JP2006027283A - Multicolor offset printing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multicolor offset printing machine which can effectively prevent the occurrence of uneven streaks in printing. <P>SOLUTION: Diameters of respective dampening rollers 33a, 33b, 33c and 33d of dampening water supply devices 21a, 21b, 21c and 21d are different from one another. More specifically, the dampening roller 33a has a diameter for setting the length of its outer periphery as A; the dampening roller 33b has a diameter for setting the length of its outer periphery as B larger than A; the dampening roller 33c has a diameter for setting the length of its outer periphery as C larger than B; and the dampening roller 33d has a diameter for setting the length of its outer periphery as D larger than C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multicolor offset printing machine.

  Such a multi-color offset printing machine supplies dampening water with a dampening water supply device to a plurality of printing plates and supplies ink with an ink supply device corresponding to each printing plate. Multi-color printing is performed by transferring the upper ink onto printing paper via a blanket. In such a multi-color offset printing press, a plurality of dampening water supply devices are provided corresponding to each printing plate in order to prevent inks of different colors from entering the dampening water supply device. ing.

  The dampening water supply device used in such a multicolor offset printing machine includes a water boat that stores dampening water, a water source roller that rotates in a state where a part of the water is immersed in the water boat, An intermediate roller that transmits dampening water pumped out from the water boat by the water source roller, and a swim roller that supplies dampening water received from the intermediate roller to the surface of the printing plate by rotating in contact with the printing plate And.

  When multi-color printing is executed using such a multi-color offset printing machine, a phenomenon occurs in which streak unevenness occurs at a position separated by a certain distance from the edge of the printed pattern. It has been clarified by the inventor's research that the stripe unevenness occurs at a position separated from the edge of the pattern by the outer peripheral length of the swim roller for the following reason.

  That is, when supplying the dampening water to the printing plate using the dampening water supply device described above, the swim roller rotates a plurality of times on the printing plate. At this time, the dampening water supplied to the printing plate by the first water roller is a sufficient amount of dampening water supplied from the water roller and the intermediate roller in a state where the water roller is not in contact with the printing plate. The dampening water supplied to the printing plate by the swim roller in the second rotation is the water source roller in parallel with the supply operation of supplying the dampening water to the printing plate in the first rotation. And dampening water supplied from the intermediate roller to the swim roller. For this reason, the supply amount of dampening water supplied from the swim roller to the printing plate is slightly different between the first rotation and the second rotation of the swim roller.

  In the case of monochromatic printing, it is unlikely that such fluctuations in the amount of dampening water supplied directly cause streaking during printing. However, in a multi-color offset printing press, fluctuations in the supply amount of dampening water in the printing plates of the respective colors act on the same position on the printing paper. As a result, streak unevenness occurs at a position separated from the edge of the pattern by the outer peripheral length of the swim roller.

  In a multicolor offset printing machine that includes a plate cylinder for mounting a plurality of printing plates on its outer periphery, and performs printing of a plurality of colors while the plate cylinder rotates once, the swim roller is not in contact with the printing plate Since the time becomes longer, the occurrence of such unevenness is particularly remarkable.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a multicolor offset printing machine capable of effectively preventing the occurrence of streak unevenness during printing.

  According to the first aspect of the present invention, dampening water is supplied to a plurality of printing plates of the same size corresponding to different printing colors by a dampening water supply device corresponding to the printing plates of the respective colors, and the printing plates of the respective colors are used. In a multicolor offset printing machine that performs multicolor printing by supplying ink on a printing plate of each color onto a printing paper through a blanket after supplying ink by an ink supply device corresponding to The fountain solution supply device includes a fountain roller for supplying fountain solution to the printing plate by rotating in contact with the corresponding printing plate. It is characterized by being different by about 1 mm to several mm every time.

  According to the second aspect of the present invention, dampening water is supplied to a plurality of printing plates of the same size corresponding to different printing colors by a dampening water supply device corresponding to the printing plate of each color, and printing of each color is performed. In a multicolor offset printing machine that executes multicolor printing by supplying ink on a printing plate of each color onto a printing paper through a blanket after supplying ink by an ink supply device corresponding to the plate, The dampening water supply device includes a dampening roller for supplying dampening water to the printing plate by rotating in contact with the corresponding printing plate, and the diameter of the dampening roller is set to supply dampening water for each color. It is characterized in that the diameter of the swim roller is changed by a minute diameter for each apparatus.

