EP1195453A2 - Bath device for engraver cylinder - Google Patents

Abstract

Bath comprises: (i) an upper sink (23) filled with an electrolyte (25); (ii) an anode arrangement (28, 29) vertically moving in the upper sink with a metal holder holding the metal in the form of metal elements; and (iii) a bearing device (22) for horizontally holding low pressure cylinders. The metal holder is completely covered by the electrolyte in the cylinder changing phase. Preferred Features: The metal holder stands opposite at least one half of the casing surface of the cylinder during galvanizing. The metal holder surrounds the lower half of the cylinder.

Description

The invention relates to a bath device according to the preamble of claim 1 for the galvanic coating of gravure cylinders with one Metal.

Gravure cylinders, especially for illustration or packaging printing are galvanically coated with a metal coating as part of a print preparation stage, z. B. made of copper, into which the engraving is then introduced can be, which corresponds to the later printed image. For the galvanic Appropriate baths are known for coating, which are sometimes very large and heavy gravure cylinders (up to 2,500 kg, 3,700 mm bale length, 1,530 mm circumference) can be used in a liquid electrolyte. In the Electrolyte will continue to be an anode, e.g. B. a copper wire sections or Titanium basket containing copper granules, used. Subsequent current flow the anode-side copper dissolves and strikes on the Surface of the rotogravure cylinder serving as the cathode, whereby the Desired galvanic coating is created.

Basically, bathroom fixtures with different anode constructions and various immersion depths for the rotogravure cylinders. So there is a so-called fully immersed bath, in which the gravure cylinder up to 90% immersed in the electrolyte liquid and two on the side of the gravure cylinder arranged anode body horizontally on the gravure cylinder be brought up.

Fig. 4 shows an example of such a known fully immersed bath. On Gravure cylinder 1 is almost completely in an electrolyte liquid 2 in one Upper tub 3 immersed. Below the upper trough 3 is a lower trough 4 arranged in which the electrolyte liquid for installing and removing the gravure cylinder 1 2 can be drained. Laterally from the gravure cylinder 1 two anode baskets 5 are arranged in which copper wire sections are held are and which can be moved horizontally to the gravure cylinder 1.

Furthermore, a fully immersed bath is known in which an anode basket is underneath the gravure cylinder is arranged and moved vertically to the cylinder becomes.

5 shows an example of such a fully immersed bath with upper tub 3 and under-tub 4. Again, an intaglio cylinder 1 is more than half immersed in electrolyte liquid 2. In contrast to the fully immersed bathroom 3, however, anode baskets 6 are provided, which are essentially below of the gravure cylinder 1 are arranged and pulled up to the side a largely constant distance from the surface to be coated Gravure cylinder 1 must be observed. The anode baskets 6 are with anode rails 7 connected and vertically movable together with them. When draining the Electrolyte liquid 2 from the upper trough 3 into the lower trough 4 such that finally the entire rotogravure cylinder 1 no longer in the electrolyte liquid 2 immersed, at least parts of the anode baskets 6 are exposed, so that the unwanted oxidation of the copper is made possible.

The fully immersed bath is advantageous because of the large immersion depth much current can be passed through the gravure cylinder, so the plating process expires quickly. The specific cathodic current load, i.e. H. the amount of electricity based on the area of the electrolyte immersed in the electrolyte Pressure cylinder, is not larger than in comparison to baths in which the gravure cylinder is not full, but z. B. is only half immersed. It it is obvious that the greater the immersion depth, the greater the amount of electricity can be transmitted, resulting in a proportional reduction in the Electroplating time leads.

A disadvantage of fully immersing bathrooms is that they can be installed and removed the gravure cylinder, the electrolyte from the upper trough into a usually lower sump located below must be drained because the operator the gravure cylinder held by the storage device in a crane device must transfer and do not come into contact with the electrolyte may. By draining the electrolyte from the top pan but also the anodes and especially those in the anode baskets Copper wire sections or copper granules exposed, which leads to oxidation of copper leads. At the beginning of the next electroplating process with a When the gravure cylinder is newly inserted, the electrolyte from the lower trough is restored pumped into the upper tub and accordingly flows through the Anode baskets. The copper oxide layers are due to the flow effect detached the copper wire sections and get into the as dirt particles Electrolyte. When the power is switched on, these dirt particles build up the surface of the gravure cylinder to be coated and form nuclei, which can lead to a "spotty" copper precipitation.

