Corrugated cardboard sheet printer

Abstract

To provide a corrugated board sheet printer capable of performing flexographic printing simultaneously on both sides of a corrugated board sheet.SOLUTION: A corrugated board sheet printer 1 comprises: a plurality of first printing units 20 a-f; and at least one second printing unit 40 arranged upstream of the plurality of first printing units 20 a-f. The number of the at least one second printing unit 40 is below the number of the plurality of first printing units 20 a-f. In each of the first printing units 20 a-f, a press cylinder 24 is arranged below a printing cylinder 23. In each of the second printing unit 40, a press cylinder 44 is arranged above a printing cylinder 43.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a printing machine for corrugated board sheets used for flexographic printing on both sides of corrugated board sheets. [Background technology]

[0002] A typical corrugated sheet printing machine used for flexographic printing of corrugated sheets includes multiple printing units with different printing colors, which are arranged in a row along the conveying direction of the corrugated sheet. Each printing unit includes a printing cylinder having a printing plate, a press cylinder that presses the corrugated sheet against the printing cylinder, and an anilox roll that transfers the ink of the color of the printing unit to the printing plate, etc., and the printing cylinder is arranged above the press cylinder, and when the corrugated sheet passes between the press cylinder and the printing cylinder, the ink is transferred from the printing plate to the upper surface of the corrugated sheet (for example, see the printing device 3 shown in FIG. 1 of JP 2017-15335 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication 2017-15335 Summary of the Invention [Problem to be solved by the invention]

[0004] The front side of a cardboard box used for transporting or packing goods is generally printed with the name of the company transporting the goods, the name of the packed goods, the name of the manufacturer of the goods, etc. However, in recent years, there is an increasing need to print not only on the front side of the cardboard box but also on the back side of the cardboard box. For example, a description of the packed goods or a message from the seller to the purchaser of the goods is printed on the back side of the lid of the cardboard box.

[0005] In order to produce a cardboard box that is printed on both the front and back sides, it is necessary to print on both sides of the original cardboard sheet (i.e., the unfolded state of the cardboard box). The above-mentioned conventional flexographic printing machine for cardboard sheets flexographically prints only the top side of the cardboard sheet that is transported. In order to flexographically print on both sides of a cardboard sheet using a conventional printing machine, it was necessary to print one side of the cardboard sheet, then turn the cardboard sheet over and process it in the same printing machine to print the other side of the cardboard sheet.

[0006] To carry out such double-sided printing processing, it is necessary to temporarily change the positions of various devices downstream of the printing machine, such as a creaser device, a slotter device, and a die cutter device, in order to remove the corrugated board sheets printed on only one side from the printing machine. It is also necessary to turn over the corrugated board sheets printed on only one side, stack them, and place them again in the paper feed section of the printing machine. These operations are cumbersome and reduce the productivity of printing and processing of corrugated board sheets.

[0007] The present invention is intended to solve the above problems, and provides a printing machine for corrugated board sheets that can perform flexographic printing on both sides of a corrugated board sheet at once. [Means for solving the problem]

[0008] The first printing machine for corrugated cardboard sheets of the present invention is A printing machine for corrugated cardboard sheets, comprising a plurality of printing units arranged in a row so as to sequentially perform printing processes on the corrugated cardboard sheets, The printing units form a horizontal transport path for the cardboard sheets, Each of the plurality of printing units comprises: a printing cylinder having a printing plate; A press cylinder for pressing a cardboard sheet against the printing cylinder; an anilox roll for transferring ink to the printing plate; Equipped with the plurality of printing units comprises a plurality of first printing units and at least one second printing unit, the number of the at least one second printing unit being equal to or less than the number of the plurality of first printing units; In each first printing unit, the press cylinder is disposed below the printing cylinder, In each second printing unit, the press cylinder is disposed above the printing cylinder; The at least one second printing unit is disposed upstream of the plurality of first printing units in a conveying direction of the cardboard sheet.

[0009] The second printing machine for corrugated cardboard sheets of the present invention is A printing machine for corrugated cardboard sheets, comprising a plurality of printing units arranged in a row so as to sequentially perform printing processes on the corrugated cardboard sheets, The printing units form a horizontal transport path for the cardboard sheets, Each of the plurality of printing units comprises: a printing cylinder having a printing plate; A press cylinder for pressing a cardboard sheet against the printing cylinder; an anilox roll for transferring ink to the printing plate; Equipped with the plurality of printing units comprises at least one first printing unit and a plurality of second printing units, the number of the at least one first printing unit being equal to or less than the number of the plurality of second printing units; In each first printing unit, the press cylinder is disposed below the printing cylinder, In each second printing unit, the press cylinder is disposed above the printing cylinder; The at least one first printing unit is disposed upstream of the plurality of second printing units in a conveying direction of the cardboard sheet.

[0010] In each second printing unit, the central axis of the anilox roll, which is arranged horizontally along the machine width direction of the corrugated sheet printing press, may be lower than the central axis of the printing cylinder, which is parallel to the central axis of the anilox roll, and may be arranged in a vertical plane including the central axis of the printing cylinder or close to the vertical plane.

[0011] Each second printing unit includes: an ink reservoir mechanism for storing ink to be transferred to the anilox roll; an ink tank for storing ink; an ink supply and recovery mechanism that circulates ink between the ink reservoir mechanism and the ink tank; Equipped with the ink reservoir mechanism is open to the anilox roll side, has an internal space for storing ink, and includes a chamber frame that abuts against the anilox roll; the ink supply and recovery mechanism includes a first ink recovery path that sucks ink from the vicinity of a first end of the internal space and sends it to the ink tank, a second ink recovery path that sucks ink from the vicinity of a second end of the internal space and sends it to the ink tank, and an ink supply path that supplies ink from the ink tank to the internal space midway between the first end and the second end, the first end and the second end being spaced apart in the machine width direction; the first ink recovery path includes a first pump; the second ink recovery path includes a second pump; The first pump and the second pump may be alternately driven to pump ink from the internal space.

[0012] a first liquid level sensor that detects the level of the ink stored in the internal space is provided near a first end of the internal space; a second liquid level sensor is provided near a second end of the internal space to detect the height of the liquid level of the ink stored in the internal space; When either the first liquid level sensor or the second liquid level sensor detects that the level of the ink stored in the internal space has fallen below a predetermined height, the pump that is currently being driven out of the first pump and the second pump is stopped, and thereafter, when both the first liquid level sensor and the second liquid level sensor detect that the level of the ink stored in the internal space has reached the predetermined height, the first pump and the second pump may be driven alternately from the pump that is not the pump that has stopped due to either the first liquid level sensor or the second liquid level sensor detecting that the level of the ink stored in the internal space has fallen below the predetermined height.

[0013] In each second printing unit, the anilox roll is configured to be movable between a first position where ink can be transferred to the printing plate and a second position away from the printing cylinder; A rotary shaft assembly is provided on one end side of the anilox roll, the rotating shaft assembly is fixed to one end of the anilox roll and includes a shaft member that protrudes outward along a central axis of the anilox roll; A gear may be fixed coaxially to the shaft member on the rotating shaft assembly, the gear being connected to a drive mechanism that provides power to rotate the anilox roll.

[0014] Each second printing unit includes a frame assembly that is immobile during lifting and lowering of the anilox roll; the frame assembly is disposed between the anilox roll and the gear and includes a vertical wall having an opening through which the shaft member passes; A first annular seal member may be disposed around the opening between the gear and the vertical wall for sealing between the gear and the vertical wall.

