JP4452284B2 - Sheet-fed printing press - Google Patents

Description

  The present invention is a sheet-fed printing provided with an intermediate cylinder for a sheet-fed printing machine that is installed after the printing unit and regulates the running posture of a sheet transferred from a pre-process printing unit or the like and stably transfers the sheet. Related to the machine.

In recent years, various types of double-sided printing machines for printing on both front and back sides have been proposed and put into practical use.
The double-sided printing machine illustrated in FIG. 9 exemplifies a printing apparatus that prints one color on both the front and back sides of the sheet 4. In this printing machine, a set of back surface printing apparatuses 1 is disposed below the upstream side of the sheet travel path, and a set of front surface printing apparatuses 2 is disposed above the downstream side of the sheet travel path.

In addition, from the sheet supply device 19, the feeder board unit 20, two sets of intermediate cylinders 3 a and 3 b that are installed in the middle of the back surface printing device 1 and the front surface printing device 2 and sequentially transfer the sheets downstream, the paper discharge device 21, etc. It is configured.
The sheet discharge unit 21 includes a sheet conveying device 22 and a sheet stacking device 23 provided below the downstream end of the sheet conveying device.

The sheet supply device 19 stacks the sheets 4 to be printed on the sheet feeding table 30 and sequentially supplies the sheets 4 one by one from the uppermost sheet 4 corresponding to the consumption speed (machine speed) associated with printing. It is a device to do.
The feeder board unit 20 functions to transfer the sheets 4 sequentially sent out from the sheet supply device 19 to the first intermediate cylinder 24 arranged in the introduction unit of the back surface printing device 1.

The sheet 4 is transferred from the first intermediate cylinder 24 to the second intermediate cylinder 25 and further to the impression cylinder 5a of the back surface printing apparatus 1 for printing. Subsequently, after being sequentially conveyed through the intermediate cylinders 3a and 3b, the sheet is transferred to the impression cylinder 5b of the surface printing apparatus 2 located downstream, and the surface is printed.
The printing apparatus 2 (or 1) includes a plate cylinder 34, a blanket cylinder 35, and an impression cylinder 5 on which an ink reservoir 31, an ink roller group 32, and a printing plate 33 are wound, as shown in FIG. The ink 18 supplied to the ink reservoir 31 is appropriately kneaded in the process of sequentially transferring the ink roller group 32 and transferred to the plate 33 as an ink film. Thereafter, the pattern is transferred to the outer peripheral surface of the downstream blanket cylinder 35 as a pattern.

At the same time, dampening water is also supplied from the dampening water device 36. After that, the image is transferred to the surface of the sheet 4 running between the blanket cylinder 35 and the impression cylinder 5 to complete predetermined printing.
Here, although the example which provided the back surface printing apparatus 1 and the surface printing apparatus 2 respectively 1 each was shown, several sets of back surface printing apparatuses 1 and / or surface printing apparatuses 2 from which an ink color differs along a sheet | seat running direction are shown. Some printing machines perform multicolor printing in parallel. In any case, the number of installed printing apparatuses 1 and 2 is appropriately selected.

  The sheet 4 that has been printed by the above is transferred from the impression cylinder 5b of the final printing device 2 to the sheet conveying device 22 of the paper discharge device 21, that is, the chain gripper provided in the endless chain 28 driven by the paper discharge shaft 27. It is gripped and conveyed to the sheet stacking device 23 and stacked on the sheet discharge table 29 of the sheet stacking device 23. Subsequently, when a predetermined amount is stacked, it is carried out to the outside.

The ink 18 on the sheet printing surface is gripped and conveyed by the gripper of the endless chain 28 that travels by winding the discharge shaft 27 from the impression cylinder 5b after the front surface printing on the outer peripheral surface portion of the intermediate cylinder 3b after the back surface printing. On the way, it is dried by the drying device 17.
Ink used for printing in a sheet-fed printing machine is often ink that dries and cures in response to UV (ultraviolet rays), and therefore is often equipped with a UV drying device that irradiates ultraviolet rays. However, it is desirable to provide a drying device corresponding to the characteristics (properties) of various inks used.

