JPH05162289A - Controller for film thickness - Google Patents

Abstract

PURPOSE:To keep life of a piezoelectric actuator long by a method wherein a film thickness control blade of a film thickness controller is stably operated with the piezoelectric actuator. CONSTITUTION:A film thickness control blade 2 is arranged by being opposed to a circumferential surface of a rotary roller l, and a tip of an output shaft 10 of a displacement generator 50 is made to abut against a rear surface near its tip. In the displacement generator 50, a piezoelectric actuator 7 is provided normally to an inner wall 6a of a box like casing 6, and a movable block 8 equipped with the output shaft 10 is fixed to its tip. A compression spring 9 is provided between the movable block 8 and an inner wall 6b of the casing 6, and the output shaft 10 is provided to an opposed side of the compression spring 9 of the movable block 8. The output shaft 10 presses the film thickness control blade 2 by elastic force of the compression spring 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film thickness control device.
Specifically, the present invention relates to a film thickness control device that controls the film thickness of a fluid supplied to the outer peripheral surface of a rotating roller by a piezoelectric element.

[0002]

2. Description of the Related Art In a printing press such as an offset rotary printing press, a film thickness control device for controlling an ink film thickness is used in order to obtain a printed matter without uneven printing.

As such a film thickness control device, Japanese Patent Laid-Open No. 2-29337, Japanese Patent Laid-Open No. 63-3955,
Japanese Utility Model Publication No. 2-104874 and Japanese Utility Model Publication No. 1631
There is one disclosed in Japanese Patent No. 33.

A typical structure of the conventional film thickness control device 70 disclosed in these publications is shown in FIG. In this film thickness control device 70, the base end of the film thickness control blade 2 made of an elastic plate such as a metal plate is fixed to the support 3, and the tip of the film thickness control blade 2 is a rotating roller. 1 is facing the outer peripheral surface. Then, when the ink 5 is stored in the ink pot 4a formed by the outer peripheral surface of the rotating roller 1, the film thickness control blade 2 and the side plate 4, and the rotating roller 1 is rotated in the direction of arrow A, the ink 5 is generated. It is supplied to the outer peripheral surface of the rotating roller 1 with a film thickness according to the gap g between the rotating roller 1 and the film thickness control blade 2.

The film thickness control blade 2 is driven by expansion and contraction of the piezoelectric element 7, and the piezoelectric element 7 is expanded to push the tip of the film thickness control blade 2 toward the rotary roller 1 side. The film thickness of the ink 5 can be reduced by narrowing the gap g between the film thickness control blade 2 and the film thickness control blade 2. Further, when the piezoelectric element 7 is contracted to separate the tip of the film thickness control blade 2 from the rotating roller 1, the gap g is widened and the film thickness of the ink 5 is increased.

[0006]

In the film thickness control device 70 as described above, since the film thickness of the ink 5 is controlled by the thick film control blade 2, the film thickness control blade 2 receives a reaction force from the ink 5. Receive F. The reaction force F is determined by the rotation speed N of the rotating roller 1, the gap g, and the viscosity coefficient η of the ink 5. The smaller the gap amount g, the larger the reaction force F received by the film thickness control blade 2.

On the other hand, the thrust characteristic of the piezoelectric actuator 7 is shown in FIG. The thrust F _p of the piezoelectric actuator 7 is
As the displacement amount (extension amount) L increases, it decreases, and when the displacement amount L is maximum, the thrust F _p becomes zero. Therefore, in the conventional film thickness control device 70 designed to reduce the gap g when the voltage is applied to extend the piezoelectric actuator 7, the thrust of the piezoelectric actuator 7, that is, the film thickness, is reduced when the gap g is decreased. The force pushing the control blade 2 is small.

Therefore, in the film thickness control device as described above, in order to reduce the gap g, it is necessary to apply a voltage to the piezoelectric actuator to extend it. However, the reaction force F increases as the gap g decreases, whereas the thrust F _{p of the} piezoelectric actuator decreases as the piezoelectric actuator expands. As a result, there is a drawback that the gap g cannot be made smaller than a certain value, and the film thickness control blade cannot be reliably held under the condition that the gap g is small, and the gap g becomes unstable.

