Printing press

Abstract

To provide a printer capable of suppressing the occurrence of labor of cleaning.SOLUTION: A printer includes: an ink roller group having a plurality of ink rollers for sending ink from an ink fountain to a plate cylinder; a blade 22 for scraping ink E on a prescribed ink roller 41 among the plurality of ink rollers; and a recovery container 25 for recovering the scraped ink E. The blade 22 is movable between a contact position for scraping the ink E on the ink roller 41 by coming in contact with the ink roller 41, and a separation position separated from the ink roller 41. The ink roller 41 is rotated in a first rotation direction when scraping ink on the ink roller 41 by the blade 22, and includes a control part F for controlling the position change of the blade 22 and the rotation of ink roller 41. The control part F changes a position of the blade 22 in a contact position to a separation position, and rotates the ink roller 41 in a second rotation direction opposite to the first rotation direction with the position change of the blade 22.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a printing press. [Background technology]

[0002] For example, Patent Document 1 describes a method of scraping off ink to quickly reduce the amount of ink (ink film thickness) on the ink roller in the ink section. This ink scraping is performed by contacting a blade (also called a doctor blade) with the outer circumferential surface of a specific ink roller among a group of rotating ink rollers for a set time to scrape off the ink on the ink roller and collect it in a collection container. After the set time has elapsed, the blade is moved to a separation position away from the outer circumferential surface of the ink roller.

[0003] However, when the blade is separated from the ink roller, as shown in Fig. 6, ink stringing 27 occurs between the tip 22F of the blade 22 and the outer circumferential surface 41A of the specified ink roller 41. This stringing 27 occurs when the ink stretches and hangs down between the separated blade 22 and the specified ink roller 41, and is a phenomenon that occurs due to the viscosity of the ink. The ink E in the hanging state breaks off due to its own weight and falls out of the recovery container 25 from between the tip 22F of the blade 22 and the outer circumferential surface 41A of the specified ink roller 41 (as shown by the dashed line in Fig. 6), or it may wrap around and adhere to the back surface 22c of the blade 22, resulting in the inconvenience of requiring cleaning. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-116012 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve such problems, and an object of the present invention is to provide a printing press that can reduce the need for cleaning. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a printing machine according to the present invention comprises an ink roller group having a plurality of ink rollers for sending ink from an ink fountain to a plate cylinder, a blade for scraping off ink on a predetermined ink roller among the plurality of ink rollers, and a recovery container for recovering the ink scraped off by the blade, the blade being configured to be movable between a contact position where it contacts the predetermined ink roller to scrape off the ink on the predetermined ink roller and a separation position away from the predetermined ink roller, the predetermined ink roller being configured to rotate in a first rotation direction when the blade scrapes off the ink on the predetermined ink roller, and a control unit for controlling the change in position of the blade and the rotation of the predetermined ink roller, the control unit being configured to change the position of the blade from the contact position to the separation position, and to rotate the predetermined ink roller in a second rotation direction opposite to the first rotation direction in conjunction with the change in position of the blade.

[0007] According to the above configuration, by rotating the specified ink roller in a second rotation direction opposite to the first rotation direction as the blade at the contact position where ink scraping is completed is moved to the separated position, the ink forming stringiness that occurs between the tip of the blade and the outer circumferential surface of the specified ink roller is moved so as to be taken up by the ink roller rotating in the second rotation direction. This makes it difficult for stringiness to occur between the tip of the blade and the outer circumferential surface of the specified ink roller, or if it does occur, it is quickly eliminated, so that it is possible to prevent the ink from falling out of the collection container or from wrapping around and adhering to the back surface of the blade. It is also possible to prevent printing defects caused by stringiness.

[0008] In addition, the printing machine of the present invention may be configured so that the blade contacts the specified ink roller in an inclined position with the tip side facing diagonally upward at the contact position, and the control unit may be configured to change the position of the blade to the contact position to scrape off the ink, then stop the rotation of the specified ink roller in the first rotation direction and maintain the stop for a specified period of time before changing the position of the blade from the contact position to the separated position.

