Sheet-fed printing press

Abstract

To provide a sheet-fed printing press capable of surely discharging a final sheet before switching to a downstream side discharged sheet holding part to an upstream side discharged sheet holding part regardless of the size of the sheet in the vertical direction.SOLUTION: This device has a plurality of paper delivery holding parts for respectively holding a paper delivery pile for stacking paper sheets, a paper delivery gripper 44 for carrying the paper sheet to the paper delivery holding part, and a paper abutment 45 for abutting on the paper head of the carried paper sheet. An image forming apparatus includes: a sheet discharge device which can switch a sheet discharge holding unit which is a sheet discharge target; a paper guide (48) which guides a sheet of paper in an upstream side sheet discharge holding unit; and an air blowing unit (49) which blows air to the sheet of paper conveyed above the upstream side sheet discharge holding unit, wherein the air blowing unit (49) is located downstream of an upstream end of a sheet discharge pile held by the upstream side sheet discharge holding unit and upstream of a paper stop (45) provided in the sheet discharge holding unit. It is arranged above the moving locus of the delivery gripper 44 and the advancing / retreating locus of the paper guide 48, and the direction of air injection is toward the upstream side end of the delivery pile.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sheet-fed printing press equipped with a paper delivery section. [Background technology]

[0002] Patent document 1 discloses a sheet-fed printing press that has two deliveries (a first delivery and a second delivery) that each hold an output pile of multiple sheets, and that can change the output position of sheets transported by an output gripper so that they can be output to either the first delivery on the upstream side or the second delivery on the downstream side.

[0003] In the above-mentioned sheet-fed printing press, in order to prevent malfunctions caused by the configuration that allows the sheet discharge position to be switched, the press is equipped with a vacuum car side guide member on the trailing edge side and a paper pressing side guide member on the leading edge side, which are paper guides that move in and out over the stacked sheets (first discharge pile) of the first delivery, and a blowing member that blows air from directly above the top surface of the sheets discharged from above the horizontal conveying track of the discharge gripper onto the top surface of the sheets discharged to the first discharge pile of the first delivery.

[0004] When discharging sheets to the second discharge pile of the second delivery, the paper guide advances above the first discharge pile to support and guide the underside of the tail end of the sheet so that the tail end of the sheet passing over the first discharge pile and heading to the second discharge pile does not droop excessively. This prevents problems such as scratches caused by the tail end of the sheet heading to the second discharge pile coming into contact with the top surface (printed surface) of the top sheet in the first discharge pile.

[0005] The blowing members include an upstream upper air blowing member and a downstream upper air blowing member. When switching the sheet discharge position from the first delivery to the second delivery during printing, the upstream upper air blowing member sprays air toward the upper surface (upper surface at the upstream end) of the tail end of the first discharge pile for a short period of time while the tail end of the last sheet discharged to the first delivery is moving downward as it exits the first vacuum suction section. In other words, air is blown toward the tail end of the last sheet that has exited the first vacuum suction section. This causes the tail end to fall quickly, preventing the tail end of the last sheet from colliding with the vacuum car-side guide member on the tail end side that advances onto the first discharge pile to support and guide subsequent sheets heading for the second discharge pile. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2009 / 044688 Summary of the Invention [Problem to be solved by the invention]

[0007] The period during which the upstream upper air blowing member can blow air onto the trailing edge of the final sheet (blowing period) is the time from when the trailing edge of the final sheet discharged to the first delivery exits the first vacuum suction section to when the discharge gripper, which holds and transports the first sheet to be discharged to the next second delivery, reaches directly below the upstream upper air blowing member (when it blocks the air being blown out from the upstream upper air blowing member).

[0008] As a result, for thin sheets (sheets of paper in the present application) with large vertical dimensions, the timing at which the tail end of the final sheet discharged to the first delivery leaves the first vacuum suction section is extremely delayed. Therefore, the discharge gripper reaches directly below the upstream upper air blowing member by the time the sheet leaves. The air blown from the upstream upper air blowing member is blocked by the discharge gripper, eliminating or shortening the period during which the upstream upper air blowing member can blow air. Furthermore, because the upstream upper air blowing member is configured to blow air directly downward, the range of air blown onto the sheet's tail end is limited in the vertical direction. This can result in poor delivery of the final sheet (sheets of paper in the present application) to the first delivery (upstream discharge holding section in the present application), leaving room for improvement.

