JP2013107296A - Floating prevention device of sheet, sheet printing machine, and floating prevention method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sheet with low rigidity from fluttering while suppressing the floating of the sheet from an outer peripheral surface of an impression cylinder on free end side of the sheet.SOLUTION: When a rubber cylinder 16E is in a cylinder drawn state, while a part from a front end to the middle of the sheet S passes a photographing area 30A, a first sheet pressing device 31 on the upstream side is operated to press the sheet S to the outer peripheral surface of the impression cylinder 17E, and a second sheet pressing device 32 on the downstream side stops the operation. While a part from the middle to a rear end of the sheet S passes the photographing area 30A, the second sheet pressing device 32 is operated to press the sheet S to the outer peripheral surface of the impression cylinder 17E, and the first sheet pressing device 31 stops the operation.

Description

  The present invention is provided in a sheet-fed printing machine, and prevents a sheet-fed sheet from being lifted from the outer peripheral surface of a printing cylinder, a sheet-fed printing machine including the sheet-fed printing machine, and sheet-fed sheet prevention. It is about the method.

In recent years, in a sheet-fed printing press, a technique has been developed in which a print state of a printed material immediately after printing is photographed to inspect the print quality (see, for example, Patent Documents 1 to 4). In each of these Patent Documents 1 to 4, an imaging device (camera) is provided opposite to the impression cylinder of the final printing device on the printing surface to photograph the printing state.
In a sheet-fed printing machine, while feeding the leading end part (sheet side) of a sheet sheet (sheet-like printed sheet, such as a sheet) along the outer peripheral surface of the impression cylinder and the intermediate cylinder by a gripping mechanism In order to perform printing, the rear end portion (butt side) of the sheet is not restrained except at the nip portion between the rubber cylinder (blanket cylinder) and the impression cylinder or the nip portion between the impression cylinder and the intermediate cylinder. Easily lifts from the outer peripheral surface of the intermediate barrel.

When the print quality is inspected from the captured image information, if the distance between the camera lens and the sheet is changed, appropriate image information cannot be obtained, and the print quality cannot be inspected properly.
Therefore, in Patent Documents 1 and 4, for example, as shown in FIG. 8, a camera 30 is provided downstream of the nip NP between the rubber cylinder 16 and the impression cylinder 17, and the impression cylinder near the imaging region 30 </ b> A of the camera 30. The structure which installs the air-type presser 31 which injects air toward the outer peripheral surface of 17 and presses the sheet | seat sheet S against the outer peripheral surface of the impression cylinder 17 is described. In the technique of Patent Document 1, the air-type presser device 31 is operated in accordance with the rotational phase of the impression cylinder 17 so as to inject air into a predetermined range of the sheet S.

  Patent Document 2 discloses an air-type presser device that blows air toward the outer peripheral surface of the impression cylinder on the upstream side and the downstream side in the sheet conveyance direction from the camera axis in the vicinity of the camera imaging region. In addition to the installation, a suction device is provided almost on the photographing axis, and the air blown from the two air-type presser devices is sucked by the suction device so that no air flows outside the photographing area. A technique for suppressing fluttering of a single-wafer sheet due to air sprayed to portions other than the region is described.

Patent Document 3 discloses a roller presser device in which a roller is brought into contact with the outer peripheral surface of the impression cylinder on the upstream side in the sheet conveyance direction with respect to the camera axis in the vicinity of the imaging region of the camera, and the outer periphery of the impression cylinder. A technique is described in which both the air-type presser device that blows air toward the surface is installed to suppress the floating and fluttering of the sheet.
Patent Document 5 describes a technique for adjusting the air flow rate of the pneumatic presser according to thin paper and thick paper as a sheet.

Japanese Patent Laid-Open No. 3-99853 JP 2006-1079 A JP 2008-58004 A JP 2010-188862 A JP 2010-208809 A

  By the way, if the rubber cylinder is inserted and the sheet is sandwiched between the blanket cylinder and the impression cylinder, the free end (rear end) side of the sheet may float from the outer peripheral surface of the impression cylinder. There is no need to make it. However, if the rubber cylinder is removed, the free end (rear end) side of the sheet is lifted from the outer peripheral surface of the impression cylinder, so that it is necessary to prevent lifting by the presser device. However, when using an air-type presser device, increasing the air flow rate (that is, increasing the air pressure toward the outer peripheral surface of the impression cylinder) will tend to cause the free end (rear end) side of the sheet to flutter. It is necessary to prevent the leaf sheet from lifting from the outer peripheral surface of the impression cylinder on the free end (rear end) side and to prevent fluttering.

  Even if the rubber cylinder is inserted and the sheet is sandwiched between the rubber cylinder and the impression cylinder, the portion not sandwiched by the nip of the sheet does not follow the outer peripheral surface of the impression cylinder. In some cases, it may rise from the outer peripheral surface of the trunk. On the other hand, when the rubber cylinder is removed, the air flow rate of the pneumatic presser is not sufficiently high (that is, the air pressure toward the outer peripheral surface of the impression cylinder is not sufficiently high). The end (rear end) side may be lifted from the outer peripheral surface of the impression cylinder.

As described above, when the sheet is lifted or fluttered, appropriate image information is obtained due to a change in the distance between the camera and the sheet even when the printing state of the sheet is photographed by the photographing device (camera). There is also a possibility that print quality inspection cannot be performed properly.
Moreover, such a defect is not limited to the print quality inspection. For example, even when a printing surface printed with UV ink is dried by UV irradiation by a UV-type drying device, if there is a float or fluttering of a sheet to be irradiated with UV, there is a possibility that proper UV drying cannot be performed. .

  The present invention has been devised in view of such a problem, and prevents the sheet from rising from the outer peripheral surface of the impression cylinder on the free end (rear end) side of the sheet, and prevents fluttering. It is an object of the present invention to provide a sheet-fed sheet floating prevention device, a sheet-fed printing machine, and a sheet-fed sheet floating prevention method, which are capable of appropriately performing processing on a printing surface of a sheet.

  In order to achieve the above object, the sheet-sheet float prevention device of the present invention is fed from the nip portion between the impression cylinder and the rubber cylinder of the sheet-fed printing press while holding the front end portion, and the outer peripheral surface of the impression cylinder. The sheet transported along the sheet is a sheet sheet float prevention device that prevents the impression cylinder from floating from the outer peripheral surface at a specific location, and is disposed downstream of the nip portion in the transport direction. A first sheet pressing device that presses the single sheet against the outer peripheral surface of the impression cylinder in a specific region including the specific location, and is disposed downstream of the first sheet pressing device in the transfer direction and upstream of the transfer direction. An air-type second sheet pressing device that presses the sheet to the outer peripheral surface of the impression cylinder in the specific region by injecting air toward the specific area, the first sheet pressing device, and the second sheet pressing device. A control device for controlling the operation of the presser device, wherein the control device is configured to allow the intermediate portion to pass through the specific region from the front end portion of the single-wafer sheet when the rubber cylinder is in the unrolled state. The first sheet pressing device is operated and the second sheet pressing device is stopped. The second sheet pressing device is operated while the rear end portion passes from the intermediate portion to the specific area of the sheet. The first control for stopping the operation of the first sheet pressing device is performed.

