DE3025291A1 - ROTATION PRINT PRESS - Google Patents

Description

Rotogravure press

The invention relates to a rotogravure printing press according to the preamble of claim 1.

One problem with rotogravure presses is the ink on the gravure cylinder to be distributed as evenly as possible in order to obtain the best possible quality print image. For this Purpose is known to use separate ink transfer rollers. However, this leads to an expensive one Construction and increases the manufacturing cost. It is also possible in conjunction with the gravure cylinder to arrange a paint container so that the cylinder is partially submerged therein. In this case it splashes but the color, which results in an uneven print image, especially if the running speed of the paper

15 web is enlarged.

A good print image also requires a fairly high line pressure between the gravure cylinder and the pressure roller. As a result, too much deflection can occur on the gravure cylinder, which affects the print quality is detrimental. To prevent this, separate backup rolls have been used, which complicates the construction.

130062/0412

The invention is based on the object of designing a rotogravure printing press so that it is relatively has a simple structure and still provides a high quality print image even if the speed the paper web is much higher than usual. The rotogravure press to be created should also be able to do this are suitable for coating a paper web e.g. with a copy layer.

The object set is achieved according to the invention with a rotogravure printing press, as it is by the Claim 1 is characterized. Further developments of the invention are described in the subclaims.

According to the invention, a relatively high level is achieved in the basin with the treatment medium of the gravure cylinder

^] C pressure is generated which causes the gravure cylinder to bend prevented. This relatively high pressure also prevents air from entering the basin through the rotating gravure cylinder is pulled. Pollich also no air will remain in the depressions of the gravure cylinder, which the Improved print quality. The invention makes gravure printing possible at speeds of up to 1000 meters per minute run, while usual speeds are around 300 to 500 m per minute.

At high speeds, dust or other undesirable substances can enter the printing nip through the paper web are introduced and from there pass through the pressure cylinder into the basin. The dust is in the treatment medium remain in the form of undissolved particles that can adversely affect the printed image. By the basin with facilities is provided to generate a flow of the treatment medium, these particles are accelerated removed from the basin.

130062/0412

Preferably, a pressure is applied in the basin which satisfies the following condition: 0.5 rv ^ p ^ 0.05 rv, preferably 0.2 rv ^ V- ° i15 rv, where
5p = pressure in the basin,

r = density of the treatment medium used, e.g. the Ink density,

ν = speed of the paper web.

When the speed of the paper web to be printed or otherwise treated or the like is around 1000 m / minute, the pressure in the basin can be up to around 1.4 bar. if a pressure below the lowest limit given by the formula is used, this can be due to the Penetration of air into the depressions of the gravure cylinder could be detrimental to the print quality because the speed of the paper web is greatly reduced.

In order to get an even pressure in the basin, the flow in the basin should be taken into account when determining its shape. If the inflow opening is at one end of the basin, the basin should be one from the inflow side to the opposite Side of decreasing cross-section can be given.

An outlet opening can be provided at the narrower end of the basin so that flow is maintained that stirs the treatment medium well and keeps it as even as possible. To control the flow rate a throttle valve can be assigned to the outlet opening.

The inflow opening for the treatment medium could of course also be in the middle area of the color area.

$ 30062/041 *

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be arranged holder. The container should then have their largest cross-section in the middle and narrow towards the two ends · In this case should both ends may be provided with outlet openings. An equivalent training would be the simultaneous feeding of treatment medium from both ends of the pool, with the arrangement of an outlet opening in the middle area of the Basin. However, harmful turbulence is easily formed in the basin, so that in most cases it is best to feed the treatment medium only at one end of the basin.

To maintain a suitable overpressure in the basin and the amount of pressure on the gravure cylinder To be able to control the transferred treatment medium appropriately, the distance between the basin and the gravure cylinder should be be expediently adjustable. Furthermore, lips made of a soft material with low Coefficient of friction, preferably made of polytetrafluoroethylene, be arranged between the gravure cylinder and the basin, which lips to the gravure cylinder follow parallel long sides of the pelvis. An effective pressure seal is obtained when the lips are close the gravure cylinder are designed to be very narrow, preferably sharp-edged. The basin can be equipped with an in approximately U-shaped cross-section, which is a geometrically favorable shape to the flow turbulence to keep it low. This shape also makes the pelvis stiff and essentially free of bending.