[0009] The present invention has been made to solve such problems, and aims to provide a sheet-fed printing press that, when switching the paper discharge position from the upstream paper discharge holding section to the downstream paper discharge holding section, can reliably discharge the last sheet before switching to the upstream paper discharge holding section, regardless of the size of the sheet in the vertical direction. [Means for solving the problem]

[0010] In order to achieve the above object, a sheet-fed printing press according to the present invention comprises a plurality of output paper holding sections, each holding an output pile of a plurality of sheets, an output paper gripper that transports the sheets to the output paper holding sections, a paper stopper against which the head of the transported sheet comes into contact, and which is capable of switching the output paper holding section to which the sheet is to be discharged, a paper guide that guides the sheet in the output paper holding section that is relatively upstream in the transport direction among the plurality of output paper holding sections, and an air blowing section that blows air toward the sheet being transported above the output paper holding section that is relatively upstream in the transport direction among the plurality of output paper holding sections, and the output paper gripper circulates above the plurality of output paper holding sections from the upstream side to the downstream side in the transport direction, and can transport the sheet downstream by gripping the head of the sheet, and the sheet being transported can be moved by the output paper gripper against the output paper gripper. The paper holder is located downstream of each of the multiple paper discharge holding sections and guides the sheets released from the paper discharge gripper onto the paper discharge pile held by each of the paper discharge holding sections. The paper guide is configured to be able to move back and forth along the conveying direction and guides the sheets to the paper discharge holding section which is relatively downstream while preventing the sheets from descending into the paper discharge holding section which is relatively upstream. The air ejection section is located downstream of the upstream end of the paper discharge pile held by the paper discharge holding section which is relatively upstream and upstream of the paper holder provided on the paper discharge holding section, and is positioned above the movement trajectory of the paper discharge gripper and the advance and retreat trajectory of the paper guide, and the direction of the air ejection is toward the top surface of the upstream end of the paper discharge pile.

[0011] According to the above configuration, the direction of air blown by the air blowing unit toward the upper surface of the upstream end of the discharged paper pile is downward and inclined toward the upstream side, which delays the timing at which the discharged paper gripper blocks the air blown from the air blowing unit. This allows for a longer blowing period. Moreover, the range of air blown toward the upper surface of the upstream end of the discharged paper pile is expanded, making it possible to accommodate sheets of various sizes. Furthermore, because the air blowing unit is located upstream of the paper holder, a decrease in the flow rate of the air blown toward the upper surface of the upstream end of the discharged paper pile can be suppressed.

[0012] In addition, the sheet-fed printing press of the present invention may have a paper guide that has an upstream guide section located upstream of each of the multiple discharge paper holding sections and a downstream guide section located downstream, and the air ejection section may be positioned at a position that coincides with the upstream guide section in the width direction of the sheet transported by the discharge paper gripper.

[0013] As described above, the airflow blown by the air ejection section can quickly lower the last sheet of paper before the discharged paper holding section is switched, thereby preventing the sheet of paper from getting caught in the upstream guide section during the advancing operation.

[0014] Furthermore, in the sheet-fed printing press according to the present invention, the paper guide may be configured such that the vertical dimension on the advancing direction side is smaller than that on the retreating direction side.

[0015] As described above, the side of the paper guide in the direction of advancement is thin, so that it is even less likely to get caught on the paper sheets. [Effects of the Invention]

[0016] According to the present invention, a sheet-fed printing press can be provided that, when switching the paper discharge position from the upstream paper discharge holding section to the downstream paper discharge holding section, can reliably discharge the last sheet before switching to the upstream paper discharge holding section regardless of the sheet's vertical size. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic side view of an entire printing press. [Figure 2] FIG. 4 is a side view of a first discharged paper holding section provided in the paper discharge section. [Figure 3] FIG. 2 is a plan view of a first discharged paper holding section provided in the paper discharge section. [Figure 4] 3 is a diagram showing the upstream guide portion and the downstream guide portion in FIG. 2 in their operating positions. [Figure 5] 10 is a plan view of a first discharged paper holding section in the discharge section with the upstream guide section and the downstream guide section in the operating position. FIG. [Figure 6] FIG. 2 is a plan view of a first fan device provided in a paper discharge unit. [Figure 7] FIG. 10 is a side view of the main part showing the relationship between the paper release cam and the paper discharge gripper. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1 shows a sheet-fed printing press (hereinafter referred to as printing press) 1. This printing press 1 includes a paper feed section 2 for feeding printing paper sheets one by one from a pile table via a feeder or the like, a printing section 3 for printing on the sheets supplied one by one from the paper feed section 2, and a paper discharge section 4 for receiving and discharging the sheets printed by the printing section 3. In this embodiment, the printing section 3 includes four printing units 3A to 3D capable of printing in four colors, but may also include printing units for any number of colors other than four, such as one color or two or more colors. Furthermore, the printing press 1 may also include a coating device for applying varnish, for example.

