JPH079751A - Screen printing machine - Google Patents

Abstract

PURPOSE:To enhance the rising properties at the time of re-printing by setting the sum of the volumes of the perforations of a support layer, the open area of a mesh screen layer and the voids of a base layer to a specific ratio or less with respect to the volume of the ink supplied to the inner peripheral surface of a plate cylinder during one revolution of the plate cylinder. CONSTITUTION:In performing printing in such a state that the master 4 for a thermal screen plate perforated by a thermal head is wound around a plate cylinder 100, the plate cylinder 100 is constituted of a two-layered structure consisting of a porous cylindrical support layer 1 forming an inner peripheral surface and a mesh screen layer 2 forming an outer peripheral surface and an ink roller 6, a doctor roller 7 and an ink supply pipe 5 are arranged in the plate cylinder 100. The sum of the volumes of the perforations of the support layer 1, the open area of the mesh screen layer 2 and the voids of the porous flexible base layer of the master 4 in the plate cylinder 100 is set to 84% or less of the volume of the ink supplied to the inner peripheral surface of the plate cylinder 100 during one revolution of the plate cylinder 100 by ink supply devices (5-7).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing machine which prints by winding a master for heat-sensitive stencil punched by a thermal head or the like on a plate cylinder.

[0002]

2. Description of the Related Art Conventionally, a stencil printing machine performs perforation plate making on a master for a heat sensitive stencil by a heating element such as a thermal head, and the master is automatically conveyed to form a porous support layer and a mesh screen layer. Is automatically wrapped around the outer peripheral surface of a cylindrical plate cylinder, and pressing means such as a press roller continuously presses the printing paper against the master, and an opening provided in the plate cylinder and the master Printing is performed by allowing ink to seep out from the perforated portion.

In the stencil printing machine, when printing is restarted after the printer is left unused for a long period of time, the ink on the support layer of the plate cylinder and the mesh screen layer is evaporated, or the ink is deposited on the master support. Since the amount of ink is reduced due to absorption, it is necessary to carry out trial printing on many sheets of paper in order to obtain a good printed image, resulting in waste of paper and loss of time. Therefore, as shown in JP-A-61-188180, means for increasing the contact pressure between the plate cylinder and the ink supply roller is provided.
When printing is started after leaving the apparatus for a long time, the contact pressure of the ink roller to the plate cylinder is increased to increase the ink supply amount to the plate cylinder and improve the start-up at the start of printing. As disclosed in Japanese Laid-Open Patent Publication No. 3-175081, when printing is started after the apparatus has been left for a long time, an unmade master is wound around a plate cylinder, and a pressing member is operated to fill ink. Has been introduced.

[0004]

However, in the method of increasing the contact pressure between the plate cylinder and the ink supply roller, an ink roller which is an ink supply member when the plate cylinder is pressed by a pressing member such as a press roller. Since it is set to be easily deformed so as to come into contact with the surface of the plate cylinder, if it is strongly pressed from the inner peripheral surface of the plate cylinder, it may not be uniformly deformed, and ink unevenness may occur, or if it is weakly pressed, it takes time to supply ink. There is. Further, since the number of members for increasing the contact pressure increases, the weight of the device itself becomes heavy, which causes a problem of cost increase. On the other hand, by winding an unmade master on the plate cylinder,
The method of activating the pressing member to fill the ink has a problem in that when the master of the unmade plate is discharged, a large amount of ink attached to the master of the unmade plate and discarded is wasted.

Therefore, the present invention solves the above-mentioned problems, and even after leaving the stencil printing apparatus for a long period of time without being used, the start-up at the time of reprinting is fast and there is no loss of paper and ink at low cost. An object is to provide a new stencil printing machine.

