Printing machine

Abstract

To provide a printing machine that is excellent in accuracy in registering front and rear sides in two-sided printing.SOLUTION: The printing machine comprises a processing cylinder that conveys a sheet and passes the sheet on a printing position, and an inversion path on which a printed sheet is received from the processing cylinder, and front and rear sides of the sheet are inverted and then the sheet is delivered to the processing cylinder. The inversion path includes inverting means that receives a paper bottom of a sheet from a cylinder positioned at a direct upstream side thereof and delivers the sheet to a cylinder positioned at a direct downstream side, with the received paper bottom as a paper head, to invert the sheet, and a plurality of conveying cylinders, arranged at a downstream side of the inverting means on the inversion path, which convey the sheet while holding a paper head of the sheet. A singly-driven conveying cylinder, which is a conveying cylinder arranged at a downstream side of the inverting means on the inversion path, is singly driven by a singly driving source that drives only the singly-driven conveying cylinder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a printing press capable of double-sided printing on sheets. [Background technology]

[0002] Printing presses capable of double-sided printing on sheets have been known for some time (see Patent Document 1). As shown in Fig. 6, this printing press 500 includes a processing drum 501 that transports the sheets and passes them through a printing position PP1, and a reversing path 510 that receives the printed sheets from the processing drum 501, turns the sheets over, and then passes them back to the processing drum 501.

[0003] The reversing path 510 has a reversing transfer drum 511 that receives the sheet from the processing drum 501, a reversing drum 512 that receives the tail end of the sheet (the downstream end in the conveying direction) from the reversing transfer drum 511 and passes the tail end as the head end (the upstream end in the conveying direction) to invert the sheet, and a printing-side transfer drum 513 that passes the sheet received from the reversing drum 512 to the processing drum 501. Each of these drums 511, 512, 513 has a gripper that grips the sheet.

[0004] In this reversing path, between the time when the reversing transfer drum 511 receives the sheet from the processing drum 501 and the time when it passes the sheet to the reversing drum 512, the reversing transfer drum 511 accelerates or decelerates its rotational speed according to the top and bottom size of the sheet being transported (the size of the sheet in the transport direction), so that the gripper of the reversing drum 512 can grip the tail end of the sheet according to the top and bottom size of the sheet being transported. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6899658 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, if the load on the sheet transported to the reversing transfer drum 511 increases due to acceleration or deceleration of the rotational speed of the reversing transfer drum 511, the sheet may become loose or the sheet may slip out of the gripper of the reversing transfer drum 511 slightly, which may cause other problems.

[0007] When such loosening of the sheet or slight slippage of the gripper claws occurs, the position of the tail end of the sheet on the reversing transfer drum 511 changes, causing the position of the tail end of the sheet gripped by the grippers of the reversing drum 512 to deviate from the designed position. In this case, the position of the tail end of the sheet not held by the grippers, etc., on the reversing transfer drum 511 is likely to be more displaced than the head of the sheet held by the grippers of the reversing transfer drum 511.

[0008] This deviation causes the position of the sheet delivered from the reversing path 510 on the processing drum 501 to deviate from the designed position, resulting in deviation of the positions of the printed images on the front and back of the sheet (front and back register) and a decrease in print quality.

[0009] Therefore, an object of the present invention is to provide a printing press that has good front-to-back register accuracy in double-sided printing. [Means for solving the problem]

[0010] The printing press of the present invention comprises: A printing press capable of performing double-sided printing on a sheet while transporting the sheet by a plurality of cylinders, a processing cylinder for transporting the sheet through a printing position; a reversing path that receives the printed sheet from the processing cylinder, turns the sheet over, and then passes it to the processing cylinder; The reversal path is a turnover means for receiving the trailing edge of the sheet from a drum positioned immediately upstream and passing the received trailing edge as the leading edge of the sheet to a drum positioned immediately downstream, thereby turning over the sheet; a plurality of conveying drums that are disposed downstream of the reversing means in the reversing path and that hold and convey the paper heads of the sheets, The independently driven transport cylinder, which is the transport cylinder arranged downstream of the reversing means in the reversing path, is independently driven by an independently driven source that drives only the independently driven transport cylinder.

[0011] In this way, by placing a cylinder (single-drive conveying cylinder) that accelerates and decelerates its rotational speed according to the top and bottom size of the sheet being conveyed in a conveying path made up of multiple conveying cylinders that pass the paper head downstream of the reversing means, deviation of the sheet from its designed position on each conveying cylinder, and deviation of the sheet from its designed position on the processing cylinder that receives the sheet from the reversing path are each reduced, thereby improving the accuracy of front and back registration when printing on both sides.

[0012] Further, in the printing machine, The independently driven transport drum may be arranged immediately downstream of the reversing means, and may deliver the sheet at a position opposite the position where the sheet is received from the reversing means, across the center of rotation of the independently driven transport drum.

[0013] In this way, by making the rotational distance of the independently driven conveying drum from the receiving position of the sheet from the inverting means to the transfer position of the sheet to the downstream drum approximately the same as the rotational distance of the independently driven conveying drum from the transfer position to the receiving position, acceleration (positive acceleration and negative acceleration) can be suppressed when adjusting the rotational speed in accordance with changes in the top and bottom size of the sheet being conveyed.

[0014] Further, in the printing machine, The independently driven transport cylinder may have an outer peripheral surface that is treated to prevent scratches.