The conventional sheet-fed printing press is configured as described above, but the effect of the drying device 17 in the intermediate cylinder 3b for transferring the sheet 4 to the front surface printing device 2 after the printing by the back surface printing device 1 is completed. Does not function sufficiently, causing problems such as drying unevenness such as uneven drying, and stains or scratches on the printed surface.
Japanese Utility Model Publication No. 2-5951 discloses a paper feeding cylinder that feeds a sheet to various downstream cylinders while adsorbing the sheet. The paper feeding cylinder includes an air tank provided at the cylinder end, a plurality of suction ducts connected to the air tank and extending in the cylinder axis direction and provided with a phase shift in the circumferential direction. Each suction duct is configured with a suction hole drilled from the body circumference surface, and by operating an external air intake device connected to the air tank, the sheet can be sucked by the suction hole. It has become.

  In this paper feeding cylinder, a shutter plate is inserted between the air tank and the suction duct. A plurality of shutter plates are prepared in advance, and each shutter plate has through holes that match different suction ducts. Then, by selecting and using an appropriate one of the shutter plates, a predetermined suction duct is selectively selected as an air tank from among a plurality of suction ducts that are provided with their phases shifted in the circumferential direction. The sheet bottom of the sheet can be adsorbed by a suction hole at an appropriate position according to the size of the sheet.

However, according to this technology, the shutter plate must be replaced every time the size of the sheet is changed. The shutter plate is attached by inserting the shutter plate into a predetermined portion of the paper feed cylinder and fastening it with a bolt.
The object of the present invention is to solve these problems.

  In other words, the object of the present invention is to easily change the setting of the apparatus even if the size of the sheet is changed, to suppress sheet flickering, and to cause poor drying, dirt or scratches on the printing surface, etc. It is an object of the present invention to provide a sheet-fed printing machine that can prevent the occurrence of the problem.

The invention of the present application (Claim 1) includes a back surface printing device that performs printing on the lower surface of the traveling sheet and a front surface printing device that performs printing on the upper surface of the traveling sheet along the traveling path of the sheet, A sheet-fed printing machine provided with a plurality of intermediate cylinders that are installed in the middle between the back surface printing apparatus and the front surface printing apparatus and convey sheets printed therebetween, wherein at least one of the intermediate cylinders has a suction function. a suction-type intermediate cylinder having said suction type in the transfer cylinder is closely opposed only set the d a shower, the air shower, air injection port for injecting air from below to the peripheral surface of the suction type intermediate cylinder a a plurality in the axial direction of the suction type intermediate cylinder, the strength of the air injected from the air injection port is set to be weaker toward the axial end portion from the axial center of the suction-type intermediate cylinder , the suction-type intermediate which receives the injected air The rear portion of the sheet to be the transport downward as extending along the cylinder surface to be sucked and held on the suction type intermediate cylinder, a sheet-fed printing press.

The back surface printing device and the front surface printing device are arranged in this order from the upstream side in the sheet running direction, and the back surface printing quality of the sheet is inspected below the suction- type intermediate cylinder to which the sheet is delivered from the back surface printing device. It is preferable that imaging means for imaging the back surface of the sheet is provided (claim 2).
It is preferable that a drying device is provided on the downstream side of the air shower in the sheet traveling direction so as to face and face the suction-type intermediate cylinder.
It is preferable to provide a rod-shaped sheet guide for guiding the sheet conveyed by the suction-type intermediate cylinder on the downstream side in the sheet running direction of the air shower.

According to the sheet-fed printing press of the present invention, when the suction-type intermediate cylinder sucks the sheet to the peripheral surface, the sheet can be extended not only in the sheet flow direction but also in the sheet width direction. Can be suppressed . For this reason, when this suction-type intermediate cylinder is disposed so as to face the drying device, the drying effect of this drying device can be made to function sufficiently, and drying defects such as drying unevenness can be suppressed. It is possible to prevent the printing surface from becoming dirty or scratched by preventing contact with the apparatus.

  In addition, there is provided switching means for selectively switching the connection between the suction box and the suction force applying means, and using this switching means, suction force is applied to a plurality of suction boxes installed at mutually different rotational positions. Can be switched. Therefore, the operation of adjusting the sheet suction position in the intermediate cylinder according to the sheet size can be easily performed by operating the switching means in order to stably suck the paper bottom.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In addition, the same code | symbol is attached | subjected about the part same as the part mentioned previously by the prior art. Moreover, these figures and description illustrate this invention, and do not restrict | limit the scope of the present invention. It goes without saying that other embodiments may belong to the category of the present invention as long as they match the gist of the present invention.