[0006]

According to the present invention, a master for a heat-sensitive stencil comprising a porous flexible base layer and a thermoplastic resin film layer is wound on the outer peripheral surface, and the ink is applied from the inner peripheral surface. While supplying the ink by the supply device, in a stencil printing apparatus having a plate cylinder that rotates about its rotation center axis, the plate cylinder, a porous cylindrical support layer forming the inner peripheral surface, A mesh screen layer formed by intersecting the fibrous material in a mesh shape to form the outer peripheral surface, the openings of the support layer, the open areas of the mesh screen layer, and the voids of the base layer. The total volume of the ink and the ink is 84% or less of the ink volume supplied to the inner peripheral surface from the ink supply device during one rotation of the plate cylinder.

[0007]

According to the present invention, the volume of ink supplied to the inner peripheral surface of the plate cylinder by the ink supply device during one rotation of the plate cylinder is 84
%, The sum of the volume of the openings of the support layer, the open areas of the mesh screen layer, and the voids of the base layer is set, so that sufficient ink is supplied at the start of printing.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 100 indicates a plate cylinder.
The plate cylinder 100 has a two-layer structure including a porous cylindrical support layer 1 forming an inner peripheral surface and a mesh screen layer 2 forming an outer peripheral surface. The plate cylinder 100 is rotatably supported around a rotation center shaft 5 that also serves as an ink pipe, which will be described later, and is rotated by a motor (not shown).

The support layer 1 is formed of a metal such as stainless steel in a cylindrical shape, and has a clamp means 21 for clamping the master 4 for heat-sensitive stencil on the outer peripheral surface thereof. As shown in FIG. 3, the support layer 1 is provided with a large number of openings 1a for allowing ink to pass therethrough except for the clamping means 21 and its peripheral portion.

As shown in FIG. 4, in the mesh screen layer 2, fibrous materials such as synthetic resin fibers such as tetron and nylon or fibers of stainless steel are crossed in a mesh shape, and ink is applied in the same manner as the support layer 1. A large number of open areas 2a are formed to allow passage.

In FIG. 1, on the upper right side of the plate cylinder 100, a master 4 punched by plate making means (not shown).
A plate feed roller pair 14 for transporting the sheet and a guide plate 15 arranged between the plate feed roller 14 and the clamp means 21 for guiding the master 4 to the clamp means 21 are arranged.

The master 4 is formed by laminating a film layer of a very thin thermoplastic resin such as polyester and a synthetic fiber or Japanese paper as a porous flexible base layer, or a mixture of Japanese paper and synthetic fiber. It has a laminated structure. As shown in FIG. 5, the base layer 19 holds and diffuses the ink by the synthetic fibers, the Japanese paper, or the voids 19a between the Japanese paper and the synthetic fibers. Note that reference numeral 20 indicates a perforation formed by the plate making means described above. Note that only the film layer is shown in FIGS. 1 and 2.

The clamp means 21 is arranged at a stage portion 3 provided along the generatrix of the outer peripheral surface of the support layer 1 and at a portion facing the stage portion 3, and is swingably supported by the clamper shaft 2a. And a clamper 2.

Inside the plate cylinder 100, as shown in FIG. 2, the ink roller 6 for supplying ink to the inner peripheral surface of the support layer 1 and the ink roller 6 are arranged in parallel with a slight gap A therebetween. A doctor roller 7 that forms an ink reservoir 8 with the ink roller 6 and an ink pipe 5 that supplies ink to the ink reservoir 8 are arranged. Here, the ink roller 6, the doctor roller 7, and the ink pipe 5 form an ink supply device 200.

A press roller 9 for pressing the printing paper 13 against the printing cylinder 100 and a registration roller for feeding the printing paper 13 to the pressing roller 9 at a predetermined timing are provided in the vicinity of the lower side of the outer peripheral surface of the printing cylinder 100 facing the ink roller 6. Pairs 12 and 12 are arranged.

In FIG. 1, a plate discharge section 300 is arranged near the left side of the outer peripheral surface of the plate cylinder 100. Plate ejection unit 30
0 is a plate discharge box 18 for accommodating a used master (not shown) separated from the outer peripheral surface of the plate cylinder 100, and a used master (not shown) is separated from the outer peripheral surface of the plate cylinder 100, It has a pair of plate discharge rollers 16 and 17 that are transferred into the inside of the plate 18.