[0015] When the rotational speed of the independently driven conveying drum is accelerated or decelerated in accordance with the top and bottom size of the sheet being conveyed, friction occurs between the drum and the adjacent drum downstream or the sheet being conveyed by the drum. However, by applying a scratch-resistant treatment to the outer peripheral surface of the independently driven conveying drum, the occurrence of scratches caused by the friction on the outer peripheral surface of the adjacent drum or on the surface of the sheet being conveyed by the drum is suppressed. [Effects of the Invention]

[0016] As described above, according to the present invention, a printing press with good front-to-back register accuracy in double-sided printing can be provided. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a printing press according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram for explaining the processing cylinder and the reversing path in the printing press. [Figure 3] FIG. 3 is a view of the independently driven conveying drum and the independently driven motor as viewed from a direction perpendicular to the direction of the central axis of rotation. [Figure 4] FIG. 4 is a view of the independently driven conveying cylinder as seen from the direction of the central axis of rotation. [Figure 5] FIG. 5 is a diagram for explaining the control of the rotation speed of the independently driven transport cylinder. [Figure 6] FIG. 6 is a schematic diagram showing the configuration of a conventional printing press. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, one embodiment of the present invention will be described with reference to FIGS.

[0019] The printing press of this embodiment is a printing press capable of double-sided printing on sheets while transporting the sheets using multiple cylinders. As shown in Fig. 1, this printing press P includes a paper feed unit 1 that feeds sheets, a printing unit 2 that receives the sheets fed from the paper feed unit 1 and prints on the sheets, and a paper discharge unit 3 that discharges and stores the sheets printed in the printing unit 2. The printing press P also includes two drive sources (a main motor M1 and an independent drive motor (independent drive source) M2).

[0020] The paper supply unit 1 supplies (feeds) stocked paper sheets to the printing unit 2. The paper supply unit 1 includes a paper supply tray 11 on which paper sheets are stocked, and a feeder 12 that supplies (feeds) the paper sheets from the paper supply tray 11 to the printing unit 2 in sequence.

[0021] Specifically, in the paper supply unit 1, the paper supply tray 11 stores stacked paper sheets, and the feeder 12 supplies the paper sheets stacked on the paper supply tray 11 to the printing unit 2 in a predetermined supply cycle, starting from the top, through the feeder board 121. In the paper supply unit 1, the supply cycle of paper sheets to the printing unit 2 during double-sided printing is twice the supply cycle to the printing unit 2 during single-sided printing.

[0022] The printing unit 2 performs double-sided printing or single-sided printing on the sheets supplied from the paper supply unit 1. The printing unit 2 includes a processing drum 22 that transports the sheets and passes them through a printing position PP, and an inversion path 25 that receives the sheets that have been printed on one side from the processing drum 22, inverts the sheets, and then passes them to the processing drum 22.

[0023] Specifically, printing unit 2 includes a swing 21 that receives and transports sheets from feeder 12, a transfer drum 255 that receives and transports sheets from swing 21, a processing drum 22 that receives and transports sheets from transfer drum 255 while passing through a printing position PP, and a reversing path 25 that reverses the sheets received from processing drum 22 and returns them to processing drum 22. Printing unit 2 also includes a print processing unit 23 that is disposed opposite the outer peripheral surface of processing drum 22 and prints on sheets being transported by processing drum 22. The position where print processing unit 23 and processing drum 22 face each other is the printing position PP.

[0024] The swing 21 is disposed at the tip end of the feeder board 121 and transports sheets from the feeder board 121 to the transfer drum 255. The swing 21 has a gripper 21g at its tip end, which is composed of a claw base and a claw, and swings around a swing axis 211. At the tip end (gripper arrangement position) of the swing 21, multiple grippers 21g are disposed at intervals in the direction of the swing axis. When the swing 21 receives a sheet, each gripper 21g grips (squeezes) the sheet with the claw base and claw, and when the swing 21 passes the sheet, the gap between the claw base and claw opens, releasing the gripped sheet.

[0025] The transfer drum 255 is disposed adjacent to the swing 21 and rotates around a rotation center C1 to transport sheets from the swing 21 to the processing drum 22. As shown in FIG. 2 , the transfer drum 255 of this embodiment is disposed adjacent to the processing drum 22 so that the rotation center C1 of the transfer drum 255 is located below the rotation center C2 of the processing drum 22.

[0026] Furthermore, the transfer drum 255 of this embodiment also serves as the most downstream drum among the multiple drums included in the reversing path 25. That is, the transfer drum 255 is included in the sheet transport path from the paper feed unit 1 to the processing drum 22, and is also included in the reversing path 25. Therefore, the transfer drum 255 can also transport (transfer) the sheet transported along the reversing path 25 to the processing drum 22.

[0027] Specifically, the transfer drum 255 is provided with grippers 255g at two locations in the circumferential direction. At each location of the grippers 255g in the circumferential direction (hereinafter simply referred to as "gripper location locations"), multiple grippers 255g are arranged at intervals in the direction of the central axis of rotation of the transfer drum 255. In the transfer drum 255 of this embodiment, the grippers 255g at the two locations are arranged at equal intervals in the circumferential direction. The configuration of each gripper 255g is the same as that of the gripper 21g of the swing 21. The transfer drum 255 is configured so that the temperature of the outer periphery can be adjusted.

