Method for calculating parameter for pre-inking printing unit of offset printing press with spot colors

Abstract

The invention relates to a method for calculating a parameter for pre-inking a printing unit of an offset printing press with a spot color, comprising the following steps: a) predetermining the printing unit, the spot color, a substrate to be printed with the spot color, and a specific ink coverage necessary for achieving predetermined color coordinates of the spot color to be achieved on the substrate, b) determining, from at least two different reference spot colors, the number of times that the vibrating roller is in contact with the ink fountain roller, which is necessary for obtaining the specific ink coverage, which has been predetermined in step a), by printing a predetermined spot color onto a predetermined substrate with a predetermined printing unit, each of at least two different reference spot colors has been printed with a different predetermined specific ink coverage onto the substrate that has been predetermined in step a) with a printing unit that has been predetermined in step a).

Description

Technical Field

[0001] The invention relates to a method for calculating parameters for pre-inking a printing unit of an offset printing press with a spot color. Background Art

[0002] The printing unit of the offset printing press includes a plurality of rollers, which transfer the color to be printed on the substrate from the ink tank to the surface of the substrate. More specifically, the ink tank includes an ink key opening, through which the printing ink included in the ink tank is transferred to the first roller of the plurality of rollers, i.e., the ink fountain roller. The amount of printing ink leaving the ink tank per time period can be controlled via the gap of the ink key opening (which is the gap between the ink key opening or the area of ​​the ink key opening and the nearest surface of the ink fountain roller, respectively). The vibrating roller periodically jumps back and forth between the ink fountain roller and another roller, and transfers the printing ink from the ink fountain roller to another roller, such as a friction roller. The frequency at which the vibrating roller periodically jumps back and forth between the two rollers (i.e., the number of times the vibrating roller contacts the ink fountain roller in a time period) controls the amount of printing ink transferred from the ink fountain roller to the surface of the substrate via all downstream rollers. The total (surface) area of ​​all rollers included in the printing unit can reach several square meters, such as about 10 square meters or even more.

[0003] Before using an offset printing press for the first time or after cleaning the press between two different print jobs, the rollers of the printing unit need to be properly moistened with printing ink in a so-called pre-inking process in order to obtain the desired amount of printing ink per area on each part of the substrate surface, which is expressed as specific ink coverage. Since the color intensity or color coordinates of a color depend more or less on the specific ink coverage, obtaining the desired amount of printing ink per area on each part of the substrate surface is essential for the quality of the printing result. This applies in particular to spot colors, i.e. colors printed according to a unique color recipe, which comprises (one or more) pigments in the concentration necessary to achieve the desired color coordinates, if the spot colors are printed with a defined specific ink coverage on the substrate. Such spot colors are used, for example, in packaging and commercial printing. For spot colors, it is necessary to obtain a particularly precise specific coverage of the printing ink on the substrate in order to achieve the predetermined color coordinates, since the spot colors have only small tolerances for the specific ink coverage on the substrate. In other words, if the defined specific ink coverage of the spot color on the substrate is slightly exceeded, or if the defined specific ink coverage of the spot color on the substrate is slightly below the defined specific ink coverage on the substrate, the spot color on the printed substrate does not have the desired color coordinates. However, it takes a considerable time, i.e. up to 100 roller revolutions, until the printing ink is properly distributed over the (surface) area of ​​the roller and with the correct thickness. During this time, a significant amount of the printed substrate is obtained as waste. In addition, the longer the pre-inking time, the longer the printing press cannot be used for printing jobs.

[0004] During pre-inking, the press operator starts pre-inking of the printing unit with arbitrarily selected press parameters (such as an arbitrarily selected gap of the ink key opening of the ink tank, an arbitrarily selected ink fountain roller speed and / or an arbitrarily selected number of times per time period the vibrating roller contacts the ink fountain roller), and then evaluates the specific ink coverage on the substrate obtained. If the specific ink coverage of the substrate is too high or too low, the press operator changes one or more of these selected settings in an attempt to gradually approach the desired specific ink coverage on the substrate. This procedure is time-consuming and produces a lot of printed substrates as waste. For frequently used colors, such as standard colors, such as colors used in CMYK printing, the press operator dictates from his experience that the number of times the vibrating roller contacts the ink fountain roller and other parameters in a time period may be at least very close to the desired specific ink coverage on the substrate surface, which minimizes the time and amount of color required for pre-inking. However, the press operator usually has little or no experience with rarely used spot colors, so more time is needed for pre-inking. This is particularly disadvantageous because spot colors are usually more expensive than colors used for CMYK printing. It would therefore be desirable to have available a method which calculates the most important parameters for pre-inking in order to reduce the time and effort for pre-inking of a printing unit of an offset printing press. Summary of the invention

[0005] In view of the above, it is an object of the present invention to provide a method which allows minimizing the time required for pre-inking a printing unit of an offset printing press with a spot color.

[0006] According to the invention, this object is met by providing a method for calculating parameters for pre-inking a printing unit of an offset printing press with a spot color, the method comprising the following steps: a) predetermining a printing unit, a spot color, a substrate to be printed with the spot color, and a specific ink coverage necessary to achieve predetermined color coordinates of the spot color to be achieved on the substrate, b) determining, from at least two different reference spot colors, a number of times the vibrating roller contacts the ink fountain roller, which number of times the vibrating roller contacts the ink fountain roller is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with a predetermined printing unit, wherein each of the at least two different reference spot colors has been printed onto the substrate that has been predetermined in step a) with a different predetermined specific ink coverage with the printing unit that has been predetermined in step a).

[0007] The solution is based on the surprising finding that using at least two different reference spot colors and printing the at least two different reference spot colors each with different predetermined specific ink coverage onto the substrate to be printed with the printing unit to be used for printing the spot colors allows to easily determine the number of times the vibrating roller contacts the ink fountain roller which is necessary to obtain the specific ink coverage by printing the predetermined spot color onto the substrate with the printing unit, which specific ink coverage of the spot color is necessary to achieve the predetermined color coordinates of the spot color. The inventors have found that there is a mathematical relationship between the area to be inked, the color intensity of the ink in the delivered form (i.e., the color coordinates) and the required ink film thickness and printing unit parameters such as ink fountain roller speed, gap of the inking zone openings and others, which is further described below. In summary, the method according to the invention allows to significantly reduce the time required for pre-inking the printing units of an offset printing press with spot colors.

[0008] According to the invention, specific ink coverage means the ink coverage per area of ​​substrate, i.e. the amount of printed ink in grams per square meter of substrate. Thus, according to the invention, ink coverage means the amount of ink to be printed on the area to be inked depending on the printing subject (as a percentage relative to the total format of the print), in grams, i.e. the amount of ink in grams of the area printed on the substrate.

[0009] The ink coverage can be calculated by multiplying the predetermined specific ink coverage by the total area to be inked of all rollers in the inking unit, optionally adding the area of ​​the dampening roller if the dampening unit is connected to the inking unit during the pre-inking process. Furthermore, the specific ink coverage can be measured by inking a CG1 type proof roller, for example, from IGT Testing Systems (Almere, Netherlands) and measuring the total weight of the proof roller and the applied ink with a precision balance (for example, a 321LT series model from the manufacturer Precisa Gravimetrics AG (Dietikon, Switzerland)), which has a measurement accuracy of at least 0,000 lg. Then, laboratory printing is carried out on a predetermined substrate with the proof roller, and after laboratory printing, the weight of the proof roller is measured with a precision balance. The difference between the total weight of the proof roller and the applied ink before laboratory printing and the weight of the proof roller after laboratory printing is the amount of ink transferred to the substrate in grams. This amount is divided by the total weight in cm 2 The printing area is measured in units of 1 cm. 2 The amount of ink transferred, where this value is multiplied by 10,000 to obtain the amount of ink transferred per square meter.

[0010] Furthermore, according to the present invention, color coordinates mean the position of a color in a color space, such as L-, a-, and b-values ​​of a Lab color space, R-, G-, and B values ​​of an RGB color space, etc. Common reference standards are CIELAB or CIEXYZ color spaces, which are specifically designed to include all colors visible to ordinary people.

