JPH03268991A - Ink supply device of stencil printer - Google Patents

Abstract

PURPOSE:To ensure that an ink amount is constantly made uniform regardless of a change in ambient temperature and printing speed with a simple constitution by making all conditions influencing a pressure loss equal in a flow path from the discharge aperture of an ink pump to each discharge hole. CONSTITUTION:An intermediate hose 25 is connected to almost the center of a hollow drum shaft 4 and a multi-stage branch pipe 26 which branches out in each two pieces sequentially and finally ends up with 8 separated discharge apertures 27 at the terminal, is connected to the other end of the intermediate hose 25. The pipe diameter of each part of the branch pipe 26 and the diameter of the discharge aperture 27 are made uniform. One end of the hollow drum shaft 4 is connected to the discharge side of an ink pump and a rubber stopper 28 is provided at a position beyond the connection part of the intermediate hose 25. The ink injected under pressure into the hollow drum shaft 4 using the ink pump is allowed to drip into an ink reservoir 9 from the discharge hole 27 via the multi-stage branch pipe 26. In this case, the diameter and length of pipe and the number of bends from the discharge aperture of the ink pump to each discharge hole 27 are entirely the same relative to the discharge hole.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an ink supply device for a stencil printing device.

In a conventional single-cylinder stencil printing apparatus, generally, as illustrated in FIG. 4, a metal support cylinder 2 with numerous holes and a screen layer 3 made of, for example, mesh polyester fibers attached to the outer circumference of the metal support cylinder 2 are provided. A perforated stencil paper 6 is held in a cylindrical plate cylinder 1 consisting of a plate cylinder 1 by a section 7 with its tip end configured as a clamper provided in the plate hole 1, and then the plate cylinder is The ink is supplied to the numerous holes of the support cylinder 2 from an ink supply device provided inside the support cylinder 2 and oozed out onto the outer periphery of the screen layer 3. Due to the viscosity of the ink, the ink is stuck to the outer circumferential surface of the screen layer 3.

The cylindrical plate cylinder 1 having the stencil paper 6 mounted on its outer circumferential surface in this manner is supplied with ink to its inner circumferential surface by an ink supply device, and then rotated around the shaft 4 by an electric motor to bring the cylindrical plate cylinder 1 into position. The printing paper 11 is sequentially fed between the attached stencil paper 6 and the press roller 10 which is urged toward the outer periphery of the plate cylinder by a spring, and is controlled by a cam (not shown) in synchronization with the rotation of the cylindrical plate cylinder 1. The press roller 10
Printing is performed by conveying the printing paper 11 in pressure contact with the stencil paper 6 and moving ink to the printing paper 11 through the holes in the stencil paper 6.

When printing is performed, ink is consumed in the perforated portions of the stencil paper 6, and the ink is supplied to the screen layer from the holes in the support cylinder, and the ink is supplied to the holes in the support cylinder by an ink supply device.

In the example shown in FIG. 4, the ink supply device contacts the inner peripheral surface of the cylindrical plate cylinder 1 at a position facing the press roller IO,
An ink supply roller 5 that rotates around its own axis in the direction shown by the arrow, a doctor roller 8 that is provided with a slight gap therebetween and rotates around its own axis in the direction shown by the arrow in the figure, and a cylindrical plate. It is formed as a hollow shaft with gear trains 13, 14, 15, 16, 17 that transmit the rotation of the cylinder to these rollers 5, 8 to rotate them, and a plurality of holes in the lower surface.

It is composed of a drum shaft 4 which also serves as an ink supply pipe.

The V-shaped groove formed by the ink supply roller 5 and the doctor roller 8 forms an ink reservoir 9, and ink sucked up and discharged from the ink bag by the ink pump is supplied to the ink reservoir 9. .

The ink in the ink reservoir 9 is taken along with the rotation of the ink supply roller 5 and the doctor roller 8 and is metered as it passes through the gap (doctor gap) 12 between these two rollers. An ink film 22 is formed on the ink film 22 , which is carried by the ink supply roller 5 and supplied to the inner circumferential surface of the cylindrical plate cylinder 1 .

Now, as a means for supplying ink to the ink reservoir 9, there is a conventional method, for example, as shown in FIG. A method is employed in which ink is discharged from an ink pump (not shown) and is press-fitted into the shaft 4 in the direction of the arrow, and dripped into the ink reservoir 9 from the discharge hole 20. In this case, 4
The diameter of each discharge hole is increased in the order of the ink supply direction so that the amount of ink supplied from the hole is approximately the same. The diameter of the hole was determined in advance through experiments. However, the viscosity of ink changes depending on the usage environment5.
For example, when the temperature is low, the viscosity increases and the discharge amount tends to be larger on the upstream side than on the downstream side, and when the temperature is high, the viscosity decreases and the opposite result occurs.

In addition, when the printing speed is changed, in the case of a mechanical ink pump that uses a drive system of a support cylinder, the operating speed also changes, which in turn changes the ink discharge speed.
The uniformity of the discharge amount at each discharge point cannot be maintained. As a result, density unevenness occurs in the printed image, and in some cases, the image becomes blurred, resulting in a disadvantage that the quality of the printed matter deteriorates.

Further, in Japanese Utility Model Publication No. 62-43815, as shown in FIG. Discharge holes 23 are press-fitted into the second pipe 22 extending in the axial direction through the pipe, and are provided at equal intervals on the lower pipe wall of the second pipe 22.
Also disclosed is an ink replenishing device configured to discharge ink into an ink reservoir 9 from openings 24 at both ends. Note that both ends of the second pipe 22 may be closed. With this structure, compared to the above-mentioned example, the discharge amount seems to be symmetrical in the axial direction, but the axial discharge amount distribution is Again, the disadvantage is that uniformity cannot be maintained depending on the environmental temperature and printing speed, making it difficult to obtain high-quality printed matter.

