JP3188533B2 - Printing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus and, more particularly, to an ink supply mechanism provided inside a plate cylinder.

[0002]

2. Description of the Related Art Conventionally, a stencil printing apparatus is known as one of printing apparatuses. This printing apparatus is a plate cylinder provided with an ink passage structure for printing a printing base paper having a hole corresponding to an image formed by plate making. And a structure in which the ink is exuded from the inside of the plate cylinder to transfer the ink to the paper in close contact with the base paper. Then, among the structures used for this printing, a structure for supplying ink includes a structure shown in FIG. That is, the ink supply structure includes an ink supply roller B positioned inside the plate cylinder A and arranged with a slight gap between the ink supply roller B and the inner surface of the plate cylinder peripheral wall. And a doctor roller C disposed with a small gap for carrying ink between the ink supply pipe and an ink supply pipe for discharging ink toward an ink reservoir formed by the ink supply roller B and the doctor roller C D.

[0003] The ink supply roller B and the doctor roller C are both rotatably supported by an ink roller side plate E fixed to an ink supply pipe D. Is applied on the ink supply roller B with a constant thickness through a gap between the rollers. Then, the ink carried on the ink supply roller B exudes from the perforated portion of the printing base paper F via the porous metal base and the screen layer of the plate cylinder, and is transferred to the printing paper.

[0004]

Incidentally, the hardness of the ink applied to the peripheral surface of the ink supply roller B by the doctor roller C changes according to the environmental temperature in which the ink is used. The change may change the print density on the printing paper. That is,
Generally, printing inks have higher hardness at lower temperatures, and tend to be softer at higher temperatures. Therefore,
Even in the case where a constant amount of ink is to be supplied while maintaining a constant gap between the ink supply roller B and the doctor roller C, the amount of ink bleeding decreases because the temperature becomes low and the ink is easily cured. In addition, when the temperature rises, the ink tends to soften, so that the amount of oozing of the ink increases. Therefore, when the temperature is low, the image density on the printing paper decreases due to the decrease in the amount of ink bleeding, and when the temperature is high, the image bleeding amount increases due to the increase in the amount of ink bleeding. May be too high. As described above, even when the supply state of a certain amount of ink is set by the gap setting between the rollers described above,
The image density changes according to the change of the use environment, and there is a possibility that a stable image density cannot be obtained.

Therefore, conventionally, the doctor roller C is urged by a resilient member such as a spring so as to approach the peripheral surface of the ink supply roller, and the pressure of ink penetration between the doctor roller and the doctor roller changes depending on the hardness of the ink. A structure has been proposed in which a doctor roller is displaced to change a gap between the doctor roller and an ink supply roller.
-198557). According to this structure, when the hardness is high, the pressure of the ink when penetrating between the doctor roller and the ink supply roller increases, so that the doctor roller is extended in a direction in which the gap between the ink supply roller and the ink roller is pushed. Can be displaced, thereby increasing the ink supply. Also, when the hardness is low and softened, the urging force of the elastic member against the doctor roller is superior, so that the doctor roller can be displaced in a direction to narrow the gap between the ink supply roller and the doctor roller. This reduces the supply of ink.

However, in such a structure for stabilizing the ink supply amount, the pressure on the ink supply roller must be equalized in the axial direction of the doctor roller. It was troublesome. Moreover, in the axial direction of this doctor roller,
If the consumption of ink used for printing is the same, a constant amount of ink can always be supplied in accordance with temperature changes in the axial direction, but if the amount consumed in the axial direction differs, it will be stable in the axial direction. Supply could not be performed. In other words, when the solid image is deviated to one side in the axial direction of the doctor roller, a large amount of ink is consumed in that part, and the ink in the ink pool necessary to displace the doctor roller is displaced. Is insufficient, and the amount of ink supply is reduced due to the reduced amount of displacement of the doctor roller. Therefore, despite the necessity of consuming a large amount of ink, if the supply amount of ink is insufficient, the density of a printed image will not be a predetermined one, and density unevenness will occur.

Therefore, an object of the present invention is to solve the problem in the conventional printing apparatus described above and to solve the shortage of ink supply caused by a change in the hardness of ink due to a difference in use environment with a simple configuration. An object of the present invention is to provide a printing apparatus capable of stabilizing an image density by performing stable ink supply.

