JPH0952426A - Rotary stencil printer - Google Patents

Abstract

(57) Abstract: In a rotary stencil printing machine, a minimum amount of printing ink required for stencil printing can always be supplied and maintained on the plate cylinder in a constant amount. SOLUTION: An ink-permeable cylindrical plate cylinder (2) having an outer peripheral surface mounted with a stencil sheet (3) and rotating around its own central axis, and a printing paper (P) are synchronized with the rotation of the plate cylinder. And a pressing mechanism (41) that presses the plate cylinder or the printing paper in close contact with each other in a moving state to transfer the printing ink supplied to the inner peripheral surface of the plate cylinder to the printing paper. In the rotary stencil printing machine (1), an ink reservoir (5) is slidably in contact with the inner peripheral surface of the plate cylinder (2) and between itself and the inner peripheral surface of the plate cylinder.
4) is formed and a doctor blade (5) for discharging printing ink from the plate cylinder to the plate cylinder is provided at a position different from the contact portion between the plate cylinder and the printing paper by the pressing mechanism, and the ink amount is stored in the ink reservoir. A detection means is provided.

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 an ink-permeable cylindrical plate cylinder which has a stencil sheet mounted on its outer peripheral surface and rotates around its own central axis. The present invention relates to a rotary stencil printer that can appropriately maintain the amount of ink supplied to the cylinder.

[0002]

2. Description of the Related Art A rotary stencil printing machine is provided with a cylindrical plate cylinder whose outer peripheral surface has a printing ink passage structure such as a porous structure, and the outer peripheral surface of the plate cylinder is used for locking a stencil sheet. Equipped with a clamper. At the time of printing, one end of the stencil sheet preliminarily perforated with the image and made into a plate is wound around the plate cylinder by locking it with a clamper, and the plate cylinder is rotated while printing ink is supplied to the inner peripheral surface of the plate cylinder. The stencil printing is performed by bringing the paper into close contact with the plate cylinder by a predetermined pressing mechanism in a state of translating the paper in synchronization with the rotation and transferring the printing ink impregnated in the plate cylinder to the printing paper.

When the plate cylinder is made of a material having a high rigidity, the pressing mechanism is often constituted by a press roller provided outside the plate cylinder so as to face the plate cylinder. The printing ink impregnated in the plate cylinder is transferred to the printing paper by the pressing force of the press roller that presses this. Further, a squeegee roller that rotates inscribed in the inner peripheral surface of the plate cylinder is provided facing the press roller, and the pressing force of the press roller is received by the squeegee roller to impregnate the plate cylinder with the printing ink. The pressing mechanism that transfers the to the printing paper is also often used.

In the latter pressing mechanism, a member called a doctor roller is arranged next to the squeegee roller with a slight distance from the squeegee roller, and the squeegee roller and the doctor roller are rotated by the rotation of the squeegee roller during printing. While the printing ink forms a vortex between them and is collected, the printing ink necessary for printing is transmitted as a film on the surface of the plate cylinder by the rotation of the squeegee roller from the slight gap between the squeegee roller and the doctor roller. A certain amount of printing ink is supplied.

In this case, the remaining amount of the printing ink on the plate cylinder can be judged by the size of the eddy of the printing ink formed between the squeegee roller and the doctor roller, and the printing ink is replenished between the squeegee roller and the doctor roller. By keeping the size of the vortex constant, the proper amount of ink on the plate cylinder can be maintained.

On the other hand, an example of using a plate-shaped squeegee blade that is in sliding contact with the inner peripheral surface of the plate cylinder instead of the squeegee roller is proposed in Japanese Patent Laid-Open No. 5-69649. In this case, an ink reservoir is formed between the squeegee blade and the inner peripheral surface of the plate cylinder, and the ink in the ink reservoir forms an ink vortex similar to the above when the plate cylinder rotates.

