JP2521038B2 - Gravure printing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gravure printing method for printing a pattern on a gravure cylinder at arbitrary intervals.

(Prior Art) In gravure printing, ink is supplied to the cylinder surface while rotating a cylinder having cells formed on the surface by corrosion or engraving, and the ink is scraped off by a doctor fixed at a predetermined position. The ink is left only in the inside, and the sheet that is continuously supplied is pressure-bonded to the cylinder with an impression cylinder whose surface is made of rubber, and only the ink in the cells of the cylinder is transferred to the sheet, thereby forming the sheet. A pattern, which is a set of cells on a cylinder, is printed.

In the case of multicolor printing, after printing the first color on the sheet by the above method, print the second color on the part where the first color is printed, and then print a predetermined number of colors in the same manner. Done by.

In this gravure printing, the cylinders for a predetermined number of colors arranged in sequence are rotated at a constant speed, and the sheets are continuously fed from the winding state while the sheets are pressed against the cylinder surface by an impression cylinder. Print on the sheets one after another,
The printed sheet is rewound to speed up the printing. Therefore, the pitch of the pattern to be printed is determined by the circumference of the cylinder, and in the case of multicolor printing, the cylinder having the same diameter is used.

By the way, the patterns of the patterns to be printed are various, and the colors do not overlap each other even in multicolor printing, for example, the patterns A, B and C repeatedly appear at regular intervals as shown in FIG. In the past, such patterns were also printed by the same method as above.
That is, three cylinders having a circumference having the same length as the pitch L of the pattern are used, cells corresponding to the patterns A, B, and C are formed in each cylinder, and the cylinders are sequentially arranged. I was overprinting.

(Problems of Prior Art) FIGS. 5 (a) and 5 (b) are an external view and a cross-sectional view of a cylinder corresponding to the pattern A described above. Cylinder as shown in the figure
The surface of 25 is the cell IA in only about 1/3 of the circumferential direction.
Will be formed. When such a cylinder 25 supplies ink to its surface and scrapes it off with a doctor,
There was a problem that the ink on the part where the cell IA was not formed was insufficiently scraped off, and the ink that could not be scraped off was transferred to the sheet and was easily stained. Further, with respect to the above pattern, as the number of colors increases, the cylinder circumference increases, the cylinder cost increases, the workability of cylinder replacement deteriorates, and the number of colors that can be printed is reduced due to mechanical restrictions. There was a limit to the size of each design.

(Object of the Invention) The present invention has been made in view of the above points, and minimizes a portion of a cylinder surface where cells are not formed,
An object of the present invention is to provide a method for printing a pattern on the surface of a cylinder at an arbitrary interval so that a border is beautifully printed.

(Summary of the Invention) In order to achieve the above object, the present invention is to press a sheet continuously supplied onto a surface of a gravure cylinder that rotates with an impression cylinder, and to apply ink in cells on the gravure cylinder to the surface of the sheet. By alternately repeating the step of transferring to the gravure cylinder and releasing the pressure of the impression cylinder and sending the sheet by a certain amount without contacting the surface of the gravure cylinder. A gravure printing method for printing on the surface of a sheet, characterized in that a flat portion having no narrow cells is provided on the surface of the gravure cylinder along the axial direction of the gravure cylinder.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

1 (a) and 1 (b) are explanatory views of a printing method showing an embodiment of the present invention, in which 1U, 2U, and 3U indicate printing units, 1, 2, and 3 indicate gravure cylinders, and 4 Is a doctor, 5 is an ink pan, 10 is an impression cylinder, and W is a sheet.

First, the sheet W supplied from a supply device (not shown)
Is sent to the printing unit 1U, is guided between the gravure cylinder 1 and the impression cylinder 10 through the guide rolls 20 and 20 and the elevating roll 11, and after the pattern of the gravure cylinder 1 is printed, the elevating roll 12, It is dried by the dryer 13 via the guide roll 20, further cooled by the cooling roll 14, and guided to the next printing unit 2U via the guide roll 20, the compensator roll 15, and the guide roll 20. Similarly, in the printing unit 2U, the gravure cylinder 2
Of the gravure cylinder 3 is printed on the sheet W in the printing unit 3U. The sheets W printed in this way are successively wound by a winding device (not shown).