[0008]

In order to achieve the above object, the present invention provides a printing apparatus having an ink supply mechanism inside a rotatable cylindrical porous plate cylinder.
The ink supply mechanism is provided so as to be in contact with the inner peripheral surface of the plate cylinder, and is a rotatable ink supply roller that is interlocked with the plate cylinder; and a doctor that is disposed in parallel with an axial direction of the ink supply roller. And a roller, wherein the doctor roller is
One end in the extension direction is a base end supported by the immovable part,
The other end in the extension direction is rotatably supported by a doctor roller holding member having a free end, and the doctor roller holding member expands and contracts in the extension direction due to temperature, so that the supporting doctor roller and ink supply are provided. It is characterized in that the gap between the rollers is changed.

According to a second aspect of the present invention, the doctor roller holding member is characterized in that its extending direction is set to a direction coinciding with the normal line of the ink supply roller.

[0010] The invention according to claim 3 is characterized in that the doctor roller holding member is provided with amplifying means for increasing the amount of expansion and contraction along the extension direction due to temperature.

[0011]

According to the present invention, the doctor roller facing the ink supply roller is provided with a gap between the doctor roller and the ink supply roller due to expansion and contraction of the doctor roller holding member supporting the ink roller due to a change in environmental temperature. The size can be changed. Therefore, a state in which the supply amount of the ink is substantially constant according to the environmental temperature can be obtained by changing the gap.

Further, according to the present invention, the amount of the doctor roller holding member when it expands and contracts due to the environmental temperature is amplified, so that even if the amount of expansion and contraction is small, the doctor necessary to stabilize the supply amount of the ink. The amount of displacement of the roller can be set.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a schematic view showing the structure of a main part of the present invention. In FIG. 1, although the details of the plate cylinder 1 are not shown, the plate cylinder 1 is located in a range corresponding to a printing base paper winding section in the circumferential direction. A metal plate that has a large number of holes and is used as an ink passage section, and is a cylindrical member that can rotate normally and reversely and has an ink passage structure in which a screen layer using, for example, polyester fiber is arranged on the outer surface thereof. It is configured.

On the other hand, an ink supply unit 2 is arranged inside the plate cylinder 1, and the ink supply unit 2 approaches or comes into contact with the inner peripheral surface of the plate cylinder 1 and is capable of interlocking with the plate cylinder 1. A supply roller 2A and a doctor roller 2B disposed close to the ink supply roller 2A with a predetermined gap.
And In the ink supply unit 2, for example, ink discharged from an ink supply pipe 2C provided on a spindle of the plate cylinder 1 is accumulated in an ink reservoir formed at a position facing the ink supply roller 2A and the doctor roller 2B. After being kneaded by these two rollers, the ink supply roller 2A conveys the kneaded ink to a position where the plate cylinder 1 and the plate cylinder 1 face each other.

The above-mentioned doctor roller 2B is rotatably supported by a doctor roller holding member 3 described later. That is, the doctor roller holding member 3 has a base end supported by the side plate 4 supporting the ink supply roller 2A, and is constituted by a lever extended in a direction coinciding with a normal line of the ink supply roller 2A. A long hole 3A is formed in the free end of the doctor roller holding member 3 along the extending direction, and a pin 5 fixed to the side plate 4 is inserted into the long hole 3A. As shown in FIG. 2, both ends in the axial direction of the doctor roller 2B are supported at positions on the free end side of the doctor roller holding member 3 facing the ink supply roller 2A. This doctor roller holding member 3
As shown in FIG. 2, the fulcrum pin 6 used to support the base end portion and the head formed on the above-mentioned pin 5 are prevented from coming off, and are held in a state where they do not swing. ing.

The doctor roller holding member 3 is made of a material such as a polyacetal resin called Delrin, which has a relatively large coefficient of linear expansion and a remarkable expansion and contraction due to a temperature change. It can be expanded and contracted in the extension direction according to the change.

Next, the operation will be described.