[0028] The transfer cylinder 255 is a so-called double cylinder that has grippers 255g at two circumferential locations and has a diameter twice that of a reference cylinder (hereinafter referred to as a "diameter reference cylinder"). Here, the diameter reference cylinder is the cylinder with the smallest diameter among the multiple cylinders that transport sheets in the printing press P. In the printing press P of this embodiment, the diameter reference cylinders are the first to third delivery cylinders 321 to 323, etc.

[0029] The processing drum 22 is disposed adjacent to the transfer drum 255, and while rotating about a rotation center C2, transports the paper sheet from the transfer drum 255 to the paper discharge section 3 (specifically, the first paper discharge drum 321) or the reversal path 25 (specifically, the receiving drum 251). The processing drum 22 transports the paper sheet so that it passes through a position (printing position) PP opposite the print processing section 23.

[0030] Specifically, the processing cylinder 22 is provided with grippers 22g at three locations in the circumferential direction. At each gripper location, multiple grippers 22g are arranged at intervals in the direction of the central axis of rotation of the processing cylinder 22. In the processing cylinder 22 of this embodiment, the three grippers 22g are arranged at equal intervals in the circumferential direction. The configuration of each gripper 22g is the same as that of the gripper 21g of the swing 21.

[0031] The processing drum 22 has a large number of suction holes arranged on its outer circumferential surface, which attracts almost the entire area of ​​the sheet to the outer circumferential surface during transport, thereby preventing the sheet from floating from the outer circumferential surface during transport.

[0032] The processing cylinder 22 is a so-called triple cylinder, which has grippers 22g at three locations in the circumferential direction and has a diameter three times the diameter of the diameter reference cylinder.

[0033] The print processing unit 23 is a device that prints (performs a print process) on sheets being transported by the processing drum 22, and the print processing unit 23 in this embodiment is an inkjet device. The print processing unit 23 is arranged at the printing position PP with the inkjet head facing the outer circumferential surface of the processing drum 22. Note that the print processing unit 23 is not limited to an inkjet device.

[0034] The reversing path 25 is a sheet transport path comprised of a reversing means (for example, a reversing swing 253 or a reversing drum) and multiple drums, and it inverts the sheet received from the processing drum 22 while being transported, and then passes it to the processing drum 22. This reversing path 25 includes a reversing means that receives the tail end of the sheet (the rear end of the sheet in the transport direction) from a drum located immediately upstream and passes the received tail end as the head end (the leading end of the sheet in the transport direction) to a drum located immediately downstream, thereby inverting the sheet, and multiple transport drums 250 that are arranged downstream of the reversing means on the reversing path 25 and that hold and transport the head end of the sheet. The reversing means in this embodiment is the reversing swing 253.

[0035] Specifically, the reversing path 25 includes a receiving drum 251 that receives the sheet from the processing drum 22, a reversing swing 253 that receives the sheet from the receiving drum 251 and reversing it, an independently driven conveying drum 254 that is a conveying drum 250 arranged downstream of the reversing swing 253 in the reversing path 25, and a transfer drum 255 that is a conveying drum 250 that receives the sheet from the independently driven conveying drum 254. That is, the multiple conveying drums 250 in the reversing path 25 of this embodiment are the independently driven conveying drum 254 and the transfer drum 255.

[0036] The receiving drum 251 is disposed adjacent to the processing drum 22, and rotates around a rotation center C3 while transporting sheets from the processing drum 22 to the reversing swing 253. In this embodiment, the receiving drum 251 is disposed adjacent to the processing drum 22 so that the rotation center C3 of the receiving drum 251 is lower than the rotation center C2 of the processing drum 22 and lower than the rotation center C1 of the transfer drum 255.

[0037] In addition, when viewed from the direction of the central axis of rotation of the processing drum 22, the receiving drum 251 and the transfer drum 255 are positioned relative to the processing drum 22 so that the angle α formed by the first imaginary line L1 connecting the rotation center C2 of the processing drum 22 and the rotation center C3 of the receiving drum 251 and the second imaginary line L2 connecting the rotation center C2 of the processing drum 22 and the rotation center C1 of the transfer drum 255 is 90° or less.

[0038] Specifically, the receiving cylinder 251 is provided with a gripper 251g at one location in the circumferential direction. At the gripper arrangement position, multiple grippers 251g are arranged at intervals in the direction of the central axis of rotation of the receiving cylinder 251. The configuration of each gripper 251g is the same as that of the gripper 21g of the swing 21. In addition, the receiving cylinder 251 has a diameter twice the diameter of the diameter reference cylinder.

[0039] The receiving drum 251 has an outer circumferential guide surface 251a that guides the paper sheets in a range from the gripper arrangement position in the circumferential direction as viewed from the direction of the central axis of rotation to a position downstream by a predetermined angle. In this embodiment, the predetermined angle is 145 degrees. Meanwhile, the outer circumferential surface of the receiving drum 251 in the circumferential direction other than the outer circumferential guide surface 251a has a smaller diameter than the outer circumferential guide surface 251a. The range downstream of the outer circumferential guide surface 251a is a smaller-diameter outer circumferential surface 251b.

[0040] This guide outer peripheral surface 251a is divided into a plurality of parts at intervals in the direction of the central axis of rotation of the receiving drum 251. The tip end of the reversing swing 253 (more specifically, the gripper 253g) fits between these divided outer peripheral surfaces (divided guide outer peripheral surfaces 251a), thereby avoiding collision between the receiving drum 251 and the reversing swing 253.