[0007]

In the rotary stencil printing machine using the above-mentioned squeegee roller, when printing is performed on an original having a small portion to be printed, the printing ink unnecessary for printing is an excess ink. Remains on the inner surface of the plate cylinder. A certain amount of it is transmitted to the surface of the squeegee roller and returns to the vortex of the printing ink, but there is a limit to the amount,
If the excess ink leaks out through the gap between the plate cylinder and the stencil sheet, it may stain the printing paper.

Further, in the rotary stencil machine using the squeegee blade, the shape of the squeegee blade and the plate cylinder in the vicinity of the squeegee blade change when pressed by the press roller, so that the squeegee blade and the inner peripheral surface of the plate cylinder are Since the space formed during the change causes the ink vortex to lack stability, the ink amount in the plate cylinder cannot be accurately measured by the ink vortex. As a result, when the excess ink is generated, it is accumulated below the plate cylinder and oozes from the plate cylinder to stain the printing paper.

The present invention relates to a rotary stencil printer,
It is an object of the present invention to always supply a fixed amount of the minimum amount of printing ink required for stencil printing to the plate cylinder, and to collect and retain excess ink unnecessary for printing.

[0010]

According to the present invention, the above object is to provide an ink-permeable cylindrical plate cylinder having an outer peripheral surface on which a stencil sheet is mounted and which rotates around its own central axis, and a printing sheet. At least one of the plate cylinder and the printing paper is pressed in close contact with each other while moving in synchronization with the rotation of the plate cylinder, and the printing ink supplied to the inner peripheral surface of the plate cylinder is printed. In a rotary stencil printing machine having a pressing mechanism for transferring the ink to the plate cylinder, an ink reservoir is formed between itself and the plate cylinder inner peripheral surface by making sliding contact with the plate cylinder inner peripheral surface, and from there the ink is transferred to the plate cylinder. A doctor blade for deriving is provided at a position different from the contact portion between the plate cylinder and the printing paper by the pressing mechanism,
Further, the invention is achieved by a rotary stencil printing machine characterized in that an ink amount detecting means is provided in the ink reservoir formed by the doctor blade.

That is, in the apparatus of the present invention, the doctor blade is provided so as to slide on the inner peripheral surface of the plate cylinder at a position separated from the position where the plate cylinder and the printing paper are in close contact with each other by the pressing mechanism. An ink reservoir is formed at a position separated from the contact position between the plate cylinder and the printing paper,
By making the ink vortex formed there stable and thus measuring the size of the ink vortex by arranging the ink amount detection means in this ink reservoir, the ink amount on the plate cylinder can be accurately observed. It has a feature in doing so.

The ink amount detecting means may be, for example, an ink reservoir due to a change in the capacitance between the detection electrode member and the ground electrode member that face each other with the ink reservoir portion in between as the ink amount changes. It is possible to use an ink amount detecting device such as that described in JP-A-58-62520, which detects the ink amount in each part. When the ink amount detecting means detects a shortage of the ink amount, if the printing ink is directly supplied from the predetermined ink supplying means to the ink reservoir portion in response to the ink detecting means, the ink amount of the plate cylinder is increased. Can always be kept constant. In addition, it is preferable to arrange an ink stirring pipe in the ink reservoir in parallel with the doctor blade in order to stabilize the ink vortex formed therein when the plate cylinder rotates.

The position at which this doctor blade is brought into sliding contact with the inner peripheral surface of the plate cylinder is the "downward side of rotation" of the plate cylinder, that is, the plate cylinder rotates clockwise when viewed in the central axis direction of the plate cylinder. In this case, the area is preferably in the right half of the plate cylinder, and preferably in the left half of the plate cylinder when the plate cylinder rotates counterclockwise as viewed in the central axis direction of the plate cylinder. In the present specification, the term "rotation rising side" of the plate cylinder means the remaining area on the "rotation falling side" of the plate cylinder. When the doctor blade is brought into sliding contact with the inner peripheral surface of the plate cylinder on the rising side of the plate cylinder, ink flows out from the ink reservoir to the plate cylinder bottom when the plate cylinder rotation is stopped. When the ink blade is brought into sliding contact with the inner peripheral surface of the plate cylinder on the descending side of the rotation, it is possible to prevent the ink from flowing downward from the ink reservoir when the plate cylinder stops rotating.

