JP2001080188A - Stencil printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a breakage of a plate base sheet due to a tensile force generated in the case of drawing a trailing edge of a printing medium from between an inner push roll and a paper cylinder as much as possible. SOLUTION: In the stencil printer comprising a plate cylinder 16 and a paper cylinder 17 substantially approaching to one another and rotatably provided, a stencil base sheet attachably mounted on an outer periphery of a peripheral wall of the cylinder 16, an inner push roll 47 rotatably provided at an inside of the wall and pressed to the inner periphery of the wall to bring a printing sheet 22 passing between a stencil base sheet 15 and bulged at the wall to the outer peripheral side by this pressing force and mounted on the wall and the cylinder 17 into pressure contact with the roll 47 to print the stencil by pressing, the outer peripheral side of the roll 47 and the outer peripheral side of the cylinder 17 are respectively constituted of elastic materials 61, 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner press type stencil printing apparatus in which a printing pressure is applied from an inner peripheral side of a peripheral wall of a plate cylinder.

[0002]

2. Description of the Related Art FIG. 10 is a sectional view of a printing section of a conventional stencil printing apparatus, and FIG. 11 is an enlarged sectional view of a main part thereof. 10 and 11, the printing unit of the stencil printing apparatus is a plate cylinder 100.
And the printing drum 101, and the plate drum 100 and the printing drum 101 are provided rotatably in a state in which a part of the outer peripheral surface is substantially close to each other. The plate cylinder 100 has a pair of cylindrical flanges (not shown) provided facing each other, and a stencil paper clamp portion 100a for clamping the leading end of the stencil paper 104 is provided on a part of the outer peripheral surface of the flange. ing.
A flexible screen 102 is stretched over the outer peripheral surface of the flange of the plate cylinder 100 other than the base paper clamp portion 100 a, and the screen 102 is configured to pass the ink 103. The outer peripheral surface side of the paper cylinder 101 is formed of a rigid body.

[0003] Inside the plate cylinder 100, an intermediate press roll 106 is provided.
Is arranged. The intermediate pressing roll 106 is rotatably provided on a roll support member 107, and the roll support member 107 is rotatably supported by a fixed member (not shown) about a support shaft 108. The middle press roll 106 is
A pressing position where the roll support member 107 is urged in the direction of arrow a in FIG. 11 to press against the inner peripheral surface of the screen 102, and the roll support member 106 is rotated in the direction of arrow b in FIG. It is configured to be movable between a standby position and a standby position separated from the standby position. The middle press roll 106 is at a pressing position during printing, and is at a standby position except during printing.

[0004] The roll support member 107 is provided with a doctor roll 109 and a drive rod 110, respectively.
As a result, a predetermined ink 103 is attached to the outer peripheral surface of the intermediate pressing roll 106.

Next, the general operation of printing will be described in order. A plate is formed by forming a hole in a predetermined portion of the stencil sheet 104, and the leading end of the stencil sheet 104 thus clamped is clamped.
It is mounted on the outer peripheral surface of the screen 102 forming the peripheral wall of No. 0. Next, the plate cylinder 100 and the paper cylinder 101 are synchronously rotated in the directions indicated by arrows in FIG. During printing, the middle press roll 106 presses the screen 102, and in this pressed state, the middle press roll 106 rotates following the plate cylinder 100. The ink 103 is supplied to the outer peripheral surface of the rotating middle press roll 106, and the attached ink 103 is sequentially transferred to the inner peripheral surface of the screen 102.

In such a state, as shown in FIG. 10, a printing paper 111 is transported between the plate cylinder 100 and the paper cylinder 101.
The rotation is continued by one rotation. And plate cylinder 1
The printing paper 111 that has been conveyed between the printing press 111 and the printing drum 101 is moved between the intermediate press roll 106 and the printing drum 101 by the screen 1.
02 and the stencil sheet 104 while being pressed. By this pressing force, the ink on the screen 102 side is transferred from the hole of the stencil sheet 104 to the printing paper 111 side,
Printing corresponding to the stencil making of the stencil sheet 104 is performed.

