Patent Grant
11173702
This application is the US National Phase, under 35 USC, ยง 371, of PCT/EP2019/071451, filed Aug. 9, 2019; published as WO 2020/043463 A1, on Mar. 5, 2020, and claiming priority to DE 10 2018 121 301.8 filed Aug. 31, 2018, the disclosures of which are expressly incorporated herein in their entireties by reference.
The present invention relates to a method for setting a layer thickness of an opaque 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, coating materials are 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 the respective value for the optical density of the layer of the coating material applied at the point on the substrate from data captured by the sensing device at the first and second points on the substrate.
DE 38 18 405 A1 discloses a method for determining the coloration for the different paper-color combinations used in the printing industry, wherein a uniform color profile is set on the printing machine, the same ink quantity is supplied zonally, and the thickness of the ink application is determined by means of an ink consumption surface of a printing aid.
U.S. 2015/0 090 136 A1 discloses a method for controlling the thickness of an ink film, wherein the ink film is applied to a printed substrate in a lithographic printing machine, which contains a plurality of printing units, wherein each printing unit contains a blanket cylinder, a plate cylinder, a take-off roller, and an inking unit, comprising the following: (a) filling the inking cylinder in one or several of the plurality of printing units of the printing machine in a non-printing position, wherein each printing unit contains a blanket cylinder; moving the removing roller in the one or the several printing units of the plurality of the printing units into contact with the blanket cylinder of the printing unit; and subsequently driving the inking unit, the plate cylinder, the blanket cylinder, and the removing roller and thereby transferring printing ink from the inking unit to the plate cylinder, from the plate cylinder to the blanket cylinder, and from the blanket cylinder to the removing roller; (b) moving the removing roller out of contact with the blanket cylinder of the printing unit in the one or the several printing units of the plurality of printing units; (c) arranging the one or the several printing units in the printing position; (d) printing onto the substrate with the one or the several printing units when the substrate moves through the printing machine; (e) measuring an optical density on the moving substrate with an optical sensor; (f) comparing the measured optical density with a predefined metric and, when the measured optical density is within a predefined metric, continuing the printing on the substrate and, when the measured optical density is outside of the predefined metric, repeating steps (a) to (f).
DE 34 11 836 A1 discloses a method for controlling the supply of ink and dampening means in planographic printing machines by measuring control marks also printed and subsequently evaluating the measured values, wherein the obtainment of the measured values for determining the ink density and the dampening takes place at the same control marks, signals are obtained which are used to evaluate the dampening and ink density variables, and then the existing dampening and ink density values are calculated and compared with predefined set values within specified tolerance limits by means of a microcomputer, wherein separate control signals are generated for controlling the inking and dampening unit due to the formation of differential signals between set values and actual values.
DE 10 2007 061 397 A1 discloses a printing machine with a device for transferring imaging layers from a transfer film to sheets with at least one application device for an image-wise coating of the sheets with an adhesive and with a coating device downstream thereof for transferring the imaging layers from the transfer film to the sheets, wherein a measuring system based on the sheets is arranged between the application device and the coating device, wherein the opacity of the adhesive layer is measurable with the measuring system and/or wherein control zones and/or measuring strips outside of the print image are detectable with the measuring system.
DE 32 26 144 A1 discloses a method for setting the ink metering on printing machines with an objective presetting of ink metering variables with consideration of machine-influencing variables, wherein, in order to detect the change in the influence of the machine-influencing variables, the paper quality, and the ink properties on the optical density after a presetting of the ink metering, a measuring of the zonal optical density of the printed solid surfaces of a removed printed product is carried out, the comparison between the existing and the required optical density is implemented, and, in the event of a difference in the density values which is outside of a predefined tolerance range, the calculation of the surface portion to be printed and of the resulting ink blade gap is carried out again iteratively, and the setting of the ink blade is executed, and these steps are repeated until the difference between the existing and the required optical density is within the predefined tolerance range.
DE 10 2014 011 151 A1 discloses a method for color control in printing machines having a computing unit by means of detecting color surfaces on a surface to be printed with a colorimeter, wherein the surface to be printed is a printing substrate, wherein the printing substrate is coated with opaque white, wherein the colorimeter detects several color measurements of opaque white, and wherein the computing unit compares the detected color measurements of the opaque white with one another or against a reference color value of the opaque white and stores the deviations determined during the comparison in the computing unit, wherein the printing substrate coated with the opaque white is printed over with color measuring fields, wherein the printed-over color measuring fields are detected by means of the colorimeter, and wherein the computing unit considers the influence of the stored determined deviations during the comparison in order to regulate the coloration of the color measuring values of the color measuring fields underlaid with opaque white with the target color values of the print master.
