JP2808458B2 - Fountain solution regulator for lithographic printing press - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an apparatus applied for controlling dampening water supply of a lithographic printing press.

[Conventional technology]

In a conventional lithographic printing machine, as shown in FIG. 5, the ink 6 transported from the ink source roller 4 through the ink mixing roller group 5 is transferred to the plate surface 11 by the respective rollers of ink forming rollers 7, 8, 9, and 10. Are supplied to the image portion of the image. The ink in the image area is transferred to paper through the rubber blanket 12 to form an image. On the other hand, the dampening water 14 passes through the water source roller 15 and forms a water film on the non-image area of the plate surface by the dampening roller 17,
Prevents ink from adhering to non-image areas.

In lithographic printing, the balance between the amount of ink and the amount of dampening water has a great effect on print quality. In particular, it is important to keep the amount of dampening water optimal. At present, this water control depends on the intuition of the operator.

[Problems to be solved by the invention]

The above-mentioned optimum necessary dampening water amount largely varies depending on not only the ink amount but also the machine speed and the surrounding temperature and humidity.

For this reason, if the operator neglected to check the printed matter, a printing failure such as a so-called stain or water mark would occur, resulting in waste paper. As this ratio increases, the printing cost increases.

Further, the operator needs to always check the printed matter and adjust the dampening solution amount, which causes a disadvantage that the operator cannot leave the printing machine.

[Means for solving the problem]

The state of mixing of ink and water on the inking roller, ie, the state of emulsification, is most likely to fluctuate and has a large effect on print quality.

In the present invention, a roller is installed adjacent to the ink forming roller, and a device for detecting the state of ink adhesion on this roller, that is, an ink concentration is installed. Then, the dampening water supply device is adjusted so that the detection signal from the detection device matches the target value. That is, according to the present invention, a roller whose surface layer is made of a material having a high hydrophilicity is provided at a position adjacent to any one of the ink forming rollers, and the roller can be driven in the width direction on the roller to detect the ink density. A detector is fixed at a position where the ink density is the highest in the width direction of the roller, a detection signal of the ink density is received at this position, and this signal is compared / calculated with a target value. A damping solution for a lithographic printing press, wherein the control signal is supplied to the fountain roller, and the driving of the fountain roller is controlled so that the detected value falls within the range of the target value, and the dampening solution supply amount is adjusted. An adjustment device is provided.

[Action]

Since the surface layer of the roller provided adjacent to the ink forming roller is hydrophilic, the amount of ink adhering to the roller, that is, the ink concentration on the roller changes depending on the emulsified state of the ink and the dampening solution. If the dampening water supply is low,
Since the water content in the ink is small, the amount of ink adhered to the roller increases, and the ink density increases. On the other hand, as the fountain solution supply amount is increased, the water content in the ink increases, and as a result, water impedes the adhesion of the ink to the roller surface, so that the ink concentration on the monitor roller decreases.

As described above, according to the present invention, the ink density on the roller is detected by the detector, and the detected density is compared with the target value so as to be optimal, and calculated, and the target value is adjusted so as to coincide with the optimal emulsified state. Since the dampening water supply device is controlled so as to fall within the range, the optimum dampening water supply amount can be automatically maintained without the supervision of the operator.

〔Example〕

FIG. 1 is a diagram showing the overall configuration of an embodiment of a dampening solution adjusting device for a lithographic printing press according to the present invention. A new configuration is different from the conventional configuration in that a monitor roller 1, a detector (densitometer) 2 and a control device 3 are installed in a sheet-fed printing press, and the speed of a water supply roller 15 is controlled by a motor 16 so that the amount of water is reduced. This enables automatic control.

In this example, adjacent to the final inking roller 7,
The monitor roller 1 whose surface layer is made of a material having a high hydrophilicity is provided. As a method for imparting hydrophilicity to the surface layer of the monitor roller 1, there is, for example, a method of applying chrome plating under the following conditions. That is, as a bath type, a surge bath; a bath temperature is 10 to 25 ° C .; and a current density is 30 to 50 A / dm.
² ; The surface length of the monitor roller 1 is the same as that of the ink application roller 7. A densitometer 2 is installed to measure the ink density on the surface of the monitor roller 1. The densitometer 2 is movable in the width direction. First, immediately after printing is started, the densitometer 2 is scanned in the width direction by a command from the control device 3 to obtain the ink density distribution in the width direction on the monitor roller 1. Based on the density distribution, the densitometer 2 is moved to the position where the ink density is highest, that is, the position where the amount of water is the shortest. Then, an ink density detection signal at that position is sent to the control device 3 every moment.

