JPH0348029B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inking device for use in offset or letterpress printing presses.

Conventionally, the inking device of a printing press uses a large number of rollers, about 10 to 20, to uniformly supply ink to the printing plate surface, but it is necessary for the inking roll to always provide a uniform ink supply to the printing plate surface. Despite this, the image caused a ghost phenomenon, which caused a decline in print quality.

In order to solve this problem, the Special Publication No. 53-27641
In the publication, ink 1 as shown in Figure 1 is applied to printing plate cylinder 2.
A large-diameter ink coating roll 3 attached to the ink coating roll 3 is mounted so that it is pressed in parallel with the ink coating roll 3 and rotates in the same direction as the ink coating roll, so that the contact portion rotates in the opposite direction to the ink coating roll. An inking device has been introduced which includes a small-diameter doctor roll 4 and a doctor member 5 for scraping off excess ink and appropriately controlling the ink film thickness.

In the apparatus shown in FIG.
The doctor member 5 contacts the doctor roll at two places and scrapes off the ink on the doctor roll.

Further, in the prior art as shown in FIG. 1, the doctor roll 4 is brought into pressure contact with flat surfaces 5a and 5b forming V-shaped grooves formed in the doctor member 5.

In addition, in the inking device as shown in FIG. 1, since the doctor roll 4 is a small diameter roll, the doctor member 4 is used to prevent the doctor roll from bending when it is brought into pressure contact with the inking roll.
This is prevented by That is, the doctor member 5
also serves as a backup member.

The advantage of this device is that before the ink on the inking roll comes into contact with the plate, the effects of the pattern on the plate are completely erased, that is, the ink film becomes an ink film with a uniform thickness, so no ghosting occurs.

Also, since the number of rollers, which is around 20 as in the conventional method, is not required, the printing machine is simplified.

Also, since there is only one roller, there is no need to worry about the ink drying on the roller, so there is the advantage that ink that dries quickly can be used.

Although such effects can be fully expected, one of the difficulties with this device is the doctor mechanism that scrapes off the ink from the doctor roll.

In other words, if the ink is not completely scraped off, the ink film on the inking roll will fluctuate. However, with the currently introduced mechanism shown in Figure 1, a sufficient scraping effect cannot be expected. That is, the doctor roll 4 and the doctor member 5
If the mechanical precision of the contact portion is not sufficient, it will be difficult to scrape uniformly, and it is not realistic to require such precision from the doctor member. Even if uniformity is achieved, if the doctor member does not completely scrape off the ink, it is difficult to achieve an appropriate ink film thickness (2μ to 10μ) for printing.
To explain this with reference to FIG. 2, the ink film thickness T determined by the pushing amount of the doctor roll 4 with respect to the ink application roll 3 and the speed ratio of the ink application roll 3 and the doctor roll 4 is Under the influence of the ink film thickness 4t adhering to the ink coating roll 4, the ink film thickness 3t formed on the inking roll 3 becomes thicker than T. In order to make the ink film thickness of 3t an appropriate ink film thickness, it is necessary to increase the pushing amount of the doctor roll 4 and increase the rotation of the doctor roll 4, which requires a large amount of energy. Further, the increased rotation of the doctor roll 4 increases the ink film thickness by 4t, making it difficult to control the film.

The present invention solves the above-mentioned drawbacks, and does not require excessive precision in the part where the doctor member contacts the doctor roll, and can completely squeegee ink using a doctor member processed within a practical range. The present invention provides a king device. In other words, the edge of the doctor member is used at the part where the doctor member contacts the doctor roll, and the doctor roll is made to deform to compensate for the machining error of the doctor member without applying excessive force.
It is designed to thoroughly scrape off ink.
Another advantage of the present invention is that ink pigment lumps and other dust cannot be avoided in the ink fountain, and the part where the doctor member contacts the doctor roll is soft, taking into account wear of the doctor roll. It is necessary to use a material (such as Teflon material), and it is easily scratched by dust. When the doctor member is scratched, the ink film becomes thicker due to the amount of ink coming out from the scratched area.
They appear as vertical lines on the printed surface. 1st
With a doctor member like the one shown in the figure, once a scratch occurs, it is difficult to repair and is not suitable for practical use. However, according to the device of the present invention, even if there is a scratch, by pushing the doctor member into the doctor roll, the contact portion of the doctor member is easily crushed to restore uniformity and eliminate the effects of the scratch.

