JP2003072022A - Web-fed rotary gravure press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a web-fed rotary gravure press which can surely prevent fog independent of the skill of an operator and standardize work. SOLUTION: The press has a plate cylinder 11 for printing with ink adhered to a place face 11a, a doctor 14 for scraping off the excess ink adherent to the place face 11a, a plate cylinder driving part 13 for driving the plate cylinder 11, a target torque storage part 19a for storing the target torque of the driving part 13, a torque detection part 19 for detecting the torque of the driving part 13, and pushing pressure adjustment parts 16, 17, and 18 which adjust a pushing pressure to push the doctor 14 to the plate cylinder 11 when the torque detected by the detection part 19 is different from the target torque stored in the storage part 19a to make the torque agree with the target torque.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gravure printing machine for transferring an ink attached to an image area of a printing plate onto a printing object for printing.

[0002]

2. Description of the Related Art In a gravure printing machine, it is very important not to cause a so-called "fog" in which a white background portion or a thin pattern portion of an object to be printed is lightly soiled with ink.
This "fogging" occurs when the excess ink attached to the plate surface is not sufficiently scraped off, and the excess ink is transferred to the print target. In particular, it tends to occur when printing at high speed.

Therefore, conventionally, a printing press operator manually adjusts the air supplied to the air cylinder to press the doctor against the plate cylinder so that the excess ink adhering to the plate surface can be sufficiently scraped off. The pressure to operate (hereinafter referred to as "doctor pressure") was being increased.

[0004]

[Problems to be solved by the invention] However, "fog"
Does not occur when printing at low speed, and does not always occur even when printing at high speed, so it is easily overlooked by the printing press operator. Therefore, a large amount of defective printed matter may be printed before it is discovered. Also, if the doctor pressure is too high, (1) the doctor will bend and the doctor angle will change, resulting in poor print quality, (2) the doctor's blade edge will wear quickly, (3)
There is a problem that dust is easily accumulated. Therefore, adjustment to an appropriate value by a manual operation of the printing press operator is a highly difficult task, and the number of adjustment points is large in accordance with the number of multicolor printing plates, which imposes a heavy work load.

The object of the present invention is to reliably prevent fogging without depending on the skill of the operator.
It is to provide a gravure rotary press that enables standardization of work.

[0006]

The present invention solves the above-mentioned problems by the following means for solving the problems. It should be noted that, for ease of understanding, reference numerals corresponding to the embodiments of the present invention will be given and described, but the present invention is not limited thereto. In order to solve the above problems, the invention of claim 1 provides a printing plate (11
A plate cylinder (11) for applying ink to a) for printing, a doctor (14) for scraping off excess ink adhering to the plate surface (11a), and a plate cylinder drive unit for driving the plate cylinder (11). (13), a target torque storage section (19a) for storing the target torque of the plate cylinder drive section (13), and a torque detection section (19) for detecting the torque of the plate cylinder drive section (13).
When the torque detected by the torque detection unit (19) is different from the target torque stored in the target torque storage unit (19a), the doctor (14) is moved to the plate cylinder (1).
Pressing pressure adjusting unit (16, 17, 1) that adjusts the pressing pressure applied to 1) and makes the torque match the target torque.
8) and a gravure rotary press.

According to a second aspect of the present invention, in the gravure rotary press according to the first aspect, a target pressing pressure input section (15) for inputting a target pressing pressure for pressing the doctor (14) against the plate cylinder (11) is provided. The torque detector (19)
Detects the low-speed printing torque of the plate cylinder driving unit (13) during low-speed printing when the doctor (14) is pressed at the target pressing pressure, and the target torque storage unit (19) is detected.
(a) is a gravure rotary press characterized in that the low-speed printing torque is stored as a target torque.

