker applies ink having a viscosity significantly greater than the viscosity of the dampening fluid to the lithographic printing plate, the improvement comprising:
- a resilient inking form roller;
- a doctor blade having a metering surface;
- means positioning the doctor blade into pressure indented relation with the inking form roller with the metering surface of the doctor blade at an angle relative to a line tangent to the roller to efficiently remove dampening fluid having a viscosity less than a predetermined viscosity from the roller surface and leaving ink on the form roller surface having a viscosity greater than the predetermined viscosity;
- means directing a stream of drying fluid to evaporate dampening fluid from the surface of the inking form roller;
- and means to apply a film of fresh ink on the inking form roller.
An inker for a lithographic printing press comprising a roller having a resilient outer surface and means operative, upon rotation of the roller, for forming, from a liquid film of ink of irregular thickness carried by the roller, a thin liquid film of ink of uniform thickness, said means comprising a metering member pressed substantially radially inwards of the roller, said metering member having a metering edge and a trailing edge and presenting to the irregular liquid film, a substantially flat metering surface on the metering member adjacent the metering edge;
- means urging both the metering edge and the trailing edge into indented relation with the resilient roller surface;
- means applying dampening fluid to a film of ink formed by the metering member;
- and evaporator means having an elongated slot to direct a continuous high velocity stream of air across the length of the roller in a direction substantially tangentially of the roller and opposite to the direction of movement of the roller surface to evaporate dampening fluid from an irregular film of ink and dampening fluid remaining on the form roller after inking the printing plate.
Dependencies are inferred from the claim text.