This doctor blade is brought into sliding contact with the inner peripheral surface of the plate cylinder to scrape off the excess printing ink of the plate cylinder during rotation of the plate cylinder, so that the doctor blade itself has a surface on the upstream side in the rotational direction of the plate cylinder and an inner peripheral surface of the plate cylinder. Any form may be used as long as an ink reservoir is formed between them and a predetermined amount of printing ink is pushed into the plate cylinder downstream therefrom in the rotational direction of the plate cylinder. It is preferably made of an elastic material such as rubber which extends parallel to the central axis and is in sliding contact with the inner peripheral surface of the plate cylinder.

The doctor blade can be formed integrally or integrally with the tip of a suitable supporting member, and the doctor blade that makes sliding contact on the lower side of the rotation of the plate cylinder is located below the sliding contact point between this and the plate cylinder. When provided by being supported by the tip of an arm member that is rotatable around a fulcrum arranged in a region near the rising side of the rotation of the plate cylinder, the weight of the arm member and the downward rotational movement of the plate cylinder cause It is preferable that the doctor blade operates so as to bite into the plate cylinder at the sliding contact points of both, and the ink reservoir is stably formed.

Further, it is preferable to provide dams at both ends in the longitudinal direction of the doctor blade, that is, both ends located in the central axis direction of the plate cylinder to prevent ink from leaking out from the ends.

According to the present invention, not only a rotary stencil printing machine using a press roller provided outside the plate cylinder as a pressing mechanism but also a squeegee roller or a squeegee blade is arranged inside the plate cylinder so as to face the press roller. In addition to the rotary stencil printing device described above, a roller is arranged inside the elastic plate cylinder, and a pressing mechanism for pressing the plate cylinder outward by the roller to bulge the plate cylinder into close contact with the printing paper is provided. It goes without saying that the invention can also be implemented in various rotary stencil printing apparatuses such as the rotary stencil printing apparatus provided.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A specific example of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to the specific example.

FIG. 1 schematically shows the whole stencil printing apparatus of the present invention, and numeral 1 shows the whole stencil printing apparatus. The stencil printing machine 1 includes a housing 10 in which an ink-permeable cylindrical plate cylinder 2 made of a material such as a highly rigid porous metal plate and a mesh structure is rotatably provided around its central axis. . On the outer periphery of the plate cylinder 2, the stencil sheet 3 is preliminarily image-punched by an image punching device (not shown).
The stencil sheet 3 can be mounted by winding the end of the stencil between the clamp 21 and the clamp base 22.

When performing printing, when a user of the apparatus turns on a printing start switch, a drive motor (not shown) rotates, and the plate cylinder 2 linked to the drive motor moves in the direction of arrow A. Start to rotate. Further, the drive motor is interlocked with a paper feed mechanism 61 for feeding the print sheet P from the guide plate 62 to the vicinity of the plate cylinder 2, and sequentially feeds the print sheet P to the vicinity of the plate cylinder 2 every rotation thereof. Then, when the printing paper P is sent to the vicinity of the plate cylinder 2, the sensor 63 recognizes the position of the printing paper P, and the press roller 41 is provided directly below the plate cylinder 2 so as to face the printing roller P and move up and down. Of the stencil sheet 3 on the outer peripheral surface of the plate cylinder 2 by pushing up in the direction of arrow D.
And press the arrow B in synchronization with the rotation of the plate cylinder 2.
Stencil printing is performed on the printing paper P by rotating in the direction of and feeding the paper. The stencil-printed printing paper P is separated from the plate cylinder 2 by the separating claw 65, passes through the guide plate 64, and is accommodated in the paper discharge tray 66.