The invention is explained in more detail below with reference to the accompanying drawings. Show it

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1 schematically shows a perspective view of an arrangement according to the invention;

Fig. 2 shows a cross section along the line H-II in Fig. 1. In the drawings, the reference numeral 1 is a Intaglio or rotogravure cylinder designated, above which a pressure roller 2 is arranged. A paper web to be printed 3 or the like is through a Out of the pressure gap which is formed by the gravure cylinder 1 and the pressure roller 2. Below the gravure cylinder 1 an ink container 4 is arranged, in which at its further end 5 printing ink, a coating material or some other treatment medium is introduced. Located at the opposite end of the pool an outlet opening or line 6 with a throttle valve 7? so that a flow through the basin is possible.

In principle, the pressure roller 2 and the ink basin U- do not necessarily have to be in a vertical plane. They should be arranged diametrically opposite one another on both sixths of the gravure cylinder, but their common plane can be inclined, theoretically even lying horizontally. Difficulties could arise, however, due to paint splashing or leaking out of the pool the more this plane is inclined.

Soft lips 8 are arranged between the basin 4 and the gravure cylinder 1. The space between the lips 8 and the gravure cylinder should preferably be about 0.1 to 0.2 mm. In this way, a sufficient seal between the basin and the gravure cylinder is ensured to prevent the treatment medium from splashing out of the paint container into the environment. The exact position of the lips 8 with respect to the basin M and

130062/0412

the gravure cylinder 1 can be adjusted.

A rotogravure press also has a separate doctor blade, but not in the Drawing is shown as it has no relevance to the present invention.

The invention is not limited to the illustrated embodiment limited. Modifications are possible within the scope of the claims.

t30Q62 / 04t2

Claims (1)

Patent claims: 1J rotogravure press with a rotogravure cylinder, a device for supplying printing ink, a coating material or some other treatment medium to the gravure cylinder, and with a pressure roller that works together with the gravure cylinder forms a nip through which a paper web or the like for receiving the treatment medium from the Is guided gravure cylinder, which feed device for the treatment medium with a treatment medium inflow provided elongated rigid basin one of the length of the gravure cylinder substantially has a corresponding length and a much smaller width than the gravure cylinder on which the pressure roller diametrically opposite side of the gravure cylinder, preferably arranged below the gravure cylinder is, and together with the gravure cylinder forms a substantially closed space, characterized in that means are provided to in the basin (4-) to generate a relatively high pressure, the the gravure cylinder (1) in an area opposite the pressure roller (2) essentially above the latter applied over the entire length and thereby prevents the gravure cylinder from bending, and that the basin with Means for generating a flow of the treatment medium is provided. 2. Press according to claim 1, characterized in that the basin (4 ·) has an approximately TJ-shaped Has cross-section. J. Press according to claim 1 or 2, characterized in that devices are provided to maintain the pressure in the basin (4-) according to the following conditions:
0.5 rv = ρ - 0.05 zv ^ »preferably 0.2 rv ² ^ ρ £ 0.15 rv, where
ρ = pressure in the basin,
r = density of the treatment medium, ν = speed of the paper web. 4-, press according to one of claims 1 to 3 »thereby characterized in that an inflow opening for treatment medium at one end (5) of the basin (4-) and an outflow opening (6) is provided at the opposite end of the basin. 5 · Press according to claim 4, characterized in that g e k e η η, that the basin (4 ·) has a decreasing cross-section from the inflow end (5) to the opposite end having. 6. Press according to claim 4- or 5j characterized in that the outflow opening (6) is a Throttle valve (7) is assigned to adjust the pilling rate through the basin (4-). 7. Press according to one of the preceding claims, 530062/0412 characterized in that the distance between the basin (4) and the gravure cylinder (1) is adjustable. 8. Press according to one of the preceding claims, characterized in that the basin towards the gravure cylinder (1) has lips (8) which have the longitudinal edges parallel to the gravure cylinder of the basin and made of a soft material with a low coefficient of friction, preferably made of Polytetrafluoräthy1en exist, and that the lips close the gravure cylinder are very narrow, preferably sharp-edged. 130062 / 0A1 2