JP2001232923A - Ink screening device for rotary stencil printing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an ink from leaking through the rear end side or side of a stencil base paper installed on a small-diameter plate cylinder. SOLUTION: The peripheral wall 2 of the plate cylinder 4 has an ink passing region and a non-passing region. An ink screening member 30 is arranged at the rear of a printing region with respect to the rotating direction R of the plate cylinder 4. The ink screening member 30 consists of a near saw-teeth-like basic material 31 and an elastic covering member 32 bonded with each other. Spaces 36 are formed between both the members. A portion covered by the ink screening member 30 has large- diameter openings 28 or a larger open area ratio, while a portion not covered has small-diameter openings 18 or a smaller open area ratio. At printing, an ink moves on the outer peripheral surface of the plate cylinder 4 towards the counter direction of the arrow R and enters the spaces 36. The covering member 32 deflects by being pressed with a press roller, resulting in returning the ink in the space 36 through the opening part 28 into the plate cylinder 4. As compared with the amount of the ink going out of the interior of the plate cylinder 4, the amount of the ink pushing back through the openings 28 covered by the ink screening member 30 is larger. Thus, no ink leaks to the outer peripheral surface side of the ink screening member 30. When the press roller separates from the covering member, the volume of the space 36 returns to its initial volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary stencil printing machine provided with a cylindrical plate cylinder on which a stencil sheet is mounted and rotated. The present invention relates to an ink shielding device for preventing ink leakage.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a schematic structure of a conventional general rotary stencil printing machine. The plate cylinder 4 of the rotary stencil printing machine has a cylindrical peripheral wall 2. The peripheral wall 2 has a printing area where a large number of openings 18 are formed and ink passes through, and a non-printing area where the openings 18 are not formed and ink does not pass. On the outer side of the peripheral wall 2, a mesh-shaped screen 6 that passes ink is wound. The perforated stencil sheet S is wound on the screen 6. A doctor roller 10 and a squeegee roller 12 are provided inside the plate cylinder 4.
The ink 14 staying in between is supplied to the inner surface of the peripheral wall 2 via the squeegee roller 12. A press roller 16 is provided outside the plate cylinder 4. The press roller 16 presses the printing paper P supplied between the printing drum 4 and the stencil sheet S wound around the printing drum 4 and transfers ink to the printing paper P to perform printing.

Generally, in such a rotary stencil printing machine, an ink shielding member 22 as shown in FIG. 4 is mounted at a position of a rear end portion of a plate cylinder 4 indicated by a symbol A in FIG. The ink shielding member 22 is a sheet material made of resin or the like. A half portion of the ink shielding member 22 is on the outer surface side of the printing region of the plate cylinder 4 and covers a portion behind the printing region with respect to the rotation direction of the plate cylinder 4. The other half of the ink shielding member 22 is fixed to the outer peripheral surface of the peripheral wall 2 via an adhesive layer 23. Although not shown, the length of the ink shielding member 22 in the plate cylinder axis direction is longer than the length of the portion where the plurality of openings 18 are formed in the printing area, and the opening 18 in the plate cylinder axis direction is formed. It covers the whole. In FIG. 4, a screen (not shown) is wound around the plate cylinder so as to cover the ink shielding member 22. The stencil sheet (not shown in FIG. 4, indicated by S in FIG. 3) attached to the outer peripheral side of the screen has a boundary between a plate making portion and a non-plate making portion when viewed from the axial direction of the plate cylinder. In the plate cylinder rotation direction, a little (for example, 1
(About 0 mm), and is mounted on the screen so as to come forward. The ink shielding member 22 has an opening 18 that is not involved in printing behind the printing area in the rotation direction of the plate cylinder 4.
And a member for blocking the supply of ink to the portion of the screen that is in contact with the non-stencil portion of the stencil sheet and the non-stencil portion of the stencil sheet.

