JPH0535071B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a multicolor offset printing method for printing a multicolor image using two or more color inks in one step, and in particular to a multicolor offset printing machine and a multicolor offset printing method. The present invention relates to a printing method that shortens the so-called "rise time" from the start of printing in an offset proofing machine to the time when printing is performed with a stable amount of ink.

[Prior Art] Conventional multicolor offset printing is basically performed in the following order of steps.

(1) Apply dampening water to each color printing plate.

(2) The ink supply device applies ink of each color to the corresponding image area of the printing plate.

(3) The ink applied to form a color image on the image area of each printing plate (hereinafter referred to as "color image ink") is transferred to the corresponding blanket.

(4) The color image ink transferred to each blanket is superimposed and transferred onto the surface of a sheet of printing paper in a certain color order so that the printing position of each color image is correctly aligned, and the desired color image is transferred. Obtain color prints.

It is well known that offset printing is used to print on a blanket instead of printing directly from a printing plate onto printing paper, but it is difficult to understand the equipment that performs such multicolor offset printing. For this purpose, the mechanisms and operations of several types of multicolor offset proofing machines will be explained below.

Figure 12 shows a four-color offset proof printing machine (hereinafter referred to as rotary type) that prints multiple colors continuously on sheets of paper, as disclosed in U.S. Patent Nos. 3,536,006 and 3,347,150. FIG. The device has four color printing plates 101a and 101.
A plate cylinder 103 on which printing plates b, 101c, and 101d are mounted in the order in which they are printed, and four blankets 105 corresponding to each color and having the same outer diameter as the plate cylinder 103.
a, 105b, 105c, and 105d in the required order, and a plate cylinder 103.
and has an outer diameter of 1/4 of the blanket body 107,
It is provided with a printing cylinder 109 around which printing paper is mounted. In addition, the subscripts a, b,
c and d represent the ink color to which each member is applied and the order of the colors, and when indicated by only numerical symbols without subscripts, the members are collectively indicated.

In the twelfth illustrated apparatus, while the plate cylinder 103 rotates once in the illustrated arrow direction, each printing plate 101a to
At 101d, dampening water devices 11 corresponding to each color are installed.
Dampening water is supplied from 3a, 113b, 113c, 113d, and then inking devices 111a, 111b, 111c, 111 also correspond to each color.
Printing ink of each color is supplied from d to form a color image on each printing plate.

Each printing plate 10
Color images 1a-101d are transferred to corresponding blankets 105a-105d.

On the other hand, the printing paper is supplied from the paper supply section 115 to the outer periphery of the printing cylinder 109, and the printing paper is fed to the outer circumference of the printing cylinder 109.
While the printing cylinder 109 rotates once, the printing cylinder 109 that rolls in contact with the printing cylinder 109 rotates four times, and each blanket 105a to
The ink of the color image 105d is transferred onto the printing paper in a superimposed manner. The printing paper that has been printed in this one step (four colors) is sent out to the discharge section 117.

Figure 13 shows the document “Deutcher Drucker
33/18-10-1984, pages 47 to 50, is a rotary type four-color offset proofing printing machine similar to the above-mentioned device. The device includes four plate cylinders 121a and 12 on which printing plates of each color are mounted on the outer periphery.
1b, 121c, 121d, and four blanket cylinders 123a, 123b, 123 which have the same diameter as those plate cylinders, have blankets corresponding to each color attached to their outer peripheries, and roll into contact with the outer peripheries of the corresponding color plate cylinders.
c, 123d, and about 3 of the plate cylinder and blanket cylinder.
One printing cylinder 125 with twice the outer diameter is provided. Further, each of the plate cylinders 121a to 121d is provided with an inking device and a dampening water device, respectively. This device supplies ink from each inking device to the printing plate to form a color image, and prints it in a superimposed manner at the same position on the printing paper via a blanket. Similarly, the printing paper supplied from the paper supply section 127 is sent to the outer periphery of the printing cylinder 125, and
As the blanket cylinders 123a to 1 rotate, each blanket cylinder 123a to 1
The color images of the respective color inks are printed in a superimposed manner by passing through the contact portions 23d one after another. The printing paper that has been printed in one process (four colors) is transported to the discharge section 12.
It is discharged at 9.