[0019] Printing unit 3A is equipped with a paper feed cylinder 2A, a plate cylinder 31, a blanket cylinder 32, and an impression cylinder 33. Each of printing units 3B to 3D is equipped with a plate cylinder 31, a blanket cylinder 32, an impression cylinder 33, and a transfer cylinder (also called an intermediate cylinder) 34. Although not shown, paper feed cylinder 2A is equipped with a gripper at one circumferential position that grips a sheet with a gripper base and a claw. Furthermore, impression cylinder 33 and each transfer cylinder 34 are so-called double cylinders, and although not shown, each impression cylinder 33 and each transfer cylinder 34 is equipped with grippers at two circumferential positions that grip a conveyed sheet with a gripper base and a claw.

[0020] The paper discharge section 4 includes a quality inspection device 41 that inspects the printing quality of printed sheets, a plurality (two in this embodiment) of first and second discharge holding sections 42 and 43 that each hold a stack of multiple sheets (first discharge pile, second discharge pile), a paper discharge gripper 44 that transports the sheets to the discharge holding sections 42 and 43, and a paper holder 45 that contacts the head of the transported sheets, and is equipped with a paper discharge device 46 that can switch between the first discharge holding section 42 or the second discharge holding section 43 as the discharge target between the two first and second discharge holding sections 42 and 43. The switching between the first and second discharged paper holding sections 42, 43 by the discharge device 46 is effected, for example, by a signal sent from a button (not shown) on an operation panel (not shown) on the printing press to the control section (not shown) before printing, so that sheets judged to be "good" are discharged to the first discharged paper holding section 42 and sheets judged to be "bad" are discharged to the second discharged paper holding section 43, as described below.

[0021] The quality inspection device 41 is equipped with a quality inspection camera 41A that captures an image of a printed sheet. The image captured by the quality inspection camera 41A is sent to a control unit (not shown), which compares the captured image with a pre-entered image that has been determined to be "good" to determine whether the sheet is good or bad. If the sheet is determined to be "good," it is discharged to a first discharged sheet holding unit 42, and if the sheet is determined to be "bad," it is discharged to a second discharged sheet holding unit 43.

[0022] The first and second discharged paper holding units 42, 43 include mounting tables 42A, 43A that hold a discharged pile of stacked sheets, and chains 42B, 43B that suspend and support the mounting tables 42A, 43A. The mounting tables 42A, 43A can be raised and lowered by actuators (not shown). Based on a signal from a detection unit that detects the height of the top surface of the topmost sheet in the discharged pile, the actuators are driven continuously or stepwise to lower the mounting tables 42A, 43A so that the height of the top surface of the discharged pile remains approximately constant as the sheets are stacked. This ensures that the distance that the sheets fall from the discharged paper gripper 44 to the discharged paper pile remains approximately constant.

[0023] Above the first and second discharged paper holders 42, 43, there are provided a first fan device 47 (see FIG. 6) and a second fan device (not shown, having the same configuration as the first fan device) for pressing the transported paper sheets downward. The first fan device 47 has five fan units 47U, each with five fans 47A in the width direction, arranged in the transport direction (for a total of 25 fans 47A). The first fan device 47 and the second fan device are always operating while the paper sheets are being transported.

[0024] The paper discharge grippers 44 are mounted at equal intervals on an endless chain 44C wound around multiple sprockets (not shown) (see FIG. 1, in which only a portion (three) of the paper discharge grippers 44 are shown). As shown in FIG. 7, each paper discharge gripper 44 is configured by a plurality of grippers 44G, each equipped with a claw 44A and a claw base 44B for receiving a sheet from the printing unit 3, arranged at intervals in the width direction of the sheet. Each gripper 44G also has a spring (not shown) that biases the claw 44A toward the claw base 44B. The gripper 44G holds the head of the sheet. By running the endless chain 44C, the multiple paper discharge grippers 44 circulate from upstream to downstream in the conveying direction above the first and second paper discharge holders 42 and 43.

