EP1115912B1 - Device for partial electrochemical treatment of bar-shaped objects - Google Patents

Abstract

In a device, rod-shaped objects 10 (rods of various length and diameter) are electrochemically partially processed in dip plants (galvanized, pickled). Stationary tubular electrodes 30, into which the rods 10 are centrically entered, are provided in the plating tank of the plant. The surfaces to be plated are each axially limited by an adjustable membrane carrier 26, in which elastic shielding membranes 9 for delimiting the field lines are arranged. The membranes 9 are held by membrane holders 5. The membrane holders 5 are arranged in a cage where they are free to move radially and are provided with inner centering springs 7 and with outer centering springs 19 so that the membrane holder 5 and the membranes 9 are held in such a way as to be self-centering.

Description

The invention relates to a device and a method for partial Treat, namely electroplating, electrochemical etching or electrochemical Cleaning of rod-shaped items to be treated in immersion baths, namely electroplating, etching and cleaning systems.

In the following description, the material to be treated is referred to as a rod. Devices for electrochemical etching, electroplating and electrochemical cleaning of elongated cylinders, in particular of round bars are known. These rods can be on one or both Ends are tapered and / or threaded. An example of this are Cylinder for vehicle shock absorbers. However, the invention is not restricted on the treatment of round bars. It is also suitable for treatment of bars with a different cross section.

The electrochemical treatment of the rods is used, for example, in shock absorber cylinders to improve wear and corrosion properties.

For this purpose, the rods are only used on those that are stressed during operation Surfaces electrolytically coated with hard chrome. The other places of the Bars should remain uncoated or partially with a thin flash chrome layer can be provided as temporary surface protection. For improvement The surface of the chrome layer becomes electrochemical before it can be bonded etched. Insolubles are preferred for both process steps Electrodes used. Between the individual treatment steps the rods rinsed in electroplating systems. A transport device ensures the transport of the bars from treatment station to treatment station.

For the partial treatment of the bars in the middle of the bar, the ends must be masked, i.e. be shielded in such a way that they are dimensionally precisely predetermined Areas of no metal or flash chrome as temporary protection is deposited. The boundaries between the deposition area and the Areas not to be coated are generally closely tolerated. With certain For shock absorber cylinders, for example, the uncoated area pass into the coated area within only ± 1 millimeter. The the layer to be deposited must be uniformly thick up to this limit. Edge effects, i.e. a layer thickness increase or decrease at the area limits, must be avoided. The aim of the precise coating is a to avoid subsequent smoothing.

In the known systems, the rods are attached to frames and treated, the racks in turn attached to transportable goods carriers are. The frames are provided with individual masks so that both rod ends not be coated in the intended area. For all occurring Bar lengths, bar diameters and coating areas must be specified A sufficient number of masks and frames are available in an electroplating system his. Because the frames also supply the bath current to the bars serve, you must be metallic conductive. The metal has to go through plastic coatings protected from galvanizing.

In the document DE-AS 11 03 103 there is a device for galvanic Chrome plating of the outer surface of poppet valve stems is described. To the To be able to partially galvanize shafts, they are in tubular anodes centrally arranged and on the top in a stepped metal core attached. The current is fed through the metal core, the metal core is separated from the electrolytic cell by an insulating body. The Metal core and the insulating body limit the electroplating layer at the top End of the shaft. The bottom end is covered with a protective varnish from unwanted Galvanization protected.

This embodiment has the disadvantage that each individual is to be galvanized Body individually attached and the protective varnish on one end of the body must be applied accurately. Also the peeling off of the protective lacquer after electroplating is expensive.

DE 197 22 983 A1 describes methods and a device with which a partial electrochemical treatment, especially electrochemical Treatment of bars with different dimensions, in Immersion baths is made possible.