On the other hand, when the doctor member shown in Fig. 1 is pushed in a little from a completely tangential state,
The surface in contact with the doctor roll is approximately twice as large as that of the present invention, and deformation does not easily occur unless an excessive force is applied.

Therefore, the present invention makes deformation easier by pressing the edge portion of the doctor member against the doctor roll while retaining the function of the doctor member as a backup member. , make the doctor's function stable,
A doctor function suitable for practical use can be provided.

The present invention will be described in more detail below with reference to the drawings.

FIG. 3 is an explanatory diagram of an embodiment of the inking device of the present invention, in which an inking roll 3 having a large diameter and a rubber-like elastic surface is in pressure contact with the inking roll 3 in parallel with the inking roll 3. Therefore, in the contact area with the ink forming roll, it is installed so as to rotate in the opposite direction to the inking roll, and scrapes off excess ink and appropriately controls the film thickness of the ink forming roll. A doctor roll 4 is provided, and the ink 1 is stored between the application roll 3 and the doctor roll 4. Further, the doctor roll 4 is provided with a doctor member 5 that contacts the doctor roll 4 at two places to scrape off ink on the doctor roll 4. The part where the doctor member 5 contacts the doctor roll 4 is a doctor blade 6 having a substantially U-shaped cross section and an opening size smaller than the diameter of the doctor roll 4. It is fixed to the holder 7, and the doctor roll 4 can be adjusted freely with the adjustment screw 8.
The contact pressure can be changed. Adjustment screw 8
is held by an adjustment screw holder 9. A perspective view of the doctor blade 6 is shown in FIG.

Ink 1 is stored between an ink application roll 3 and a doctor roll 4, and an ink plate 10 allows a large amount of ink to be stored. The ink plate 10 and the adjustment screw holder 9 are fixed to the ink side plate 11, and the doctor roll 4 is supported by a bearing metal provided on the ink side plate 11, and is driven by a drive mechanism such as a motor (not shown). driven.

The doctor roll 4 rotates in the direction of arrow 12 in the figure, and the doctor roll 4 comes out of the ink reservoir.
contacts the doctor member 5, and in this case, the portion where the doctor member 5 first contacts the doctor roll 4 is the end ridgeline portion 13 of the doctor member 5.

The doctor roll 4 is a small metal roll with a diameter of about 10 to 20 mm, and it easily bends due to contact pressure with the inking roll and rotation, so the doctor member 5 prevents this bending. The member 5 is in contact with the doctor roll 4 at two locations. In the case of FIG. 3, the doctor member 5 is in contact with the end ridgeline portion 13 and the other end ridgeline portion 14. In the case shown in FIG.

FIG. 5 is an explanatory view of another embodiment of the inking device of the present invention, in which the doctor roll 4 pressed against the inking roll 3 rotates in the same direction as in the case of FIG. Ink 1 is stored between the two rolls, and the doctor member 5 is in contact with the doctor roll 4 at three locations. The doctor roll 4 is rotating in the direction of arrow 12 in the figure, and the doctor roll 4 that comes out of the ink reservoir
The part that first comes into contact with the doctor member 5 is the doctor blade 6, which is an end ridgeline part of the doctor blade 6. The doctor blade 6 is attached to a doctor blade holder 7, and the doctor blade holder 7 has a substantially L-shaped cross section, as is clear from FIG.
The back-ups 17, 17 are in contact with the doctor roll 4 at the portions of the back-ups 17, 17 attached to the two flat surfaces 7a, 7b forming the letter shape. The ink plate 10 is attached to an ink plate holding member 16 that rotates around a doctor pressure adjustment shaft 15.
One end is in contact with the doctor blade 6.
The adjustment screw 8 is attached to an adjustment screw holder 9, and the adjustment screw 8 applies a rotational force to the ink plate 10, and this rotational force of the ink plate 10 is transmitted to the doctor blade 6 to change the doctor pressure. .

Adjustment screw holder 9, doctor pressure adjustment shaft 15,
The doctor holder 7 is fixed to the ink side plate 11. Doctor holder 7 is back up 1
The portions 7 and 17 are in pressure contact with the doctor roll 4 to prevent the small diameter doctor roll 4 from deflecting.

