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The present invention relates to a printing cylinder structure for various types of rotary presses, such as a web offset press or offset rotary press, each having a printing section equipped with a blanket cylinder, a plate cylinder, a group of ink rolls for transferring printing ink onto the plate cylinder, etc.
BACKGROUND ART
A printing cylinder structure for a conventional rotary press is designed to apply a certain printing pressure between a plate cylinder and a blanket cylinder so as to allow printing ink on a printing surface of a press plate wound on an outer peripheral surface of the plate cylinder to be reliably transferred onto an outer peripheral surface of a blanket wound on an outer peripheral surface of the blanket cylinder.
As shown in FIG. 10, each of the plate cylinder and the blanket cylinder has an outer peripheral surface formed with a gap (groove) for engagingly locking opposite ends of a corresponding one of the press plate and the blanket. The gaps la, 2a are formed to be periodically located in opposed relation to each other at the same position along with rotations of the plate and blanket cylinders during printing. Thus, in conjunction with overlapping of the gaps la, 2a each extending over the entire cylinder width, a situation where no pressing pressure is applied between the plate and blanket cylinders will periodically occur to generate vibration in paper web, causing a shock mark or the like. Moreover, when the gaps are located in opposed relation to the web surface, a tension (tensile force) to be applied to a surface of the paper web is largely lowered to cause web slippage.
As measures for suppressing printing troubles due to the occurrence of web vibration and the lowering of web tension, for example in a printing cylinder structure using a plate cylinder having a four-page width (i.e., four-page-across plate cylinder), there has been known a technique of arranging two gaps each having a two-page width, respectively, at positions displaced relative to
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each other, as disclosed in the following Non-Patent Publication 1. Based on this technique, in a mainstream printing cylinder structure using a plate cylinder having a two-page circumferential length (i.e., two-page-around plate cylinder), the occurrence of web vibration and the lowering of web tension have been reduced to an acceptable level. However, it is getting harder for this technique to adequately meet a recent growing need for higher degree of printing accuracy.
The following Patent Publication 1 discloses a printing cylinder structure designed to divide a gap into four gaps or more in a cylinder-width direction, and arrange the divided gaps, respectively, at positions displaced relative to each other by given phase angles, so as to reduce the occurrence of web vibration and the lowering of web tension due to the gap.
In the printing cylinder structure disclosed in the Patent Publication 1, it is necessary to wind four blankets or more on a blanket cylinder. Thus, this printing cylinder structure involves a problem about complexity in an operation of attaching and detaching the blankets.
Patent Publication 1: Japanese Patent Laid-Open Publication No. 10-071694 Non-Patent Publication 1: Technical Committee of the Japan Newspaper Publishers & Editors Association, "Handbook of Newspaper Printing", 2nd impression of 1st edition, the Japan Newspaper Publishers & Editors Association, 03/31/1999, pp 58 to 59
DISCLOSURE OF THE INVENTION
In view of the above circumstances, it is an object of the present invention to provide a printing cylinder structure for a rotary press, capable of suppressing occurrence of web vibration and lowering of web tension due to a gap to prevent gap-related printing troubles, and free from complexity in an operation of attaching and detaching blankets.
In order to achieve the above object, the present invention provides a printing cylinder structure for a rotary press including a group of ink rolls, a plate cylinder having a press plate wound on an outer peripheral surface thereof and a blanket cylinder having a blanket wound on an outer peripheral surface thereof. The ink rolls are adapted to sequentially transfer printing ink between adjacent ones of the ink rolls while allowing the printing ink to be formed as an ink film in the course of the transfer. The press plate has a printing surface for transferably receiving the ink film from a last one of the ink rolls, and the blanket is adapted to allow the printing ink
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transferred on the printing surface of the press plate to be transferred onto a surface of a traveling web in a printing manner. This printing cylinder structure is characterized in that the blanket cylinder is designed to allow two of the blankets to be wound thereon in side-by-side relation to each other along an axial direction of the blanket cylinder. The outer peripheral surface of the blanket cylinder has two gaps formed therein and each adapted to engagingly lock opposite ends of a corresponding one of the blankets. One of the gaps is arranged at a position displaced relative to a position of the other gap in a circumferential direction of the blanket cylinder by a given phase angle. Further, the outer peripheral surface of the blanket cylinder or the blankets wound on the blanket cylinder have two raised portions formed thereon to extend along the axial direction of the blanket cylinder and lie on respective extension lines of the gaps.