[0025] The discharge gripper 44 also has a cam follower 44D (see FIG. 7) for opening the gripper 44G. As shown in FIG. 7, when the discharge gripper 44 moves in the direction of the arrow, the cam follower 44D of the discharge gripper 44 selectively comes into contact with and is pushed down by the lower surface 44e of a paper release cam 44E provided above and downstream of each of the first and second discharged paper holding sections 42, 43. This causes the claw 44A to rotate toward the opening side, releasing the paper sheet that the discharge gripper 44 had been holding.

[0026] The paper holders 45 are located downstream of each of the two first and second paper discharge holding sections 42, 43, and are provided with multiple paper holders along the axial direction of a rotatable rotation shaft 5.By rotating the shaft using an air cylinder not shown, the paper holders 45 can be switched between a state in which they stand up and abut against the front end of the paper sheet, guiding the paper sheet below the first paper discharge holding section 42 (the state shown by the solid line in Figure 2), and a state in which they lie down downstream and do not guide the paper sheet into the first paper discharge holding section 42 (the state shown by the dotted line in Figure 2).

[0027] The first discharged paper holding unit 42, which is located upstream in the conveying direction, is equipped with a paper guide 48 for guiding the paper sheets, and an air outlet 49 for blowing air onto the paper sheets traveling above the first discharged paper holding unit 42. Each of the first and second discharged paper holding units 42, 43 is also equipped with a vacuum suction wheel 40 that brakes the traveling speed and controls the posture of the paper sheets as they fall.

[0028] <Vacuum suction vehicle> The vacuum suction car 40 has a well-known configuration and is installed at an upstream position in each of the first and second discharged paper holding sections 42, 43. The vacuum suction car 40 rotates while adsorbing the falling paper sheet that has been released from the discharged paper gripper 44 by the paper release cam 44E, thereby slowing the traveling speed of the paper sheet relative to the transport speed of the discharged paper gripper 44 and suitably controlling the posture of the paper sheet moving onto the discharged paper pile.

[0029] <Paper guide> The paper guide 48 is configured to be able to move forward and backward in the conveyance direction relative to the first discharged paper pile H, which is the discharged paper pile of the first discharged paper holding section 42 located upstream. The paper guide 48 that has advanced onto the first discharged paper pile H guides the sheets toward the second discharged paper holding section 43 while preventing the tails of the sheets discharged to the second discharged paper holding section 43 from descending toward the first discharged paper pile H.

[0030] The paper guide 48 includes an upstream guide portion 48A located upstream of the first discharged paper holding portion 42 and a downstream guide portion 48B located downstream. The upstream guide portion 48A is provided on the vacuum suction car 40 side and moves horizontally between an operating position (see FIGS. 4 and 5) where it advances above the first discharged paper pile H held by the first discharged paper holding portion 42 as the first air cylinder 48a extends, and a retracted position (see FIGS. 2 and 3) where it retreats upstream from above the first discharged paper pile H as the first air cylinder 48a retracts. The downstream guide portion 48B is provided on the paper support 45 side of the first discharged paper pile H and moves horizontally between an operating position (see FIGS. 4 and 5) where it advances above the first discharged paper pile H as the second air cylinder 48b extends, and a retracted position (see FIGS. 2 and 3) where it retreats downstream from above the first discharged paper pile H as the second air cylinder 48b retracts. As shown in FIGS. 3 and 5, the upstream guide portions 48A are arranged at two locations in the width direction, and the downstream guide portions 48B are arranged at four locations in the width direction. Both guide portions 48A, 48B have a constant horizontal movement amount and are cantilevered when advancing. Both guide portions 48A, 48B are long in the conveyance direction, and the upper surfaces 48c that guide the sheets are horizontal. As shown in FIG. 4, both guide portions 48A, 48B have a smaller (thinner) vertical dimension on the advancing direction side (leading end side) 48d than on the retreating direction side (base end side) 48e. Because the advancing direction side 48d of the paper guide 48 is thin, it is less likely to get caught on the sheets being discharged into the first discharged paper holder 42 than if the guide portions 48A, 48B were thick and had a constant vertical dimension. Both guide portions 48A, 48B are made of a synthetic resin, such as monomer cast nylon (MC nylon (registered trademark)). When printing thick sheets, the sheets have rigidity, so there is no risk of the trailing edge of the sheet drooping during transport by the discharge gripper 44, damaging the sheets on the upstream first discharged sheet holding section 42 (first discharged sheet pile H). In this case, the upstream guide section 48A may not be used.