[0007]

However, in the above-mentioned conventional stencil printing apparatus, in the course of the above printing operation, as shown in FIG.
02, the pressing force F causes the screen 102 to swell to the outer peripheral side of the plate cylinder 100, and the swelled screen 10
The printing pressure acts on the stencil paper 104 and the printing paper 111 by receiving the pressing force F acting on the stencil paper 104 and the printing paper 111 on the paper cylinder 101 via the stencil paper 104 and the printing paper 111. Therefore, as shown in FIG. 13A, at the point where the rear end of the printing paper 111 comes out from between the intermediate press roll 106 and the paper cylinder 101, stress is applied to the stencil sheet 104 corresponding to the rear end of the printing paper 111. As the printing paper 111 is concentrated and the rear end of the printing paper 111 comes off, the screen 102 and the stencil sheet 104 are further swelled to the outer peripheral side by the pressing force F of the intermediate pressing roll 106 and are shifted so as to be pressed against the paper cylinder 101. In other words, the stencil sheet 104 is fixed at that portion by the concentration of stress, and the vicinity thereof is moved toward the paper cylinder 101, whereby a tensile force acts. Since such a tensile force is generated at the same position when the stencil sheet 104 is the same, there is a problem that the stencil sheet 104 is broken by printing a large number of sheets and printing failure occurs.

The magnitude of the pulling force is determined by the printing paper 111
Depends on the thickness. That is, the displacement amount D1 of the screen 102 and the stencil sheet 104 toward the paper cylinder 101 when the rear end of the printing paper 111 comes out from between the intermediate press roll 106 and the paper cylinder 101 is as shown in FIG. Stencil paper 10
4 and the paper cylinder 101.

Therefore, the thicker the printing paper 111 is, the larger the displacement amount D1 of the stencil sheet 104 is and the greater the tensile force is. And, the thicker the printing paper 111 is, the higher the probability that the stencil paper 104 is torn is increased, and it is desired to improve the probability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is an object of the present invention to tear a stencil sheet due to a tensile force generated when a rear end of a print medium comes out from between a middle press roll and a paper cylinder. It is an object of the present invention to provide a stencil printing apparatus capable of preventing stencil printing as much as possible.

[0011]

According to a first aspect of the present invention, a plate cylinder and a paper cylinder are rotatably provided with a part of their outer peripheral surfaces substantially close to each other, and a stencil sheet is provided on the outer peripheral surface of the peripheral wall of the plate cylinder. Is provided so as to be freely attachable, and a middle press roll is provided inside the peripheral wall,
This intermediate press roll is provided so as to be able to press on the inner peripheral surface of the peripheral wall, and during printing, the plate cylinder and the paper cylinder are rotated so that the substantially adjacent outer peripheral surfaces move in the same direction, and the intermediate press roll is pressed against the peripheral wall. Pressing against the inner peripheral surface, the peripheral wall swells to the outer peripheral side by this pressing force, and presses the printing medium passing between the stencil paper attached to the peripheral wall and the paper cylinder, thereby performing press-type printing. Wherein the outer peripheral surface of the intermediate press roll and the outer peripheral surface of the paper cylinder are each formed of an elastic body.

In this stencil printing apparatus, stress is concentrated on the stencil sheet corresponding to the rear end of the print medium at the point where the rear end of the print medium comes out from between the intermediate press roll and the paper cylinder,
Further, as the rear end of the print medium comes off, the screen and the stencil sheet further swell to the outer peripheral side by the pressing force of the intermediate press roll and are displaced so as to press against the paper cylinder, but the outer peripheral side of the intermediate press roll and the paper cylinder together. Since the elastic body is compressed by elastic deformation at a place where the print medium abuts, but is not compressed at other places, the displacement amount of the stencil sheet to the paper cylinder side is smaller than the thickness of the print medium. It is sufficiently small that no large tensile forces act on the print medium.

