Printing press

Abstract

This invention provides a printing press that can suppress ink clouding that occurs when changing from an old ink to a new ink of a different color. [Solution] When a printing press changes the ink used for printing from old ink to new ink of a different color, it performs the following steps prior to supplying the new ink to the printing cylinder 2: a new ink supply step in which new ink is supplied from an ink fountain provided for the roller group R, which is composed of multiple rollers for supplying ink to the printing cylinder 2, after the old ink has been cleaned off the roller group R; and a new ink cleaning step in which any deposits, including the new ink, attached to the roller group R, which has the new ink attached to its surface as a result of the new ink supply step, are removed.

Description

【Technical Field】 【0001】 The present invention relates to a printing machine provided with a printing unit having a group of rollers for transferring the ink in an ink fountain to a plate cylinder. 【Background Art】 【0002】 When changing the printing ink to change the printing color in the printing unit of a printing machine (when changing colors), first, ink cleaning is performed to remove the old ink remaining in the printing unit. After that, new ink is supplied to the printing unit. The ink cleaning includes ink fountain cleaning and roller cleaning. 【0003】 Patent Document 1 describes an invention related to improving the operation of ink fountain cleaning. It is also described that roller cleaning has conventionally been performed automatically. Further, in the case of changing colors from a dark-colored ink to a light-colored ink, if the dark-colored ink, which is the old ink, remains in the roller group, the light-colored ink, which is the new ink, will become significantly turbid (due to ink turbidity), and it is also described that it is necessary to perform thorough roller cleaning. 【0004】 However, even if thorough roller cleaning is performed, a small amount of old ink may remain in the roller group. For example, there is a case where old ink that has penetrated into the surface layer of the roller remains. As a result, the remaining old ink mixes into the new ink, causing ink turbidity in the roller group and adversely affecting the color tone of the printed matter. 【Prior Art Documents】 【Patent Documents】 【0005】 【Patent Document 1】 Japanese Patent No. 3933246 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0006】 If the color tone of the printed material fell outside the acceptable range due to the aforementioned ink clouding, the rollers had to be thoroughly cleaned again, leading to inconveniences such as wasted printing materials and decreased work efficiency. 【0007】 This invention was made to solve these problems, and aims to provide a printing press that can suppress ink clouding that occurs when changing from old ink to new ink of a different color. [Means for solving the problem] 【0008】 To achieve the above objective, the printing press according to the present invention, when changing the ink used for printing from old ink to new ink of a different color, performs the following steps prior to supplying the new ink to the printing cylinder: a new ink supply step in which new ink is supplied from an ink fountain provided for the roller group, which is holding the new ink, to a roller group consisting of a plurality of rollers for supplying ink to the printing cylinder, after the old ink has been cleaned off the roller group; and a new ink cleaning step in which the roller group, to which the new ink has adhered to the surface as a result of the new ink supply step, removes any deposits including the new ink that have adhered to the roller group. 【0009】 According to the above configuration, when changing from old ink to new ink of a different color, the new ink is supplied from the ink fountain holding the new ink to the roller group, which has been cleaned of the old ink. By supplying the new ink and removing any deposits containing the new ink that have adhered to the roller group, the possibility of printing with the new ink used for printing after the color change being mixed with the old ink that remained on the roller group even after cleaning can be reduced. 【0010】 Furthermore, the printing press according to the present invention may perform an old ink cleaning step prior to the new ink supply step, on the roller group on which old ink is adhering to the surface, to remove the old ink adhering to the roller group. 【0011】 According to the above configuration, the old ink cleaning, new ink supply, and new ink cleaning can be performed in a single, continuous process. 