[0041] The reversing swing 253 is disposed adjacent to the receiving drum 251 and transports sheets from the receiving drum 251 to the independently driven transport drum 254. This reversing swing 253 has the same configuration as the above-described swing 21 that receives sheets from the feeder 12. That is, the reversing swing 253 has a gripper 253g at its tip and swings around a swing shaft 2531. At the tip (gripper arrangement position) of the reversing swing 253, a plurality of grippers 253g are arranged at intervals in the direction of the swing shaft. The configuration of each gripper 253g is the same as the gripper 21g of the swing 21. The reversing swing 253 of this embodiment repeats a predetermined swinging motion.

[0042] In this embodiment, the reversing swing 253 is disposed so that the swing shaft 2531 is located below the rotation center C3 of the receiving drum 251. The reversing swing 253 is also disposed so that the swing shaft 2531 is located on the opposite side to the processing drum 22 with respect to a third imaginary line L3 connecting the rotation center C3 of the receiving drum 251 and the rotation center C4 of the independently driven transfer drum 254. This reduces the swing range of the reversing swing 253.

[0043] The reversing swing 253 can change the phase of its swinging motion in accordance with differences in the position of the tail end of a sheet being conveyed, which is based on differences in the top-bottom size (size of the sheet in the conveying direction) of the sheet received from the receiving drum 251. Specifically, a phase adjustment mechanism that adjusts the phase of the swinging motion of the reversing swing 253 is disposed midway along the transmission path (power transmission mechanism) that transmits power (driving force) from the main motor M1 to the reversing swing 253. This phase adjustment mechanism has a clutch or the like, and adjusts the phase of the swinging motion of the reversing swing 253 by transmitting and cutting off power using the clutch or the like.

[0044] The reversing swing 253 configured as described above rotates counterclockwise in FIG. 1 to hold the trailing edge of the sheet on the outer circumferential guide surface 251a of the receiving drum 251 with the gripper 253g, and then rotates clockwise to transfer the trailing edge to the independently driven conveying drum 254 as the leading edge.

[0045] The independently driven transport drum 254 is disposed adjacent to the reversing swing 253 and rotates about a rotation center C4 to transport sheets from the reversing swing 253 to the transfer drum 255. The independently driven transport drum 254 is disposed so that its rotation center C4 is located on the opposite side to the processing drum 22 with respect to a fourth imaginary line L4 connecting the rotation center C3 of the receiving drum 251 and the rotation center C1 of the transfer drum 255. The independently driven transport drum 254 is disposed so that its rotation center C4 is located above the rotation center C3 of the receiving drum 251 and below the rotation center C1 of the transfer drum 255.

[0046] 3 and 4, the independently driven transport cylinder 254 is provided with a gripper 254g at one location in the circumferential direction. At the gripper arrangement position, multiple grippers 254g are arranged at intervals in the direction of the central axis of rotation of the independently driven transport cylinder 254. The configuration of each gripper 254g is similar to that of the gripper 21g of the swing 21.

[0047] This independently driven conveying cylinder 254 is a so-called single cylinder that has a gripper 254g at one location in the circumferential direction and has a diameter substantially the same as the diameter of the diameter reference cylinder.

[0048] In this embodiment, the independently driven conveying drum 254 receives a sheet from the reversing swing 253 at a position (receiving position) P1, and delivers the sheet to the delivery drum 255 at a position (delivery position) P2 on the opposite side of the rotation center C4 of the independently driven conveying drum 254. In other words, the independently driven conveying drum 254's sheet receiving position P1 and sheet delivery position P2 are spaced apart by approximately 180° in the circumferential direction.

[0049] The independently driven conveying cylinder 254 is a so-called single cylinder, but in order to avoid collision with the gripper 253g of the reverse swing 253, the outer peripheral surface 254a of the independently driven conveying cylinder 254 is formed with a smaller diameter than the diameter of the diameter reference cylinder.

[0050] The outer periphery (outer periphery) of the independently driven transport cylinder 254 may be configured to have circumferential grooves for collision avoidance at positions corresponding to the grippers 253g of the reverse swing 253 in the rotation axis direction.

[0051] The independently driven conveying drum 254 is independently driven by an independently driven motor M2, separate from the machine motor M1 that drives the other conveying components. This independently driven motor increases or decreases the rotational speed of the independently driven conveying drum 254. However, because the rotational speeds (circumferential speeds) of the other drums are constant, a difference in peripheral speed occurs between the outer peripheral surface of the drum that transfers the sheet (in this embodiment, the transfer drum 255) and the outer peripheral surface 254a of the independently driven conveying drum 254. This can cause friction between the sheet being conveyed to the drum that transfers the sheet (in this embodiment, the transfer drum 255) and the outer peripheral surface 254a of the independently driven conveying drum 254. For this reason, the outer peripheral surface 254a of the independently driven conveying drum 254 in this embodiment is treated with a scratch-resistant coating by attaching a raised cloth (velvet) to prevent scratches on the printed surface or the sheet itself due to the friction. In other words, the independently driven conveying drum 254 has an outer peripheral surface that is treated with a scratch-resistant coating. The details of the independent drive by the independent drive motor M2 will be described later.

