JPH06127107A - Printing machine - Google Patents

Abstract

PURPOSE:To provide a printing machine having a simple structure which prevents the generation of the impact noise and bound phenomenon of a press roller and also the density dispersion in an image in advance. CONSTITUTION:A part of the outside wall of a plate drum 1 is divided to form an overlapping part 2A. One side of the overlapping part 1A is a fixed part 1A1, while the other side is a movable part 1A2. The movable part 1A2 is separated from the fixed part 1A1 to form a space for inserting the end of a printing sheet. When the end of the printing sheet is put out, the movable part 1A2 is brought into contact with the fixed part 1A1 to hold the end of the printing sheet. Accordingly, by using a part of the outside wall of the plate drum 1 for a clamping mechanism which has been installed so far, a member projecting from the outside wall of the plate drum 1 can be eliminated, so that the spaces between the plate drum surface and a press roller 3 and between the surface and a peeling nail 4 can be made smaller.

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 a structure for sandwiching a printing base paper corresponding to a plate in a plate cylinder used in a stencil printing apparatus.

[0002]

2. Description of the Related Art Conventionally, a stencil printing device has been known as one of printing devices. This printing device is a plate cylinder provided with an ink passage structure for a printing base paper in which holes corresponding to an image are formed by plate making. It has a structure in which the ink is exuded from the inside of the plate cylinder to transfer the ink to the paper that is in close contact with the base paper. Then, among the structures used for this printing, the structure of the main part has a structure shown in FIG. That is, the printing apparatus includes a rotatable cylindrical plate cylinder B on which a printing base paper A corresponding to a perforated plate is wound, and a plate cylinder B.
A press roller C that can be brought into and out of contact with a printing base paper that is wound around an ink supply roller D that is located inside the plate cylinder B.
And an ink supply mechanism D for bringing 1 into contact with or in contact with the inner peripheral surface of the plate cylinder.

In such a printing apparatus, one end in the longitudinal direction of the printing base paper A is clamped by a clamp mechanism E provided on the plate cylinder B, and the printing base paper A is adhered by ink oozing out from the plate cylinder B. Then, the printing base paper A is held on the surface of the plate cylinder B. Then, when a sheet is fed out from a sheet feeding mechanism (not shown) and the sheet faces the press roller C, the press roller C comes into contact with the printing base paper A, so-called the printing base paper A and the paper are brought into close contact with each other, and the printing base paper is The ink that oozes out of the paper is transferred onto the paper. In FIG. 5, reference numeral F indicates a peeling claw for peeling the printing base paper A attached to the surface of the plate cylinder B.

[0004]

By the way, the press roller C moves the printing base paper A onto the surface of the plate cylinder B by a cam or solenoid (not shown) which rotates in synchronization with the rotation of the plate cylinder B during printing. The contact time is the time when the clamp mechanism E on the plate cylinder B side passes a position facing the press roller C. At this time, the press roller C is displaced at high speed. And hits the surface of the plate cylinder B. Such high-speed displacement is performed in order to minimize loss of the print image on the paper behind the clamp position of the printing base paper A.

Therefore, such a high-speed displacement of the press roller C causes a so-called collision state when it comes into contact with the surface of the plate cylinder B, and a large impact sound is generated or it bounces and vibrates on the surface of the plate cylinder. There is a possibility that such a phenomenon may be induced, resulting in uneven density at the image leading edge position on the paper.

Therefore, conventionally, there has been proposed a structure for avoiding the above-mentioned problem by providing an impact absorbing member at an initial pressure position on the plate cylinder side where the press roller abuts at the start of printing.
(For example, JP-A-3-136890).

However, even when such a shock absorbing member is provided, it is not possible to sufficiently prevent the impact noise and suppress the vibration of the press roller.