[0015] Each second printing unit includes a movable support assembly that rotatably supports the rotary shaft assembly and moves in accordance with the vertical movement of the anilox roll; A second seal member may be disposed between the movable support assembly and the vertical wall about the periphery of the opening.

[0016] Each second printing unit has a bearing assembly that rotatably supports the rotary shaft assembly, and is provided with a movable support assembly that moves in accordance with the vertical movement of the anilox roll; The movable support assembly may include at least one first oil seal, the at least one first oil seal being disposed around the rotating shaft assembly on the gear side of the bearing assembly.

[0017] Each second printing unit has a bearing assembly that rotatably supports the rotary shaft assembly, and includes a movable support assembly that moves in accordance with the vertical movement of the anilox roll; The movable support assembly may include at least one second oil seal, and the at least two first oil seals may be disposed around the rotating shaft assembly on a side of the bearing assembly facing the anilox roll.

[0018] In the first corrugated sheet printing press, the number of the at least one second printing unit may be one.

[0019] In the first corrugated cardboard sheet printing machine, Each of the plurality of printing units comprises: A feed roll is disposed downstream of the printing cylinder and the press cylinder in the conveying direction of the cardboard sheet; A pair of feed rollers are disposed above the feed roll so as to sandwich the conveyed cardboard sheet; It further comprises: One of the pair of feed rollers is located on one end side of the cardboard sheet being transported, and the other of the pair of feed rollers is located on the other end side of the cardboard sheet being transported, The cylindrical surface of the feed roll is roughened or treated to be rough, In each of the first printing units, the cylindrical surface of the press cylinder may be textured or treated to have an uneven surface.

[0020] The first corrugated board sheet printing machine further comprises: In each second printing unit, A suction mechanism is provided to suck the cardboard sheet S upward. A plurality of guide rollers are provided on the upstream and downstream sides of the press cylinder in combination with the suction mechanism to support the cardboard sheets, The surface of each guide roller is roughened or treated to be rough. The press cylinder and the pair of foot rollers may be configured to support the cardboard sheet in combination with the suction mechanism.

[0021] In the second corrugated sheet printing press, the number of the at least one first printing unit may be one.

[0022] In the second printing machine for corrugated cardboard sheets, Each of the plurality of printing units comprises: A feed roll is disposed downstream of the printing cylinder and the press cylinder in the conveying direction of the cardboard sheet; A pair of feed rollers are disposed above the feed roll so as to sandwich the conveyed cardboard sheet; It further comprises: One of the pair of feed rollers is located on one end side of the cardboard sheet being transported, and the other of the pair of feed rollers is located on the other end side of the cardboard sheet being transported, In each second printing unit, the cylindrical surface of the feed roll and the cylindrical surface of the press cylinder may be textured or treated to have an uneven surface.

[0023] The second printing machine for corrugated cardboard sheets further comprises: Each second printing unit is provided with a suction mechanism that sucks the cardboard sheet upward, A plurality of guide rollers are provided on the upstream and downstream sides of the press cylinder in combination with the suction mechanism to support the cardboard sheets, The cylindrical surface of each guide roller is roughened or treated to be rough. The pair of feed rollers and the press cylinder may be configured to support the cardboard sheet in combination with the suction mechanism.

[0024] According to the first and second printing presses for corrugated board sheets of the present invention, flexographic printing can be performed on both sides of a corrugated board sheet by a continuous series of printing steps. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is an explanatory diagram showing an overview of a printing press for corrugated cardboard sheets according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram showing an overview of a first printing unit provided in the corrugated cardboard sheet printing machine according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is an explanatory diagram showing an overview of a second printing unit provided in the printing machine for corrugated cardboard sheets according to the first embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory diagram showing an overview of a pair of upper and lower feed rolls provided in the second printing unit. [Diagram 5] FIG. 5 is an explanatory diagram showing an outline of an ink supply and recovery mechanism provided in the printing machine for corrugated cardboard sheets according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing the control of the ink supply and recovery mechanism. [Figure 7] FIG. 7 is a cutaway perspective view showing the structure in the vicinity of one end side of the anilox roll of the second printing unit, and also shows a part of the frame assembly of the second printing unit in cutaway form. [Figure 8] FIG. 8 is a cutaway perspective view showing the structure in the vicinity of one end of the anilox roll of the second printing unit. [Figure 9]FIG. 9 is a perspective view showing a part of the frame of the second printing unit in a cutaway. [Figure 10] FIG. 10 is an explanatory diagram showing an overview of a printing press for corrugated cardboard sheets according to a second embodiment of the present invention. [Figure 11] FIG. 11 is an explanatory diagram showing an outline of a printing machine for corrugated cardboard sheets according to a third embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The present invention will be specifically described below with reference to the drawings. Fig. 1 is an explanatory diagram showing an overview of a corrugated board sheet printing machine 1 according to a first embodiment of the present invention. The corrugated board sheet printing machine 1 of the first embodiment performs flexographic printing on a rectangular or approximately rectangular corrugated board sheet S, and more specifically, performs printing in a single color on one side of the corrugated board sheet S and printing in multiple colors (six colors in this embodiment) on the other side of the corrugated board sheet S.

[0027] The printing machine 1 for corrugated board sheets includes a paper feed unit 10 into which a plurality of corrugated board sheets S stacked on a table are loaded, and a plurality of first printing units 20a-f and one second printing unit 40, each of which performs flexographic printing on the corrugated board sheets S. The plurality of first printing units 20a-f and the second printing unit 40 are arranged in a row so as to sequentially perform printing processing on the corrugated board sheets S.

[0028] In this embodiment, the second printing unit 40 is disposed between the series of first printing units 20a-f and the paper feed unit 10. A horizontal transport path for the cardboard sheet S is configured from the paper feed unit 10 to the first printing unit 20f, which is located at a distance, and the cardboard sheet S sent out from the paper feed unit 10 is printed in a single color on its back surface by the second printing unit 40, and then printed in a different color on its top surface by each of the first printing units 20a-f.

[0029] The terms "upstream" and "downstream" used in this specification refer to the relative positions of various components included in the corrugated board sheet printing machine 1 with reference to the horizontal conveying direction P of the corrugated board sheet S. For example, the paper feed unit 10 is said to be disposed upstream of the second printing unit 40.

[0030] The term "machine width direction" used in this specification means a horizontal direction perpendicular to the conveying direction P. The printing press 1 is provided with a pair of rails 3 that are spaced apart in the machine width direction and arranged parallel to each other along the conveying direction P (only one of the rails 3 is shown in FIG. 1). A plurality of wheels 5 guided by these rails 3 are provided on the bottom of the paper feed unit 10, the bottom of the second printing unit 40, and the bottom of each of the first printing units 20a to f, and the paper feed unit 10, each of the first printing units 20a to f, and the second printing unit 40 are configured to be movable along the pair of rails 3. When the printing press 1 is in operation, the paper feed unit 10, the second printing unit 40, and the first printing units 20a to f are connected as shown in FIG. 1. For example, during maintenance of the printing press 1, the units are released from the connection with each other, making it possible to provide a space between the units where an operator can work.

[0031] Downstream of the first printing units 20a-f, which are located on the most downstream side, may be disposed a creaser device, a slotter device, a die cutter device, etc., which process the cardboard sheet S into a form that can be transformed into a cardboard box. Description of these devices will be omitted as they are not related to the present invention.