The invention of claim 3 relates to claim 1 or claim 2.
The gravure rotary press according to claim 1, wherein the pressing pressure adjusting unit (16, 17, 18) keeps the pressing pressure of the doctor (14) constant while changing the printing speed. It is a turning point.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. Figure 1
FIG. 1 is a diagram showing an embodiment of a gravure rotary press according to the present invention. The gravure rotary press 10 includes a plate cylinder 11 and an impression cylinder 12.
Is a so-called sectional drive type gravure printing machine in which each plate cylinder 11 is driven by an individual plate cylinder drive motor 13. The gravure rotary press 10 includes a plate cylinder 11, an impression cylinder 12, and a plate cylinder drive motor 1.
3, doctor 14, doctor pressing force input device 1
5, an air cylinder air pressure calculator 16, an electropneumatic converter 17, an air cylinder 18, and a motor torque detector 19
And to print on a print target.

The plate cylinder 11 has ink adhered to the plate surface 11a, and is rotated by a plate cylinder drive motor 13.
The torque of the plate cylinder drive motor 13 is always detected by the motor torque detector 19. The impression cylinder 12 presses the printing target against the plate surface 11a. Doctor 14 is edition 11
The ink adhering to the non-image area (convex portion) of a is scraped off.
When the ink adheres to the plate surface 11a, the ink in the non-image area is scraped off by the doctor 14, and the ink remaining in the image area (recess) is transferred to the print target, thereby performing printing.

The doctor pressing pressure input device 15 is a device for inputting a target pressure when the doctor 14 is pressed against the plate cylinder 11. As described above, when the pressing pressure is insufficient, “fog” occurs, and when the pressing pressure is excessive, the doctor 14 bends and print quality deteriorates. Therefore, an appropriate pressure obtained in advance is input as the target pressure.

The air cylinder air pressure calculator 16 calculates the air pressure supplied to the air cylinder 18 in order to press the doctor 14 against the plate cylinder 11 with an appropriate doctor pressure, and outputs it as a voltage value.

The electropneumatic converter 17 adjusts the air pressure of the compressed air supplied to the air cylinder 18 based on the voltage output from the air cylinder air pressure calculator 16.

The air cylinder 18 sucks the compressed air whose air pressure is adjusted by the electropneumatic converter 17, and converts the air pressure into a force with which the doctor 14 presses the plate cylinder 11. The air cylinder 18 uses a transmission mechanism to make the doctor 1
4 are connected, and the doctor 14 is pressed against the plate cylinder 11 with a force corresponding to the air pressure.

The motor torque detector 19 is a detector for detecting the torque of the plate cylinder drive motor 13. First, the motor torque detector 19 detects the torque of the plate cylinder drive motor 13 when the doctor 14 is pressed against the plate cylinder 11 at a target pressure and the plate cylinder 11 is rotating at a low speed, and the torque value is targeted. The target torque storage unit 19a stores the torque value. After that, the motor torque detector 19 constantly detects the torque of the plate cylinder drive motor 13. The torque of the plate cylinder drive motor 13 varies depending on the size of the plate cylinder 11, but since the torque is detected by the motor torque detector 19, it can be accurately detected.

FIG. 2 is a diagram showing the relationship between the torque of the motor for driving the plate cylinder and the printing speed. 2A is a graph when the doctor pressure is constant regardless of the printing speed, and FIG. 2B is a graph when an appropriate doctor pressure is set according to the printing speed. 2 (A) and 2 (B)
In, the horizontal axis represents the printing speed (surface speed of the plate cylinder), and the vertical axis represents the motor torque. Further, of the components of the motor torque, those due to the transmission system are subtracted, and only those due to the doctor are extracted. According to this, when the doctor pressure is constant regardless of the printing speed, as shown in FIG. 2A, the torque of the plate cylinder drive motor 13 that drives the plate cylinder 11 increases as the printing speed increases. Decrease. On the other hand, when an appropriate doctor pressure is set according to the printing speed, as shown in FIG. 2B, the torque of the plate cylinder drive motor 13 that drives the plate cylinder 11 decreases even if the printing speed is high. It is constant without doing. On the contrary, the doctor pressure corresponding to the printing speed that keeps the torque of the plate cylinder drive motor 13 constant is an appropriate doctor pressure, and it can be set as the target doctor pressure.