Further, in a printing machine or the like, generally, the gap opening degree of the film thickness control blade (the value when the gap when it is expanded to the maximum is 100%) is 50% or less (especially, 20).
% To 30% (used frequently), narrow gap g
High utilization rate in. Therefore, in the conventional film thickness control device in which the piezoelectric actuator has to be expanded in order to reduce the gap g, the piezoelectric actuator has to be used in a region where the thrust is low. Moreover, there is a problem that the life of the piezoelectric actuator is shortened by applying a high voltage to the piezoelectric actuator for a long time.

The present invention has been made in view of the above-mentioned drawbacks of conventional examples, and an object of the present invention is to control the film thickness frequently used in a state where the gap between the rotary roller and the film thickness control blade is small. In the device, it is to drive the piezoelectric actuator in a region where the thrust is large and prevent the life of the piezoelectric actuator from being deteriorated.

[0011]

According to the film thickness control device of the present invention, a film thickness control blade is disposed on the outer peripheral surface of a rotary roller so as to face the outer peripheral surface of the rotary roller, and the gap amount between the outer peripheral surface of the rotary roller and the film thickness control blade is adjusted. In a film thickness control device for controlling the film thickness of a fluid supplied to the outer peripheral surface of a rotating roller by adjusting, the elastic member urges the film thickness controlling blade toward the rotating roller, and a piezoelectric actuator is activated. It is characterized in that the gap is expanded by extending the gap.

[0012]

In the present invention, the elastic member urges the film thickness control blade toward the rotary roller, and the piezoelectric actuator is extended to expand the gap between the rotary roller and the film thickness control blade. Therefore, the elastic member is configured to minimize the gap opening, and the gap is widened by driving the piezoelectric actuator. Therefore, when the gap is narrow, the amount of expansion of the piezoelectric element is small, the piezoelectric element is used in a region where the thrust is large, and small gap adjustment becomes easy.

For applications such as a printing machine where the gap opening is, for example, about 20% to 30% and the frequency of use is high when the reaction force to the film thickness control blade is large, the piezoelectric actuator is used in a large thrust region. Can be used in. Also, since the piezoelectric element is used in a state where the expansion amount is small,
When used in the same environment, the product of the applied voltage and time becomes small, and the life deterioration of the piezoelectric actuator is reduced.

Further, (pressurization by the elastic member)-(reaction force received by the film thickness control blade) is the thrust of the piezoelectric actuator. Therefore, the larger the reaction force, the smaller the thrust of the piezoelectric actuator and the larger the reaction force. The conditions are better.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic structure of a film thickness control device 40 according to an embodiment of the present invention. The film thickness control device 40 is provided with a film thickness control blade 2 facing the outer peripheral surface of the rotary roller 1, and a displacement generation device 50 on the opposite side of the rotary roller 1 with the film thickness control blade 2 interposed therebetween. The tip end of the output shaft 10 of the displacement generator 50 is brought into contact with the back surface near the tip of the film thickness control blade 2. The film thickness control blade 2 is made of an elastic plate such as a metal plate, and one end thereof is fixed to the support body 3.

In the displacement generator 50, a piezoelectric actuator (piezoelectric element) 7 for expanding the gap g is vertically provided on the inner wall 6a of the casing 6, and a movable block 8 is fixed to the tip of the piezoelectric actuator (piezoelectric element) 7. A compression spring 9 for urging the film thickness control blade 2 between the inner walls 6b of the casing 6 facing each other in the direction of the rotary roller 1 (X2 direction).
Is provided. The movable block 8 is provided with an output shaft 10 whose tip 11 is processed into a spherical or hemispherical shape in parallel with the piezoelectric actuator 7. The tip 11 of the output shaft 10 is processed into a spherical or hemispherical shape because the back surface of the film thickness control blade 2 and the tip 1 of the output shaft 10 as the gap g is opened and closed.
This is because of smooth sliding contact with 1.

When no voltage is applied to the piezoelectric actuator 7, the movable block 8 is pushed by the compression spring 9 in the X2 direction, and is pushed by the output shaft 10 fixed to the movable block 8. The film thickness control blade 2 is bent toward the rotary roller 1 side, and the gap g with the outer peripheral surface of the rotary roller 1 is 0 (this state is shown by an imaginary line in FIG. 1).