That is, in FIG. 5, the peeling claw F is provided between the surface of the plate cylinder B as much as possible in order to prevent the printed sheet from sticking to the plate cylinder B and rolling up as the plate cylinder rotates. It is desirable to reduce the gap (distance indicated by reference numeral S1 in FIG. 5) so as to approach the vicinity of the peripheral surface. However, when the shock absorbing member is arranged on a part of the peripheral surface of the plate cylinder, the shock absorbing member projects from the surface of the plate cylinder. Therefore, avoid the interference of the tip of the peeling claw F with this member. You have to move away in meaning. Therefore, in order to bring the tip of the peeling claw F closer to the peripheral surface of the plate cylinder as much as possible, the thickness of the shock absorbing member in the radial direction of the plate cylinder must be made as thin as possible. As described above, when the thickness of the shock absorbing member is reduced, the cushioning function is naturally reduced, and it becomes impossible to sufficiently absorb the shock.

Further, due to the thickness of the shock absorbing member located on the peripheral surface of the plate cylinder, a step is generated in the peripheral direction of the surface of the plate cylinder,
The pressing force when the press roller C passes through the step changes. When such a change in the applied pressure occurs, the pressing force applied by the press roller may be uneven, and for example, the image density may not be in a predetermined state and may be non-uniform.

Further, in order to prevent the generation of such impact noise, it is conceivable to displace the press roller relatively gently. In this case, however, until the press roller contacts the plate cylinder surface. During that time, no transfer of ink from the printing base paper to the paper should take place. Therefore, the circumference of the plate cylinder that moves until the press roller contacts the surface of the plate cylinder becomes longer as the displacement of the press roller becomes gentler, and the outer diameter dimension of the plate cylinder itself becomes large accordingly. However, it cannot be denied that the printing apparatus becomes large.

In view of the above-mentioned problems in the conventional printing apparatus, the object of the present invention is to prevent the impulsive sound and the bounce phenomenon of the press roller from occurring with a simple structure and to prevent the uneven density of the image. It is an object of the present invention to provide a printing apparatus having a structure that can be prevented.

[0012]

In order to achieve this object, the invention according to claim 1 is provided with a rotatable cylindrical porous plate cylinder, and a perforated printing base paper is wound around the cylindrical plate cylinder. ,
In a printing device that performs printing by pressing a sheet against the cylindrical plate cylinder by a pressing member composed of a press roller, a polymerized portion is provided in the circumferential direction of the cylindrical plate cylinder, and one of the polymerized portions serves as a fixed portion, Then, the other is a movable part that can be brought into contact with and separated from the fixed part, and the printing base paper is sandwiched between the overlapping parts by a bending force generated when the movable part is moved in a direction away from the fixed part. It has a feature.

According to a second aspect of the present invention, in the printing apparatus according to the first aspect, friction increasing means is provided at a position facing the printing base paper sandwiched by the overlapping portion of the cylindrical plate cylinder. I am trying.

According to a third aspect of the present invention, in the printing apparatus according to the first aspect, the printing base paper is sandwiched in a state where the leading end of the printing base paper is folded back to one of the overlapping portions and then wound around the cylindrical plate cylinder. The feature is that it has become.

According to a fourth aspect of the invention, in the printing apparatus according to the first aspect, a peeling claw for peeling the printing base paper is arranged in the vicinity of the cylindrical plate cylinder, and the peeling claw is a cylindrical plate. It is characterized in that it is fixed in a direction in which a peeling position is always obtained with respect to the peripheral surface of the body.

[0016]

According to the present invention, the clamping mechanism forming the convex portion does not exist on the peripheral surface of the cylindrical plate cylinder. That is, the leading end of the printing base paper is inserted into the open portion when the movable portion of the overlapping portion provided on the cylindrical plate cylinder is separated from the fixed portion, and the flexing force of the movable portion released. It is clamped by the fixed part. Therefore, on the peripheral surface of the cylindrical plate cylinder, since the front end clamping portion of the printing base paper has a clamp structure that can open and close a part of the plate cylinder in the circumferential direction in the radial direction, a special convex portion is formed on the surface. Not done.

Further, according to the present invention, in response to a force in the direction in which the printing base paper is pulled when the press roller comes into contact with the cylindrical plate cylinder during printing, the printing base paper is overlapped by the holding pressure at the holding position. It is prevented from coming off.