  According to the third aspect of the present invention, dampening water is supplied to a plurality of printing plates of the same size corresponding to different printing colors by a dampening water supply device corresponding to the printing plate of each color, and printing of each color is performed. In a multicolor offset printing machine that executes multicolor printing by supplying ink on a printing plate of each color onto a printing paper through a blanket after supplying ink by an ink supply device corresponding to the plate, The dampening water supply device includes a same-diameter swim roller for supplying dampening water to the printing plate by rotating in contact with the corresponding printing plate, and a gear reduction ratio for driving each of the dampening rollers. The rotation speed of the swim roller is made different for each color dampening water supply device.

  A fourth aspect of the present invention is the multicolor offset printing machine according to any one of the first to third aspects, further comprising a plate cylinder on which a plurality of printing plates are mounted.

  According to the first and second aspects of the present invention, the diameter of the watering roller that supplies the dampening water to the printing plate is made different for each dampening water supply device. The variation position of the dampening water supply amount can be varied, and the occurrence of streak unevenness during printing can be effectively prevented.

  According to the third aspect of the present invention, since the rotation speed of the dampening roller that supplies dampening water to the printing plate is made different for each dampening water supply device, dampening water is used for each dampening roller. Therefore, it is possible to effectively prevent streaks from occurring during printing.

  According to the invention described in claim 4, since the plate cylinder on which the plurality of printing plates are mounted is provided on the outer periphery thereof, even when the time during which the swim roller is not in contact with the printing plate becomes long, It becomes possible to effectively prevent the occurrence of streak unevenness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of a multicolor offset printing machine to which the present invention is applied will be described. FIG. 1 is a schematic diagram of a multicolor offset printing machine to which the present invention is applied.

  The multicolor offset printing machine records an image on a printing plate on which the images held in the first and second plate cylinders 11 and 12 are not recorded, and then makes ink supplied to the printing plate. Printing is performed by transferring to the printing paper held on the impression cylinder 15 via the first and second blanket cylinders 13 and 14.

  The multi-color offset printing machine includes a first plate cylinder 11 that can move between a first printing position indicated by a solid line in FIG. 1 and an image recording position indicated by a two-dot chain line, and a first printing cylinder indicated by a solid line in FIG. And a second plate cylinder 12 movable between the printing position and the image recording position.

  Around the first plate cylinder 11 moved to the first printing position, an ink supply device 20a for supplying black (K) ink to the printing plate and magenta (M) ink to the printing plate, for example. An ink supply device 20b for supplying water and dampening water supply devices 21a and 21b for supplying dampening water to the printing plate are arranged. Further, around the second printing cylinder 12 moved to the second printing position, an ink supply device 20c for supplying, for example, cyan (C) ink to the printing plate, and, for example, yellow (Y) to the printing plate. An ink supply device 20d for supplying the ink and dampening water supply devices 21c and 21d for supplying dampening water to the printing plate are disposed. Further, around the first plate cylinder 11 or the second plate cylinder 12 moved to the image recording position, a plate feeding unit 23, a plate discharging unit 24, an image recording device 25, and a development processing device 26 are arranged. Has been.

  The multicolor offset printing machine includes a first blanket cylinder 13 provided so as to be in contact with the first plate cylinder 11 and a second blanket provided so as to be in contact with the second plate cylinder 12. The cylinder 14, the impression cylinder 15 provided so as to be able to contact the first and second blanket cylinders 13, 14 at different positions, and the printing paper supplied from the paper supply unit 27 are transferred to the impression cylinder 15. And a paper discharge cylinder 17 around which a chain 19 for discharging printed printing paper received from the impression cylinder 15 is discharged to a paper discharge unit 28, and a blanket cleaning device 29.

  The first and second plate cylinders 11 and 12 are respectively connected to a plate cylinder moving mechanism (not shown), and the first or second printing position and the image recording position described above are driven by driving the plate cylinder moving mechanism. Move back and forth between. Further, by driving a motor (not shown), the first plate cylinder 11 rotates in synchronization with the first blanket cylinder 13 at the first printing position, and the second plate cylinder 12 is rotated at the second printing position. The second blanket cylinder 14 is configured to rotate in synchronization. Further, a plate cylinder rotating mechanism (not shown) is provided in the vicinity of the image recording position, and both the first and second plate cylinders 11 and 12 are moved to the image recording position. It is comprised so that it may rotate by the drive of a rotation mechanism.