[0011] As described above, according to the present invention, the number of times that the vibrating roller contacts the ink fountain roller is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit is determined from at least two different reference spot colors, wherein each of the at least two different reference spot colors has been printed onto the substrate that has been predetermined in step a) with a different predetermined specific ink coverage with the printing unit that has been predetermined in step a). In a trend, the greater the difference between the different predetermined specific ink coverages of the at least two different reference spot colors, the better. For example, when the difference between the predetermined specific ink coverage on one of the at least two different reference spot colors on the substrate and the predetermined specific ink coverage on another of the at least two different reference spot colors on the substrate in step b) is at least 0.3 g / m of the substrate, the difference between the predetermined specific ink coverage on one of the at least two different reference spot colors on the substrate and the predetermined specific ink coverage on the other of the at least two different reference spot colors on the substrate is at least 0.3 g / m 2 , more preferably at least 0.5 g / m 2 , even more preferably at least 0.7 g / m 2 , and more preferably at least 0.8 g / m 2 , and more preferably at least 1.0 g / m 2 and most preferably at least 1.2 g / m 2 The upper limit of the difference between the predetermined specific ink coverage on one of the at least two different reference spot colors on the substrate and the predetermined specific ink coverage on another of the at least two different reference spot colors on the substrate is preferably 3.0 g / m 2 , such that the preferred difference between the predetermined specific ink coverage on one of the at least two different reference spot colors on the substrate and the predetermined specific ink coverage on another of the at least two different reference spot colors on the substrate is 0.3 to 3.0 g / m 2 , more preferably 0.5 to 2.0 g / m 2 , even more preferably 0.7 to 2.0 g / m 2 , still more preferably 0.8 to 2.0 g / m 2 , even more preferably 1.0 to 2.0 g / m 2 And most preferably 1.2 to 2.0 g / m 2. Thus, in case exactly two different reference spot colors are used in step b), it is preferred that the two different reference spot colors are different from each other as described above. If more than two different reference spot colors are used in step b), it is preferred that the predetermined specific ink coverage on one of the at least two different reference spot colors on the substrate differs from the predetermined specific ink coverage on another of the at least two different reference spot colors on the substrate by at least 0.3 g / m 2 of the substrate. 2 , preferably at least 0.5 g / m 2 , more preferably at least 0.7 g / m 2 , even more preferably at least 0.8 g / m 2 , and more preferably at least 1.0 g / m 2 and most preferably at least 1.2 g / m 2 , such as 0.3 to 3.0 g / m 2 , more preferably 0.5 to 2.0 g / m 2 , even more preferably 0.7 to 2.0 g / m 2 , still more preferably 0.8 to 2.0 g / m 2 , even more preferably 1.0 to 2.0 g / m 2 And most preferably 1.2 to 2.0 g / m 2 , wherein the rest of the more than two different reference spot colors may or may not differ from each other by the aforementioned value. More preferably, each of the different reference spot colors is printed onto the substrate at a specific ink coverage that differs from all other different reference spot colors in terms of its specific ink coverage by at least 0.3 g / m 2 of the substrate. 2 , more preferably at least 0.5 g / m 2 , even more preferably at least 0.7 g / m 2 , and more preferably at least 0.8 g / m 2 , and more preferably at least 1.0 g / m 2 and most preferably at least 1.2 g / m 2 , such as 0.3 to 3.0 g / m 2 , more preferably 0.5 to 2.0 g / m 2 , even more preferably 0.7 to 2.0 g / m 2 , still more preferably 0.8 to 2.0 g / m 2 , even more preferably 1.0 to 2.0 g / m 2 And most preferably 1.2 to 2.0 g / m 2 .

[0012] The method according to the invention has no particular restrictions with regard to the number of different reference spot colors used in step b). In a trend, the more different reference spot colors are used in step b), the more precise the result can be expected, but more experimental effort is required. In view of this, it is preferred that two to ten, more preferably two to five, even more preferably two to four, and still more preferably two or three different reference spot colors are used in step b). However, it has been shown during the development of the invention that the use of two different reference spot colors is already sufficient to reliably determine the number of times that the vibrating roller contacts the ink fountain roller, which is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit. Therefore, it is most preferred that exactly two different reference spot colors are used in step b).

[0013] Furthermore, it is preferred that the different reference colors used belong to the same color family as the spot colors used in the subsequent process, ie the reference colors are based on the same binder and solvent and the same drying mechanism.

[0014] According to the invention, at least two different reference spot colors are used in step b). However, the invention is not limited in the kind of difference of the at least two different reference spot colors. For example, the at least two different reference spot colors may differ in the kind of the pigment(s) included in the respective spot colors, but may have the same concentration of the pigment(s). Alternatively, the at least two different reference spot colors may contain the same kind of pigment(s), but may differ in the concentration(s) of the pigment(s). Still alternatively, the at least two different reference spot colors may differ in the kind of the pigment(s) included in the respective spot colors, and differ in the concentration(s) of the pigment(s).

[0015] In view of this, according to a preferred embodiment of the present invention, at least one of the at least two different reference spot colors used in step b) has different color coordinates from at least another one of the at least two different reference spot colors. In this embodiment, it is also preferred that, in case more than two different reference spot colors are used in step b), each of the different reference spot colors has different color coordinates from all other of the different reference spot colors. This can be easily achieved by including in at least one of the at least two different reference spot colors used in step b) at least one pigment that is different from the pigment(s) contained in one or more other reference spot colors of the at least two different reference spot colors.

[0016] According to an alternative preferred embodiment of the invention, at least one of the at least two different reference spot colors used in step b) has the same color coordinates as at least another of the at least two different reference spot colors. If more than two different reference spot colors are used in step b), it is preferred, but not mandatory, that all different reference spot colors have the same color coordinates. This can be easily achieved by including the same pigment(s) in the relevant reference spot colors but in different concentrations in order to meet the requirements of being different reference spot colors.

[0017] According to the invention, the printing unit predetermined in step a) is an offset printing unit, and preferably a sheet-fed offset printing unit or a rotary web offset printing unit.

[0018] In a further development of the idea of ​​the present invention, it is proposed that the printing unit predetermined in step a) includes an inking unit, a groove unit, a plate cylinder, a rubber cylinder and an impression cylinder, wherein the inking unit preferably includes an ink groove, a vibrating roller, an ink fountain roller and one or more ink rollers.

[0019] According to the invention, the number of times the oscillating roller contacts the ink fountain roller necessary to obtain the specific ink coverage already predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with a predetermined printing unit is determined in step b) from at least two different reference spot colors, wherein each of the at least two different reference spot colors has been printed with a different predetermined specific ink coverage onto the substrate already predetermined in step a) with the printing unit already predetermined in step a). Preferably, in addition to the different specific ink coverages of the at least two different reference spot colors, the determination in step b) also takes into account further parameters.

[0020] More specifically, in the first aspect of the present invention, it is preferred that the determination in step b) of the number of times the vibrating roller contacts the ink fountain roller necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit includes the following considerations for each of the at least two different reference spot colors: a) the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking process, b) Ink roller speed, c) the number of times the vibrating roller contacts the ink fountain roller, and d) The gap of the ink key opening of the ink tank.

[0021] Taking any of the aforementioned parameters into account during the determination of step b) means that any of the aforementioned parameters adjusted during the printing of at least two different reference spot colors is used to determine the number of times the vibrating roller contacts the ink fountain roller, which number of times the vibrating roller contacts the ink fountain roller is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing a predetermined spot color onto a predetermined substrate with a predetermined printing unit.

[0022] Furthermore, it is preferred that each of the at least two different reference spot colors has been printed onto the substrate predetermined in step a) with the printing unit predetermined in step a) not only with a different predetermined specific ink coverage but also with at least one further different or identical parameter, such as a different or identical predetermined ink fountain roller speed and / or with a different or identical predetermined gap of the ink key openings of the ink fountain. Thus, preferably, the number of times the oscillating roller contacts the ink fountain roller necessary to obtain the specific ink coverage predetermined in step a) by printing the spot color onto the substrate with the printing unit is determined in step b) from at least two different reference spot colors and preferably from two different reference spot colors, each of the two different reference spot colors having been printed onto the substrate predetermined in step a) with i) a different predetermined specific ink coverage and ii) a different or preferably identical predetermined ink fountain roller speed and / or iii) with a different or preferably identical predetermined gap of the ink key openings of the ink fountain.

[0023] According to a particularly preferred embodiment of the invention, each of the at least two different reference spot colors has been printed with the printing unit already predetermined in step a) not only with a different predetermined specific ink coverage, but also with the same predetermined ink fountain roller speed and with the same predetermined gap of the ink key opening of the ink fountain onto the substrate already predetermined in step a). Therefore, preferably, in step b), the number of times the oscillating roller contacts the ink fountain roller necessary for obtaining the specific ink coverage already predetermined in step a) by printing the spot color onto the substrate with the printing unit is determined, each of the two different reference spot colors has been printed with the printing unit already predetermined in step a) i) with a different predetermined specific ink coverage, ii) with the same predetermined ink fountain roller speed and iii) with the same predetermined ink key opening onto the substrate already predetermined in step a).