There are defined adjustable masks with sealants in the form of End cuffs on both rod ends to limit the ones to be treated Areas used. In a loading station, several take electrically conductive grippers fastened to the goods carrier at the same time on each side a staff. When entering the electrolytic treatment station each rod into a single cell, consisting of the rod and one stationary tubular electrode is formed. The upper and lower electrolytic effective electrode end is made of a tubular axially adjustable Mask determined. The mask ends are each closed with a cuff. When the product carrier is lowered, the rod first moves through the upper one Cuff, then into the electrode and then through the lower cuff therethrough. By independently adjusting the top and bottom Masks parallel to the rod axis are the two coating limits or the surface to be coated on the rod is uniform for each product carrier or each row of bars set on the goods carrier. With this procedure, though the disadvantages of the known rack technology avoided, with one each special mask for each rod dimension in the form of caps or holders must be worked. In practice, however, it often happens that Material to be treated is suspended at an angle, since metal deposits adhere to the Pliers holders have formed or the holders are damaged. When entering gap in the masks of the material no longer hanging centrically the cuffs on the side and can be damaged by sharp edges become. A precisely dimensioned electroplating with damaged sleeves is therefore no longer possible. To make matters worse, damage the cuffs only after the plating material has been extended of the system because the cuffs are immersed in the electrolyte are not visible from the surface of the bathroom. That under Treatment items produced under these circumstances are unusable.

The invention is therefore based on the problem, the disadvantages of the known Method and devices for shielding during electroplating Avoid bars and especially the work required to shield the areas not to be electroplated on bars if possible to keep small. In addition, the process should also under production conditions work flawlessly.

The problem is solved by a self-centering device according to claim 1 and the method according to claim 11 solved. Preferred embodiments are specified in the subclaims.

a. mindestens einen Badbehälter,

b. in dem mindestens einen Badbehälter rohrförmige Elektroden und mindestens einen rohrförmigen Membranträger, in den das Behandlungsgut zumindest teilweise einfahrbar ist, und

c. innerhalb des mindestens einen Membranträgers angeordnete Membranhalter.

The device according to the invention is used for the partial electrochemical treatment of rod-shaped items to be treated in immersion bath systems. The device comprises

a. at least one bath container,

b. in the at least one bath container tubular electrodes and at least one tubular membrane carrier into which the material to be treated can be at least partially retracted, and

c. membrane holder arranged within the at least one membrane carrier.

The tubular membrane supports are preferably made of chemical resistant and at least electrically non-conductive on the surface Material.

The device points axially in accordance with the dimensions of the material to be treated adjustable, electrically non-conductive shielding devices. For every rod at least one shielding device is provided. For example, a Shielding device at the lower end of the rod inside the bath Avoiding the electrochemical treatment of this part of the Staff provided. In this case, the upper part of the Bar remain untreated in that this section is not in the Immersed treatment liquid. Shielding devices can also be used be provided at both ends of the rod.

The shielding devices each comprise at least one cage within the tubular membrane support. The cages are arranged so that the Treated goods can be pushed through them, and will be by at least one cage lid and at least one cage bottom educated. In each cage is a membrane holder holding a membrane between the cage lid and the bottom of the cage are mounted so that they can move radially. At least an inner centering spring for guiding the material to be treated and at least one outer centering spring for centering the membrane holder and the membrane in the cage are provided on each membrane holder. The Membranes are preferably made of chemically stable, stretchable and electrically non-conductive material.

The cages are on the side of the shielding device facing the center of the rod arranged. The outer centering springs are preferably rod-shaped formed as leaf springs and on the outer surfaces of the membrane holder fixed tangentially. They serve to center the membrane holder and the Membrane in the cage and have a radial pressure of one not centric held rod against the membrane and the membrane holder. The Spring force of the outer centering springs is due to the strength of the elastic Adapted membranes. It should be chosen so large that the membranes by a lateral pressure of the material to be treated do not gap or in Extreme case tear and the shielding effect is lost at this point.

The spring force of the inner centering springs should be chosen smaller than the spring force of the holding pliers for the rods to secure them and do not endanger electrical contacting on the holding clamps. Is the lateral pressure of the bars, which the inner springs of the membrane holder absorb, too large, d. H. the centering effect is no longer sufficient around the rods to center, the membranes when the rods are inserted into the shielding device shifted to an eccentric position to avoid damage to prevent the membranes. This ensures the accurate dimming the field lines still possible. In contrast, the gap from elastic Material manufactured membranes in the known rigidly on the shielding device attached shielding membranes by the lateral pressure of the rods on, so that the dimming effect is prevented at this point.

Are inside the lower membrane support and below the membrane either several tapering towards the center and resilient at the Diaphragm holder attached center spring wings or at least three resilient centrally arranged and forming a guide spring bars as inner Centering springs attached, which act on the rods centering by the Pinch rods pushed through the membrane and thereby form a centering guide. The spring bars can in particular be elongated and formed by a membrane holder Level sloping with the free ends one with the center of the Form membrane holder aligned opening through which the rods can be pushed are.