  A plate feeding unit 23 and a plate discharging unit 24 are arranged around the first plate cylinder 11 or the second plate cylinder 12 moved to the image recording position.

  In the plate supply unit 23, a supply cassette 63 that stores a long roll-shaped printing plate on which no image is recorded in a light-tight state, and a front end portion of the printing plate drawn out from the supply cassette 63 is a first plate. A guide member 64 and a guide roller 65 for guiding the surface of the cylinder 11 or the second plate cylinder 12 and a cutter 66 for cutting a long printing plate into a sheet-like printing plate are provided. ing. Further, the first and second plate cylinders 11 and 12 are provided with a pair of gripping claws (not shown) for holding the leading end portion and the trailing end portion of the printing plate supplied from the plate feeding portion 23. .

  The plate discharging unit 24 discharges the printing plate peeled off by the action of the nail mechanism 73 for peeling off the printing plate held on the first plate cylinder 11 or the second plate cylinder 12 after the printing is completed. A conveyor mechanism 69 for conveying to the cassette 68 and a discharge cassette 68 are provided.

  The leading end portion of the printing plate drawn out from the supply cassette 63 in the plate supply unit 23 is guided by the guide roller 65 and the guide member 64, and is held in one holding nail of the first plate cylinder 11 or the second plate cylinder 12. It is done. Then, the first plate cylinder 11 or the second plate cylinder 12 is rotated by driving the plate cylinder rotation mechanism 30, and the printing plate is wound around the outer periphery of the first plate cylinder 11 or the second plate cylinder 12. Then, the rear end portion of the printing plate cut by the cutter 66 is held by the other holding nail. In this state, the printing held on the outer periphery of the first plate cylinder 11 or the second plate cylinder 12 by the image recording device 25 while rotating the first plate cylinder 11 or the second plate cylinder 12 at a low speed. An image is recorded by irradiating the surface of the plate with a modulated laser beam.

  The printing plate P mounted on the outer periphery of the first plate cylinder 11 has an image area 67a for printing with black ink by the image recording device 25 as shown in FIG. An image area 67b for printing with magenta ink is recorded. Further, the printing plate P mounted on the outer peripheral portion of the second plate cylinder 12 has an image area 67c for printing with cyan ink by the image recording device 25 as shown in FIG. An image area 67d for printing with yellow ink is recorded. The image area 67a and the image area 67b are recorded at positions where the image area 67a and the image area 67b are equally distributed (that is, 180 degrees apart from each other) when mounted on the outer periphery of the first plate cylinder 11. Similarly, the image area 67c and the image area 67d are recorded at positions where the image area 67c and the image area 67d are evenly distributed (ie, 180 degrees apart from each other) when mounted on the outer periphery of the second plate cylinder 12. The

  Referring to FIG. 1 again, as described above, around the first plate cylinder 11 moved to the first printing position, the ink supply device 20a and the ink supply device 20b are also used for the second printing. Around the second plate cylinder 12 moved to the position, an ink supply device 20c and an ink supply device 20d are arranged. Each of these ink supply devices 20a, 20b, 20c and 20d (referred to collectively as “ink supply device 20”) has a plurality of ink rollers and ink fountains 72.

  The ink rollers of the ink supply devices 20a and 20b are swung by the action of a cam (not shown). And by this rocking | fluctuation operation | movement, it is the ink supply apparatus 20a or 20b in arbitrary image areas of the two image areas 67a and 67b formed in the printing plate P hold | maintained at the outer peripheral part of the 1st plate cylinder 11. FIG. When the ink roller is brought into contact, ink can be supplied only to a necessary image area. Similarly, the ink rollers of the ink supply devices 20c and 20d also swing by the action of a cam (not shown). And by this rocking | fluctuation operation | movement, it is the ink supply apparatus 20c or 20d to arbitrary image area | regions of the two image area | regions 67c and 67d formed in the printing plate P hold | maintained at the outer peripheral part of the 2nd plate cylinder 12. FIG. When the ink roller is brought into contact, ink can be supplied only to a necessary image area.