【0012】 Furthermore, the printing press according to the present invention may be capable of adjusting the amount of new ink supplied from the ink fountain in the new ink supply step. 【0013】 According to the above configuration, a sufficient amount of new ink to carry out the new ink cleaning process can be effectively supplied. 【0014】 Furthermore, the printing press according to the present invention may be capable of adjusting the rotation speed of the roller group during the execution of the new ink supply process. 【0015】 According to the above configuration, by increasing the speed during the new ink supply process, for example, the diffusion of the new ink into the roller group can be accelerated, thereby shortening the time required for the new ink supply process. Furthermore, by increasing the speed, the centrifugal force and load fluctuations acting on the surface of each roller constituting the roller group are increased, promoting the movement of the old ink that has penetrated the surface layer of the rollers to the roller surface, thereby allowing more old ink to be included in the deposits removed in the new ink cleaning process. [Effects of the Invention] 【0016】 According to the present invention, a printing press can be provided that can suppress ink clouding that occurs when changing from old ink to new ink of a different color, by supplying new ink to a group of rollers that have been cleaned of old ink and removing any deposits containing new ink that have adhered to the group of rollers. [Brief explanation of the drawing] 【0017】 [Figure 1] This is a schematic diagram showing the internal structure of one printing unit that makes up a printing press. [Modes for carrying out the invention] 【0018】 Figure 1 shows the internal structure of one printing unit 1 that makes up a printing press, with the lower part omitted. Printing presses can be equipped with four, five, or six printing units to print in four basic colors (cyan, magenta, yellow, and black) or five or six colors including spot colors that are not basic colors, or they can be equipped with printing units for one or two or more colors in addition to four, five, or six colors. 【0019】 The printing unit 1 shown in Figure 1 comprises a plate cylinder 2 around which a plate (not shown) is wrapped, an ink supply device 3 that supplies ink to the plate on the plate cylinder 2, a dampening water supply device 4 that supplies dampening water to the plate on the plate cylinder 2, and a doctor blade 6 that supplies cleaning fluid for roller cleaning (described later) to a group of rollers R via rollers 5 and collects waste liquid mixed with ink and cleaning fluid. 【0020】 The printing unit 1 also includes a rubber cylinder 7 to which the ink supplied to the plate cylinder 2 is transferred, and an impression cylinder (not shown) that presses the printing paper between itself and the rubber cylinder 7 to print. 【0021】 The ink supply device 3 includes an ink fountain 8 that contains printing ink, an ink source roller 9 positioned on the ink fountain 8, and a group of rollers R that moves the ink from the ink fountain 8 from the ink source roller 9 to the plate cylinder 2. The ink fountain 8 is equipped with multiple ink fountain keys 10. The group of rollers R consists of multiple rollers for supplying ink to the plate cylinder 2, which are provided between the ink source roller 9 and the periphery of the plate cylinder 2. Specifically, the group of rollers R includes a call roller 11, a rolling roller 12, multiple ink mixing rollers R1 that mix the ink received by the rolling roller 12 and send it downstream, multiple ink application rollers R2 that supply ink to the plate cylinder 2, and a roller 5 to which a cleaning solution, etc., described later, is sprayed. 【0022】 The calling roller 11 reciprocates in a reciprocating motion so as to be alternately separable from and contact with the ink source roller 9 and the tumbling roller 12 adjacent downstream thereof. When the calling roller 11 is in contact with the ink source roller 9 (see the two-dot chain line), the calling roller 11 is separated from the tumbling roller 12. Also, when the calling roller 11 is in contact with the tumbling roller 12 (see the solid line), the calling roller 11 is separated from the ink source roller 9. This reciprocating motion is also referred to as an ink calling operation, and the greater the number of ink calling operations, the greater the amount of ink supplied to the roller group R. Further, each ink fountain key 10 is configured to be able to change the gap (so-called key opening) formed between the ink fountain key 10 and the ink source roller 9 by moving in the direction of arrow S. The greater the key opening, the thicker the ink film thickness formed on the outer peripheral surface of the ink source roller 9 with which the calling roller 11 contacts. Each ink fountain key 10 moves by the drive of an ink fountain key drive device (not shown). Incidentally, the ink fountain key 10 can also be configured to be able to change the key opening by moving in the direction of arrow H shown by the two-dot chain line. 