[0052] In the printing unit 2 configured as described above, a region (bag area) S is formed that is surrounded by the processing drum 22 and the reversing path 25 when viewed from the direction of the central axis of rotation of the processing drum 22 (see the area indicated by dots in FIG. 2). Within this bag area S, the outer peripheral surface of the processing drum 22 is always exposed and not covered by the sheets, even during sheet transport, making the outer peripheral surface of the processing drum 22 easily accessible for maintenance, etc. Also, an accessory device that directly acts on the outer peripheral surface of the processing drum 22 can be installed. Note that in the printing press P of this embodiment, the receiving drum 251 has a small-diameter outer peripheral surface 251b on its outer peripheral surface. By adjusting the rotational angle position of the receiving drum 251 so that the small-diameter outer peripheral surface 251b defines the bag area S, the bag area S can be further enlarged.

[0053] The paper discharge unit 3 includes a paper discharge tray 31 for storing sheets printed on one side or both sides in the printing unit 2, and a transport path 32 for transporting the sheets printed in the printing unit 2 to the paper discharge tray 31.

[0054] The conveying path 32 includes a first discharge drum 321 that receives and conveys sheets from the processing drum 22, a second discharge drum 322 that receives and conveys sheets from the first discharge drum 321, a third discharge drum 323 that receives and conveys sheets from the second discharge drum 322, a fourth discharge drum 324 that receives and conveys sheets from the third discharge drum 323, and a chain delivery 325 that receives and conveys sheets from the fourth discharge drum 324.

[0055] The first delivery drum 321 is disposed upstream of the receiving drum 251 at a position where it can receive the paper sheets from the processing drum 22 .

[0056] Each of the first paper discharge drum 321, the second paper discharge drum 322, and the third paper discharge drum 323 is a so-called single drum, in which multiple grippers 321g, 322g, and 323g are arranged at intervals in the direction of the rotation axis, are arranged at one location in the circumferential direction, and have the same diameter as the diameter of the diameter reference drum.

[0057] The fourth delivery drum 324 is a so-called double drum, in which a plurality of grippers 324g are arranged at two locations in the circumferential direction with a gap in the direction of the central axis of rotation, and the diameter of the fourth delivery drum 324 is twice the diameter of the diameter reference drum.

[0058] The chain delivery 325 is disposed adjacent to the fourth discharge drum 324 and transports the paper sheets from the fourth discharge drum 324 to the paper delivery tray 31. Specifically, the chain delivery 325 is a chain-type transport device that transports the paper sheets received from the fourth discharge drum 324, and is provided with discharge grippers 325g at multiple locations (three locations in the example shown in FIG. 1) on an endlessly arranged chain (endless chain). At each location of the discharge grippers 325g in the circumferential direction of the endless chain, the multiple discharge grippers 325g are arranged at intervals in the direction of the rotational axis of a sprocket (not shown) that drives the chain. The three discharge grippers 325g are arranged at equal intervals in the circumferential direction of the endless chain.

[0059] The main machine motor M1 drives the transport members (members involved in transporting sheets) except for the independently driven transport drum 254. The transport members in the printing press P of this embodiment include the swing 21, processing drum 22, receiving drum 251, reversing swing 253, transfer drum 255, first delivery drum 321, second delivery drum 322, third delivery drum 323, fourth delivery drum 324, and chain delivery 325, and these transport members 21, 22, 251, 253, 255, 321 to 325, etc. are connected to each other by gears or the like, and are driven synchronously by the power output from the main machine motor M1. As a result, the multiple cylinders 22, 251, 255, 321 to 324, excluding the independently driven conveying cylinder 254, rotate so that they all have the same peripheral speed (speed in the circumferential direction), and the swing 21 and the reverse swing 253 oscillate so as to match the phases of the multiple cylinders 22, 251, 255, 321 to 324.

[0060] For example, the gear of the output shaft of the motor M1 of this machine is engaged only with the gear of the processing cylinder 22, and the other conveying members 21, 251, 253, 255, 321 to 325 other than the processing cylinder 22 receive power directly or indirectly from the gear of the processing cylinder 22.

[0061] The independently driven motor M2 drives the independently driven conveying drum 254 located immediately downstream of the reversing swing 253. This independently driven motor M2 increases or decreases the rotation speed of the independently driven conveying drum 254 in accordance with a change in the phase of the oscillation of the reversing swing 253 due to differences in the top-bottom size of the conveyed sheets. In other words, the circumferential speed of the independently driven conveying drum 254 is increased or decreased relative to the circumferential speeds of the multiple drums 22, 251, 255, 321-324 excluding the independently driven conveying drum 254. The specific increase or decrease in the rotation speed will be described with reference to FIG. 5.

[0062] In Figure 5, t0 is the time when the gripper 254g of the individually driven conveying drum 254 receives the head of the sheet from the reversing swing 253 (i.e., the gripper 254g is located at the receiving position P1), t1 is the time when the first increase / decrease in the rotational speed of the individually driven conveying drum 254 starts, t2 is the time when the first increase / decrease in the rotational speed of the individually driven conveying drum 254 ends, t3 is the time when the gripper 254g of the individually driven conveying drum 254 passes the head of the sheet to the transfer drum 255 (i.e., the gripper 254g is located at the transfer position P2), t4 is the time when the second increase / decrease in the rotational speed of the individually driven conveying drum 254 starts, t5 is the time when the second increase / decrease in the rotational speed of the individually driven conveying drum 254 ends, and t6 is the time when the gripper 254g of the individually driven conveying drum 254 receives the head of the sheet from the reversing swing 253 again. The independently driven motor drives the independently driven transport drum 254 so as to repeat a cycle from time t0 to time t6.