Since the basic configuration of the sheet-fed double-sided printing machine according to the present invention is the same as that of the sheet-fed double-sided printing machine in the prior art described above, a duplicate description is omitted.
(A) First Embodiment FIGS. 1 to 4 schematically illustrate a first embodiment of the present invention.
FIG. 1 is a schematic side view showing the overall configuration of the sheet-fed printing press, FIG. 2 is a transverse sectional view showing the structure of an intermediate cylinder (suction cylinder), and FIG. 3 is an axial sectional view. FIG. 4 shows an example of the arrangement of the suction holes.

In this embodiment, the intermediate cylinder 3b among the four intermediate cylinders 3a to 3d for sheet-fed printing presses provided between the back surface printing apparatus 1 and the front surface printing apparatus 2 in FIG. The traveling sheet 4 is configured to be stably transferred by sucking and holding the traveling sheet 4 on the outer peripheral surface of the intermediate cylinder 3b.
Specifically, as shown in FIGS. 2 and 3, the intermediate body 3 b includes a cell (main body) 11, a rotating shaft 14 that integrally rotates the cell 11, and a suction shaft 13. Then, a suction box 15 having a suction function is provided on a part of the outer peripheral surface of the main body 11, and by this suction box 15, the tail, that is, the rear part of the traveling seat 4 is attracted and held on the outer peripheral surface, As described above, the sheet 4 is stably transferred.

In this embodiment, as shown in FIGS. 2 and 3, suction boxes 15 (15a, 15b) are provided at two locations on the intermediate body 3b.
The suction boxes 15a and 15b are connected to the suction holes 38a and 38b in the suction shaft 13 through the connecting pipes 6a and 6b, respectively, and are moved in the axial direction by an air cylinder (actuator) 37 to switch the intake location (switching). Means) Connected to the suction pipe 9, the control valve 8 and the suction device (suction force applying means) 10 which is an air suction source via the opening 7a or 7b of 7, and the suction operation and non-operation can be arbitrarily performed. It can be set. As shown in FIG. 4, a plurality of air suction holes 16 are formed in the outer peripheral surfaces (surfaces forming the outer peripheral surface of the cylinder) of the suction boxes 15a and 15b. When 10 is operated, the inside of the suction box 15 becomes negative pressure, and external air can be sucked through these air suction holes 16. For this reason, the sheet | seat 4 which contacts an outer peripheral surface is conveyed in the adsorbed state, and is sent into the following intermediate | middle cylinder 3c. Accordingly, the sheet 4 is dried by the drying device 17 in a state in which there is no fluctuation of the sheet 4 and is fed into the next intermediate cylinder 3c.

In this embodiment, two suction points, that is, suction boxes 15 are provided. However, the present invention is not limited to this, and one or a plurality of suction boxes 15 can be installed.
The suction timing starts when the tail of the sheet 4 is transferred from the intermediate cylinder 3a to the intermediate cylinder 3b, and is released before the transfer from the intermediate cylinder 3b to the intermediate cylinder 3c.

However, such adsorption timing and the number of suction boxes are appropriately set according to various conditions, and can be determined by trial and error in advance by performing tests and simulations to obtain stable adsorption performance. Useful above.
If the suction timing and number of suction boxes are inappropriate, the effect of preventing the sheet 4 from fluttering may be insufficient. On the other hand, if the suction timing is set too wide or the number of suction boxes is too large, it is useless. Air can be aspirated. In addition, the waste of equipment increases. At the same time, the amount of air sucked can be determined by trial and error.

FIG. 4 shows an example of the arrangement pattern of the suction holes 16 on the surface of the suction box. The number and shape of the suction holes 16 can be appropriately determined by a test or the like.
In this way, according to the present invention, if the suction box is provided in the intermediate cylinder, the sheet 4 can be prevented from being shaken (flutter). As a result, the effect of the drying device 17 can be stably and sufficiently exerted, such as uneven drying. Insufficiency of drying can be prevented, and stains and scratches that tend to occur on the printed surface can be prevented.