  Referring to FIG. 1 again, dampening water supply devices 21a, 21b, 21c and 21d (referred to collectively as “dampening water supply device 21”) are applied to the printing plate P by the ink supply device 20. Before supplying ink, dampening water is supplied to the printing plate P. Among these fountain solution devices 21, the fountain solution supply device 21a is in the image area 67a of the printing plate P, the fountain solution supply device 21b is in the image region 67b of the printing plate P, and the fountain solution supply device 21c is in the printing area. The dampening water supply device 21d supplies dampening water to the image area 67c of the printing plate P and the image area 67d of the printing plate P, respectively.

  A development processing device 26 is disposed below the first plate cylinder 11 or the second plate cylinder 12 that has moved to the image recording position. The development processing device 26 includes a development unit, a fixing unit, and a diaphragm unit, and is configured to be movable up and down between a standby position indicated by a two-dot chain line and a development processing position indicated by a solid line in FIG.

  In the case where the printing plate P on which an image is recorded by the image recording device 25 is developed by the development processing device 26, the development is performed on the printing plate P that rotates together with the first plate cylinder 11 or the second plate cylinder. The contact portion, the fixing portion, and the aperture portion are sequentially brought into contact.

  The first and second blanket cylinders 13 and 14 provided so as to be in contact with the first and second plate cylinders 11 and 12 have the same diameter as the first and second plate cylinders 11 and 12. A blanket for ink transfer is mounted on the outer periphery. The first and second blanket cylinders 13 and 14 can be brought into contact with and separated from the first and second plate cylinders 11 and 12 and the impression cylinder 15 by a cylinder insertion mechanism (not shown).

  A blanket cleaning device 29 disposed between the first and second blanket cylinders 13 and 14 is a long cleaning unit that is attached to a path from a winding roll to a winding roll via a plurality of pressure rollers. The cleaning liquid is supplied to the cloth, and the surface of the first and second blanket cylinders 13 and 14 is brought into contact with the first and second blanket cylinders 13 and 14 by sliding them. Is to wash.

  The impression cylinder 15 provided so as to be in contact with the first and second blanket cylinders 13 and 14 has diameters of the first and second plate cylinders 11 and 12 and the first and second blanket cylinders 13 and 14. It has a diameter of 1/2. The impression cylinder 15 has a gripper (not shown) for holding and transporting the leading edge of the printing paper.

  In addition, the sheet feeding cylinder 16 disposed adjacent to the impression cylinder 15 has the same diameter as the impression cylinder 15. The paper feed cylinder 16 conveys the front end portion of the printing paper supplied one by one from the paper feed unit 27 by the reciprocating suction plate 74 by a gripper. The leading end of the printing paper held by the gripper is held by the gripper of the impression cylinder 15 when the printing paper is transferred from the paper supply cylinder 16 to the impression cylinder 15.

  Further, the paper discharge cylinder 17 disposed adjacent to the impression cylinder 15 has the same diameter as the impression cylinder 15. The paper discharge cylinder 17 has a structure in which a pair of chains 19 are wound around both ends thereof, and grippers are respectively disposed on the pair of chains 19. The leading end of the printing paper held by the gripper of the pressure drum 15 is held by any gripper of the paper discharge drum 17 when the printing paper is transferred from the pressure drum 15 to the paper discharge drum 17. Then, as the chain 19 moves, the printing paper is conveyed onto the paper discharge unit 28 and discharged.

  The paper feed cylinder 16 is connected to a drive motor via a belt (not shown). The paper feed cylinder 16, the pressure drum 15, the paper discharge cylinder 17, and the first and second blanket cylinders 13 and 14 are connected to each other by gears attached to their ends. Further, the first blanket cylinder 13 and the first plate cylinder 11 moved to the first printing position, and the second blanket cylinder 14 and the second plate cylinder 12 moved to the second printing position are: They are connected by gears attached to the end portions. Accordingly, the drive cylinder (not shown) drives the feed cylinder 16, the impression cylinder 15, the discharge cylinder 17, the first and second blanket cylinders 13 and 14, and the first and second plate cylinders 11 and 12. , Rotate in sync with each other.

  Next, plate making and printing operations by this multicolor offset printer will be described. FIG. 3 is a flowchart showing an outline of plate making and printing operations by this multicolor offset printing machine. The printing and plate making operations are for the case where multicolor printing is performed on printing paper with four colors of inks of yellow, magenta, cyan, and black.

