Printing device

Abstract

A printing device (1) is provided with: a processing cylinder (17) which conveys a sheet (4); a processing device (23) which performs printing on the sheet (4) on the processing cylinder (17); a supply cylinder (16) which supplies the sheet (4) to the processing cylinder (17); a conveyance mechanism (18) which receives the sheet (4) from the processing cylinder (17) and passes the sheet (4) to a device in the next step; and a reversing cylinder (51) which reverses the front and back of the sheet (4) from the conveyance mechanism (18) and supplies the sheet (4) to the supply cylinder (16). According to this configuration, a sheet can be easily reversed at a high speed, and a printing failure can be prevented at the time of the reversal.

Description

printing device

[0001] The present invention relates to a printing apparatus that includes a processing cylinder that holds and transports a sheet, and a processing device that performs processing, including printing, on the sheet on the processing cylinder.

[0002] An example of a conventional printing device equipped with an inkjet head is disclosed in Patent Document 1. The printing device disclosed in Patent Document 1 is equipped with a reversing swing device that turns over a printed sheet and returns it to the printing cylinder, making it possible to print on both sides of the sheet using the inkjet head. The reversing swing device is configured to swing toward the printing cylinder while gripping the trailing edge of the sheet on the upstream side in the sheet conveyance direction, and to hand the sheet over to the printing cylinder gripper device.

[0003] The reversing swing device reverses the sheet through a repetitive motion, so the device itself needs to be accelerated and decelerated. This places a heavy load on the equipment, limiting how fast it can be. Another problem is that when the reversing swing device reverses the sheet, the tail of the sheet (paper end) can become suspended in the air. In other words, the sheet tail (paper end) can swing wildly, causing damage to the sheet, rubbing against surrounding components, and wrinkling, which can lead to printing problems.

[0004] JP 2017-210337 A JP 2013-240987 A JP 5-16330 A

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus that can easily increase the speed of sheet reversal and that does not cause printing problems during reversal.

[0006] One aspect of the present invention is a printing apparatus including a processing cylinder configured to transport a sheet, a processing device configured to perform processing including printing on the sheet on the processing cylinder, a supply cylinder configured to supply the sheet to the processing cylinder, a transport mechanism configured to receive the processed sheet from the processing cylinder and send it to a device for a next process, and a reversing cylinder configured to receive the sheet from the transport mechanism, turn over the sheet, and supply the inverted sheet to the supply cylinder. The reversing cylinder may be in contact with the supply cylinder.

[0007] The reversing drum may include a gripping member configured to grip the rear end of the sheet located upstream in the sheet conveying direction. The gripping member may be configured to rotate relative to the reversing drum about an axis parallel to the axis of the reversing drum. The gripping member may include gripper claws and a gripper base. The gripper claws may be configured to swing between a closed position in which the sheet is clamped between the gripper claws and the gripper base, and an open position in which the gripper claws are separated from the gripper base. The gripping member of the reversing drum may deliver the sheet to the gripping member of the supply drum.

[0008] The conveying mechanism may include a suction drum configured to suction the trailing end of the sheet located upstream in the sheet conveying direction. The reversing drum may include a gripping member configured to grip the trailing end of the sheet suctioned to the suction drum. The gripping member may be configured to rotate relative to the reversing drum about an axis parallel to the axis of the reversing drum. The gripping member may include grippers and a gripping base. The gripping jaws may be configured to swing between a closed position in which the sheet is clamped between the grippers and the gripping base, and an open position in which the grippers are separated from the gripping base. The gripping member of the reversing drum may deliver the sheet to the gripping member of the supply drum.

[0009] The turnover drum may further include a suction member configured to suction the trailing end of the sheet suctioned to the suction drum and deliver the trailing end to the gripping member. The suction member may include a suction surface including suction holes configured to suction the trailing end of the sheet. The trailing end of the sheet is suctioned to the suction surface. The suction member may include a base end supported on the turnover drum so as to be swingable about an axis parallel to the axis of the turnover drum. The suction member can be swung to switch between a state in which the suction surface faces radially outward from the suction drum and a state in which the suction surface faces the gripping member.