[0024] In a further development of the idea of ​​the present invention, it is proposed that the method comprises: i) before printing the at least two different reference spot colors onto the substrate predetermined in step a) with the printing unit predetermined in step a), for each of the at least two different reference spot colors, an ink coverage necessary to achieve a predetermined specific ink coverage to be achieved by printing, a gap of an ink key opening of an ink fountain of an ink fountain of the printing unit to be adjusted during printing, and an ink fountain roller speed to be adjusted during printing, wherein the specific ink coverage predetermined for each of the at least two different reference spot colors is different from one another, ii) printing each of the at least two different reference spot colors with the printing unit predetermined in step a) with a predetermined ink coverage, with a predetermined gap of the ink key opening of the ink fountain of the printing unit, with a predetermined ink fountain roller speed and with an arbitrarily selected number of contacts of the vibrating roller with the ink fountain roller onto the substrate predetermined in step a), iii) determining whether a predetermined specific ink coverage has been achieved on the substrate, wherein if the predetermined specific ink coverage has been achieved on the substrate, the arbitrarily selected number of times the vibrating roller touches the ink fountain roller is saved as the appropriate number of times the vibrating roller touches the ink fountain roller for the corresponding reference spot color, and if the predetermined specific ink coverage has not been achieved on the substrate, repeating step ii) for the relevant reference spot color with one or more other arbitrarily selected numbers of times the vibrating roller touches the ink fountain roller so frequently until the predetermined specific ink coverage is achieved on the substrate, wherein the number of times the vibrating roller touches the ink fountain roller for achieving the predetermined specific ink coverage on the substrate is saved as the appropriate number of times the vibrating roller touches the ink fountain roller, and iv) calculating the number of times the vibrating roller contacts the ink fountain roller to be used in step b), which is necessary for obtaining the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit, based on the appropriate number of times the vibrating roller contacts the ink fountain roller, the predetermined ink coverage, the predetermined gap of the ink key opening of the ink groove, and the predetermined ink fountain roller speed for each of the at least two reference spot colors. The specific ink coverage is necessary for obtaining the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit.

[0025] Furthermore, it is preferred that, in the aforementioned step i), the ink coverage of each of the reference spot colors is calculated as the product (i.e. by multiplication) of the total area to be inked of all rollers in the inking unit and a predetermined specific ink coverage on the reference spot color to be achieved on the substrate, optionally plus the area of ​​the dampening roller if the dampening unit is connected to the inking unit during the pre-inking process.

[0026] According to a further particularly preferred embodiment of the present invention, in step b), for each of the reference spot colors, a coefficient is calculated according to the following formula (1): K n =M n / (B n DS n NVR n ) (1) in: K means coefficient, n is an integer representing the number of associated reference spot colors, M is the amount of spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit (optionally plus the area of ​​the dampening rollers if a dampening unit is connected to the inking unit during a pre-inking process), which expresses the specific grammage per square meter of the corresponding reference color, B is the gap of the ink key opening used during the pre-inking process of the corresponding reference spot color, in m, DS is the ink fountain roller speed used during the pre-inking process of the corresponding reference spot color in m / min, and NVR is the number of times the vibrating roller touches the ink fountain roller.

[0027] Particularly preferably, the method of the aforementioned embodiment further comprises: - calculating the ink coverage of the spot color necessary to achieve the specific ink coverage which in turn is necessary to achieve the color coordinates of the spot color on the substrate which have been predetermined in step a), the color coordinates of the spot color being the product of the total area to be inked of all rollers in the inking unit (optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking process) and the predetermined specific ink coverage to be achieved on the substrate, - predetermining the ink fountain roller speed used during the pre-inking process of the spot color, and - predetermine the gap of the ink key opening used during the pre-inking process of the spot color, The number of times the vibrating roller contacts the ink fountain roller, which is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit, is determined based on the predetermined ink coverage (for example, using a small laboratory printing press for printing and measuring the amount of applied ink), the predetermined ink fountain roller speed (preferably derived from prepress data), the predetermined gap of the predetermined ink key opening, and the coefficients K of at least two reference spot colors. n to calculate.

[0028] In a further development of the idea of ​​the preceding embodiment, it is proposed to use two reference spot colors in step b) of the method, wherein the method further comprises: v) Calculate the coefficient K for the spot color predetermined in step a) according to formula (2): K=(K 1 -K2 ) / (M 1 -M 2 )·M+K 1 -((K 1 -K 2 ) / (M 1 -M 2 ))·M 1 (2) in: K is the coefficient to be calculated for the spot color predetermined in step a), K 1 is the coefficient that has been calculated for the first of the two reference spot colors according to formula (1), K 2 is the coefficient that has been calculated for the second of the two reference spot colors according to formula (1), M is the amount of spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit, which is determined in advance in step a), optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking process, M 1 is the amount of the first reference spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if the dampening unit is connected to the rollers of the inking unit during the pre-inking process, and M 2 is the amount of the second reference spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking process, as well as vi) calculating the number of times the vibrating roller contacts the ink fountain roller, which number of times the vibrating roller contacts the ink fountain roller, is necessary to obtain a specified color coordinate for the spot color predetermined in step a) by printing the spot color onto the substrate with the inking unit at the specific ink coverage that has been predetermined in step a) according to the following formula (3): NVR=M / (K·DS·B) (3), in: NVR is the number of contacts of the vibrating roller with the ink fountain roller which are necessary to obtain the specified color coordinates for the spot color predetermined in step a) by printing the spot color with the specific ink coverage already predetermined in step a) onto the substrate using the inking unit, M is defined as above with respect to formula (2), K is the coefficient calculated in step v) using formula (2), DS is the ink roller speed in meters per minute, and B is the gap of the ink key opening used during the spot color pre-inking process, in m.

[0029] According to an alternative particularly preferred embodiment of the present invention, the number of times the vibrating roller contacts the ink fountain roller necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit is not determined by calculating and using the aforementioned coefficient, but is determined by using a polynomial trend line of the specific ink coverage of each of the reference spot colors relative to the appropriate number of times the vibrating roller contacts the ink fountain roller for each of the reference spot colors that has been determined in the aforementioned step iii). More specifically, in this embodiment, a polynomial trend line of the specific ink coverage of each of the reference spot colors relative to the appropriate number of times the vibrating roller contacts the ink fountain roller for each of the reference spot colors that has been determined in the aforementioned step iii) is determined, wherein the number of times the vibrating roller contacts the ink fountain roller necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit is determined based on the polynomial trend line. For example, before determining the polynomial trend line by using the least squares method, the specific ink coverage of each of the reference spot colors is plotted at the ordinate of the curve graph, and the appropriate number of times the vibrating roller contacts the ink fountain roller for each of the reference spot colors determined in the aforementioned step iii) is plotted at the abscissa of the curve graph.

[0030] The present invention has no particular limitation on the order of the polynomial trend line. However, good results can be obtained when the polynomial trend line is 2 to 5 orders and more preferably 2 to 4 orders. Likewise, it is preferred that the polynomial trend line is determined by using the method of least squares.

[0031] In a further development of the idea of ​​the invention it is suggested to use three to twenty, more preferably five to twenty and most preferably eight to twelve reference spot colors for determining the polynomial trend line.

[0032] Furthermore, it is preferred that the predetermined specific ink coverage of all reference spot colors covers at least 1.2 to 1.6 g / m 2 , more preferably 1.0 to 1.8 g / m 2 And most preferably 0.8 to 2.0 g / m 2 The numerical range of .

[0033] According to a second aspect of the invention, the determination in step b) of the number of times the vibrating roller contacts the ink fountain roller necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit comprises the following considerations for each of the at least two different reference spot colors: a) the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during pre-inking, b) Ink film thickness on the vibrating roller, c) The contact length between the ink fountain roller and the vibrating roller, d) the physical density of the spot color, and d) Ink groove width.

[0034] Taking any of the aforementioned parameters into account during the determination of step b) means that any of the aforementioned parameters adjusted and measured during the printing of at least two different reference spot colors is used to determine the number of times the vibrating roller contacts the ink fountain roller which is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing a predetermined spot color onto a predetermined substrate with a predetermined printing unit.

[0035] Preferably, the number of contacts of the vibrating roller to the ink fountain roller which is necessary to obtain the specific ink coverage already predetermined in step a) by printing the spot color onto the substrate with the printing unit is determined in step b) from at least two different reference spot colors and preferably from at least three different reference spot colors, each of the at least three different reference spot colors having been printed onto the substrate already predetermined in step a) with the printing unit already predetermined in step a) i) with a different predetermined specific ink coverage and ii) with a different or preferably the same predetermined ink film thickness on the vibrating roller and / or iii) with a different or preferably the same predetermined contact length between the ink fountain roller and the vibrating roller and / or iii) with a different or preferably the same predetermined ink groove width.