[0009] As described above, after the blade is shifted to the contact position to scrape off the ink, the rotation of the designated ink roller in the first rotation direction is stopped for a designated time, so that the scraped ink remaining on the blade gradually flows downward and is collected in the collection container. This makes it difficult for stringing to occur between the tip of the blade and the outer circumferential surface of the designated ink roller when the blade is shifted from the contact position to the separated position after the designated time.

[0010] In addition, in the printing press of the present invention, the separation distance between the tip of the blade and the outer peripheral surface of the specified ink roller at the separated position of the blade may be set to a distance that allows ink to be held between the blade and the specified ink roller without dripping.

[0011] As described above, if the distance between the tip of the blade and the outer peripheral surface of the designated ink roller at the blade separated position is set to a distance that allows the ink to be held between the blade and the designated ink roller without dripping, it is possible to prevent the ink in a stringy state from breaking off and falling.

[0012] In the printing press according to the present invention, it is preferable that the separation distance is set to any value between 0.5 mm and 3.0 mm. Effect of the Invention

[0013] According to the present invention, a printing machine can be provided that can reduce the need for cleaning by rotating a specified ink roller in a second rotation direction opposite to the first rotation direction as the blade from the contact position is shifted to the separated position. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic vertical sectional side view of a printing press according to the present invention; [Diagram 2] FIG. 2 is an enlarged view of the ink supply section of a printing press. [Diagram 3] 13 is a diagram illustrating a state in which a blade is brought into contact with a predetermined ink roller to scrape off ink. FIG. [Figure 4] 13 is a diagram illustrating a state in which the blade is separated from a predetermined ink roller after the ink has been scraped off, and the rotation of the predetermined ink roller is stopped. FIG. [Diagram 5] 5 is a diagram illustrating a state in which a predetermined ink roller is rotated in a direction opposite to that during scraping from the state shown in FIG. 4. FIG. [Figure 6] FIG. 13 is a diagram showing a conventional example in which stringing occurs between the tip of a blade and the outer circumferential surface of an ink roller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a printing press according to an embodiment of the present invention will be described with reference to the drawings.

[0016] FIG. 1 shows a printing press having an ink scraping function, which is a sheet-fed offset printing press (hereinafter simply referred to as a printing press). This printing press includes a paper feed section A for feeding sheets as printing paper one by one from a paper stack, a printing section B for printing on the sheets from the paper feed section A, a surface treatment section C for performing surface treatment on the sheets printed in the printing section B, and a paper discharge section D for discharging the sheets. Here, the printing section B is a printing section B having four printing units 5 so that four colors can be printed, but it may be a printing section that can print colors other than four colors, that is, one color, two colors, three colors, or five or more colors. In addition, the specific configuration of each section that constitutes the printing press is not limited to that shown in FIG. 1.

[0017] The printing unit 5 includes a plate cylinder 1, a blanket cylinder 2, a group of ink rollers 4, an impression cylinder 3, and a transfer cylinder 6. Although not shown, each impression cylinder 3 is provided with grippers at two locations (or one or more locations) in the circumferential direction for gripping the fed paper sheet with a claw base and claw. Reference numeral 7 denotes a paper feed cylinder, which receives a paper sheet transported over a feeder board 8 and a mouth plate 9 from a swing arm 10 and passes it to the impression cylinder 3. The paper feed cylinder 7 and the swing arm 10 are also provided with a claw base and claws. A printing plate (not shown) on which an image is formed is wound around and fixed to the plate cylinder 1.

[0018] The paper discharge section D is composed of a chain conveying device equipped with two paper discharge cylinders and grippers. That is, a first paper discharge cylinder 11 adjacent to the impression cylinder 3 of the surface treatment section C and a second paper discharge cylinder 12 adjacent thereto are provided, and an endless chain 15 is wound between a sprocket 13 provided at the front side (upstream side) in the conveying direction of the paper sheet and a sprocket 14 provided at the rear side (downstream side) in the conveying direction of the paper sheet, and the chain 15 rotates while being restricted by a chain guide (not shown) by the rotation of the sprockets 13 and 14. The paper sheet conveyed to the second paper discharge cylinder 12 is gripped by a plurality of chain grippers (not shown) fixed at predetermined intervals to the chain 15 and discharged.