  First, a plate making process is performed in which an image is recorded on the printing plate P on the first and second plate cylinders 11 and 12 and development processing is performed (step S1). This plate making process is executed according to the process shown in the flowchart of FIG. 4 as a subroutine.

  That is, first, the first plate cylinder 11 is moved to the image recording position indicated by the two-dot chain line in FIG. 1 (step S11).

  Next, the printing plate P is supplied to the outer periphery of the first plate cylinder 11 (step S12). The supply of the printing plate P is executed by holding the leading portion of the printing plate P drawn from the supply cassette 63 and the rear end portion of the printing plate P cut by the cutter 66 with a pair of gripping claws (not shown).

  Subsequently, an image is recorded on the printing plate P held on the outer periphery of the first plate cylinder 11 (step S13). This image recording is performed by rotating the first plate cylinder 11 at a low speed and irradiating a modulated laser beam onto the printing plate P held on the outer periphery of the first plate cylinder 11 from the image recording apparatus 25. Executed.

  Next, the printing plate P on which the image is recorded is developed (step S14). This development processing is performed on the printing plate P that rotates with the first plate cylinder 11 after the development processing device 26 is raised from the standby position indicated by the two-dot chain line in FIG. 1 to the development processing position indicated by the solid line. This is executed by sequentially bringing the contact portion, the fixing portion and the aperture portion into contact with each other.

  When the developing process is completed, the first plate cylinder 11 is moved to the first printing position indicated by the solid line in FIG. 1 (step S15).

  Subsequently, a plate making process for the printing plate P held on the outer periphery of the second plate cylinder 12 is performed by the same operation as in steps S11 to 15 (steps S16 to S20). And if the plate making to the printing plate P hold | maintained on the outer periphery of the 1st, 2nd plate cylinders 11 and 12 is complete | finished, a plate making process will be complete | finished.

  Referring to FIG. 3 again, when the plate making process is completed, a printing process for printing on printing paper using printing plates P on the first and second plate cylinders 11 and 12 is executed (step S2).

  In this printing process, first, each fountain solution supply device 21 and each ink supply device 20 are only connected to the corresponding image areas of the printing plates P held on the first and second plate cylinders 11 and 12. Make contact. Accordingly, the dampening water and the ink are supplied from the corresponding dampening water supply devices 21 and the ink supply devices 20 to the respective image regions 67a, 67b, 67c, and 67d. The ink supplied to the printing plate P is transferred to corresponding areas of the first and second blanket cylinders 13 and 14.

  Then, the printing paper is supplied to the paper feed cylinder 16. This printing paper is transferred from the paper feed cylinder 16 to the impression cylinder 15. When the impression cylinder 15 continues to rotate in this state, the impression cylinder 15 has a diameter that is ½ of the first and second plate cylinders 11 and 12 and the first and second blanket cylinders 13 and 14. Therefore, black and cyan inks are transferred to the printing paper held on the outer periphery of the impression cylinder 15 in the first rotation, and magenta and yellow inks are transferred in the second rotation.

  In this way, the leading end portion of the printing paper on which printing of four colors has been completed is transferred from the impression cylinder 15 to the discharge cylinder 17. Then, the printing paper on which the printing of the four colors has been completed is conveyed toward the paper discharge unit 28 by the drive of the pair of chains 19 and is discharged onto the paper discharge unit 28.

  When the printing process is completed, the printing plate P used for printing is discharged (step S3). In order to discharge the printing plate P, the first plate cylinder 11 is first moved to an image recording position indicated by a two-dot chain line in FIG. Then, the first plate cylinder 11 is rotated counterclockwise, and the end portion of the printing plate P held on the first plate cylinder 11 is peeled off by the claw mechanism 73, and then the printing plate P is transferred to the conveyor mechanism. It is guided by 69 and discharged into the discharge cassette 68. Then, after returning the first plate cylinder 11 to the first printing position, the second plate cylinder 12 is moved from the second printing position to the image recording position, and the same operation as described above is executed. The printing plate P held on the second plate cylinder 12 is discharged into the discharge cassette 68.

  When the discharge process of the printing plate P is completed, the first and second blanket cylinders 13 and 14 are cleaned by the blanket cylinder cleaning device 29 (step S4).