[0063] When the top-bottom size (length in the conveying direction) of a sheet is the standard size (medium size), the individually driven motor M2 drives the individually driven conveying drum 254 so that the individually driven conveying drum 254 rotates about the rotation center C4 at a constant speed (standard speed) until the position of the gripper 254g moves from receiving position P1 (time t1) through transfer position P2 (time t3) and then to receiving position P1 again (time t6), as shown by the thick line in Figure 5. In other words, the individually driven motor M2 drives the individually driven conveying drum 254 so that the individually driven conveying drum 254 rotates at the standard speed throughout. The peripheral speed of the individually driven conveying drum 254 rotating at the standard speed is the same as the peripheral speeds of the multiple drums 22, 251, 255, 321-324 excluding the individually driven conveying drum 254.

[0064] As a result, at time t0, the gripper 253g of the reversing swing 253 and the gripper 254g of the independently driven conveying drum 254 face each other, and the independently driven conveying drum 254 receives the head of the sheet from the reversing swing 253, and the sheet is conveyed in a state of being wrapped around the outer circumferential surface of the independently driven conveying drum 254. Then, at time t3, the gripper 254g of the independently driven conveying drum 254 and the gripper 255g of the transfer drum 255 face each other, and the head of the sheet is transferred from the independently driven conveying drum 254 to the transfer drum 255.

[0065] Next, when the top and bottom size of the sheet is the maximum size (larger than the standard size), the individual drive motor M2 drives the individually driven transport drum 254 from times t0 to t1, t2 to t4, and t5 to t6 so that the individually driven transport drum 254 rotates at the same standard speed as when transporting a standard size sheet. Then, as shown by the solid line in Figure 5, the individual drive motor M2 gradually increases the rotational speed of the individually driven transport drum 254 from the standard speed starting at time t1, and then drives the individually driven transport drum 254 so that the rotational speed returns to the standard speed at time t2. Furthermore, the individual drive motor M2 gradually decelerates the rotational speed of the individually driven transport drum 254 from the standard speed starting at time t4, and then drives the individually driven transport drum 254 so that the rotational speed returns to the standard speed at time t5.

[0066] Here, when the conveyed sheet is of the maximum size (larger than the standard size), the phase of the oscillation of the reversing swing 253 is delayed when it receives the sheet from the receiving drum 251, so that if the independently driven conveying drum 254 that received the sheet from the reversing swing 253 continues to rotate at the standard speed, when the gripper 255g of the transfer drum 255 reaches the transfer position P2, the gripper 254g of the independently driven conveying drum 254 does not reach the transfer position P2, and the sheet cannot be transferred. Therefore, when the independently driven conveying drum 254 is driven by the independently driven motor M2, the rotation speed is increased and decreased as described above from time t1 to t2 (first speed increase / decrease region), so that when the gripper 255g of the transfer drum 255 reaches the transfer position P2, the gripper 254g of the independently driven conveying drum 254 faces the gripper 255g, and the sheet can be transferred.

[0067] Furthermore, by reversing the change in rotational speed of the independently driven conveying drum 254 from time t4 to t5 (second speed increase / decrease region) to the change in rotational speed from time t1 to t2, the gripper 254g of the independently driven conveying drum 254 can reach the receiving position P1 at the same time that the gripper 253g of the reversing swing 253 reaches the transfer position for the sheet to the independently driven conveying drum 254.

[0068] On the other hand, when the top and bottom size of the sheet is the minimum size (a size smaller than the standard size), the individual drive motor M2 drives the individually driven transport drum 254 from times t0 to t1, t2 to t4, and t5 to t6 so that the individually driven transport drum 254 rotates at the same standard speed as when transporting a standard size sheet. Then, as shown by the dashed line in Figure 5, the individual drive motor M2 drives the individually driven transport drum 254 so that the rotational speed of the individually driven transport drum 254 gradually decreases from the standard speed from time t1, and then returns to the standard speed at time t2. Also, the individual drive motor M2 drives the individually driven transport drum 254 so that the rotational speed of the individually driven transport drum 254 gradually increases from the standard speed from time t4, and then returns to the standard speed at time t5.

[0069] Here, if the sheet being conveyed is of the minimum size (smaller than the standard size), the phase of the oscillation of the reversing swing 253 is advanced when it receives the sheet from the receiving drum 251, so that if the independently driven conveying drum 254 that has received the sheet from the reversing swing 253 continues to rotate at the standard speed, the gripper 254g of the independently driven conveying drum 254 will reach transfer position P2 before the gripper 255g of the transfer drum 255 reaches transfer position P2, making it impossible to transfer the sheet. Therefore, by slowing down and accelerating the rotational speed as described above between times t1 and t2 (first speed increase / decrease region) when the independently driven conveying drum 254 is driven by the independently driven motor M2, the gripper 254g of the independently driven conveying drum 254 will face the gripper 255g of the transfer drum 255 when it reaches transfer position P2, making it possible to transfer the sheet.

[0070] Furthermore, by reversing the change in rotational speed of the independently driven conveying drum 254 from time t4 to t5 (second speed increase / decrease region) to the change in rotational speed from time t1 to t2, the gripper 254g of the independently driven conveying drum 254 can reach the receiving position P1 at the same time that the gripper 253g of the reversing swing 253 reaches the transfer position for the sheet to the independently driven conveying drum 254.

[0071] The outline of the operation of the printing press P configured as above during single-sided printing is as follows.