[0010] The printing apparatus may further include a delivery unit configured to collect the sheets from the transport mechanism. The transport mechanism may include a sheet path sorting device configured to sort the transport path to either a reversing path including the reversing cylinder or a discharge path that transports the sheets to the delivery unit.

[0011] When the conveying mechanism includes the suction drum, the suction drum may be configured to distribute the conveying path to either an inversion path including the inversion drum or an ejection path that conveys the sheet to the delivery section.

[0012] The printing apparatus may further include a sheet pressure roll that is in contact with the supply cylinder and that rotates while pressing the sheet against the supply cylinder. The reversing cylinder may be configured to supply the inverted sheet to a position on the supply cylinder that is upstream in the sheet conveying direction from a position on the supply cylinder where the sheet is pressed by the sheet pressure roll.

[0013] The printing apparatus may further include a swing device configured to supply the sheet to the supply cylinder. The reversing cylinder may be configured to supply the sheet, with the front and back facing upside down, to a position on the supply cylinder downstream in the sheet conveying direction from a position where the sheet is handed over by the swing device.

[0014] The printing apparatus may further include a heater that heats the outer periphery of the supply cylinder.

[0015] The reversing cylinder, which turns the sheet over, can rotate continuously at a constant rotation speed. The sheet is transported by this reversing cylinder with less swinging of the sheet tail compared to transport using a conventional reversing swing device that accelerates and decelerates. Therefore, according to one aspect of the present invention, a printing device can be provided that can easily increase the sheet reversal speed and does not cause printing problems during reversal.

[0016] FIG. 1 is a side view showing the configuration of a printing apparatus according to a first embodiment. FIG. 2 is a side view showing the main parts of the printing apparatus shown in FIG. 1. FIGS. 3A to 3C are schematic diagrams for explaining the operation of a reversing cylinder. FIG. 4 is a side view showing the configuration of a printing apparatus according to a second embodiment. FIGS. 5A to 5C are schematic diagrams for explaining the operation of a reversing cylinder.

[0017] First Embodiment A printing apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3A to 3C.

[0018] The conveying device 1 conveys sheets 4 from a feeder section 2 located at the rightmost position in Fig. 1 to a printing unit 3, where printing is performed on one or both sides of the sheets 4. The sheets 4 printed in the printing unit 3 are sent to a delivery section 5 and accumulated in a delivery pile 6.

[0019] The feeder section 2 has a structure in which sheets 4 are transferred from a feeder pile 11 to a feeder board 13 by suckers 12. The suckers 12 are connected to an intermittent paper feed valve 14 and operate in either a mode in which the sheets 4 are continuously fed or a mode in which the sheets 4 are intermittently fed. When printing is to be performed only on the front side of the sheet 4, the suckers 12 continuously feed the sheet 4 to the feeder board 13. On the other hand, when printing is to be performed on both the front and back sides of the sheet 4, the suckers 12 intermittently feed the sheet 4 to the feeder board 13.

[0020] The printing unit 3 includes a supply cylinder 16 to which the sheet 4 from the feeder section 2 is supplied by a swing device 15, a processing cylinder 17 to which the sheet 4 is fed from the supply cylinder 16, and a conveying mechanism 18 to which the sheet 4 is fed after printing.

[0021] The supply drum 16 is a double-sized drum with a diameter twice that of a single drum, and has two conveying surfaces 16a in the rotational direction, as shown in FIG. 2, on which the sheet 4 is held. These two conveying surfaces 16a are formed on the outer peripheral surface of the supply drum 16, and bisect the outer peripheral surface in the rotational direction as viewed axially of the supply drum 16. A peripheral notch 16b is provided between adjacent conveying surfaces 16a. A gripper device 44 is provided within the peripheral notch 16b. The gripper device 44 grips and holds the leading end 4a of the sheet 4, which is the end on the downstream side in the sheet conveying direction, and supplies the sheet 4 received from the swing device 15 to the processing drum 17 at the supply position P1.

[0022] A heater 21 is disposed near the supply cylinder 16 to heat the outer periphery of the supply cylinder 16. By heating the supply cylinder 16 with the heater 21, the heat of the supply cylinder 16 is transferred to the sheet 4 while the sheet 4 is being transported by the supply cylinder 16, causing the temperature of the sheet 4 to rise.