The control device 3 compares the sent detection density with the ink density in the optimum range shown in FIG. 2, that is, the target density, and calculates a control signal for matching the detected density with the target density. A motor 16 for driving a water source roller 15 with a signal
Send to

As a result, the water supply roller 15 increases or decreases its rotation speed, thereby maintaining the dampening water supply amount optimally. The above control will be specifically described with reference to an internal configuration diagram of the control device 3 in FIG. 3 and a flowchart of control performed by the control device 3 in FIG. In FIG. 3, the motor 16 for driving the detector 2 is driven based on a command from the control / arithmetic unit 20. The detection signal from the detector 2 is sent to a signal converter 24 where the signal is converted and stored in the ink density distribution memory 22. The ink density / contrast target range memory 21 previously stores a preferable pattern of the ink density distribution and relative contrast on the monitor roller 1 as shown in FIG. 2, and further sets an optimum target range of the pattern. And memorize it.

The control / arithmetic unit 20 is configured to comprehensively control these. Next, a flowchart of control performed by the control / calculation unit 20 in such a configuration will be described with reference to FIG. In step S1, after the start, first, the past storage contents stored in the ink density distribution memory 22 are cleared, and step S2
The detector 2 is driven at a constant speed from one end to the other end on the monitor roller 1. In step S3, the signal driven by step S2 and detected by the detector 2 is fetched over the entire width of the monitor roller 1 and stored in the ink density distribution memory 22.

Next, in step S4, the data fetched and stored in step S3 is taken out from the ink density distribution memory 22, and a value (M) at which the density of the data becomes maximum is selected, and the width direction corresponding to the value of M is selected. (L) is obtained. In step S5, a command to drive the detector drive motor 16 to move the detector 2 to the position (L) obtained in step S4 is given.
Next, in step S6, the signal from the detector stopped at this position is constantly taken in, the signal of the pattern stored in advance from the ink density / contrast target range memory 21 is also taken in, and compared with the target value density. Check whether the result of the comparison operation is within the range of the target concentration, and if it is within the range, continue the operation as it is. If it is out of the range, you can select whether the concentration is too high or too low next. .
If it is too dark, a command is issued to the water roller drive motor control unit 23 in order to speed up the water roller 15 in step S8. If it is too thin, a water roller deceleration command is issued in step S7. If the control returns the concentration to within the range, the signal is continuously taken from the detector 2 and monitored.

By such control, the dampening solution supply amount can be kept optimal.

〔The invention's effect〕

According to the fountain solution adjusting device for a lithographic printing press of the present invention, the supply amount of the fountain solution is adjusted so as to constantly maintain the ink concentration on the monitor roller in the optimum range, so that good tone reproduction is always achieved. As a result, the number of waste sheets is reduced, and it is not necessary for the operator to constantly monitor the paper surface as in the past, so that a large rationalization is possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing the entire configuration of a dampening solution adjusting device for a lithographic printing press according to an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between the ink density on a monitor roller used in this embodiment and the relative contrast. FIG. 3 is an internal configuration diagram of the control device in the embodiment of FIG. 1, FIG. 4 is a control flowchart of the embodiment,
FIG. 5 is an overall configuration diagram of a conventional lithographic printing press. 1 ... monitor roller, 2 ... detector, 3 ... control device.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-170345 (JP, A) JP-A 64-44122 (JP, U) JP-B-60-5472 (JP, B2) (58) Field (Int.Cl. ⁶ , DB name) B41F 7/24-7/40 B41F 31/02

Claims (1)

(57) [Claims] A roller having a surface layer made of a material having a high hydrophilicity is provided at a position adjacent to any one of the ink forming rollers.
A detector which can be driven in the width direction on the roller to detect the ink density is provided. The detector is fixed at a position where the ink density is highest in the width direction of the roller, and a detection signal of the ink density is received at this position. , Which is compared and calculated with a target value, and gives a control signal to a fountain roller of the dampening water supply device, and controls the driving of the fountain roller so that the detected value falls within the target value range.
A dampening water adjusting device for a lithographic printing press, wherein a dampening water supply amount is adjusted.