[0036] In a further development of the idea of ​​the invention, it is suggested that the method comprises: i) before printing the at least two different reference spot colors onto the substrate predetermined in step a) with the printing unit predetermined in step a), for each of the at least two different reference spot colors, the ink coverage necessary to achieve a predetermined specific ink coverage to be achieved by printing, the contact length between the ink fountain roller and the vibrating roller to be adjusted during printing, the ink film thickness on the vibrating roller to be adjusted during printing, and the ink groove width to be adjusted during printing are predetermined, wherein the specific ink coverage predetermined for each of the at least two different reference spot colors is different from one another, ii) for each of the at least two different reference spot colors, calculating the number of contacts of the vibrating roller to the ink fountain roller required to ink the entire area of ​​the printing unit, iii) printing each of the at least two different reference spot colors on the substrate predetermined in step a) with a predetermined ink coverage, with a predetermined contact length between the ink fountain roller and the vibrating roller, with a predetermined ink film thickness on the vibrating roller, with a predetermined ink groove width and with an arbitrarily selected number of contacts of the vibrating roller to the ink fountain roller using the printing unit predetermined in step a), iv) determining whether a predetermined specific ink coverage has been achieved on the substrate, wherein if the predetermined specific ink coverage has been achieved on the substrate, the arbitrarily selected number of times the vibrating roller touches the ink fountain roller is saved as the appropriate number of times the vibrating roller touches the ink fountain roller for the corresponding reference spot color, and if the predetermined specific ink coverage has not been achieved on the substrate, repeating step ii) for the relevant reference spot color with one or more other arbitrarily selected numbers of times the vibrating roller touches the ink fountain roller so frequently until the predetermined specific ink coverage is achieved on the substrate, wherein the number of times the vibrating roller touches the ink fountain roller for achieving the predetermined specific ink coverage on the substrate is saved as the appropriate number of times the vibrating roller touches the ink fountain roller, v) determining, preferably by using a least squares method, a polynomial trend line of the appropriate number of times the vibrating roller contacts the ink fountain roller determined in step iv) relative to the number of times the vibrating roller contacts the ink fountain roller calculated in step ii) for at least two different reference spot colors, and vi) for the spot color already predetermined in step a), calculating the number of contacts of the vibrating roller to the ink fountain roller required to ink the entire area of ​​the printing unit, and therefrom calculating the number of contacts of the vibrating roller to the ink fountain roller necessary to obtain the specific ink coverage already predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit using the polynomial trend line already predetermined in step v).

[0037] For each of the at least two different reference spot colors, the calculation of the number of times the vibrating roller touches the ink fountain roller required to ink the entire area of ​​the printing unit in step ii) can be performed as follows. For example, the required volume (V) of the corresponding reference spot color for achieving the correct ink saturation and thus the color target can be calculated by multiplying the total area to be inked of all rollers in the inking unit of the printing press (without the area of ​​the dampening roller, because the dampening unit is not connected to the inking unit during the pre-inking process) by the specific ink coverage predetermined for the corresponding reference spot color. In addition, the amount (A) of the corresponding reference spot color transferred during one contact of the ink fountain roller and the vibrating roller can be calculated, for example, by multiplying the predetermined contact length between the ink fountain roller and the vibrating roller by the predetermined ink film thickness on the vibrating roller and by the predetermined ink groove width and by the physical density of the corresponding reference spot color. Then, by dividing the above-mentioned volume (V) by the amount (A), the number of times the vibrating roller touches the ink fountain roller required to ink the entire area of ​​the printing unit in step ii) can be easily calculated.

[0038] Since the ink transfer between the individual rollers in the inking unit is usually not a theoretically possible value, but less in practice, it is preferred to determine a correction factor (which takes into account the difference between the theoretically achievable and actually achieved ink transfer amounts between the rollers in the printing unit) and use this correction factor for determining the necessary actual number of vibrating roller contacts to the ink fountain roller from the above calculated number of vibrating roller contacts to the ink fountain roller required for inking the entire area of ​​the printing unit in step ii). Preferably, as a correction factor, a polynomial trend line of the specific ink coverage of each of the reference spot colors relative to the appropriate number of vibrating roller contacts to the ink fountain roller for each of the reference spot colors is determined, as illustrated in more detail in Example 3 that follows. Then, the number of vibrating roller contacts to the ink fountain roller that is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing a predetermined spot color onto a predetermined substrate with a predetermined printing unit can be easily determined from the polynomial trend line. That is, the theoretical number of times the vibrating roller contacts the ink fountain roller required for inking the entire area of ​​the printing unit in step ii) can be calculated for the predetermined spot color, as described above for the reference spot color, and then the number of times the vibrating roller contacts the ink fountain roller that is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit is determined from this theoretical number of times the vibrating roller contacts the ink fountain roller using a polynomial trend line.

[0039] Good results are particularly obtained when using the method of least squares to determine a polynomial trend line, wherein the polynomial trend line is preferably of 2nd to 5th order and more preferably of 2nd to 4th order.

[0040] According to a further preferred embodiment of the present invention, in the aforementioned embodiment, three to twenty, more preferably five to twenty and most preferably eight to twelve reference spot colors are used to determine the polynomial trend line, wherein preferably the predetermined specific ink coverage of all reference spot colors covers at least 1.2 to 1.6 g / m 2 , more preferably 1.0 to 1.8 g / m 2 And most preferably 0.8 to 2.0 g / m 2 The numerical range of .

[0041] Other ink-related measurable variables that may have an impact on the pre-inking process and therefore may be used in the calculations are the L value of the ink (light / dark), rheological parameters such as viscosity and viscosity, the proportion of non-coloring components in the ink (transparent white), pigment type and amount.

[0042] Measurable parameters relevant to the printing press are the temperature in the printing unit (which influences the rheological properties and transfer behavior of the ink from roller to roller in the printing unit), the contact length between the ink fountain roller and the vibrating roller during one contact, the size of the gap between the individual rollers in the printing unit, the ink gutter width, different or equal openings of individual areas in the ink fountain, etc. These parameters may also be used in the calculation.

[0043] Additionally, substrate-related properties such as absorbency, surface smoothness and texture, substrate whiteness or opacity, and surface energy can affect the accurate achievement of color targets. If substrates are grouped together, such as coated, uncoated, recycled, etc., and calculators are generated for each group and ink type, the effects of the substrate can be taken into account.

[0044] Other printing press related parameters that are difficult or impossible to measure are roller adjustment, maintenance condition of the printing unit, roller flatness, roller type, condition and quality of polymer roller coating and type and quality of printing plates used.

[0045] Even if the pre-inking process is run substantially without fountain solution, the emulsification behavior of the ink may have an influence on the ink tone or ink density obtained after printing. Therefore, the amount of fountain solution and its components may also affect the printing result.

[0046] Three specific embodiments have been described above for determining the number of times the vibrating roller contacts the ink fountain roller necessary to obtain the specific ink coverage that has been predetermined in step a) by printing a predetermined spot color onto a predetermined substrate with a predetermined printing unit. In one embodiment, parameters such as the ink fountain roller speed, the number of times the vibrating roller contacts the ink fountain roller, and the gap of the ink key opening of the ink fountain are predetermined for a reference spot color, and a coefficient is determined, according to which the number of times the vibrating roller contacts the ink fountain roller necessary to obtain the specific ink coverage that has been predetermined in step a) by printing a predetermined spot color onto a predetermined substrate with a predetermined printing unit is calculated. In another embodiment, parameters such as ink fountain roller speed, the number of times the vibrating roller contacts the ink fountain roller, and the gap of the ink key opening of the ink fountain are predetermined for the reference spot colors, and the number of times the vibrating roller contacts the ink fountain roller necessary for obtaining the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit is calculated using a polynomial trend line of the specific ink coverage of each of the reference spot colors relative to the appropriate number of times the vibrating roller contacts the ink fountain roller for each of the reference spot colors. In yet another embodiment, other parameters such as the ink film thickness on the vibrating roller, the contact length between the ink fountain roller and the vibrating roller, the physical density of the spot color, and the ink fountain width are predetermined for the reference spot color, and the number of times the vibrating roller contacts the ink fountain roller necessary for obtaining the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate with the predetermined printing unit is calculated using a polynomial trend line of the appropriate number of times the vibrating roller contacts the ink fountain roller from the printing attempt relative to the calculated number of times the vibrating roller contacts the ink fountain roller. The calculator can be programmed to automatically perform the corresponding calculations described above. In addition, it is possible to connect the calculator to the control system of the printing press directly or via an interface. Possibly as a link to the control system of the printing press, the calculator can also be linked to the prepress process, in which the corresponding parameters such as the speed of the printing plate and the ink fountain roller are calculated. Alternatively, the calculator can be linked in an analog or digital manner, for example, directly or via an interface with ink formulation software or a system for digital color communication (HDCC of hubergroup Germany GmbH), in which the specific ink coverage of commercial printing inks has been recorded or the specific ink coverage of newly generated printing inks is also recorded. In addition, the calculator can also be linked to other databases such as SAP, from which the ink-specific data required for calculating the vibration roller contact can also be accessed. By taking into account other influencing variables such as substrate type, fountain solution type, printing press type and ink series, the calculator can be expanded to a general calculator. The system for optimizing ink supply can use a mobile device, be linked to a database, be set as an application, and can be used via various terminals. If the calculated ink fountain roller and vibration roller contact does not produce the desired printing result, the calculator can have a built-in control step.This can be used as a tool for early detection of maintenance needs or regulation problems.