In FIG. 1, a plate-shaped doctor blade 5 which is slidably contacted at a point C is provided on the inner peripheral surface of the plate cylinder 2,
As a result, since a groove 54 having a substantially V-shaped cross section is defined between the upper surface of the doctor blade 5 and the inner peripheral surface of the plate cylinder in the vicinity thereof, the groove 54 functions as an ink reservoir when the plate cylinder 2 rotates. , An ink vortex is formed there, and a certain amount of printing ink is discharged to the plate cylinder surface below the sliding contact C,
The plate cylinder 2 is kept in a state of containing a certain amount of printing ink.
In the present invention, the sliding contact C of the doctor blade 5 is
As long as the press roller 41 presses the printing paper P against the plate cylinder 2 at the time of printing, it may be anywhere on the inner peripheral surface of the plate cylinder 2, but as shown in FIG. It is convenient to set the lower side of the rotation of 2, that is, the left half region of the plate cylinder 2 in FIG. 1, because the printing ink is retained in the groove 54 even when the rotation of the plate cylinder 2 is stopped. ,in this case,
The plate-shaped doctor blade 5 is arranged so as to be tilted upward by an appropriate angle θ with respect to the horizontal line, and its upper surface extends from the sliding contact C while being tilted upward.

FIG. 2 is a schematic view showing the internal structure of another specific example of the plate cylinder 2 of FIG. 1, in which the plate cylinder 2 is on the descending side of its rotation.
That is, the doctor blade 5 which is in sliding contact with the inner peripheral surface of the plate cylinder 2 is provided in approximately the middle of the area on the side indicated by the symbol E. The doctor blade 5 is composed of a thick plate that extends in parallel to the central axis of the plate cylinder and is bent in an approximately L-shaped cross section, and rotates about an axis 51 that extends parallel to the central axis of the plate cylinder. The arm member 52 is movably attached to the plate cylinder 2, and the free end of the arm member 52 is in sliding contact with the inner peripheral surface of the plate cylinder 2 at a point C above the shaft 51. The free end is provided with a leading end surface 53 extending upward from the leading end portion slidingly contacting the printing drum 2 at the point C toward the inside of the printing drum, and the cross section is formed by the leading end surface 53 and the inner circumferential surface of the printing drum. Substantially V-shaped groove 5
Since the groove 4 is defined, the groove 54 functions as an ink reservoir. The printing ink is sent from the ink tank 71 to the distributor 73 arranged in the plate cylinder 2 by the ink pump 72, and is directly supplied to the groove 54 from there.

It is desirable that at least the tip of the doctor blade 5 that is in sliding contact with the plate cylinder is made of an elastic material such as rubber, but the entire body including the arm member 52 is integrally made of an elastic material such as rubber. It may be formed, or only the tip end portion may be formed of an elastic material such as rubber and attached to the arm member 52 made of another material such as metal. Thus, when the plate cylinder 2 rotates, the printing ink supplied to the groove 54 is pushed out to the plate cylinder 2 from the sliding contact C of the doctor blade 5 as the plate cylinder 2 rotates, and the excess ink that is not transferred to the printing paper is removed by the doctor. It is scraped off by the blade 5 and stored in the groove 54, so that the plate cylinder 2 is always kept impregnated with a fixed amount of printing ink. And the groove 54
The ink stored in the ink forms an ink vortex by the rotation of the plate cylinder. In addition, since the ink stirring pipe 55 is disposed in the groove 54 in parallel with the doctor blade 5, the printing ink is swirled around the ink stirring pipe 55 as the plate cylinder 2 rotates and forms a vortex. Stable formation of ink vortex.