In the above printing cylinder structure of the present invention, each of the raised portions may be formed to extend, or discontinuously extend, over the entire width of a corresponding one of the blankets at a position except for respective positions of the gaps. Each of the raised portions may be formed to have a width greater than that of a corresponding one of the gaps in the circumferential direction of the blanket cylinder. Each of the raised portions may be formed to have a curved shape in the circumferential direction of the blanket cylinder.
The present invention further provides a printing cylinder structure for a rotary press including a group of ink rolls, a plate cylinder having a press plate wound on an outer peripheral surface thereof and a blanket cylinder having a blanket wound on an outer peripheral surface thereof. The ink rolls are adapted to sequentially transfer printing ink between adjacent ones of the ink rolls while allowing the printing ink to be formed as an ink film in the course of the transfer. The press plate has a printing surface for transferably receiving the ink film from a last one of the ink rolls, and the blanket is adapted to allow the printing ink transferred on the printing surface of the press plate to be transferred onto a surface of a traveling web in a printing manner. This printing cylinder structure is characterized in that the blanket cylinder is designed to allow two of the blankets to be wound thereon in side-by-side relation to each other along an axial direction of the blanket cylinder. The outer peripheral surface of the blanket cylinder has two gaps formed therein and each adapted to engagingly lock opposite ends of a corresponding one of the blankets. One of the gaps is arranged at a position displaced relative to a position of the
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other gap in a circumferential direction of the blanket cylinder by a given phase angle. Further, the outer peripheral surface of the plate cylinder or the press plate wound on the plate cylinder has two raised portions formed thereon to extend along an axial direction of the plate cylinder and to be periodically located in opposed relation to respective extension lines of the gaps during printing.
In the above printing cylinder structure of the present invention, each of the raised portions may be formed to extend, or discontinuously extend, over the entire width of a portion of the outer peripheral surface of the plate cylinder or the press plate which is located in opposed relation to a corresponding one of the blankets at a position except for respective positions of the gaps. Each of the raised portions may be formed to have a width greater than that of a corresponding one of the gaps in the circumferential direction of the blanket cylinder. Each of the raised portions may be formed to have a curved shape in a circumferential direction of the plate cylinder.
The printing cylinder structure of the present invention has the following effects.
1. The raised portions formed to lie on respective extension lines of the gaps in the blanket
cylinder can prevent the plate cylinder from falling into the gaps. This makes it possible to
suppress occurrence of web vibration and lowering of web tension so as to prevent gap-related
printing troubles, such as a shock mark.
2. There is no need for dividing the blanket into an excessively large number of pieces.
This makes it possible to avoid complexity in an operation of attaching and detaching the
blankets.
3. Each of the raised portions may be formed to extend, or discontinuously extend, over the
entire width of a corresponding one of the blankets at a position except for respective positions of
the gaps, to further effectively prevent the plate cylinder from falling into the gaps.
4. Each of the raised portions may be formed to have a width greater than that of a
corresponding one of the gaps in the circumferential direction of the blanket cylinder, to further
effectively prevent the plate cylinder from falling into the gaps.
5. Each of the raised portions may be formed to have a curved shape in the circumferential
direction of the blanket cylinder, to reduce shock when the plate cylinder climbs over the
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respective raised portions so as to further effectively suppress the occurrence of web vibration and the lowering of web tension. The raised portions may be formed on the plate cylinder in the same manner as that in the blanket cylinder to obtain the same effects.
6. The raised portions may be formed on the blankets or the press plate to eliminate the need for modifying the blanket cylinder or plate cylinder, i.e., allow an existing blanket cylinder or plate cylinder to be used without any modification.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an explanatory diagram showing the configuration of a printing section of a rotary press using a printing cylinder structure of the present invention.
FIG. 2 shows a blanket cylinder according to one embodiment of the present invention, for use in the printing section of the rotary press illustrated in FIG. 1, wherein FIG 2(a) is a perspective view of the blanket cylinder, and FIGS. 2(b), 2(c) and 2(d) are, respectively, a sectional view taken along the line A-A in FIG 2(a), a sectional view taken along the line B-B in FIG. 2(b) and an enlarged sectional view taken along the line C-C in FIG. 2(a).
FIG. 3 is an enlarged sectional view showing another example of a raised portion formed on an outer peripheral surface of the blanket cylinder.
FIG. 4 is a schematic side view showing the blanket cylinder and a plate cylinder which are in rotational contact with each other.