Further, the suction boxes 15a and 15b are selectively used, and the suction boxes 15a and 15b are switched by moving the switching valve 7 by the operation of the air cylinder 37.
That is, in FIG. 3, when the drive shaft of the air cylinder 37 is in the retracted A position (state shown), the suction port 38a formed in the suction shaft 13 is an opening formed in the switching valve 7. In accordance with the portion 7a, only the suction box 15a is connected to the suction device 10 via the switching valve 7 to be in a suction state, while the suction shaft 13 is in a state where the drive shaft of the air cylinder 37 is in the extended B position. The suction port 38b drilled in the opening coincides with the opening 7b drilled in the switching valve 7, so that only the suction box 15b is connected to the suction machine 10 via the switching valve 7 and is brought into a suction state. ing.

For example, the tail of the sheet 4 can be stably adsorbed by using the suction box 15b when the sheet length is short and using the suction box 15a when the sheet length is long.
The actuator for operating the switching valve 7 is not limited to an air cylinder, and various types such as an electric motor can be used. When an electric motor is used as the actuator, the switching valve 7 can be moved using, for example, a pinion rack mechanism.

  The suction start and release timing is determined by the suction port angle θ and its position in FIG. The position can be changed and set by holding the switching valve 7 so as to be capable of rotational adjustment. As shown in FIG. 2, the openings 7 a and 7 b drilled in the switching valve 7 are formed in an arc shape along the peripheral surface of the switching valve 7, and the suction shaft 13 is connected to the arc-shaped switching valve 7. Suction is performed by the suction boxes 15a and 15b within a range where the suction ports 38a and 38b coincide. The suction port angle θ is the arc angle of the openings 7a and 7b.

Further, as described above, by selectively using the suction boxes 15a and 15b according to the sheet length, there is an advantage that the sheet 4 can be stably adsorbed regardless of the sheet length. In addition, there is an advantage that the suction boxes 15a and 15b can be easily and automatically switched only by controlling the operation of the air cylinder.
The form of the suction box is not limited to the above, and any known system can be adopted.

(B) Second Embodiment FIG. 5 is a diagram showing a second embodiment of the present invention, and schematically illustrates a state in which an intermediate body according to the present invention is installed in a sheet-fed printing press. .

In FIG. 5, in a double-sided printing machine configured to perform printing for one color on each of the front and back sides, the intermediate cylinders 3b and 3d between the impression cylinder 5a of the back-side printing apparatus 1 and the impression cylinder 5b of the front-side printing apparatus 2 A cylinder is installed, and a drying device 17 is installed in close proximity to the intermediate cylinder. Basic printing functions (actions and effects) are the same as those described in the prior art.
In FIG. 5, the drying device 17 is disposed at two locations, and the corresponding two pairs of intermediate cylinders 3b and 3d are configured as suction intermediate cylinders, so that the fluttering of the sheet being dried can be suppressed. In addition to the effects described with respect to the form, the drying ability of the printing surface can be increased, so that the printing speed can be improved and the productivity can be improved.

  If the diameter of the intermediate cylinder 3 corresponding to the drying device 17 is formed large, it is possible to increase the sheet area that can be irradiated at the same time, and it is possible to further increase the drying function (efficiency).

(C) Third Embodiment FIGS. 6 to 8 schematically illustrate a sheet-fed printing press according to a third embodiment of the present invention.
6 is a schematic cross-sectional view from a side view, FIG. 7 is a schematic perspective view showing the intermediate cylinder and air injection means extracted, and FIG. 8 is a view for explaining a preferable range of injection positions of the air shower 50 It is a typical side view of an intermediate body.
As shown in FIG. 6, the sheet-fed printing machine according to the present embodiment is different from the sheet-fed printing machine according to the first embodiment in that an air shower (air jetting unit) 50 and an image sensor (for example, a CCD camera or the like) , A detection device such as a COMS type or an infrared sensor) 60 is added.

  The air shower 50 is provided with the air injection port 50 a facing the intermediate cylinder 3 b, and the drying device 17 is provided on the intermediate cylinder 3 b so as to face each other across the travel line of the seat 4. As shown in FIG. 7, the air shower 50 is provided with a plurality of the air injection ports 50 a along the axial direction of the intermediate body 3 b, and the air shower 50 is connected to an external air blower 53 via an air pipe 51. By operating the air blower 53, air can be continuously injected from the air injection port 50a over substantially the entire width of the intermediate cylinder 3b. Of course, air may be ejected by the air shower 50 only when the seat 4 is located in the air ejection region of the air shower 50.