Since this ink vortex is formed in the groove 54 provided at a position different from the position where the press roller 41 presses the stencil sheet P against the plate cylinder 2, it is not affected by the press roller 41. It is stably formed, and the size of this ink vortex accurately reflects the amount of ink in the plate cylinder. Therefore, by providing an ink amount detecting means (not shown) in the groove 54 and measuring the size of the ink vortex, the ink amount of the plate cylinder can be accurately measured. As the printing progresses, the size of the ink vortex becomes smaller. However, when the size of the ink vortex becomes smaller than a predetermined size, the ink amount detecting means reacts to operate the ink pump 72 and print from the distributor 73. Ink is supplied to the groove 54, and when the ink vortex becomes a predetermined size, the operation of the ink pump 72 is stopped to stop the ink supply, so that the ink amount on the plate cylinder is controlled to be constant. You can also

In the example of FIG. 2, the doctor blade 5 is shown in FIG.
It is convenient because the printing ink does not flow out from the groove 54 even when the rotation of the plate cylinder is stopped, because it is in sliding contact with the area on the lower side of the rotation of the plate cylinder indicated by the symbol E.
In the present invention, it does not prevent the doctor blade 5 from slidingly contacting the rising side of the rotation of the plate cylinder.

In the example of FIG. 2, the doctor blade 5
Is rotated about a shaft 51 provided below the sliding contact point C with the plate cylinder 2 and closer to the rising side of the rotation of the plate cylinder, that is, below the horizontal line H in FIG. 2 and on the right side of the vertical line V. Since the arm member 52 is mounted so as to be movable, the weight of the arm member 52 and the plate cylinder 2 are kept during rotation of the plate cylinder 2.
It is advantageous that the tip end portion of the doctor blade 5 is engaged with the inner peripheral surface of the plate cylinder by the downward rotation movement of the groove 54 and the groove 54 is stably formed.

FIG. 3 shows an example in which the present invention is applied to a rotary stencil printing machine in which the plate cylinder 2 is composed of a flexible screen having a fine porous structure in order to improve image quality. Since the plate cylinder 2 has a low rigidity, a squeegee roller 42 that faces the press roller 41 and is inscribed in the inner peripheral surface of the plate cylinder is rotatably arranged inside the plate cylinder. It differs from the example of FIG. 2 in that it is adapted to rotate in the direction of arrow F corresponding to the rotation of 2.

Also in the case of FIG. 3, since the sliding contact C of the doctor blade 5 is provided apart from the position where the press roller 41 presses the plate cylinder 2, the influence of the deformation of the plate cylinder 2 by the press roller 41 is affected. The groove 54 is stably defined without being received, and an ink vortex is stably formed in the groove 54 around the ink stirring pipe 55 when the plate cylinder 2 rotates.
As described above in connection with the above, it is possible to control the ink amount of the plate cylinder 2 to be constant, and the printing ink content of the plate cylinder 2 is always maintained at a constant amount, so that stable printing is performed. Note that, in FIG. 3, instead of the squeegee roller 42, a squeegee blade that does not include a rotating mechanism may be used.

Further, in FIG. 3, a weir plate 57 is provided at both longitudinal end portions of the doctor blade 5, that is, both end portions in the extending direction of the shaft 51, in order to prevent printing ink from leaking therefrom. This is different from the example of FIG. The weir 57 is rotatably attached to the shaft 51 in a relationship orthogonal to the shaft 51. As is clear from FIG. 4, the weir 57 is provided with a spring 58 arranged at the end of the shaft 51.
Is urged toward the end of the doctor blade 5 and abuts against the end of the doctor blade 5 so as to come into close contact therewith. Further, as is apparent from FIG. It is formed in an arc shape that is slidably contacted along the inner peripheral surface, thereby preventing the ink from leaking out from the end portion of the ink blade 5. It is also possible to provide a shaft different from the shaft 51 of the ink blade 5 and rotatably attach the dam 57 to the shaft 51. Below the sliding contact point C of the ink blade 5 with the plate cylinder 2 and on the rising side of the rotation of the plate cylinder, that is, FIG.
It is preferable to provide it in the region below the horizontal line H and to the right of the vertical line V because it is stable even during rotation of the plate cylinder.