[0023] A sheet pressure roll 22 is in contact with the outer peripheral surface of the supply drum 16 between the supply position P1 and the position P4 where the sheet 4 is supplied by the swing device 15. The sheet pressure roll 22 rotates while pressing the sheet 4 being conveyed by the supply drum 16 against the supply drum 16. By pressing the sheet 4 against the supply drum 16 in this way by the sheet pressure roll 22, the heat of the supply drum 16 is efficiently transferred to the sheet 4, and the temperature of the sheet 4 can be reliably raised to the target temperature.

[0024] The processing drum 17 attracts the sheet 4 and transports it to a position where it is processed by a processing device 23, which will be described later. The processing drum 17 in this embodiment is a triple-diameter drum having a diameter three times that of a single drum, and has three conveying surfaces 17a that hold the sheet 4 in the rotational direction, as shown in FIG. 2 . These three conveying surfaces 17a are formed on the outer peripheral surface of the processing drum 17, and divide the outer peripheral surface into three equal parts in the rotational direction as viewed from the axial direction of the processing drum 17. Peripheral cutouts 24 are provided between adjacent conveying surfaces 17a. Gripper devices 25 are provided within the peripheral cutouts 24. The gripper devices 25 grip and hold the leading end 4a of the sheet 4, which is the end on the downstream side in the sheet transport direction.

[0025] Downstream of the supply cylinder 16 in the sheet transport direction, a preprinting treatment device 31, first, second, third, and fourth inkjet heads 26, 27, 28, and 29, and an ink drying lamp 30 are arranged in this order in the sheet transport direction near the periphery of the treatment cylinder 17. The preprinting treatment device 31 is, for example, a precoat device that applies a precoat to the sheet 4 before printing, or a corona treatment device that applies a corona discharge treatment to the sheet 4 before printing.

[0026] The first to fourth inkjet heads 26 to 29 perform printing by ejecting ink droplets onto the sheet 4. Although not shown, each of these first to fourth inkjet heads 26 to 29 has a plurality of nozzles arranged in the axial direction of the processing cylinder 17 (a direction perpendicular to the paper surface of FIG. 2 ). Each of the first to fourth inkjet heads 26 to 29 also has a heater (not shown) that heats the ink to a predetermined temperature so that the ink droplets will adhere properly to the sheet 4.

[0027] The ink drying lamp 30 is used to harden the ink applied to the sheet 4 by the first to fourth inkjet heads 26 to 29. The ink drying lamp 30 irradiates the sheet 4 with infrared or ultraviolet light. The ink dries or hardens when irradiated with infrared or ultraviolet light.

[0028] In this embodiment, the pre-printing treatment device 31, the first to fourth inkjet heads 26 to 29, and the ink drying lamp 30 constitute the treatment device 23 that performs treatments, including printing, on the sheet 4 on the treatment cylinder 17. Note that the pre-printing treatment device 31 and the ink drying lamp 30 are not essential.

[0029] The transport mechanism 18 is configured using multiple transport cylinders, and receives the printed sheet 4 at a receiving position P2 located downstream in the sheet transport direction from the first to fourth inkjet heads 26 to 29. The multiple transport cylinders are a discharge cylinder 41 that receives the sheet 4 from the processing cylinder 17 at the receiving position P2, a discharge-side transfer cylinder 42 that receives the sheet 4 from the discharge cylinder 41, and a pre-reversal double cylinder 43 that receives the sheet 4 from the discharge-side transfer cylinder 42.

[0030] The above-mentioned supply cylinder 16, discharge cylinder 41, discharge-side transfer cylinder 42, and pre-reversal double cylinder 43 are each provided with gripper devices 44, 45, 46, and 47 to transfer the sheet 4. These gripper devices 44 to 47 are equivalent to the gripper device 25 of the processing cylinder 17.

[0031] Of the sheets 4 received by the discharge drum 41 at the receiving position P2, those that are to be printed on the back side as well are returned upside down to the supply drum 16 via a reversal path 52 consisting of a discharge-side transfer drum 42, a pre-reversal double cylinder 43, and a reversal drum 51 (described later). On the other hand, those that are to be printed on only the front side or those that are printed on both the front and back sides are discharged from the discharge drum 41 via a discharge path 54 including a delivery belt 53 to the delivery section 5.