In FIG. 1, a paper discharge section 400 is disposed near the lower right side of the outer peripheral surface of the plate cylinder 100. The paper discharge unit 400 separates the printed paper (not shown) arranged near the paper discharge tray 11 and the plate cylinder 100 on which the printed print paper (not shown) is sequentially stacked from the plate cylinder 100. It has a peeling nail 10.

Next, the operation of this stencil printing machine will be described. In FIG. 1, the plate cylinder 100 includes a clamp means 2
Between the clamper 2 and the stage section 3 of No. 1, the tip of the master 4 punched by the plate making means is held. The master 4 is wound around the outer peripheral surface of the mesh screen layer 2. First, one sheet of printing paper 13 is fed to the registration roller pair 12 by a paper feeding device (not shown), and is wound around the outer peripheral surface of the mesh screen layer 2 at a predetermined timing synchronized with the rotation of the plate cylinder 100 by the registration roller pair 12. The printing paper 13 is placed between the mounted master 4 and press roller 9.
Is inserted. At this time, the ink roller 6 also rotates in the same direction as the rotation direction of the plate cylinder 100. The ink in the ink reservoir 8 is attached to the surface of the ink roller 6 by the rotation of the ink roller 6, and the amount of the ink is regulated when passing through the gap A between the ink roller 6 and the doctor roller 7, and the inner circumference of the support layer 1 is controlled. Supplied to the surface. The ink supplied to the inner peripheral surface of the support layer 1 is further rotated by the ink roller 6 so that the openings 1a of the support layer 1 and the open areas 2 of the mesh screen layer 2 are formed.
It is supplied to the surface of the master 4 that contacts the mesh screen layer 2 through a. Then, the press roller 9 separated from the outer peripheral surface of the plate cylinder 100 moves upward, and the printing paper 13 is pressed by the master 4 wound around the outer peripheral surface of the mesh screen layer 2 of the rotating plate cylinder 100. By
Ink is transferred from the perforated portion of the master 4 to the surface of the printing paper 13 and printed. And the printed printing paper 1
3 is peeled from the outer peripheral surface of the plate cylinder 100 by the peeling claw 10 and discharged to the paper discharge tray 11, and so-called plate-making is completed by printing the first first sheet. Next, by the same operation as the above operation, a predetermined number of prints are sequentially and continuously performed.

When printing is finished and the image of the next original is printed, before the master 4 is newly wound around the outer peripheral surface of the plate cylinder 100, the used master used previously is wound on the outer peripheral surface of the plate cylinder 100. Peel from. At this time, the plate cylinder 100 is rotated clockwise, the rear end of the master stops at the position of the plate discharge roller 16, and the clamper 2 is opened. Simultaneously with the opening of the clamper 2, the plate discharge rollers 16 and 17 start rotating in the directions of the arrows, respectively, and the plate discharge roller 16 moves from the position shown by the solid line to the position shown by the chain double-dashed line in FIG. After press contacting with the rear end of the master, the plate cylinder 100 rotates in cooperation with each other to start peeling. The used master separated from the outer peripheral surface of the plate cylinder 100 is discarded into the plate discharge box 18. afterwards,
The plate cylinder 100 stops at a fixed position, opens the clamper 2, and enters a plate supply standby state.

Next, after leaving the stencil printing apparatus for a long period of time without using it, the plate cylinder 10 is in a state in which the ink on the plate cylinder 100 has evaporated and decreased or has disappeared.
The opening 1a of the support layer 1, the open area 2a of the mesh screen layer 2, and the base layer 19 are used so that the amount of ink supplied by the ink supply device 200 during one rotation of 0 does not cause ink shortage. An experiment was performed to find the sum of the volumes with the voids 19a. The perimeter L of the image forming area of the plate cylinder 100 is 350 mm, and the width W of the image forming area is 250 mm.
The openings 1a of the support layer 1, the open areas 2a of the mesh screen layer 2 and the base layer 19 respectively.
The area of the void 1a is set to be equal to the circumferential length L and the width W, respectively.