[0032] The paper feed unit 10 stores a stack of cardboard sheets S to be printed by the printing machine 1, and appropriately supplies the cardboard sheets S from the stack to the downstream printing unit. The cardboard sheet S located at the bottom of the stack of cardboard sheets S loaded in the paper feed unit 10, i.e., the multiple stacked cardboard sheets S, is in frictional contact with multiple feed rollers 11 provided in the paper feed unit 10. By driving these feed rollers 11 to rotate, the cardboard sheet S located at the bottom is pulled out in the conveying direction P. The downstream tip of the pulled-out cardboard sheet S is sandwiched between a pair of upper and lower first feed rolls 13 that are driven to rotate, and further between a pair of upper and lower second feed rolls 15 that are driven to rotate. As a result, the bottom cardboard sheet S from the stack of cardboard sheets S is sent to the second printing unit 40.

[0033] The corrugated board sheet S passes through the second printing unit 40, which performs flexographic printing on the underside of the corrugated board sheet S (details of the second printing unit 40 will be described later), and proceeds to the first printing unit 20a downstream of the second printing unit 40, and further to the first printing unit 20b, the first printing unit 20c, the first printing unit 20d, the first printing unit 20e, and the first printing unit 20f. While proceeding from the paper feed unit 10 to the first printing unit 20f, the corrugated board sheet S maintains a posture in which its longitudinal direction is parallel to the machine width direction. Each of the first printing units 20a to f has a configuration similar to that of a printing unit used in a conventional printing machine, except for a few points. Below, the configuration of the first printing unit 20a will be described as a representative of these first printing units 20a to f.

[0034] 2 is an explanatory diagram showing an overview of the first printing unit 20a. The first printing unit 20a includes a first frame assembly 21 used for arranging various components, a first printing cylinder 23 having a first printing plate 22, a first press cylinder 24 arranged below the first printing cylinder 23 and pressing the corrugated cardboard sheet S toward the first printing cylinder 23, a first anilox roll 25 arranged close to the first printing cylinder 23 and transferring ink to the first printing plate 22, and a first anilox roll 26 arranged near the first printing cylinder 23 and transferring ink to the first printing plate 22. The ink supply and recovery mechanism 27 circulates the ink between the first ink supply and recovery mechanism 26 and the ink tank, a third feed roll 28 disposed downstream of the first printing cylinder 23 and the first press cylinder 24 in the conveying direction P, and a pair of first feed rollers 29 (only one of the first feed rollers 29 is shown in FIG. 2 and other figures) disposed above the third feed roll 28. Each of the first printing cylinder 23, the first press cylinder 24, the first anilox roll 25, and the third feed roll 28 has a cylindrical portion having a rotation center axis along the machine width direction, and a shaft portion protruding from each end of the cylindrical portion in the machine width direction and supported rotatably. The length of these cylindrical portions along the machine end direction is approximately the length of the longitudinal direction of the corrugated cardboard sheet S.

[0035] One of the pair of first feed rollers 29 is located at one end side of the transported cardboard sheet S, and the other of the pair of feed rollers is located at the other end side of the transported cardboard sheet S. Each of the first feed rollers 29 has a central axis of rotation along the machine width direction, and the width of the first feed roller 29 along the machine width direction is significantly shorter than the longitudinal length of the cardboard sheet S, for example, about 10 cm.

[0036] The first printing unit 20a is disposed below the first printing cylinder 23 and further includes a first suction box assembly 30 fluidly connected to a suction device (not shown). The cylindrical portion of the first press cylinder 24 is disposed in the first suction box assembly 30 so as to protrude slightly upward from the upper surface of the first suction box assembly 30. A plurality of first guide rollers 31 spaced apart from each other in the machine width direction are provided on the upstream and downstream sides of the first press cylinder 24, respectively, in the first suction box assembly 30 so as to protrude slightly upward from the upper surface of the first suction box assembly 30 (in the figure, one second guide roller 51 is shown for each of the upstream and downstream sides of the first press cylinder 24). Each first guide roller 31 is configured to rotate passively around a rotation axis along the machine width direction.

[0037] The first press cylinder 24 and the first guide roller 31 are combined with a suction function or mechanism of the first suction box assembly 30, and when a suction device (not shown) sucks the internal space of the first suction box assembly 30, a gap is provided between the member constituting the upper surface of the first suction box assembly 30 and the first press cylinder 24 and the first guide roller 31, so that the cardboard sheet S is sucked downward as it passes through the first printing unit 20a. The number and arrangement of the first guide rollers 31 on the upstream and downstream sides of the first press cylinder 24 may be determined as appropriate.

[0038] As is well known, the ink applied to the first printing plate 22 of the first printing cylinder 23 is transferred to the upper surface of the conveyed cardboard sheet S when the cardboard sheet S passes between the first printing cylinder 23, which is rotated, and the first press cylinder 24, which is also rotated. After passing between the first printing cylinder 23 and the first press cylinder 24, the leading end of the cardboard sheet S is sandwiched between the third feed roll 28, which is rotated, and a pair of first feed rollers 29, which are also rotated, and the cardboard sheet S is advanced further downstream. The first printing cylinder 23, the first press cylinder 24, the third feed roll 28, and the pair of first feed rollers 29 are rotated synchronously with each other by a driving means (not shown). By being sucked downward as described above, misalignment of the cardboard sheet S as it passes through the first printing unit 20a and slippage of the cardboard sheet S against the first press cylinder 24, the third feed roll 28, and the pair of first feed rollers 29 are suppressed, and the transport accuracy of the cardboard sheet S is ensured so that printing misalignment does not occur.

[0039] The first ink reservoir mechanism 26 comprises a bank member 32 arranged opposite the first anilox roll 25, a first doctor blade 33 provided below the bank member 32 and capable of pressing against the first anilox roll 25, and a pair of dam members 34 (only one of the dam members 34 is shown in the figure) arranged in sliding contact with both ends of the first anilox roll 25 and forming an ink reservoir together with the bank member 32.

[0040] The first ink supply and recovery mechanism 27 includes an ink can 35 configured to be movable left and right along the machine width direction, and one or more nozzles 36 for supplying and discharging ink between the ink reservoir of the first ink reservoir mechanism 26 and the ink can 35. An ink supply and recovery pipe (not shown) equipped with a pump is provided between the ink can 35 and an ink tank (not shown) of the first printing unit 20a. The first ink reservoir mechanism 26 and the first ink supply and recovery mechanism 27 may be configured based on or with reference to the ink reservoir mechanism and ink supply and recovery mechanism disclosed in the printing machine described in Japanese Patent Application Laid-Open No. 2006-205614 or Japanese Patent Application Laid-Open No. 2007-118262, for example.

[0041] 3 is an explanatory diagram showing an overview of the second printing unit 40. The second printing unit 40 includes a second frame assembly 41 used for arranging various components, a second printing cylinder 43 having a second printing plate 42, a second press cylinder 44 arranged above the second printing cylinder 43 and pressing the corrugated cardboard sheet S toward the second printing cylinder 43, a second anilox roll 45 arranged close to the second printing cylinder 43 and transferring ink to the second printing plate 42, and a second anilox roll 46 in which the ink transferred to the second anilox roll 45 is stored. The second ink reservoir mechanism 46 includes an ink tank 56 (see FIG. 5) that stores ink, a second ink supply and recovery mechanism 47 (see FIG. 5) that circulates ink between the second ink reservoir mechanism 46 and the ink tank, a fourth feed roll 48 that is disposed downstream of the second printing cylinder 43 and the second press cylinder 44 in the conveying direction P, and a pair of second feed rollers 49 (only one of the second feed rollers 49 is shown in FIGS. 3 and 4, etc.) that are disposed above the fourth feed roll 48. Each of the second printing cylinder 43, the second press cylinder 44, the second anilox roll 45, and the fourth feed roll 48 includes a cylindrical portion having a central axis along the machine width direction, and a shaft portion that protrudes from each end of the cylindrical portion in the machine width direction and is supported rotatably. The length of these cylindrical portions along the machine end direction is approximately the length of the longitudinal direction of the corrugated cardboard sheet S.