[0032] In this embodiment, the discharge drum 41 constitutes a sheet path sorting device that sorts the conveying path to either a reversal path 52 where the sheet 4 is reversed, or a discharge path 54 where the sheet 4 is discharged. This sheet path sorting device can be constructed using, for example, the technology disclosed in Patent Document 2. Patent Document 2 discloses a cam device that uses a cam that opens and closes the gripper device 45 of the discharge drum 41 to change the opening and closing timing of the gripper device 45 (the timing of delivery of the sheet 4). The cam device is configured so that the sheet 4 is delivered from the discharge drum 41 to either the gripper device 46 of the discharge-side transfer drum 42 or a gripper device (not shown) that moves together with the delivery belt 53.

[0033] The delivery unit 5 has three functions. The first function is to accumulate printed sheets 4 from the transport mechanism 18 in a delivery pile 6. The second function is to extract samples. The third function is to transport the sheets 4 to the next process.

[0034] Reversing cylinder 51 rotates in synchronization with cylinders 41 to 43 constituting conveying mechanism 18, receives sheet 4 from conveying mechanism 18, turns over sheet 4, and supplies the turned-over sheet 4 to supply cylinder 16. Reversing cylinder 51 in this embodiment is equivalent to the turning drum disclosed in Patent Document 3, for example, and has a gripping member 55 that grips the rear end 4b of sheet 4 located upstream in the sheet conveying direction being conveyed by pre-reversing double cylinder 43, as shown in Figures 3A to 3C. Grip member 55 is rotatable relative to reversing cylinder 51 around an axis parallel to the axis of reversing cylinder 51.

[0035] The reversal of the sheet 4 will be described with reference to Figures 3A to 3C. The sheet 4 is transported by the pre-reversal doubler cylinder 43 with the printed surface 4c in contact with the pre-reversal doubler cylinder 43. As shown in Figure 3A, when the trailing end 4b of the sheet 4 passes between the pre-reversal doubler cylinder 43 and the reversal cylinder 51, the gripping member 55 of the reversal cylinder 51 grips and holds the trailing end 4b of the sheet 4. As the reversal cylinder 51 rotates in this state, the sheet 4 is transported toward the supply cylinder 16 with the trailing end 4b of the sheet 4 positioned downstream in the sheet transport direction, as shown in Figures 3B and 3C. The sheet 4 transported through the reversal path 52 in this manner is delivered to the supply cylinder 16 at the delivery position P3 shown in Figures 1 and 2. As the sheet 4 is transported by the supply cylinder 16, the surface 4c of the sheet 4 is exposed outside the supply cylinder 16. Therefore, the sheet 4 transported through the reversal path 52 is transported from the supply cylinder 16 to the processing cylinder 17 in an inverted state.

[0036] The delivery position P3 is downstream in the sheet conveying direction of the receiving position P4 where the supply cylinder 16 receives the sheet 4 from the swing device 15, and is upstream in the sheet conveying direction of the pressing position P5 where the sheet 4 is pressed by the sheet pressure roll 22. In other words, the reversing cylinder 51 is configured to supply the inverted sheet 4 to a position on the supply cylinder 16 downstream of the receiving position P4 and upstream of the pressing position P5. Therefore, the inverted sheet 4 is also pressed down by the sheet pressure roll 22 and then delivered to the processing cylinder 17.

[0037] As described above, the reversing cylinder 51, which turns the sheet 4 over, can rotate continuously at a constant rotation speed. When the reversing cylinder 51 transports the sheet 4, the tail end of the sheet 4 is less likely to shake compared to when a conventional reversing swing device accelerates and decelerates the transport. Therefore, according to this embodiment, it is possible to provide a printing device that can easily increase the speed of the sheet 4 and does not cause printing problems during reversing.