Since the base end of the doctor roller holding member 3 located at one end in the extension direction is fixed by the fulcrum pin 6, when the temperature rises, the free end located at the other end in the extension direction holds the pin 5 in place. It will extend as a guide member.
Therefore, when the ink is easily softened at a high temperature, the doctor roller holding member 3 is extended, and the doctor roller 2B supported by the member moves to the ink supply roller 2A side, and the gap between the two rollers is reduced. Be narrowed.

When the temperature is low and the ink is easily cured, the doctor roller holding member 3 contracts, contrary to the case described above, so that the doctor roller 2B supported by the doctor roller 2B is moved from the ink supply roller 2A. It moves in the separating direction, and the gap between both rollers is widened.

In this embodiment, when a polyacetal resin is used as the material of the doctor roller holding member 3, the linear expansion coefficient is 81 × 10 ⁶ / ° C.
In the case where the dimension indicated by the symbol L is set to 30 mm,
The amount of change in the clearance between both rollers according to a temperature change of 10 ° C. is about 0.024 mm.

Therefore, when the ambient temperature is low and the hardness of the ink is high, the position of the doctor roller 2B with respect to the ink supply roller 2A is increased to widen the gap between the rollers, thereby increasing the ink supply amount. When the ink is easily softened due to a high environmental temperature, the position of the doctor roller 2B with respect to the ink supply roller 2A is reduced to narrow the gap between the rollers, thereby reducing the amount of ink supply. Will be.

According to this embodiment, the ink can be always supplied in a stable amount even when the environmental temperature changes. That is, since the doctor roller holding member 3 expands and contracts in response to a change in temperature, the doctor roller 2B supported by the doctor roller changes its position with respect to the ink supply roller 2A to automatically change the gap between the two rollers. Can be.

In contrast to the structure described in the above-mentioned publication, in this embodiment, the doctor roller holding member 3 does not change the position of the doctor roller 2B due to the hardness of the ink but changes its own expansion and contraction. Since the position of the doctor roller 2B is changed, it is possible to cause the same amount of position change over the entire area of the doctor roller in the axial direction. Therefore, even if a large amount of ink is consumed for printing a solid image in the axial direction, the doctor roller 2B is not displaced by using the pressure from the ink, so that the ink supply roller 2A is Can be properly secured.

On the other hand, the above-mentioned doctor roller holding member 3
For example, if the amount of expansion and contraction due to temperature change is small, it may not be possible to obtain the amount of displacement of the doctor roller sufficient to change the amount of ink supply.

Therefore, in the present embodiment, a configuration for coping with such a case is adopted. FIG. 3 shows a structure for increasing the amount of expansion and contraction of the doctor roller holding member. In this structure, the doctor roller holding member 30 is provided rotatably around the fulcrum pin 6,
A doctor roller 2B is rotatably supported at one end across the rotation center. The fulcrum pin 6 located at the center of rotation of the doctor roller holding member 30 is arranged at a position where the doctor roller 2B can set a rotation locus along the normal line of the ink supply roller 2A. Further, the distance to the spindle of the doctor roller 2B located at one end of the doctor roller holding member 30 across the rotation center,
In other words, the distance L1 corresponding to the displacement output side and the distance to the other end across the rotation center, in other words, the distance L2 corresponding to the displacement input side, are the distance (L2) on the displacement output side.
Is set to be larger than the distance (L1) on the displacement input side (L1 <L2).

An adjustment lever 7 is provided at the other end of the rotation center with respect to the center of rotation, which can be expanded and contracted by a change in temperature. The adjustment lever 7 is provided for the ink supply roller 2A.
The extension direction parallel to the normal direction is set, one end in the extension direction is fixed by a fixing pin 8 attached to the side plate 4, and the other end in the extension direction is the other end across the rotation center of the doctor roller holding member 30. Part.

Therefore, when the environmental temperature rises, the adjusting lever 7 extends, and the amount of extension is transmitted to the other end of the doctor roller holding member 30 across the rotation center. The doctor roller holding member 30 is rotated clockwise in FIG. 3 by the other end being pushed and moves the doctor roller 2B provided at one end across the rotation center to the ink supply roller. Move toward 2A. When the temperature becomes low, the adjustment lever 7 contracts, and the doctor roller holding member 3
0 rotates counterclockwise in FIG. 3 to move the doctor roller 2B located at one end across the center of rotation away from the ink supply roller 2A.