  According to this sheet-sheet anti-floating device, when the rubber cylinder is unrolled, the intermediate portion from the front end portion of the sheet is, for example, the reference location of the photographing target of the photographing device or the ultraviolet light of the UV-type drying device. While passing through a specific area including a specific location such as a reference location of an irradiation target (such as an imaging region or an ultraviolet irradiation region), the upstream first sheet pressing device is activated and the downstream second sheet pressing device is deactivated. Therefore, it is possible to prevent the sheet from rising from the outer peripheral surface of the impression cylinder from the front end portion of the sheet. After that, the second sheet pressing device is operated and the first sheet pressing device is deactivated while the rear end portion from the intermediate portion of the single sheet passes through the specific region. Lifting from the outer peripheral surface of the impression cylinder can be prevented without fluttering the part.

In addition, the control device performs the first control when the rubber cylinder is in a barrel-removed state on the condition that the rigidity of the sheet is a low-rigidity sheet (thin paper) having a reference rigidity or less, When the rubber cylinder is in a cylinder-inserted state, it is preferable to implement a second control that stops operation of both the first sheet pressing device and the second sheet pressing device.
In this way, when the sheet is a low-rigidity sheet (thin paper), if the rubber cylinder is in a barreled state, the sheet is sandwiched between the rubber cylinder and the impression cylinder while passing through the nip portion. Therefore, even if the operation of both the first sheet pressing device and the second sheet pressing device is stopped, the sheet can be prevented from lifting from the outer peripheral surface of the impression cylinder without any trouble, and the sheet pressing device is unnecessary. Operation can be prevented.

Further, the control device is provided with the first sheet pressing device and the first sheet pressing device, when the rubber cylinder is in a barrel-removed state, on the condition that the rigidity of the sheet is a high-rigidity sheet (thick paper) higher than a standard rigidity. It is preferable to implement a third control for operating any of the second sheet pressing devices.
When the sheet is a high-rigidity sheet (thick paper) whose rigidity is higher than the standard rigidity and the rubber cylinder is in the unrolled state, the sheet is likely to lift from the outer surface of the impression cylinder due to its own rigidity. By operating both the sheet pressing device and the second sheet pressing device, the air injection amount can be increased and the sheet can be reliably pressed against the outer peripheral surface of the impression cylinder. Lifting from the surface can be prevented.

In addition, the control device may be configured to change the first sheet pressing device when the rubber cylinder is in a retracted state on the condition that the rigidity of the sheet is a high-rigidity sheet (thick paper) higher than a standard rigidity. It is preferable to implement the fourth control that activates and deactivates the second sheet pressing device.
When the sheet is a high-rigidity sheet (thick paper) and the rubber cylinder is in a cylinder-inserted state, the sheet is sandwiched between the rubber cylinder and the impression cylinder while passing through the nip portion. Therefore, since the lift is small, by operating the first sheet pressing device and stopping the second sheet pressing device, the excessive operation of the sheet pressing device is suppressed and the outer surface of the impression cylinder of the sheet-fed sheet is suppressed. Can be prevented from lifting. In the case of a high-rigidity sheet, even if air is jetted toward the surface of the sheet, the sheet does not flutter due to its own rigidity. Further, by stopping the operation of the second sheet pressing device, it is possible to reduce the drying of the rubber cylinder surface due to the air toward the rubber cylinder side.

  The first sheet pressing device is configured as an air-type sheet pressing device that presses the sheet to the outer peripheral surface of the impression cylinder by injecting air toward the surface of the sheet. A rotary valve that switches a supply state of air to the first sheet pressing device of the type and the second sheet pressing device of the air type, and the control device controls the rotation phase of the rotary valve to control the first It is preferable to control the operation of the one sheet pressing device and the second sheet pressing device.

  If the upstream first sheet pressing device is of the air type, the sheet can be prevented from lifting without contact, but in the case of a low-rigidity sheet (thin paper) whose sheet sheet rigidity is below the standard rigidity When air is sprayed toward the surface of the sheet, the sheet tends to flutter from the middle to the rear end. In this regard, from the intermediate portion to the rear end portion of the single sheet, the second sheet pressing device is operated to inject air toward the upstream side in the transfer direction, thereby bringing the single sheet into the outer peripheral surface of the impression cylinder. Since it is pressed, it is possible to prevent lifting from the outer peripheral surface of the impression cylinder without fluttering.

  Further, if the second sheet pressing device is of an air type like the first sheet pressing device and a rotary valve for switching the supply state of air to the first sheet pressing device and the second sheet pressing device is provided, the control is performed. By controlling the rotation phase of the rotary valve, the apparatus can easily control the operation of the first sheet pressing device and the second sheet pressing device with respect to the operation of the first sheet pressing device and the second sheet pressing device. it can.

Furthermore, it is preferable that the air injection amount of the second sheet pressing device is set to be smaller than the air injection amount of the first sheet pressing device.
As a result, when the sheet cylinder is a low-rigidity sheet (thin paper) and the rubber cylinder is in the barrel-extracted state, the second sheet pressing device is operated and specified by injecting air upstream in the transfer direction. In this area, the strength of the air when the sheet is pressed against the outer peripheral surface of the impression cylinder is suppressed, and the possibility of fluttering from the middle part to the rear end of the sheet due to the air injection by the second sheet pressing device is also avoided. Is done.

Further, an imaging device is provided for photographing the printing surface of the sheet for controlling print quality, facing the impression cylinder of the sheet printing machine that performs printing on the printing surface of the sheet. It is preferable.
In the case of a photographing apparatus for print quality control, a high-quality photographed image is required to improve print quality control accuracy, and it is effective to bring the photographing apparatus close to the photographing area. The closer the sheet is, the more the sheet sheet floats or flutters, causing a significant shift from the focus of the photographing apparatus and lowering the image quality and lowering the printing quality control accuracy. However, such a problem is also avoided.

Alternatively, facing the impression cylinder of the sheet-fed printing machine that prints on the printing surface of the sheet, the printing surface of the sheet is dried to dry the UV ink transferred to the printing surface. It is also preferable that a UV-type drying apparatus that irradiates ultraviolet rays is provided.
In the case of a UV-type drying device for drying UV ink transferred to the printing surface of a sheet, it is effective to bring the UV-type drying device close to the ultraviolet irradiation area for efficient ink drying. However, as the UV drying device is brought closer to the ultraviolet irradiation region, the slight lift and fluttering of the sheet will cause contact with the UV drying device and eventually damage to the sheet. Troubles are also avoided.