A so-called is therefore usually used for the galvanization of gravure cylinders semi-submerged bath used in which the gravure cylinder independently maximum of about half of its size in the electrolyte liquid is immersed. The anode basket containing the copper wire sections becomes delivered vertically from below. Here are the dimensions of the upper hull chosen so that the anode baskets in the upper trough moved down as far that the copper wire sections are still fully covered with electrolyte even if the gravure cylinder is in due to the discharge of electrolyte the lower trough is no longer immersed in the electrolyte. The gravure cylinder can be installed and removed accordingly without the Copper anodes are exposed and can oxidize.

The semi-submerged bath therefore has the same as the fully submerged bath Advantage that the cleanliness in the upper tub due to much less copper oxidation is larger, resulting in a higher quality of the copper deposit the gravure cylinder can be reached. Conversely, there is opposite the immersing bathroom the disadvantage that due to the lower Immersion depth the electroplating speed is slower.

However, an increase in the diving depth alone could not improve this bring because the amount of electricity used for galvanizing by the size of the Anode surface is set. However, enlarging the anode would have led to As a result, the essentially flat with little vertical extension Anode basket arranged below the intaglio cylinder in the shape of a half cylinder would have to be routed around the gravure cylinder in order to Distance between the anode and the surface to be coated Gravure cylinder and thus to obtain a uniform current density. This semi-cylindrical shape of the anode basket has the consequence that the Anode basket extends far up in the vertical direction and thus when draining of the electrolyte for changing the copper wire sections in the Anode baskets are no longer completely covered by electrolyte. A corresponding The result would be contamination of the electrolyte by copper oxides.

Fig. 6 shows an example of a semi-submerged bath in which the gravure cylinder 1 about half immersed in the electrolyte liquid 2 in the upper tub 3 is. Anode baskets 8 are arranged below the gravure cylinder 1, which can be moved vertically to a small extent together with anode rails 9.

The rotogravure cylinder 1 is held by a storage device which in the Essentially consists of two bearing bridges 10, of which only one in FIG. 6 is recognizable. The bearing bridges 10 are on rails 11 with the aid of spindles 12 movable in the axial direction of the gravure cylinder 1, so that the two opposite bearing bridges 10 axially tension the gravure cylinder 1 can after the gravure cylinder 1 by means of a not shown Crane was lifted into the upper trough 3.

As can be seen in Fig. 6, is the way for the due to the bearing bracket 10 vertical travel of the anode rails 9 and the anode baskets 8 limited. An increase in the vertical path could only be increased by Cross members 13 of the bearing brackets 10 and thus an increase in height of the entire bath device, which is due to the usual spatial limitations existing at the user, in particular due to the fact that a crane and gravure cylinder are located above the bath device must be movable, is not possible. Accordingly, the anode baskets 8 arranged largely flat so that even after draining the electrolyte liquid 2 remain completely covered by electrolyte 2 in the lower trough 4. An enlargement of the anode baskets 8 in the horizontal plane is possible, but due to the growing distance to the surface of the gravure cylinder no improvement in terms of greater amperage.

The invention has for its object a bath device for galvanic Coating of gravure cylinders with a metal to specify on the one hand a reduction in the galvanization time as with fully immersed ones Bathrooms, on the other hand a higher quality due to greater cleanliness of the semi-submerged baths can be reached.

The achievement of the object is specified in claim 1. Advantageous further developments of the invention are in the dependent claims Are defined.