  Further, the air injection port 50a changes the distance between the air injection ports 50a and the diameter of the air injection port 50a according to the axial direction of the intermediate cylinder 3b, that is, the position in the width direction of the seat 4, and the strength of the air is increased in the axial direction of the intermediate cylinder 3b. The sheet 4 becomes weaker from the center toward the end in the axial direction, and the sheet 4 can be extended not only in the sheet flow direction but also in the sheet width direction. Of course, the interval between the air injection ports 50a and the diameter of the injection ports may be constant regardless of the position in the width direction of the seat 4.

The air piping 51 is provided with a pressure control valve 52, and the air injection pressure of the air blower 53 is adjusted by the pressure control valve 52 to a predetermined pressure set according to the paper type and the like. It has become. Further, reference numeral 70 in FIG. 7 is a rod-shaped sheet guide for guiding the sheet 4 conveyed by the intermediate cylinder 3b.
With such a configuration, as shown in FIG. 8, the paper bottom of the sheet 4 conveyed by the intermediate cylinder 3b is extended along the peripheral surface of the intermediate cylinder 3b (this is referred to as a paper extending effect). (In FIG. 8, for the sake of convenience, there is shown a gap between the seat 4 and the intermediate cylinder 3b). Accordingly, it is possible to prevent the sheet 4 from being attracted to the intermediate cylinder 3 in a bent state, and to prevent the sheet 4 from being damaged due to this bending coming into contact with the drying device 17. .

Further, since the sheet 4 comes into close contact with the intermediate cylinder 3b by receiving the jet air from the air shower 50, the sheet 4 can be stably adsorbed by the intermediate cylinder 3b.
Here, it is preferable that the air shower 50 injects air into the predetermined region R in FIG. 8 with respect to the peripheral surface of the intermediate cylinder in order to make the above effect remarkable. The region R is a sheet receiving portion of the intermediate cylinder 3b (where the intermediate cylinders 3a and 3b are close to each other and the intermediate cylinder 3b receives the sheet 4 from the intermediate cylinder 3a) A downward from the angle around the rotation axis C0 of the intermediate cylinder 3b. It is a region within a 45 degree range on the side.

  Now, the image sensor (imaging means) 60 is provided for the intermediate cylinder 3b, and images the printing surface (the opposite side of the adsorption surface) of the sheet 4 adsorbed by the intermediate cylinder 3b. . The imaging information of the image sensor 60 is output to an analysis device (not shown) so that the back side print quality of the sheet 4 can be analyzed and detected. Alternatively, the imaging information may be output to a display device (not shown), and the operator may monitor the back surface print quality using this display device.

Since the sheet-fed printing press as the third embodiment of the present invention is configured as described above, the adsorption of the sheet 4 by the intermediate cylinder 3b can be stabilized, and the advantages of the above-described embodiment are further effective. Can be obtained.
Further, since the back side can be imaged in a stable state where the sheet 4 is adsorbed to the intermediate cylinder 3b, there is also an advantage that the back side print quality of the sheet 4 can be detected with high accuracy based on this imaging.

In addition, in the above-described embodiment, a configuration in which the air shower 50 is not provided, that is, a configuration in which only the image sensor 60 is added to the intermediate cylinder 3b having a suction mechanism is naturally possible.
In the above embodiment, the air shower 50 and the image sensor 60 are provided for the intermediate cylinder 3b. However, the air shower 50 and the image sensor 60 may be provided for the intermediate cylinder 3d.

(D) Others The present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention.
For example, the above description has been made on the intermediate cylinder in front and back printing, but the present invention is not limited to this, and the drying effect of the drying device 17 can be reduced by preventing the sheet 4 from swinging around the intermediate cylinder. Including the case of single-sided printing, as long as it meets the purpose of the present invention to solve problems such as poor drying such as uneven drying and generation of dirt and scratches on the printed surface. It can be applied in any case.

In each of the above embodiments, the back surface printing device 1 and the front surface printing device 2 are arranged in this order from the upstream side in the traveling direction of the sheet 4. Alternatively, the seats 4 may be arranged from the upstream side in the traveling direction.
Further, in the above embodiment, four intermediate cylinders are disposed between the back surface printing apparatus 1 and the front surface printing apparatus 2, but the number of intermediate cylinders between the printing apparatuses 1 and 2 is the same as that of the upper printing apparatus and the subsequent printing apparatus. In this printing apparatus, the number of sheets 4 may be any number that is wound around the impression cylinder as the outer peripheral surface, that is, the printing surface.