  Further, the sheet-fed printing press according to the present invention includes an impression cylinder that bites a front end portion of a sheet and holds the sheet along the outer peripheral surface and rotates the sheet to transfer the sheet, and the impression cylinder A sheet-fed printing press having a rubber cylinder that can be switched between a cylinder-inserted state in which ink can be transferred to the printing surface of the sheet-fed sheet and a cylinder-extracted state separated from the impression cylinder. In addition, the sheet-fed sheet float prevention device is provided on the outer periphery of the impression cylinder downstream of the nip portion where the rubber cylinder is nip-engaged with the impression cylinder in the cylinder-inserted state. It is said.

  According to such a sheet-fed printing machine, when printing is performed with the rubber cylinder being unrolled, the middle part from the front end part of the sheet-fed sheet is, for example, a reference location for photographing of the photographing apparatus or UV drying. While passing through a specific area (photographing area or ultraviolet irradiation area, etc.) including a specific location, such as a reference location of the ultraviolet irradiation target of the apparatus, the upstream first sheet pressing device is operated and the downstream second sheet pressing device is operated. Since the stop is performed, it is possible to prevent the sheet from rising from the outer peripheral surface of the impression cylinder from the front end of the sheet. After that, the second sheet pressing device is operated and the first sheet pressing device is deactivated while the rear end portion from the intermediate portion of the single sheet passes through the specific region. It is possible to prevent the impression cylinder from being lifted from the outer peripheral surface without fluttering the portion, and for example, it is possible to appropriately perform photographing with a photographing device of a printed sheet and drying with a UV-type drying device.

  Further, the sheet-fed sheet floating prevention method of the present invention is a sheet fed from the nip portion between the impression cylinder and the rubber cylinder of the sheet-fed printing press while being held at the front end and conveyed along the outer peripheral surface of the impression cylinder. A method of preventing a sheet sheet from floating from the outer peripheral surface of the impression cylinder at a specific location, wherein the sheet sheet is prevented from floating, and when the rubber cylinder is unwound, an intermediate portion extends from the front end of the sheet sheet. While passing through the specific area including the specific location, the sheet is pressed against the outer peripheral surface of the impression cylinder between the specific location and the nip portion upstream of the specific location in the transfer direction, An upstream side sheet pressing process is performed, and while the rear end portion from the middle portion of the single sheet passes through the specific region, the pressure is applied to the single sheet using the air downstream from the specific portion in the transfer direction. Press against the outer peripheral surface of the trunk That is characterized in carrying out the downstream sheet hold-down process.

  According to such a sheet-sheet floating prevention method, when printing is performed with the rubber cylinder being unrolled, the intermediate portion from the front end portion of the sheet is, for example, a reference location of a photographing target of the photographing apparatus or While passing through a specific area (photographing area or ultraviolet irradiation area, etc.) including a specific location such as a reference location for UV irradiation of the UV drying device, the upstream first sheet pressing device is operated and the downstream second sheet pressing is performed. Since the operation of the apparatus is stopped, it is possible to prevent lifting from the outer peripheral surface of the impression cylinder at the intermediate portion from the front end portion of the sheet. After that, the second sheet pressing device is operated and the first sheet pressing device is deactivated while the rear end portion from the intermediate portion of the single sheet passes through the specific region. Lifting from the outer peripheral surface of the impression cylinder can be prevented without fluttering the part.

When the rubber cylinder is unrolled under the condition that the rigidity of the sheet is a high rigidity sheet (thick paper) higher than the standard rigidity, at least the front end portion and the rear end portion of the sheet pass through the specific region. During this time, it is preferable to carry out the upstream sheet pressing process and the downstream sheet pressing process.
When the sheet is a high-rigidity sheet (thick paper) whose rigidity is higher than the standard rigidity and the rubber cylinder is in the unrolled state, the sheet is likely to lift from the outer surface of the impression cylinder due to its own rigidity. By operating both the sheet pressing device and the second sheet pressing device, the air injection amount can be increased and the sheet can be reliably pressed against the outer peripheral surface of the impression cylinder. Lifting from the surface can be prevented.

  According to the sheet-sheet anti-floating device, sheet-fed printing machine, or method for preventing floating according to the present invention, when the rubber cylinder is in the cylinder-unrolled state, the middle portion is, for example, photographed by the photographing apparatus. While passing through a specific area (photographing area or ultraviolet irradiation area, etc.) including a specific location such as a target reference location or a reference location for UV irradiation of the UV-type drying apparatus, the upstream first sheet pressing device is operated and downstream. Since the second sheet pressing device is deactivated, it is possible to prevent the sheet from rising from the outer peripheral surface of the impression cylinder from the front end of the sheet. Further, since the second sheet pressing device is operated and the first sheet pressing device is deactivated while the rear end portion from the middle portion of the single sheet passes through the specific area, the first sheet pressing device is deactivated. Lifting from the outer peripheral surface of the impression cylinder can be prevented without fluttering the part.

It is a block diagram which shows the floating prevention apparatus of the sheet | seat concerning one Embodiment of this invention with the principal part cross section of a double-sided printing machine. It is a side view which shows the double-sided printing machine concerning one Embodiment of this invention. It is an air supply system figure explaining the action | operation of the sheet | seat floating prevention apparatus concerning one Embodiment of this invention. It is sectional drawing of the rotary valve with which the float prevention apparatus of the single wafer sheet concerning one Embodiment of this invention was equipped, (a)-(d) shows each phase state. The air supply state [FIG. 5 (a)] and the rotary valve state [FIG. 5 (b)] according to the float prevention control (first control) by the sheet float prevention device according to one embodiment of the present invention are shown. It is a figure shown according to the rotation angle of an impression cylinder. The operation non-operation states of the first sheet pressing device and the second sheet pressing device according to the floating prevention control (first control) by the sheet floating prevention device according to the embodiment of the present invention are illustrated in FIGS. FIG. It is an air supply system figure explaining the action | operation of the sheet | seat floating prevention apparatus concerning the modification of one Embodiment of this invention. It is a block diagram which shows the floating prevention apparatus of the sheet | seat concerning background art with the principal part cross section of a double-sided printing machine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIGS. 1-6 demonstrates one Embodiment of this invention, and it demonstrates based on these figures. In the following embodiment, a double-sided offset sheet-fed printing press will be described as an example. However, the present invention can also be applied to a single-sided offset sheet-fed printing press (so-called single-sided printing machine).