[0013]

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

1 to 9 show an embodiment of the present invention.
1 is a schematic configuration diagram of a stencil printing apparatus, FIG. 2 is an exploded perspective view of an inner press mechanism, FIG. 3 is a perspective view of an inner unit, and FIG. 5 is a side view of the inside of the plate cylinder where the middle press roll is at the pressing position, FIG. 6 is a side view of the inside of the plate cylinder showing the state where the middle press roll is at the press position, and avoids the base paper clamp section, and FIG. FIG. 8 is a cross-sectional view of a main part of the printing drum, showing a supply state and the like of the printing drum.

In FIG. 1, a stencil printing apparatus 1 is mainly composed of a document reading unit (not shown), a stencil making unit 3, a printing unit 4, a paper feeding unit 5, a paper discharging unit 6, and a stencil discharging unit 7. I have.

A document reading unit (not shown) reads a document as an electric signal. The read information can be processed based on a predetermined command (enlargement, reduction, etc.).

The plate-making section 3 includes a rolled long base paper 10.
And a thermal head 12 disposed downstream of the long paper 10 in the transport direction of the long paper 10 with respect to the raw paper housing 11, and a write pulse motor (see FIG. The platen roller 13 is rotated by a driving force of a not-shown), and is disposed downstream of the platen roller 13 and the thermal head 12 in the transport direction of the elongate base paper 10 and is rotated by a driving force of a write pulse motor (not shown). A pair of base paper feed rollers 14, and a base paper cutter (not shown) disposed between the pair of base paper feed rollers 14, the platen roller 13 and the thermal head 12.

The printing unit 4 includes a plate cylinder 16 and a paper cylinder 1 having substantially the same diameter.
The plate cylinder 16 and the paper cylinder 17 are provided so as to be rotatable with their outer peripheral parts partially close to each other. The plate cylinder 16 has a pair of cylindrical flanges provided to face each other, and a base paper clamp 18 is provided on a part of the outer peripheral surface of the flange.
At 8, the leading end of the stencil sheet 15 can be clamped. The plate cylinder 1 is provided on the outer peripheral surface of the flange of the plate cylinder 16 other than the base paper clamp portion 18.
A flexible screen 19 which forms the peripheral wall of No. 6 is stretched. Screen 19 forming the peripheral wall of the plate cylinder 16
Is configured to be able to pass through the ink 53 when a printing pressure is applied at least in a printing area. An inner press roll 47 of the inner press mechanism 20 is provided inside the screen 19 forming the peripheral wall of the plate cylinder 16, and the inner press mechanism 20 will be described in detail below.

The outer circumference of the paper cylinder 17 basically has a circumferential surface shape, but is formed as a cutout portion 17a partially cut out. When the plate cylinder 16 and the paper cylinder 17 are rotated synchronously or only the plate cylinder 16 is rotated, the notch portion 17a
And does not interfere with the stencil clamp portion 18.
As shown in detail in FIG. 8, a paper clamp 21 is provided in the notch 17a of the paper cylinder 17, and the paper clamp 2
Reference numeral 1 denotes a clamp cover 21a fixed to the paper cylinder 17 and a clamper 21b rotatably mounted on the clamp cover 21a. The clamper 21b is configured to clamp a leading end of a printing paper 22 as a print medium. ing. An elastic body 60 is provided on the outer circumferential surface of the paper cylinder 17 in the form of a circumferential surface.
Is provided, and the outer peripheral surface side of the paper cylinder 17 is formed of an elastic body 60. The material of the elastic body 60 is nitro-butadiene rubber, urethane, or the like, and a material that is durable with respect to ink or the like is preferable.

The paper supply unit 5 includes a printing paper 22 as a printing medium.
, A scraper 24 that presses the printing paper 22 at the highest position from the paper feeding table 23, and a pickup roll 25 that is disposed downstream of the scraper 24 and that is positioned substantially in proximity to each other. And a roll 26, and a guide roll 27 and a timing roll 28 which are arranged downstream of the pickup roll 25 and the roll 26 and are located substantially in proximity to each other. The printing paper 22 moved by the rotation of the scraper 24 includes a pickup roll 25 and a sabaki roll 26.
Is allowed to convey only the printing paper 22 at the uppermost position.
By the rotation of the timing roll 28 and the timing roll 28, the sheet is conveyed in synchronization with the rotation of the paper cylinder 17.