FIG. 5 is a perspective view showing a blanket for use in a printing cylinder structure according to a second embodiment of the present invention.
FIG. 6 is a perspective view showing a blanket cylinder in a state after the blanket in FIG. 5 is wound thereon.
FIG. 7 is a schematic side view showing the blanket cylinder and a plate cylinder in the second embodiment, which are in rotational contact with each other.
FIG. 8 is a perspective view showing a press plate and a plate cylinder for use in a printing cylinder structure according to a third embodiment of the present invention.
FIG. 9 is a schematic side view showing the plate cylinder and a blanket cylinder in the third embodiment, which are in rotational contact with each other.
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FIG. 10 is a fragmentary sectional view showing a positional relationship between a gap formed in a plate cylinder and a gap formed in a blanket cylinder, during printing.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will now be described based on an embodiment thereof illustrated in the drawings.
[FIRST EMBODIMENT]
FIG. 1 is an explanatory diagram showing the configuration of a printing section of a rotary press using a printing cylinder structure of the present invention. The printing section of the rotary press illustrated in FIG 1 comprises two sets of right and left printing elements each of which includes a plate cylinder 1 having a press plate wound thereon, a blanket cylinder 2 having a rubber blanket wound thereon, an inking unit 3 and a dampening unit 4.
The inking unit 3 includes an ink pump 3a, and an ink roll group 3b consisting of a plurality of ink rolls. The ink pump is operable to supply printing ink to the ink roll group 3b. The ink roll group 3b is operable to sequentially transfer the supplied printing ink therethrough in the form of an ink film, and the last ink roll 3b-l in contact with the plate cylinder 1 is operable to transfer the ink film onto a printing surface of the press plate wound on an outer peripheral surface of the plate cylinder 1.
The dampening unit 4 includes a spiral brush-type dampening water feeder 4a, and two rolls operable to feed dampening water from the dampening water feeder 4a onto the printing surface of the press plate.
The printing section of the rotary press illustrated in FIG. 1 further comprises a monochromatic printing unit 5 which includes an ink reservoir 5a and a spot printing cylinder 5b. The monochromatic printing unit 5 is adapted to allow printing ink having a different color, such as red ink, fed from the ink reservoir 5a, to be supplied onto one of the blanket cylinders 2 through the spot printing cylinder 5b. The monochromatic printing unit 5 also includes a dampening water feeder 5c for feeding dampening water.
In each of the above printing elements, printing ink and dampening water are supplied, respectively, from the inking unit 3 and the dampening unit 4, onto the printing surface (not
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shown) of the press plate wound on the outer peripheral surface of the plate cylinder 1, and then the printing ink on the printing surface of the press plate is transferred onto the blanket cylinder 2. The printing ink on the two blanket cylinders 2 are simultaneously transferred, respectively, onto front and rear surfaces of a web W traveling between the blanket cylinders 2 in a printing manner.
FIG. 2 shows a blanket cylinder according to one embodiment of the present invention, for use in the printing section of the rotary press illustrated in FIG. 1, wherein FIG 2(a) is a perspective view of the blanket cylinder, and FIGS. 2(b), 2(c) and 2(d) are, respectively, a sectional view taken along the line A-A in FIG. 2(a), a sectional view taken along the line B-B in FIG. 2(b) and an enlarged sectional view taken along the line C-C in FIG 2
The blanket cylinder 2 illustrated in FIG. 2 is designed to allow two two-page-across blankets to be wound thereon in side-by-side relation to each other along an axial direction of the blanket cylinder 2. The blanket cylinder 2 has two gaps 2a, 2b formed in an outer peripheral surface thereof and each adapted to engagingly lock two aluminum fillet bars 7b (see FIG. 5) defining opposite ends of a corresponding one of the blankets, by means of frictional engagement or by use of a T-bar. One of the gaps, i.e., the gap 2a for engagingly locking the aluminum fillet bars 7b of one of the blankets, is arranged at a position displaced relative to a position of the other gap, i.e., the gap 2b for engagingly locking the aluminum fillet bars 7b of the other blanket, in a circumferential direction of the blanket cylinder 2 by a phase angle of 180-degree. Further, the outer peripheral surface of the blanket cylinder 2 has two raised portions 2c, 2d formed thereon to extend along the axial direction of the blanket cylinder 2 and lie on respective extension lines of the gaps 2a, 2b.