Accordingly, the amount of extension displacement of the adjusting lever 7 which occurs when the temperature becomes high and the ink is likely to be softened is converted into the amount of displacement on the displacement output side while being increased by the lever ratio of the doctor roller holding member 30. Therefore, even if the extension amount of the adjustment lever 7 is small, the gap between the two rollers is narrowed, and the supply amount of ink is reduced. Also,
Conversely, when the ink temperature is lowered and the ink is hardened easily, the displacement amount when the adjusting lever 7 contracts is increased by the lever ratio of the doctor roller holding member 30 in the same manner as described above. Thus, even if the amount of displacement of the adjustment lever 7 is small, the clearance between the two rollers is increased, and the amount of ink supply is increased.

To explain this point, for example, a material having a linear expansion coefficient smaller than that of the polyacetal resin which is the material of the doctor blade holding member used in the above embodiment, for example, having a linear expansion coefficient of about 23 × 10 to ⁶ ° C. When aluminum is used as the material of the adjusting lever 7, the distance between the fixing pin 8 and the center position in the width direction of the doctor roller holding member 30 in the extending direction is L = 30 mm in the same manner as in the above-described embodiment. Is 0.00 with a temperature change of 10 ° C.
A displacement amount of only about 7 mm can be obtained, and in order to achieve a displacement amount similar to that of the above-described embodiment, it is necessary to secure a displacement amount of about 3.5 times. However, in this embodiment, the lever ratio of the doctor roller holding member 30, that is, the distance between the displacement input side and the output side of the doctor roller holding member 30 with respect to the slight displacement amount of the adjustment lever 7. By increasing the ratio, the displacement amount on the output side can be amplified.

[0031]

As described above, according to the present invention, the doctor roller is rotatably supported by the doctor roller holding member which can expand and contract in response to a change in temperature. Irrespective of the changing ink hardness, the gap between the ink supply roller and the doctor roller is automatically adjusted, so that a constant amount of ink can always be supplied. Moreover, since the change in the ink hardness due to the temperature change is not used for the displacement of the doctor roller, even if a large amount of ink is partially consumed in the axial direction of the doctor roller, the pressure from the ink is reduced. The gap between the doctor roller and the ink supply roller can be appropriately secured even in a position where the ink tends to be insufficient, without displacing the doctor roller due to the change.

Further, according to the present invention, even if the amount of expansion and contraction according to the temperature change is very small, the amount of displacement can be amplified, so that the gap between the doctor roller and the ink supply roller can be increased. It becomes possible to secure a displacement amount of the doctor roller sufficient to correct the ink supply amount by forming.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a main configuration of a printing apparatus according to the present invention.

FIG. 2 is a sectional view taken in the direction indicated by reference numerals in FIG.

FIG. 3 is a schematic diagram showing a modification of the main part configuration shown in FIG. 1;

FIG. 4 is a schematic view showing a conventional example regarding the structure of an ink supply mechanism in a printing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plate cylinder 2 Ink supply mechanism 2A Ink supply roller 2B Doctor roller 3 Doctor roller holding member 4 Side plate which is an immovable part 5 Pin 6 Support pin 7 Adjusting lever 30 Doctor roller holding member

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41L 13/18 B41F 31/02

Claims (3)

(57) [Claims] 1. A printing apparatus provided with an ink supply mechanism inside a rotatable cylindrical porous plate cylinder, wherein said ink supply mechanism is disposed so as to be able to contact an inner peripheral surface of said plate cylinder. And a doctor roller disposed in parallel with the axial direction of the ink supply roller, wherein the doctor roller has one end in an extension direction supported by an immovable portion. The doctor roller holding member is rotatably supported by a doctor roller holding member whose other end in the extending direction is a free end, and the doctor roller holding member expands and contracts in the extending direction by temperature, thereby supporting the doctor roller. A gap between the ink supply roller and the ink supply roller. 2. A printing apparatus according to claim 1, wherein said doctor roller holding member has an extending direction corresponding to a normal line of an ink supply roller. 3. The printing apparatus according to claim 1, wherein the doctor roller holding member includes an amplifying means for increasing an amount of expansion and contraction along the extension direction due to temperature.