The present invention solves the above-mentioned drawbacks of the conventional ink supply device of a stencil printing apparatus having the above-mentioned structure.The present invention has a simple structure, and the amount of ink discharged from the ink discharge ports arranged in the axial direction is adjusted to the ambient temperature. An object of the present invention is to provide an ink supply device that is always uniform even when printing speed changes.

In order to solve the above-mentioned problems, the present invention aims to improve the flow path from the discharge port of the ink pump of each discharge hole provided in the ink discharge section in the ink supply device of the stencil printing apparatus having the above-described configuration. It is characterized by the fact that all conditions affecting the pressure loss are the same.

As mentioned above, the conditions that affect the pressure loss in the flow path from the ink pump's discharge port to each discharge hole, such as distance, pipe diameter,
Since the discharge hole diameter, number of bends, etc. are all the same, the fluid resistance from the ink pump to each discharge hole is always uniform even if the ink viscosity changes due to temperature changes or the operating speed changes. Become.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are diagrams showing an embodiment in which the present invention is applied to the plate cylinder and ink supply device of the stencil printing apparatus previously explained in FIG. 4. The apparatus is the same as the apparatus shown in FIG. 4 except for the ink supply section to the ink reservoir 9.

Members having the same functions are designated by the same reference numerals and descriptions thereof will be omitted.

In this embodiment, the means for replenishing ink to the ink reservoir 9 is as follows.

An intermediate hose 25 is connected to approximately the center of the hollow drum shaft 4, and the other end of the intermediate hose 25 is a multi-stage hose that branches into two pipes in sequence and finally has eight discharge ports 27 at the ends. The pipe diameter of each part of the 0 branch pipe 26 to which the branch pipe 26 is connected and the diameter of the discharge port 27 are made uniform to about 2 cm. One end of the hollow drum shaft 4 is connected to the discharge side of an ink pump (not shown), and a rubber plug 28 is provided at a position beyond the connecting portion of the intermediate hose 25. Therefore, the ink press-filled into the hollow drum shaft 4 from the ink pump is transferred to the intermediate hose 25. The ink is dripped into the ink reservoir 9 from the discharge hole 27 via the multi-stage branch pipe 26. At this time.

The pipe diameter, length, and number of bends between the ink pump discharge port and each discharge hole 27 are the same for all discharge holes, so that no matter how the ink viscosity and supply speed change, The amount of discharge from each discharge hole becomes uniform.

FIG. 3 is a diagram showing another embodiment of the ink discharge section, in which multi-stage branch grooves 30a are provided on the upper surface of the block 30 in place of the multi-stage branch pipe 26 shown in FIG. Hole 3
0b is provided. An upper lid 31 is fluid-tightly attached to cover the upper surface of the block 3o, and a mounting portion 31a of the intermediate hose 25 is provided at a position to be connected to a portion corresponding to the first branch point of the multi-stage branch pipe. Each part of the groove 30a and the groove 30b have the same diameter, and the length from the intermediate hose attachment part 31a to each hole 30b is the same.

The operation of this device is the same as that of the above embodiment, so it will not be explained again.

As described above, according to the present invention, the amount of ink discharged from the ink discharge holes provided at equal intervals in the axial direction can always be made uniform regardless of changes in environmental temperature or printing speed. Good printed matter without density unevenness can be obtained.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2 is a sectional view thereof, Fig. 3 is a perspective view showing a modified embodiment of the ink discharge section, and Fig. 4 is a perspective view of a general stencil printing device. FIGS. 5 and 6 are a cross-sectional view showing an example of a schematic configuration of a drum section, and a perspective view showing an example of a conventional ink supply device to an ink reservoir, respectively. 1... Cylindrical plate cylinder 2... Support cylinder 3... Screen layer 4... Drum shaft 5... Ink supply roller 6・・・・・・Stencil paper 7・・・・・・Base paper attachment part 8・・・・Doctor roller 9・・・・Ink reservoir 10・・・・Press roller 11・・・・・Printing paper 12...Gap 25...Intermediate hose 26...Multi-stage branch pipe 27...Ink discharge hole 30...Ink discharge section Block 30a...
...Multi-stage branch groove 30b...Through hole 31...Top lid 31a...Intermediate hose connection part

Claims (1)

[Scope of Claims] A cylindrical body formed by overlapping a screen layer on a supporting cylinder that is perforated with countless holes and rotates around its own axis, and that has a base paper attachment part that extends in the axial direction and grips the leading edge of the stencil paper. a plate cylinder; a press roller that presses against the outer circumferential surface of the cylindrical plate cylinder via stencil paper and printing paper and is rotatable around its own axis; an ink supply that supplies ink to the inner circumferential surface of the support cylinder; an ink pump that sucks up ink from an ink pack and replenishes the ink to the ink supply device; an ink pump that is arranged at equal intervals in the axial direction of the support cylinder to drip ink discharged from the ink pump into the ink supply device; The ink supply device has an ink discharge section provided with a plurality of discharge holes, and the ink supply device applies the ink to the stencil paper wound around the plate cylinder, the tip of which is gripped by the base paper mounting portion of the plate cylinder. In an ink supply device of a stencil printing apparatus that performs printing by transferring ink supplied to the peripheral surface to a printing paper conveyed in pressure contact with the base paper through holes in a support cylinder, a screen layer, and holes in a stencil paper, the ink discharge An ink supply device characterized in that the conditions that each discharge hole provided in the section exerts on the pressure loss of the flow path from the discharge port of the ink pump are all equal.