As shown in FIG. 2(d), each of the raised portions 2c, 2d is formed to have a smoothly curved shape along the circumferential direction of the blanket cylinder 2. In this embodiment, the raised portion is formed to have a height "t" of 0.03 mm, and a width "w" of 15 mm which is greater than a width (5 mm) of each of the gaps 2a, 2b in the circumferential direction of the blanket cylinder 2. Each of the raised portions 2c, 2d may be obtained by forming a build-up portion on the outer peripheral surface of the blanket cylinder 2 through deposit welding, and
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machining the build-up portion. Alternatively, as shown in FIG. 3, each of the raised portions 2c, 2d may be obtained by attaching a tape 6 onto the outer peripheral surface of the blanket cylinder 2, or by forming a build-up portion on the outer peripheral surface of the blanket cylinder 2 through plating, and machining the build-up portion.
FIG. 4 is a schematic side view showing the blanket cylinder and a plate cylinder which are in rotational contact with each other. The blanket cylinder 2 has two of the two-page-across blankets 7 wound thereon in side-by-side relation to each other along the axial direction thereof, and the plate cylinder 1 has two two-page-across press plates 8 wound thereon in side-by-side relation to each other along an axial direction thereof. The plate cylinder 1 has a single line of gap la formed in the outer peripheral surface thereof and adapted to engagingly lock leading and trailing edges of each of the press plates 8 by use of a spring or the like. The gap la is formed to be periodically located in opposed relation to the gap 2a or gap 2b at the same position during printing.
In FIG. 4, the plate cylinder 1 is a one-page-around type, and the blanket cylinder 2 is a two-page-around type.
As mentioned above, the blanket cylinder 2 has the raised portions 2c, 2d formed on the outer peripheral surface thereof to lie on respective extension lines of the gaps 2a, 2b. Thus, as shown in FIG. 4, even if the gap la of the plate cylinder 1 and the gap 2a of the blanket cylinder 2 are located in opposed relation to each other, the plate cylinder 1 will be rotated while climbing over the raised portion 2c of the blanket cylinder 2, so as to prevent the plate cylinder 1 from falling into the gap 2a and suppress lowering of web tension. This makes it possible to suppress the lowering of web tension and the occurrence of web vibration due to falling of the plate cylinder 1 into the gaps 2a, 2b of the blanket cylinder 2 so as to prevent gap-related printing troubles.
In addition, an operation of attaching and detaching the blankets can be performed in the same manner as that for the conventional printing cylinder structure using two blankets, without complexity.
In this embodiment, each of the raised portions 2c, 2d is formed to extend over the entire width of a corresponding one of the blankets at a position except for respective positions of the
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gaps 2a, 2b, as shown in FIG 2. Thus, the plate cylinder can climb over each of the raised portions 2c, 2d in its entirety while suppressing the occurrence of web vibration and the lowering of web tension. Further, each of the raised portions 2c, 2d is formed to have a smoothly curved shape along the circumferential direction of the blanket cylinder 2 and a width greater than that of each of the gaps 2a, 2b. Thus, the plate cylinder 1 can smoothly climb over each of the raised portions 2c, 2d.
[SECOND EMBODIMENT]
FIG 5 is a perspective view showing a blanket for use in a printing cylinder structure according to a second embodiment of the present invention. FIG. 6 is a perspective view showing a blanket cylinder in a state after the blanket in FIG 5 is wound thereon. In FIGS. 5 and 6, the same element or component as that in the first embodiment is defined by the same reference numeral, and its description will be omitted. In FIG 6, some components, such as a bearer, are omitted, as with FIG. 2.
While the raised portions in the first embodiment are formed on the blanket cylinder, a raised portion in the first embodiment is formed on a blanket. As with the first embodiment, a blanket cylinder 2 in the second embodiment is designed to allow two two-page-across blankets 7 to be wound thereon in side-by-side relation to each other along an axial direction of the blanket cylinder 2.
As shown in FIG 6, one of the blankets 7 is wound on the blanket cylinder 2 in such a manner that a raised portion 7a formed thereon lies on an extension line of a gap 2a of the blanket cylinder 2. The other blanket 7 is wound on the blanket cylinder 2 in such a manner that a raised portion 7a formed thereon lies on an extension line of a gap 2b of the blanket cylinder 2. Each of the raised portions 7a has the same shape as that of each of the raised portions 2c, 2d in the first embodiment.