  When the cleaning of the first and second blanket cylinders 13 and 14 is completed, it is confirmed whether or not another printing paper is to be printed (step S5). When other printing work is performed, the operations in steps 1 to 4 are repeated.

  When the printing operation is completed, the ink is washed (step S6). This ink cleaning is performed by removing and cleaning ink adhering to the ink roller and the ink fountain 72 in each ink supply device 20 by an ink cleaning device (not shown) disposed in each ink supply device 20.

  When the ink cleaning process is completed, all processes are completed.

  Next, features of the present invention will be described. FIG. 5 is an enlarged view showing the arrangement of the first and second plate cylinders 11 and 12, the ink supply devices 20a, 20b, 20c and 20d and the fountain solution supply devices 21a, 21b, 21c and 21d. .

  The dampening water supply device 21a described above includes a water boat 30a that stores dampening water, a water source roller 31a that rotates while being partially immersed in the water boat 30a, and a water source roller 31a. The dampening received from the intermediate roller 32a by rotating in contact with the intermediate roller 32a for transmitting the dampening water pumped out from the boat 30a and the printing plate P mounted on the outer periphery of the first plate cylinder 11. A dampening roller 33a for supplying water to the surface of the printing plate P.

  Similarly, the dampening water supply device 21b includes a water boat 30b, a water source roller 31b, an intermediate roller 32b, and a swim roller 33b. The dampening water supply device 21c includes a water boat 30c and a water source roller. The dampening water supply device 21d includes a water boat 30d, a water source roller 31d, an intermediate roller 32d, and a swim roller 33d.

  Next, a rotation drive mechanism for rotating each of the swim rollers 33a, 33b, 33c, and 33d in a state of contacting the printing plate P mounted on the outer periphery of the first and second plate cylinders 11 and 12 is used. The configuration will be described. FIG. 6 is a schematic side view of a rotational drive mechanism 50d for rotationally driving the swim roller 33d, and FIG. 7 is a schematic front view thereof.

  In the following description, the rotational drive mechanism 50d for rotating the swim roller 33d will be described. However, the rotational drive mechanism having the same configuration is also applied to the other swim rollers 33a, 33b, 33c. It is arranged.

  A gear 34 is disposed via a one-way clutch 35 on the side of the swim roller 33d. The gear 34 is connected to a gear 37 fixed to a shaft 39 having a synchronous pulley 38 at the other end via a gear 36. The synchronous pulley 38 fixed to the shaft 39 is engaged with a synchronous belt 44 wound around a synchronous pulley 42 fixed to a shaft 41 having a gear 45 at the other end and a tension pulley 43. The gear 45 fixed to the shaft 41 is engaged with a gear 48 that rotates in synchronization with the second plate cylinder 12 via a gear 46 and a gear 47. For this reason, the swim roller 33d rotates in the same circumferential direction at the same circumferential speed in synchronization with the second plate cylinder 12.

  The swim roller 33a and the swim roller 33b are rotated at the same peripheral speed in the same circumferential direction in synchronization with the first plate cylinder 11 by a drive mechanism similar to the drive mechanism shown in FIGS. Further, the swim roller 33c rotates in the same circumferential direction at the same peripheral speed in synchronization with the second plate cylinder 12 by a drive mechanism similar to the drive mechanism shown in FIGS.

  In the multi-color offset printing press having the above-described configuration, conventionally, the diameters of the swim rollers 33a, 33b, 33c, and 33d in the dampening water supply devices 21a, 21b, 21c, and 21d are the same. It was. For this reason, as described above, there has been a phenomenon in which streak unevenness occurs at a position separated from the edge of the printed pattern by a certain distance.

  That is, when the outer peripheral length of each of the swim rollers 33a, 33b, 33c, 33d is H, each printing plate P is printed at a position separated from the edge of the image areas 67a, 67b, 67c, 67d by a distance H on each printing plate P. The operation of supplying the dampening water to the plate P is switched from the first rotation to the second rotation of each of the swim rollers 33a, 33b, 33c, 33d, and the printing plate is switched from each of the swim rollers 33a, 33b, 33c, 33d. The amount of dampening water supplied to P varies slightly at this position. For this reason, as shown in FIG. 8, streak unevenness due to fluctuations in the amount of dampening water supplied to each printing plate P occurs at a position separated from the leading edge of the printed pattern G on the printing paper S by a distance H. To do.