[0047] The invention is not particularly limited with regard to the type of substrate. Good results are particularly obtained when the substrate predetermined in step a) is a foil, a film, a coated or uncoated paper, a metal substrate, a metallized substrate, a laminate or a paperboard.

[0048] The present invention is also particularly suitable for physically and / or chemically drying offset inks or inks with a combined drying mechanism (e.g., penetration drying offset spot color inks, evaporation drying offset spot color inks, oxidation drying offset spot color inks) as well as radiation curing offset spot color inks, free radical curing and / or cationic curing and / or other NCO / OH curing reactions and inks with a combined drying mechanism.

[0049] The invention is subsequently described with the aid of the accompanying drawings which are illustrative and non-limiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A printing unit of an offset printing press suitable for use in the method of the invention is shown schematically.

[0051] Figure 2 A 2nd order polynomial trend line is shown of the number of times the vibrating roller of each of the reference spot colors 1 to 3, which has been determined in the corresponding printing experiments described in Example 3, contact the ink fountain roller relative to the calculated number of times the vibrating roller of each of the reference spot colors 1 to 3 contact the ink fountain roller on the abscissa. DETAILED DESCRIPTION

[0052] The printing unit 10 of an offset printing press suitable for use in the method of the present invention, as shown in a schematic side view, comprises a plate cylinder 12, a blanket cylinder 14 and an impression cylinder 16, wherein a substrate 18 to be printed with a spot color is guided through the blanket cylinder 14 and the impression cylinder 16. Printing ink is transferred from the plate cylinder 12 to the blanket cylinder 14 and further to one surface of the substrate 18 during the pre-inking process and the subsequent printing process, while the impression cylinder 16 serves as a supporting cylinder. In addition, the printing unit comprises an ink fountain 20, an ink fountain roller 22, a vibrating roller 24 and further rollers, and during the pre-inking process and the subsequent printing process, printing ink is transferred from the ink fountain 20 via the ink fountain roller 22, then via the vibrating roller 24 and then via further rollers to the blanket cylinder 14 and from there to the surface of the substrate 18. The ink tank 20 comprises an ink key opening (not shown) with a variable adjustable gap, through which the ink is transferred to the surface of the ink fountain roller, and through which the amount of printing ink transferred to the ink fountain roller 20 per time period is controlled. Further rollers are friction rollers 26, 26', 26", friction rollers 28, 28', 28", weighted rollers 30, 30', 30", friction rollers 32, 32', 32", color coating rollers 34, 34', 34", 34"', 34"" and rollers belonging to the tank unit, namely the tank bridge roller 36, the tank coating roller 38, the transfer roller 40, the tank metering roller 42 and the ink leveling roller 44. There is a large gap between the ink fountain roller 22 and the friction roller 26, so that the vibration roller 24 does not contact each of its adjacent ink fountain roller 22 and friction roller 26 at the same time, but the vibration roller 24 periodically jumps back and forth between the two elements, so that the vibration roller 24 periodically contacts the ink fountain roller 22 or the friction roller 26, as indicated by arrow 46.

[0053] Subsequently, the invention is described by means of illustrative and non-limiting examples.

[0054] Example 1

[0055] (Spot colors, printing presses, and press settings)

[0056] The following colors, presses, and parameters were used or adjusted:

[0057] Printing Press : KBA PA 145, AG (Radebeul, Germany).

[0058] fountain solution : SC042-73, 4% in completely deionized water, with 0.7% Magnesite hardened, blended fountain solution with 700μs / cm 2conductivity, a water hardness of 12° German hardness, a pH value of 5.7 at 7.5°C and an alcohol content of 4.5%.

[0059] The total area to be inked of all rollers in the inking unit of the printing press (the area of ​​the dampening roller, because the pre-inking process The dampening unit is not connected to the inking unit during the process) :9.25m 2

[0060] Printing Format : 102×142cm

[0061] Substrate : Serviliner Material thickness: 250g / m 2

[0062] Spot color for example 1 : MGA Natura 660613P, hubergroup Deutschland GmbH (Celle, Germany).

[0063] Ink coverage of spot color of Example 1 : 1.5g / m 2

[0064] Ink roller speed for spot color of Example 1 : 26%

[0065] This percentage number has been calculated or generated respectively via the ink coverage area calculation in the prepress process. This information has been transmitted to the printing press using, for example, the cip3 data format and has been used for both printing and pre-inking. Cip3 means "integrated collaboration of prepress, printing and postpress". This format is the current standard for transmitting order-related data in the printing process.

[0066] The gap of the ink key opening of the ink tank of the spot color of Example 1 : 60%

[0067] Reference spot color 1 : 679540P MGA Natura Grün MOPS intense, hubergroup Deutschland GmbH (Celle, Germany).

[0068] Reference spot color 1 ink coverage : 1.2g / m 2

[0069] Refer to the ink roller speed of spot color 1 : 9%

[0070] This percentage number has been calculated or generated respectively via the ink coverage area calculation in the prepress process. This information has been transmitted to the printing press using, for example, the cip3 data format and has been used for both printing and pre-inking. This format is the current standard for transmitting order-related data in the printing process.

[0071] Refer to the gap of the ink key opening of the ink tank of spot color 1 : 60%

[0072] Reference spot color 2 : 679539P MGA Natura Grün MOPS low, hubergroup Deutschland GmbH (Celle, Germany).

[0073] Reference spot color 2 ink coverage : 1.8g / m 2

[0074] Ink roller speed for spot color 2 : 9%, generated as described above.

[0075] Refer to the gap of the ink key opening of the ink tank of spot color 2 : 60%

[0076] (For reference spot colors 1 and 2, recalculate the ink roller speed and the gap of the ink key opening of the ink slot)

[0077] The ink fountain roller speed of the printing units of the printing press must be adjusted in % and therefore needs to be recalculated to a value in m / min. Therefore, the printing press has been operated with an ink fountain roller speed of 9% (which was the setting of the printing press during the pre-inking process) and the speed of the ink fountain roller has been measured in m / min with a digital handheld tachometer. From this, the following ink fountain roller speeds are obtained: Refer to the ink roller speed of spot color 1 : 2.72 m / min Refer to the ink roller speed of spot color 2 : 2.72 m / min

[0078] Furthermore, the gaps of the ink key openings of the ink tanks of 60% reference spot colors 1 and 2 (which are the settings of the printing press during the pre-inking process) have been determined in mm by measuring the gaps of the ink key openings of the ink tanks with a feeler gauge. Thus, the following gaps of the ink key openings of the ink tanks were obtained: Refer to the gap of the ink key opening of the ink tank of spot color 1 :0.15mm Refer to the gap of the ink key opening of the ink tank of spot color 2 :0.15mm

[0079] (Refer to the calculation of ink coverage of spot colors 1 and 2)

[0080] The ink coverage of reference spot colors 1 and 2 has been calculated according to the following formula: M n =F·SM n , in: n is an integer of 1 or 2, representing the number of the reference spot color M n It refers to the ink coverage of the spot color. F is the total area to be inked of all rollers in the inking unit of the printing press, i.e. 9.25 m2 as mentioned above. 2 , and SM n is the specific ink coverage of the reference spot color, i.e. 1.2g / m 2 and 1.8g / m2 of reference spot color 2 2 .

[0081] Thus, the following ink coverage was obtained: Reference spot color 1 ink coverage :11.10g Refer to the ink coverage of spot color 2 :16.65g

[0082] (Determine the number of times the vibrating roller touches the ink fountain roller for reference spot colors 1 and 2)

[0083] Pre-inking of the printing unit of the above-mentioned printing press on the above-mentioned substrate has been carried out in two separate sets of experiments with each of the reference spot colors 1 and 2 using the above-mentioned ink fountain roller speeds and the above-mentioned gaps of the ink key openings of the ink trough. Each set of experiments started with 22 contacts of the vibrating roller with the ink fountain roller, and after the pre-inking, the obtained specific ink coverage of the corresponding reference spot color on the substrate has been measured. In the case of 22 contacts of the vibrating roller with the ink fountain roller, the obtained specific ink coverage was too high, and therefore the number of contacts of the vibrating roller with the ink fountain roller has been reduced in the further printing of the two reference spot colors until the predetermined above-mentioned specific ink coverage of 1.2 g / m for the reference spot color 1 was obtained. 2 and 1.8g / m2 of reference spot color 2 2 Thus, the following number of times the vibrating roller contacts the ink fountain roller is obtained: Refer to the number of times the vibration roller of spot color 1 touches the ink fountain roller :19 Refer to the number of times the vibration roller of spot color 1 touches the ink fountain roller :16

[0084] (Calculate the coefficients for reference spot colors 1 and 2)

[0085] Using the parameters mentioned above, the coefficients for reference spot colors 1 and 2 are calculated using formula (1).

[0086] K1=11.10g / (1.5·10 -4 m·2.72m / min·19)=1432(g·m 2 ) / min.

[0087] K2=16.65g / (1.5·10 -4 m.2.72m / min·16)=2551(g·m 2 ) / min.