【0023】 N shown in FIG. 1 is a cleaning nozzle for spraying a cleaning liquid or the like onto the roller 5 and supplying it to the roller group R. The reason for using a cleaning liquid or the like is that in addition to spraying only the cleaning liquid, there are also those that spray a mixture of a solvent such as water in the cleaning liquid, or those that alternately spray the cleaning liquid and water. In this embodiment, the cleaning nozzle N supplies a cleaning liquid or the like toward the roller 5 located at the uppermost position among the roller group R, but it may be other rollers. Also, a plurality of cleaning nozzles N may be provided and implemented. 【0024】 The doctor 6 includes a flat blade 61 that contacts the outer peripheral surface of a predetermined roller R3 that rotates counterclockwise to scrape off the waste liquid on the predetermined roller R3, and a cleaner 62 whose lower side portion of the blade 61 is fixed by screws or the like not shown. The predetermined roller R3 is located downstream of the roller group R and closer to the lower side. 【0025】 The doctor blade 6 is configured to rotate in the direction of arrow T in the figure by a mechanism including an actuator (not shown). In other words, by rotating the doctor blade 6 to the right in Figure 1, the blade 61 can be moved to a contact position where it contacts a predetermined roller R3 (see the dashed line in the enlarged view of Figure 1), and by rotating the doctor blade 6 to the left in Figure 1 from the contact position, the blade 61 can be moved away from the predetermined roller R3 (see the solid line in the enlarged view of Figure 1). 【0026】 The dampening water supply device 4 comprises a water tank 13 for storing dampening water, a water source roller 14 for drawing out the dampening water from the water tank 13, a metering roller 15 mounted so as to be in contact with the water source roller 14, a dampening roller 16 mounted so as to be in contact with the metering roller 15, and a transfer roller 17 and a water leveling roller 18 mounted so as to be in contact with the dampening roller 16. The dampening roller 16 is mounted so as to be in contact with the printing cylinder 2. The dampening water drawn up from the water tank 13 by the water source roller 14 is supplied to the dampening roller 16 via the metering roller 15, and then supplied from the dampening roller 16 to the printing cylinder 2. 【0027】 When changing the ink used for printing with the printing unit 1 configured as described above, from the old ink to a new ink of a different color (color change), ink cleaning is performed to remove the old ink. Ink cleaning involves cleaning the ink fountain and cleaning the rollers. Ink fountain cleaning is performed according to a conventionally known procedure, and the new ink is placed in the ink fountain 8 after cleaning. Roller cleaning is described below. When performing roller cleaning (especially the roller cleaning process B described later), it is preferable to keep all (four in Figure 1) the inking rollers R2 and the dampening rollers 16 separated from the plate cylinder 2. Alternatively, the transfer roller 17 may be kept separated from the inking rollers R2 and roller R4. Color changes may be performed on only one printing unit 1, or on any number of printing units 1, two or more. 【0028】 In this invention, roller cleaning consists of the following three steps: (1) roller cleaning step A, (2) new ink retrieval step, and (3) roller cleaning step B. Roller cleaning step A corresponds to the old ink cleaning step of the claim in this application. The new ink retrieval step corresponds to the new ink supply step of the claim in this application. Furthermore, roller cleaning step B corresponds to the new ink cleaning step of the claim in this application. 