[Configuration of the printing press]
As shown in FIG. 2, a sheet-fed printing machine according to the present embodiment is a double-sided offset sheet-fed printing machine (hereinafter simply referred to as a sheet-fed printing machine) 1 and is a normal paper such as art paper or coated paper. In addition, a sheet F represented by a film or the like (a sheet-like printing sheet such as a sheet, hereinafter also simply referred to as a printing sheet) S is printed as a printing medium.

The sheet-fed printing press 1 includes a paper feeding unit 2, a back surface printing unit 3 and a front surface printing unit 4 as a printing unit, and a paper discharge unit 5 from the upstream side in the direction in which the printing sheet S is conveyed. The back surface printing unit 3 and the front surface printing unit 4 are connected by a connecting unit 6. The back surface printing unit 3 and the front surface printing unit 4 have a plurality of printing units 7 and 8, respectively.
In this embodiment, a double-sided machine that prints the front side after printing the back side will be described. However, it is a reversing machine that reverses the front and back of the paper in the middle, or a two-storied double-sided machine with an impression cylinder-impression cylinder replacement method. Is also applicable to the present invention.

  The paper feed unit 2 includes a paper feed tray 13 and a paper feed mechanism 14. The sheet feed table 13 is for stacking and placing sheets S, and the sheet feed mechanism 14 is for picking up and supplying the sheets S stacked on the sheet feed table 13 one by one from the top. Yes, composed of separator (paper suction), cam, feeding roller, etc. The paper feed tray 13 is controlled to move upward in the vertical direction corresponding to the supply of the print sheet S so that the paper feed mechanism 14 maintains a substantially constant positional relationship with the print sheet S.

  The back surface printing unit 3 and the front surface printing unit 4 include a plurality of printing units 7 and 8 that perform color printing by printing a plurality of different color inks. A plurality of printing units 7 and 8 are provided side by side along the advancing direction L of the printing sheet S for each color to be printed. In the sheet-fed printing press 1, the back surface printing unit 3 and the front surface printing unit 4 respectively For example, four printing units 7 and 8 corresponding to four different ink colors such as C (cyan), M (magenta), Y (yellow), and K (black) are provided. The type of ink color is not limited to this, and the number of printing units is not limited to this.

  Each printing unit 7, 8 includes a plate cylinder 15, a rubber cylinder (blanket cylinder) 16, and an impression cylinder 17. The plate cylinder 15, the rubber cylinder 16 and the impression cylinder 17 are arranged so as to contact each other in this order from the lower side to the upper side in the apparatus in the back surface printing unit 3 and from the upper side to the lower side in the apparatus in the front surface printing unit 4. Has been. The plate cylinder 15, the rubber cylinder 16, and the impression cylinder 17 are each formed in a cylindrical shape and provided so that the center axis thereof intersects the traveling direction L horizontally. The plate cylinder 15, the rubber cylinder 16, and the impression cylinder 17 are provided so as to be rotatable around the central axis.

  The plate cylinder 15 is mounted with a printing plate for forming a printed image on the peripheral surface. Each of the printing units 7 and 8 has an ink supply device (not shown) composed of a roller group for supplying ink to the image line portion of the printing plate and dampening water to the non-image area around the plate cylinder 15. A dampening device (not shown) including a water roller group for supply is provided. The rubber cylinder 16 is provided with rubber formed of an elastic material on the peripheral surface, and the ink supplied to the image line portion of the plate cylinder 15 is transferred to the rubber, and the printed image is transferred to the sheet S as a picture. The impression cylinder 17 applies a predetermined printing pressure in cooperation with the rubber cylinder 16.

  The impression cylinder 17 is a so-called double cylinder having a diameter twice as large as that of the plate cylinder 15 and the rubber cylinder 16, and a claw device (not shown) is provided on the peripheral surface to bite and hold the leading end of the printing sheet S. . The claw device is provided at two locations almost symmetrically across the central axis of the impression cylinder 17. In addition, although the structure which uses a double cylinder was employ | adopted in this embodiment, it is not restricted to this, The impression cylinder of the single cylinder type (a nail | claw apparatus will be provided in one place) with the same diameter as a plate cylinder is used. It may be used.

  Each printing unit 7, 8 further includes an intermediate cylinder 18. The intermediate cylinder 18 is arranged on the upstream side of the impression cylinder 17 with respect to the traveling direction L of the printing sheet S so as to be in contact with the impression cylinder 17. Similar to the plate cylinder 15, the rubber cylinder 16, and the impression cylinder 17, the intermediate cylinder 18 is formed in a cylindrical shape and is provided so that its center axis intersects the traveling direction L horizontally, and the center axis is the center of rotation. It is provided rotatably.

  Similarly to the impression cylinder 17, the intermediate cylinder 18 is a so-called double cylinder having a diameter twice the diameter of the plate cylinder 15 and the rubber cylinder 16, and bites the leading edge of the sheet S at two locations on the peripheral surface. A holding claw device (not shown) is provided. In addition, although the structure which uses a double cylinder was employ | adopted in this embodiment, it is not restricted to this, The intermediate | middle cylinder of the single cylinder type (a nail | claw apparatus will be provided in one place) with the same diameter as a plate cylinder is used. It may be used.

  The printing units 7 and 8 are arranged such that the intermediate cylinders 18 are in contact with the impression cylinders 17 of the printing units 7 adjacent to the upstream side in the traveling direction L of the sheet S. The printing sheet S supplied from the paper feeding unit 2 is first supplied between the rubber cylinder 16 and the impression cylinder 17 of the printing unit 7 positioned on the most upstream side in the back surface printing unit 3, and then printed on the downstream side. By changing the nail device from the intermediate cylinder 18 to the impression cylinder 17 of the units 7 and 8, they are conveyed through the printing units 7 and 8, and ink is transferred one after another on the way.

  The paper discharge unit 5 transports and stacks the print sheets S printed on both sides by the back surface printing unit 3 and the front surface printing unit 4 in an aligned state. The paper discharge unit 5 includes a conveyance unit 19 that conveys the printed print sheet S, a paper discharge table 20 on which the print sheets S are stacked, a fan device 21 that forms a downward airflow in the vicinity of the paper discharge table 20, A vacuum suction wheel device 22, a paper pad 23, a rear paper aligning device 24, and a width direction paper aligning device 25 are provided.