When a voltage is applied to the piezoelectric actuator 7 to expand it, the movable block 8 moves in the X1 direction against the compression spring 9, and at the same time, the output shaft 10 also retracts in the X1 direction and is pushed onto the output shaft 10. The film thickness control blade 2 that has been bent is elastically restored, and the gap g is widened (this state is shown by the solid line in FIG. 1). This gap g is adjusted by adjusting the voltage applied to the piezoelectric actuator 7.
It can be adjusted between 0% and 100% of the gap g (when the thrust is zero) when the maximum expansion is performed.

Accordingly, the film thickness control device 40 according to the present embodiment.
Therefore, in a general printing machine, under the condition that the gap opening, which is frequently used, is 20% to 30%, the piezoelectric actuator 7 can be used in a state in which the displacement amount is small and the thrust force F _p is large, and the film thickness control is performed. Even if the reaction force F to the blade 2 is large, the film thickness control blade 2 can be stably held. In addition, since the voltage applied to the piezoelectric actuator 7 at this time can be small, its life can be kept long.

FIG. 2 shows another displacement generator 60 used in the film thickness controller of the present invention. Box-shaped guide block 2
1, a piezoelectric actuator 22, a displacement enlargement / reduction mechanism 28 composed of three movable blocks 23a, 23b, 23c, and sliding plates 24a, 24b for reducing the friction coefficient of the movable blocks 23a, 23b, 23c, 24c,
24d, 24e and a compression spring 26 for urging the movable block 23c in the X3 direction are stored.

Generally speaking, the displacement enlarging / reducing mechanism 28 transmits displacements sequentially to a plurality of wedge-shaped movable blocks, and adjacent movable blocks are guided so as to be displaced in a direction substantially perpendicular to each other. Or the position is restricted. In addition, adjacent movable blocks are brought into contact with each other on each inclined surface directly or through friction reducing means,
The displacements are transmitted to each other through this inclined surface. Then, the ratio of the displacement amounts of the adjacent movable blocks is
Since the inclination angle is determined by the inclination angle of the inclined surface, by appropriately designing this inclination angle, the initial displacement can be enlarged or reduced to be output.

Referring to FIG. 2, the first movable block 23a is housed in the guide block 21 so as to be smoothly displaced in the X3-X4 direction in FIG. A sliding plate 24a is sandwiched between the inner surface of the guide block 21 and the inner surface. First
The piezoelectric actuator 22 is inserted between the end surface of the movable block 23a and the inner surface of the guide block 21, and the movable block 23a is configured to move in the X3-X4 direction as the piezoelectric actuator 22 expands and contracts.

The second movable block 23b is shown in FIG.
The movable block 2 is housed in the guide block 21 so that it can be smoothly displaced in the Y3-Y4 direction.
A sliding plate 24c is also sandwiched between the end surface of 3b and the inner surface of the guide block 21.

Further, the third movable block 23c is housed in the guide block 21 so as to be smoothly displaced in the X3-X4 direction in FIG. 2, so that the end surface of the movable block 23c and the inner surface of the guide block 21 are separated from each other. The sliding plate 24e is also sandwiched between them. A compression spring 26 is provided between the third movable block 23c and the inner surface of the guide block 21.
Is urged in the X3 direction by the repulsive force F _s of the compression spring 26.

Then, the two movable blocks 23a, 23
b are adjacent to each other so that the inclined surfaces 25a and 25b face each other, and the sliding plate 2 is provided between the inclined surfaces 25a and 25b.
4b is interposed. Similarly, the two movable blocks 23b and 23c are adjacent to each other with their inclined surfaces 25c and 25d facing each other, and a sliding plate 24d is interposed between the inclined surfaces 25c and 25d.

The sliding plates 24a, 24 shown
b, 24c, 24d, and 24e are, for example, sliding plates 24a shown in FIG. It was made to roll. Sliding plate 2
4a, 24b, 24c, 24d, and 24e may have other configurations, for example, polytetrafluoroethylene (PTFE) having high wear resistance and small friction coefficient.
Alternatively, a fluororesin-based sheet or the like may be used.