The paper discharge unit 6 is a printing paper 22 on which printing has been completed.
Upper regulation guide portion 30 for guiding the leading end of
A paper stripping claw 32 for stripping the printing paper 22 that is not stripped from the paper, a paper transport mechanism 33 for transporting the printing paper 22 guided by the upper regulation guide portion 30 or peeled off by the paper stripping claw 32; And a stacker section 34 on which the printing paper 22 transported by the paper transport mechanism 33 is placed in a stacked state.

The plate discharging section 7 is a base paper clamp section 1 of the plate cylinder 16.
A stencil guide belt 35 for guiding the leading end of the stencil sheet 15 released from the stencil 8, a pair of stencil conveyance belts 36 for conveying the stencil sheet 15 guided by the stencil guide belt 35 while peeling it off from the plate cylinder 16, Plate conveyor belt 3
And a stencil discharge box 37 for accommodating the stencil sheet 15 conveyed by the stencil 6.

2 to 6, the inner press mechanism 20 includes an inner unit 3 disposed inside the plate cylinder 16.
8 and the inner unit 3 arranged outside the plate cylinder 16.
8 has a power transmission means 39 for transmitting a rotational force. The inner unit 38 has a roll support member 40, which is rotatably supported by a fixed member (not shown) about a support shaft 41. A tooth portion 42 is provided on the roll support member 40, and the tooth portion 44 of the inner arm portion 43 meshes with the tooth portion 42. The inner arm 43 is rotatably supported on a drive shaft 43a as a fulcrum. One end of the drive shaft 43a is
Projecting outside. The drive shaft 43 protruding to the outside
The rotational force from the power transmission means 39 is transmitted to a.

When the inner arm 43 rotates clockwise in FIGS. 4 to 6, the roll support member 40 rotates counterclockwise, and the intermediate pressing roll 47 described below moves
When the inner arm 43 is rotated in the counterclockwise direction in FIGS. 4 to 6, the roll is supported. The member 40 rotates clockwise to rotate the middle pressing roll 4.
The standby position where the camera 7 exits inside the screen 19 (FIG. 4)
(State shown in the figure).

A gear 45 is rotatably supported on the support shaft 41, and the gear 45 meshes with an inner peripheral gear 46 of the plate cylinder 16. An intermediate press roll 47 is rotatably supported by the roll support member 40, and the outer peripheral surface side of the intermediate press roll 47 is configured as an elastic body 61 such as rubber (shown in FIG. 7 and the like). A first gear 48 and a roller member 49 are fixed to both ends of the shaft of the intermediate press roll 47, respectively. The first gear 48 meshes with the gear 45 of the support shaft 41, and the intermediate press roll 47 is rotated in synchronization with the rotation of the plate cylinder 16. Further, the roller member 49 is located at a position separated from the flange cam surface 50 of the plate cylinder 16 at the standby position of the intermediate pressing roll 47, and at the pressing position, at the flange cam surface 5 of the plate cylinder 16.
The intermediate press roll 47 is moved up and down along the flange cam surface 50 at the press contact position.

The flange cam surface 50 has a large diameter range, a small diameter range, and an inclined range in which the diameters are continuous from the center of rotation. At the base paper clamp portion 18, the diameter from the rotation center is configured in a small diameter size range, and the roller member 49 of the inner unit 38 is pressed against the flange cam surface 50 and is regulated by the flange cam surface 50, so that the intermediate pressing roll is formed. 47 is the base paper clamp unit 18
The base paper clamp 18
Is passed, the roller member 49 of the inner unit 38 is separated from the flange cam surface 50, and the intermediate press roller 47 returns to the position where the screen 19 is pressed, and the base paper clamp portion 18
, The roller member 49 of the inner unit 38 is pressed against the flange cam surface 50, and is regulated by the flange cam surface 50, so that the intermediate pressing roll 47 causes the screen 19.
Gradually away from In other words, the roller 49 and the flange cam surface 50 of the inner unit 38 are set so that the pressing start position and the pressing release position of the middle pressing roll 47 against the screen 19 are at predetermined positions.