[0030]

According to the present invention, in the rotary stencil printing machine, the doctor blade is slidably contacted with the inner peripheral surface of the plate cylinder at a position separated from the position where the plate cylinder and the printing paper are brought into close contact with each other by the pressing mechanism. Since it is provided in such a manner, the excess ink in the plate cylinder is scraped off by the doctor blade and held in the ink reservoir formed between the doctor blade and the plate cylinder, and is constantly kept constant from the ink reservoir. A quantity of ink is supplied to the plate cylinder. Furthermore, since the ink reservoir is formed at a position separated from the contact position between the plate cylinder and the printing paper, the ink vortex formed there during the rotation of the plate cylinder is stable, The size of the vortex accurately reflects the amount of ink in the plate cylinder, and by measuring this size,
The required amount of printing ink can be accurately supplied into the plate cylinder, the ink amount in the plate cylinder can be kept constant, and excess printing ink can be prevented from leaking from the plate cylinder.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an entire specific example of a rotary stencil printing apparatus of the present invention.

FIG. 2 is a side view showing an internal structure of a modified example of the plate cylinder of FIG.

FIG. 3 is a side view showing an internal structure of a modified example of the plate cylinder of FIG.

FIG. 4 is a plan view schematically showing the inside of FIG.

[Explanation of symbols]

 1 stencil printer 10 housing 2 plate cylinder 21 clamp 22 clamp base 3 stencil base paper 41 press roller 42 squeegee roller 5 doctor blade 51 shaft 52 arm member 53 surface 54 groove 55 ink stirring pipe 57 dam plate 58 spring 61 paper feed mechanism 62 guide Plate 63 Sensor 64 Guide plate 65 Separation claw 66 Paper ejection table 71 Ink tank 72 Ink pump 73 Distributor C Sliding contact point P Printing paper H Horizontal line V Vertical line

Claims (8)

[Claims] 1. An ink-permeable cylindrical plate cylinder having a stencil sheet mounted on its outer peripheral surface and rotating around its own central axis; and a printing paper sheet in a state of moving in synchronization with the rotation of the plate cylinder. In a rotary stencil printing machine having a press mechanism that presses at least one of the plate cylinder and the printing paper to bring them into close contact with each other, and transfer the printing ink supplied to the inner peripheral surface of the plate cylinder to the printing paper. A doctor blade that forms an ink reservoir between itself and the inner peripheral surface of the plate cylinder by sliding contact with the inner peripheral surface of the plate cylinder and draws printing ink from the ink reservoir to the plate cylinder by the pressing mechanism. A rotary stencil printing machine, characterized in that it is provided at a position different from the contact portion between the ink and the printing paper, and further, ink amount detecting means is provided at the ink reservoir formed by the doctor blade. 2. The rotary stencil printing machine according to claim 1, wherein the doctor blade is provided in sliding contact with the inner peripheral surface of the plate cylinder on the descending side of rotation of the plate cylinder. 3. A doctor blade extends parallel to the central axis of the plate cylinder and is in sliding contact with the inner peripheral surface of the plate cylinder, and extends upward from the sliding contact toward the inside of the plate cylinder. The rotary stencil printing apparatus according to claim 2, further comprising: 4. A doctor blade is provided at the tip of an arm member that is rotatable around a fulcrum located below the sliding contact with the plate cylinder and in the region near the rising side of the rotation of the plate cylinder. The rotary stencil printing machine according to claim 3, wherein 5. The printing ink is replenished directly to the ink reservoir from a predetermined ink supply means in response to the ink amount detection means when the ink amount detection means detects a shortage of the ink amount. The rotary stencil printing machine according to. 6. An ink agitation pipe, which stabilizes an ink vortex formed when the plate cylinder rotates, is arranged in the ink reservoir in parallel with the central axis of the plate cylinder.
The rotary stencil printing machine according to. 7. The rotary stencil printing machine according to claim 4, wherein both end portions in the longitudinal direction of the doctor blade are provided with weir plates for preventing ink from leaking from the end portions. 8. The rotary stencil printing machine according to claim 7, wherein the weir is rotatably supported by the fulcrum and is biased by a spring so as to abut against the longitudinal end of the doctor blade. .