DE 10 2007 005 018 A1 discloses a method for color control of duplication copies of a printing machine, in which a substrate, which appears to be dark in a standardized color measurement, is printed with at least one printing ink, which is lighter than the substrate, and at least one color value of the printing ink is determined from a measured variable, wherein the color value of the at least one printing ink is regulated with the aid of an established reference value of a color location in the color space, which is brighter than the printing ink.
Coating in production technology is understood to be a primary group of production methods according to DIN 8580 (2003 September edition), which are used to apply an adhering layer comprising formless substance onto the surface of a solid carrier material, which is also designated as the substrate. The corresponding process as well as the applied layer itself are each characterized as coating.
The application of a liquid or a paste, i.e. with high viscosity, or a powder coating material onto a substrate in a machine coating method is described in the following. In this process, after the coating material is applied and optionally after a physical drying and/or a chemical curing on the substrate, the coating material forms a layer which is thin, e.g. in the micrometer range or in the nanometer range, as compared to the material thickness of the substrate. The coating materials also include film-forming coating agents and/or coating materials, which also include, e.g., printing inks, varnishes, inks, or India inks used in the graphics industry or in printing technology and, e.g., coating colors used in the paper industry for surface finishing.
In the preferred embodiment in this case, the substrate is formed as a printing substrate. In this case, the printing substrate consists particularly of paper, paperboard, cardboard, sheet-metal, textiles, glass, ceramics, or a film comprising metal or comprising a plastic. A printing substrate formed, for example, from paper, paperboard, cardboard, film, sheet-metal, or textiles is formed particularly flat as a sheet or as a material web. A printing substrate formed, for example, from sheet metal, plastic, glass, or ceramics may also be formed as a hollow object, e.g. as a container, preferably as a can or as a cup or as a bottle or as a tube. The coating material to be applied to the respective substrate is preferably a colorant, i.e. a color-providing inorganic or organic substance, which may be of natural or synthetic origin and has pigments or at least one dye.
The coating to be implemented according to the invention takes place particularly in an industrial process in a machine processing the respective substrate, preferably in a printing machine or in a paper-processing machine.
The coating material to be applied to the respective substrate may be formed as opaque or varnished. A varnishing coating material may be transparent, i.e. permeable as relates to image or view, or translucent, i.e. partially permeable to light. In contrast, a covering coating material is opaque, i.e. impermeable to light, at least starting at a certain layer thickness applied to the respective substrate. Accordingly, translucence and opacity are reciprocal properties to one another. The opacity is accordingly a measure of the visual opacity or turbidity of translucent materials, i.e. materials and layers permeable to scattered light. In the paper sector, it is customary to indicate the opacity for a respective sheet or page according to ISO 2471. The opacity is defined approximately therein as O=100% minus translucency. A sheet of paper with a translucency of 1% accordingly has an opacity of 99%.
In printing technology, covering printing inks are frequently used for functional or decorative reasons. These printing inks may be, e.g., primary colors such as red, green, and blue, or cyan, magenta, and black, but also opaque white or various metallic colors such as, e.g., gold or silver.
An application of a coating material onto a substrate, which is carried out in an industrial process with an application device, e.g. in a printing machine or in a paper-processing machine, is particularly continually monitored to support the production of a desired quality of the coating during ongoing operation of the printing machine or the paper-processing machine inline and/or online, i.e. during production within and/or outside of the respective machine, normally with a sensing device which functions without contact, e.g. with a sensing device which functions in an optoelectronic measuring method, preferably densitometrically or spectrophotometrically. During this monitoring, it is of particular interest to obtain knowledge about the layer thickness already applied to the respective substrate. The problem is that, during monitoring of a covering coating material in a densitometric or spectrophotometric measuring method, the measured values collected, e.g. for the optical density or a brightness value or a color location of the coating material in question, no longer change starting from a particularly applied layer thickness, that is when an opacity of 100% is reached at the latest. Consequently, there is the risk that the covering coating material will be applied to the respective substrate in an unnecessarily large layer thickness in the industrial process, which is uneconomical at a minimum and additionally makes the respective substrate unnecessarily heavy.