Next, FIG. 14 shows a four-color offset proof printing machine described in Japanese Patent Application Laid-Open No. 61-66648. Unlike the rotary type of the previous two examples, this is a flatbed type in which the printing plate is mounted in a flat state.

This device includes plate plates 141, 142, 143 on which printing plates for each color are attached to a frame 146;
144, a set of dampening water devices 166 and inking devices 181, 182, 183, 184 for each color
On the other hand, a blanket cylinder 150 with blankets 151, 152, 153, and 154 of each color attached to the outer periphery is mounted on a mount 148 that reciprocates on the upper surface of the frame 146, and a printing cylinder with an outer diameter of 1/4 of the blanket cylinder. 158, dampening roller 160 that supplies dampening water to the water leveling plate 168, dampening rollers 161, 162, 163, 164 for each color, ink rollers 171, 172, 173 for each color,
It is equipped with 174.

When the pedestal 148 moves from the right to the left in the figure, the blanket cylinder 150 is separated from the surface of each plate surface plate 141 to 144, and each dampening water roller 161 to 164 and each ink roller 171
- 174 sequentially contact printing plates of corresponding colors, and dampening water and ink of each color are supplied to the printing plates.

Next, when the pedestal 148 moves from left to right, the color image ink on each printing plate is transferred to each of the blankets 151 to 154 mounted on the blanket cylinder 150. The printing paper is
It is attached to the outer periphery of the printing cylinder 158, and while the blanket cylinder 150 rotates once, the printing cylinder 158 rotates four times while contacting it, and each blanket cylinder 151 to 1
The color images formed on 54 are sequentially transferred to printing paper to perform four-color printing.

FIG. 15 shows a flatbed type two-color offset proofing printing machine described in Japanese Patent Publication No. 59-53871.
In this device, plate plates 112 and 114 for mounting printing plates for each color, a paper plate 116 for mounting printing paper, a dampening water device 132, and inking devices 134 and 136 for each color are arranged in a frame 118. death,
On the other hand, a frame 120 that reciprocates on the upper surface of the frame 118 includes blanket cylinders 122 and 124 for each color with blankets attached to the outer periphery, a set of dampening water rollers 126 (common to each color), and an ink roller for each color. 128, 130.

As the pedestal 120 moves from the right side to the left side in the figure, each plate surface plate 112, 11 moves as in the previous example.
4, dampening water is supplied from the dampening water roller 126 and each color ink is supplied from the ink rollers 128 and 130 to the printing plate surface on the printing plate 4. When traveling in the opposite direction, the color image inks on each printing plate correspond to each other. The image is transferred to the blanket of the blanket cylinder 122 or 124, and then sequentially transferred to the printing paper on the paper surface plate 116 to perform two-color printing.

[Problems to be Solved by the Invention] In the above-mentioned various multicolor offset proofing printing machines, each color image ink is transferred and superimposed on the printing paper by pressing each blanket against the printing paper in order, Four-color or two-color printing is performed. In this case, "reverse trapping" occurs in which the first color ink transferred from the first color blanket to the printing paper comes into contact with the second color or lower blanket surface and is transferred from the printing paper to the subsequent blanket surface. As a result, the amount of ink on the printing paper decreases, making it impossible to obtain the amount of ink needed to obtain the desired printing effect.

That is, in each of the above-mentioned devices, immediately before printing,
Only the ink of the color corresponding to each blanket is transferred, and these blankets sequentially contact a sheet of printing paper. At this time, for example, considering the first color ink, the second color blanket comes into contact with the printing paper immediately after the first color ink is transferred from the first color blanket to the printing paper and is not yet dry. Then, some of the amount of first color ink on the paper is transferred from the printing paper to the second color blanket and reversely transferred.

Similarly, when the printing paper comes into contact with the third and fourth color blankets, the first color ink on the paper surface is reversely transferred to these subsequent blankets, and the printing paper at the time when printing of the four colors is finished. The amount of first color ink on top will be significantly less than that required to achieve the desired print result.

After completing four-color printing on the first sheet of printing paper, the first color ink that has been reverse-transferred from the printing paper is present on the surfaces of the second, third, and fourth color blankets. , the amount of ink is small,
In particular, the number of blanks decreases as the printing order goes to later stages of the blanket. Therefore, when printing on the second printing paper, the first color ink is similarly reversely transferred from the paper surface to the subsequent blanket surface, resulting in a shortage of the first color ink amount in the printed matter.

