JPS63159055A - Color-to-color registering apparatus in flexographic rotary press - Google Patents

Abstract

PURPOSE:To enhance reliability by reducing the number of mechanical drive component parts, by detecting the shift quantity and direction of a printing position at every one or more times of printing by a sensor and controlling the rotational speed of the plate cylinder positioned in the next process to align a phase. CONSTITUTION:The roll-shaped sheet 2 mounted on an unwinder 1 by a shaft is unwound while grasped at the part of rotating pull rolls 3 to pass through a plurality of printing units 4 and receives printing between plate cylinders 6 and an impression rolls 7 to be taken up by a winder 8. Herein, the printing positions of the first and second printing units 4 are detected by sensors 18 and plate cylinder part rotary driving control mechanisms 23 calculate the shift quantity and direction of printing at every one or more time of printing on the basis of the signals of said sensors 18 and the rotational speeds of the motors 22 of the plate cylinders 6 in the printing units 14 of the next process, that is, the phases of the plate cylinders 6 to perform the registering between colors. By this constitution, the number of mechanical drive parts in the movement of the printing units are reduced and the lowering in accuracy due to abrasion is reduced and the reliability of durability and reproducibility is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color-to-color registration device in a flexographic rotary printing press having an intermittent feeding device for continuous sheets.

[Conventional technology]

Figure 5 shows a conventional continuous sheet intermittent flexo rotary printing machine, where (5-I!L) is an overall schematic diagram and (5-I!L) is an overall schematic diagram;
11) is a configuration diagram of the printing section. FIG. 6 is a functional explanatory diagram of a printing position detection sensor which is a critical element of the color registration device.

FIG. 7 is an explanatory reference diagram of the color-to-color registration method, showing the state of the printing surface in the printing section, pull roll section, and sheet. To explain the overall structure, Figure 5 (5-a
As shown in ), the rolled sheet 2 whose center is suspended by the unwinding machine 1 is pulled by the rotation of the pull roll 3, so it rotates in the direction of the arrow, is rewound, and is sent to the printing section unit 4. It gets sucked in. The rewound sheet 5 passes between the printing unit 40, the plate cylinder 6 and the impression cylinder 7, and is printed.
Further, the printed sheet 5 is wound up again into a rolled sheet 9 by a winding machine 8.

The printing section unit 4 will be explained as shown in FIG.
), ink 11 in the ink reservoir 10 is transferred to the printing plate 13 on the plate cylinder 6 by the inking roll 12. Further, excess ink on the surface of the inking roll 12 is scraped off by the doctor blade 14 and flows back into the ink reservoir 10. Reference numeral 7 in FIG. 5 (5-1) is an impression cylinder that presses the continuous sheet 5 against the printing plate 13. These constitute the printing section unit 4, and the continuous sheet 5 is printed by passing between the printing plate 13 and the impression cylinder 7 of the printing cylinder 6 of the printing section unit 4 and coming into contact with the printing plate 13. It is done. Generally, printing is performed in three to six colors, and a corresponding number of printing unit units 4 are required. This figure shows an example in which three sets of three-color printing sheets, spools, and units 4 are installed. The running speed of the sheet 5 is adjusted so that the surface color of the printing plate 130 matches the pull roll 3, impression cylinder 7, and printing plate 1.
The outer peripheral speeds of No. 3 are controlled to match. The rewinding machine 1 is equipped with a brake device (not shown) for the roll 2 so that the sheet 5 does not become sagging due to unwinding of more sheets than necessary due to the inertia of the roll. Also, the winder 8
is equipped with a drive device (not shown) for a roll 9 for winding up the sheet 5 that is fed along the pull court 3.

The printing length in such a rotary printing press is equal to or less than the circumferential length of the outer diameter of the printing plate (Lo-π·D). The length of repeated printing is determined by the arc length of the outer circumference of the printing plate, but if this length is smaller than the outer circumference length (π·D), unprinted margins will occur when the sheet is continuously fed. The intermittent feed device was developed to reduce such blank (unnecessary) portions, and various methods have been proposed.

The fiftieth method is a folding method, in which the tensile member 15 of the sheet 5 is attached to one side of the pull roll 3, and its surface speed is made to match the surface color of the printing plate 130 (i.e., the pull roll 3 and the printing plate 130 are The outer diameter is the same and they rotate synchronously.) Furthermore, the arc length dimension of the tension member 15! This is a rotary printing press using an intermittent sheet feeding method in which the printing plate 13 has an arc length of 12 or more.

According to this method, sheet 5 is generated every 3.1 rotations of the pull roll! 1 is pulled and that white print is! It is 2. Therefore, 1o-11-12 is the theoretical margin length IQ, and the arc length dimension J of the tension member 15, t-
By changing this, you can freely set the dimension 1o required as a margin.