[0004]

When printing is performed by the rotary stencil printing press, the press roller 16 presses the outer peripheral surface of the plate cylinder 4 via the printing paper as described above. The screen 6 wound around the outside of the plate cylinder 4 is filled with ink during printing. As shown in FIG. 4, when the press roller 16 rotates in the direction of arrow B while rotating with respect to the plate cylinder 4 (actually, the plate cylinder 4 rotates in the direction of arrow R with respect to the press roller 16; In order to pay attention to the behavior of the ink on the plate cylinder 4, it is assumed that the plate cylinder 4 is fixed.) Ink contained in the screen 6 (not shown) advances along the outer peripheral surface of the peripheral wall 2 in the direction of arrow C. When the ink reaches a predetermined amount, it passes over the ink shielding member 22 and advances on the outer peripheral surface in the direction of arrow D. Therefore, every time printing is performed, the amount of ink that gradually leaks to the outer peripheral surface side of the ink shielding member 22 increases, and this ink accumulates on the back side of the non-stencil part of the stencil sheet through the screen, and the rear end side of the stencil sheet Or it will seep from the side.

It is conceivable to reduce the amount of ink contained in the screen 6 to reduce the amount of ink seeping out from the rear end or side of the stencil sheet. However, this reduces the print density. Can not take such a method.

It is also conceivable to prevent the ink from passing over the ink shielding member by increasing the thickness of the ink shielding member. However, when the thickness is increased in this way, the front end of the ink shielding member blocks the ink. The applied ink easily flows in the axial direction of the plate cylinder, and the ink leaks from the side of the stencil sheet.

If the ink shielding member is not provided, the stencil sheet mounted on the outer peripheral side of the peripheral wall through the screen is a boundary line between the plate making portion and the non-plate making portion as viewed from the axial direction of the plate cylinder. Comes to the print area side by a predetermined length from the boundary line between the print area and the non-print area on the peripheral wall. In this case, compared with the case where the ink shielding member is provided, the outflow of ink in the plate cylinder radial direction from the rear side of the printing area is increased, and the ink is easily leaked from the rear end side of the stencil sheet. The length of the non-stencil portion of the stencil must be increased by the amount of the outflow.

During printing, the press roller 16 is used.
Is to press a stencil part of the stencil sheet mounted on the plate cylinder 4 and a slight margin before and after the stencil sheet through the printing paper.
It is driven in a direction approaching or separating from the plate cylinder 4. The press roller 16 is separated from the plate cylinder 4 when the stencil sheet clamp portion of the plate cylinder and the vicinity thereof pass.

In order to solve the problems described above, the present applicant has proposed an invention relating to an ink shielding member of a rotary stencil printing machine in Japanese Patent Application No. 6-293257. The present invention
It is disclosed in JP-A-8-150768.

The already proposed invention is applied to a plate cylinder of a rotary stencil printing machine as described above. As shown in FIG. 5, the peripheral wall 2 of the plate cylinder 4 has an ink passage area having holes 18 and an ink non-passage area having no holes. With respect to the rotation direction R of the plate cylinder 4, the ink shielding member 30 is located at a position behind the printing area.
There is. The ink shielding member 30 has a base member 31 and a cover member 32. The base member 31 has a plurality of substantially triangular pieces on the printing area.
Has 34. The cover member 32 has elasticity and is fixed to the upper surface of the base member 31. The covering member 32 and one adjacent portion of the base member 31
A space 36 is formed between the plate 34 and the outer surface of the printing area of the plate cylinder 4.

During printing, the ink moves on the outer peripheral surface of the plate cylinder 4 in the direction opposite to the arrow R, and flows into the space 36. The cover member 32 is elastically bent by being pressed by the press roller, and
The ink in 36 returns to the inside of the plate cylinder 4 from the opening 18 of the plate cylinder 4. The ink does not leak to the outer peripheral surface side of the ink shielding member 30. When the press roller separates, the volume of the space 36 returns to the original.