  With such a configuration, in the sheet-fed printing press 1, when the printing sheet S is supplied from the paper feeding unit 2 to the back surface printing unit 3, first, the printing sheet S serving as a printing surface is printed by the plurality of printing units 7. A printed image is transferred for each of the four colors of ink on the back surface of the ink. After that, it is conveyed to the surface printing unit 4 by the connecting unit 6. Then, in the same manner as the printing process in the back surface printing unit 3 described above, the front surface of the print sheet S printed on the back surface is used as a printing surface, and a plurality of printing units 8 of the back surface printing unit 3 are used to print four colors. After the ink has been transferred in sequence, the paper discharge unit 5 transports and discharges the ink by the transport unit 19, and the fan device 21, vacuum suction wheel device 22, paper pad 23, rear paper alignment device 24, and width direction paper alignment device 25. They are aligned and stacked on the paper discharge tray 20. That is, in this double-sided offset sheet-fed printing press 1, after printing on the back surface of the printing sheet S, it is possible to print on the surface of the printing sheet S without inverting the printing sheet S.

  Depending on the print order, printing may be performed using only a part of a plurality of (in this case, four) printing units 7 and 8. In this case, in a printing unit that is not used, “barrel removal” for separating the rubber cylinder 16 from the impression cylinder 17 is performed. Of course, the printing unit to be used performs “cylinder insertion” in which the rubber cylinder 16 is pressed against the impression cylinder 17. At the time of the cylinder insertion, the printing sheet S is transferred with ink from the rubber cylinder 16 while being held in the nip portion between the rubber cylinder 16 and the impression cylinder 17.

  This sheet-fed printing machine 1 includes a downstream printing unit 3 and a front printing unit 4 in the final printing unit of each of the final printing units, the rubber cylinder (final rubber cylinder) 16E and the impression cylinder (final impression cylinder) 17E immediately downstream of the nip NP. Is provided as an accessory device with a photographing device (camera) 30 for photographing the printing surface of the printing sheet S conveyed along the outer peripheral surface of the impression cylinder 17E. It is used for management. In FIG. 2, the installation location of the camera 30 is indicated by a star C.

The camera 30 can be an electronic camera such as a CCD camera that can record and convert a captured image into an electrical signal using an image sensor such as a CCD, or a line sensor configured by arranging image sensors on a line. In addition, a density sensor that detects the color density of the color by an image sensor may be applied, and the type of camera is not limited.
In addition, here, a case where the final printing unit is equipped with the camera 30 will be described, but the camera 30 may be provided in the intermediate printing unit.

[Configuration near the camera of the final printing unit]
FIG. 1 shows a nip portion NP between the final rubber cylinder 16E and the final impression cylinder 17E of the final printing unit of the front surface printing unit 4 and its downstream in a schematic cross section, and also shows the camera 30 and the present apparatus (preventing sheet sheet float). Device). In the case of the final printing unit of the back surface printing unit 3, the final rubber cylinder 16E, the final impression cylinder 17E, and the camera 30 are different from those shown in FIG. Since the configuration is substantially the same as that of the surface printing unit 4, the illustration is omitted.

  As shown in FIG. 1, downstream of the nip NP between the final rubber cylinder 16E and the final impression cylinder 17E, the camera 30 includes a specific portion of the outer peripheral surface of the final impression cylinder 17E in the imaging target area of the image detection unit 30a. Equipped for an area (specific area). Here, the camera 30 is disposed close to the nip portion NP, and the image detection unit 30a shoots the center of the photographic object for image detection toward a specific location.

  The specific portion mentioned here is a portion close to the nip portion NP downstream of the nip portion NP, and the circumferential length along the outer peripheral surface of the impression cylinder 17E from the nip portion NP to the specific portion is the conveyance of the printing sheet S. Accordingly, at least when the front end of the print sheet S enters the specific portion, the rear end of the print sheet S is positioned upstream of the nip portion NP in the transport direction. ing.

In addition, here, the center of the imaging target of the image detection unit 30a of the camera 30 is directed to a specific location so that the later-described prevention of floating of a sheet can be efficiently performed. It suffices if the location is included, and it is not always necessary to direct the center of the imaging target to a specific location.
In the vicinity of the camera 30, a first sheet pressing device 31 and a second sheet pressing device 32 are provided.

  The first sheet pressing device 31 is disposed upstream of the camera 30 (upstream in the direction in which the print sheet S is transferred) and adjacent to the camera 30 between the nip portion NP and the camera 30, and is located in the photographing region 30A. In the vicinity, the printing sheet S is pressed against the outer circumferential surface of the impression cylinder 17E to restrain the printing sheet S from floating from the outer circumferential surface of the impression cylinder 17E in the photographing region 30A (upstream sheet pressing process).

  In the present embodiment, the first sheet pressing device 31 is an air type device (hereinafter also referred to as a first air shower) that presses the printed sheet S against the outer peripheral surface of the impression cylinder 17E by air injection. In the first sheet pressing device 31, air is injected at an angle close to a right angle to the outer peripheral surface of the impression cylinder 17E (for example, a right angle of about ± 30 °). As the first sheet pressing device 31, a contact-type device such as a roller-type device in which a roller is brought into contact with the print sheet S and the print sheet S is pressed against the outer peripheral surface of the impression cylinder 17E can be applied. In the case of the contact type, a configuration in which a pressing member such as a roller is brought into contact with a non-printing portion (for example, both edges in the width direction or the middle portion in the width direction) of the printing surface of the printing sheet S. It can be.

  The second sheet pressing device 32 is an air type device (hereinafter also referred to as a second air shower), and is disposed downstream of the camera 30 (downstream in the direction in which the print sheet S is transferred) and upstream in the transfer direction. The print sheet S is pressed against the outer peripheral surface of the impression cylinder 17E in the vicinity of the imaging region 30A by injecting air toward the imaging region 30A, and is constrained so that the print sheet S does not float from the outer peripheral surface of the impression cylinder 17E in the imaging region 30A ( Downstream sheet presser process). The second sheet pressing device 32 injects air at a shallow angle (for example, about 0 ° (tangential) to 45 °) near the tangent to the outer peripheral surface of the impression cylinder 17E in the vicinity of the imaging region 30A. Thus, when air is injected at a shallow angle with respect to the printing sheet S along the outer peripheral surface of the impression cylinder 17E from the downstream side in the conveyance direction of the printing sheet S, the air turbulence component is suppressed while suppressing the lifting of the printing sheet S. In particular, it is easy to suppress the flutter on the rear end side of the print sheet S, which is likely to occur when the print sheet S is a low-rigidity sheet such as thin paper.

Further, the outer shape of the case of the photographing device 30 is on the inclined surface 30b side (downstream in the conveying direction) because the downstream surface in the conveying direction is an inclined surface 30b that is inclined so as to be away from the impression cylinder 17E. The air blown from the air nozzle of the second sheet pressing device 32 easily flows into the imaging region 30A from between the inclined surface 30b and the impression cylinder 17E along the inclined surface 30b.
An air blow (air supply source) 41 is connected to the first air shower 31 as the first sheet pressing device and the second air shower 32 as the second sheet pressing device via an air pipe and a rotary valve 42. Yes.