Can also be used as inner centering springs within the lower membrane carrier at least two secured against twisting with one end on the membrane holder Spring bars with a correspondingly twist-proof at the free end of the membrane holder fixed, centering guides can be used. This Spring bars are aligned such that one through by the membrane holder membrane held by push-through rod can be clamped by the spring rods is. Each of the guides are prismatic and essentially parallel to the spring bars are provided guides for the bars.

The inner centering springs located within the upper diaphragm supports can in particular be elongated and on one of the membrane holder formed plane is essentially vertical with the free, by at least 45 °, preferably at least 90 ° and in particular at least 180 °, bent ends one with the center of the membrane holder Form an aligned opening through which the rods can be pushed.

When extending the rods from the anti-dazzle device according to the invention the outer springs on the membrane holders ensure that the membranes center again for the bars entering with the next batch, d. H. spring back to the starting position.

To the device for the treatment of different rod lengths or different geometries of the to be coated and not to be coated Height adjustment devices are provided, with which the membrane carrier with the membrane holders and membranes in are movable in the vertical direction.

a. Greifen der im wesentlichen vertikal ausgerichteten Stäbe mittels geeigneter Haltelemente;

b. Einfahren der Stäbe in einen Badbehälter und in innerhalb mindestens eines Membranträgers angeordnete Membranhalter, wobei der Badbehälter rohrförmige Elektroden und mindestens einen rohrförmigen Membranträger aufweist, in die die Stäbe zumindest teilweise einfahrbar sind;

c. Hindurchfahren des Behandlungsgutes durch jeweils eine zentrale Öffnung in mindestens einer von den Membranhaltern gehaltenen Membran.

The device can be used to carry out a method for partial electrochemical treatment of the rods in immersion systems with the following method steps:

a. Gripping the essentially vertically aligned rods by means of suitable holding elements;

b. Retracting the rods into a bath container and into membrane holders arranged within at least one membrane carrier, the bath container having tubular electrodes and at least one tubular membrane carrier into which the rods can be at least partially inserted;

c. Passing the material to be treated through a central opening in at least one membrane held by the membrane holders.

This does not involve vertically arranged bars and the central openings in the membranes as they pass through the at least one membrane automatically aligned with each other.

Fig. 1a:

eine schematische Darstellung eines Schnitts durch eine Behandlungsstation entsprechend dem Stand der Technik;

Fig. 1b:

eine schematische Darstellung eines Schnitts durch eine starre Maske in einer Behandlungsstation entsprechend dem Stand der Technik;

Fig. 2:

eine schematische Darstellung eines Schnitts durch einen oberen erfindungsgemäßen Membranträger;

Fig. 3:

eine schematische Darstellung eines Schnitts durch einen unteren erfindungsgemäßen Membranträger;

Fig. 4a:

eine schematische Darstellung einer Ausführungsform eines unteren Membranhalters;

Fig. 4b:

eine schematische Darstellung einer anderen Ausführungsform eines unteren Membranhalters.

The invention is described in more detail using the examples in the following figures. Show it:

Fig. 1a:

a schematic representation of a section through a treatment station according to the prior art;

Fig. 1b:

a schematic representation of a section through a rigid mask in a treatment station according to the prior art;

Fig. 2:

a schematic representation of a section through an upper membrane carrier according to the invention;

Fig. 3:

a schematic representation of a section through a lower membrane support according to the invention;

Fig. 4a:

a schematic representation of an embodiment of a lower membrane holder;

Fig. 4b:

is a schematic representation of another embodiment of a lower membrane holder.

1a shows a vertical section through a bath tank with several conventional electrolytic individual cells for chrome-plating rods. In Fig. 1b , a single conventional electrolytic single cell within the bath container of Fig. 1a is shown in detail and cut vertically.