The same goes for the second and third color inks; the second color ink is reverse-transferred to the third and fourth-color blankets, and the third-color ink is reverse-transferred to the fourth-color blanket. This causes a shortage of ink.

This phenomenon of insufficient amount of ink in the preceding order occurs when the amount of preceding ink on the subsequent blanket surface reaches a certain saturation amount after printing a large number of sheets.
The ink is no longer transferred from the printing paper, and a stable printing condition is obtained from then on, but it is necessary to print a considerable number of sheets before this stable condition is reached, and the printing required for offset proofing is usually Despite the relatively small number of copies,
The amount of printing paper or ink consumed in the preparatory stage until a stable state is reached is extremely large, and a considerable amount of labor is also required during this period.

The present invention relates to a method for overcoming this disadvantage.

[Means for Solving the Problems] In order to solve the above-mentioned disadvantages, the present invention is configured as follows.

Applying corresponding inks to multiple types of printing plates, transferring each ink applied to the printing plates to corresponding blankets, printing each ink on the blankets in a predetermined color order on printing paper,
A multicolor offset printing method that performs multicolor printing, in which each printing plate corresponding to multiple colors of multicolor printing is
an ink application step of applying ink of a corresponding color; a first transfer step of transferring ink from each printing plate to a blanket corresponding to the corresponding color; and after the first transfer step, the preceding color in the color sequence. a second transfer step of transferring ink from the printing plate to a blanket of a color that follows in the color sequence; and a printing step of printing each ink on the blanket transferred in the first and second transfer steps onto printing paper. A multicolor offset printing method consisting of steps.

In the second transfer step, each time the printing plate of the preceding color transfers the subsequent color to one blanket, the ink of the preceding color is supplied to the printing plate of the preceding color, and the ink of the preceding color is transferred to each subsequent blanket. It is desirable to repeat this process as many times as necessary.

[Operation] Before the actual printing, the required amount is printed in advance (hereinafter referred to as "post-printing") on the surface of the blanket to be subsequently printed (hereinafter referred to as "post-printing").
Because the ink (called "pre-printing") is supplied,
At the start of printing, the pre-printed ink on the printing paper is not reversely transferred to the post-printing blanket, which eliminates the inconvenience of insufficient pre-printed ink on the printed matter, ensuring a stable printing condition from the start of printing. Obtainable.

[Example] Figure 1 shows a rotary press 4 for carrying out the method of the present invention.
FIG. 2 is a partially cutaway view showing the end portions of the plate cylinder and blanket cylinder of the apparatus of the same embodiment; FIG. 3 is a side plate showing the second illustrated portion. It is a partial view seen from the outside.

The first illustrated apparatus is broadly divided into a printing section P, a feeder section F that supplies printing paper, and a delivery section D that discharges and stacks printed papers.

The printing section P includes a blanket cylinder 8 on which four blankets 6a, 6b, 6c, and 6d are mounted in a predetermined color order on its outer periphery using a presser member 2 and a winding section 4, and a plate holder 9 on which the outer periphery is mounted. Print version 10
Four plate cylinders 1 are equipped with cylinders a, 10b, 10c, and 10d and have an outer diameter of 1/4 of the blanket cylinder 8.
2a, 12b, 12c, 12d, and plate cylinder 12a
12d and a printing cylinder 14 having the same diameter.

Each plate cylinder 12a to 12d is provided with an ink supply device 16a, 16b, 16c, 16d for each color and a dampening water device 18a, 18b, 18c, 18d.

As shown in the second and third illustrations, each of the plate cylinders 12a to 12d is supported at both ends of its shaft by an eccentric bearing 20, and the eccentric bearing 20 is connected to a rod of an air cylinder 24 mounted on a side plate 22. The plate cylinder 12 is connected to the cylinder 8 and rotated by the expansion and contraction of the rod to move the plate cylinder 12 between a position where it comes into contact with the blanket surface of the blanket cylinder 8 and a position where it is separated from the blanket cylinder 8.