  The rotary valve 42 includes an inlet port 42 </ b> C connected to an air blow (air supply source) 41, a first outlet port 42 </ b> A connected to the first air shower 31, and a second outlet port connected to the second air shower 32. 42B. The rotary valve 42 has a first valve portion 42a and a second valve portion 42b that open and close the first outlet port 42A and the second outlet port 42B, respectively, according to the rotational phase.

Therefore, if the rotation phase of the rotary valve 42 is adjusted, the first outlet port 42A and the second outlet port 42B can be controlled to open and close.
The rotary valve 42 is electronically controlled by an electronic control device (ECU: electronic control unit, control device) 50.
The ECU 50 provides information on whether the rubber cylinder 16E is in a cylinder-insertion state or a cylinder-extraction state, and whether the rigidity of the print sheet S is a low-rigidity sheet (thin paper) having a rigidity equal to or lower than the reference rigidity, or higher than the second reference rigidity. Information on whether the sheet is a high-rigidity sheet (thick paper) and information on the rotation angle θ of the impression cylinder 17E are input. Based on these information, the rotation phase of the rotary valve 42 is controlled and air blow 41 is controlled.

Although omitted in FIG. 1, in this embodiment, as shown in FIG. 3, two air blows 41A and 41B are further provided and connected to the first air shower 31 via an air pipe. The ECU 50 also controls the operation of the air blows 41A and 41B based on the above information.
The air pipe at the outlet of the air blow 41 is provided with an air volume adjusting valve 43, and the air pipes at the outlet of the air blows 41A and 41B are provided with air volume adjusting valves 46a and 46b, respectively. Check valves 47, 47a, 47b are provided immediately downstream of 46b to prevent backflow of air to the air blows 41, 41A, 41B.

The air volume adjustment of the air blows 41, 41A, 41B is not limited to the air volume adjustment valves 43, 46a, 46b. For example, output control by an inverter may be applied to the air volume adjustment of the air blow.
Pressure switches 44 and 45 are provided in the air piping near the entrances of the first air shower 31 and the second air shower 32, and the first sheet pressing device 31 and the second sheet pressing device are provided by the pressure switches 44 and 45. 32 is confirmed and fed back to the ECU 50.

[Air supply control]
Here, air supply control by the ECU 50 will be described.
In the ECU 50, basically, the rigidity of the print sheet S, that is, whether the print sheet S is a low-rigidity sheet (thin paper) or a high-rigidity sheet (thick paper), whether the rubber cylinder 16E is in a cylinder-inserted state or a cylinder-extracted state. Different air supply modes are implemented with combinations of the two system conditions. In this embodiment, a medium rigid sheet (medium thick paper) is divided between a low rigid sheet (thin paper) having a reference rigidity (first reference rigidity) or less and a high rigidity sheet (thick paper) having a second reference rigidity higher than that. And a unique air supply mode is also provided for the medium-rigid sheet.

  Such a division between thin paper and thick paper, or a division between thin paper, medium thick paper and thick paper is performed by comparing the rigidity of the paper with the reference rigidity, or the first reference rigidity and the second reference rigidity. Such classification can be performed by paying attention to the basis weight that correlates with the rigidity of the paper. For example, in the case of two categories of thin paper and thick paper, a reference basis weight corresponding to the reference rigidity is set, a paper having a basis weight equal to or less than the reference basis weight is set to a thin paper (low rigidity sheet), and a basis weight larger than the reference basis weight is set. The paper can be a thick paper (high rigidity sheet).

Further, in the case of three categories of thin paper, medium thick paper, and thick paper, a first reference basis weight corresponding to the first reference rigidity and a second reference basis weight corresponding to a second reference rigidity larger than the first reference basis weight are obtained. Set the paper with the basis weight below the first reference basis weight to be thin paper (low-rigidity sheet), and the paper with the basis weight larger than the first reference basis weight and below the second reference basis weight to medium-thick paper (medium-rigid sheet) And a paper having a basis weight larger than the second reference basis weight can be used as a cardboard (high rigidity sheet).
Hereinafter, each air supply mode will be sequentially described.

(Thin paper cylinder insertion mode, second control)
When the print sheet S is a low-rigidity sheet (thin paper) and the rubber cylinder 16E is in a cylinder-inserted state, the ECU 50 stops all the air blows 41, 41A, 41B. When the printing sheet S is a low-rigidity sheet (thin paper), if the rubber cylinder 16E is in a cylinder-inserted state, the printing sheet S is between the rubber cylinder 16E and the impression cylinder 17E while passing through the nip portion NP. Therefore, even if both the first air shower 31 and the second air shower 32 are deactivated, it is possible to prevent the printing sheet S from lifting up from the outer peripheral surface of the impression cylinder 17E without any trouble. Unnecessary operations of 31 and 32 can be prevented.

(Thin paper drum removal mode, first control)
When the print sheet S is a low-rigidity sheet (thin paper) and the rubber cylinder 16E is in the cylinder-extracted state, the ECU 50 causes the intermediate portion Sm from the front end Sf of the print sheet S to pass through the imaging region 30A of the camera 30. During this time, the first air shower 31 is activated and the second air shower 32 is deactivated. Thereafter, while the rear end Sr from the intermediate portion Sm of the print sheet S passes through the imaging region 30A, the second air shower is activated. 32 is activated and the first air shower 31 is deactivated.

The ECU 50 operates and stops the operation of the first air shower 31 and the second air shower 32 at this time by controlling the rotation phase of the rotary valve 42 based on the information of the rotation angle θ of the impression cylinder 17E.
As shown in FIG. 4, the rotary valve 42 controls air supply to the first outlet port 42A and the second outlet port 42B in accordance with the rotational phase of the valve body. In FIG. 4, the reference phase is indicated by a one-dot chain line and a triangular mark so that the rotational phases of the first valve portion 42 a and the second valve portion 42 b of the rotary valve 42 at each port 42 </ b> A, 42 </ b> B can be seen.

  That is, in the rotational phase state shown in FIG. 4 (a), both the first outlet port 42A and the second outlet port 42B have an opening degree of 50%, and the rotary valve 42 rotates slightly from here to FIG. 4 (b). In the rotational phase state shown, the first outlet port 42A is closed and the second outlet port 42B is opened (opening degree: 100%). Further, when the rotary valve 42 rotates and passes through the rotational phase state shown in FIG. 4 (c) and reaches the rotational phase state shown in FIG. 4 (d), the first outlet port 42A opens (opening degree of 100%). The second outlet port 42B is closed.