[0031] <Air jet section> 2 and 4, the air ejection unit 49 is a spray nozzle made of a metal pipe that is roughly V-shaped in side view. The air ejection unit 49 is located downstream of the upstream end of the first ejected paper pile H held by the upstream first ejected paper holding unit 42 and upstream of the paper holder 45 provided on the first ejected paper holding unit 42, and is located above the movement path of the ejected paper gripper 44 and the forward and backward movement path of the paper guide 48. The air ejection unit 49 is located below the first fan unit 47. The air ejection unit 49 ejects air in a direction toward the upper surface of the upstream end of the first ejected paper pile H, and specifically, is inclined upstream at a predetermined angle relative to the downward direction (the predetermined angle θ shown in FIG. 2 is approximately 70°, but any angle between 60° and 75° is preferable). As shown in FIG. 6, the air blowing units 49 are arranged at four locations in the width direction within the minimum paper width. The air blowing units 49 are located near the tips of four supply pipes 49A extending in the conveyance direction between the fans 47A, 47A. Specifically, the air blowing units 49 are installed between the row of fans 47A located most downstream in the conveyance direction and the row of fans 47A located one row upstream from the row of fans 47A located most downstream in the conveyance direction. The outlets 49a (see FIG. 6) of the four air blowing units 49 are located at the same position in the conveyance direction. The outlets 49a of the four air blowing units 49 are also located at the same vertical position, slightly above the movement trajectory of the paper discharge gripper 44. An air source (compressor, not shown) is connected to the four supply pipes 49A via solenoid valves (not shown). A blowing control unit (not shown) that controls the operation timing is connected to the solenoid valves. The blowing control unit opens an electromagnetic valve so that air blown from the outlet 49a of the air blowing unit 49 is blown onto the tail end (upstream end) of a sheet of paper whose tail has escaped from the vacuum suction car 40, and closes it after a predetermined time.

[0032] As shown in FIG. 2, the air blowing direction of the air blowing unit 49 toward the upper surface of the upstream end of the first discharged pile H is downward and inclined toward the upstream side. This delays the timing at which the discharged paper gripper 44 reaches a position that blocks the blown airflow, compared to a configuration in which air is blown directly downward from a position directly above the upper surface of the upstream end of the first discharged paper pile H. This allows the timing at which the blowing ends (the timing at which the solenoid valve closes) to be further delayed, making it possible to set a longer blowing period (blowing time). Furthermore, since the air blowing range toward the upper surface of the upstream end of the first discharged paper pile H is expanded, sheets of various sizes can be accommodated. Specifically, sheets of various conveying direction lengths can be accommodated without changing the conveying direction position of the air blowing unit 49. Furthermore, since the air blowing unit 49 is positioned upstream of the paper holder 45, the distance between the air blowing unit 49 and the upper surface of the upstream end of the first discharged paper pile H is smaller than when the air blowing unit 49 is positioned downstream of the paper holder 45, and this makes it possible to suppress a decrease in the flow speed of the air blown against the upper surface of the upstream end of the first discharged paper pile H. Note that when paper is discharged only to the first discharged paper holding unit 42, air may be blown from the air blowing unit 49 against all sheets delivered to the first discharged paper pile H.

[0033] 2 and 3 show the states in which maximum-sized sheets P1 and P2 are being transported by the discharge grippers 44, 44, respectively. In this manner, when the following discharge gripper 44 approaches the tail end of the sheet P1 being transported by the preceding discharge gripper 44, even when the preceding sheet P1 is discharged to the first discharge holding section 42 and the following sheet P2 is discharged to the second discharge holding section 43, air can be reliably blown onto the tail end of the sheet P1 from the air blowing section 49 configured as described above. This allows the tail end of the sheet P1 to immediately descend downward, preventing the paper guide 48, which advances to its operating position above the first discharge pile H to guide the sheet P2 to the second discharge holding section 43, from colliding with the descending sheet P1.

[0034] In this embodiment, the air ejection unit 49 is disposed at a position coinciding with the upstream guide unit 48A in the width direction of the sheet transported by the ejection gripper 44. With this configuration, the airflow blown by the air ejection unit 49 can more quickly move the tail end of the sheet in the range corresponding to the upstream guide unit 48A downward toward the first ejection pile H. This can reliably prevent the final sheet ejected to the first ejection holding unit 42 before the ejection position is switched from the first ejection holding unit 42 to the second ejection holding unit 43 from getting caught on the upstream guide unit 48A advancing onto the first ejection pile H as it moves downward toward the first ejection pile H. The present invention is particularly suitable for thin sheets (specifically, those having a thickness of less than 0.2 mm).