The displacement of the displacement generator 60 is fixed to the end surface of the third movable block 23c, and the output shaft 27 is projected from the opening 32 of the guide block 21 to the outside.
Output by. The tip of the output shaft 27 is shown in FIG.
Like the output shaft 10 of the displacement generator 50 of the film thickness control device 40, the film thickness control blade 2 is brought into contact with the back surface of the film thickness control blade 2.

Thus, for example, the piezoelectric actuator 22
When a voltage is applied to the piezoelectric actuator 22 and the piezoelectric actuator 22 is extended, the first movable block 23a moves to the piezoelectric actuator 2
The second movable block 2 is pushed by 2 and moves in the X3 direction.
3b is pushed by the inclined surface 25a of the first movable block 23a to move in the Y3 direction, and the third movable block 23c is pushed by the inclined surface 25c of the second movable block 23b and X4.
Move in the direction. Then, the output shaft 27 fixed to the third movable block 23c also moves in the X4 direction, the film thickness control blade 2 elastically returns, and the gap g is widened.

At this time, when the inclination angle of the inclined surfaces 25a and 25b is θ ₁ , the ratio of the displacement amount of the second movable block 23b to the displacement amount of the first movable block 23a is represented by cot θ ₁ . Similarly, when the inclination angle of the inclined surfaces 25c and 25d is θ ₂ , the ratio of the displacement amount of the third movable block 23c to the displacement amount of the second movable block 23b is represented by cot θ ₂ . Therefore, the ratio of the displacement amount of the third movable block 23c to the displacement amount of the first movable block 23a is
cot θ ₁ × cot θ ₂ . Therefore, the piezoelectric actuator 2
When the displacement amount of 2 is L and the minimum gap is g ₀ , the gap g between the rotating roller 1 and the film thickness control blade 2 is g
= KL + g ₀ . However, the proportional constant k = cot θ ₁
× cot θ ₂ .

Therefore, the thrust force F _p changes as shown in FIG. 4A in accordance with the change in the displacement amount L of the piezoelectric actuator 22, while the gap g changes as shown in FIG. 4B. That is, in a region where the gap g, which is frequently used in a general printing machine, is small, the displacement amount L of the piezoelectric actuator 22 is small and the thrust F _{p of the} piezoelectric actuator 22 is large.
Will grow. Therefore, the film thickness control blade 2 can be stably held.

[0031]

According to the present invention, since the gap opening is minimized by the elastic member and the gap is widened by the piezoelectric actuator,
When the gap is narrow, the amount of expansion of the piezoelectric element is small, the piezoelectric element is used in a region where the thrust is large, and it becomes easy to adjust the small gap.

Further, in applications such as a printing machine where the gap opening is, for example, about 20% to 30% and the frequency of use is high when the reaction force to the film thickness control blade is large, the piezoelectric actuator is used in a large thrust region. It can be used in and realizes a reasonable operating state. Further, since the piezoelectric element is used in a state in which the expansion amount is small, when used in the same environment, the product of the applied voltage and time becomes small, and the life deterioration of the piezoelectric actuator is reduced.

Since (pressurization-reaction force) is the thrust of the piezoelectric actuator, the larger the reaction force, the smaller the thrust of the piezoelectric actuator, and the larger the reaction force, the better the condition.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view of a film thickness control apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another displacement generation device used in the film thickness control device of the present invention.

FIG. 3 is a plan view showing a sliding plate of the same.

FIG. 4A is a diagram showing a relationship between a displacement amount of a piezoelectric actuator and a thrust force, and FIG. 4B is a diagram showing a relationship between a displacement amount of a piezoelectric actuator and a gap.

FIG. 5 is a cross-sectional view showing a conventional film thickness control device.

FIG. 6 is a diagram showing thrust force characteristics of a piezoelectric actuator (piezoelectric element).

[Explanation of symbols]

 1 rotating roller 2 film thickness control blade 7 piezoelectric actuator 9 compression spring

Claims (1)

[Claims] 1. A fluid supplied to the outer peripheral surface of a rotating roller by arranging a film thickness controlling blade on the outer peripheral surface of the rotating roller so as to face it and adjusting a gap between the outer peripheral surface of the rotating roller and the film thickness controlling blade. In the film thickness control device for controlling the film thickness, the elastic member urges the film thickness control blade in the direction of approaching the rotating roller, and the piezoelectric actuator is extended to expand the gap. A film thickness control device.