For this movement control, four limit switches 26 are installed at appropriate positions on the side plate 22 and are arranged at different positions in the axial direction of the cylinder corresponding to each color.On the other hand, on the end face of the blanket cylinder 8, In order to engage and operate these limit switches 26 when the barrel 8 is rotated to a desired position, an abutment member 28 is provided whose contact protrusion position is changed according to the corresponding limit switch. Two of these contact members 28 are installed for each limit switch 26, and control the contact and separation of the plate cylinder 12 with respect to the blanket surface.

The ink supply device 16 and the dampening water device 18 may be configured such that they are in constant contact with the corresponding plate cylinder 12, or they are in contact with the plate cylinder 12 only while the plate cylinder 12 is spaced from the blanket cylinder 8. It is also possible to have a configuration in which they touch each other. For this purpose, a configuration similar to a means commonly used in well-known offset printing machines may be applied, so a detailed explanation will be omitted.

The feeder section F is composed of a printing paper supply section 30, a conveyor 36 made up of an endless belt 32 and a plurality of rollers 34, a suction device 38 that feeds the printing paper from the supply section 30 to the conveyor 36, and a swing 40. The suction device 38 has two sets of suction cups 42 and 44, and the suction cup 42 is attached to the supply section 30.
The topmost sheet of printing paper stacked on the conveyor 36 is lifted up, and then the suction cup 44 advances the lifted printing paper to a position where it is caught between the endless belt 32 and roller 34 of the conveyor 36. , transport.

Further, the swing 40 disposed at the end of the conveyor 36 transfers the printing paper conveyed by the conveyor 36 to the drum claw 46 of the printing cylinder 14, and has a structure similar to that of a well-known offset printing machine. apply.

The delivery section D includes a discharge cylinder 15 that rotates in synchronization with the printing cylinder 14 at a position circumscribing the printing cylinder 14, and an endless chain 50 that is wound around the discharge cylinder 15 and has delivery claws 48 mounted thereon at a constant pitch. The pitch of the delivery claws 48 is the same as the pitch between the blankets 6 on the blanket cylinder 8, that is, the pitch is made to match the outer circumference of the printing cylinder 14 and the plate cylinder 12, and the printing paper after printing is delivered from the printing cylinder 14. The materials are received, transported to the discharge section 52, and stored in piles.

Next, the operation of the above-mentioned apparatus will be explained separately in the normal printing time and the preparation stage at the start of work.

During normal printing, the four plate cylinders 12a to 12d and the printing cylinder 14 rotate in synchronization with the rotation of the blanket cylinder 8, and the delivery chain 50 rotates.
rotates through the outer periphery of the discharge cylinder 15.

The printing plate 10 attached to each plate cylinder 12 includes
Dampening water is applied by the dampening water device 18 attached to each, and ink corresponding to each printing color is applied from the ink supply device 16.

When the blanket cylinder 8 rotates and the front edges of the blankets 6a to 6d of each color reach the positions of the corresponding plate cylinders 12a to 12d, the four limit switches 26 activate the two corresponding contact members 2.
The output signal drives the air cylinder 24, rotates the eccentric bearing 20 by the required amount, and brings the plate cylinder 12 into contact with the blanket cylinder 8. "Dodori" is performed. FIG. 1 shows the case where the first color plate cylinder 12a is placed in this state.

When the blanket cylinder 8 further rotates and the rear end of the blanket 6 reaches the position of the plate cylinder 12, the rear part of the abutment member 28 switches the limit switch 26.
air cylinder 24 due to its output signal.
returns to its original position, and the plate cylinder 12 is separated from the blanket cylinder 8.

FIG. 5 is a timing chart showing the raising and lowering of the four plate cylinders 12 during one rotation period of the blanket cylinder 8, and the line at the height of index A indicates the period during which the plate cylinders 12 are separated from the blanket cylinder 8. , the lower line indicates the period of contact with the blanket cylinder. For ease of understanding, the chart shown in Figure 5 has four plate cylinders arranged around each blanket cylinder.
This diagram assumes that the plate cylinders are arranged at equal intervals in degrees of phase, and in the arrangement of plate cylinders shown in the first diagram, each graph line is shifted slightly to the left compared to the one directly above it. will occupy a position.

On the other hand, the printing cylinder 14 is always connected to the blanket cylinder 8.
4 during one rotation of the blanket cylinder 8.
Rotate.