[0042] One of the pair of second feed rollers 49 is located on one end side of the transported cardboard sheet S, and the other of the pair of feed rollers is located on the other end side of the transported cardboard sheet S. Each second feed roller 49 has a central axis of rotation along the machine width direction, and the width of the second feed roller 49 along the machine width direction is significantly shorter than the longitudinal length of the cardboard sheet S, for example, about 10 cm.

[0043] The second printing unit 40 is disposed above the second printing cylinder 43, and further includes a second suction box assembly 50 fluidly connected to a suction device (not shown). The cylindrical portion of the second press cylinder 44 and a pair of second feed rollers 49 are disposed in the second suction box assembly 50 so as to protrude slightly downward from the bottom surface of the second suction box assembly 50. On the upstream and downstream sides of the second press cylinder 44, a plurality of second guide rollers 51 are disposed in the second suction box assembly 50 at a distance from each other in the machine end direction, and protrude slightly downward from the bottom surface of the second suction box assembly 50. The second press cylinder 44, the pair of second feed rollers 49, and the second guide roller 51 are combined with a suction function or mechanism of the second suction box assembly 50, and when a suction device (not shown) sucks the internal space of the second suction box assembly 50, a gap is provided between the member constituting the lower surface of the second suction box assembly 50 and the second press cylinder 44, the pair of second feed rollers 49, and the second guide roller 51, so that the cardboard sheet S is sucked downward as it passes through the second printing unit 40. Each second guide roller 51 is configured to rotate passively around a rotation axis along the machine width direction.

[0044] 3 illustrates three second guide rollers 51 on the upstream side of the second press cylinder 44 and one second guide roller 51 on the downstream side, but the second guide rollers 51 may be arranged in a staggered pattern when viewed from above on the upstream side of the second press cylinder 44, and a plurality of second guide rollers 51 spaced apart from each other in the machine end direction are arranged side by side on the downstream side of the second press cylinder 44. The number and arrangement of the second guide rollers 51 on the upstream and downstream sides of the second press cylinder 44 may be determined as appropriate.

[0045] In the second printing unit 40 of this embodiment, the pair of second feed rollers 49, except for their lower ends, are arranged inside the suction box of the second suction box assembly 50, and are combined with a suction function. This allows the cardboard sheet S to be sucked toward the pair of second feed rollers 49 so that the bottom surface of the cardboard sheet S immediately after printing does not come into contact with the fourth feed roll 48 as much as possible.

[0046] In the second printing unit 40, the central axis K of the second anilox roll 45, which is arranged horizontally along the machine width direction of the printing press 1, is lower than the central axis J of the second printing cylinder 43, which is parallel to the central axis K of the second anilox roll 45, and is arranged in a vertical plane V (shown by a dashed line in FIG. 3) including the central axis J of the second printing cylinder 43 or in close proximity to the vertical plane V. For example, the (smaller) angle defined by the vertical plane V and the plane including the central axis K and the central axis J is set to within approximately 20 degrees, more preferably within approximately 10 degrees. In this way, in addition to the second anilox roll 45, the chamber frame 52 and the support member 55, which will be described later, can be arranged together near the lower side of the second printing cylinder 43, and an increase in the length of the second printing unit 40 along the conveying direction P is suppressed.

[0047] The ink applied to the second printing plate 42 of the second printing cylinder 43 is transferred to the underside of the conveyed cardboard sheet S when passing between the second printing cylinder 43 that is rotated and the first press cylinder 24 that is rotated. After passing between the second printing cylinder 43 and the second press cylinder 44, the leading end of the cardboard sheet S is sandwiched between the fourth feed roll 48 that is rotated and the pair of second feed rollers 49 that are rotated, and the cardboard sheet S is further advanced downstream. The second printing cylinder 43, the second press cylinder 44, the fourth feed roll 48, and the pair of second feed rollers 49 are rotated in synchronization with each other by a driving means not shown. By sucking the cardboard sheet S upward so as to pass through the second printing unit 40, the conveying accuracy of the cardboard sheet S is ensured so that printing misalignment does not occur, as in the first printing unit 20a.

[0048] FIG. 4 is an explanatory diagram showing an outline of the fourth feed roll 48 and a pair of second feed rollers 49 provided in the second printing unit 40. The cylindrical portion of each of the upper second feed rollers 49 is covered with urethane resin. The cylindrical portion of the lower fourth feed roll 48 is provided with an uneven surface or uneven surface treatment to suppress ink adhesion from the cardboard sheet S that has been subjected to a reverse printing process by the second printing cylinder 43 (in FIG. 4, the uneven surface or uneven surface treatment is shown by hatching). This reduces the contact area between the fourth feed roll 48 and the cardboard sheet S, and when the fourth feed roll 48 comes into contact with the lower surface of the cardboard sheet S immediately after printing, the amount of ink adhering to the fourth feed roll 48 is reduced.

[0049] For example, the fourth feed roll 48 is made of metal, and the unevenness processing or unevenness treatment may be performed by spraying ceramic on the cylindrical surface of the fourth feed roll 48, by sandblasting, or by knurling, or may be a processing or treatment that increases the surface roughness of the cylindrical surface of the fourth feed roll 48.

[0050] As shown in FIG. 2, the third feed roll 28 of each of the first printing units 20a-f may also have a similar uneven surface treatment or uneven treatment applied to the cylindrical surface that contacts the printed lower surface of the cardboard sheet S. The first press cylinder 24 of each of the first printing units 20a-f (made of metal, for example) may also have a similar uneven surface treatment or uneven surface treatment applied to the cylindrical surface that contacts the lower surface of the cardboard sheet S that is not the printed surface. The first guide roller 31 of each of the first printing units 20a-f may also have a similar uneven surface treatment or uneven surface treatment applied to the first press cylinder 24, the third feed roll 28, and the first guide roller 31 that contacts the lower surface of the cardboard sheet S that is not the printed surface. This prevents ink from adhering to the first press cylinder 24, the third feed roll 28, and the first guide roller 31 from the cardboard sheet S that has been subjected to the reverse printing process in the first printing units 20a-f.

[0051] Referring again to FIG. 3, the second ink reservoir mechanism 46 of the second printing unit 40 includes a chamber frame 52 that opens to the second anilox roll 45 side and has an internal space for storing ink, a second doctor blade 53, and a seal blade 54. The chamber frame 52, the second doctor blade 53, and the seal blade 54 are provided to extend in the machine width direction, and include the second doctor blade 53 and the seal blade 54. The second doctor blade 53 is provided to scrape off excess ink adhering to the surface of the second anilox roll 45. The seal blade 54 functions as a seal to prevent ink leakage from the chamber frame 52. The chamber frame 52 is attached to a support member 55 provided along the machine width direction.

[0052] FIG. 5 is an explanatory diagram showing an outline of the second ink supply and recovery mechanism 47 of the second printing unit 40. The second ink supply and recovery mechanism 47 of the second printing unit 40 includes a first ink recovery path 57 that sucks ink from near the first end of the internal space of the chamber frame 52 and sends it to the ink tank 56, a second ink recovery path 58 that sucks ink from near the second end of the internal space and sends it to the ink tank 56, and an ink supply path 59 that supplies ink from the ink tank 56 to the internal space at a midpoint between the first end and the second end of the internal space. The first end and the second end are separated in the machine width direction. In FIG. 5, the direction in which the ink flows is indicated by an arrow. As is well known, in a printing machine that performs flexographic printing, the ink is kept in an appropriate state by circulating quick-drying ink.