The bath device according to the invention combines the advantages of the previously known full diving and semi-diving baths. This is how the gravure cylinder becomes more than half immersed in the electrolyte, so that larger currents and a reduction in processing times is possible. Although the im Metal holding device essentially forming the anode baskets during the Galvanization phase at least a third of the lateral surface of the gravure cylinder faces at a short distance, thus on the outer surface of the rotogravure cylinder is pulled up sideways and thus a vertical extension it remains in the cylinder change phase, i.e. when installing or removing of the rotogravure cylinder completely covered with electrolyte, as has been the case up to now was only the case with semi-submerged baths.

For this it is necessary that the upper trough deepens compared to the state of the art is so that the material holding device, i.e. H. the anode baskets, far enough lower so that they are completely off even when the cylinder is converted Electrolyte remain flushed.

In this context, it is particularly advantageous if the bearing device has two bearing bridges, the only outside of the upper hull on a substantially parallel to an axial direction of the gravure cylinder extending wall, e.g. B. supported on a front wall of the upper trough are, but not on an opposite with respect to the upper trough Wall, e.g. B. the rear wall of the upper hull. Through the one-sided support of the Bearing bridges in contrast to the z. B. explained in connection with FIG. 5 double-sided support, it is possible that half of the upper hull is not covered by the cross members of the associated bearing brackets. There can an anode rail electrically conductively coupled to the metal holding device are arranged, which is thereby freely movable vertically, without against attach the crossbeams of the bearing bridges. The particularly related with the limitation described in Figure 6 prior art vertical mobility no longer exists according to the invention. Thereby the metal holding device can be moved almost arbitrarily vertically, without increasing the height of the bathroom device.

Another advantageous embodiment is that the upper trough in its lower area is tapered. This makes it possible to change the volume of the To reduce the upper trough or the amount of electrolyte in the upper trough or to be kept constant even though the depth of the upper hull is increased. Because it is If the volume of the upper trough is too large, there is a risk that so much electrolyte from the lower tub arranged below the upper tub until it is reached an overflow in the upper tub is pumped into the upper tub that the Pump runs dry. The volume of the lower hull is not arbitrary enlargeable, since an increase in their height corresponds to the total height of the Bath fixture would impact, which is not for the reasons mentioned above is desirable while increasing the width of the underpan Transportability of the bath device, especially when transporting trucks severely restricted. It should be noted that the bathroom fixtures of the State of the art the limit values with regard to length and width for one Have already fully exhausted transport with reasonable effort. A further enlargement of the bath device and in particular the length and The width of the lower trough is therefore not desirable.

By tapering the upper trough in the lower area, the outer wall adapts the upper hull essentially the required space of Anode baskets and rotogravure cylinders, so that despite the greater upper trough depth there is no or only a slight increase in the upper trough volume.

Fig. 1

eine erfindungsgemäße Badvorrichtung in schematischer Darstellung während einer Zylinderwechselphase;

Fig. 2

die Badvorrichtung gemäß Fig. 1 während einer Galvanisierungsphase;

Fig. 3

eine Metallhalteeinrichtung in schematischer Seitenansicht;

Fig. 4

ein Beispiel für ein bekanntes volltauchendes Bad;

Fig. 5

ein weiteres Beispiel für ein bekanntes volltauchendes Bad; und

Fig. 6

ein Beispiel für ein halbtauchendes Bad mit Lagerbrücke.

These and other advantages and features of the invention are explained in more detail below with the aid of the accompanying figures. Show it:

Fig. 1

a bath device according to the invention in a schematic representation during a cylinder change phase;

Fig. 2

1 during a galvanizing phase;

Fig. 3

a metal holding device in a schematic side view;

Fig. 4

an example of a well-known full immersion bath;

Fig. 5

another example of a well known full immersion bath; and

Fig. 6

an example of a semi-submerged bath with a bearing bridge.

1 and 2 show a bath device according to the invention in different Process states, namely on the one hand at the time of a cylinder change (Fig. 1) when an intaglio cylinder 21 just by means of a not shown Crane inserted into the bath device and through to a storage facility associated bearing brackets 22 is held and in a galvanization phase (Fig. 2). Since the components in FIGS. 1 and 2 essentially are identical, they are identified by the same reference numerals.