[0038] In this embodiment, the reversing cylinder 51 has a gripping member 55 that grips the rear end 4b of the sheet 4 located upstream in the sheet conveying direction. The gripping member 55 is configured to rotate relative to the reversing cylinder 51 about an axis parallel to the axis of the reversing cylinder 51. Therefore, the sheet 4 conveyed by the reversing cylinder 51 follows the outer peripheral surface of the reversing cylinder 51, which makes it easier to stabilize the posture of the sheet 4 during conveyance.

[0039] Second Embodiment Next, a printing device according to a second embodiment of the present invention will be described with reference to Figure 4 and Figures 5A to 5C. In these figures, elements that are the same as or equivalent to those shown in Figures 1 to 3C are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0040] The printing apparatus 61 shown in FIG. 4 differs from the printing apparatus 1 shown in FIG. 1 in that the supply cylinder 16 is composed of a single cylinder, the transport mechanism 18 that receives the sheet 4 from the processing cylinder 17 is composed of a single suction cylinder 62, and a reversing cylinder 63 of the suction reversal type is used, but the other configurations are the same as those of the printing apparatus 1 shown in FIG. 1.

[0041] The suction cylinder 62 conveys the sheet 4 while holding the leading end 4a, which is the end of the sheet 4 on the downstream side in the sheet conveying direction, and adsorbing the trailing end 4b, which is the end of the sheet 4 on the upstream side. The suction cylinder 62 is a double-sized cylinder and has conveying surfaces 62a on which the sheet 4 is held at two locations in the rotational direction. These two conveying surfaces 62a are formed by the outer peripheral surface of the suction cylinder 62 and divide the outer peripheral surface into two equal parts in the rotational direction when viewed from the axial direction of the suction cylinder 62. An outer peripheral cutout 62b is provided between adjacent conveying surfaces 62a.

[0042] A gripper device 64 is provided upstream in the outer peripheral cutout 62b in the sheet conveying direction. The gripper device 64 is equivalent to the gripper device 25 of the processing cylinder 17, and grips and holds the leading end 4a of the sheet 4. A suction device 65 is provided downstream in the outer peripheral cutout 62b in the sheet conveying direction. The suction device 65 sucks the trailing end 4b of the sheet 4 by applying negative pressure from a negative pressure source, and brings the trailing end portion of the sheet 4 into close contact with the outer peripheral surface of the suction cylinder 62.

[0043] The reversing cylinder 63 receives the sheet 4 from the suction cylinder 62, turns the sheet 4 over, and sends it to the supply cylinder 16. The reversing cylinder 63 is a single cylinder, and as shown in Figure 5, has a notch 66 that opens to its outer circumferential surface. An attraction member 67 is provided downstream in the notch 66 in the sheet conveyance direction, and a gripper device 68 (grip member) that grips the sheet 4 is provided upstream in the notch 66 in the sheet conveyance direction.

[0044] The tip of the suction member 67 includes a suction surface 67a with a number of suction holes that suck the sheet 4, and the sheet 4 is attracted to this suction surface 67a. A base end 67b of the suction member 67 is supported by the reversing drum 63 so as to be able to swing freely around an axis parallel to the axis of the reversing drum 63. By swinging the suction member 67, the suction member 67 can be placed in a state in which the suction surface 67a faces radially outward from the suction drum 62 (FIG. 5A), or in a state in which the suction surface 67a faces toward the gripper device 68 (upstream) (FIG. 5B).

[0045] The gripper device 68 has grippers 68a and gripper bases 68b. The grippers 68a are supported so as to be able to swing between a closed position in which the grippers 68a and gripper bases 68b clamp the sheet 4, and an open position in which the grippers 68a are spaced apart from the gripper bases 68b. The gripper device 68 is supported on the reversing drum 63 so as to be able to swing about an axis parallel to the axis of the reversing drum 63. By swinging the gripper device 68, the gripper device 68 can be placed in a state in which the tip portions of the grippers 68a and gripper bases 68b face toward the suction member 67 (downstream) ( FIG. 5B ), or in a state in which the tip portions of the grippers 68a and gripper bases 68b face radially outward from the suction drum 62 ( FIG. 5C ).