The ink amount (volume cm ³ ) V supplied to the inner peripheral surface of the plate cylinder 100 is V = (ink volume on the surface of the ink roller 6) × (ink roller 6 per one rotation of the plate cylinder 100)
Rotation speed) x (perimeter L of aperture 1a) / (inner perimeter of plate cylinder)
Represented by

The total volume X (c of the openings 1a of the support layer 1 is X (c
m ³ ) is represented by X = open area (W × L) × plate thickness of support layer 1 (t ₁ ) × open area ratio.

Here, the open area ratio is

[0024]

[Equation 1]

Is represented by

The total volume Y (cm ³ ) of the open area 2a of the mesh screen layer 2 is Y = open area region (W × L) × thickness of the mesh screen layer 2 (t ₂ ) ×
It is represented by the open area ratio.

Here, the open area ratio is

[0028]

[Equation 2]

Is represented by

The total volume Z (c of the voids 19a of the base layer 19 is
m ³ ) is represented by Z = void area (W × L) × thickness of base layer 19 (t ₁₉ ) × porosity. Here, the porosity is

[0031]

[Equation 3]

Is represented by

Porosity of support layer ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Layer porosity ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 80% Ink flow value ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥ Φ35mm Press roller hardness ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 30 ° Press roller pressing force ‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ink supply amount in the plate cylinder 1 rotating ink roller per revolution ‥‥‥ 4.8 cm ³ experiments stencil printing device under the above conditions (a trade name. pre It was performed by printing using chromatography preparative VT2500 (Ltd.) manufactured by Ricoh). The results are shown in Table 1.

[0034]

[Table 1]

From the result of the experiment, the opening 1a of the support layer 1 was obtained.
And the open area 2a of the mesh screen layer 2,
If the sum of the volume of the base layer 19 and the space 19a is 84% or less of the amount of ink supplied by the ink roller 6, even if there is no ink in the support layer 1, the mesh screen layer 2 and the base layer 19, With the ink supplied during one rotation of the plate cylinder 100, a good printed image without ink shortage was obtained as compared with the printing of the first sheet, and the start-up of the stencil printing machine was good.

The number of mesh screen layers is not limited to one, and a plurality of layers may be provided.

[0037]

As described above, according to the present invention,
Since the sum of the volume of the openings of the support layer, the open areas of the mesh screen layer, and the voids of the base layer was set to 84% or less of the ink volume supplied by the ink roller, the stencil printing machine was used for a long time. It is possible to provide an inexpensive stencil printing machine in which the rise in reprinting is fast even after being left unattended and there is no loss of paper and ink.

[Brief description of drawings]

FIG. 1 is a sectional view of a stencil printing machine showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing an ink supply device in the stencil printing machine shown in FIG.

3 is an enlarged plan view of an essential part showing a support layer in the stencil printing apparatus shown in FIG.

4 is an enlarged plan view of an essential part showing a mesh screen layer in the stencil printing apparatus shown in FIG.

5 is an enlarged plan view of an essential part showing a base layer of a master in the stencil printing apparatus shown in FIG.

[Explanation of symbols]

 1 Support Layer 1a Open Hole 2 Mesh Screen Layer 2a Open Area 4 Master 5 Rotation Center Shaft 6 Ink Roller 7 Doctor Roller 8 Ink Reservoir 9 Press Roller 13 Printing Paper 19 Base Layer 19a Void 100 Plate Cylinder

Claims (1)

[Claims] 1. A heat-sensitive stencil master comprising a porous flexible base layer and a thermoplastic resin film layer is wound on the outer peripheral surface, and ink is supplied from an inner peripheral surface by an ink supply device. In a stencil printing machine having a plate cylinder that rotates around its rotation center axis, the plate cylinder has a porous cylindrical support layer that forms the inner peripheral surface, and a fibrous shape that forms the outer peripheral surface. And a mesh screen layer formed by crossing the material in a mesh shape, and the sum of the volumes of the openings of the support layer, the open areas of the mesh screen layer, and the voids of the base layer is the ink. A stencil printing machine having 84% or less of the volume of ink supplied to the inner peripheral surface during one rotation of the plate cylinder by the supply device.