The printing section unit 4 has a unit moving pinion 16 installed at the lower end, and is moved in the sheet traveling direction by a unit moving device that rolls on a rack 17 fixed to a surface plate by a pinion drive motor (not shown). It is configured so that it can move back and forth by a certain amount. In addition,
Distance between printing units 4 (distance between plate cylinders 6 axes XL1-L2
) is set equal to the tension member arc length dimension 11 as an initial condition.

Next, the intermittent feeding device will be explained. With respect to the pull roll 3 configured as described above and rotating at a constant speed, the sheet 5 runs at a speed consistent with the surface speed of the pull roll 3 only while the tension member 15 of the pull roll 3 is holding the sheet 5; (During this period, the printing plate 13 is rotating synchronously with the pull roll 3.
The necessary printing is done by ) When the tension member 15 does not clamp the seat 5, the seat 5 stops traveling due to a brake device (not shown) applied to the seat 5.

Seat 5 travels depending on the settings of the pull meal section.
Due to the intermittent motion with repeated stops, the effective usable area of the seat has expanded.

However, such intermittent sheet rotary printing machines have the following problems.

That is, in this method, a stopped sheet 5t'' is held by a tension member 15 wound around a pull roll 3 rotating at a constant speed, and the sheet 5 is instantly accelerated. Also, since the sheet 5'Ik accelerates instantaneously, a large tensile force acts on the sheet 5 during acceleration, causing elongation, vibration, meandering, etc. of the paper. The same holds true when stopping the motor, and this situation is repeated every cycle.

Therefore, with rotary printing presses using the intermittent feed method, it is not possible to obtain highly accurate repeat feed lengths, especially at high speeds.
Printing accuracy is greatly reduced due to the occurrence of misregistration between colors.

In order to solve the above-mentioned problems, various countermeasures have been proposed so far. The most advanced method will be explained below.

As for the structure, as shown in FIG. 5 (5-a), a sensor 18 is installed between the printing units 4 to detect the actual printing position after passing through the pre-processing unit 4. It identifies the shade of color on the surface and detects its position.As shown in Figure 6, the printed mark 19 within the field of view of the sensor 18 can be converted into a digital signal and its position can be measured. It looks like this. The sensor 18
The deviation between the original theoretical printing position and the actual printing position is measured for each printing or multiple printings, and at the same time, the difference between the printing of the previous color and the printing of the next color is determined according to the amount and direction of the deviation. The position of the next unit 4 is moved (finely adjusted) and corrected so that the relative position is normal. By performing this control between all printing units 4, the accuracy of color registration can be improved.

The effect is explained as follows.

FIG. 7 shows the state of the printing surfaces of the printing section unit 4, pull roll section 3, and sheet 5.

This figure shows the state immediately after the intermittent running has stopped, printing with the small print plate 13 has been completed, and the tension member 15 has released the sheet 5.
The pull roll 3rd plate cylinder 6, etc. continues to rotate, but the sheet 5
The vehicle is completely stopped.

To explain the printing surface 20 immediately after passing the first color in the figure, the Al point is the regular printing position of the first color, and is located at a distance of d1 from the center point 01 of the first color printing unit 4. However, the actual printing of the first color was A1 point (01 point, bct
distance i). If the printed surface is sent to the second color printing unit 4 in this state and the second color is printed in the same way, the color registration between the first and second colors will be d'1.
A deviation of -dl-Δd□ will occur. In order to prevent this, the distance (Ll-d'l) from the current point A'1 to the center point 02 of the second color printing unit must be set to the normal distance (Lt
dt) is a storm, that is, (Lx (b
) -(Ll-d'1) "d'1(h-Δd1 step, move the second color printing unit 4 by Δdl in the direction of the third color.

Similarly, to describe the printing surface 21 immediately after passing through the second color, point A2 is at a distance of dl from point ol, the center of the first color printing unit 4, which is the regular printing position for the second color. However, assuming that the actual printing of the second color becomes a point A/ (distance from the 01 point to fid/) due to an error such as the sheet intermittent feed length, then in the following case, align the color registration between the first and third colors. For this purpose, the distance (L1+L2)-dl2 from point A'2 to point 03, the center of the third color unit, is the regular compression L1+
L2)-dl is sufficient.

That is, ((Ll +L2)-dl)-((Ll
+L2) -d'z)-dl2-dl--Δd2 The third color printing unit 4 is moved toward the second color by Δd2.

The printing position is measured by a sensor 18, and the unit 4 position is adjusted by a unit moving device comprising a rack 17, a pinion 16, a pinion drive motor, and the like. In this way, the deviation and direction of the printing position are measured every time printing is performed or every time printing is performed, and the printing unit 4 located in the next process is moved to correct the printing deviation. The printing unit 4 always moves while sheet 5 is stopped (sheet 5 and printing plate 1).
3 must be done in a non-contact state).