【0029】 (1) Roller cleaning process A Roller cleaning process A is a process performed prior to supplying new ink to the plate cylinder 2 for printing, and is a conventional roller cleaning process that has been carried out to remove old ink adhering to the roller group R. Specifically, (a) the printing press is rotated at a speed (rotation speed, e.g., 8000 rph) for roller cleaning. (b) Next, cleaning liquid (which may be water or a cleaning aid) is supplied to the roller group R from the cleaning nozzle N, and the blade 61 is brought into contact with the outer surface of a predetermined roller R3 to scrape off the waste liquid (a mixture of old ink and cleaning liquid adhering to the roller group R) and collect it in the cleaning device 62. After that, the blade 61 is moved away from the outer surface of the predetermined roller R3. (c) The printing press is rotated further to dry the cleaning liquid remaining on the roller group (drying process). Note that the drying process in (c) can be omitted if all of steps (1), (2), and (3) are performed continuously and automatically, or to shorten the time. Furthermore, it is preferable to change the plate on the plate cylinder 2 after (1) the roller cleaning process A is completed and before starting the next (2) new ink calling process. 【0030】 (2) New ink recall process The new ink recall process is a process in which new ink is supplied from the ink fountain 8 to the roller group R, which has been cleaned of old ink by the roller cleaning process A. Before starting the new ink recall process, the operator confirms that the ink in the ink fountain has been replaced with new ink. Prior to this, it is necessary that the ink fountain cleaning to remove the old ink from the ink fountain 8 has been performed. After confirmation, a predetermined amount of new ink is supplied from the ink fountain 8 to the roller group R. For example, all ink fountain keys 10 are set to a predetermined key opening and the ink recall operation of the recall roller 11 is performed for a predetermined period of time. Specifically, (a) the printing press is rotated and the ink source roller 9 is rotated to open all ink fountain keys 10 to a preset key opening. In this embodiment, all ink fountain keys 10 are set to the same key opening. (b) Next, the recall operation of the recall roller 11 is performed and new ink is supplied to the roller group R. (c) After supplying the new ink, the calling operation of the calling roller 11 is stopped. (d) The printing press is rotated for a set time to diffuse the new ink within the roller group R. As described above, by supplying the new ink to the roller group R, the old ink remaining in the roller group R is mixed with the new ink. Specifically, the old ink that has permeated the surface of the rollers is drawn into the new ink by the adhesive force of the new ink. Furthermore, if the amount of new ink supplied from the ink fountain 8 to the roller group R is configured to be adjustable during the new ink calling process, a sufficient amount of new ink can be effectively supplied to carry out the next process, the roller cleaning process B. In addition, the rotation speed of the roller group R may be configured to be adjustable during the new ink calling process. This allows for faster diffusion of the new ink into the roller group R by increasing the speed during the new ink calling process, thereby shortening the time required for the new ink calling process. Furthermore, by increasing the speed, the centrifugal force and load fluctuations acting on the surface of each roller constituting the roller group R are increased, promoting the movement of old ink that has penetrated the surface layer of the rollers to the roller surface. This allows the deposits to be removed in the next step, roller cleaning step B, to contain a larger amount of old ink. 【0031】 (3) Roller cleaning process B Roller cleaning process B is a process to remove deposits, including new ink, that have adhered to the roller group R by the new ink recall process. The deposits include old ink mixed with the new ink. Specifically, (a) the printing press is rotated at a speed for roller cleaning (for example, 8000 rph). (b) Next, cleaning liquid (which may be water or a cleaning aid) is supplied to the roller group R from the cleaning nozzle N, and the blade 61 is brought into contact with the outer surface of a predetermined roller R3 to scrape off the waste liquid (a mixture of new ink, a small amount of old ink, and cleaning liquid that has adhered to the roller group R) and collect it in the cleaning device 62. In roller cleaning process B, the first cleaning liquid is supplied for a set time → the blade 61 is brought into contact → the next cleaning liquid is supplied for a set time while the blade 61 is still in contact (multiple times). After that, the blade 61 is removed from the outer surface of the predetermined roller R3. (c) The printing press is further rotated, for example, at 8000 rph, to speed up the drying (volatilization) of any cleaning solution remaining on the roller group R. (d) After drying, the printing press is rotated at a low speed for a set time, or the printing press is stopped. After the roller cleaning process B is completed, a print job using new ink is started. 