  In order to cope with such a problem, in the dampening water supply devices 21a, 21b, 21c, and 21d according to this embodiment, the diameters of the respective swim rollers 33a, 33b, 33c, and 33d are different from each other. More specifically, the swim roller 33a has a diameter with an outer peripheral length A, the swim roller 33b has a diameter with an outer peripheral length B greater than A, and the swim roller 33c has an outer peripheral length C greater than B. Further, the diameter of the swim roller 33d is such that its outer peripheral length is D larger than C.

  In the case of adopting such a configuration, as shown in FIG. 9, the dampening water supply device 21a is dampened at a position separated from the tip of the pattern G by a distance A corresponding to the outer peripheral length of the swim roller 33a. Fluctuation in the supply amount of water occurs, and in the dampening water supply device 21b, fluctuations in the supply amount of dampening water occur at a position separated from the tip of the pattern G by a distance B corresponding to the outer peripheral length of the swim roller 33b. With respect to the dampening water supply device 21c, fluctuations in the dampening water supply amount occur at a position separated from the tip of the pattern G by a distance C corresponding to the outer peripheral length of the swim roller 33c. The supply amount of dampening water varies at a position separated from the tip of G by a distance D corresponding to the outer peripheral length of the swim roller 33d.

  In this way, the amount of dampening water supplied for each of the image areas 67a, 67b, 67c, 67d in each printing plate P shown in FIG. 2 is made different by making the diameters of the respective swim rollers 33a, 33b, 33c, 33d different. When the fluctuation positions of the dampening water are different, fluctuations in the supply amount of the dampening water do not act on the same portion of the printing paper S. For this reason, it becomes possible to effectively prevent the occurrence of streak unevenness at a position separated from the edge of the pattern by the outer peripheral length of the swim roller due to the variation in the supply amount of the dampening water.

  The difference in diameter between the above-mentioned swim rollers 33a, 33b, 33c, and 33d is, for example, about 1 to several mm. When the diameters are different from each other by 1 mm, the outer peripheral lengths are different by 3 mm or more, and it is possible to effectively prevent the above-described streak unevenness. At this time, when the diameter of each of the water-filling rollers 33a, 33b, 33c, and 33d is changed by about 1 to several millimeters, it is necessary to change other configurations of the dampening water supply devices 21a, 21b, 21c, and 21d. Therefore, it is not necessary to complicate the configuration of the dampening water supply devices 21a, 21b, 21c, and 21d.

  In the above-described embodiment, the diameters of the respective swim rollers 33a, 33b, 33c, and 33d are all different. However, even when some of these diameters have the same value, Compared with the case where these diameters are all the same, the effect of making the unevenness of the stripes inconspicuous is achieved. The present invention includes such an embodiment.

  Next, another embodiment of the present invention will be described.

  In the first embodiment described above, the unevenness of the streaks is prevented by making the diameters of the swim rollers 33a, 33b, 33c, and 33d different from each other. On the other hand, in this 2nd Embodiment, generation | occurrence | production of a stripe | line | muscle nonuniformity is prevented by varying the rotational speed of each swimsuit roller 33a, 33b, 33c, 33d.

  In the multi-color offset printing press according to the second embodiment, the gear 48 shown as a representative in FIGS. 6 and 7 in each rotational drive mechanism for rotationally driving the respective swim rollers 33a, 33b, 33c, 33d. The speed reduction ratio from the gear 34 to the gear 34 is different for each rotary drive mechanism. For this reason, the rotational speeds of the respective swim rollers 33a, 33b, 33c, and 33d are different from each other.

  That is, in the first embodiment described above, each of the swim rollers 33a, 33b, 33c, 33d is wet on the surface of the printing plate P while rotating at the same peripheral speed as the first and second plate cylinders 11, 12. In this second embodiment, the dampening water is supplied to the surface of the printing plate P in a state where the rotation speeds thereof are slightly different from each other. The reduction ratio of each rotary drive mechanism is set so as to be supplied.

  Even when such a configuration is adopted, the amount of dampening water supplied varies for each of the image areas 67a, 67b, 67c, and 67d in each printing plate P shown in FIG. 2 as in the case of the first embodiment described above. The positions will be different, and fluctuations in the supply amount of dampening water will not act on the same portion of the printing paper S. For this reason, it becomes possible to effectively prevent the occurrence of streak unevenness at a position separated from the edge of the pattern by the outer peripheral length of the swim roller due to the variation in the supply amount of the dampening water.