[0019] 1, the surface treatment section C is provided with a varnishing plate cylinder 16 that faces and abuts against the impression cylinder 3. Also, although not shown, an anilox roller that abuts against the varnishing plate cylinder 16 and supplies varnish is provided. The surface treatment section C also includes a cylinder lifting device (not shown) that supports the varnishing plate cylinder 16 so that it can be raised and lowered relative to the impression cylinder 3.

[0020] 2 is an enlarged view of the ink supply section. The ink fountain roller 18, which receives ink from an ink fountain 17, rotates counterclockwise in the figure and supplies ink to the ink roller group 4, which is composed of multiple ink rollers located downstream, via the adjacent ink call roller 19. Although the ink call roller 19 is not shown in detail, it reciprocates so as to be able to come into contact with and separate from the ink fountain roller 18 and the lateral roll roller 20 adjacent to it on the downstream side. In other words, when the ink call roller 19 is in contact with the ink fountain roller 18, the ink call roller 19 is separated from the lateral roll roller 20. This reciprocating motion is also called the ink call operation, and the more times the ink is called out, the greater the amount of ink supplied to the ink roller group 4. In addition, the ink fountain key K of the ink fountain 17 can be moved in the direction of arrow S to come into contact with or separate from the ink fountain roller 18, and the further the ink fountain key K is from the ink fountain roller 18, the greater the opening of the ink fountain key K and the greater the amount of ink supplied onto the ink fountain roller 18. The ink fountain key K is moved by driving an ink fountain key drive motor (not shown). Note that the ink fountain key K can also be configured to be able to come into contact with or separate from the ink fountain roller 18 by rotating in the direction of arrow R shown by an imaginary line. Reference numeral 21 in Figure 2 is a cleaning nozzle that supplies cleaning liquid to the ink roller group 4 for cleaning the ink roller group 4.

[0021] The ink fountain keys K are arranged in a row in the axial direction of the ink fountain roller 18 (see FIG. 2), i.e., in the width direction of the printed matter (the direction perpendicular to the transport direction). The opening degree of the ink fountain keys K relative to the ink fountain roller 18 is determined for each ink fountain key according to the amount of ink required based on the print image.

[0022] A blade (also called a doctor blade) 22 for reducing the ink film thickness on the predetermined ink roller 41 is provided to the left of one predetermined ink roller 41 (the second ink roller from the bottom on the left side in FIG. 2) in the ink roller group 4. The blade 22 is configured to rotate in the direction of arrow T by the expansion and contraction of an air cylinder 23, which is an example of an actuator. Specifically, a tip end of a piston rod 23A of the air cylinder 23 is connected to one end of an arm 24, and the other end of the arm 24 is linked to the lower end of a collection container 25 to which the blade 22 is attached. Therefore, the blade 22 can be moved to a contact position (see FIG. 3) where the recovery container 25 is rotated clockwise around the axis X parallel to the rotation axis of the predetermined ink roller 41 by extending the air cylinder 23 in FIG. 2 and contacted with the predetermined ink roller 41, and to a separation position (see FIG. 4 and FIG. 5) where the recovery container 25 is rotated counterclockwise around the axis X parallel to the rotation axis of the predetermined ink roller 41 by contracting the air cylinder 23 in the opposite manner to the above. The dimension of the blade 22 in the width direction (the direction penetrating the paper surface of FIG. 2) is set to be longer than the dimension of the predetermined ink roller 41 in the width direction. This predetermined ink roller 41 is configured to be able to not only rotate but also move in the rotation axis direction (the direction penetrating the paper surface of FIG. 2) when feeding ink, so the dimension of the blade 22 in the width direction is set to cover the amount of movement in the rotation axis direction. The width of the collection container 25 is also set in accordance with the width of the blade 22 .

