DE10049113A1 - Bath device for gravure cylinders - Google Patents

Abstract

A bath device for the galvanic coating of gravure cylinders (21) with a metal combines the advantages of fully immersed and semi-immersed baths. Due to the large immersion depth of the gravure cylinder (21) in an electrolyte (25) with simultaneous enlargement of an anode basket (29), the transfer of a large amount of electricity and a related reduction in the processing time is possible. To install or remove the gravure cylinder (21), it is ensured that the anode basket (29) can be lowered so that it remains completely covered with electrolyte (25), while the gravure cylinder (21) is kept freely above the electrolyte level (31) becomes. The intaglio cylinder (21) can thus be easily installed or removed, while copper wire sections held in the array basket (29) are protected against oxidation.

Description

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

Gravure cylinders, especially for illustration or packaging printing are galvanically coated with a metal as part of a print preparation stage coating, e.g. 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. With subsequent electricity flooding, the anode-side copper dissolves and strikes the Surface of the rotogravure cylinder serving as the cathode, whereby the Desired galvanic coating is created.

Basically, bathroom fixtures with different anode constructions tion 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 fluid and two to the side of the low anode body arranged horizontally on the gravure cylinder be brought up.

Fig. 4 shows an example of such a known fully immersed bath. A gravure cylinder 1 is almost completely immersed in an electrolyte liquid 2 in an upper trough 3 . Below the upper trough 3 , a lower trough 4 is arranged, in which the electrolyte 2 can be drained for installing and removing the gravure cylinder 1 . Laterally from the gravure cylinder 1 , two anode baskets 5 are arranged in which copper wire sections are held 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 is arranged half of the gravure cylinder and vertically up to the cylinder is driven.  

Fig. 5 shows an example of such a full immersion bath with upper hull 3 and the lower vessel 4. Here too, more than half of a gravure cylinder 1 is immersed in electrolyte liquid 2 . In contrast to the fully immersing bath according to FIG. 3, however, anode baskets 6 are provided, which are arranged essentially below half of the gravure cylinder 1 and are pulled up laterally in order to maintain a largely constant distance from the surface of the gravure cylinder 1 to be coated. The anode baskets 6 are connected to anode rails 7 and can be moved vertically together with them. When draining of the electrolyte liquid 2 from the upper hull 3 in the lower vessel 4 so that eventually the overall gravure cylinder 1 no longer ness 2 is immersed, are at least parts of the anode baskets 6 freely in the electrolyte liquid so that the undesired oxidation of the copper is facilitated.

The fully immersed bath is advantageous because of the large immersion depth a lot of current can pass through the gravure cylinder, so that the electroplating sation process runs 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 current quantity can be transferred, resulting in a proportional reduction in Electroplating time leads.

A disadvantage of fully immersing bathrooms is that they can be turned on and off build the gravure cylinder the electrolyte from the upper tub into a more common the lower sump located below must be drained, as the operator ner the gravure cylinder held by the storage device in a crane direction and must not be in contact with the electrolyte long. 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 Newly used gravure cylinder, the electrolyte from the under-tub is like which is 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 called semi-submerged bath used, in which the gravure cylinder independent depending on its size a maximum of about half 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 Accordingly, the cylinder can be installed and removed 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 greater, resulting in a higher quality of the copper deposit the gravure cylinder can be reached. Conversely, there is against The disadvantage of the submerged bath is 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 gravure cylinder would have to be guided around the rotogravure cylinder in order to be the same moderate 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 correspond This would result in appropriate pollution of the electrolyte by copper oxides.

Fig. 6 shows an example of a semi-submerged bath, in which the Tiefdruckzylin of 1 is about half immersed in the electrolyte liquid 2 in the upper tub 3 . 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 gravure cylinder 1 is held by a bearing device, which essentially consists of two bearing bridges 10 , of which only one can be seen in FIG. 6. The bearing brackets 10 are movable on rails 11 by means of spindles 12 in the axial direction of the gravure cylinder 1, so that the two opposed bearing brackets 10 the gravure cylinder 1 can stretch axially, after the intaglio printing cylinder 1 was lifted to the upper hull 3 by means of an unillustrated crane.