An application device, which is arranged in a printing machine or a paper-processing machine, for automatic application of a coating material onto a substrate preferably has a metering device which is controlled or regulated by a control unit, wherein this metering device influences a respective quantity of the coating material to be applied to the substrate due to the setting, e.g., of a width of at least one discharge opening of a reservoir supplying the coating material and/or of a cycle of a lifter transferring the coating material, wherein the lifter transfers the coating material from a reservoir supplying the lifter to an applicating or transferring roller, and/or of a rotational speed of a roller, particularly of a ductor roller, applying or transferring the coating material.
The object upon which the present invention is based is to obtain a method for setting a layer thickness of a covering coating material to be applied to a respective substrate by an application device, particularly in a printing machine or in a paper-processing machine, with which the layer thickness of the covering coating material applied to the substrate in question is set at a predetermined value, particularly at a value associated with an opacity of 100%, and/or is maintained constantly at this value.
The object is achieved according to the present invention by the provision of the control unit defining the layer thickness of the coating material currently applied to the substrate by the application device in the ongoing machine process, at which layer of thickness the value (D R) of the optical display determined in a grid zone corresponds to the value (D V) of the optical density determined in a solid zone, as the layer thickness of the coating material having an opacity of 100%.
A first solution is particularly that a control unit connected to the sensing device determines a value, particularly as a function of the layer thickness, for the opacity of the layer of coating material applied to the substrate, wherein the control unit sets the layer thickness of the coating material to be applied to at least one further substrate by the application device preferably starting from at least a value of the opacity determined during an accumulating layer structure such that the layer of the coating material to be applied to the at least one further substrate with the application device achieves a value for the opacity previously defined in the control unit preferably in a range of at least 95% to 100% and/or retains said value during ongoing production operation.
A second solution may be that the coating material is applied at various points on the substrate in question by means of the application device in a printing process, wherein, at each of at least one first point on the substrate in question, 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 in question, the coating material is applied over the full area, wherein each first point in question on the substrate in question forms a grid zone and each second point in question on the substrate in question forms a solid zone, wherein a control unit connected to a sensing device determines a respective value for the optical density of the layer of the coating material applied at the points in question on the substrate from data captured by the sensing device at the first and second points on the substrate in question, wherein the control unit defines the layer thickness of the coating material currently applied to the substrate in question by the application device in the ongoing printing process, at which layer 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%.
The advantages achievable with the invention are particularly that the layer thickness of the covering coating material applied to the substrate in question by the application device is set at a value previously defined in the control unit, particularly at a value associated with an opacity in a range of at least 95% to 100% and/or can be maintained constantly at this value. The use of the covering coating material is thereby optimized specifically in an industrial process executed by a printing machine or a paper-processing machine.
Exemplary embodiments of the invention are shown in the figures and described in greater detail in the following.
The following is shown:
The invention is explained without limitation in the following using the example of a printing machine, preferably a rotary printing machine, particularly a sheet-fed rotary printing machine. The printing machine can execute its printing process, e.g., in an offset printing process or in a flexographic printing process or in a screenprinting process or in an inkjet printing process.
The machine unit 01 shown in
The layer thickness of the coating material applied to the substrate with the application device 04 is monitored with a sensing device 12, wherein the sensing device 12 collects measured values inline, i.e. during production, from the covering coating material applied to the respective substrate during an ongoing operation of the printing machine. The sensing device 12, which is arranged within the printing machine, is connected to the respective control unit 06, wherein the control unit 06 determines a value for the opacity of the layer of the coating material applied to the substrate from the measured values previously recorded by the sensing device 12. The signal paths and signal directions from the sensing device 12, via the control unit 06, to the application device 04 are indicated by directional arrows in
The sensing device 12 preferably functions without contact and/or with an optoelectronic measuring method and/or densitometrically or spectrophotometrically. In an especially preferred embodiment, the sensing device 12 is formed as a camera, e.g. as a grayscale camera or as an RGB camera or as a CMYK colorimeter camera, wherein the control unit 06 determines the current value for the opacity of the layer of the coating material applied to the substrate, for example, by means of an evaluation of one or more images of the substrate taken by the camera, i.e. from at least one photographic depiction and/or from the underlying image data. In a further design variant, the sensing device 12 is formed as a reflection light sensor. The control unit 06 sets the layer thickness of the coating material applied to the substrate by the application device 04, particularly starting from at least a value of the opacity determined during an accumulating layer structure, e.g. in a start-up of the printing machine or in a different operating phase of the printing machine, in which the translucency of the layer of the coating material applied to the substrate decreases continually to the point of opacity.