The printing paper is transferred from the supply section 30 to the blanket cylinder 8.
One sheet is sent out every rotation of the suction device 38,
It is supplied to the outer periphery of the printing cylinder 14 via the conveyor 36 and the swing 40, rotates four times together with the printing cylinder, and the four color blankets 6 are sequentially brought into contact with each other.
Four-color printing is performed, and then the delivery claw 48 of the endless chain 50 holds the
is discharged to. In this case, the delivery claw 48 is
Since they are provided at a pitch corresponding to the outer circumferential length of the printing cylinder 14, every fourth one is used.

Although not directly related to the gist of the present invention,
When performing color separation printing to check the printing ink amount and printing condition of each color plate at the same time as proof printing, one sheet per rotation of the printing cylinder 14 (i.e.,
Four sheets of printing paper are fed per rotation of the blanket cylinder 8, and all delivery claws 48 are used for ejection. In this case, it is not necessary to transfer ink to the blanket for after-printing, which will be described later.

Next, a method of supplying ink to the blanket of the post-printing color by each printing plate of the pre-printing color of the present invention in the rotary type four-color offset proofing press having the above-mentioned configuration will be explained.

FIG. 6 is a timing chart showing the basic concept of the method of the present invention, and shows the relationship between the contact and separation of each plate cylinder 12 with respect to the blanket cylinder 8 during the preparation work at the stage before actually starting printing. Similarly to FIG. 5, for ease of understanding, four plate cylinders are shown arranged at equal intervals with a phase of 90 degrees.

During one rotation of the blanket cylinder 8, the first color plate cylinder 12a is inserted into the second, third, and fourth color blankets 6b, 6c, and 6d, and the second color plate cylinder 12b is inserted into the second color blanket 6b, 6c, and 6d. 3 and 4 Blanket 6 of each color
The third color plate cylinder 12c is inserted into cylinders c and 6d.
The image ink of each color is transferred to the blanket 6d of the fourth color for the required afterprinting. If you apply the required amount of color image ink to the post-printing blanket and print using the same procedure as the normal printing described above, the same condition will be obtained at the beginning of printing as if a certain number of sheets had been printed. In other words, a state equivalent to that of the pre-printed color image ink being reverse-transferred from the printing paper and saturated on the post-printed blanket surface is obtained,
Further, it is possible to prevent the ink for the pre-printing from being reversely transferred from the printing paper to the blanket for the post-printing, and it is possible to obtain stable and high-quality printed matter.

Next, preferred implementation means of the method of the present invention will be explained in more detail.

First, before transferring ink from the printing plate for pre-printing onto the blanket for post-printing, each printing plate 10 is attached to the plate cylinders 12a to 12d according to the illustration in FIG.
Blankets 6a to 6 of corresponding colors from a to 10d
Each color image ink is transferred to d. The reason why the original color image ink is transferred to each blanket in this way is as follows.

In other words, when printing a halftone image made up of halftone dots in multiple colors, each halftone dot is different from halftone dots of other colors, especially in image areas where the area ratio occupied by the halftone dots is large, that is, the halftone dot percentage is large. Prints are partially overlapped. In this case, multiple colors of ink should overlap on the blanket, but in reality there is ink that was applied earlier on the blanket, and ink of a different color is layered on top of it. When supplied, the later ink is repelled by the earlier ink and cannot adhere to the blanket surface, meaning that it cannot exist in an overlapping state.

Therefore, in order to accurately apply the appropriate amount of ink of the color that should originally be printed on each blanket, printing is performed on each of the blankets 6a to 6d during normal printing according to the above-mentioned procedure. Color ink is transferred and applied in advance.

Next, the ink of the preprint color is transferred to the postprint blanket by the preprint printing plate. This is done while the blanket cylinder 8 rotates three times, ie, in three steps, as shown in FIGS. 8-1 to 8-3. Note that, similarly to Figures 5 and 6 above, these graphs also show the case where the positions of each plate cylinder are arranged at equal intervals around the blanket cylinder at a 90 degree phase for ease of understanding. It is shown as follows.