  Therefore, while the intermediate portion Sm from the front end portion Sf of the print sheet S passes through the imaging region 30A of the camera 30, the ECU 50 sets the rotary valve 42 to the rotational phase state shown in FIG. The outlet port 42A is opened (the opening degree is 100%), the second outlet port 42B is closed, and the first air shower 31 is turned on as shown in FIGS. 5 (a), 5 (b) and 6 (a), The second air shower 32 is turned off.

Thereby, the floating from the outer peripheral surface of the impression cylinder 17E of the intermediate part Sm from the front end part Sf of the printing sheet S is prevented.
Thereafter, while the rear end Sr from the intermediate portion Sm of the print sheet S passes through the imaging region 30A, the ECU 50 places the rotary valve 42 in the rotational phase state shown in FIG. The first outlet port 42A is closed, the second outlet port 42B is opened (opening degree 100%), and the second air shower 32 is turned on as shown in FIGS. 5 (a), 5 (b) and 6 (c). The first air shower 31 is turned off.

Accordingly, the printing sheet S is prevented from being lifted from the outer peripheral surface of the impression cylinder 17E without fluttering the rear end portion Sr from the intermediate portion Sm of the printing sheet S.
At the time of this switching, as shown in FIGS. 4A and 6B, an intermediate state in which both the first air shower 31 and the second air shower 32 operate is interposed, and the valve opening degree is 50%. However, the air is also 50%, but both may be off (opening degree 0%).

(Cardboard case mode, 4th control)
When the printing sheet S is a high-rigidity sheet (thick paper) and the rubber cylinder 16E is in the cylinder-inserted state, the ECU 50 operates only the air blow 41 and turns the rotary valve 42 to the rotational phase shown in FIG. In the state, the first outlet port 42A is opened (the opening degree is 100%), the second outlet port 42B is closed, and the first outlet port 42A is closed as shown in FIGS. 5 (a), 5 (b) and 6 (a). The air shower 31 is turned on and the second air shower 32 is turned off.

  In the case of a high-rigidity sheet, when the rubber cylinder 16E is in a cylinder-inserted state, the printing sheet S is sandwiched between the rubber cylinder 16E and the impression cylinder 17E while passing through the nip portion NP. Since the first air shower 31 is activated and the second air shower 32 is deactivated, the air sheet is prevented from being lifted from the outer peripheral surface of the impression cylinder 17E while suppressing excessive operation of the air shower. can do. In the case of a highly rigid sheet, even if air is jetted toward the surface of the print sheet S, the print sheet S does not flutter due to its own rigidity. Further, by stopping the operation of the second sheet pressing device, it is possible to reduce the drying of the surface of the rubber cylinder 16 due to the air toward the rubber cylinder 16 side.

(Cardboard unrolling mode, third control)
When the printing sheet S is a high-rigidity sheet (thick paper) and the rubber cylinder 16E is in the cylinder-extracted state, the ECU 50 operates all of the air blows 41, 41A, and 41B to change the rotary valve 42 as shown in FIG. In the rotational phase state shown in b) or (c), the first outlet port 42A is closed, the second outlet port 42B is opened (opening degree 100%), and as shown in FIG. The air shower 32 is turned on and the first air shower 31 is turned on.

The air flow adjustment valves 43, 46a, and 46b of the air blows 41, 41A, and 41B are fully opened, the maximum air flow from the air blow 41 from the second air shower 32, and the air blows 41A and 41B from the first air shower 31. The maximum flow of air from is injected.
Air blows 41, 41 </ b> A, 41 </ b> B are of the same standard, and air having a flow rate approximately twice that of the second air shower 32 is ejected from the first air shower 31.
In the case of a highly rigid sheet (thick paper), when the rubber cylinder 16E is in the cylinder-extracted state, the print sheet S is likely to float from the outer peripheral surface of the impression cylinder 17E due to its own rigidity, but the first air shower 31 and the second air shower. By operating 32 at the maximum flow rate, it is possible to increase the amount of air injection and press the printed sheet S against the outer peripheral surface of the impression cylinder 17E, and to lift the printed sheet S from the outer peripheral surface of the impression cylinder 17E. Can be prevented.

(Medium cardboard mode)
When the printing sheet S is a medium-rigid sheet (medium-thick paper) and placed in a cylinder, intermediate control between a low-rigidity sheet (thin paper) and a high-rigidity sheet (thick paper) is performed. That is, even when the cylinder is inserted, like the high-rigidity sheet (thick paper), only the air blow 41 is operated to turn on the first air shower 31 and turn off the second air shower 32. (Reference numeral 43 '), the air flow rate is suppressed, and the middle rigid sheet (medium thick paper) is prevented from fluttering while being prevented from lifting from the outer peripheral surface of the impression cylinder 17E.

(Medium cardboard unrolling mode)
When the printing sheet S is a medium-rigid sheet (medium-thick paper) and is unrolled, intermediate control between a low-rigidity sheet (thin paper) and a high-rigidity sheet (thick paper) is performed. That is, only one of the air blow 41 and the air blows 41A and 41B is operated, the first air shower 31 is turned on, the second air shower 32 is turned on, the air volume adjustment valve 43 is throttled, the air flow rate is suppressed, While preventing the fluttering of the rigid sheet (medium thick paper), the lifting from the outer peripheral surface of the impression cylinder 17E is prevented. It is also possible to suppress the flow rate of air while suppressing the output of the air blows 41, 41A, 41B and turning on all of the air blows 41, 41A, 41B.

(Action, effect)
According to the sheet prevention apparatus or the prevention method of the sheet-fed sheet of the present invention, the fluttering of the printing sheet S is suppressed according to the rigidity (paper thickness) of the printing sheet S, the cylinder removal of the rubber cylinder 16E, and the cylinder insertion. Lifting from the outer peripheral surface of the impression cylinder 17E can be prevented.
In order to improve the print quality control accuracy, a high-quality captured image by the camera 30 is required, and it is effective to bring the camera 30 closer to the photographing region 30A. However, the closer the camera 30 is to the photographing region 30A. A slight lift or fluttering of the print sheet S causes a significant shift from the focus of the image detection unit 30a of the camera 30 and lowers the image quality and reduces the print quality control accuracy. However, such a problem is also avoided. .

[Others]
As mentioned above, although embodiment of this invention was described, this invention can be implemented by changing this embodiment suitably.
For example, in the above embodiment, the rigidity of the sheet is divided into three stages of a low-rigidity sheet (thin paper), a medium-rigid sheet (medium-thick paper), and a rigid sheet (thick paper). It may be divided into two stages of rigid sheets (thick paper) or more than three stages.