The bath device has an upper trough 23 and a lower one Under pan 24 on. Located in the upper tub 23 and in the lower tub 24 there is a liquid electrolyte 25 which is pumped out of the lower tub 24 is pumped into the upper tub 23 and at least one vertically two positions movable overflow 27 back into the lower pan 24th flows. Alternatively, it is also possible to open two mutually open overflows to arrange different heights.

In the upper tub 23 there is also a vertically movable anode device arranged, which consists essentially of an anode rail 28 and one with the Anode rail 28 electrically and mechanically coupled and as a metal holding device serving anode basket 29 there. The anode basket 29 can also consist of several composite anode baskets or grids. Usually the anode basket 29 is made of titanium and with copper wire sections or copper granules filled as metal elements 29a. When current is applied the copper decomposes so that copper ions pass through the electrolyte 25 migrate to the surface of the gravure cylinder 21 connected as cathode and settle there in the form of a copper coating. An exact description of the anode basket 29 takes place later with reference to FIG. 3.

Only one of the bearing bridges 22 is shown in FIGS. 1 and 2. The two Bearing bridges 22 are on rails 30a, 30b in the axial direction of the gravure cylinder 21 by means of spindles or other suitable adjustment mechanisms movable so that they clamp the gravure cylinder 21 between them and keep it rotatable.

In contrast to the prior art, the bearing bridges 22 are only one-sided, namely supported on the front of the upper trough 23. Accordingly two sets of rails 30a, 30b are required to absorb the moment.

As can be seen in FIGS. 1 and 2, the one-sided bearing remains Bearing bridges 22 about half of the upper trough 23 freely accessible at the top, see above that there extending parallel to the axial direction of the gravure cylinder 21 Anode rail 28 is freely vertically movable. The vertical movement of the Anode rail 28 with the anode basket 29 is also known, so that a further description and presentation is not required.

The degree of filling of the electrolyte 25 in the upper tub 23, i. that is, the height level of the electrolyte 25, can be adjusted using the vertically movable overflow 27 adjust between a height level 31 in the cylinder change phase and a level 32 in the electroplating phase.

Fig. 2 shows the bath device in the electroplating phase, in which the gravure cylinder 21 is almost completely submerged. In particular, Immersion depths of large cylinders (circumference 1500 mm) of more than 65% and at reach smaller cylinders (circumference 800 mm) up to about 80%.

The anode basket 29 is pulled up laterally, so that it is compared to the known one semi-submerged bath forms an approximately 50% larger basket surface.

After completion of the galvanizing phase, the anode bar 28 is connected to the Move the anode basket 29 down into the upper trough 23, as shown in FIG. 1. At the same time or with a time delay, the overflow 27 is lowered so that the electrolyte 25 flows down to the level 31 in the lower trough 24.

As can be seen in FIG. 1, a state can be achieved in which the anode basket 29 is still completely covered by the electrolyte 25 is, while the gravure cylinder 21 is completely free above the electrolyte level 31 stands and can be easily lifted there with the crane, not shown can.

To reduce the amount of electrolyte in the upper tub 23 is the upper tub 23 tapers in the lower area. The taper can e.g. B. with additional help used sheets 33 or by appropriate adjustment of the walls of the Upper tub done. It is also possible to use blocks or boxes to displace volume. Limiting or reducing the volume the upper trough 23 has the advantage that the lower trough 24 does not become excessive much electrolyte 25 has to be pumped up. Accordingly there is no risk that the lower trough 24 is completely emptied and the Pump 26 runs dry.

Fig. 3 shows the anode basket 29, the anode rail 28 and one with the anode rail 28 connected anode brackets 34 in relation to the gravure cylinder 21st

The anode bracket 34 is connected to the anode bar 28 and provides one Bracket for the anode basket 29.