In the first rotation period of the blanket cylinder 8,
As shown in Figure 8-1, the first color printing plate 12a is placed on the second color blanket 6b, and the second color printing plate 1 is placed on the second color blanket 6b.
2b is brought into contact with the third color blanket 6c, and the third color printing plate 12c is brought into contact with the fourth color blanket 6d, respectively.

In the second rotation period of the blanket cylinder 8,
As shown in Figure 8-2, the first color printing plate 12a is placed on the third color blanket 6c, and the second color printing plate 1 is placed on the third color blanket 6c.
2b are brought into contact with the fourth color blanket 6d, respectively.

Further, in the third rotation period of the blanket cylinder 8, the printing plate 12a of the first color is brought into contact with the blanket 6d of the fourth color, as shown in Figure 8-3.

The means for transferring ink from the pre-printed printing plate to these post-printing blankets can also be carried out by the method shown in FIG. 6, but for the following two reasons, 3 of each illustration
It is more preferable to carry out the process in a step.

The first reason is the problem of ink supply amount. For example, according to the operation shown in FIG. 6, the printing plate 10a of the first color will continuously supply ink to the three blankets of the second color and below, so that the printing plate 10a of the first color will have a higher transfer rate. The amount of ink used will decrease, resulting in a shortage of ink. The same can be said of not only the first color printing plate 10a but also the second and third color printing plates 10b and 10c.

The second reason is the dampening solution problem. According to the method shown in FIG. 6, for example, the fourth color blanket 6d has the first to third color printing plates 10a to 1
Ink is continuously transferred from 0c, and at this time, not only ink but also dampening water is transferred from each printing plate. That is, in the case of lithographic printing plates, dampening water is supplied to prevent ink from adhering to areas other than the printed areas, and this dampening water is also transferred to the post-printing blanket. . However, the position where the ink for after-printing supplied to the after-printing blanket should adhere is, of course,
Because it is different from that of the ink for the pre-printing, the fourth
This means that dampening water transferred from the printing plate of the previous printing is present in the color blanket at the position where the ink is transferred. In the case of the continuous operation shown in Figure 6, the ink for the after-printing is supplied by the time the dampening water transferred from the printing plate for the first printing to the blanket evaporates, and the ink for the after-printing is sufficiently transferred. Otherwise, the amount of ink will be insufficient. this is,
Not only the fourth color blanket 6d, but also the third color,
The same can be said of the second color blankets 6c and 6b.

Therefore, as shown in the above-mentioned 8th figure, ink is applied to each printing plate every rotation period during the period in which the blanket cylinder 8 rotates three times, based on the first color that has been transferred the most times to each blanket in post-printing. If the color image ink is transferred to any one of the applied and post-printed blankets, ink can be evenly supplied to each of the blankets 6a to 6d, and the blanket cylinder 8 rotates once. During this process, the dampening water applied to each blanket surface can be sufficiently evaporated in the same way as in normal lithographic printing, so it is possible to eliminate the above-mentioned problem of hindering the transfer of ink for post-printing. .

After completing the above process, start actual printing. In this case, as described above, during one rotation period of the blanket cylinder 8, the printing plates 10a, 10B,
Blanket 6a corresponding to 10c, 10d,
The ink is transferred to the blankets 6b, 6c, and 6d, and then the color image ink on these blankets 6a to 6d is transferred in a layered manner to the printing paper wound around the printing cylinder 14, and this operation is repeated.

In addition, if the printing plate is a dry type that does not require the use of dampening water, and the ink supply device is configured to be able to continuously supply a sufficient amount of ink, then The method shown in Figure 6 can be applied to apply ink for the pre-printing, or as shown in Figure 7, ink of the original printing color can be applied to each blanket during one rotation period of the blanket cylinder. It is also possible to transfer the ink of the preceding color and the ink of the preceding color at the same time.

Note that the amount of ink supplied to the post-printing blanket is sufficient as long as the amount of ink printed on the printing paper is not reversely transferred to the post-printing blanket during subsequent normal printing. , the amount required to feed the original blanket is less than that required for normal printing. Therefore, in the above-mentioned embodiment, ink is transferred to the blanket for post-printing once, but ink is transferred to the original blanket twice, at the initial preparation stage and when actually printing. Alternatively, the amount of ink supplied can be changed by performing the ink supply an appropriate number of times as necessary before actual printing is performed.
That is, the number of times a printing plate of a certain color contacts the corresponding original color blanket is greater than the number of times it contacts the post-printing blanket, thereby changing the amount of ink of the original color supplied to the blanket. There is.