Furthermore, it may be provided to apply the coating material at various points on the sheet 13 in question normally simultaneously in the same printing process by means of the application device 04. The points on the sheet 13 in question, which are different from one another, are, for example, at least two measuring fields 17 different from one another of the same measuring strip 16 or at least two different elements in the same print image 14. It is provided in this case that the coating material is applied at at least one first point on the sheet 13 in question in a grid respectively having several grid points, and the coating material is applied at at least one other second point on the sheet 13 in question over the entire surface. Specifically, this means, for example, that the coating material is applied particularly in at least one of the measuring fields 17 of the measuring strip 16 in question in a grid respectively having several grid points, and the coating material is applied in at least one other measuring field 17 of this measuring strip 16 over the entire surface in the same printing process by means of the application device 04. A first point formed, e.g., as a measuring field 17 on the sheet 13 in question, at which point the coating material is respectively applied in halftone, is also designated as a grid zone, while a second point formed, e.g., as a measuring field 17 on the sheet 13 in question, at which point the coating material is respectively applied over the entire surface, is also designated as a solid zone. The control unit 06 determines a respective value for the optical density of the layer of the coating material applied to the sheet 13 at the points in question from data, e.g. image data, recorded by the sensing device 12 at the respective first and second point on the sheet 13 in question.
The control unit 06 also preferably places the value DR for the optical density, determined from a grid zone, in relation to the respective value DV for the optical density, determined from a solid zone, e.g., by the formation of a ratio DR/DV. Because the optical density is proportional to the quantity of the coating material applied per unit of surface area to the sheet 13 at the points in question on the sheet 13, e.g. in the respective measuring fields 17 of the measuring strip 16, the value DR for the optical density determined in a grid zone in a printing process is less than the value DV for the optical density determined in a solid zone, at least at the start. As the layer thickness of the coating material applied in a grid zone increases, there is an increase in the optical density determined in the grid zone in question, e.g. due to a spreading of the grid points therein and/or optical effects, and the ratio formed from value DR for the optical density determined from a respective grid zone and value DV for the optical density determined from the respective solid zone changes significantly. The control unit 06 then stipulates, particularly when it determines a significant change in the ratio formed from the optical densities, i.e. as a function of this determination, the particularly layer thickness of the coating material currently being applied to the sheet 13 in question by the application device 04, at which layer thickness the value DR for the optical density determined in a grid zone corresponds to the value DV for the optical density determined in a solid zone, as the particular layer thickness of the coating material having an opacity of 100%. The significant change in the ratio formed from the optical densities may be because of the fact that, for example, the value of a ratio formed from these optical densities approximates initially the value 1 in a series of several successive data collections, i.e. determinations of these optical densities, but then stays at least practically unchanged at the value 1 for a preferably previously stipulated number of successive data collections. Thus, the control unit 06 monitors a course or a behavior of this relationship for a significant change, i.e. a change exceeding the permissible tolerance limits, in a series of several successive collections of the optical densities in question. The stipulation relating to the layer thickness of the coating material with an opacity of 100% takes place, for example, in that the control unit 06 stores the currently provided operating data and/or control data of the application device 04 in a storage device 19 in association with the opacity of 100% for the layer thickness of the coating material. Following the determination made, the control unit 06 sets the layer thickness of the coating material, which is to be applied to at least one further substrate, i.e. particularly at least one further sheet 13, by the application device 04, such that the layer of the coating material to be applied to the at least one further substrate with the application device 04 has the opacity of 100% and thus retains it in the subsequent printing process, particularly during ongoing operation of the printing machine or the paper-processing machine.
Well preferred embodiments of a method for setting a layer thickness of a covering coating material to be applied to a substrate by an application device, in accordance with the present invention, have been set forth fully and completely herein above, it will be apparent to one of skill in the art that various changes could be made thereto, without departing from the true spirit and scope of the present invention, which is to be limited only by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2018 121 301.8 | Aug 2018 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/071451 | 8/9/2019 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2020/043463 | 3/5/2020 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20210162734 A1 | Jun 2021 | US |