Further, according to the present invention, the sandwiching portion of the printing base paper can be constituted by a part of the plate cylinder itself in the circumferential direction. Therefore, since there is no projecting member on the surface of the plate cylinder, the tip of the peeling claw used for peeling the printing base paper can be brought close to the peripheral surface of the plate cylinder, and the winding due to sticking of the printing base paper is more effective. Can be prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing the structure of the main part of the present invention. In FIG. 1, the plate cylinder 1 is not shown in detail, but is in the range corresponding to the peripheral portion of the printing base paper winding. A metal plate having a large number of holes and serving as an ink passage portion is used as a base, and a forward and backward rotatable cylindrical member having an ink transmission structure in which a screen layer made of, for example, polyester fiber is arranged on the outer surface thereof. It is configured, and the overlapping portion 1A is provided in a part in the circumferential direction. The overlapping portion 1A has a characteristic configuration in this embodiment, and the peripheral wall of the plate cylinder 1 is divided into the divided one 1A.
1 is positioned on the circumference of the plate cylinder 1 with a regular diameter, and the other divided 1A2 has a circumference longer than the divided position and has the same diameter as the diameter of the plate cylinder 1
The tip is located inside A1. ◆ Therefore, the other divided 1A2 is the divided one 1A
Since the diameter is reduced at the position facing 1,
It stores the bending force to return to the regular diameter. In addition, the other divided 1A2 is divided into one by the bending force.
This means that they are given the habit of sticking to the inside of A1.

On the other hand, an ink supply unit 2 is arranged inside the plate cylinder 1, and the ink supply unit 2 approaches the inner peripheral surface of the plate cylinder 1 or comes into contact with the ink and is interlockable with the plate cylinder 1. The supply roller 2A and the doctor roller 2B fixed in close proximity to the ink supply roller 2A with a predetermined gap.
It has and. In this ink supply unit 2, for example, ink ejected from an ink supply pipe 2C provided on a support shaft 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. Then, after kneading by both of these rollers, the kneaded ink is conveyed by the ink supply roller 2A to a position where this and the plate cylinder 1 face each other.

In the vicinity of the peripheral surface of the plate cylinder 1, a press roller 3 is arranged at a position facing the ink supply roller 2A across the plate cylinder 1, and a peeling claw 4 is arranged behind the press roller 3. Has been done. In the press roller 3, since the clamp portion of the printing base paper is constituted by the peripheral surface of the plate cylinder,
A slight stroke with respect to the surface of the plate cylinder 1 (symbol S in the drawing
(Distance indicated by) is set so that it can be contacted and separated,
The plate cylinder 1 is separated from the plate cylinder 1 when it does not face the porous formation area, and moves toward the plate cylinder 1 side when it faces the porous formation area to press the paper against the plate cylinder 1. Is able to. The above-mentioned contact / separation stroke S of the press roller 3 is smaller than the conventional contact / separation stroke S1 shown in FIG. 5 because there is no projecting member on the peripheral surface of the plate cylinder. Further, the peeling claw 4 is fixed with its tip positioned at a position separated from the peripheral surface of the plate cylinder 1 by a predetermined gap. The predetermined gap is an extremely small gap in consideration of the absence of a member corresponding to the clamp mechanism E shown in FIG.

In FIG. 2, at a position facing the plate cylinder 1,
A vacuum device 6 is provided at a position where the printing base paper 5 is fed from a plate making device (not shown). ◆ This vacuum device 6 is provided with a suction unit 6A that can move up and down in the figure, and at the opposite position, the stacking unit 1 of the plate cylinder 1 is provided.
When A is positioned, it descends and sucks one of the overlapping portions 1A 1A1 to ascend.

Next, the operation will be described. During the plate feeding to the plate cylinder 1, the overlapping portion 1A of the plate cylinder 1 faces the feeding position of the printing base paper from the plate making device. Then, in this state, the suction portion 6A of the vacuum device 6 descends, and rises in a state where one of the overlapping portions 1A is suctioned. Therefore, in the overlapping portion 1A, the side sucked by the vacuum device 6 is a movable portion, and the other side facing the movable portion is a fixed portion, and the movable portion is separated from the fixed portion by the vacuum device 6. Therefore, as shown in FIG.
A space is formed because the front end of the printing base paper 5 is sandwiched.