The power transmission means 39 is, as shown in FIG.
A motor 72, which is a driving source, is fixed to a fixing member 70 outside the plate cylinder 16 via a bracket 71. A worm gear 73 is fixed to a rotating shaft of the motor 72, and a disk for detecting a rotational position is provided. 74 is fixed. A rotation position detection sensor 7 is provided on the outer periphery of the rotation position detection disk 74.
5 are provided close to each other, and are configured to be able to control the stroke of a spring 79 described below and, consequently, the printing pressure of the middle press roll 47 based on the detection output of the rotation position detection sensor 75.

A worm wheel 77 meshes with the worm gear 73, and a flat gear 76 is integrally fixed to the worm wheel 77. This spur gear 76
The teeth 78a of the arm member 78 mesh with the arm member 78, and the arm member 78 is rotatably supported about a support shaft 79. A spring hook pin 78b is fixed to the other end of the arm member 78 opposite to the tooth portion 78a, and one end of a spring 79 is hooked to the spring hook pin 78b. Further, the spring catching pin 78b is connected to the link plate 8 as a link member.
The spring engaging pin 78b and the link plate 80 are prevented from being separated by the screw 81 and the washer 82. The other end of the spring 79 and the other end of the link plate 80 are locked to the outer arm 83 by screws 84 and washers 85. The outer arm portion 83 is fixed to a circumferential outer surface of the rotation support 86, and the rotation support 86 is provided with an engagement hole (not shown) for engaging with the drive shaft 43a. The rotation of the rotary support 86 is transmitted to the drive shaft 43a by inserting the drive shaft 43a into the engagement hole.

When the arm member 78 is rotated in the clockwise direction (the direction of the arrow a in FIG. 2) by the driving of the motor 72, the outer arm 83 is rotated in the counterclockwise direction (c in FIG. (In the direction of the arrow), and the intermediate pressing roller 47 is positioned at the pressing position shown in FIGS. 5 and 6. The pressing force by the spring force of the spring 79 always acts on the intermediate pressing roll 47 at the pressing position, and this is the printing pressure. Further, the arm member 78 is rotated clockwise by the drive of the motor 72 (FIG. 2).
When the spring hooking pin 78b presses the bottom end surface of the long groove 80a of the link plate 80, the link plate 80 presses the outer arm 83, and the outer arm 83 rotates clockwise (see FIG. 2 d arrow direction)
, And the intermediate press roll 47 is positioned at the standby position shown in FIG. In other words, the link plate 80 acts to transmit the driving force in the direction in which the middle press roller 47 is shifted from the pressing position to the standby position, and the spring 79 acts in the direction to shift the middle press roller 47 from the standby position to the pressing position. Transmit power.

As shown in FIGS. 3 and 7, the roll supporting member 40 has a doctor roll 51 and a driving rod 52.
Are provided respectively. The doctor roll 51 is fixed to the roll support member 40 at a position close to the middle press roll 47. The drive rod 52 is rotatably supported by the roll support member 40, and is disposed in an upper space defined by the outer peripheral surfaces of the middle press roll 47 and the doctor roll 51 on the side close to each other. The ink 53 is supplied to the upper space from an ink supply unit (not shown). A gear 54 is fixed to one end of the drive rod 52, and the gear 54 meshes with a second gear (not shown) of the intermediate press roll 47. The second gear (not shown) is supported on the shaft of the intermediate press roll 47 via a one-way clutch (not shown), and the drive rod 52 rotates in conjunction with the rotation of the plate cylinder 16 similarly to the above-described intermediate press roll 47. Is done.