[0088] (Calculation of coefficients for spot colors of Example 1)

[0089] The ink roller speed of the spot color of Example 1 was 26% (this percentage number has been calculated / generated via the ink coverage area calculation in the prepress department; this information has been transferred to the printing press using the cip3 data format and has been used for both printing and pre-inking). The ink roller speed in meters per minute was measured with a digital handheld tachometer. From this, the following ink roller speeds were obtained: Ink roller speed for spot color of Example 1 : 6.64 m / min.

[0090] Using the ink fountain roller speed of the spot color of Example 1, the coefficient of the spot color of Example 1 can be calculated according to the following formula (2): K=(K 1 -K 2 ) / (M 1 -M 2 )·M+K 1 -((K 1 -K 2 ) / (M 1 -M 2 ))·M 1 (2) Right now K=(1432-2551) / (11,1-16,65)*13,875+1432-((1432-2551) / 11,1-16,65))*11,1=1992(g·m 2 ) / min.

[0091] (Count the number of times the vibration roller touches the ink fountain roller for the spot color of Example 1)

[0092] The ink coverage of the spot color of Example 1 can be calculated according to the above-mentioned formula M: n =F·SM n =9.25·1.5g / m 2 = 13.875g calculated.

[0093] Using the coefficient K calculated above, K = 1992 (g·m 2 ) / min, the number of times the vibration roller contacts the ink fountain roller for the spot color of Example 1 can be calculated according to the following formula (3): NVR=M / (K·DS·B) (3) Right now NVR=13.875g / (1992(g·min / m 2 )·6.64m / min·1.5*10 -4 m=7.

[0094] In summary, the desired setting of the number of contacts of the vibrating roller (ie, between the ink fountain roller and the vibrating roller) in the printing unit of the printing press is 7.

[0095] Example 2

[0096] Use the same press, reference spot color, substrate, and settings as in Example 1, except for the following: Spot Color for Example 2 : MGA Natura 675056P, hubergroup Deutschland GmbH (Celle, Germany).

[0097] Ink coverage of spot color of Example 1 : 0.8g / m 2

[0098] Ink roller speed for spot color of Example 1 : 36%

[0099] The gap of the ink key opening of the ink tank of the spot color of Example 1 : 60%

[0100] The ink fountain roller speed of the spot color of Example 2 in meters / minute was measured at 36% (this percentage number has been calculated or generated via the ink coverage area calculation in the prepress process, respectively. This information has been transmitted to the printing press using, for example, the cip3 data format, and has been used for both printing and pre-inking) with a digital handheld tachometer. From this, the following ink fountain roller speed was obtained: Ink roller speed for spot color of Example 2 : 8.95 m / min.

[0101] Using the ink fountain roller speed of the spot color of Example 2, the coefficient of the ink fountain roller speed of the spot color of Example 2 can be calculated according to the following formula (2): K=(K 1 -K 2 ) / (M 1 -M 2 )·M+K 1 -((K 1 -K 2 ) / (M 1 -M 2 ))·M 1 (2) Right now K=(1432-2551) / (11,1-16,65)*7,4+1432-((1432-2551) / 11,1-16,65))*11,1=686(g·m 2 ) / min.

[0102] The ink coverage of the spot color of Example 2 can be calculated according to the above-mentioned formula M: n =F·SM n=9.25·0.8g / m 2 =7.4g calculation.

[0103] Using the coefficient K calculated above, K = 686 (g·m 2 ) / min, the number of times the vibration roller contacts the ink fountain roller for the spot color of Example 2 can be calculated according to the following formula (3): NVR=M / (K·DS·B) (3) Right now NVR=7.4g / (686(g.min / m 2 )·8.95m / min·1.5*10 -4 m=0.8, rounded to 1.

[0104] In summary, the desired setting of the number of contacts of the vibrating roller (ie, between the ink fountain roller and the vibrating roller) in the printing unit of the printing press is 1.

[0105] Example 3

[0106] The same printing press and fountain solution as in Example 1 were used.

[0107] The total area to be inked (F) of all rollers in the inking unit of the printing press (without the area of ​​the dampening roller, because the pre- The dampening unit is not connected to the inking unit during the inking process) :8.89m 2

[0108] Printing Format : 102×142cm

[0109] Substrate : Serviliner Material thickness: 250g / m 2

[0110] Three reference spot colors were used.

[0111] Reference spot color 1 : VG00113293, Pantone 386C MGA Natura, hubergroup Deutschland GmbH (Celle, Germany).

[0112] Reference spot color 1 ink coverage (SM 1 ): 0.9g / m 2

[0113] Density of reference spot color 1 (ρ 1 ): 1.009g / cm 3 .

[0114] The contact length (CL) between the ink fountain roller and the vibration roller is 4.2 cm.

[0115] Ink film thickness on the vibration roller (IT): 0.0075 cm.

[0116] Ink trough width (IFW): 145cm.

[0117] For all experiments, the ink roller speed was the same.

[0118] The volume of reference spot color 1 required to achieve the correct ink saturation to achieve the color target is calculated according to the following formula: V 1 =F·SM 1 =8.89m 2 0.9g / m 2 =8.001g.

[0119] The amount (IA) of the reference spot color 1 transferred during one contact of the ink fountain roller with the vibrating roller is calculated according to the following formula: IA = CL·IT·IFW·ρ 1 =4.2cm·0.0075cm·145cm·1.009g / cm 3 =4.608g.

[0120] Therefore, the number of times the vibrating roller contacts the ink fountain roller required to ink the entire inking area is V. 1 / IA=8.001g / 4.608g=1.7361, rounded to 2.

[0121] Reference spot color 2 :VG00032589 Pantone 2411C MGA Natura, hubergroup Deutschland GmbH (Celle, Germany).

[0122] Reference spot color 2 ink coverage (SM 2 ) : 1.4g / m 2

[0123] Density of reference spot color 2 (ρ 2 ) : 1.08g / cm 3 .

[0124] The contact length (CL) between the ink fountain roller and the vibration roller is 4.2 cm.

[0125] Ink film thickness on the vibration roller (IT): 0.0075 cm.

[0126] Ink trough width (IFW): 145cm.

[0127] The volume of reference spot color 2 required to achieve the correct ink saturation to achieve the color target is calculated according to the following formula: V 2 =F·SM 2 =8.89m 2 1.4g / m 2 =12.446g.

[0128] The amount (IA) of the reference spot color 2 transferred during one contact of the ink fountain roller with the vibrating roller is calculated according to the following formula: IA = CL·IT·IFW·ρ 2 =4.2cm·0.0075cm·145cm·1.08g / cm 3 =4.9329g.

[0129] Therefore, the number of times the vibrating roller contacts the ink fountain roller required to ink the entire inking area is V. 2 / IA=12.446 / 4.9329g=2.5231, rounded to 3.

[0130] Reference spot color 3 : VG00069398, Pantone 391C MGA Natura, hubergroup Deutschland GmbH (Celle, Germany).

[0131] Reference spot color 3 ink coverage (SM 1 ) : 1.8g / m 2

[0132] Density of reference spot color 3 (ρ 3 ) :1.074g / cm 3 .

[0133] The contact length (CL) between the ink fountain roller and the vibration roller is 4.2 cm.

[0134] Ink film thickness on the vibration roller (IT): 0.0075 cm.

[0135] Ink trough width (IFW): 145cm.

[0136] The volume of reference spot color 3 required to achieve the correct ink saturation to achieve the color target is calculated according to the following formula: V 3 =F·SM 3 =8.89m 2 1.8g / m 2 =16.002g.

[0137] The amount (IA) of the reference spot color 3 transferred during one contact of the ink fountain roller with the vibrating roller is calculated according to the following formula: IA = CL·IT·IFW·ρ 3 =4.2cm·0.0075cm·145cm·1.074g / cm 3 =4.9055g.

[0138] Therefore, the number of times the vibrating roller contacts the ink fountain roller required to ink the entire inking area is V. 3 / IA=16.002g / 4.9055g=3.2621, rounded to 3.