Furthermore, it must be kept in mind that once a unit moves (4t), the distance between the units will change the next time the unit moves. That is, the next unit movement amount must be determined based on the previously set position that has changed, and the sequence inevitably becomes complicated.

[Problem that the invention seeks to solve]

In rotary printing machines that use continuous sheets and are equipped with a device that feeds the sheets intermittently, poor reproducibility (sheet feed Variation in length) is an unavoidable drawback,
Due to this, improving the color registration accuracy of printing has been a major issue in improving printing quality.

Conventionally, (1) a method of detecting the difference in sheet running amount between the pull roll and the printing unit and correcting it on the average.

(2) Alternatively, as described in the previous section, after passing through the printing unit (after printing is completed), the sensor measures the deviation between the original printing position and the actual printing position, and at the same time, adjusts the amount and direction of the deviation. A method has been proposed in which the position of the next unit is moved so that the relative position between printing of the previous color and printing of the next color becomes normal. However, the above-mentioned (13) is not reliable in terms of accuracy, and the unit movement method of the above-mentioned (2) is a mechanically complex device that is difficult to control, and the setting position accuracy is also low. , the mechanical accuracy and assembly accuracy of parts such as pinions have a large effect, and the wear of these transfer devices has a direct effect on the decrease in position accuracy. This method has many problems, such as the accuracy of color registration and the durability of maintaining this accuracy.

[Means for solving the problem J: A sensor is installed after each printing unit to detect the actual printing position after passing through that unit, and this sensor detects the original theoretical position after each printing or multiple printings. The deviation between the printing position and the actual printing position is measured, and at the same time, the next unit is adjusted according to the amount and direction of the deviation so that the relative position between the printing of the previous color and the printing of the next color is correct. Feedback control of the phase of the plate cylinder (printing plate).

In other words, if the sheet running state deviates backwards in the direction of travel, the phase of the plate cylinder is shifted backward, and if it deviates conversely, the phase is shifted forward to adjust the printing plate and sheet printing surface. To ensure that the printing reference points of each color match.

[Effect]

A sensor installed after each printing unit) detects the actual printing position after passing through the unit, and directly transmits the sheet running state (amount and direction of printing misalignment) measured by the sensor to the next process printing unit. Controls the phase of the plate cylinder.

Therefore, the correction accuracy is close to the driving accuracy of the motor, and highly accurate color registration is possible.

〔Example〕

FIG. 1 is an overall schematic diagram of a continuous sheet intermittent feed 7 lexo rotary printing machine embodying the present invention. FIG. 2 is an explanatory reference diagram of the color registration method, and shows the state of the printing surface in the printing section, pull roll section, and sheet.

FIG. 3 is an explanatory diagram showing the relationship between the printing section and the printing surface of the sheet in FIG. 2.

FIG. 4 is an explanatory diagram of the behavior of the outer periphery of the printing plate.

As shown in FIG. 1, the overall configuration is the same as that of the prior art described above, except for the plate barrel rotation drive control mechanism. The sheet is rewound by the nipping rotation in the rotation, passes through the printing section unit 4, is printed by a known method, and is wound up again into a rolled sheet 9 by the winder 8. 1 in the diagram
8 is a sensor that detects the printing position, and the function is the 6th sensor.
As shown in the figure, it is the same as that described in the conventional example.

Now, the feature of the present invention is that each printing unit 4 is provided with an independent motor 22 and plate cylinder rotation drive control mechanism 23, and the amount and direction of printing deviation measured by the sensor 18 are transferred to the printing unit unit 4 of the next process. The main point is that the motor 22 of the plate cylinder 6 is feedback-controlled and corrected.

The setting position and spacing of the printing unit 4 are the arc length dimensions of the printing plate 13! 2. Tension member 1 wound around pull roll 3 corresponding to
It is necessary to determine this along with the arc length dimension 11 of No. 5, and a known unit moving device is provided for setting the initial conditions. However, there is no need to adjust the movement after that, and all units 4 are fixed to the frame to prevent them from moving accidentally during printing! (not shown) is provided. In addition, a control device is also provided which receives signals from the sensor 18 and fully automatically controls the rotational speed of the plate cylinder phase control motor 22 of the printing unit. The position of the sensor 18 is set in advance before the start of operation so that the center of the sensor field of view and the regular position of the printing mark 19 match, and the distance between the installations of each printing unit 4 is set to the outer circumference of the tension member 15. arc length 11
The settings are completely compatible with the above.

Based on the above initial conditions, the operation will be explained next.

FIG. 2 shows the state of the printing surfaces of the printing unit 4, the three pull rolls, and the sheet 5. This figure shows the tension member 15 immediately after the intermittent running has stopped, and the printing by the pick plate 13 has been completed.
This is immediately after the sheet is released, and the pull roll third plate cylinder 6 and the like continue to rotate, but the sheet 5 has stopped running.