In recent years, stencil printing apparatuses in which the diameter of the plate cylinder is reduced have been developed for the purpose of reducing the size and weight. The small diameter of the plate cylinder means that the circumference of the plate cylinder is short. In such a stencil printing apparatus, when using the above-described ink shielding member to prevent ink leakage,
Since the circumferential length of the plate cylinder is short, the circumferential length of the ink shielding member is also short, and the function of preventing ink leakage and returning the ink into the plate cylinder cannot be sufficiently exhibited. That is, the function as the ink shielding member becomes insufficient.

Therefore, in a stencil printing apparatus in which the diameter of the plate cylinder is small and the degree of freedom in design is small, the ink shielding member proposed by the present applicant is improved so that ink leakage can be reliably prevented. Is required.

[0014]

According to a first aspect of the present invention, there is provided an ink shielding device for a rotary stencil printing press, wherein a peripheral wall having a printing area having a predetermined aperture ratio through which ink passes and a non-printing area through which ink does not pass. The present invention is applied to a plate cylinder of a rotary stencil printing machine provided with: The basic structure is provided on the outer surface side of the printing region of the plate cylinder and at a position behind the printing region with respect to the rotation direction of the plate cylinder. And a space communicating with the inside of the plate cylinder through the outer surface of a printing area of the plate cylinder, and having an ink shielding member having shape resilience for keeping the space at a predetermined volume. The feature is that the aperture ratio of a portion of the print area covered by the ink shielding member is larger than the aperture ratio of the other print areas.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The basic configuration of a rotary stencil printing machine to which the ink shielding device of this embodiment is applied is the same as that described in the section of the prior art. Regarding the configuration of the plate cylinder, reference numerals described in FIG. 3 are cited as necessary, and the description is omitted. 1 and 2, the screen is not shown.

An ink shielding member 30 is provided on the outer surface side of the printing region of the plate cylinder 4 and behind the printing region of the peripheral wall 2 with respect to the rotation direction (arrow R) of the plate cylinder 4. The ink shielding member 30 includes a base member 31 and a cover member 32.
Having.

The base member 31 is a substantially strip-shaped member made of a resin sheet having an appropriate thickness, and is attached to the outer surface of the peripheral wall 2 in parallel to the generatrix direction of the cylindrical plate cylinder 4.
The length of the base member 31 in the generatrix direction of the plate cylinder 4 is
Are formed in such a length as to cover the entirety of the openings formed in the plate cylinder 4 in the generatrix direction. The rear half of the base member 31 in the rotation direction R of the plate cylinder 4 is fixed to the outer peripheral surface of the non-printing area of the peripheral wall 2 via an adhesive layer 33. Plate cylinder 4
The front half of the base member 31 with respect to the rotation direction R of the plate cylinder 4 has a rotation direction R
Covers the rear part of the printing area. The front half of the base member 31 includes a plurality of substantially triangular pieces 34.
Are formed. These pieces 34 are arranged at a predetermined interval on the printing area of the plate cylinder 4.

The covering member 32 is a flaky member having elasticity or shape restoring property, and is made of resin or metal. The cover member 32 is fixed to the upper surface of the base member 31 via an adhesive layer 35.

A space 36 for accommodating ink is defined between the cover member 32, the adjacent pieces 34, 34 of the base member 31, and the outer surface of the printing area of the plate cylinder 4. . This space 36 is located on the outer surface side of the printing area of the plate cylinder 4 and at the rear of the printing area in the rotation direction R of the plate cylinder 4.

In the ink shielding device of this embodiment, the plate cylinder 4
Of the printing area (the ratio of the area where holes are formed on the peripheral surface of the plate cylinder) is not constant. 1 and 2
As shown in (2), the aperture ratio of the portion covered by the ink shielding member 30 in the print region is larger than the aperture ratio of the other print regions. Specifically, openings 18 are formed in a printing area in a portion not covered by the ink shielding member 30 with a size, an interval, and an arrangement such that an amount of ink suitable for stencil printing can be supplied. On the other hand, the ink shielding member 3
The printing area of the portion covered by 0 is a portion for returning the ink to the inside of the plate cylinder 4 without actually participating in printing, so that the opening 28 of this portion is larger than the opening 18. Is formed.

