JP4379871B2 - Blanket for printing combined with thickness adjusting body and mounting method thereof - Google Patents

Description

  The present invention relates to a printing blanket in which a thickness adjusting material is combined in advance when mounting on a blanket cylinder of an offset printing press, and a mounting method for mounting in combination with a thickness adjusting material.

  In an offset printing machine, a blanket for printing with a surface printing layer on the printing plate side is mounted on the blanket cylinder, dampening water is supplied from the water supply device to the printing plate, and ink is supplied from the inking device. The ink image is transferred to a blanket, and the image transferred to the blanket is printed on a printing paper passing between the impression cylinders. For such a printing blanket, a compressible printing blanket provided with a compressible layer is generally used, but an incompressible printing blanket without a compressible layer can also be used. When these printing blankets are loosened or displaced after being mounted on the blanket cylinder, the image is displaced. For this reason, the blanket must not only be easily mounted on the blanket cylinder, but also must be securely fixed after mounting.

  Conventionally, when attaching a blanket for offset printing to a blanket cylinder of an offset printing machine, aluminum or aluminum is attached to both ends of the blanket for easy and reliable installation when inserting both ends of the blanket into slits formed in the blanket cylinder. A mounting bar having a substantially U-shaped cross section made of iron is swaged and locked in the slit. That is, as shown in FIGS. 3 and 4, both end portions of the blanket 1 are inserted and fixed to the mounting bar 2, and the mounting bar 2 to which the blanket is fixed is rotatably mounted in the slit 4 of the blanket cylinder 3. The blanket 1 is inserted into the winding bar 5 and tightened by being fitted into the mounting groove 6 of the winding bar 5 and then rotating the worm 7.

On the other hand, the thickness of the printing blanket is manufactured to a predetermined thickness. However, when the printing blanket is mounted on the blanket cylinder of a printing press, the distance between the blanket cylinder and the plate cylinder is larger than the blanket thickness (the blanket cylinder). Thickness adjustment body (paper, sheet, under blanket, etc.) is placed under the blanket as an underlay material, and the thickness is raised and adjusted. ing. The tightening tension when the blanket is attached to the blanket cylinder is generally tightened with a tension of 1.8 to 2.2% from a flat state where no tension is applied.
Japanese Patent Application Laid-Open No. 2004-042503 JP 2003-305967 A

  However, conventionally, when it is interposed under the blanket as a thickness adjusting body, it is not fixed to the blanket or the blanket cylinder simply by being interposed as shown in FIG. Alternatively, the tail end of the thickness adjusting body is fixed to the blanket cylinder separately from the blanket, and the tail end side is not fixed to the blanket cylinder. Moreover, although it is going to fix by making it longer than the printing surface of a blanket cylinder, a thickness adjustment body may move or break during printing. When this occurs, the portion becomes overpressure, which causes the ink to be deposited at that location differently. In order to prevent such a thickness adjusting body from moving or breaking, the blanket is actually tightened with a tension stronger than the tightening tension recommended by the blanket manufacturer.

  When tightening tension is increased, the blanket on the edge side of the blanket cylinder and the edge on the edge side of the blanket cylinder is less compressible because the compression layer is crushed than other parts, and contacts the plate cylinder and impression cylinder during rotation. At this time, a problem called shock eyes (shock marks) in which the vibration affects the marking surface is generated. Further, the compressibility in the vicinity of the edge portion is lowered, and the load on the edge portion during printing is increased, so that the inking property of the edge portion is lowered.

  Therefore, the present invention has been made to solve such a problem. The blanket and the thickness adjusting body are integrally fixed at the tail end portion, and the thickness adjusting body is provided at the tail end portion. The purpose of the present invention is to provide a printing blanket combined with a thickness adjusting body that prevents the movement (displacement) and breakage of the thickness adjusting body and suppresses the occurrence of shocks, and a mounting method thereof. To do.

  In order to achieve the above object, the present invention is configured as follows. That is, the printing blanket combined with the thickness adjusting material according to the present invention is a printing blanket combined with the printing blanket and the thickness adjusting body, and the printing blanket and the thickness are arranged at the tail end side. The height adjusting body is integrally fixed to the mounting bar, and only the printing blanket is fixed to the mounting bar at the tail edge side end. By fixing the blanket and the thickness adjusting body together at the tail end side, the thickness adjusting body does not move or break during printing.

The thickness adjusting body has a tail edge side end portion positioned between the printing surface of the printing blanket that is actually printed and the edge portion of the blanket cylinder. That is, at least the thickness adjusting body needs to be positioned on the lower surface of the printing surface. The length of the thickness adjusting body may be a length at which the tail edge side end portion is located between the printing effective surface and the edge portion of the blanket cylinder, which is a range where printing is effectively performed on the printing blanket. As described above, when the end of the thickness adjusting body has a length located between the printing effective surface and the edge of the blanket cylinder, the position of the printing surface of the printing blanket can be changed by replacing the printing plate. Even in this case, the thickness adjuster is in the range of the printing surface, and the printing quality can be maintained.