 The next printing operation will be described in detail.

In the printing unit 1U, the gravure cylinder 1 is dipped in the ink in the ink pan 5. 4 (a) and 4 (b) show an external view and a sectional view of the gravure cylinder 1, and most of the surface of the gravure cylinder 1 is a cell.
Although Ia is formed, a narrow flat section Ib without cells is provided along the axial direction of the cylinder. As the gravure cylinder 1 rotates, the ink once applied to the cylinder surface is scraped off by the doctor 4 in front of the impression cylinder 10, so that the ink remains only in the cell Ia at the position in contact with the impression cylinder 10. It will be.

First, when the flat portion Ib of the gravure cylinder 1 reaches the position where it is crimped by the impression cylinder 10, the impression cylinder 10, the elevating rolls 11 and 12 are lowered and the sheet W is gravure cylinder 1 as shown in FIG. 1 (a). When the gravure cylinder 1 makes one rotation in this state and the flat portion Ib reaches the position of the impression cylinder 10 again in this state, as shown in FIG.
11 and 12 rise, and in this state, the gravure cylinder 1 rotates two more times. Similarly, in the printing unit 2U and the printing unit 3U, the impression cylinders 10 and 10, the elevating rolls 11 and 11, according to the rotation of the gravure cylinder 2 and the gravure cylinder 3,
12, 12 goes up and down. Further, the impression cylinder 10 and the elevating roll of each printing unit are moved up and down at the same time. That is, each gravure cylinder makes one rotation in the state shown in FIG. 1 (a), and each gravure cylinder makes two rotations in the state shown in FIG. 1 (b). The above operation is 1
As a cycle, each printing unit repeats this cycle. Further, although the respective impression cylinders and the elevating rolls repeatedly ascend and descend, the gravure cylinders having the same diameter are used and are constantly rotating at the same speed, and the sheet W is continuously rotated at the same speed as the peripheral speed of the gravure cylinder. Running. At this time, if the raising and lowering rolls 11 and 12 and the bearing portion of the impression cylinder 10 are integrally formed, the raising and lowering rolls 11 and 12 ascend and descend with the rise of the impression cylinder 10 and the sheet W is not pulled or sagged. It moves up and down in close contact with the impression cylinder 10.

Next, the state of the sheet W printed by the above operation will be described.

2 (a), (b), and (c) show the state of the sheet W printed by each printing unit 1U, 2U, 3U in the first cycle, and FIGS. 3 (a), 3 (b), (C) shows the state of the sheet W printed by each printing unit 1U, 2U, 3U in the next one cycle.

Here, the circumference of each gravure cylinder is 1, and the path length of each printing unit is set to 1 (3n-1) (n represents an integer). The path length can be adjusted by moving the compensator roll 15 shown in FIG. 1 in the horizontal direction. Gravure cylinder 1, 2, 3
Is rotating in phase with each other.

In the figure, A, B, and C are gravure cylinders 1,
2 and 3 represent the pattern printed on the sheet W,
W ₁₁ , W ₂₁ , and W ₃₁ represent the leading position in the traveling direction of the pattern A in each printing unit, and the positions away from W ₁₁ by l are sequentially designated as W ₁₂ , W ₁₃ , W ₁₄ , and W ₁₅ , respectively. L behind W ₂₁
The positions separated by W are sequentially set as W ₂₂ , W ₂₃ , W ₂₄ , W ₂₅ , and W _26, and the positions separated by 1 behind W ₃₁ are sequentially set as W ₃₂ ,
W ₃₃ , W ₃₄ , W ₃₅ , W ₃₆ , W ₃₇ .