FIG. 6 is an explanatory view of another embodiment of the inking device of the present invention, in which the ink application roll 3 and the doctor roll 4 are rotated in different directions, are in contact with each other, or are the ink 1 stored between these two rolls. The conditions such as the presence of the above-mentioned components are the same as those of the other embodiments of the present invention described above. Doctor roll 4 coming out of the ink reservoir
The part that first comes into contact with the doctor member 5 is the end ridgeline part of the doctor blade 6, and the doctor blade 6 is attached to a doctor blade holder 7. The doctor blade holder 7 is moved by the adjustment screw 8 attached to the adjustment screw holder 9, and the contact pressure of the doctor blade 6 attached to the doctor blade holder against the doctor roll 4 can be changed. A back up holder 18 is attached closely to the doctor blade holder 7, and the back up 17 is attached to the back up holder 18 by means of a back up adjustment screw 19.
Mounted so that the pressure against it can be adjusted.
The back up 17 can prevent the small diameter doctor roll 4 from being bent. It is attached to the ink plate 10 in close contact with the doctor blade holder 7. The ink plate 10, the adjustment screw holder 9, and the backup holder 18 are fixed to the ink side plate 11.

FIG. 7 is an explanatory diagram of another embodiment of the inking device of the present invention, which has a similar structure to the device shown in FIG. 5, but the tip of the doctor blade 6 protrudes from the doctor blade holder. and
The difference is that the tip of the doctor blade is at an acute angle.

As described above in detail with reference to the drawings regarding the inking device of the present invention, in the present invention, the doctor member 5 is in contact with the doctor roll 4 at at least two places, and the doctor member 5 is in contact with the ink reservoir. The portion that first comes into contact with the doctor roll coming out of the doctor member 5 is the end ridgeline portion of the doctor member 5.

The material of the portion where the doctor member 5 contacts the doctor roll 4, that is, the doctor blade and back-up, is preferably a Teflon member or the like. Further, the ink-applying roll has a large diameter, and the diameter is generally about 10 cm to 20 cm.

According to the inking device of the present invention having the above-mentioned configuration, it is possible to prevent the small-diameter doctor roll from being bent, and also to compensate for machining errors in the doctor member, thereby making it possible to scrape off ink well. . Furthermore, even if the doctor blade is damaged by dust, if a soft material such as Teflon material is used as the doctor blade, the doctor pressure against the doctor roll can be temporarily strengthened.
The scratches can be easily eliminated, and by applying appropriate doctor pressure, the adverse effects of the scratches can be minimized.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a conventional inking device, Figure 2
The figure is a partially enlarged view of FIG. 1, FIG. 3 is an explanatory diagram of one embodiment of the inking device of the present invention, and FIG.
A perspective view of the doctor blade used in the figure,
5 to 7 show explanatory diagrams of other embodiments of the inking device of the present invention, respectively. 1... Ink, 2... Printing plate cylinder, 3... Ink deposit roll, 4... Doctor roll, 5... Doctor member, 6
…Doctor blade, 7…Doctor blade holder, 8…Adjustment screw, 9…Adjustment screw holder, 1
0... Ink plate, 11... Ink side plate, 12... Arrow,
13, 14... End ridgeline portion, 15... Doctor pressure adjustment shaft, 16... Ink plate holding member, 17... Backup, 18... Backup holder, 19... Backup adjustment screw.

Claims (1)

[Claims] 1. An ink application roll with a large diameter and a rubber-like elastic surface for applying ink to the printing plate cylinder of an offset or letterpress, and an ink application roll that is pressed parallel to the ink application roll and rotates in the same direction as the ink application roll. A doctor roll is attached to rotate in the opposite direction to the ink application roll and scrapes off excess ink to appropriately control the film thickness of the ink application roll, and the doctor roll is in contact with the doctor roll at at least two places. In the inking device, the inking device includes a doctor member that presses the doctor roll against the ink application roll, and ink is stored between the ink application roll, the doctor roll, and the doctor member, and the doctor member presses the doctor roll against the ink application roll. An inking device characterized in that the first portion that comes into contact with the doctor roll after touching is an end ridgeline portion of the doctor member.