[0053] The first ink recovery path 57 includes a first pump 61 used to suck ink out of the internal space. The second ink recovery path 58 includes a second pump 62 used to suck ink out of the internal space. The first pump 61 and the second pump 62 are, for example, diaphragm pumps. In this embodiment, the first ink recovery path 57 and the second ink recovery path 58 join together and are connected to the ink tank 56 via an ink viscosity sensor 63. A viscosity adjusting means (not shown) is controlled by a controller 67 and adjusts the viscosity of the ink passing through the ink supply path 59 based on the viscosity of the ink measured by the ink viscosity sensor 63.

[0054] The ink supply path 59 is provided with a third pump 64 used to suck ink from the ink tank 56. For example, a tube-type pump is used as the third pump 64. The controller 67 may adjust the rotation speed of the tube-type pump which is the third pump 64 based on the viscosity of the ink measured by the ink viscosity sensor 63.

[0055] 2 is provided at a high position, far away from the floor surface on which the printing machine is installed or its ink tank, as in the conventional printing units, so that it is possible to use gravity to collect ink from the first ink reservoir mechanism 26 and send it to the ink tank. However, in the second printing unit 40, the second printing cylinder 43 is provided below the conveyance path of the corrugated cardboard sheet S, so that the second anilox roll 45 needs to be located near the floor surface, and therefore gravity cannot be used to collect ink from the second ink reservoir mechanism 46 of the second printing unit 40 to the ink tank 56. In this embodiment, by configuring the first pump 61 and the second pump 62 as described above, it is possible to recover ink from the internal space of the chamber frame 52 arranged near the floor surface, and thus it is possible to arrange the second anilox roll 45 near the floor surface. This makes it possible to configure a second printing unit 40 that prints on the back side of the cardboard sheet S and can be used in combination with a series of first printing units 20a-f that print on the front side of the cardboard sheet S.

[0056] A first level sensor 65 for measuring the ink level near the first end is provided in the vicinity of a first end of the internal space of the chamber frame 52. A second level sensor 66 for measuring the ink level near the second end is provided in the vicinity of a second end of the internal space of the chamber frame 52 (terminals of these level sensors 65, 66 are shown in FIG. 5). The first level sensor 65 and the second level sensor 66 (and the viscosity sensor 63) are connected to a controller 67 that controls the operations of the first pump 61, the second pump 62, and the third pump 64. The controller 67 may be composed of a microcomputer.

[0057] During operation of the second printing unit 40, the controller 67 alternately operates the first pump 61 and the second pump 62 to suck ink out of the internal space so as to maintain a constant level of the ink level stored in the internal space of the chamber frame 52 of the second ink reservoir mechanism 46 and to prevent the flow of ink in the internal space from being biased in one direction over time.

[0058] 6 is a flowchart showing the control of the second ink supply and recovery mechanism 47 executed by the controller 67. When the operation of the second printing unit 40 starts, the controller 67 starts the operation of the third pump 64, and the supply of ink from the ink tank 56 to the chamber frame 52 starts (step S1).

[0059] After step S1, the controller 67 judges (step S3) whether or not both the first level sensor 65 and the second level sensor 66 are turned on, that is, whether or not the ink level has reached a predetermined height near both the first end and the second end of the internal space of the chamber frame 52. Step S3 is repeated until both the first level sensor 65 and the second level sensor 66 are turned on.

[0060] When the first and second level sensors 65 and 66 are both turned on, the controller 67 judges whether or not the detection in step S3 that the first and second level sensors 65 and 66 are both on is the first detection (that the sensors 65 and 66 are both on) after the operation of the third pump 64 starts (step S5). If it is judged in step S5 that this is the first detection, the controller 67 operates the first pump 61 and the second pump 62 alternately so as to suck ink from the internal space of the chamber frame 52 from either one of these pumps (step S7).

[0061] After step S7, the controller 67 judges whether or not either the first level sensor 65 or the second level sensor 66 has turned off, that is, whether or not the ink level has fallen below a predetermined height near either the first end or the second end of the internal space of the chamber frame 52 (step S9). Step S9 is repeated until either the first level sensor 65 or the second level sensor 66 turns off, during which the first pump 61 and the second pump 62 alternately operate by switching between them at predetermined intervals (e.g., 3 seconds).

[0062] When it is determined in step S9 that either the first liquid level sensor 65 or the second liquid level sensor 66 has turned off, the controller 67 stops the pump in operation after a predetermined time (e.g., 0.5 seconds) has elapsed since either the first liquid level sensor 65 or the second liquid level sensor 66 turned off (step S11). After step S11, step S3 is executed again.

[0063] If it is determined in step S5 that the detection that both the first liquid level sensor 65 and the second liquid level sensor 66 are on is not the first detection after the operation of the third pump 64 starts, step S11 is executed to determine whether the pump in operation that was stopped is the first pump 61 (step S13). If it is determined in step S13 that the pump stopped in step S11 is the first pump 61, the controller 67 starts the alternating operation of the pumps starting from the second pump 62 after a predetermined time (e.g., 0.5 seconds) has elapsed since both the first liquid level sensor 65 and the second liquid level sensor 66 turned on (step S15). If it is determined in step S13 that the pump stopped in step S11 is not the first pump 61, the controller 67 starts the alternating operation of the pumps starting from the first pump 61 after a predetermined time (e.g., 0.5 seconds) has elapsed since both the first liquid level sensor 65 and the second liquid level sensor 66 turned on (step S17). After step S15 or S17, step S9 is executed.

[0064] The above-mentioned specified intervals, i.e., the continuous operation time of each pump during alternating operation of the first pump 61 and the second pump 62, and the specified times of steps S11, 15 and 17, may be appropriately adjusted so that the state of the ink in the chamber frame 52 is appropriately maintained by the control shown in Figure 6, taking into account the viscosity of the ink used and the start-up time of the first pump 61 and the third pump 64 from a stopped state.

[0065] The second ink reservoir mechanism 46 shown in FIG. 3, the second ink supply and recovery mechanism 47 shown in FIG. 5, and the control of the ink supply and recovery mechanism shown in FIG. 6 are intended to function the second printing unit 40 in which the second ink reservoir mechanism 46 is positioned near the floor surface, but it will be easily understood that they may also be applied to the first printing unit 20a-f as shown in FIG. 2.

[0066] The second anilox roll 45 of the second printing unit 40 is provided so as to be movable up and down for the sake of maintenance, and can be moved between a first position (see FIG. 3) where ink can be transferred to the second printing plate of the second printing cylinder 43, and a second position (not shown) that is spaced downward from the second printing cylinder 43. Axles protrude from each end of the cylindrical part of the second anilox roll 45 in the machine width direction, and the axles are supported by bearing means provided on a plate-like member 71 shown in FIGS. 3 and 6. A drive gear 72 for driving the second anilox roll 45 is fixed to the end of one of the axles (a rotating shaft assembly 82 described later) on the outside of the plate-like member 71. The drive gear 72 is connected to a gear box (not shown) constituting the drive means for the second printing unit 40, and is rotated via the gear box by a main drive motor (not shown) constituting the drive means for the second printing unit 40.