  Further, the mounting method of the printing blanket combined with the thickness adjusting body according to the present invention is a mounting method of the printing blanket that is mounted by interposing the thickness adjusting body under the printing blanket. The blanket for printing and the thickness adjustment body were fixed to the mounting bar as a single unit, and the tail end was assembled by fixing only the printing blanket to the mounting bar. The mounting bar is attached to a winding bar disposed in the slit of the blanket cylinder, and the blanket is fastened with a tension of 1.2 to 2.0%. By fixing the blanket and the thickness adjusting body together at the end of the gripping side, the thickness adjusting body does not move or break during printing, and the blanket and the thickness adjusting body It can be easily installed.

It is preferable to mount the tail edge side end portion of the thickness adjusting body so as to be positioned between the printing surface on the printing blanket and the edge portion of the blanket cylinder. Further, the tail edge side end portion of the thickness adjusting body may be mounted so as to be positioned between a printing effective surface that is an effective printing range in the printing blanket and an edge portion of the blanket cylinder. . As described above, by always positioning the tail edge side end portion of the thickness adjusting body within the range of the printing effective surface of the printing blanket, the printing quality is maintained and the plate can be replaced.

  As described above, according to the blanket of the present invention, since the blanket and the thickness adjusting body are integrally fixed on the gripping side, the thickness adjusting body does not move (displace) during printing. Therefore, the tension at the time of mounting on the blanket cylinder can be weakened, and the compressibility is not weakened near the edge of the blanket cylinder. For this reason, it is possible to suppress the occurrence of shock eyes caused by a decrease in compressibility. Moreover, since the decrease in the thickness in the vicinity of the blanket cylinder edge portion is suppressed, the durability of the blanket is also improved.

  Hereinafter, the illustrated embodiment will be described in detail. FIG. 1 is a side view for explaining a printing blanket combined with a thickness adjusting body according to the present invention, and FIG. 2 is a cross-sectional view of an essential part of a blanket cylinder equipped with a printing blanket combined with a thickness adjusting body. As shown in FIG. 1, the combination printing blanket 10 has an end portion 8 of the printing side fixed integrally with one end portion of the printing blanket 11 and the thickness adjusting body 12 by a mounting bar 20 made of aluminum or iron. Thus, only the printing blanket 11 is fixed to the mounting bar 21 at the tail edge 9 at the other end. In order to fix the printing blanket 11 and the thickness adjusting body 12 to the mounting bar 20, not only the physical fixing force is increased by caulking, but also the fixing force is increased by the adhesive force of the adhesive. Also good. The same applies to the fixing between the printing blanket 11 and the mounting bar 21.

In the above embodiment, since the mounting bar 20 and the mounting bar 21 are the same, the thickness is adjusted by cutting a part of the thickness of the printing blanket 11, and the cut portion and the thickness are adjusted. Although fixed integrally with the adjusting body 12 is, when using the large insertion opening of the mounting bar 20, the thickness without adjusting the thickness of cut part thickness of the printing blanket 11 The thickness adjusting body 12 may be fixed integrally. Further, the thickness adjuster 12 is not limited to the under blanket, and may be any material that can be used as a normal underlay material such as paper or film having a uniform thickness.

In order to mount the printing blanket 11 and the thickness adjusting body 12 on the blanket cylinder, as shown in FIG. 2, the printing blanket 11 and the thickness adjusting body 12 are integrally fixed to the mounting bar 20 and the gripping side. On the other end side, only the printing blanket 11 is fixed to the mounting bar 21 to form the tail edge side end 9, and thus the printing blanket 11 and the thickness adjusting body 12 are connected to each other. After the assembly, the mounting bars 20 and 21 are fitted into the mounting grooves 6 of the winding bar 5 disposed in the slit 4 of the blanket cylinder 3, and then the worm 7 is driven to rotate so that the degree of expansion of the blanket is 1. Tighten with a tension of 2 to 2.0%.

  The blanket is stretched in a flat state where no tension is applied. A blank line of 100 to 200 mm is drawn in the length direction of the blanket surface (circumferential direction when wrapped around the blanket cylinder) and attached to the blanket cylinder. Then, the measurement may be performed by measuring the length of the marked line when the tension is applied. The elongation at this time is set to 1.2 to 2.0%.

(Relationship between degree of stretch and shock (streaky defect))
In the blanket of the comparative example, only the printing blanket is fixed to the mounting bar, and in the first and second embodiments, as shown in FIG. 1, the printing blanket and the under blanket as the thickness adjusting body are used as the mounting bar. It was fixed to the tail end, and at the tail end, only the printing blanket was fixed to the mounting bar.