[0046] In this embodiment, the printed sheet 4 is sent from the processing cylinder 17 to the suction cylinder 62. Of the sheets 4 received by the suction cylinder 62, those that are to be printed on the back side also travel through a reversing path 71 from the suction cylinder 62 to the reversing cylinder 63 and are returned to the supply cylinder 16 in an inverted state. On the other hand, sheets 4 that are to be printed on only the front side 4c or sheets 4 that are printed on both the front and back sides are discharged from the suction cylinder 62 to the delivery section 5 through a discharge path 73 including a delivery belt 72 (see FIG. 4). In this embodiment, the suction cylinder 62 constitutes a sheet path sorting device that sorts the conveyance path to either the reversing path 71, where the sheet 4 is reversed, or the discharge path 73, where the sheet 4 is discharged.

[0047] The sheet 4 transferred from the processing cylinder 17 to the suction cylinder 62 is conveyed by the suction cylinder 62 with its leading end 4a held by the gripper device 64 and its trailing end 4b being attracted to the suction device 65. To turn the sheet 4 over, first, as shown in Figure 5A, the trailing end 4b of the sheet 4 being conveyed by the suction cylinder 62 is attracted to the suction member 67 of the reversing cylinder 63.

[0048] More specifically, when the trailing end 4b of the sheet 4 is about to pass between the suction cylinder 62 and the reversing cylinder 63, the suction member 67 of the reversing cylinder 63, whose suction surface 67a faces radially outward from the suction cylinder 62, begins suction, the suction device 65 of the suction cylinder 62 stops suctioning the trailing end 4b of the sheet 4, and the gripper device 64 of the suction cylinder 62 releases the leading end 4a of the sheet 4. As a result, the trailing end 4b of the sheet 4 is transferred from the suction device 65 of the suction cylinder 62 to the suction member 67 of the reversing cylinder 63.

[0049] Next, the suction member 67, with the trailing end 4b of the sheet 4 attracted to its suction surface 67a, and the gripper device 68, with its tip facing radially outward from the suction cylinder 62, both rotate toward the inside of the notch 66 (in the direction of the arrow in FIG. 5A ), so that the suction surface 67a of the suction member 67 faces the tips of the gripper 68a and the gripper base 68b, as shown in FIG. 5B . At this time, the gripper 68a approaches the gripper base 68b, causing the gripper 68a and the gripper base 68b to grip and hold the trailing end 4b of the sheet 4. At the same time, the suction member 67 stops suctioning the trailing end 4b of the sheet 4, and the trailing end 4b of the sheet 4 is transferred from the suction member 67 to the gripper device 68.

[0050] The grippers 68a and gripper bases 68b that hold the rear end 4b of the sheet 4 rotate toward the outside of the notch 66 (the opposite direction to the direction of the arrow shown in FIG. 5A ) in accordance with the rotation of the reversing drum 63. This causes the sheet 4 to extend along the outer circumferential surface of the reversing drum 63.

[0051] 5C , when the trailing end 4b of the sheet 4 is about to pass between the reversing cylinder 63 and the supply cylinder 16, the tip end of the gripper device 68 of the reversing cylinder 63 faces radially outward from the reversing cylinder 63 and faces the gripper device 44 of the supply cylinder 16. The gripper 68a moves away from the gripper base 68b, and the trailing end 4b of the sheet 4 is transferred from the gripper device 68 of the reversing cylinder 63 to the gripper device 44 of the supply cylinder 16.

[0052] When this sheet 4 is transported by the supply cylinder 16, the front surface 4c of the sheet 4 is exposed to the outside of the supply cylinder 16. Therefore, the sheet 4 transported through the reversing path 71 is transported from the supply cylinder 16 to the processing cylinder 17 in an inverted state.

[0053] The reversing cylinder 63 can be rotated continuously at a constant rotation speed. Therefore, in this embodiment as well, it is possible to provide a printing device that can easily increase the speed of reversing the sheet 4 and that does not cause printing problems during reversing.

[0054] In this embodiment, the conveying mechanism 18 is configured with a suction cylinder 62 that suctions the trailing end 4b of the sheet 4. The reversing cylinder 63 has a gripper device 68 (grip member) that grips the trailing end 4b of the sheet 4 that has been sucked onto the suction cylinder 62. The gripper device 68 is configured to rotate relative to the reversing cylinder 63 about an axis that is parallel to the axis of the reversing cylinder 63. Therefore, the sheet 4 conveyed by the reversing cylinder 63 follows the outer peripheral surface of the reversing cylinder 63, which makes it easier to stabilize the posture of the sheet 4 during conveyance.