[0023] As shown in Fig. 3, the blade 22 has a flat blade portion 22A that contacts the outer peripheral surface of the predetermined ink roller 41 and a support portion 22B that supports the lower portion of the blade portion 22A, and the support portion 22B is fixed to the inside of an upper wall portion 25a (described later) that constitutes the collection container 25 by a plurality of screws 26. The blade portion 22A is made of a hard synthetic resin and is thinner toward the tip, so that the ink can be scraped off reliably. The support portion 22B has an inclined surface 22b whose upper end is located closer to the predetermined ink roller 41, so that the ink scraped off by the blade portion 22A can be smoothly guided to the lower portion of the collection container 25 through the inclined surface 22b.

[0024] As shown in FIG. 3, the collection container 25 is configured to have a substantially V-shaped cross section, and includes a plate-shaped first inclined wall portion 25A on the side of the predetermined ink roller 41, a plate-shaped second inclined wall portion 25B on the side away from the predetermined ink roller 41, and a bottom wall portion 25C that connects the lower end of the first inclined wall portion 25A and the lower end of the second inclined wall portion 25B and is curved into a substantially U-shape that is convex downward. The first inclined wall portion 25A includes a linear upper wall portion 25a to which the blade 22 is attached, and a linear lower wall portion 25b that extends from the lower end of the upper wall portion 25a to the bottom wall portion 25C. The upper wall portion 25a is inclined relative to the lower wall portion 25b in a direction approaching the predetermined ink roller 41. When the tip of the blade 22 is in contact with the outer circumferential surface of the predetermined ink roller 41, the upper end of the upper wall portion 25a is configured to be separated from the outer circumferential portion of the predetermined ink roller 41.

[0025] The blade portion 22A of the blade 22 configured as described above is configured to come into contact with the outer circumferential surface of the specified ink roller 41 in a direction intersecting the outer circumferential surface of the specified ink roller 41, that is, in an inclined position with the tip side facing diagonally upward. When scraping off the ink, the specified ink roller 41 is rotated counterclockwise so that the ink E on the specified ink roller 41 moves toward the blade 22 at the contact position of the blade portion 22A of the blade 22, as shown in Fig. 3. This allows the ink E on the specified ink roller 41 to be scraped off by the blade portion 22A of the blade 22. The ink E scraped off by the blade portion 22A moves by its own weight toward the collection container 25 along the upper surface (front surface) 22a of the blade portion 22A, which is inclined so that the upper end side is located closer to the specified ink roller 41 (facing diagonally upward to the right in Fig. 3).

[0026] The printing press is equipped with a control unit F (see FIG. 3) that controls the change in position of the blade 22 and the rotation of the predetermined ink roller 41. The control unit F changes the position of the blade 22 from the contact position to the separated position, and outputs an instruction signal to a motor (not shown) that drives and rotates the predetermined ink roller 41 so as to rotate the predetermined ink roller 41 clockwise, which is the opposite direction to the counterclockwise direction, in accordance with the change in position of the blade 22. The counterclockwise direction corresponds to the first rotation direction of the present invention, and the clockwise direction corresponds to the second rotation direction of the present invention.

[0027] In addition, the control unit F stops the rotation of the designated ink roller 41 after changing the position of the blade 22 to the contact position to scrape off the ink, and then changes the position of the blade 22 from the contact position to the separation position after maintaining the stop for a predetermined time (see FIG. 4). As described above, by stopping the rotation of the designated ink roller 41 for a predetermined time, the ink on the blade 22, particularly at the tip 22F, gradually flows downward. As a result, when the blade 22 is changed from the contact position to the separation position after the predetermined time, stringing is unlikely to occur between the tip 22F of the blade 22 and the outer circumferential surface 41A of the designated ink roller 41, or, even if it does occur, the amount of ink that becomes stringy can be reduced. The suitable value of the predetermined time (the time for which the rotation of the designated ink roller 41 is maintained stopped) varies depending on the viscosity of the ink. Generally, UV ink has a higher viscosity and a lower fluidity than oil-based ink, so the predetermined time needs to be longer. For this reason, if UV ink is used, it is preferable to set it to about 10 seconds. In addition, the specified time (stop time) of a specified ink roller 41 may be configured to be able to be set to any time, for example, the stop time for UV ink may be set to 10 seconds, and the stop time for oil-based ink may be set to a time shorter than 10 seconds.