The anode basket 29 consists of a titanium mesh material and takes the Metal elements 29a as copper wire sections or copper granules. The anode basket 29 rests on the anode bracket 34. Its underside becomes complete formed by the mesh material, with partitions in certain sections 35 are pulled up, the excessively slipping of the otherwise loose overlying metal elements 29a, d. H. prevent the copper granulate.

Two steep sections 36 of the anode basket 29 additionally have on their top Covers 37 to prevent the loose metal elements 29a can fall out of the basket. The covers 37 are permeable, so that the copper ions can pass through it. Even the covers 37 and the partition walls 35 are made of titanium material. Otherwise, especially in the flat sections, the top of the anode basket 29 is free accessible.

The design of the anode basket 29 enables the anode basket 29 largely adapt to the shape of the gravure cylinder 21 and its sides have risen sharply. The side climb is stronger than one Angle of repose of the metal elements 29a to be held on the anode basket 29. On Falling out of the metal elements 29a - in particular from the steep sections 36 can only be prevented by the covers 37.

In comparison, in the prior art according to FIG. 6 there is a flat anode basket 8 realized, on which the metal elements only rest, without additional Holding measures are provided. The lateral rise angle of the Anode basket 8 is thus limited by the angle of repose. With a stronger one Rise of the anode basket 8, the metal elements would not be in their original Stand still, but in the middle, at the lowest possible point collect.

Claims (9)

Bath device for the galvanic coating of gravure cylinders (21) with a metal, with an upper trough (23) which can be filled with an electrolyte (25); an anode device (28, 29) at least vertically movable in the upper trough (23) with a metal holding device (29) holding the metal in the form of metal elements (29a); and with a bearing device (22) horizontally holding the gravure cylinder (21) in the upper trough (23), into or from which the gravure cylinder (21) can be installed or removed during a cylinder change phase; in which the degree of filling of the electrolyte (25) in the upper trough (23) can be adjusted to two different height levels (31, 32) during a galvanization phase and during the cylinder change phase; at least half, preferably at least 65%, of the gravure cylinder (21) can be immersed in the electrolyte (25) during the galvanizing phase; the metal holding device (29) faces at least a third of the lateral surface of the intaglio cylinder (21) at a short distance during the galvanizing phase; and where the level (31) of the electrolyte (25) in the cylinder change phase is below the gravure cylinder (21), so that the gravure cylinder (21) does not dip into the electrolyte (25); characterized in that the metal holding device (29) is completely covered by electrolyte (25) in the cylinder change phase. Bath device according to claim 1, characterized in that the metal holding device (29) is at least a short distance apart from at least half of the lateral surface of the gravure cylinder (21) during the galvanizing phase. Bath device according to claim 1 or 2, characterized in that the metal holding device (29) surrounds the lower half of the gravure cylinder (21) held horizontally by the bearing device (22). Bath device according to one of Claims 1 to 3, characterized in that the metal holding device has an anode basket (29) which rises laterally and rises substantially in accordance with the lateral surface of the gravure cylinder (21), the lateral rise being greater than an angle of repose which is on the anode basket ( 29) metal elements (29a) to be held. Bath device according to one of claims 1 to 4, characterized in that a lower trough (24) is arranged below the upper trough (23) for receiving electrolyte (25) from the upper trough (23), in particular in the cylinder change phase. Bath device according to one of claims 1 to 5, characterized in that the upper trough (23) is tapered in its lower region. Bath device according to one of claims 1 to 6, characterized in that the bearing device has at least one bearing bridge (22) which is supported outside the upper trough (23) exclusively on a wall which extends essentially parallel to an axial direction of the gravure cylinder (21), but not on a wall opposite the upper trough (23). Bath device according to claim 7, characterized in that the bearing device has two bearing bridges (22) which are movable relative to one another in the axial direction of the gravure cylinder (21). Bath device according to claim 7 or 8, characterized in that the anode device has an anode rail (28) which is electrically conductively coupled to the metal holding device (29) and can be moved vertically and with respect to the gravure cylinder (21) opposite the support of the bearing bridge (22) or the bearing bridges (22) are arranged.

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