FIG 7 is a schematic side view showing the blanket cylinder and a plate cylinder in the second embodiment, which are in rotational contact with each other. As shown in FIG 7, even if a gap la of the plate cylinder 1 and the gap 2a of the blanket cylinder 2 are located in opposed relation to each other, the plate cylinder 1 will be rotated while climbing over the raised portion 7a of the blanket 7, so as to prevent the plate cylinder 1 from falling into the gap 2a and suppress
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lowering of web tension. This makes it possible to suppress the lowering of web tension and the occurrence of web vibration due to falling of the plate cylinder 1 into the gaps 2a, 2b of the blanket cylinder 2 so as to prevent gap-related printing troubles, as with the first embodiment.
In addition, the raised portion 7a in the second embodiment is formed on the blanket 7. This makes it possible to eliminate the need for modifying the blanket cylinder 2, i.e., allow an existing blanket cylinder to be used without any modification.
[THIRD EMBODIMENT]
FIG. 8 is a perspective view showing a press plate and a plate cylinder for use in a printing cylinder structure according to a third embodiment of the present invention. In this embodiment, a raised portion is formed on the press plate 8. In FIG 8, the same element or component as that in the first embodiment is defined by the same reference numeral, and its description will be omitted. In FIG. 8, some components, such as a bearer at an end of the plate cylinder, are omitted for the sake of simplicity.
The plate cylinder 1 illustrated in FIG 8 is designed to allow two two-page-across and two-page-around press plates 8 to be wound thereon in side-by-side relation to each other along an axial direction there. The plate cylinder 1 has two gaps la, lb formed in an outer peripheral surface thereof and each adapted to engagingly lock leading and trailing edges of a corresponding one of the press plates 8 by use of a spring or the like. One of the gaps, i.e., the gap la for engagingly locking the leading and trailing edges of one of the press plates 8, is arranged at a position displaced relative to a position of the other gap, i.e., the gap lb for engagingly locking the leading and trailing edges of the other press plate 8, in a circumferential direction of the plate cylinder 1 by a phase angle of 180-degree. Each of the gaps la, lb is formed to be periodically located in opposed relation to a corresponding one of two gaps 2a, 2b of a blanket cylinder 2 during printing.
Each of the press plates 8 has a raised portion 8a formed thereon. One of the press plates 8 is wound on the plate cylinder 1 in such a manner that the raised portion 8a formed thereon lies on an extension line of the gap la of the plate cylinder 1. The other press plate 8 is wound on the plate cylinder 1 in such a manner that the raised portion 8a formed thereon lies on an extension line of the gap lb of the plate cylinder 1. Each of the raised portions 8a has the same shape as
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that of each of the raised portions 2c, 2d in the first embodiment.
FIG. 9 is a schematic side view showing the plate cylinder and a blanket cylinder in the third embodiment, which are in rotational contact with each other. As shown in FIG. 9, even if the gap la of the plate cylinder 1 and the gap 2a of the blanket cylinder 2 are located in opposed relation to each other, the plate cylinder 1 will be rotated while being moved away from the blanket cylinder 2 by the height of the raised portion 8a of the press plate 8, so as to prevent the plate cylinder 1 from falling into the gap 2a and suppress lowering of web tension. This makes it possible to suppress the lowering of web tension and the occurrence of web vibration due to falling of the plate cylinder 1 into the gaps 2a, 2b of the blanket cylinder 2 so as to prevent gap-related printing troubles.
In addition, the raised portion 8a in the second embodiment is formed on the press plate 8. This makes it possible to eliminate the need for modifying the plate cylinder 1, i.e., allow an existing plate cylinder to be used without any modification.
Although the embodiments of the present invention have been shown and described, the present invention is not limited to such specific embodiments. For example, while a one-page-around plate cylinder has been used in the first and second embodiments, a two-page-around plate cylinder may be used as in the blanket cylinder. In other words, as long as plate and blanket cylinders are designed such that a raised portion reliably lies at a position where respective gaps of the plate and blanket cylinders are located in opposed relation to each other, each of the plate and blanket cylinders is not limited to a specific length or diameter.
The height and width of the raised portion may be changed depending on printing conditions and/or a width of the gap. Further, as in the case where the raised portions are formed on the blanket cylinder, a plate cylinder may be formed with two raised portions each lying on an extension line of a corresponding one of two gaps formed therein at positions displaced relative to each other by a given phase angle, and two normal press plates may be wound on the plate cylinder.
The raised portion may be discontinuously formed, and the width of the raised portion may be set at any suitable value equal to or greater than that of the gap.