[0067] As shown in Fig. 3, a cylinder type actuator 73 (only one is shown in Fig. 3) is provided above each plate-like member 71, and one end of the cylinder part of the cylinder type actuator 73 is pivotally attached to a bracket fixed to the bottom surface of a cardboard guide member 74 fixed to the second frame assembly 41. One end of the rod part of the cylinder type actuator 73 is pivotally attached to a bracket fixed to the upper corner part on the upstream side of the plate-like member 71. The downstream end of each plate-like member 71 is fixed to the second frame assembly 41 and pivotally attached to a support shaft 75 provided along the machine end direction. Each end of the support member 55 to which the chamber frame 52 is fixed is fixed to the inside of the plate-like member 71 corresponding to that end.

[0068] 3, the second anilox roll 45 is disposed in a position close to the second printing cylinder 43, and from this state, the rod portions of the cylinder-type actuators 73 connected to the plate-like members 71 extend downward, causing the plate-like members 71 to rotate downward around the support shafts 75. As a result, the second anilox roll 45, the support member 55, and the chamber frame 52 connected to the plate-like members 71 also rotate downward around the support shafts 75 so as to move away from the second printing cylinder 43.

[0069] The second printing cylinder 43, the second anilox roll 45, and the second press cylinder 44 of the second printing unit 40 receive driving force from the main drive motor for the second printing unit 40 via a gear box for the second printing unit 40 (both not shown). In the second printing unit 40, the second anilox roll 45 is disposed close to the floor surface, so that it is preferable to immerse the lower end of the drive gear 72 of the second anilox roll 45 in an oil bath (the liquid level L of the oil bath is shown in FIG. 3) and supply lubricating oil to the drive gear 72 or the gear of the gear box meshing therewith by oil bath method in terms of the configuration of the second printing unit 40. However, in this case, it is necessary to prevent the lubricating oil from entering the second anilox roll 45 from the drive gear 72 or the vicinity of the drive gear 72 in the second printing unit 40.

[0070] Fig. 7 is a cutaway perspective view showing the drive gear 72 of the second anilox roll 45 of the second printing unit 40 and the surrounding structure, and also shows a cutaway portion of the second frame assembly 41 of the second printing unit 40. Fig. 8 is a cutaway perspective view showing the structure near one end side of the second anilox roll 45 of the second printing unit 40. Fig. 9 is a cutaway perspective view showing the second frame assembly 41 of the second printing unit 40.

[0071] A rotating shaft assembly 82, which is a shaft portion, is provided at the end of the cylindrical portion of the second anilox roll 45 on the drive gear 72 side. The rotating shaft assembly 82 has a base portion fixed to one end of the second anilox roll 45, and a shaft member 83 protruding outward from the base portion along the central axis of the second anilox roll 45. The rotating shaft assembly 82 further has a cylindrical gear mount 84 inserted into and fixed (for example, by key coupling, etc.) to the shaft member 83. The drive gear 72 is coaxially fixed to the shaft member 83 via the gear mount 84 (for example, by using a bolt, etc.).

[0072] The plate-like member 71 is provided with a bearing assembly 85 having one or more bearings (two in this embodiment) that support the shaft member 83. The plate-like member 71 and the bearing assembly 85 are combined to form a movable support assembly 81.

[0073] On the drive gear 72 side of the second anilox roll 45, the shaft member 83 of the rotary shaft assembly 82 of the second anilox roll 45 is arranged to penetrate a vertical wall portion constituting a part of the second frame assembly 41. The drive gear 72 is arranged outside the wall member 76 constituting the vertical wall portion, and the plate-like member 71 provided with the bearing assembly 85 is arranged inside the wall member 76. In order to enable the lifting and lowering operation of the second anilox roll 45 as described above, the hole 77 of the wall member 76 through which the rotary shaft assembly 82 penetrates and the opening 79 described later are formed sufficiently large so that the parts of the rotary shaft assembly 82 and the movable support assembly 81 that are arranged in the hole 77 or the opening 79 can move in the hole 77 and the opening 79 with the lifting and lowering operation. For this reason, when an oil bath is provided so that the lower end of the drive gear 72 can be immersed, it is necessary to prevent the leakage or movement of lubricating oil to the second anilox roll 45 through the hole 77 and the opening 79 of the wall member 76.

[0074] In consideration of the above requirements, the second printing unit 40 of this embodiment has the following measures to prevent leakage of lubricating oil to the second anilox roll 45. First, the gap between the drive gear 72 and the vertical wall of the second frame assembly 41 is sealed by a seal means disposed therebetween. A first annular seal member 91, specifically a mount member 78 having a groove for fixing a first O-ring, is fixed to the drive gear 72 side of the wall member 76 constituting the vertical wall. The mount member 78 has a diameter larger than the outer diameter of the gear mount 84 and has a circular opening 79 through which the rotary shaft assembly 82 passes. The mount member 78 and the wall member 76 form the vertical wall. The first annular seal member 91 is disposed outside the opening 79.

[0075] The drive gear 72 is provided with an annular plate member 92 that abuts against a first seal member 91 on the second frame assembly 41 side. The radius and position of the O-ring that is the first seal member 91 are determined so that a seal is maintained between the drive gear 72 and the vertical wall portion or the mount member 78 of the second frame assembly 41 at the upper and lower limits of the lifting and lowering operation. The side surface of the drive gear 72 may directly abut against the first seal member 91. The mount member 78 and the wall member 76 may be integrally formed, and the first seal member 91 may be fitted into a groove provided in the drive gear 72 and abut against the vertical wall portion.

[0076] In this embodiment, the outer edge of the annular plate material 92 is configured to protrude radially from the tooth tip or tooth tip circle of the drive gear 72. This prevents the lubricating oil adhering to the teeth of the drive gear 72 from scattering or moving to the vertical wall portion or wall member 76.

[0077] Furthermore, the movable support assembly 81 and the vertical wall or the mount member 78 are also sealed by a sealing means disposed therebetween. The mount member 78 is provided with a groove for fixing a second annular seal member 93, specifically a second O-ring, on the side of the second anilox roll 45. The second annular seal member 93 is disposed outside the opening 79. The movable support assembly 81 has a surface that comes into contact with the second annular seal member 93. The radius and position of the O-ring, which is the second seal member 93, are determined so that a seal is maintained between the movable support assembly 81 and the vertical wall or the mount member 78 of the second frame assembly 41 at the upper and lower limits of the lifting and lowering movement.

[0078] Furthermore, in this embodiment, an annular first oil seal housing 95 is fixed to the drive gear 72 side of the housing of the bearing assembly 85. The first oil seal housing 95 houses a first oil seal 96 provided around the gear mount 84 fixed to the shaft member 83. In this embodiment, the surface that comes into contact with the second seal member 93 in the movable support assembly 81 is provided by an annular plate member 97 fixed to the side surface on the mount member 78 side. Note that a groove in which the second seal member 93 is disposed may be provided in the plate member 97, and the second seal member 93 disposed in the groove may come into contact with the vertical wall portion or the mount member 78.

[0079] Furthermore, in this embodiment, a second oil seal housing 98 having an annular shape is fixed to the bearing housing 86 on the side of the second anilox roll 45. The second oil seal housing 98 houses a second oil seal 99 provided around the shaft member 83. The first oil seal 96 and the second oil seal 99 each have a lip (not shown) that comes into close contact with the gear mount 84, and a spring (shown) for fastening the lip to the gear mount 84, and the like, and prevent the lubricating oil that cannot be prevented from entering even by the first seal member 91 and the second seal member 93 from running down the rotating shaft assembly 82 to reach the cylindrical portion of the second anilox roll 45.