Further, if considered to be dedicated to low-rigidity sheets (thin paper), the air blowers 41A and 41B and the supply system attached thereto are omitted as shown in FIG. May be performed.
Further, the accessory device is not limited to the camera, and may be a UV-type drying device that irradiates the printing surface of the sheet by ultraviolet rays in order to dry the UV ink transferred to the printing surface. In this case, the ultraviolet irradiation target region (ultraviolet irradiation region) of the UV drying apparatus may include a specific portion, and each part of the apparatus may be arranged with the ultraviolet irradiation region as the specific region. Also in this case, if the ultraviolet irradiation center of the UV-type drying apparatus is directed to a specific location, an ultraviolet irradiation region (specific region) is formed around the specific location, and the sheet can be efficiently prevented from being lifted. Of course, it is sufficient that the ultraviolet irradiation region includes a specific portion, and the ultraviolet irradiation center does not necessarily have to be directed to the specific portion.

1 sheet-fed printing machine (double-sided printing machine)
2 Paper feeding unit 3 Back side printing unit (printing unit)
4 Front side printing section (printing section)
DESCRIPTION OF SYMBOLS 5 Paper discharge part 6 Connection unit 7,8 Printing unit 13 Paper feed stand 14 Paper feed mechanism 15 Plate cylinder 16 Blanket cylinder 17 Impression cylinder 18 Intermediate | middle drum 19 Conveyance part 20 Paper discharge stand 30 Imaging device (camera)
30a Image detection unit 30b Inclined surface of the photographing device 30 31 First sheet pressing device (first air shower)
32 Second sheet presser (second air shower)
41 Air blow (Air supply source)
42 Rotary valve 50 Electronic control unit (ECU: Electronic control unit, control unit)
S printing sheet

Claims (11)

While holding the front end, the sheet sheet fed from the nip between the impression cylinder and the rubber cylinder of the sheet-fed printing press and transferred along the outer circumferential surface of the impression cylinder is the outer circumferential surface of the impression cylinder at a specific location. A device for preventing the sheet from floating from being lifted from
A first sheet pressing device that is disposed downstream of the nip portion in the transfer direction and presses the sheet to the outer peripheral surface of the impression cylinder in a specific area including the specific location;
An air type first device that is disposed downstream of the first sheet pressing device in the transport direction and injects air toward the upstream in the transport direction to press the single sheet against the outer peripheral surface of the impression cylinder in the specific region. A two-sheet presser;
A control device for controlling the operation of the first sheet pressing device and the second sheet pressing device;
The control device operates the first sheet presser device and the second sheet presser while the intermediate portion passes from the front end portion of the sheet to the specific region when the rubber cylinder is in the unrolled state. A first control for operating the second sheet pressing device and stopping the first sheet pressing device while the operation of the device is stopped and the rear end of the sheet passes through the specific region. A device for preventing the sheet from floating. The controller is
The first control is performed when the rubber cylinder is in a barrel-removed state on the condition that the rigidity of the single-wafer sheet is a low-rigidity sheet having a standard rigidity or less. 2. The sheet-float prevention device according to claim 1, wherein second control is performed to stop operation of both the first sheet pressing device and the second sheet pressing device. The controller is
Both the first sheet pressing device and the second sheet pressing device are operated when the rubber cylinder is in the unrolled state on condition that the sheet is a high-rigidity sheet whose rigidity is higher than the standard rigidity. 3. The third sheet control according to claim 1, wherein the third control is performed. The controller is
On the condition that the rigidity of the sheet is a high-rigidity sheet that is higher than the standard rigidity, the first sheet pressing device is operated and the second sheet pressing device is operated when the rubber cylinder is in a retracted state. The apparatus for preventing floating of a sheet according to any one of claims 1 to 3, wherein the fourth control for stopping the operation is performed. The first sheet pressing device is configured as an air-type sheet pressing device that presses the sheet to the outer peripheral surface of the impression cylinder by injecting air toward the surface of the sheet.
A rotary valve that switches a supply state of air to the air type first sheet pressing device and the air type second sheet pressing device;
The said control apparatus controls the action | operation of the said 1st sheet pressing apparatus and the said 2nd sheet pressing apparatus by controlling the rotation phase of the said rotary valve, The any one of Claims 1-4 characterized by the above-mentioned. The sheet | seat prevention apparatus of sheet | seat as described in an item. The sheet according to any one of claims 1 to 5, wherein the air injection amount of the second sheet pressing device is set to be smaller than the air injection amount of the first sheet pressing device. Leaf sheet float prevention device. Opposite to the impression cylinder of a sheet-fed printing machine that performs printing on the printing surface of the sheet, a photographing device for photographing the printing surface of the sheet is provided for print quality control. The sheet float prevention device according to any one of claims 1 to 6, wherein Irradiating ultraviolet rays to the printing surface of the sheet for drying the UV ink transferred to the printing surface facing the impression cylinder of the sheet-fed printing press that performs printing on the printing surface of the sheet. The sheet-type sheet floating prevention device according to any one of claims 1 to 6, wherein a UV-type drying device is provided. An impression cylinder that bites the front end of the sheet and rotates the sheet while holding the sheet along the outer peripheral surface to transfer the sheet;
Sheet-fed printing having a rubber cylinder that can be switched between a cylinder-inserted state in which a nip is engaged with the impression cylinder and ink can be transferred to the printing surface of the sheet-fed sheet, and a cylinder-extracted state that is separated from the impression cylinder Machine,
The sheet-fed sheet float prevention according to any one of claims 1 to 8, on the outer periphery of the impression cylinder downstream of a nip portion where the rubber cylinder is nip-engaged with the impression cylinder in the cylinder insertion state. A sheet-fed printing press, characterized in that it is equipped with a device. A sheet sheet fed out from the nip between the impression cylinder and the rubber cylinder of the sheet-fed printing press while being held at the front end portion and transferred along the outer peripheral surface of the impression cylinder from the outer peripheral surface of the impression cylinder at a specific location. A method for preventing the sheet from floating to prevent the sheet from floating,
While the rubber cylinder is unrolled, the intermediate portion passes from the front end portion of the sheet to the specific region including the specific location, and the nip portion and the specific location upstream of the specific location in the transfer direction. Pressing the sheet to the outer peripheral surface of the impression cylinder, and performing an upstream sheet pressing process,
While the rear end portion from the intermediate portion of the single sheet passes through the specific region, the single sheet is pressed against the outer peripheral surface of the impression cylinder using air downstream in the transfer direction from the specific portion. A method for preventing a sheet from floating, wherein a downstream sheet pressing process is performed. Under the condition that the rigidity of the single sheet is a high rigidity sheet higher than the standard rigidity, at the time of unrolling the rubber cylinder, at least while the rear end part from the front end part of the single sheet passes through the specific region. The method of preventing sheet sheet floating according to claim 10, wherein the upstream sheet pressing process and the downstream sheet pressing process are performed.

Images