  In the above-described embodiment, a case has been described in which the present invention is applied to a multicolor offset printing machine that receives image data and makes a printing plate, and executes printing using the printing plate after plate making. The present invention can be similarly applied to a normal multi-color offset printing machine that executes only printing.

1 is a schematic diagram of a multicolor offset printing machine to which the present invention is applied. FIG. 6 is an explanatory diagram showing an arrangement of image areas 67 on a printing plate P. It is a flowchart which shows the outline | summary of the plate making and printing operation by this multicolor offset printing machine. It is a flowchart which shows a plate making process. FIG. 2 is an enlarged view showing the arrangement of first and second plate cylinders 11 and 12, ink supply devices 20a, 20b, 20c and 20d and dampening water supply devices 21a, 21b, 21c and 21d. It is a side surface schematic diagram of the rotational drive mechanism 50d. It is a front schematic diagram of the rotation drive mechanism 50d. It is explanatory drawing which shows the fluctuation | variation position of the supply amount of dampening water. It is explanatory drawing which shows the fluctuation | variation position of the supply amount of dampening water.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 1st plate cylinder 12 2nd plate cylinder 13 1st blanket cylinder 14 2nd blanket cylinder 15 Impression cylinder 16 Paper feed cylinder 17 Paper discharge cylinder 19 Chain 20 Ink supply apparatus 21 Dampening water supply apparatus 23 Plate supply Section 24 Discarding section 25 Image recording apparatus 26 Development processing apparatus 27 Paper feeding section 28 Paper discharge section 29 Blanket cleaning apparatus 30a Water boat 30b Water boat 30c Water boat 30d Water boat 31a Water source roller 31b Water source roller 31c Water source roller 31d Water Original roller 32a Intermediate roller 32b Intermediate roller 32c Intermediate roller 32d Intermediate roller 33a Swim roller 33b Swim roller 33c Swim roller 33d Swim roller 34 Gear 35 One-way clutch 36 Gear 37 Gear 38 Synchronous pulley 39 Axis 41 Axis 42 Synchronous pulley 43 Tension pulley 44 Synchronous belt 45 Ya 46 gear 47 gear 48 gear 72 ink fountain G picture P printing plate S Printing Paper

Claims (4)

For a plurality of printing plates of the same size corresponding to different printing colors, dampening water is supplied by a dampening water supply device corresponding to each color printing plate, and ink is supplied by an ink supply device corresponding to each color printing plate. In a multi-color offset printing machine that performs multi-color printing by transferring ink on a printing plate of each color onto a printing paper through a blanket after being supplied,
The fountain solution supply device for each color includes a swim roller for supplying fountain solution to the printing plate by rotating in contact with the corresponding printing plate,
A multi-color offset printing machine characterized in that the diameter of the swim roller is varied by about 1 mm to several mm for each color dampening water supply device. For a plurality of printing plates of the same size corresponding to different printing colors, dampening water is supplied by a dampening water supply device corresponding to each color printing plate, and ink is supplied by an ink supply device corresponding to each color printing plate. In a multi-color offset printing machine that performs multi-color printing by transferring the ink on the printing plate of each color onto the printing paper through a blanket,
The fountain solution supply device for each color includes a swim roller for supplying fountain solution to the printing plate by rotating in contact with the corresponding printing plate,
A multi-color offset printing machine characterized in that the diameter of the swimsuit roller is varied by a minute diameter for each color dampening water supply device. For a plurality of printing plates of the same size corresponding to different printing colors, dampening water is supplied by a dampening water supply device corresponding to each color printing plate, and ink is supplied by an ink supply device corresponding to each color printing plate. In a multi-color offset printing machine that performs multi-color printing by transferring the ink on the printing plate of each color onto the printing paper through a blanket,
The fountain solution supply device for each color includes a squeeze roller of the same diameter for supplying the fountain solution to the printing plate by rotating in contact with the corresponding printing plate,
A multi-color offset printing machine characterized in that the rotational speed of the swim roller is made different for each fountain solution supply device by varying the gear reduction ratio for driving each swim roller. In the multi-color offset printing press according to any one of claims 1 to 3,
A multicolor offset printing machine having a plate cylinder on which a plurality of printing plates are mounted.

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