When the ink 53 is supplied to the upper space from an ink supply unit (not shown), the ink 5
3 is agitated by the drive rod 52, and the ink 53 adhering to the outer peripheral surface of the intermediate press roll 47 among the agitated inks 53 has the intermediate press roll 47 due to its adhesiveness.
Try to rotate together with the rotation of. Then, only a predetermined amount of the ink 53 continues to be adhered by passing through the gap with the doctor roll 51, and the middle press roll 47 is pressed against the screen 19 downstream of the doctor roll 51. It is transferred to the inner peripheral surface of the screen 19. That is, the middle press roll 4
Reference numeral 7 has a function of applying a printing pressure from the inner peripheral side of the screen 19 and a function of supplying the ink 53 to the screen 19.

As shown in FIGS. 4 to 6, a pair of left and right ink scraping members 62 are provided on the downstream side of the rotation of the screen 19 with respect to the intermediate press roll 47 and inside the screen 19. Each of the ink scraping members 62
The lower end is pressed against both ends of the screen 19 while being urged by urging means such as a spring, and is inclined in a direction to return the ink 53 flowing out to both ends to the center of the screen 19.

Next, the operation of the stencil printing machine 1 will be briefly described. In the plate making section 3, the long base paper 10 is conveyed by the rotation of the platen roller 13 and the base paper feed roller 14, and each heating element of the thermal head 12 is selectively operated based on image information read by a document reading section (not shown). The perforated sheet 15 is cut by a stencil cutter (not shown) to produce a perforated sheet on the long stencil 10 by the heat-generating operation.

In the printing section 4, the leading end of the stencil sheet 15 produced by the stencil section 3 is clamped by the stencil clamping section 18 of the plate cylinder 16, and in this clamped state, the plate cylinder 16 is rotated to convert the stencil sheet 15 to the stencil sheet. Screen 1 forming the peripheral wall of body 16
9 Wrap and attach to the outer peripheral surface.

The paper supply unit 5 conveys the printing paper 22 in synchronization with the rotation of the plate cylinder 16 and the paper cylinder 17, and clamps the leading end of the printing paper 22 by the paper clamping unit 21 of the paper cylinder 17. And between the paper cylinder 17.

On the other hand, in the printing section 4, the middle press roll 47 is set to the standby position shown in FIG. 4 except during printing.
Rotate 6. Then, as shown in FIG. 5, the middle press roll 47 presses the inner peripheral side of the screen 19 except for the avoidance position shown in FIG. 19 rotates on the inner peripheral surface. Since the ink 53 is continuously supplied to the outer peripheral surface of the intermediate press roll 47, the ink 53 is transferred to the screen 19 by this rotation. or,
The screen 19 is swelled to the outer peripheral side by the pressing of the intermediate pressing roll 47, and is brought into pressure contact with the paper cylinder 17. Then, as described above, the printing paper 22 is conveyed from the paper feeding unit 5 between the plate cylinder 16 and the paper cylinder 17, and the conveyed printing paper 2
2 is a screen 1 between the intermediate press roll 47 and the paper cylinder 17.
9 and the stencil sheet 15 are conveyed while being pressed.
In this pressing and conveying process, the ink 53 is transferred from the perforated portion of the stencil sheet 15 to the printing paper 22 and an image is printed. When the leading end of the printing paper 22 passes through the position of the intermediate press roll 47 and reaches downstream thereof, the paper clamp unit 21 is released.

In the paper discharge section 6, the leading end of the printing paper 22 is guided by the upper regulation guide section 30, or the leading end of the printing paper 22 is peeled off from the paper cylinder 17 by a paper peeling claw 32. The sheet is conveyed to the stacker 34 via the conveying mechanism 33.

Further, in the plate discharging section 7, when starting a new plate making, it is necessary to discharge the used stencil sheet 15 used for the previous printing wound around the screen 19 of the plate cylinder 16 and mounted. However, in this case, the stencil sheet clamping unit 18 of the plate cylinder 16 is released before the new stencil sheet having been made on the outer peripheral surface of the screen 19 of the plate cylinder 16 is released. The leading end is guided by a plate discharge guide belt 35 while rotating the plate cylinder 16, and is conveyed by a pair of plate discharge conveyance belts 36 and stored in a plate discharge box 37.