As can be seen in FIG. 6, the path for the vertical travel of the anode rails 9 and the anode baskets 8 is limited due to the bearing bridge 10 . An increase in the vertical path could only be achieved by raising crossbeams 13 of the bearing bridges 10 and thus increasing the overall height of the entire bath device, but this was due to the spatial limitations that are usually present with the user, in particular due to the fact that a crane sat above the bath device Gravure cylinder that must be movable is not possible. Accordingly, the anode baskets 8 are arranged largely flat so that they remain completely covered by electrolyte 2 even after draining the electrolyte liquid 2 into the lower trough 4 . An enlargement of the anode baskets 8 in the horizontal plane is possible, but due to the increasing distance to the surface of the gravure cylinder, this does not improve the current.

The invention has for its object a bath device for electroplating specify coating of gravure cylinders with a metal, in which 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 Chen defined.

The bath device according to the invention combines the advantages of the previously known full and semi-submerged 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 Electroplating phase at least a third of the lateral surface of the gravure printing opposite cylinder with a small distance, therefore on the lateral surface of the rotogravure cylinder is pulled up sideways and thus a vertical extension kung, it remains in the cylinder change phase, i.e. on or off Construction of the gravure 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.

It is particularly advantageous in this context if the Lagereinrich device has two bearing brackets that extend outside the upper trough exclusively on a wall that extends essentially parallel to an axial direction of the Tiefdruckzylin, ie z. B. are supported on a front wall of the upper trough, but not on an opposite wall with respect to the upper trough, e.g. B. the rear wall of the upper hull. Due to the one-sided support of the bearing bridges in contrast to the z. B. in connection with Fig. 5 ten-sided support, it is possible that half of the upper trough is not covered by the cross member of the associated bearing brackets. There, an anode rail which is electrically conductively coupled to the metal holding device can be arranged, which is thereby freely movable vertically without striking against the cross members of the bearing bridges. The limitation of vertical mobility described in connection with the prior art shown in FIG. 6 thus no longer exists according to the invention. Since the metal holding device can be moved almost arbitrarily vertically, 1 without the overall height of the bathroom device being increased.

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 outside fits wall of the upper hull essentially required the space required Anode baskets and rotogravure cylinders, so that despite the larger upper tub Fe does not increase or increases the upper trough volume only slightly occurs.

These and other advantages and features of the invention are set out below explained with the help of the accompanying figures. Show it:

Figure 1 shows a bath device according to the invention in a schematic Dar position during a cylinder change phase.

Phase Figure 2 illustrates the Badvorrichtung of Figure 1 during a plating..;

Fig. 3, a metal holding device in schematic side view;

Fig. 4 is an example of a prior art full immersion bath;

Fig. 5 shows a further example of a known full immersion bath; and

Fig. 6 shows an example of a semi-submerged bath with a bearing bracket.

Figs. 1 and 2 show a Badvorrichtung according to the invention in differing chen process states, namely on the one change at the time of a cylinder (Fig. 1) when a gravure cylinder 21 just not using a represents crane provided inserted into the Badvorrichtung and associated by a bearing means Bearing bridges 22 is held and in a galvanizing phase ( Fig. 2). Since the components in FIGS. 1 and 2 are essentially identical, they are identified by the same reference numerals.

The bath device has an upper trough 23 and a lower trough 24 arranged underneath. In the upper hull 23 and in the lower hull 24 is a liquid electrolyte 25, which is pumped by a pump 26 from the lower tray 24 in the upper hull 23 and then flows back into the lower hull 24 via a vertically movable in at least two positions overflow 27th Alternatively, it is also possible to arrange two mutually open overflows at different levels.

In the upper trough 23 there is also a vertically movable anode device which essentially consists of an anode rail 28 and an anode basket 29 which is electrically and mechanically coupled to the anode rail 28 and serves as a metal holding device. The anode basket 29 can also consist of several assembled anode baskets or grids. Usually the anode basket 29 is made of titanium and cut with Kupferdrahtab or copper granulate as metal elements 29 a filled. When current is applied, the copper decomposes, so that copper ions migrate via the electrolyte 25 to the surface of the gravure cylinder 21 connected as a cathode and settle there in the form of a copper coating. A detailed description of the anode basket 29 will be given later with reference to FIG. 3.

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

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

As can be seen in FIGS. 1 and 2, about one half of the upper trough 23 remains freely accessible at the top through the bearing bridges 22 , so that the anode rail 28 which is parallel to the axial direction of the gravure cylinder 21 is free to move vertically. The vertical movement of the anode rail 28 with the anode basket 29 is otherwise known, so that a further description and illustration is not necessary.

The degree of filling of the electrolyte 25 in the upper trough 23 , ie the height level of the electrolyte 25 , can be adjusted with the aid of the vertically movable overflow 27 between a height level 31 in the cylinder change phase and a height level 32 in the galvanizing phase.