The reason why the doctor pressure for keeping the torque of the plate cylinder drive motor 13 constant is the proper doctor pressure is as follows.
It can be thought of as follows. That is, as described above, when the printing speed of the gravure printing machine is increased, “fog” may occur, but the cause is
This is because the ink is not sufficiently scraped off on the surface of the plate surface 11a. When the ink is scraped off by the doctor 14, due to the viscosity of the ink, the ink on the surface of the plate surface 11 a pushes up the doctor 14, that is, acts as a force for generating a gap between the plate surface 11 a and the doctor 14. When the printing speed is increased, the force increases to widen the gap, and the amount of ink passing through the gap also increases to cause "fog".

By increasing the printing speed, the plate 1
The gap between 1a and the doctor 14 increases, and the ink existing in the gap has a lubricating effect. Therefore, by increasing the printing speed, the friction between the plate surface 11a and the doctor 14 decreases. Therefore, as shown in FIG. 2A, it is considered that the torque of the plate cylinder drive motor 13 that drives the plate cylinder 11 is reduced by increasing the printing speed.

On the other hand, when the proper doctor pressure is set according to the printing speed, the doctor pressure is increased when the printing speed is set high to prevent the gap from expanding.
Therefore, the increase in the amount of ink that passes through the gap is suppressed and "fog" does not occur. Further, since the ink having a lubricating action existing in the gap does not increase, it is considered that the torque of the plate cylinder drive motor 13 that drives the plate cylinder 11 does not decrease and is constant even when the printing speed is high.

FIG. 3 is a flow chart for explaining a target torque setting operation of the gravure rotary press. Doctor 14
When the target doctor pressure for pressing the plate cylinder 11 is input from the doctor pressing pressure input device 15 (step (hereinafter referred to as “S”) 101), the air cylinder air pressure calculator 16 supplies the air pressure to the air cylinder 18. Is calculated and output as a voltage value (S102). Then, the air pressure of the compressed air supplied to the air cylinder 18 is adjusted by the electropneumatic converter 17 (S103), the air pressure is changed, and the doctor 14 is pressed against the plate cylinder 11 at the target doctor pressure (S1).
04). Then, the rotation torque of the plate cylinder drive motor 13 that is printing at a low speed is detected by the motor torque detector 19 (S
105), and stores the rotation torque as a target torque (S106).

FIG. 4 is a flow chart for explaining the doctor pressure adjusting operation of the gravure rotary press. The motor torque detector 19 detects the rotation torque of the plate cylinder drive motor 13 (S201). Here, the detected torque is fluctuating (S202), and the printing speed is not being changed (S20).
3) The air cylinder air pressure calculator 16 calculates the air pressure to be supplied to the air cylinder 18, and outputs it as a voltage value (S204). If the printing speed is being changed in S203, disturbances other than changes in the ink flow rate act, so the process returns to S201 while maintaining a constant doctor pressure without changing the doctor pressure.

Subsequently, the electropneumatic converter 17 adjusts the air pressure of the compressed air supplied to the air cylinder 18 (S20).
5) After pressing the doctor 14 against the plate cylinder 11 while adjusting the doctor pressure by changing the air pressure (S20).
6) Then, the process returns to S201 again, and the above control is repeated.

During the printing operation, the doctor pressure, the finisher pressure, the printing pressure, the inter-unit tension, etc. may be changed. In this case, the torque increase / decrease of the plate cylinder drive motor 13 that occurs when each setting is changed is detected by the motor torque detector 19, and the torque increase / decrease is increased / decreased to the initially stored torque value.