[0139] Since the ink transfer between the individual rollers in the inking unit is generally not a theoretically possible value, but less in practice, the correction factor is determined by measuring the number of times the vibrating roller touches the ink fountain roller, which is necessary for inking the entire area to be inked by printing the reference spot color 1 onto the substrate. More specifically, pre-inking of the printing unit of the above-mentioned printing press onto the above-mentioned substrate has been performed with each of the reference spot colors 1 to 3 in three separate sets of experiments, using the above-mentioned contact length, the ink film thickness on the vibrating roller and other parameters. Each set of experiments started with a number of 22 vibrating roller touches to the ink fountain roller, and after the pre-inking, the obtained specific ink coverage of the corresponding reference spot color on the substrate has been measured indirectly by measuring the color intensity. In the case where the number of times the vibration roller touches the ink fountain roller is 22, the specific ink coverage obtained is too high, and therefore the number of times the vibration roller touches the ink fountain roller has been reduced in the further printing of the two reference spot colors until the predetermined above-mentioned specific ink coverage, i.e. 0.9 g / m2 for the reference spot color 1, is obtained by achieving the desired color strength. 2 , refer to spot color 2 1.4g / m 2 and 1.8g / m2 of reference spot color 3 2 Thus, the following number of times the vibrating roller contacts the ink fountain roller is obtained, which is significantly higher than the number calculated above:

[0140] Considering these values, Figure 2 The 2nd order polynomial trend line shown in has determined the relationship between the number of times the vibration roller of each of the reference spot colors 1 to 3 has touched the ink fountain roller relative to the calculated number of times the vibration roller of each of the reference spot colors 1 to 3 has touched the ink fountain roller, which has been determined in the corresponding printing experiment. In other words, Figure 2 The ordinate of the graph shows the number of times the vibration roller of each of the reference spot colors 1 to 3 has touched the ink fountain roller, which has been determined in the corresponding printing experiment, and the abscissa shows the calculated number of times the vibration roller of each of the reference spot colors 1 to 3 has touched the ink fountain roller. The formula of the polynomial trend line is: Y = -1.4493·x 2 +13.797·x-11.585.

[0141] Using this polynomial trend line, for Example 3 The number of times the vibrating roller contacts the ink fountain roller necessary to print the predetermined spot color onto the predetermined substrate and obtain a predetermined specific ink coverage is determined as follows: Spot color for example 3:VG00073407 Pantone 2186C, MGA Natura, hubergroup Deutschland GmbH (Celle, Germany).

[0142] Specific ink coverage (SM) of the spot color of Example 3 : 1.2g / m 2

[0143] Density of spot color of Example 3 (ρ) : 1.08g / cm 3 .

[0144] The contact length (CL) between the ink fountain roller and the vibration roller is 4.2 cm.

[0145] Ink film thickness on the vibration roller (IT): 0.0075 cm.

[0146] Ink trough width (IFW): 145cm.

[0147] To achieve the correct ink saturation and thus achieve the color goals required Example 3 The volume of spot colors is calculated according to the following formula: V=F·SM=8.89m 2 1.2g / m 2 =10.668g.

[0148] The ink is transferred during the first contact between the ink fountain roller and the vibrating roller. Example 3 The amount of spot color is calculated according to the following formula: IA = CL·IT·IFW·ρ = 4.2cm·0.0075cm·145cm·1.08g / cm 3 =4.9329g.

[0149] Therefore, the number of times the vibration roller contacts the ink fountain roller required to ink the entire inking area is V 1 / IA=10.668g / 4.9329g=2.1626.

[0150] Considering the polynomial trend line above, the actual number of vibrating rollers taking into account the correction factor is: Y=-1.4493·(2.1418) 2 +13.797·2.1418-11.585=11.32, rounded to 11.

[0151] Thus, by simply using the aforementioned polynomial trend line that only needs to be generated once with a set of reference spot colors, the number of times the vibrating roller contacts the ink fountain roller necessary to print the spot colors of Example 3 and any other spot colors can be reliably obtained without the need to print the corresponding spot colors of Example 1 onto the substrate.

[0152] Reference numerals 10 printing units 12 Plate Cylinders 14 Blanket Cylinder 16Impression roller 18 Substrate to be printed with spot color 20 ink tanks 22 ink roller 24 Vibrating roller 26,26',26" Friction Roller 28,28',28" Friction Roller 30,30',30" counterweight roller 32,32',32" friction roller 34,34',34”,34”’,34””painting roller 36 groove bridge roller 38 groove coating roller 40 transfer roller 42 groove metering roller 44 ink roller 46 arrows.

Claims

1. A method for calculating parameters for pre-inking a printing unit (10) of an offset printing press with a spot color, comprising the following steps: a) predetermining a printing unit (10), a spot color, a substrate (18) to be printed with the spot color, and a specific ink coverage necessary to achieve predetermined color coordinates of the spot color to be achieved on the substrate (18), b) determining the number of times the vibration roller contacts the ink fountain roller (22) from at least two different reference spot colors, the number of times the vibration roller contacts the ink fountain roller (22) being necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate (18) with the predetermined printing unit (10), wherein each of the at least two different reference spot colors has been printed onto the substrate (18) that has been predetermined in step a) with a different predetermined specific ink coverage with the printing unit (10) that has been predetermined in step a).

2. The method according to claim 1, wherein: In step b), the difference between the predetermined specific ink coverage of one of the at least two different reference spot colors on the substrate (18) and the predetermined specific ink coverage of another of the at least two different reference spot colors on the substrate (18) is at least 0.3 g / m2 of the substrate (18). 2 , preferably at least 0.5 g / m 2 , more preferably at least 0.7 g / m 2 , even more preferably at least 0.8 g / m 2 , and more preferably at least 1.0 g / m 2 and most preferably at least 1.2 g / m 2 .

3. The method according to claim 1 or 2, wherein: Two to ten, preferably two to five, more preferably two to four, still more preferably two to three and most preferably two different reference spot colors are used in step b).

4. A method according to any one of the preceding claims, wherein: All reference spot colors used in step b) have the same color coordinates.

5. A method according to any one of the preceding claims, wherein: The printing unit (10) predetermined in step a) includes an inking unit, a groove unit, a plate cylinder (12), a rubber cloth cylinder (14) and an impression cylinder (16), wherein the inking unit preferably includes an ink groove (20), a vibrating roller (24), an ink fountain roller (22) and one or more ink rollers.

6. The method according to claim 5, wherein: The determination in step b) of the number of times the vibrating roller contacts the ink fountain roller (22) necessary to obtain the specific ink coverage already predetermined in step a) by printing the predetermined spot color onto the predetermined substrate (18) with the predetermined printing unit (10) comprises the following considerations for each of the at least two different reference spot colors: a) the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking, b) the speed of the ink fountain roller (22), c) the number of times the vibrating roller contacts the ink fountain roller (22), and d) a gap between the ink key openings of the ink tank (20).

7. The method according to claim 5 or 6, wherein: In step b), the number of times the oscillating roller contacts the ink fountain roller (22) necessary to obtain the specific ink coverage already predetermined in step a) by printing the spot color onto the substrate (18) with the printing unit (10) is determined from at least two different reference spot colors and preferably from two different reference spot colors, each of which has been printed onto the substrate (18) already predetermined in step a) with a different predetermined specific ink coverage, at the same predetermined ink fountain roller (22) speed and at the same predetermined ink key opening of the ink fountain (20) with the printing unit (10) already predetermined in step a).

8. The method according to any one of claims 5 to 7, comprising: i) before printing the at least two different reference spot colors onto the substrate (18) already predetermined in step a) with the printing unit (10) already predetermined in step a), predetermining for each of the at least two different reference spot colors an ink coverage necessary to achieve a predetermined specific ink coverage to be achieved by the printing, a gap of an ink key opening of the ink fountain (20) of the printing unit (10) to be adjusted during the printing, and an ink fountain roller (22) speed to be adjusted during the printing, wherein the specific ink coverage predetermined for each of the at least two different reference spot colors is different from one another, ii) printing each of the at least two different reference spot colors onto the substrate (18) predetermined in step a) with the printing unit (10) predetermined in step a) at the predetermined ink coverage, at the predetermined gap of the ink key opening of the ink slot (20) of the printing unit (10), at the predetermined ink fountain roller (22) speed and at an arbitrarily selected number of times that the vibrating roller contacts the ink fountain roller (22), iii) determining whether the predetermined specific ink coverage has been achieved on the substrate (18), wherein, if the predetermined specific ink coverage has been achieved on the substrate (18), the arbitrarily selected number of times the vibrating roller contacts the ink fountain roller (22) is saved as the appropriate number of times the vibrating roller contacts the ink fountain roller (22) for the corresponding reference spot color, and if the predetermined specific ink coverage has not been achieved on the substrate (18), repeating step ii) for the relevant reference spot color with one or more other arbitrarily selected numbers of times the vibrating roller contacts the ink fountain roller (22) so frequently until the predetermined specific ink coverage is achieved on the substrate (18), wherein the number of times the vibrating roller contacts the ink fountain roller (22) for achieving the predetermined specific ink coverage on the substrate (18) is saved as the appropriate number of times the vibrating roller contacts the ink fountain roller (22), and iv) calculating the number of times the vibrating roller contacts the ink fountain roller (22) to be used in step b) based on the appropriate number of times the vibrating roller contacts the ink fountain roller (22), the predetermined ink coverage, the predetermined gap of the ink key opening of the ink slot (20), and the predetermined ink fountain roller (22) speed for each of the at least two reference spot colors.

9. The method according to claim 8, wherein: In step i), the ink coverage of each of the reference spot colors is calculated as the product of the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking, and the predetermined specific ink coverage of the reference spot color to be achieved on the substrate (18), which is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate (18) with the predetermined printing unit (10).