The means for changing the amount of ink is not limited to the above-mentioned method, but may include means for changing the number of rotations of contact between the ink supply device and the printing plate when ink is applied to each printing plate from the ink supply device, It is also possible to employ means generally applied to adjusting the amount of ink in printing presses, such as means for adjusting the amount of ink supplied from an ink fountain or the like to the ink supply device.

The above-mentioned adjustment and control of the amount of ink supplied to the blanket is also applied to the flat multicolor offset proofing press of the embodiment described below.

Next, FIG. 4 is a schematic sectional view showing an embodiment of the method of the present invention to which a flat type four-color offset proof printing machine is applied.

The fourth illustrated device includes first to fourth color plate plates 21a, 21b, 21c, and 21d and a paper platen 23.
A pedestal 27 is configured to reciprocate on the upper surface of a frame 25 on which blanket cylinders 29a, 29 of the first to fourth colors are mounted.
b, 29c, 29d, ink roller 31a, 3
A dampening water roller 33 that commonly supplies dampening water to each of the printing plates 1b, 31c, and 31d is mounted so as to run together with the pedestal 27. On the other hand, a damping device 35 for supplying dampening water to the dampening water roller 33 is arranged at the left end of the frame 25 . Further, on the right side of the frame 25, inking devices 37a, 37b for the first to fourth colors,
37c and 37d are the ink rollers 31a to 37d.
It is arranged at a pitch corresponding to the arrangement of 31d,
These inking devices 37a to 37d constitute an ink supply device.

To perform normal proof printing with the apparatus shown in the fourth figure, it operates as follows.

First, the printing plates 41a to 41d of a predetermined color are mounted on each of the plate plates 21a to 21d, and the printing paper is mounted on the paper platen 23, respectively.

When the pedestal 27 reciprocates on the frame 25,
At the left end of the reciprocating stroke, the dampening water roller 33 engages with the damping device 35 to supply dampening water, and at the right end of the stroke, each of the ink rollers 31a to 31d connects to the corresponding inking device 37a to 37d. , the ink of a predetermined color is supplied, and as the pedestal 27 travels, the printing plates 41a to 41 mounted on the respective plate plates 21a to 21d are
d, dampening water is supplied from the dampening water roller 33, and ink of a predetermined color is supplied from each of the ink rollers 31a to 31d.

Further, the ink on the surfaces of each printing plate 41a to 41d is transferred to the blanket cylinder 29 for the corresponding printing color when the pedestal 27 moves back (travels from left to right).
transferred to the peripheral surfaces of a, 29b, 29c, 29d,
Next, the image is transferred to the printing paper 51 mounted on the paper surface plate 23, and multicolor printing is performed.

FIG. 9 is a timing chart showing the lifting and lowering operations of the respective blanket cylinders 29a to 29d when the gantry 27 moves from left to right in the above process, and each blanket cylinder moves to the corresponding plate plate. The color image ink of the printing plate mounted on the plate is transferred, and then
It descends to a position facing the paper surface plate and transfers ink to the printing paper to perform printing.

In the above-mentioned operation, the means for raising and lowering each blanket cylinder at a required position is a means using a plate cam and a limit switch engaged with the plate cam, in accordance with the method commonly used in this type of flat type offset proofing printing press. However, since such a mechanism is a known means disclosed in, for example, Japanese Patent Publication No. 59-53871, detailed explanation will be omitted.

The above is a case of ordinary multi-color printing using the apparatus shown in the fourth figure, but the method of supplying color image ink for pre-printing to a post-printing blanket according to the method of the present invention is carried out as follows. .

Figure 10 shows the basic implementation means.
When the frame 27 moves from the left to the right in FIG. 4, the fourth color blanket cylinder 29d is inserted into the third, second, and first color plate plates, The three color blanket cylinders 29c are inserted into the plate plates of the second and first colors, and
The color blanket cylinder 29b is inserted into the plate plate of the first color, and the image ink of each color for the first printing is transferred to the blanket for the second printing.

Next, a more preferable implementation means of the method of the present invention using the above-mentioned apparatus will be explained.