[0072] Sheets are sequentially supplied from the paper feed unit 1 to the printing unit 2 at a predetermined supply cycle. The sheets supplied to the printing unit 2 are transferred to the transfer drum 255 by the swing 21, and then conveyed in this order to the processing drum 22, the first paper discharge drum 321, the second paper discharge drum 322, the third paper discharge drum 323, the fourth paper discharge drum 324, and the chain delivery 325, and then discharged onto the paper discharge tray 31.

[0073] When a sheet is transported during single-sided printing, as the sheet is transported to the processing drum 22 and passes through the printing position PP, the printing processing unit 23 applies printing processing to one side (the outer surface in the radial direction of the processing drum 22).

[0074] On the other hand, the outline of the operation during double-sided printing is as follows.

[0075] Sheets are sequentially supplied from the paper supply unit 1 to the printing unit 2 at a supply cycle twice that of simplex printing. The sheets supplied to the printing unit 2 are transferred to the transfer cylinder 255 by the swing 21, and then conveyed in this order by the processing cylinder 22, the receiving cylinder 251, the reversing swing 253, the independently driven conveying cylinder 254, and the transfer cylinder 255, and are then transferred from the transfer cylinder 255 to the processing cylinder 22 again.

[0076] Next, the sheet of paper (the sheet of paper after being transported along the reversal path 25) is handed over again from the transfer drum 255 to the processing drum, and is transported from the processing drum 22 to the first paper discharge drum 321, the second paper discharge drum 322, the third paper discharge drum 323, the fourth paper discharge drum 324, and the chain delivery 325 in that order, and is discharged onto the paper discharge tray 31.

[0077] In the conveyance of a sheet during double-sided printing, the sheet passes through the printing position PP during the first conveyance by the processing cylinder 22, and the print processing unit 23 performs printing processing on one side of the sheet.

[0078] The sheet of paper with one side printed is passed from the processing drum 22 to the receiving drum 251 and transported along the reversing path 25 (i.e., it is transported in the order of the receiving drum 251, the reversing swing 253, the independently driven transport drum 254, and the transfer drum 255). Along the way, the sheet is reversed by the reversing swing 253, and the reversed sheet is returned to the processing drum 22.

[0079] Subsequently, when the sheet passes through the printing position PP during the second transport by the processing cylinder 22, the print processing is performed on the other side by the print processing unit 23.

[0080] The above-mentioned printing press P is a printing press P capable of printing on both sides of a sheet while transporting the sheet using multiple cylinders, and is equipped with a processing cylinder 22 that transports the sheet and passes it through the printing position PP, and an inversion path 25 that receives the printed sheet from the processing cylinder 22, inverts the sheet, and then passes it to the processing cylinder 22. The reversing path 25 includes a reversing swing 253 that receives the tail end of a sheet from a drum located immediately upstream (in this embodiment, the receiving drum 251) and passes the received tail end as the head of the sheet to a drum located immediately downstream (in this embodiment, the independently driven conveying drum 254), thereby reversing the sheet, and a plurality of conveying drums 250 that are arranged downstream of the reversing swing 253 in the reversing path 25 and hold and convey the head of the sheet, and the independently driven conveying drum 254, which is a conveying drum 250 located downstream of the reversing swing 253 in the reversing path 25, is independently driven by an independently driven motor (single drive source) M2 that drives only the independently driven conveying drum 254.

[0081] In this way, by arranging a cylinder (single-drive conveying cylinder) 254, which accelerates and decelerates the rotational speed according to the top and bottom size of the sheet being conveyed, in a conveying path formed by multiple conveying cylinders 250 that transfer the paper head downstream of the reversing swing 253, deviation of the sheet from its designed position on each conveying cylinder 250 and deviation of the sheet from its designed position on the processing cylinder 22 that receives the sheet from the reversing path 25 are each reduced, thereby improving the accuracy of front and back registration during double-sided printing.

[0082] In addition, in the printing press P of this embodiment, the independently driven conveying drum 254 is positioned immediately downstream of the reversing swing 253, and the sheet is transferred to the downstream conveying drum 250 (transfer drum 255 in this embodiment) at a transfer position P2 on the opposite side of the rotation center C4 of the independently driven conveying drum 254 from the receiving position P1 where the sheet is received from the reversing swing 253.

[0083] In this way, by making the rotational distance of the independently driven conveying drum 254 from the receiving position P1 where the sheet is received from the reverse swing 253 to the transfer position P2 where the sheet is transferred to the downstream conveying drum 250 (transfer drum 255) approximately the same as the rotational distance of the independently driven conveying drum 254 from the transfer position P2 to the receiving position P1, it is possible to suppress acceleration (positive acceleration and negative acceleration) when adjusting the rotational speed in accordance with changes in the top and bottom size of the sheet being conveyed.

[0084] Specifically, by positioning receiving position P1 opposite transfer position P2 across rotation center C4, the time from time t0 to t3 and the time from time t3 to t6 can be made the same or approximately the same, and the degree of increase or decrease in the rotational speed of independently driven conveying drum 254 (acceleration: the slope of the solid line or dashed line for the mountain-shaped speed change and the valley-shaped speed change in FIG. 5) can be made the same or approximately the same in the first speed increase / decrease region and the second speed increase / decrease region shown in FIG. 5. This makes it possible to make the rotational load on independently driven conveying drum 254 when moving from receiving position P1 to transfer position P2 and the rotational load on independently driven conveying drum 254 when moving from transfer position P2 to receiving position P1 approximately the same, preventing the load during either rotation from becoming too high.