First, in the state shown in FIG. 1A, in the printing unit 1U, the pattern A is printed between W _{11 and} W ₁₂ as shown in FIG. 2A. As shown in the printing unit 2U in FIG. 2 _{(b), W 21 ~W 22} , W 24 is the pattern A already printing unit 1U between to _W-25 is printed, the printing unit 1U and the printing unit pattern B is printed between W ₂₂ to _W-23 because the length of the path and 2U is set to l (3n-1). In the printing unit 3U, as shown in FIG. 2 (c), W _{31 to} W ₃₃ , W
Between Units _{34 and} W _36, the print units 1U and 2U have already been used to print patterns A and B.
Is printed, but printing unit 2U and printing unit 3U
Since the path lengths of and are set to l (3n-1),
The pattern C is printed between W _{33 and} W ₃₄ .

Then, in the state shown in FIG. 1B, in the printing unit 1U, the space between W _{12 and} W ₁₄ of the sheet W is changed to the printing unit 2U.
In between W ₂₃ to _W-25 is, during the printing unit 3U in W ₃₄ to _W-36 is sent without being printed. As described above, since the impression cylinder 10 and the elevating rolls 11 and 12 ascend and descend integrally,
Even in the state of FIG. 7B, the length of the path between the printing units does not change and is l (3n−1), and the sheet W can be sent by the length of 2l at the same speed as the peripheral speed of the gravure cylinder. Good.

This completes one cycle, and each printing unit returns to the state shown in FIG. In the next cycle, as shown in FIGS. 3 (a), (b), and (c), the printing unit 1U
Then, the pattern A is printed between the W _{14 and} W ₁₅ of the sheet W in the printing unit.
In 2U, the pattern B is between W _{25 and} W ₂₆ , and in printing unit 3U, it is W
Pattern C is printed between ₃₆ to _W-37. In this way, the patterns A, B and C are printed on the sheet W one after another at intervals of l.

In the above embodiment, since the patterns A, B, and C are printed at the same intervals as the circumference of the gravure thin lid, the path length of each printing unit is set to 1 (3n-1), and the impression cylinder 10 sets each Although the amount of the sheet W to be sent when it is separated from the gravure cylinder is 2 liters, if the patterns A, B and C are printed at arbitrary intervals other than the circumference of the gravure cylinder, the length of the path of each printing unit is set. 1 (3n-1) or the amount 21 of the sheet W to be fed when the impression cylinder 10 is separated from each gravure cylinder. That is, when changing the interval between the patterns printed by the same gravure cylinder, the amount of the sheet W is changed.
When 2l is changed to change the interval between the patterns printed on different gravure cylinders, the length l (3n-1) of the above path may be changed.

The number of printing units is not limited to three as in the above embodiment, and any number may be provided. However,
At this time, the path length of each printing unit is 1 (mn-1) where m is the number of printing units.

Further, although the seat W is run at a constant speed in the above embodiment, the running speed may be changed. FIG. 7 shows an example of changing the traveling speed of the seat W. In the figure, a drive roll 40 and a pressing roll 41 forming a pair of nip rolls are provided in front of the sheet W of the first printing unit 1U in the traveling direction, and the sheet W of the first printing unit 0U is provided.
A driving roll 50 and a pressing roll 51 forming another pair of nip rolls are provided on the discharge side. Drive roll 4
For example, 0 and 50 are connected to respective DC motors (not shown) so that the rotation speed can be changed independently. If the traveling speed of the sheet W can be changed in this way, it is not necessary to provide the raising and lowering rolls in front of and behind the impression cylinder 10 as shown in FIG. 1, but in the front and rear of the impression cylinder 30 shown in FIG. The rolled rolls 31, 32 may be fixed rolls.

Next, the operation of the drive rolls 40 and 50 shown in FIG. 7 will be described.