[0035] The blowing control unit normally controls the blowing operation of the air blowing unit (blow nozzle) 49 to be performed on the last sheet discharged to the first discharged sheet holding unit 42 before the discharge position is switched from the first discharged sheet holding unit 42 to the second discharged sheet holding unit 43, but may also control the blowing operation to be performed on all sheets discharged to the first discharged sheet holding unit 42. By performing the blowing operation on all sheets, the trailing ends of the sheets stacked in the first discharged sheet pile H become flat immediately, improving sheet alignment in the first discharged sheet holding unit 42. The blowing control unit may also be configured to automatically control whether or not to perform the blowing operation of the air blowing unit (blow nozzle) 49 depending on the sheet thickness or conveying speed.

[0036] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0037] In the above embodiment, four air ejection parts 49 are provided, but two or three may be provided.

[0038] Furthermore, in the above embodiment, two discharged paper holding units 42 and 43 are provided, but any number of discharged paper holding units, three or more, may be provided.

[0039] Furthermore, the air source for the air blowing unit 49 shown in the above embodiment may be shared for both moving the paper guide 48 back and forth and for blowing air from the air blowing unit 49. The air pressure can be adjusted (reduced) midway through the air piping that sends the air. [Explanation of symbols]

[0040] 1...printing press, 2...paper feed section, 2A...paper feed cylinder, 3...printing section, 3A to 3D...printing unit, 4...paper discharge section, 5...rotating shaft, 31...plate cylinder, 32...blanket cylinder, 33...impression cylinder, 34...transfer cylinder, 40...vacuum suction car, 41...quality inspection device, 41A...quality inspection camera, 42, 43...first and second discharge holding sections, 42A, 43A...loading table, 42B, 43B...chain, 44...discharge gripper, 44A...claw, 44B...claw base, 44C...endless chain, 4 4D...cam follower, 44E...cam, 44G...gripper, 44e...lower surface, 45...paper holder, 46...paper discharge device, 47A...fan, 47U...fan unit, 48...paper guide, 48A...upstream guide section, 48B...downstream guide section, 48c...upper surface, 48d...advance direction side, 48e...retraction direction side, 49...air jet section (blowing nozzle), 49A...supply pipe, 49a...blowing port, H...first discharge pile, P1, P2...sheets, θ...angle

Claims

1. a paper discharge device including a plurality of discharged paper holding sections each holding a discharged paper pile in which a plurality of sheets are stacked, a discharged paper gripper transporting the sheets to the discharged paper holding sections, and a paper stopper against which the heads of the transported sheets come into contact, and capable of switching the discharged paper holding section to which the paper is to be discharged from among the plurality of discharged paper holding sections; a paper guide that guides the paper sheet in the paper ejection holding unit that is located relatively upstream in the conveyance direction among the plurality of paper ejection holding units; an air blowing unit that blows air onto a sheet being transported above one of the plurality of discharged paper holding units that is located relatively upstream in the transport direction; Equipped with the discharged paper gripper circulates above the plurality of discharged paper holding units from the upstream side to the downstream side in the conveying direction, grips the head of the paper sheet to convey the paper sheet downstream, and releases the paper sheet being conveyed above the discharged paper pile to be discharged, the paper holder is located downstream of each of the plurality of paper discharge holding units, and guides the paper sheets released from the paper discharge grippers onto the paper discharge piles held by each of the paper discharge holding units; the paper guide is configured to be able to advance and retreat along the conveying direction, and guides the paper sheet to the paper discharge holding section located relatively downstream while preventing the paper sheet from descending toward the paper discharge holding section located relatively upstream, A sheet-fed printing press in which the air ejection section is located downstream of the upstream end of the discharged paper pile held by the discharged paper holding section, which is located relatively upstream, and upstream of the paper holder provided on the discharged paper holding section, and is positioned above the movement trajectory of the discharged paper gripper and the forward and backward movement trajectory of the paper guide, and the direction of air ejection is toward the top surface of the upstream end of the discharged paper pile.

2. The paper guide has an upstream guide portion located on the upstream side of each of the plurality of discharged paper holding portions and a downstream guide portion located on the downstream side, The sheet-fed printing press according to claim 1 , wherein the air ejection section is disposed at a position coinciding with the upstream guide section in a width direction of the sheet transported by the discharge gripper.

3. 3. The sheet-fed printing press according to claim 1, wherein the paper guide has a vertical dimension smaller on the advancing side than on the retreating side.

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