[0028] As a result of an experiment conducted by the inventor of the present application, it was found that the separation distance L (see FIG. 4) between the tip 22F of the blade 22 and the outer peripheral surface 41A of the predetermined ink roller 41 at the separation position of the blade 22 is preferably set to any value between 0.5 mm and 3.0 mm, and more preferably set to about 2.0 mm. In this embodiment, the separation distance L is set to 2.0 mm. The separation distance L is a distance at which the ink E in a stringy state between the tip 22F of the blade 22 and the outer peripheral surface 41A of the predetermined ink roller 41 can be held as shown in FIG. 4 without drooping (see FIG. 6). FIG. 4 shows an example of a state in which the ink E is held in a substantially linear manner between the blade 22 and the predetermined ink roller 41.

[0029] Next, the adjustment of the ink film thickness by scraping off the ink E on the predetermined ink roller 41 with the blade 22 will be described.

[0030] By pressing an ink scraping button or switch (not shown), the control unit F outputs a signal to the air cylinder 23 to extend the air cylinder 23 in order to move the blade 22, which is located at the separation position in FIG. 2, to the contact position. The extension of the air cylinder 23 rotates the collection container 25 clockwise to position the blade 22 at the contact position where it contacts the outer circumferential surface 41A of the predetermined ink roller 41 rotating counterclockwise (see FIG. 3). FIG. 3 shows a state in which the ink E moving toward the blade 22 is scraped off and collected in the collection container 25. When the blade 22 scrapes off the ink E and the film thickness adjustment is completed, the control unit F stops the rotation of the predetermined ink roller 41 while the blade 22 is located at the contact position. The stop is maintained for a predetermined time (for example, 10 seconds in the case of UV ink). When a predetermined time has elapsed since the stop, the control unit F moves the blade 22 from the contact position to the separation position (see FIG. 4). When the blade 22 is located at the separated position, the control unit F outputs an instruction signal to the motor that drives and rotates the designated ink roller 41 so as to rotate the designated ink roller 41 in a clockwise direction opposite to the counterclockwise direction. Note that the amount of clockwise rotation of the designated ink roller 41 at this time may be equal to or greater than the rotation angle required for the stringy ink to be wound up by the designated ink roller 41. For example, it may be equal to or greater than 30°.

[0031] As described above, by rotating the predetermined ink roller 41 clockwise, which is opposite to the counterclockwise direction, the ink E forming the stringiness generated between the tip 22F of the blade 22 and the outer peripheral surface 41A of the predetermined ink roller 41 is pulled by the predetermined ink roller 41 and moves so as to be taken up by the predetermined ink roller 41 (see FIG. 5). As a result, stringiness is unlikely to occur between the tip 22F of the blade 22 and the outer peripheral surface 41A of the predetermined ink roller 41, or even if it does occur, it is quickly eliminated, so that it is possible to prevent the ink E from dropping out of the recovery container 25 from between the tip 22F of the blade 22 and the outer peripheral surface 41A of the predetermined ink roller 41, or from wrapping around and adhering to the back surface 22c (see FIG. 5) of the cutting edge 22A of the blade 22.

[0032] In this embodiment, the specified ink roller 41 is rotated clockwise, which is the opposite direction to the counterclockwise direction, after the blade 22 moves to the separated position, but the rotation of the specified ink roller 41 in the opposite direction may also be started when the blade 22 starts to move to the separated position (simultaneous with the start), or at any position between when the blade 22 starts to move to the separated position and when it is positioned at the separated position.