The drive rolls 40 and 50 rotate at the same peripheral speed as the gravure cylinder while the impression cylinder 30 is pressed against the gravure cylinder, and the rotation speed of the drive rolls 40 and 50 while the impression cylinder 30 is separated from the gravure cylinder. Shall be changed. First,
While the impression cylinder 30 is moving upward, the peripheral speed of the drive roll 40 is made slower than that of the gravure cylinder, and the peripheral speed of the drive roll 50 is made faster than that of the gravure cylinder. This causes the sheet W to be an impression cylinder.
Even if 30 rises, it can be separated from the gravure cylinder without sagging. When the rise of the impression cylinder 30 is completed, the drive rolls 40 and 50 are rotated at the same peripheral speed, and the sheet W is fed by a certain length. While the impression cylinder 30 is descending, the peripheral speed of the drive roll 40 is faster than the peripheral speed of the gravure cylinder, and the peripheral speed of the drive roll is slowed down so that the sheet W is not pulled.
By repeating the above operation, the pattern of each gravure cylinder is printed on the sheet W at a predetermined interval. Further, in this case, the feeding amount of the sheet W can be arbitrarily set while the impression cylinder 30 is away from the gravure cylinder, and the interval between the patterns printed by the same gravure cylinder can be arbitrarily changed.

In each of the above embodiments, the impression cylinder moves up and down to separate the sheet W from the gravure cylinder, but the pressure cylinder may be fixed and the gravure cylinder may be moved up and down.

(Effects of the Invention) As described above, in the present invention, the step of pressing the sheet onto the surface of the gravure cylinder that rotates with the impression cylinder, and the step of releasing the pressure of the impression cylinder so that the sheet does not contact the surface of the gravure cylinder Since printing is performed by alternately repeating the process of feeding the amount, it is possible to print the pattern on the gravure cylinder on the sheet surface at arbitrary intervals by minimizing the area where cells are not formed on the cylinder surface. As a result, the manufacturing cost of the grabber cylinder can be reduced, and the workability of exchanging the gravure cylinder can be improved in use.

In addition, a flat part with no narrow cells is provided on the surface of the gravure cylinder, so the border of the pattern can be neatly drawn out, and ink is not left unwound by the doctor on the part of the gravure cylinder surface where there are no cells. This brings about an effect that it is possible to perform printing without stains with the minimum amount.

[Brief description of drawings]

1 (a) and 1 (b) are explanatory views of a process showing one embodiment of the present invention, FIGS. 2 (a), 2 (b) and 2 (c), and FIGS. 3 (a) and 3 (b), (C) is an explanatory view of a state printed in the step shown in FIG. 1, FIGS. 4 (a) and 4 (b) are external views and sectional views of the gravure cylinder 1 shown in FIG. 1, and FIG. 5 (a). ) And (b) are external views and cross-sectional views of a conventional gravure cylinder, and FIG. 6 is an explanatory view showing an example in which the patterns printed by the gravure cylinders are printed at regular intervals without overlapping.
FIG. 7 is an explanatory view showing another mode of the step shown in FIG. 1, 2, 3 …… Gravure cylinder 4 …… Doctor 5 …… Ink pan 10 …… Impression cylinder 11, 12 …… Lifting roll 13 …… Dryer 14 …… Cooling roll 15 …… Compensator roll 20 …… Guide roll A, B, C ... Design W ... Sheet

Claims (1)

(57) [Claims] 1. A step of pressure-bonding continuously supplied sheets to the surface of a rotating gravure cylinder by means of an impression cylinder to transfer ink in cells on the gravure cylinder to the surface of the sheet, and pressure bonding of the pressure cylinder. In the gravure printing method of printing the pattern on the gravure cylinder on the surface of the sheet at an arbitrary interval by alternately repeating the step of releasing the sheet and sending a constant amount without contacting the gravure cylinder surface, A gravure printing method, characterized in that a flat portion having no narrow cells is provided on the surface of the gravure cylinder along the axial direction of the gravure cylinder.