【0032】 In the roller cleaning of the present invention, it is possible to select and execute either "pre-cleaned ink-wrapped cleaning," which automatically and continuously performs the three steps described above: (1) roller cleaning step A, (2) new ink recall step, and (3) roller cleaning step B, or "ink-wrapped cleaning," which automatically and continuously performs the two steps described above: (2) new ink recall step and (3) roller cleaning step. When "ink-wrapped cleaning" is selected, it is necessary to perform the roller cleaning step corresponding to (1) roller cleaning step A in advance by individual operation by the operator. The selection and execution of "pre-cleaned ink-wrapped cleaning" and "ink-wrapped cleaning" can be performed using the operation stand (not shown) provided on the printing press. 【0033】 The printing press is equipped with an operation stand that has a control unit for managing and adjusting the printing press. The operation stand is equipped with a display unit, such as a touch panel, and the selection and execution of "pre-cleaning with ink wrapping" and "ink wrapping cleaning" can be performed using the GUI (Graphical User Interface) screen displayed on the display unit. The display unit can select and display multiple GUI screens corresponding to various statuses of the printing press and various functions that make up the printing press. The GUI screen is composed of multiple layers. Various functions can be adjusted, set, and executed using the GUI screen. When selecting and executing "pre-cleaning with ink wrapping" and "ink wrapping cleaning," the cleaning GUI screen, which is the GUI screen related to "cleaning," is used. 【0034】 Next, we will explain how to select and perform "Ink Wrap Cleaning." To perform "Ink Wrap Cleaning," the operator taps the "Cleaning" tab (button) from among the multiple tabs on the upper-level GUI screen, which switches to the cleaning GUI screen. The cleaning GUI screen displays tabs (buttons) for "Roller Cleaning," "Blanket Cleaning," "Ink Wrap Cleaning with Pre-cleaning," and "Ink Wrap Cleaning." When the operator taps the "Ink Wrap Cleaning" tab (button), the screen switches from the cleaning GUI screen to the ink wrap cleaning GUI screen. The ink wrap cleaning GUI screen displays a group of buttons for selecting which printing unit to clean, a "Start" button to begin ink wrap cleaning, and a group of buttons to select the degree of soiling (degree of cleaning). To select the degree of soiling (degree of cleaning), the operator taps one of the three buttons: "Heavy," "Medium," or "Light." Furthermore, the ink fountain cleaning GUI screen includes a display area for messages to remind the operator to start the ink fountain cleaning after changing the ink in the ink fountain. For example, a message such as "Have you changed the ink in the ink fountain with new ink?" will be displayed. The operator taps the "YES" button if they have changed the ink in the ink fountain with new ink, and the "NO" button if they have not. If the "YES" button is tapped, then tapping the "Start" button will automatically perform steps (2) and (3). Note that if the "NO" button is tapped, the "Start" button will not be accepted. 【0035】 The degree of soiling (degree of cleaning) is set to "heavy," "medium," or "light" in the memory of the control unit, with the number of times cleaning fluid is discharged from the cleaning nozzle N being preset. Cleaning fluid is discharged from the cleaning nozzle N only for the number of times set for the selected button. "Heavy" is set to the highest number of times, "light" to the lowest number of times, and "medium" to a number between "heavy" and "light." The contact start timing for bringing the blade 61 into contact with the outer circumferential surface of the predetermined roller R3 and the contact release timing for releasing the contact are also set according to these cleaning fluid discharge counts. 