[0055] The conveying mechanism 18 shown in the first and second embodiments has a sheet path sorting device that sorts the conveying path to either a reversing path 71 including a reversing drum 63 or a discharge path 73 that transports the sheet 4 to the delivery unit 5 where the sheet 4 is accumulated. This makes it easy to switch between an operating mode in which printing is performed on only one side of the sheet 4 and an operating mode in which printing is performed on both sides of the sheet 4. Note that, in the second embodiment, as in the first embodiment, a discharge drum 41 and a discharge-side transfer drum 42 that function as a sheet path sorting device may be provided in addition to the suction drum 62.

[0056] The supply cylinder 16 shown in the first and second embodiments is in contact with a sheet pressure roll 22 that rotates while pressing the sheet 4 against the supply cylinder 16. Therefore, the heat of the supply cylinder 16 that the sheet 4 contacts can be used to raise the temperature of the sheet 4 supplied to the processing cylinder 17 to a predetermined temperature, making it less likely that the temperature of the sheet 4 will be uneven.

[0057] 1, 61...printing device, 4...sheet, 5...delivery section, 16...supply cylinder, 17...processing cylinder, 18...conveying mechanism, 22...sheet pressure roll, 23...processing device, 41...discharge cylinder (sheet path sorting device), 51, 63...reversing cylinder, 52, 71...reversing path, 54, 73...discharge path, 55...gripping member, 62...suction cylinder (sheet path sorting device), 67...suction member (gripping member), 68...reversing cylinder gripper device (gripping member).

Claims

1. A printing apparatus comprising: a processing cylinder configured to convey a sheet; a processing device configured to perform a process including printing on the sheet on the processing cylinder; a supply cylinder configured to supply the sheet to the processing cylinder; a transport mechanism configured to receive the processed sheet from the processing cylinder and send it to a device in the next step; and a reversing cylinder configured to receive the sheet from the transport mechanism, reverse the front and back of the sheet, and supply the sheet with the reversed front and back to the supply cylinder.

2. The printing apparatus according to claim 1, wherein the reversing cylinder includes a grip member configured to hold the rear end of the sheet located on the upstream side in the sheet transport direction, and the grip member is configured to pivot with respect to the reversing cylinder about an axis parallel to the axis of the reversing cylinder.

3. The printing apparatus according to claim 1, wherein the transport mechanism includes a suction cylinder configured to suck the rear end of the sheet located on the upstream side in the sheet transport direction, the reversing cylinder includes a grip member configured to hold the rear end of the sheet sucked by the suction cylinder, and the grip member is configured to pivot with respect to the reversing cylinder about an axis parallel to the axis of the reversing cylinder.

4. The printing apparatus according to claim 2 or 3, further comprising a delivery unit configured to accumulate the sheets from the transport mechanism, wherein the transport mechanism includes a sheet path distribution device configured to distribute the transport path to either a reversing path including the reversing cylinder or a discharge path for transporting the sheet to the delivery unit.

5. The printing apparatus according to claim 3, further comprising a delivery unit configured to accumulate the sheets from the transport mechanism, wherein the suction cylinder is configured to distribute the transport path to either a reversing path including the reversing cylinder or a discharge path for transporting the sheet to the delivery unit.

6. The printing apparatus according to claim 1, further comprising a sheet pressing roll configured to be in contact with the supply cylinder and rotate while pressing the sheet against the supply cylinder, wherein the reversing cylinder is configured to supply the sheet with its front and back sides reversed at a position upstream of the position where the sheet is pressed by the sheet pressing roll on the supply cylinder in the sheet conveyance direction.

7. The printing apparatus according to claim 1 or 6, further comprising a swing device configured to supply the sheet to the supply cylinder, wherein the reversing cylinder is configured to supply the sheet with its front and back sides reversed at a position downstream of the position where the sheet is transferred by the swing device on the supply cylinder in the sheet conveyance direction.

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