In this embodiment, the shapes of the openings 18 and 28 are circular, but this may be any shape. The arrangement is also arbitrary.

In this embodiment, at the time of printing, the ink that has exuded by the pressing of the press roller travels from the front to the rear in the plate cylinder rotating direction on the outer peripheral surface of the plate cylinder 4. That is, the ink moves on the outer peripheral surface of the plate cylinder 4 in the direction opposite to the arrow R.
This ink flows into the space 36 defined between the outer peripheral surface of the plate cylinder 4 and the ink shielding member 30, and does not leak to the outer peripheral surface side of the ink shielding member 30. When printing,
The covering member 32 of the ink shielding member 30 is
When pressed, the cover member 32 elastically flexes inward of the plate cylinder 4, and the volume of the space 36 decreases.
Therefore, the ink in the space 36 is filled with the opening 2 of the plate cylinder 4.
8, the ink in the space 36 does not leak to the outer peripheral surface side of the ink shielding member 30. Since the covering member 32 has elasticity or shape restoring property,
When the press roller 16 separates, the original shape is restored and the space 3
The volume of 6 is restored.

In a plate cylinder having a small diameter and a short circumference,
Since the circumferential length of the ink shielding member is also reduced, the volume of the space 36 for receiving the collected ink may not be sufficient. However, in this example, since the opening 28 that communicates with the space 36 and the inside of the plate cylinder 4 is formed with a larger aperture ratio than the opening 18 of a portion related to printing, the ink seeping out from the inside of the plate cylinder 4 is formed. Since the amount of ink pushed back from the opening 28 of the portion covered by the ink shielding member 30 is larger than the amount of the ink, the collected ink can be returned into the plate cylinder 4 without overflowing.

Therefore, in a stencil printing machine in which the diameter of the plate cylinder is small and the degree of freedom in design is small, it is possible to reliably prevent ink from leaking.

[0025]

According to the ink shielding device for a rotary stencil printing press according to the present invention, it is possible to prevent the ink from oozing out from the rear end or side of the stencil sheet mounted on a relatively small-diameter plate cylinder. Printing can be performed stably. Therefore, the degree of freedom in design is increased even for a plate cylinder having a relatively small diameter. Further, since the object can be achieved by means of changing the aperture ratio of the plate cylinder depending on the portion, there is no need to prepare new parts separately for that purpose, and there is an effect that the required cost can be minimized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an ink shielding device according to an example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line EE in FIG. 1;

FIG. 3 is a diagram showing a schematic configuration of a general rotary stencil printing machine.

FIG. 4 is a cross-sectional view showing a conventional ink shielding member.

FIG. 5 is a perspective view showing an ink shielding device proposed by the present applicant.

[Explanation of symbols]

 2 peripheral wall 4 plate cylinder 18 opening not covered with ink shielding member 28 opening covered with ink shielding member 30 ink shielding member 31 base member 34 piece 32 covering member

Claims (1)

[Claims] The present invention is applied to a plate cylinder of a rotary stencil printing press having a peripheral wall having a printing area with a predetermined aperture ratio through which ink passes and a non-printing area through which ink does not pass. The outer surface side is provided at a position behind the printing area with respect to the rotation direction of the plate cylinder, and opens toward the front in the rotation direction of the plate cylinder and communicates with the inside of the plate cylinder through the printing area. An ink shielding device for a rotary stencil printing machine having an ink shielding member configured between the outer surface of a printing area of the plate cylinder and a shape restoring property for maintaining the space in a predetermined volume, wherein the printing area includes An ink shielding device for a rotary stencil printing machine, wherein an aperture ratio of a portion covered by an ink shielding member is larger than an aperture ratio of other printing areas.