Further, the method of controlling the doctor pressure so that the torque of the plate cylinder drive motor 13 is made constant according to the change of the printing speed has been described, but the load applied to the plate cylinder drive motor 13 is only the doctor pressure. But other than that,
There are also the finisher pressure, printing pressure, tension between units, etc. Therefore, originally, it is necessary to control not only the doctor pressure but each of these. However, since the other components have a small torque increase / decrease amount when the printing speed is changed, only the doctor pressure is focused. If the influence other than the doctor pressure component is large,
In order to extract only the doctor pressure component, components other than the doctor pressure may be investigated in advance and calculated.

According to this embodiment, the plate cylinder drive motor 13
The torque of the plate cylinder drive motor 13 is made to coincide with the target torque by adjusting the doctor pressure of the doctor 14 when the torque is different from the target torque. Therefore, it is possible to prevent the gap between the plate surface 11a and the doctor 14 from expanding. The amount of ink that passes through the gap is also suppressed and "fog" does not occur. This makes it possible to standardize work and prevent "fog". Further, since the target pressing pressure for pressing the doctor 14 against the plate cylinder 11 is input, a predetermined pressing pressure may be input regardless of the size of the plate cylinder 11. Further, when the printing speed is increased or decreased, the pressing pressure of the doctor 14 is not changed, so that it is not affected by the disturbance.

(Modifications) The present invention is not limited to the above-described embodiments, but various modifications and changes can be made, which are also within the scope of the present invention. For example, in the above embodiment, the type having two printing units has been described, but the number is arbitrary. Further, the size of the plate cylinder 11 is arbitrary and may be changed for each printing unit. For example,
Only the final version may be a large version.

[0027]

As described in detail above, according to the first aspect of the invention, when the torque detected by the torque detecting portion is different from the target torque, the pressing pressure for pressing the doctor is adjusted to adjust the torque. Since it matches the target torque, it is possible to suppress widening of the gap between the printing plate and the doctor, and to prevent "fog".

According to the second aspect of the present invention, since the target pressing pressure for pressing the doctor against the plate cylinder is input, a predetermined pressing pressure may be input regardless of the size of the plate cylinder.

According to the third aspect of the present invention, the pressing pressure adjusting unit keeps the pressing pressure of the doctor constant during the change of the printing speed, so that the influence of disturbance can be avoided.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a gravure rotary press according to the present invention.

FIG. 2 is a diagram showing a relationship between a torque of a motor driving a plate cylinder and a printing speed.

FIG. 3 is a flowchart illustrating a target torque setting operation of the gravure rotary press.

FIG. 4 is a flowchart illustrating a doctor pressure adjusting operation of the gravure rotary press.

[Explanation of symbols]

10 Gravure rotary press 11 plate cylinder 11a Plate 12 impression cylinder 13 Plate cylinder drive motor 14 Doctor 15 Doctor pressing force input device 16 Air cylinder air pressure calculator 17 Electro-pneumatic converter 18 Air cylinder 19 Motor torque detector 19a Target torque storage unit

Claims (3)

[Claims] 1. A plate cylinder for depositing ink on a plate surface for printing, a doctor for scraping off excess ink adhering to the plate surface, a plate cylinder drive unit for driving the plate cylinder, and a plate cylinder drive unit. When the target torque storage unit that stores the target torque, the torque detection unit that detects the torque of the plate cylinder drive unit, and the torque detected by the torque detection unit are different from the target torque stored in the target torque storage unit, A gravure rotary press including: a pressing pressure adjusting unit that adjusts a pressing pressure for pressing the doctor against the plate cylinder and matches the torque with a target torque. 2. The gravure rotary press according to claim 1, further comprising a target pressing pressure input section for inputting a target pressing pressure for pressing the doctor against the plate cylinder, wherein the torque detecting section is configured such that the doctor presses the target pressing pressure. A gravure rotary press characterized in that a low-speed printing torque of the plate cylinder driving unit that is pressed at a low speed and is printing at a low speed is detected, and the target torque storage unit stores the low-speed printing torque as a target torque. 3. The gravure rotary press according to claim 1, wherein the pressing pressure adjusting unit holds the pressing pressure of the doctor constant while the printing speed is changed. Gravure rotary press.