It is a figure which shows schematic structure of the sheet-fed double-sided printing machine of the 1st related technique of this invention. It is a cross-sectional view (XX sectional view of FIG. 3) of the intermediate | middle cylinder which modeled the 1st related technique of this invention in model. It is an axial direction sectional view of the middle drum which modeled the 1st related art of the invention in this application. FIG. 4 is a diagram (an arrow view in FIG. 2) illustrating an example of a suction hole arrangement of the intermediate cylinder illustrated in FIGS. 2 and 3. It is a figure shown about the 2nd related technology of this invention, and shows the state which made the sheet | seat printing machine equip | install the intermediate | middle cylinder part which concerns on this invention with a model. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates a sheet-fed printing press according to an embodiment of the present invention, and is a schematic cross-sectional view from a side view. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view illustrating a sheet-fed printing press according to an embodiment of the present invention as a model, with an intermediate cylinder and air ejection means extracted. The air shower concerning the sheet-fed printing machine of one Embodiment of this invention is illustrated in model, and it is a typical side view for demonstrating the preferable range of the effect | action and air injection direction. It is explanatory drawing which shows schematic structure of the conventional sheet-fed double-sided printing machine. It is explanatory drawing of the subject which generate | occur | produces in the intermediate | middle drum part of the conventional sheet-fed double-sided printing machine. It is explanatory drawing of a printing apparatus part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Back surface printing apparatus 2 Front surface printing apparatus 3 (3a, 3b, 3c, 3d) Intermediate cylinder 4 for sheet-fed printing machines Sheet 5 (5a, 5b) Pressure cylinder 6 (6a, 6b) Connection pipe 7 Switching valve (switching means)
7a, 7b Opening 8 Control valve 9 Suction pipe 10 Suction machine (suction force applying means)
11 Cell 12 Inner cylinder 13 Suction shaft 14 Rotating shaft 15 (15a, 15b) Suction box 16 Air suction hole 17 Drying device 18 Ink 19 Sheet supply device 20 Feeder board portion 21 Paper discharge device 22 Sheet transport device 23 Sheet stacking device 24 First intermediate cylinder 25 Second intermediate cylinder 26 Claw device 27 Paper discharge shaft 28 Endless chain 29 Paper discharge table 30 Paper feed table 31 Ink reservoir 32 Ink roller group 33 Printing plate 34 Plate cylinder 35 Blanket cylinder 36 Dampening water device 37 Air Cylinder (actuator)
38 (38a, 38b) Suction port 50 Air shower (air injection means)
50a Air injection port 51 Air piping 52 Pressure control valve 53 Air blower 60 Image sensor (imaging means)
70 sheet guide

Claims (4)

A backside printing device that performs printing on the lower surface of the traveling sheet and a front surface printing device that performs printing on the upper surface of the traveling sheet along the traveling path of the sheet,
A sheet-fed printing press comprising a plurality of intermediate cylinders that are installed in the middle of the back surface printing device and the front surface printing device and convey a sheet printed between them,
At least one of the intermediate cylinders is a suction-type intermediate cylinder having a suction function,
Setting the d A shower in close proximity facing the suction type intermediate cylinder,
The air shower, a plurality of air injection ports in the axial direction of the suction-type intermediate cylinder for injecting air from below to the peripheral surface of the suction type intermediate cylinder, the intensity of air ejected from the air injection port The rear surface portion of the sheet which is set so as to become weaker from the axial center of the suction-type intermediate cylinder toward the axial end and which is conveyed below the suction-type intermediate cylinder which receives the injected air A sheet-fed printing machine, wherein the suction- type intermediate cylinder is sucked and held so as to extend along the line. The back surface printing device and the front surface printing device are arranged in this order from the upstream side in the sheet running direction, and the back surface printing quality of the sheet is inspected below the suction- type intermediate cylinder to which the sheet is delivered from the back surface printing device. The sheet-fed printing press according to claim 1, further comprising imaging means for imaging the back surface of the sheet. The sheet-fed printing press according to claim 1 or 2, wherein a drying device is provided on the downstream side in the sheet running direction of the air shower so as to be close to and opposed to the suction-type intermediate cylinder. The rod-shaped sheet guide for guiding the sheet conveyed by the suction type intermediate cylinder is provided on the downstream side in the sheet traveling direction of the air shower, according to any one of claims 1 to 3. The described sheet-fed printing press.

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