[0080] In this embodiment, the wall member 76 is provided with a lubricating oil passage 94 for recovering, into the oil bath, the lubricating oil that adheres to the inner surface of the wall member 76 that defines the hole 77 and flows downward. A hole that serves as the entrance of the lubricating oil passage 94 is formed in the lowest part of the inner surface of the wall member 76.

[0081] The printing machine 1 of the first embodiment has the above-mentioned configuration, and is capable of double-sided printing of the corrugated board sheet S. Specifically, the second printing unit 40 performs monochromatic printing on the lower surface of the corrugated board sheet S, and the series of first printing units 20a-f downstream of the second printing unit 40 performs multicolor printing on the upper surface of the corrugated board sheet S. Although it is also possible to arrange the series of first printing units 20a-f downstream of the paper feed unit 10 and arrange the second printing unit 40 further downstream to perform multicolor printing on the upper surface of the corrugated board sheet S and then perform monochromatic printing on the lower surface, the printing machine 1 of the first embodiment has the following advantages over a printing machine having such a configuration.

[0082] Generally, when the cardboard sheet S leaves the paper feed unit 10, there is a possibility that the cardboard sheet S may be subjected to a certain degree of impact. This occurs when the cardboard sheet S being conveyed is released from the feed rolls 13, 15 of the paper feed unit 10, and is due to the fact that the cylindrical portions of the feed rolls 13, 15 of the paper feed unit 10 are made of highly elastic rubber in order to pull out the cardboard sheet S from the bottom of the stack of cardboard sheets S.

[0083] When the cardboard sheet S leaves the paper feed unit 10, an impact is generated, which tends to cause a shift in the printing position of the cardboard sheet S in the first printing unit. If a series of first printing units 20a-f are arranged downstream of the paper feed unit 10 and a second printing unit 40 is arranged further downstream, the multi-color printed pattern may become unclear due to the shift in the printing position in the first printing unit. However, in the printing machine of the first embodiment, such a situation is avoided by providing the second printing unit 40, which performs monochrome printing, in the first stage. In other words, in the printing machine 1 of the first embodiment of the present application, even if a slight shift in the position occurs in the monochrome printing pattern applied to the cardboard sheet S in the second printing unit 40, it does not cause a problem in terms of the quality of the cardboard sheet S.

[0084] The number of the second printing units 40 is not limited to one, and a plurality of second printing units 40 each having a different ink color may be provided between the paper feed unit 10 and a series of first printing units 20a-f to perform multi-color printing on the underside of the corrugated cardboard sheet S. FIG. 10 is an explanatory diagram showing an overview of a corrugated cardboard sheet printing machine 1 according to a second embodiment of the present invention. In the second embodiment, six first printing units 20a-f each having a different ink color are provided downstream of two second printing units 40a-b each having a different ink color. Although it is possible to provide two second printing units 40a-b downstream of the six first printing units 20a-f, the printing on the upper surface of the corrugated cardboard sheet S with a larger number of colors may be affected by a print position shift caused by an impact at the paper feed unit 10. Since it is believed that the fewer the number of colors, the less likely printing position misalignment is to be a problem, it is preferable to arrange six first printing units 20a-f downstream of two second printing units 40a-b, as in the printing press 1 of the second embodiment. Furthermore, the number of second printing units and the number of first printing units may be determined arbitrarily, but for these reasons, the number of second printing units is equal to or less than the number of multiple first printing units.

[0085] Also, unlike the printing machine of the first embodiment, after monochromatic printing on the upper surface of the corrugated board sheet S in the first printing unit, multicolor printing may be performed on the lower surface of the corrugated board sheet S in the second and subsequent printing units. FIG. 11 is an explanatory diagram showing an overview of a corrugated board sheet printing machine 1 according to a third embodiment of the present invention, which performs such a printing process. In the third embodiment, six second printing units 40a to 40f are arranged downstream of one first printing unit 20. In the third embodiment, it is not necessary to perform uneven processing or treatment on the surfaces of the first press cylinder 24, the third feed roll 28, and the first guide roller 31 of the first printing unit 20 in order to suppress adhesion of ink, as in the previous embodiment. However, in order to suppress slippage and positional deviation during transport of the corrugated board sheet S, uneven processing or treatment may be performed on the surfaces of the first press cylinder 24, the third feed roll 28, and / or the first guide roller 31.

[0086] In the third embodiment, in addition to the fourth feed roll 48, the second press cylinder 44 and the first guide rollers 31 of each second printing unit 40 may also be textured or processed. This reduces the amount of ink on the upper surface of the cardboard sheet S printed by the printing unit 20 that adheres to the second press cylinder 44 and the first guide rollers 31.

[0087] The number of first printing units 20 is not limited to one, and multiple first printing units 20 each using a different ink color may be provided between the paper feed unit 10 and a series of second printing units 40a-f to perform multi-color printing on the upper surface of the cardboard sheet S. Furthermore, the number of first printing units and the number of second printing units may be arbitrary, but for the reasons described above, the number of first printing units is equal to or less than the number of multiple second printing units.

[0088] In the present invention, it is possible to arrange a second printing unit between two first printing units, or to arrange a first printing unit between two second printing units, but since the suction direction of the first suction box assembly 30 and the suction direction of the second suction box assembly 50 are repeatedly changed relative to the transported cardboard sheet S, it is preferable to arrange the same type of printing units consecutively from the standpoint of the stability of the transport of the cardboard sheet S.

[0089] Thus, in the present invention, at least one second printing unit is disposed between the multiple first printing units and the paper feed unit, and the number of the at least one second printing unit is equal to or less than the number of the multiple first printing units. Alternatively, in the present invention, at least one first printing unit is disposed between the multiple second printing units and the paper feed unit, and the number of the at least one first printing unit is equal to or less than the number of the multiple second printing units.

[0090] The above description is for the purpose of explaining the present invention, and should not be interpreted as limiting the invention described in the claims or narrowing its scope. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims. [Explanation of symbols]

[0091] 1 printing machine 20 First printing unit 20a-f First printing unit 23 First printing cylinder 24 First press cylinder 25 No. 1 Anilox Roll 28 Third Feed Roll 29 First Feed Roller 31 First guide roller 40 Second Printing Unit 40a-d Second printing unit 43 First printing cylinder 44 First press cylinder 45 No. 1 Anilox Roll 46 Second ink reservoir mechanism 47 Second ink supply and recovery mechanism 48 4th Feed Roll 49 Second feed roller 51 Second guide roller 57 First ink recovery route 58 Second ink recovery route 62 First Pump 63 Second Pump 65 First Liquid Level Sensor 66 Second Liquid Level Sensor 72 Drive Gear 76 Wall components 79 Aperture 81 Movable Support Assembly 82 Rotating shaft assembly 83 Shaft member 85 Bearing Assembly 91 First seal member 93 Second sealing member 96 First Oil Seal 99 Second Oil Seal

Claims

1. A printing machine for corrugated cardboard sheets, comprising a plurality of printing units arranged in a row so as to sequentially perform printing processes on the corrugated cardboard sheets, The printing units form a horizontal transport path for the cardboard sheets, Each of the plurality of printing units comprises: a printing cylinder having a printing plate; A press cylinder for pressing a cardboard sheet against the printing cylinder; an anilox roll for transferring ink to the printing plate; Equipped with the plurality of printing units comprises a plurality of first printing units and at least one second printing unit, the number of the at least one second printing unit being less than or equal to the number of the plurality of first printing units; In each first printing unit, the press cylinder is disposed below the printing cylinder, In each second printing unit, the press cylinder is disposed above the printing cylinder; A printing machine for corrugated cardboard sheets, wherein the at least one second printing unit is arranged upstream of the plurality of first printing units in a conveying direction of the corrugated cardboard sheet.