In the above-described printing operation, the intermediate press roll 47 presses the screen 19, and the pressing force F causes the screen 19 to bulge to the outer peripheral side of the plate cylinder 16. The printing pressure acts on the stencil sheet 15 and the printing paper 22 by receiving the pressure F by the paper cylinder 17 via the stencil sheet 15 and the printing paper 22. Accordingly, as shown in FIG. 9A, at the point where the rear end of the printing paper 22 comes out from between the intermediate press roll 47 and the paper cylinder 16, stress is applied to the stencil sheet 15 corresponding to the rear end of the printing paper 22. The screen 19 and the stencil sheet 15 are further swelled to the outer peripheral side by the pressing force F of the intermediate pressing roll 47 and moved so as to be pressed against the paper cylinder 17 as the printing paper 22 is concentrated and the rear end of the printing paper 22 comes off. As a result, the stencil sheet 15 is fixed at that portion by stress concentration, and the stencil sheet 15 is
By moving to the 7 side, a tensile force acts.

Here, the outer peripheral surfaces of the intermediate press roll 47 and the paper cylinder 17 are both constituted by elastic bodies 61 and 60, and FIG.
As shown in (B), since the printing paper 22 abuts against each other due to elastic deformation but is not compressed at other locations, the displacement D2 of the stencil sheet 15 toward the paper cylinder 17 is given by The thickness is sufficiently smaller than the thickness t of the printing paper 22, and no large tensile force acts on the printing paper 22. Accordingly, tearing of the stencil sheet 15 due to the tensile force generated when the rear end of the printing paper 22 comes off from between the intermediate press roll 47 and the paper cylinder 17 can be prevented as much as possible.

Further, as described above, the intermediate pressing roll 47
At the point where the rear end of the printing paper 22 comes out from between the paper cylinder 17 and the paper cylinder 17, stress concentrates on the stencil sheet 15 corresponding to the rear end of the printing paper 22, but in the present invention, the outer peripheral surface side of the paper cylinder 17 is elastic. Since it is composed of the body 60, FIG.
As shown in FIG. 2B, since the portion of the paper cylinder 17 corresponding to the rear end of the printing paper 22 is also compressed and deformed, the level of the stress concentration is reduced as compared with the conventional example, and the stencil sheet 15 is prevented from being broken. To serve.

In particular, in the conventional example, when the thickness of the printing paper 22 is large, there is a high possibility that the stencil sheet 15 is broken.
In the present invention, since the displacement amount D2 of the stencil sheet 15 can be made sufficiently smaller than the thickness t of the printing paper 22 and the tensile force can be weakened, the possibility that the stencil sheet 15 can be broken can be made sufficiently small to cause no practical problem. .

According to the above-described embodiment, the inner press mechanism 20 is configured so that the pressing force of the middle press roll 47, that is, the printing pressure, can be changed by changing the stroke of the spring 79. In a device capable of varying the printing pressure in this manner, in the related art, the tensile force acting on the stencil sheet 15 increases in proportion to the printing pressure, but in the present invention, when the pressing force of the intermediate pressing roll 47 increases, the paper pressure increases. Body 1
7, the compression deformation of the stencil sheet 15 increases,
Conversely, the shift amount D2 to the side becomes smaller. Therefore, in an apparatus capable of changing the printing pressure, the intermediate pressing roll 47 and the cylinder 1
7, it is not necessary to limit the set level of the printing pressure in consideration of the tear of the stencil sheet 15 caused by the tensile force generated when the rear end of the printing paper 22 comes off from the gap between the printing pressure and the printing pressure.