【0036】 <Other GUI screens> The memory unit also stores separate GUI screens for setting (changing) the roller cleaning process B corresponding to the three buttons "heavy," "medium," and "light" for the degree of soiling mentioned earlier. Similarly, the roller cleaning process A also stores separate GUI screens for setting (changing) the number of times the cleaning solution is dispensed for each of the "heavy," "medium," and "light" levels. Therefore, if the operator wants to change the number of times the cleaning solution is dispensed for each of the "heavy," "medium," and "light" levels in roller cleaning process A, they display the GUI screen for setting (changing) the "heavy," "medium," and "light" levels and change the setting. The same applies to roller cleaning process B. Furthermore, if the number of times the cleaning fluid is dispensed for "heavy," "medium," or "light" is changed, the contact start timing for when the blade 61 contacts the outer surface of the predetermined roller R3 and the contact release timing for when contact is released will be changed. However, if the contact start timing and contact release timing of the blade 61 corresponding to the number of times the cleaning fluid is dispensed are stored in a table in the storage unit of the control unit, the control unit may be configured to automatically select and store the contact start timing and contact release timing of the blade 61 corresponding to the changed number of times the cleaning fluid is dispensed. 【0037】 Furthermore, the memory unit also stores a separate GUI screen for setting (changing) the new ink recall process. This GUI screen allows the operator to set and store the printer rotation speed, ink fountain key opening, ink source roller rotation speed, number of ink recall operations, and printer rotation time after the ink recall operation stops for the new ink recall process. Therefore, if the operator wants to change the various settings for the new ink recall process, they display this GUI screen and change the settings. The default values ​​are the same as the values ​​used during start-inking (supplying enough ink to the roller group R to achieve a uniform standard ink film thickness on each roller as preparation before printing begins). 【0038】 In this invention, the following effects are achieved by performing the three steps described above: (1) roller cleaning step A, (2) new ink recall step, and (3) roller cleaning step B. Old ink can be suitably (at least more effectively than in the conventional method) removed from the roller group R. This suppresses ink clouding that occurs during color changes. This is particularly effective when changing from dark to light colors. It is also effective when changing to spot inks where color shifts are critical. 【0039】 Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. 【0040】 In the above embodiment, the cleaning GUI screen has tabs (buttons) labeled "Ink-Wrapped Cleaning with Pre-Cleaning" and "Ink-Wrapped Cleaning." However, the roller cleaning GUI screen, which is displayed when the "Roller Cleaning" tab is tapped on the cleaning GUI screen, may also have tabs (buttons) labeled "Ink-Wrapped Cleaning with Pre-Cleaning" and "Ink-Wrapped Cleaning." [Explanation of symbols] 【0041】 1…Printing unit, 2…Plate cylinder, 3…Ink supply device, 4…Water supply device, 5…Roller, 6…Doctor blade, 7…Rubber cylinder, 8…Ink fountain, 9…Ink source roller, 10…Ink fountain key, 11…Call roller, 12…Rolling roller, 13…Water tray, 14…Water source roller, 15…Measuring roller, 16…Water application roller, 17…Transfer roller, 18…Water leveling roller, 61…Blade, 62…Washer, H, S, T…Arrows, N…Washing nozzle, R…Roller group, R1…Ink mixing roller, R2…Ink application roller, R3…Designated roller

Claims

[Claim 1] When changing the ink used for printing from the old ink to a new ink of a different color, this process is carried out prior to supplying the new ink to the printing cylinder. A roller group comprising a plurality of rollers for supplying ink to the printing cylinder, wherein, after the old ink has been cleaned off the roller group, new ink is supplied from an ink fountain provided for the roller group, which holds new ink. A new ink cleaning step is performed to remove any deposits, including the new ink, that have adhered to the roller group, which has been treated by the new ink supply step, and which have been treated by the new ink supply step, A printing press that performs this task. [Claim 2] The printing press according to claim 1, wherein, prior to the new ink supply step, an old ink cleaning step is performed on the roller group, which has old ink adhering to its surface, to remove the old ink adhering to the roller group. [Claim 3] The printing press according to claim 1 or 2, wherein the amount of new ink supplied from the ink fountain in the new ink supply step can be adjusted. [Claim 4] The printing press according to claim 1 or 2, wherein the rotation speed of the roller group can be adjusted during the execution of the new ink supply process.

Images