Sheet printing surface 20 immediately after passing the first color in the same figure
To explain, point Al is the regular printing position of the first color, and point C (h
at a distance of However, it is assumed that the actual printing of the first color is at point At (distance d'1 from point 01) due to an error such as the intermittent feed length of the sheet. If the printing surface is sent to the second color printing unit in this state and the second color is printed in the same way, the color registration between the first and second colors will be d'1.
A deviation of -dl-Δd1 will occur. (This Δdl
, as shown in FIG. 3 (3-b), has been moved an excessive amount p from the normal position. ) In order to correct this, the rotational speed of the second color plate cylinder 6 may be increased to advance the plate cylinder phase and start printing earlier. As shown in Fig. 4, originally the outer circumferential speed of the printing plate 13 should be adjusted to the sheet traveling timing from Al to 02, but by adjusting it to the sheet traveling timing from A'l to 02. 2
It is possible to match the printing color to the first color. Similarly, when looking at the sheet printing surface 21 that has passed the second color, point A2 is the regular printing position of the second color (distance A11 from 02 to side d2) A/, and point is the actual printing position of the second color ( 02
If the color is sent to the printing section unit 4 for the third color without correction, the color registration between the second and third colors will differ by d'2 - d2 - - Δd2. Become.

(This -Δd2 is due to underfeeding from the normal position as shown in Figure 3 (3-a).) To correct this, reduce the rotation speed of the third color plate cylinder, etc. , the plate cylinder phase may be delayed to delay the start of printing.

As shown in Figure 4, the sheet running timing should be adjusted to reach the printing plate outer circumferential speed from t-A2 to 03. Printing can match the second color.

In this way, the present invention detects the printing state (deviation amount, direction) and controls the motor 22 of the plate cylinder 6 of the printing section unit 4 in the next process.
The phase of the printing cylinder 6 is changed by controlling the rotational speed of the printing cylinder 6 through feedback control, thereby achieving registration between colors in printing.

The above operations are automatically controlled for each print or multiple prints, and as a result, it is possible to always maintain high precision color registration even if the dimensions of repeated paper feeds due to intermittent feeds are not constant. That is.

[Effects of the Invention] The color registration device according to the present invention has the ability to reduce color registration errors in printing due to variations in paper feed length by repeatedly feeding paper intermittently. A sensor detects the deviation amount and direction of the printing position every time or every multiple times, and controls the phase of the plate cylinder, such as controlling the rotation speed of the plate cylinder located in the next process, depending on the deviation amount and direction. By performing color registration, there are fewer mechanically driven parts such as the movement of the printing unit, which is a problem with conventional methods. reliability can be improved.

In addition, by providing each printing unit with an independent drive means (motor) for the plate cylinder, impression cylinder, etc., it is possible to correct misalignment for each unit, and electrical control can be performed independently, which simplifies the process. In addition, related work such as maintenance, inspection, and repair becomes easier.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram of a continuous sheet intermittent flexo rotary printing machine embodying the present invention. FIG. 2 is an explanatory reference diagram of the color registration method, and shows the state of the printing surface in the printing section, pull roll section, and sheet. FIG. 3 is an explanatory diagram showing the relationship between the printing section and the printing surface of the sheet in FIG. 2. FIG. 4 is an explanatory diagram of the behavior of the outer periphery of the printing plate. Figure 5 shows a conventional continuous sheet intermittent 9 flexo rotary printing machine (5-a
) is an overall schematic diagram, (5-1 is a configuration diagram of the printing section. Figure 6 is a functional explanatory diagram of a printing position detection sensor that is a component of the color registration device. Figure 7 is a diagram of the color registration system. A reference diagram explaining the method shows the printing section, pull roll section, and the state of the printing surface on the sheet. 1... Rewinding machine 3... Pull roll 4
...Print unit 5...Continuous sheet 6.
・Print cylinder 7 ・Impression cylinder 8 ・Take-up machine 13 ・
...Print plate 15...Tensile member 18...Sensor 2
2... Drive motor 23... Plate cylinder rotation drive control mechanism Sub-agent Patent attorney Shige Okamoto 2 other people

Claims (1)

[Claims] In a flexo rotary printing press that uses continuous sheets and has an intermittent feed device that intermittently feeds only the minimum amount of sheets according to the required amount of printing, each printing department unit installed in parallel has an independent system. A sensor installed corresponding to the printing section unit detects the amount and direction of the printing position deviation each time printing is performed, and the corresponding driving device performs feedback control. A flexo rotary press characterized in that the phase of the plate cylinder is changed and adjusted by changing the rotational speed of the plate cylinder during operation, depending on the situation, and the registration between colors in printing is automatically performed. Color registration device in .