  The printing conditions and the measuring equipment used are as follows. The printing machine uses Komori Corporation's Lithlon 26, the printing speed is 10,000 sheets / hour, the printing pressure is P / B = 0.10 mm, B / I = 0.15 mm, and the printing plate has a halftone dot of 75% in total. The ink is indigo M and red M from Toyo Hi-Echo, the paper is art paper (76.5 kg), the density meter is Gretag D196, the standard density is indigo 1.45 to 1.50, red 1.30 to 1. .35.

  The test method was performed as follows. First, the degree of stretch of the blanket at the time of printing is set to 2.0%, which is generally performed in Example 1 and the comparative example, and Example 2 is a dedicated torque wrench so as to be 1.2% which is 30% lower than general. Tightened with and attached. Thereafter, printing is performed at a printing speed of 10,000 sheets / hour, and when about 100 sheets are printed, the printing machine is stopped. Here, for the purpose of correction, tightening was again adjusted with a dedicated torque wrench.

75% dot printing is performed while adjusting the ink supply amount, and the density is adjusted to the reference density. The densitometer was measured using Gretag D196. 210 sheets or more are printed (density adjustment is finished during this time), and 20 to 190 to 209 printing sheets are collected. The color difference (ΔE * ab) of the collected printing paper near the shock eyes and the shock eyes was measured. A shock eye is a phenomenon in which a portion having a high density in the form of a horizontal streak occurs in a uniform density portion. The larger the difference in density, the clearer the shock eye is confirmed.
These measurement results are shown in Table 1.

  When Example 1, Example 2 and Comparative Example 1 were compared, the concentration of the shock eye was highest in Comparative Example 1 and lowest in Example 2. Therefore, it can be seen that the use of the under blanket reduces the shock, but the shock is further reduced by lowering the tightening tension.

(Relationship with the length of the under blanket)
A printing blanket and an under blanket as a thickness adjuster are fixed to the mounting bar to be the end on the tail side, and at the tail edge side end, only the printing blanket is fixed to the mounting bar. Three types with different under blanket lengths were formed. The under blanket with a length of 568 mm was designated as Example 3, the one with a length of 571 mm was designated as Example 4, and the one with a length of 574 mm was designated as Example 5. The measuring equipment and the measuring method were the same as in Example 1.

As shown in FIG. 2, the third embodiment has a length of 2 mm on the printing surface E2 side to be actually printed. In the fourth embodiment, the tail edge side E and the printing effective surface (effective printing) In Example 5, the length was 2 mm closer to the slit 4 side than the edge portion E. The printed state on the tail edge side of this printed matter was measured visually. These measurement results are shown in Table 2.

  As described above, in Example 3, since the end portion of the under blanket is 2 mm on the printing surface E2 side, a decrease in the thickness was caused in the 2 mm portion where the under blanket was not interposed. Moreover, in Example 5, when mounting on the blanket cylinder, the under blanket is fixed at the edge portion on both the gripping side and the tailing side of the blanket cylinder. Since both ends of the under blanket are fixed, the under blanket does not have the same degree of expansion as the printing blanket, and therefore, there is a problem that the under blanket breaks when the printing blanket is tightened. Accordingly, the length of the under blanket is preferably such that the end on the tail edge side is between the edge portion and the printing surface, or between the edge portion and the printing effective surface.

It is a side view which shows an example of the printing blanket which combined the thickness adjustment body. It is principal part sectional drawing of the blanket cylinder which mounted | wore with the printing blanket which combined the thickness adjustment body. It is a side view which shows the relationship between the conventional printing blanket and a thickness adjustment body. It is principal part sectional drawing of the blanket cylinder which showed mounting | wearing with the conventional printing blanket and the thickness adjustment body.

Explanation of symbols

4: slit 5: entrainment bar 6: mounting groove 7: worm 8: tail end 9: tail end 10: combination printing blanket 11: printing blanket 12: thickness adjusting body 20, 21: Mounting bar

Claims (2)

  A blanket for printing, which is a combination of a blanket for printing and a thickness adjuster, with the blanket for printing and the thickness adjuster integrally fixed to the mounting bar at the tail end, In the printing section, a printing blanket combined with a thickness adjusting body characterized in that only the printing blanket is fixed to the mounting bar. A printing blanket mounting method in which a thickness adjusting body is mounted under the printing blanket, and the print blanket and the thickness adjusting body are fixed to the mounting bar integrally at the gripping side end. The tail end of the tail edge is assembled by attaching only the printing blanket to the mounting bar. A printing blanket mounting method combined with a thickness adjusting body characterized in that tightening is performed with a tension of 1.2 to 2.0%.

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