[0044]

As described above, according to the first aspect of the present invention, the plate cylinder and the paper cylinder are provided rotatably with their outer peripheral parts being substantially close to each other, and the stencil is provided on the outer peripheral surface of the plate cylinder. A base paper is provided so as to be freely attached, ink is supplied from the inner peripheral surface side of the peripheral wall, and an intermediate pressing roll is provided inside the peripheral wall, and the intermediate pressing roll is pressed against the inner peripheral surface of the peripheral wall, and the pressing force causes the peripheral wall to move toward the outer peripheral side. A stencil printing apparatus that performs stencil printing in a pressurized manner by pressing a stencil sheet mounted on a peripheral wall and a printing medium passing between the paper cylinders in a press-fit manner, wherein Since the outer peripheral side of the paper cylinder is made of an elastic body, stress is applied to the stencil sheet corresponding to the rear end of the print medium at the point where the rear end of the print medium comes out from between the intermediate press roll and the paper cylinder. Focus on the print media as the trailing edge The peripheral wall and the stencil sheet are further expanded to the outer peripheral side by the pressing force of the intermediate press roll and displaced so as to press against the paper cylinder, but the outer peripheral surfaces of the intermediate press roll and the paper cylinder are both elastic bodies, and the portion where the print medium comes in contact In this case, the two members are compressed by elastic deformation but are not compressed in other portions.Therefore, the above-mentioned displacement amount is sufficiently smaller than the thickness of the print medium, and a large tensile force is not applied to the print medium. Of the stencil sheet due to the tensile force generated when the trailing edge of the printing medium comes off from between the paper and the paper cylinder.

[Brief description of the drawings]

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

FIG. 2 is an exploded perspective view of the inner press mechanism, showing one embodiment of the present invention.

FIG. 3 is a perspective view of the inner unit according to the embodiment of the present invention.

FIG. 4 is a side view showing the inside of the plate cylinder in which the intermediate press roll is at a standby position, according to the embodiment of the present invention.

FIG. 5 is a side view of the inside of the plate cylinder in which the middle press roll is at the pressing position, according to the embodiment of the present invention.

FIG. 6 is a side view of the inside of the plate cylinder showing the embodiment of the present invention and showing a state where the middle press roll is in the pressing position and avoids the base paper clamp portion.

FIG. 7 is a side view of the inside of the plate cylinder showing an ink supply state and the like according to the embodiment of the present invention.

FIG. 8 is an enlarged sectional view of a main part of a paper cylinder, showing an embodiment of the present invention.

FIG. 9 shows an embodiment of the present invention, in which (A) is a cross-sectional view showing a state in which a middle press roll presses an end of a printing sheet;
FIG. 9B is a cross-sectional view in which a part of FIG.

FIG. 10 is a cross-sectional view of a printing unit of a stencil printing machine, showing a conventional example.

FIG. 11 shows a conventional example and is an enlarged sectional view of a main part of a printing section of a stencil printing apparatus.

FIG. 12 is a cross-sectional view showing a conventional example, showing a state where a middle press roll presses a paper cylinder.

13A and 13B are cross-sectional views illustrating a conventional example, in which FIG. 1A is a cross-sectional view illustrating a state in which an intermediate pressing roller presses an edge of a printing sheet, and FIG.
It is the line sectional view to which a part of 3 (A) was expanded.

[Explanation of symbols]

 15 stencil paper 16 plate cylinder 17 paper cylinder 19 screen 22 printing paper (printing medium) 47 medium press roll 53 ink 60, 61 elastic body

Claims (1)

[Claims] 1. A printing drum and a paper cylinder are rotatably provided with a part of their outer peripheral surfaces substantially close to each other, and a stencil sheet is provided on the outer peripheral surface of the peripheral wall of the plate cylinder so as to be freely mounted. An intermediate press roll is provided, and the intermediate press roll is provided so as to be able to be pressed on the inner peripheral surface of the peripheral wall, and at the time of printing, the plate cylinder and the paper cylinder are rotated so that the substantially adjacent outer peripheral surfaces move in the same direction, and the intermediate press is performed. By pressing the roll against the inner peripheral surface of the peripheral wall, the pressing force causes the peripheral wall to swell to the outer peripheral side and press the printing medium passing between the stencil paper attached to the peripheral wall and the paper cylinder by pressure contact. A stencil printing apparatus for performing stencil printing in a pressurized manner, wherein an outer peripheral surface side of the intermediate press roll and an outer peripheral surface side of the paper cylinder are each formed of an elastic body.