First, as in the case of the rotary proof printing machine shown in the first diagram, each printing plate mounted on the plate platens 21a to 21d, prior to transferring the color image ink from the pre-printing printing plate to the post-printing blanket. Editions 41a-4
1d, color image inks are transferred onto the circumferential surfaces of the blanket cylinders 29a-29d of the printing colors to which they originally correspond. Each blanket body 29 at this time
The lifting and lowering operations of a to 29d are similar to those during normal printing shown in FIG. 9, but the paper surface plate 23 is not lowered.

Ink is then transferred from the pre-printed printing plate to the post-printed blanket. In this case, it is preferable to perform the ink transfer in three steps, as in the preferred embodiment of the rotary type device described above.
The outline is shown in Figure-1 to Figure 11-3.

During the first run of the gantry 27 from the left to the right, as shown in Figure 11-1, the ink from the first color printing plate 41a is transferred to the second color blanket cylinder 29b.
Then, the ink of the second color printing plate 41b is transferred to the third color blanket cylinder 29c, and the ink of the third color printing plate 41c is transferred to the fourth color blanket cylinder 29d.

Then, during the second run, as shown in Figure 11-2, the ink on the printing plate 41a of the first color is transferred to the third printing plate 41a.
The second color printing plate 4 is placed on the color blanket cylinder 29c.
The ink of 1b is applied to the fourth color blanket cylinder 29d.
transcribe each.

Furthermore, during the third run, as shown in Figure 11-3, the ink of the first color printing plate 41a is transferred to the fourth printing plate 41a.
The color is transferred to the colored blanket cylinder 29d.

Thus, after the pre-printing ink is transferred to the post-printing blanket through the above three steps,
A required multicolor proof print can be obtained by performing normal printing according to the illustration in FIG. 9 above.

[Effects of the invention] (1) Eliminates the inconvenience that during the printing start period of multicolor offset printing, the ink of the preprint is reversely transferred from the printing paper surface to the blanket of the postprint, resulting in insufficient amount of preprint ink in the printed matter. can do.

(2) It is possible to create a saturated state equivalent to the stable printing state after the printing start period in the normal printing process without actually printing on printing paper, reducing the waste of materials and labor. You can save money.

(3) Especially in proofing presses that only print a relatively small number of copies, stable conditions can be achieved quickly, saving printing paper and
Work efficiency can be greatly improved.

[Brief explanation of the drawing]

1 to 3 are schematic diagrams of a rotary type offset proofing printing machine for carrying out the present invention, FIG. 4 is a schematic diagram of a flat type offset proofing printing machine, and FIGS. FIGS. 9 to 11 are timing charts showing the operation of each plate cylinder in the illustrated rotary offset proofing press; FIGS. 1 to 15 are diagrams showing conventional devices, respectively. 6a-6d... Blanket, 8... Blanket cylinder, 10a-10d... Printing plate, 12a-12d...
Plate cylinder, 14... Printing cylinder, 16a-16d... Ink supply device, 21a-21d... Plate surface plate, 23... Paper surface plate, 29a-29d... Blanket cylinder, 31a-
31d... Ink roller, 37a-31d... Inking device, 41a-41d... Printing plate.

Claims (1)

[Claims] 1. Applying corresponding inks to printing plates of a plurality of colors, transferring each ink applied to the printing plates to a corresponding blanket, and printing each ink on the blanket in a predetermined color order. A multicolor offset printing method in which multicolor printing is performed by printing on paper, and each printing plate that supports multiple colors for multicolor printing is
an ink application step of applying ink of a corresponding color; a first transfer step of transferring ink from each printing plate to a blanket corresponding to the corresponding color; and after the first transfer step, the preceding color in the color sequence. a second transfer step of transferring ink from the printing plate to a blanket of a color that follows in the color sequence; and a printing step of printing each ink on the blanket transferred in the first and second transfer steps onto printing paper. A multicolor offset printing method consisting of steps. 2. In the second transfer step, each time the printing plate of the preceding color transfers the subsequent color to one blanket, the ink of the preceding color is supplied to the printing plate of the preceding color, and the ink of the preceding color is transferred to each subsequent blanket. 2. A multicolor offset printing method according to claim 1, wherein said steps are repeated sequentially a required number of times.