[0033] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0034] In the above embodiment, the position change of the blade 22 and the rotation of the specified ink roller 41 are controlled by the control unit F so as to prevent stringing from occurring between the tip 22F of the blade 22 and the outer peripheral surface 41A of the specified ink roller 41 when scraping off the ink to adjust the film thickness of the ink on the specified ink roller 41. However, even when performing cleaning work by supplying cleaning liquid to the ink roller group 4 using the cleaning nozzle 21 shown in Figure 2, the position change of the blade 22 and the rotation of the specified ink roller 41 may be controlled by the control unit F so as to prevent stringing from occurring between the tip 22F of the blade 22 and the outer peripheral surface 41A of the specified ink roller 41.

[0035] In addition, in the above embodiment, the ink is scraped off by the ink roller 41 which is the second from the bottom on the left end of the ink roller group 4, but the ink may be scraped off by another ink roller in the ink roller group 4.

[0036] In the above embodiment, the position of the blade 22 is changed by rotating the collection container 25. However, the position of the blade 22 may be changed by linearly sliding the collection container 25.

[0037] In the above embodiment, the cutting edge 22A of the blade 22 is formed in a flat plate shape, but it may be formed in a curved shape. [Explanation of symbols]

[0038] 1...plate cylinder, 2...blanket cylinder, 3...impression cylinder, 4...ink roller group, 5...printing unit, 6...transfer cylinder, 7...feed cylinder, 8...feeder board, 9...mouth plate, 10...swing arm, 11...first delivery cylinder, 12...second delivery cylinder, 13, 14...sprocket, 15...chain, 16...varnish plate cylinder, 17...ink fountain, 18...ink fountain roller, 19...roller, 20...tipping roller, 21...cleaning nozzle, 22...blade, 22A...blade portion, 22B...support portion, 22F...tip, 22a...upper surface ( surface), 22b...inclined surface, 22c...rear surface, 23...air cylinder, 23A...piston rod, 24...arm, 25...collection container, 25A...first inclined wall portion, 25B...second inclined wall portion, 25C...bottom wall portion, 25a...upper wall portion, 25b...lower wall portion, 26...screw, 27...string puller, 41...predetermined ink roller, 41A...outer peripheral surface, A...paper feed portion, B...printing portion, C...surface treatment portion, D...paper discharge portion, E...ink, F...control portion, K...ink fountain key, L...separation distance, S,T,R...arrows, X...axis center

Claims

1. the ink roller group has a plurality of ink rollers for sending ink from an ink fountain to a plate cylinder, the ink roller group has a blade for scraping off ink on a predetermined ink roller among the plurality of ink rollers, and a recovery container for recovering the ink scraped off by the blade, the blade is configured to be movable between a contact position where it contacts the predetermined ink roller to scrape off the ink on the predetermined ink roller and a separation position where it is separated from the predetermined ink roller, the predetermined ink roller is configured to rotate in a first rotation direction when the blade scrapes off the ink on the predetermined ink roller, and the ink roller group has a control unit for controlling the change in position of the blade and the rotation of the predetermined ink roller, The control unit changes the position of the blade from a contact position to a separated position, and rotates the blade in a second rotation direction opposite to the first rotation direction, which is the direction in which the blade scrapes the specified ink roller.

2. 2. The printing press according to claim 1, wherein the blade is configured to contact the specified ink roller in an inclined position with its tip facing diagonally upward at the contact position, and the control unit changes the position of the blade to the contact position to scrape off the ink, then stops the rotation of the specified ink roller in the first rotation direction and maintains the stop for a specified period of time before changing the position of the blade from the contact position to the separated position.

3. 3. A printing press as claimed in claim 1, wherein the distance between the tip of the blade and the outer peripheral surface of the specified ink roller at the separated position of the blade is set to a distance that allows ink to be held between the blade and the specified ink roller without dripping.

4. 4. The printing press according to claim 3, wherein the separation distance is set to any value between 0.5 mm and 3.0 mm.

Images