2. A printing machine for corrugated cardboard sheets, comprising a plurality of printing units arranged in a row so as to sequentially perform printing processes on the corrugated cardboard sheets, The printing units form a horizontal transport path for the cardboard sheets, Each of the plurality of printing units comprises: a printing cylinder having a printing plate; A press cylinder for pressing a cardboard sheet against the printing cylinder; an anilox roll for transferring ink to the printing plate; Equipped with the plurality of printing units comprises at least one first printing unit and a plurality of second printing units, the number of the at least one first printing unit being less than or equal to the number of the plurality of second printing units; In each first printing unit, the press cylinder is disposed below the printing cylinder, In each second printing unit, the press cylinder is disposed above the printing cylinder; A printing machine for corrugated cardboard sheets, wherein the at least one first printing unit is arranged upstream of the plurality of second printing units in a conveying direction of the corrugated cardboard sheet.

3. 3. The corrugated board sheet printing press according to claim 1, wherein in each second printing unit, the central axis of the anilox roll, which is arranged horizontally along the machine width direction of the corrugated board sheet printing press, is lower than the central axis of the printing cylinder, which is parallel to the central axis of the anilox roll, and is arranged within or adjacent to a vertical plane including the central axis of the printing cylinder.

4. Each second printing unit includes: an ink reservoir mechanism for storing ink to be transferred to the anilox roll; an ink tank for storing ink; an ink supply and recovery mechanism that circulates ink between the ink reservoir mechanism and the ink tank; Equipped with the ink reservoir mechanism is open to the anilox roll side, has an internal space for storing ink, and includes a chamber frame that abuts against the anilox roll; the ink supply and recovery mechanism includes a first ink recovery path that sucks ink from the vicinity of a first end of the internal space and sends it to the ink tank, a second ink recovery path that sucks ink from the vicinity of a second end of the internal space and sends it to the ink tank, and an ink supply path that supplies ink from the ink tank to the internal space midway between the first end and the second end, the first end and the second end being spaced apart in the machine width direction, the first ink recovery path includes a first pump; the second ink recovery path includes a second pump; 4. The printing machine for corrugated board sheets according to claim 3, wherein the first pump and the second pump are alternately driven to suck ink out of the internal space.

5. a first liquid level sensor is provided near a first end of the internal space to detect the height of the liquid level of the ink stored in the internal space; a second liquid level sensor is provided near a second end of the internal space to detect the height of the liquid level of the ink stored in the internal space; 5. The printing machine for cardboard sheets according to claim 4, wherein when either the first liquid level sensor or the second liquid level sensor detects that the level of the ink stored in the internal space has fallen below a predetermined height, one of the first pump and the second pump that is currently being driven is stopped, and thereafter, when both the first liquid level sensor and the second liquid level sensor detect that the level of the ink stored in the internal space has reached the predetermined height, the first pump and the second pump are alternately driven starting from the pump that is not stopped due to either the first liquid level sensor or the second liquid level sensor detecting that the level of the ink stored in the internal space has fallen below the predetermined height.

6. In each of the second printing units, the anilox roll is configured to be movable between a first position where ink can be transferred to the printing plate and a second position away from the printing cylinder; A rotary shaft assembly is provided on one end side of the anilox roll, the rotating shaft assembly is fixed to one end of the anilox roll and includes a shaft member that protrudes outward along a central axis of the anilox roll; 4. The printing machine for corrugated board sheets according to claim 3, wherein a gear connected to a drive mechanism that provides power to rotate the anilox roll is coaxially fixed to the shaft member of the rotating shaft assembly.

7. Each second printing unit includes a frame assembly that is immovable during lifting and lowering of the anilox roll; the frame assembly is disposed between the anilox roll and the gear and includes a vertical wall having an opening through which the shaft member passes; The printing machine for cardboard sheets according to claim 6, wherein a first annular seal member is disposed around the opening between the gear and the vertical wall portion to seal the gap between the gear and the vertical wall portion.

8. Each second printing unit includes a movable support assembly that rotatably supports the rotary shaft assembly and moves in accordance with the vertical movement of the anilox roll; 8. The printing press for corrugated sheets of claim 7, further comprising a second seal member disposed between the movable support assembly and the vertical wall about the periphery of the opening.

9. Each second printing unit has a bearing assembly for rotatably supporting the rotary shaft assembly, and is provided with a movable support assembly that moves in association with the raising and lowering movement of the anilox roll; 8. The printing machine for corrugated sheets according to claim 7, wherein the movable support assembly includes at least one first oil seal, the at least one first oil seal being disposed around the rotating shaft assembly on the gear side of the bearing assembly.

10. Each second printing unit has a bearing assembly that rotatably supports the rotary shaft assembly, and includes a movable support assembly that moves in accordance with the vertical movement of the anilox roll; 8. The printing press for corrugated board sheets according to claim 7, wherein the movable support assembly includes at least one second oil seal, and the at least two first oil seals are disposed around the rotating shaft assembly on the anilox roll side of the bearing assembly.

11. The printing machine for corrugated board sheets according to claim 1 , wherein the number of said at least one second printing unit is one.

12. Each of the plurality of printing units comprises: A feed roll is disposed downstream of the printing cylinder and the press cylinder in the conveying direction of the cardboard sheet; A pair of feed rollers are disposed above the feed roll so as to sandwich the conveyed cardboard sheet; It further comprises: One of the pair of feed rollers is located on one end side of the cardboard sheet being transported, and the other of the pair of feed rollers is located on the other end side of the cardboard sheet being transported, The cylindrical surface of the feed roll is roughened or treated to be rough, The printing machine for corrugated cardboard sheets according to claim 1 , wherein in each of the first printing units, the cylindrical surface of the press cylinder is subjected to uneven processing or uneven processing.

13. In each second printing unit, A suction mechanism is provided to suck the cardboard sheet S upward, A plurality of guide rollers are provided on the upstream and downstream sides of the press cylinder in combination with the suction mechanism to support the cardboard sheets, The surface of each guide roller is roughened or treated to be rough. The printing machine for corrugated board sheets according to claim 12 , wherein the press cylinder and the pair of feed rollers are configured to support the corrugated board sheet in combination with the suction mechanism.

14. The printing machine for corrugated board sheets according to claim 2 , wherein the number of said at least one first printing unit is one.

15. Each of the plurality of printing units comprises: A feed roll is disposed downstream of the printing cylinder and the press cylinder in the conveying direction of the cardboard sheet; A pair of feed rollers are disposed above the feed roll so as to sandwich the conveyed cardboard sheet; It further comprises: One of the pair of feed rollers is located on one end side of the cardboard sheet being transported, and the other of the pair of feed rollers is located on the other end side of the cardboard sheet being transported, 3. The printing machine for cardboard sheets according to claim 2, wherein in each second printing unit, the cylindrical surface of the feed roll and the cylindrical surface of the press cylinder are subjected to uneven processing or uneven processing.

16. Each second printing unit is provided with a suction mechanism for sucking the cardboard sheet upward, A plurality of guide rollers are provided on the upstream and downstream sides of the press cylinder in combination with the suction mechanism to support the cardboard sheets, The cylindrical surface of each guide roller is roughened or treated to be rough. The printing machine for corrugated board sheets according to claim 15, wherein the pair of feed rollers and the press cylinder are configured to support the corrugated board sheet in combination with the suction mechanism.

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