Then, the vacuum device 6 is provided with the printing base paper 5
While a predetermined amount is being fed, it is lowered to release the suction after maintaining the ascending position, and the movable portion corresponding to one 1A1 of the overlapping portion 1A is brought into close contact with the fixed portion corresponding to the other 1A2 for printing. The leading edge of the paper 5 is clamped. Note that the vacuum device 6 releases the suction at the raised position, and stores the bending force when one of the overlapping portions 1A 1A1 is opened, especially when the ascending stroke is small, instead of descending. You may make it contact | adhere to the other 1A2 using it.

When the leading edge of the printing base paper 5 is clamped in this way, for example, the end of clamping is determined by the result of detecting the feeding amount of the printing base paper 5, and at this point the plate cylinder 1 starts to rotate. Therefore, the printing base paper 5 is held on the surface of the plate cylinder by being adhered to the surface of the plate cylinder by the ink that has been let out until it is cut by the plate making apparatus.

When the plate feeding operation is completed, the sheet is fed from a sheet feeding device (not shown) in synchronization with this ending time, and the press roller 3 moves toward the surface of the plate cylinder 1 at this time. The paper and the printing base paper 4 are pressed.

Further, the sheet passing through the press roller 3 is peeled off from the peripheral surface of the plate cylinder by the peeling claw 4.

According to this embodiment, the clamp portion of the printing base paper 5 can be constituted by the peripheral portion of the plate cylinder 1.
It is possible to eliminate a member such as a sandwiching piece that projects from the peripheral surface of the plate cylinder, whereby the tip of the peeling claw 4 can be brought close to the vicinity of the plate cylinder, and the roll-up of paper can be reliably prevented. In addition, since the peeling claw has no member that interferes with the tip, it can be a fixed structure, which simplifies the structure.

The means shown in FIG. 3 can be used as a means for forming a space for separating the movable portion of the overlapping portion from the fixed portion so that the front end of the printing base paper can be caught therein. ◆ The configuration shown in FIG. 3 has a structure in which the other side 1A2 shown in FIG. 1, that is, the portion located on the inner side of the one side 1A1 located on the diameter of the peripheral wall is a movable part (hereinafter, for the sake of convenience, A movable portion is indicated by reference numeral 1A10 and a movable portion is indicated by reference numeral 1A20), and the movable portion 1A20 is pushed inward to secure a space for holding the printing base paper. Therefore, in the case of the example shown in FIG. 3, instead of the vacuum device 6 shown in FIG. 2, an actuating member 7 provided so as to be movable back and forth along a direction in which the movable portion 1A20 can be pushed is arranged. There is. Therefore, the operating member 7 is displaced in the direction of pushing the movable portion 1A20 toward the inside of the plate cylinder 1 at the same operation timing as that of the vacuum device 6 shown in FIG.
0 is separated from the fixed portion 1A10, and when the feeding of the leading edge of the printing base paper is completed, it is displaced toward the outside of the plate cylinder 1 to bring the movable portion 1A20 into close contact with the fixed portion 1A10.

By the way, the printing base paper whose front end is sandwiched by the overlapping portion 1A rotates with the rotation of the plate cylinder 1, but when the press roller 3 is in contact with the plate cylinder 1, the pressing force of the press roller 3 causes It receives a force in a direction to be pulled out from the clamp portion composed of the overlapping portion 1A to some extent.
Therefore, in the present embodiment, in order to prevent the printing base paper 5 from coming off due to such a force from the press roller 3,
It is also possible to employ friction increasing means for increasing frictional coupling in the above-mentioned overlapping portion 1A. That is, as the friction increasing means, for example, there is a structure in which a rubber plate or sand paper having a high friction coefficient is attached to the overlapped portion, or a large number of fine protrusions are formed. Such a friction increasing means is, for example, when the printing base paper 5 has a structure in which a film is laminated on a base material, by providing the friction increasing means on the surface facing the film surface in the overlapping portion, It is possible to improve frictional coupling with the polymerized portion.