Fig. 2 shows the bath device in the galvanization phase, in which the gravure cylinder 21 is almost completely immersed. In particular, immersion depths of larger cylinders (1500 mm in circumference) of more than 65% and in smaller cylinders (800 mm in circumference) up to approximately 80% can be achieved.

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

After the electroplating phase has ended, the anode rail 28 is moved with the anode basket 29 down into the upper trough 23 , as shown in FIG. 1. Simultaneously or with a time delay, the overflow 27 is lowered, so that the electrolyte 25 flows down to the level 31 into the lower trough 24 .

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

To reduce the amount of electrolyte in the upper trough 23, the upper hull 23 is tapered at the bottom. The taper can e.g. B. with the help of additionally inserted sheets 33 or by appropriate adaptation of the walls of the upper trough. It is also possible to use blocks or boxes to displace volumes. Limiting or reducing the volume of the upper trough 23 has the advantage that the lower trough 24 does not have to be pumped upwards with an excessive amount of electrolyte 25 . Accordingly, there is no risk that the bottom pan 24 will be completely emptied and the pump 26 will run dry.

FIG. 3 shows the anode basket 29 , the anode rail 28 and an anode bracket 34 connected to the anode rail 28 in relation to the gravure cylinder of FIG. 21 .

The anode bracket 34 is connected to the anode rail 28 and represents a holder for the anode basket 29 .

The anode basket 29 consists of a titanium mesh material and receives the metal elements 29 a as copper wire sections or copper granules. The od basket 29 is supported on the anode bracket 34 . Its underside is formed entirely by the mesh material, with walls 35 being drawn up in certain sections, which prevent the otherwise loosely lying metal elements 29 a from slipping, ie the copper granules.

Two steep sections 36 of the anode basket 29 additionally have on their top side covers 37 , which are intended to prevent the loose metal elements 29 a from falling out of the basket. The covers 37 are permeable so that the copper ions can pass through them. The covers 37 and the partition walls 35 are made of titanium material, otherwise, in particular in particular in the flat sections, the top of the anode basket 29 is freely accessible.

The design of the anode basket 29 enables the anode basket 29 to largely adapt to the shape of the intaglio cylinder 21 and its sides are drawn up in a steeply rising manner. The lateral rise is greater than an angle of repose of the metal elements 29 a to be held on the anode basket 29 . Falling out of the metal elements 29 a - 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, a flat anode basket 8 is realized, on which the metal elements merely rest, without additional holding measures being provided. The lateral rise angle of the anode basket 8 is thus limited by the angle of repose. With a greater increase in the anode basket 8 , the metal elements would not remain in their original position, but would collect in the middle, at the lowest possible point.

Claims (9)

1. 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 in the upper tub ( 23 ) at least vertically movable anode device ( 28 , 29 ) with a metal in the form of metal elements ( 29 a) hold the metal holding device ( 29 ); and with
one holding the gravure cylinder ( 21 ) horizontally in the upper trough ( 23 ) horizontally the bearing device ( 22 ) into or out of 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 ) during an electroplating phase and during the cylinder change phase can be set to two different height levels ( 31 , 32 );
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 height level ( 31 ) of the electrolyte ( 25 ) in the cylinder change phase lies 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. 2. Bath device according to claim 1, characterized in that the Me tallhalteeinrichtung ( 29 ) ge during the galvanization phase at least half of the lateral surface of the gravure cylinder ( 21 ) ge compared with a small distance. 3. 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 ). 4. Bath device according to one of claims 1 to 3, characterized in that the metal holding device has a substantially corresponding to the lateral surface of the gravure cylinder ( 21 ) curved, laterally rising anode basket ( 29 ), wherein the lateral rise is greater than an angle of repose on the anode basket ( 29 ) to be held metal elements ( 29 a). 5. 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. 6. Bath device according to one of claims 1 to 5, characterized in that the upper trough ( 23 ) is tapered in its lower region. 7. Bath device according to one of claims 1 to 6, characterized in that the bearing device has at least one bearing bridge ( 22 ) outside the upper trough ( 23 ) exclusively on a wall extending essentially parallel to an axial direction of the gravure cylinder ( 21 ) is supported, but not on a wall opposite the upper trough ( 23 ). 8. Bath device according to claim 7, characterized in that the bearing device has two bearing bridges ( 22 ) which are movable in the axial direction of the gravure cylinder ( 21 ) relative to each other. 9. 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 ) is arranged.