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INDUSTRIAL APPLICABILITY
The present invention is applicable to respective structures of a plate cylinder and a blanket cylinder for use in a printing section of various types of rotary presses, such as a web offset press or offset rotary press.
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What is claimed is:
1. A printing cylinder structure for a rotary press, said rotary press including:
a group of ink rolls adapted to sequentially transfer printing ink between adjacent ones of said ink rolls while allowing the printing ink to be formed as an ink film in the course of said transfer;
a plate cylinder having a press plate wound on an outer peripheral surface thereof, said press plate having a printing surface for transferably receiving the ink film from a last one of said ink rolls; and
a blanket cylinder having a blanket wound on an outer peripheral surface thereof, said blanket being adapted to allow the printing ink transferred on the printing surface of said press plate to be transferred onto a surface of a traveling web in a printing manner, said printing cylinder structure being characterized in that:
said blanket cylinder is designed to allow two of the blankets to be wound thereon in side-by-side relation to each other along an axial direction of the blanket cylinder, wherein:
the outer peripheral surface of said blanket cylinder has two gaps formed therein and each adapted to engagingly lock opposite ends of a corresponding one of said blankets, one of said gaps being arranged at a position displaced relative to a position of the other gap in a circumferential direction of said blanket cylinder by a given phase angle; and
the outer peripheral surface of said blanket cylinder or said blankets wound .on said blanket cylinder have two raised portions formed thereon to extend along the axial direction of said blanket cylinder and lie on respective extension lines of said gaps.
2. The printing cylinder structure as defined in claim 1, wherein each of said raised portions is
formed to extend over the entire width of a corresponding one of said blankets at a position except
for respective positions of said gaps.
3. The printing cylinder structure as defined in claim 1, wherein each of said raised portions is
formed to discontinuously extend over the entire width of a corresponding one of said blankets at
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a position except for respective positions of said gaps.
4. The printing cylinder structure as defined in either one of claims 1 to 3, wherein each of said
raised portions is formed to have a width greater than that of a corresponding one of said gaps in
the circumferential direction of said blanket cylinder.
5. The printing cylinder structure as defined in either one of claims 1 to 4, wherein each of said
raised portions is formed to have a curved shape in the circumferential direction of said blanket
cylinder.
6. A printing cylinder structure for a rotary press, said rotary press including:
a group of ink rolls adapted to sequentially transfer printing ink between adjacent ones of said ink rolls so as to form an ink film in the course of said transfer;
a plate cylinder having an outer peripheral surface wound with a press plate which has a printing surface for allowing the ink film to be transferred from a last one of said ink rolls thereonto; and
a blanket cylinder having an outer peripheral surface wound with a blanket adapted to transfer the printing ink transferred on the printing surface of said press plate, onto a surface of a traveling web in a printing manner, said printing cylinder structure being characterized in that:
said blanket cylinder is designed to allow two of the blankets to be wound thereon in side-by-side relation to each other along an axial direction of the blanket cylinder, wherein:
the outer peripheral surface of said blanket cylinder has two gaps formed therein and each adapted to engagingly lock opposite ends of a corresponding one of said blankets, one of said gaps being arranged at a position displaced relative to a position of the other gap in a circumferential direction of said blanket cylinder by a given phase angle; and
the outer peripheral surface of said plate cylinder or said press plate wound on said plate cylinder has two raised portions formed thereon to extend along an axial direction of said plate cylinder and to be periodically located in opposed relation to respective extension lines of said gaps during printing.
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7. The printing cylinder structure as defined in claim 6, wherein each of said raised portions is
formed to extend over the entire width of a portion of the outer peripheral surface of said plate
cylinder or said press plate which is located in opposed relation to a corresponding one of said
blankets at a position except for respective positions of said gaps.
8. The printing cylinder structure as defined in claim 6, wherein each of said raised portions is
formed to discontinuously extend over the entire width of a portion of the outer peripheral surface
of said plate cylinder or said press plate which is located in opposed relation to a corresponding
one of said blankets at a position except for respective positions of said gaps.
9. The printing cylinder structure as defined in either one of claims 6 to 8, wherein each of said
raised portions is formed to have a width greater than that of a corresponding one of said gaps in
the circumferential direction of said blanket cylinder.
10. The printing cylinder structure as defined in either one of claims 6 to 9, wherein each of said
raised portions is formed to have a curved shape in a circumferential direction of said plate
cylinder.
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