As a method of preventing the printing base paper from slipping off, for example, as shown in FIG. 4, the leading end 5A of the printing base paper 5 is configured so that the leading end 5A is one of the overlapping portions 1A 1A.
It may be folded back at one end portion and arranged between the other overlapping portion 1A2 of the overlapping portion 1A1 located inside.

[0033]

As described above, according to the present invention, the front end sandwiching portion of the printing base paper can be constituted by the peripheral wall of the plate cylinder. That is, by forming a superposed portion by dividing a part of the peripheral wall, the front end of the printing base paper can be caught in the superposed portion. Therefore, a part of the peripheral wall of the plate cylinder
Since it is configured as a clamp mechanism that has been used in the past, it is possible to use an extremely simple structure for the clamping mechanism for the printing base paper. Moreover, since the conventional clamp mechanism or the like is not present on the peripheral surface of the plate cylinder, the press roller and the peeling claw can be brought closer to the plate cylinder side because there is no interference with this mechanism. Therefore, the impact sound can be reduced by reducing the contact / separation stroke of the press roller, and the bounce of the press roller can be prevented by eliminating the step from the peripheral surface of the plate cylinder in combination with the phenomenon of the stroke. Therefore, it is possible to prevent the occurrence of unevenness in image density and obtain stable image characteristics.

Further, according to the present invention, it is possible to prevent the printing base paper from slipping out by providing the friction increasing means in the above-mentioned overlapping section or by folding the printing base paper at the overlapping section. You can
As a result, it becomes possible to prevent printing defects from occurring.

According to the present invention, the clamp mechanism protruding on the peripheral surface of the plate cylinder can be eliminated, whereby the tip positions of the peeling claws facing the plate cylinder are extremely close to each other, and Since it can be fixed at the position, the structure can be simplified by eliminating the contact / separation mechanism that is conventionally used.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram showing a configuration for forming a sandwiching space for a printing base paper used in the main part configuration shown in FIG.

FIG. 3 is a schematic diagram showing a modified example of the configuration for forming a space for inserting the printing base paper shown in FIG.

FIG. 4 is a schematic diagram showing a structure for preventing a printing base paper sheet from coming off in a printing apparatus according to the present invention.

FIG. 5 is a schematic diagram showing a conventional example around a plate cylinder portion in a printing apparatus.

[Explanation of symbols]

 1 plate cylinder 1A overlapping part 1A1 fixed part consisting of one of the divided overlapping parts 1A2 movable part consisting of the other of the divided overlapping parts 3 press roller 4 peeling claw 5 printing base paper 6 vacuum device 7 operating member

Claims (4)

[Claims] 1. A cylindrical porous plate cylinder which is rotatable, wherein a printing base paper perforated on the cylindrical plate cylinder is wound, and a paper is pressed against the cylindrical plate cylinder by a pressing member composed of a press roller. In the printing apparatus for performing printing by the above, the overlapping portion is provided in the circumferential direction of the cylindrical plate cylinder, one of the overlapping portions is a fixed portion, and the other is a movable portion that can be brought into contact with and separated from the fixed portion. A printing apparatus, wherein a printing base paper is sandwiched between overlapping portions by a bending force generated when the movable portion is moved in a direction away from the fixed portion. 2. The printing apparatus according to claim 1, wherein friction increasing means is provided at a position facing the printing base paper sandwiched by the overlapping portion of the cylindrical plate cylinder. 3. The printing apparatus according to claim 1, wherein the printing base paper is sandwiched in a state where the leading end of the printing base paper is folded back to one of the overlapping portions and then wound around a cylindrical plate cylinder. Printing device. 4. The printing apparatus according to claim 1, wherein a peeling claw for peeling the printing base paper is arranged in the vicinity of the cylindrical plate cylinder, and the peeling claw is arranged on the peripheral surface of the cylindrical plate cylinder. The printing device is fixed so that the peeling position is always obtained.