[0085] Furthermore, as described above, by suppressing the acceleration (positive acceleration and negative acceleration) when accelerating and decelerating the rotational speed of the individually driven conveying drum 254 according to the top and bottom size of the sheet, fluttering of the sheet during transport on the individually driven conveying drum 254 is suppressed.

[0086] Furthermore, in the printing press P of this embodiment, the independently driven transport cylinder 254 has an outer peripheral surface that has been subjected to a scratch prevention treatment.

[0087] When the rotational speed of the independently driven conveying drum 254 is accelerated or decelerated in accordance with the top and bottom size of the sheet being conveyed, friction occurs between the adjacent drum (transfer drum) 255 downstream or the sheet being conveyed by the drum (transfer drum) 255. However, by applying an anti-scratch treatment to the outer peripheral surface of the independently driven conveying drum 254, the occurrence of scratches due to the friction on the outer peripheral surface of the adjacent drum (transfer drum) 255 or on the surface of the sheet being conveyed by the drum (transfer drum) 255 is suppressed.

[0088] The printing press of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, or part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, part of the configuration of one embodiment can be deleted.

[0089] In the reversing path 25 of the printing press P in the above embodiment, the conveying member that reverses the sheet is the reversing swing 253, but is not limited to this configuration. The conveying member that reverses the sheet may also be a reversing cylinder.

[0090] Furthermore, in the printing press P of the above embodiment, the reversing path 25 includes the transfer drum 255, but is not limited to this configuration. The reversing path 25 may be configured not to include the transfer drum 255, and to transfer the inverted paper sheet to the processing drum 22 at a position upstream of the transfer drum 255 (opposite the rotation direction of the processing drum 22).

[0091] In addition, in the reversing path 25 of the printing press P in the above embodiment, two conveying cylinders 250 (single-drive conveying cylinder 254, transfer cylinder 255) are arranged downstream of the reversing swing 253, but three or more conveying cylinders 250 may be arranged. In addition, in the reversing path 25 of the printing press P in the above embodiment, one conveying cylinder 250 (receiving cylinder) 251 is arranged upstream of the reversing swing 253, but two or more conveying cylinders 250 may be arranged.

[0092] Furthermore, in the printing press P of the above embodiment, the outer peripheral surface 254a of the independently driven transport drum 254 is protected from scratches by attaching a raised cloth (velveteen), but the protection is not limited to this. For example, glass cloth may be attached. Alternatively, a thin air layer may be formed between the paper sheets and the outer peripheral surface 254a. [Explanation of symbols]

[0093] 1...paper feed unit, 11...paper feed table, 12...feeder, 121...feeder board, 2...printing unit, 21...swing, 21g...gripper, 211...oscillating shaft, 22...processing drum, 22g...gripper, 23...printing processing unit, 25...reversing path, 250...transport drum, 251...receiving drum (transport drum), 251a...guide outer peripheral surface, 251b...small diameter outer peripheral surface, 251g...gripper, 253...reversing swing, 253g...gripper, 2531...oscillating shaft, 254...independently driven transport drum (transport drum), 254a...outer peripheral surface, 254g...gripper, 255...transfer drum, 255g...gripper, 3...paper discharge unit, 31...paper discharge table, 32...transport path, 321...first paper discharge drum, 321g...gripper, 322...second paper discharge Cylinder, 322g...gripper, 323...third delivery cylinder, 323g...gripper, 324...fourth delivery cylinder, 324g...gripper, 325...chain delivery, 325g...delivery gripper, 500...printing press, 501...processing cylinder, 510...reversing path, 511...reversing transfer cylinder, 512...reversing cylinder, 513...printing side transfer cylinder, C1...rotation center of transfer cylinder, C2...rotation center of processing cylinder, C3...rotation center of receiving cylinder, C4...rotation center of independently driven transport cylinder, L1...first imaginary line, L2...second imaginary line, L3...third imaginary line, L4...fourth imaginary line, M1...main machine motor, M2...independent drive motor (independent drive source), P...printing press, P1...receiving position, P2...transfer position, PP, PP1...printing position, S...bag area

Claims

1. A printing press capable of performing double-sided printing on a sheet while transporting the sheet by a plurality of cylinders, a processing cylinder for transporting the sheet through a printing position; a reversing path that receives the printed sheet from the processing cylinder, turns the sheet over, and then passes it to the processing cylinder; The reverse path is a turnover means for receiving the trailing edge of the sheet from a drum positioned immediately upstream and passing the received trailing edge as the leading edge of the sheet to a drum positioned immediately downstream, thereby turning over the sheet; a plurality of conveying drums that are disposed downstream of the reversing means in the reversing path and that hold and convey the paper heads of the sheets, A printing press, wherein the independently driven transport cylinder, which is the transport cylinder arranged downstream of the reversing means in the reversing path, is independently driven by an independently driven source that drives only the independently driven transport cylinder.

2. 2. The printing press according to claim 1, wherein the independently driven transport cylinder is disposed immediately downstream of the reversing means and delivers the sheet at a position opposite to a position where the sheet is received from the reversing means across a rotation center of the independently driven transport cylinder.

3. 3. The printing press according to claim 1, wherein the independently driven transport cylinder has an outer peripheral surface that is treated to prevent scratches.

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