A method operates a flexographic printing press. The press contains a printing cylinder carrying a sleeve with at least one flexographic printing forme or a flexographic printing cylinder and an impression cylinder forming a printing nip with the printing cylinder to print on a web of printing substrate. The method includes automatically adjusting the transport speed of the web of printing substrate as a function of a dot density of the flexographic printing forme, i.e. of a location-dependent density of printing elevations on the flexographic printing forme, or of data computationally derived therefrom, or as a function of gaps of the flexographic printing forme or printing cylinder or data computationally derived therefrom. The printing press advantageously provides a cost-efficient way of producing high-quality prints in an industrial flexographic printing process while avoiding undesired vibration. In addition, the method of the invention advantageously provides further automation of the printing process.

A printing machine for printing on a printing substrate web includes a plurality of inline flexographic printing units which are disposed in a plane accessible to an operator of the machine. Each one of the two flexographic printing units of a respective duplex printing station includes a respective impression cylinder and a dryer disposed between the two impression cylinders along a path of web travel of the web of printing substrate. A method of operating the printing machine is also provided.

A method is provided for setting a layer thickness of a covering coating material to be applied to a substrate by an application device. The coating material is applied to the substrate in a printing machine or in a paper-processing machine. The coating material is applied at various points on the substrate by the use of the application device in a machine process. At each of at least one first point on the substrate, the coating material is applied in a grid having a plurality of grid points, and at each of at least one other second point on the substrate, the coating material is applied over the full area. Each first point on the substrate forms a grid zone and each second point on the substrate forms a solid zone. A control unit connected to a sensing device determines respective values of the optical density of the layer of the coating material applied on the points on the substrate using data captured by the sensing device at the first and second points on the substrate. The control unit defines the layer thickness of the coating material currently applied to the substrate by the application device in an ongoing machine process. At the defined thickness, the value of the optical density determined in a grid zone corresponds to the value of the optical density determined in a solid zone, as the layer thickness of the coating material having an opacity of 100%.

A method of operating a flexographic printing press having a printing cylinder carrying a sleeve with at least one flexographic printing forme or a flexographic printing cylinder, and an impression cylinder, includes adjusting contact pressure between the printing cylinder or the flexographic printing cylinder and the impression cylinder by motor. The adjustment is made in an automated way as a function of a dot density of the flexographic printing forme, i.e. of a location-dependent density of printing elevations on the flexographic printing forme or data computationally derived therefrom. A cost-efficient way of producing high-quality prints in an industrial flexographic printing process is thus provided. In addition, the method advantageously provides further automation of the printing process. A flexographic printing press, a flexographic printing press system, and a flexographic printing forme or sleeve for a flexographic printing forme are also provided.

The invention relates to a method for checking a printing cylinder for defects in an engraved cylinder surface of the printing cylinder, comprising the steps: capturing a first and at least one further digital image of a cylinder surface of a printing cylinder by means of an optical capture unit, wherein the cylinder surface is cleaned before capturing the at least one further image, comparing the digital images each with a digital engraving master of the printing cylinder, the comparing comprising: determining deviations between each of the digital images and the digital engraving master, and checking the determined deviations for matching deviations between the digital images,
wherein a pseudo defects is concluded if no matching deviations between the digital images have been detected when comparing, and wherein an engraving defect on the printing cylinder is concluded in the case of matching deviations. Furthermore, a corresponding arrangement is described.

The invention relates to a method for verifying a printing plate, specifically a gravure cylinder, for errors in an engraving of the printing plate, comprising the following steps: Generating at least two proofs using a printing plate to be verified, capturing at least one digital image each of the at least two proofs with an image-capturing unit, comparing each of the digital images of the at least two proofs with the engraving template of the printing plate, wherein the comparison comprises the following steps: Detecting deviations between each of the images and the engraving template, and verifying that the detected deviations occur in identical fashion on the digital images of all of the at least two proofs, wherein a pseudo error is indicated if the comparison does not show identical deviations between the digital images of the at least two proofs, and wherein identical deviations indicate an engraving defect in the printing plate.

A method is provided for setting a layer thickness of a covering coating material to be applied to a substrate by an application device. The coating material is applied to the substrate in a printing machine or in a paper-processing machine. The coating material is applied at various points on the substrate by the use of the application device in a machine process. At each of at least one first point on the substrate, the coating material is applied in a grid having a plurality of grid points, and at each of at least one other second point on the substrate, the coating material is applied over the full area. Each first point on the substrate forms a grid zone and each second point on the substrate forms a solid zone. A control unit connected to a sensing device determines respective values of the optical density of the layer of the coating material applied on the points on the substrate using data captured by the sensing device at the first and second points on the substrate. The control unit defines the layer thickness of the coating material currently applied to the substrate by the application device in an ongoing machine process. At the defined thickness, the value of the optical density determined in a grid zone corresponds to the value of the optical density determined in a solid zone, as the layer thickness of the coating material having an opacity of 100%.

A method for the determination of print parameters of a printing machine, particularly a flexographic printing machine, comprises the following steps: First, a print form (12) is provided and mounted on a print cylinder (14). Then, at least one high-resolution image of the surface of the print form (12) is recorded by means of a 3D camera (18). On the basis of the at least one high-resolution image a height profile of the print form (12) is determined and then a simulated print image is calculated on the basis of the height profile and an initial set of print parameters. Finally, optimized print parameters are determined by checking and/or varying the print parameters of the initial set. For this purpose, a simulated print image is calculated again after the print parameters have been varied.

In addition, a test stand is specified on which such a method can be carried out.

The invention relates to a method for verifying a printing plate, specifically a gravure cylinder, for errors in an engraving of the printing plate, comprising the following steps: Generating at least two proofs using a printing plate to be verified, capturing at least one digital image each of the at least two proofs with an image-capturing unit, comparing each of the digital images of the at least two proofs with the engraving template of the printing plate, wherein the comparison comprises the following steps: Detecting deviations between each of the images and the engraving template, and verifying that the detected deviations occur in identical fashion on the digital images of all of the at least two proofs, wherein a pseudo error is indicated if the comparison does not show identical deviations between the digital images of the at least two proofs, and wherein identical deviations indicate an engraving defect in the printing plate.

The present invention discloses a digital ink duct for a printing press, comprising an ink tank for storing ink, a main ink pipe that communicates with the ink tank, at least one metering-type ink delivery device, ink delivery pipes, a controller and a signal acquisition device. In the present invention, high-accuracy, metering-type ink delivery devices are arranged in a queue to form a digital ink duct which replaces the traditional ink duct and supplies ink for the ink zones. The present invention can perform accurate adjustment in real time, is high in automation and digitalization degree, and can realize one-way ink delivery and avoid ink return.