10. The method according to claim 8 or 9, wherein: For each of the reference spot colors, the coefficient is calculated according to the following formula (1): K n =M n / (B n . DS n . NVR n ) (1) in: K means coefficient, n is an integer representing the number of the reference spot colors concerned, M is the amount of the spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit, expressing a specific grammage per square meter for the corresponding reference color, optionally adding the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking process, B is the gap of the ink key opening of the ink tank (20) used during the pre-inking process of the corresponding reference spot color, DS is the ink fountain roller (22) speed used during the pre-inking process of the corresponding reference spot color, and NVR is the number of times a vibrating roller contacts the ink fountain roller (22).

11. The method according to claim 10, further comprising: - calculating the ink coverage of the spot color necessary to achieve the specific ink coverage, which in turn is necessary to achieve the color coordinates of the spot color on the substrate (18) already predetermined in step a), the color coordinates of the spot color being the product of the total area to be inked of all rollers in the inking unit and the predetermined specific ink coverage to be achieved on the substrate (18), the total area optionally being added with the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking, - predetermining the ink fountain roller (22) speed used during the pre-inking process of the spot color, and - predetermining the gap of the ink key opening of the ink tank (20) used during the pre-inking process of the spot color, wherein the number of times the vibrating roller contacts the ink fountain roller, which is necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate (18) with the predetermined printing unit (10), is determined based on the predetermined ink coverage, preferably using a small laboratory printing press for printing and measuring the amount of applied ink, the predetermined ink fountain roller (22) speed, the predetermined gap of the ink key opening of the ink tank (20), and the coefficients K of the at least two reference spot colors n to calculate.

12. The method according to claim 11, wherein: Two reference spot colors are used, and wherein the method further comprises: v) calculating the coefficient K for the spot color predetermined in step a) according to formula (2): <h2 style=";text-align:left;direction:ltr">K = (K1-K2) / (M1-M2)<h2 style=";text-align:left;direction:ltr"> . <h2 style=";text-align:left;direction:ltr"> M + K1-((K1-K2) / (M1-M2))<h2 style=";text-align:left;direction:ltr"> . <h2 style=";text-align:left;direction:ltr"> M1 (2), in: K is the coefficient to be calculated for said spot color predetermined in step a), K1 is a coefficient that has been calculated for the first of the two reference spot colors according to formula (1), K2 is a coefficient that has been calculated for the second of the two reference spot colors according to formula (1), M is the amount of the spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit, determined in advance in step a), optionally adding the area of ​​the dampening roller if a dampening roller is connected to the rollers of the inking unit during the pre-inking process, M1 is the amount of first reference spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening roller is connected to the rollers of the inking unit during the pre-inking process, and M2 is the amount of second reference spot color ink in grams required to ink the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening roller is connected to the rollers of the inking unit during the pre-inking process, as well as vi) calculating the number of times the vibrating roller contacts the ink fountain roller (22), which number of times the vibrating roller contacts the ink fountain roller (22) is necessary to obtain a specified color coordinate for the spot color predetermined in step a) by printing the spot color onto the substrate (18) with the inking unit at the specific ink coverage that has been predetermined in step a), according to the following formula (3): NVR = M / (K . DS . B) (3), in: NVR is the number of times the vibrating roller contacts the ink fountain roller (22), which number of times the vibrating roller contacts the ink fountain roller (22) is necessary to obtain a specified color coordinate for the spot color predetermined in step a) by printing the spot color onto the substrate (18) with the inking unit at the specific ink coverage that has been predetermined in step a), M is defined as above with respect to formula (2), K is the coefficient calculated in step v) using formula (2), DS is the speed of the ink fountain roller (22) in meters per minute, and B is the gap of the ink key opening of the ink tank (20) used during the pre-inking process of the spot color.

13. The method according to claims 8 and 9, wherein: A polynomial trend line is determined for the specific ink coverage of each of the reference spot colors relative to the appropriate number of times the vibrating roller contacts the ink fountain roller (22) for each of the reference spot colors determined in step iii), wherein the number of times the vibrating roller contacts the ink fountain roller (22) necessary to obtain the specific ink coverage that has been predetermined in step a) by printing the predetermined spot color onto the predetermined substrate (18) using the predetermined printing unit (10) is determined based on the polynomial trend line.

14. The method according to claim 13, wherein: The polynomial trend line is of 2nd to 5th order, and preferably of 2nd to 4th order, wherein preferably the polynomial trend line is determined by using a least squares method.

15. The method according to claim 13 or 14, wherein: The polynomial trend line is determined using three to twenty, preferably five to twenty and more preferably eight to twelve reference spot colors, wherein preferably the predetermined specific ink coverage of all reference spot colors covers at least 1.2 to 1.6 g / m 2 , more preferably 1.0 to 1.8 g / m 2 And most preferably 0.8 to 2.0 g / m 2 The numerical range of .

16. The method according to claim 5, wherein: The determination in step b) of the number of times the vibrating roller contacts the ink fountain roller (22) necessary to obtain the specific ink coverage already predetermined in step a) by printing the predetermined spot color onto the predetermined substrate (18) with the predetermined printing unit (10) comprises the following considerations for each of the at least two different reference spot colors: a) the total area to be inked of all rollers in the inking unit, optionally plus the area of ​​the dampening roller if a dampening unit is connected to the inking unit during the pre-inking, b) the thickness of the ink film on the vibrating roller, c) the contact length between the ink fountain roller (22) and the vibrating roller, d) the physical density of the spot color, and d) The width of the ink groove.

17. The method according to claim 16, wherein: In step b), the number of times the vibrating roller contacts the ink fountain roller (22) necessary to obtain the specific ink coverage already predetermined in step a) by printing the spot colors onto the substrate (18) with the printing unit (10) is determined from at least two different reference spot colors and preferably from at least three different reference spot colors, each of the at least three different reference spot colors having been printed onto the substrate (18) already predetermined in step a) with the printing unit (10) i) with a different predetermined specific ink coverage, and ii) with a different or preferably the same predetermined ink film thickness on the vibrating roller, and / or iii) with a different or preferably the same predetermined contact length between the ink fountain roller (22) and the vibrating roller, and / or iii) with a different or preferably the same predetermined ink groove width.

18. The method according to claim 16 or 17, comprising: i) before printing the at least two different reference spot colors onto the substrate (18) predetermined in step a) with the printing unit (10) predetermined in step a), predetermining for each of the at least two different reference spot colors an ink coverage necessary to achieve a predetermined specific ink coverage to be achieved by the printing, a contact length between the ink fountain roller (22) and the vibrating roller to be adjusted during the printing, an ink film thickness on the vibrating roller to be adjusted during the printing, and an ink groove width to be adjusted during the printing, wherein the specific ink coverage predetermined for each of the at least two different reference spot colors is different from one another, ii) for each of the at least two different reference spot colors, calculating the number of times the vibrating roller contacts the ink fountain roller (22) required to ink the entire area of ​​the printing unit (10), iii) printing each of the at least two different reference spot colors onto the substrate (18) predetermined in step a) with the printing unit (10) predetermined in step a) at the predetermined ink coverage, at the predetermined contact length between the ink fountain roller (22) and the vibrating roller, at the predetermined ink film thickness on the vibrating roller, at the predetermined ink groove width and at an arbitrarily selected number of times the vibrating roller contacts the ink fountain roller (22), iv) determining whether the predetermined specific ink coverage has been achieved on the substrate (18), wherein, if the predetermined specific ink coverage has been achieved on the substrate (18), the arbitrarily selected number of times the vibrating roller contacts the ink fountain roller (22) is saved as the appropriate number of times the vibrating roller contacts the ink fountain roller (22) for the corresponding reference spot color, and if the predetermined specific ink coverage has not been achieved on the substrate (18), repeating step ii) for the relevant reference spot color with one or more other arbitrarily selected numbers of times the vibrating roller contacts the ink fountain roller (22) so frequently until the predetermined specific ink coverage is achieved on the substrate (18), wherein the number of times the vibrating roller contacts the ink fountain roller (22) for achieving the predetermined specific ink coverage on the substrate (18) is saved as the appropriate number of times the vibrating roller contacts the ink fountain roller (22), v) determining, preferably by using a least square method, a polynomial trend line of the appropriate number of times the vibrating roller contacts the ink fountain roller (22) determined in step iv) relative to the number of times the vibrating roller contacts the ink fountain roller (22) calculated in step ii) for the at least two different reference spot colors, and vi) calculating, for the spot color predetermined in step a), the number of times the vibrating roller contacts the ink fountain roller (22) required to ink the entire area of ​​the printing unit (10), and calculating therefrom, using the polynomial trend line predetermined in step v), the number of times the vibrating roller contacts the ink fountain roller (22) necessary to obtain the specific ink coverage predetermined in step a) by printing the predetermined spot color onto the predetermined substrate (18) with the predetermined printing unit (10).

Images