A bath container 14 is filled with electrolyte up to the edge zone 33 . Tubular electrodes 30 are installed in the bath container and are electrically conductively connected to a DC power source, not shown. Furthermore, in and on the bath container 14 there are two panel supports 17 and 25 which can be adjusted independently of one another in the vertical direction. On the goods carrier 1 , which is held in the correct position in the bathroom by the goods carrier support 2 , there are holding tongs 3 which contact and hold the rods 10 electrically. By immersing the goods carrier 1 in the tubular electrode 30, the rods 10 attached cuffs 25 pierce the first rigidly to the vertically adjustable diaphragm carrier 27 in the upper membrane support 26 (Fig. 1b). When the product carrier 1 is further lowered, the rods 10 also pierce the sleeve 24 of the lower membrane carrier 23 ( FIG. 1b ), which is fastened to the lower panel carrier 17 . Both the lower diaphragm support 17 with the diaphragm support 23 and the sleeves 24 ( FIG. 1b ) and the upper diaphragm support 25 with the diaphragm support 26 and the sleeves 27 can be adjusted in height by the adjusting devices 20 and 28 in accordance with the requirements of the rods 10 . To further reduce the current density in the lower region of the rods, as shown in FIG. 1b , conductive auxiliary cathodes 22 can be attached, which are pressed against the retracted material to be treated 10 by springs 21 and thus greatly increase the cathodic surface or the cathodic current density reduce that no deposition takes place in the lower shielded area. Rods 10 with different dimensions and different requirements for the location of the partial coating / treatment on the bathroom can thus be processed.

In the following, reference is made to the embodiments according to the invention. As far as certain parts of the device are not shown in FIGS . 2 to 4 , reference is made to the corresponding parts with the corresponding reference numbers in FIGS . 1a and 1b . In this respect, FIGS. 1a and 1b also represent device features according to the invention.

In FIG. 2, the upper membrane support according to the invention 26 is in a vertical sectional view as a detail of a Einzelgalvanisierzelle within the plating tank 14 not shown (see Fig. 1a) is shown. The tubular membrane support 26 is fastened to the upper diaphragm support 25 , which is adjusted to the correct position for the rods to be produced via a height adjustment device 28 (not shown here) (see FIG. 1a ).

The adjustment of the aperture support 25 simultaneously causes the electrically non-conductive tube of the membrane support 26 to be inserted into the insoluble electrode 30, which is shown in sections, and thus to blank the unnecessary length of the electrode. When the rods 10 are moved into the bath container 14 , the panel support 25 can advantageously be in the upper position.

The panel support 25 and all parts immersed in the bath are made of chemically resistant material. On electrically non-conductive materials such. B. PVC, PVDF, PTFE available. As an electrically conductive material z. B. titanium or lead can be used.

When the goods carrier 1 , which is not shown here, is lowered, the rod 10 is first moved into the area of the inner centering springs 7 , which exert a centering pressure on the rod 10 and align it when it hangs downward in an off-center position. If the spring pressure is not sufficient for aligning the rod 10 , the membrane holder 5 held with the outer centering springs 19 is displaced in the horizontal direction so that it adapts to the rod position in order to prevent damage or expansion of the sensitive membrane 9 . In order to ensure the function of the membrane holder 5 , the cage cover 12 and the cage bottom 16 are attached to the tubular membrane support 26 in such a way that the membrane holder 5 can move freely in the horizontal (radial) direction, but is held sufficiently firmly in the vertical direction. After the rod 10 has been lowered into its lowermost position, the upper diaphragm support 25 can be moved down into the shielding position specified by the rod construction. In a preferred embodiment, the shielding membrane 9, which lies closely against the rod 10 , curves conically upwards on the inside. This leads to a reduction in the bone effect (formation of a thickened electrodeposited layer) at the ends of the rod 10 .

After the treatment, the rod 10 is extended vertically upwards out of the electroplating cell. As soon as the rod 10 has moved out of the membrane 9 , the membrane holder 5 is centered again in the middle of the membrane carrier 26 via the outer springs 19 .

FIG. 3 shows the lower membrane carrier 23 according to the invention with a small section of the panel carrier 17 in a vertical section through an individual electroplating cell within the bath container 14 (not shown here) (see FIG. 1a ). The tubular membrane carrier 23 is fastened to the lower diaphragm carrier 17 and can be brought to the correct lower setting for the rods 10 to be produced via the height adjustment device 20 (not shown here) (see FIG. 1a ). The height of the membrane carrier 23 is preferably set before the sinking of the product carrier 1 , not shown.

The basic structure of the lower shielding device corresponds to the upper shielding device from FIG. 2 . The membrane holder 4 with the outer centering springs 18, the cage cover 11, the cage bottom 15 and the inner centering springs 6 are also present here. The inner centering springs 6 are, however, arranged below the membrane 8 in order to avoid a disruptive influence on the field line concentration in the electroplating area of the rod 10 . It is important here that the distance of the centering spring 6 from the membrane 8 is not chosen too large, in order to prevent damage to the membrane 8 by the rod 10 which has not yet been centered or the correct position of the membrane 8 . After the rod 10 is retracted into the cell by the upper shielding device, when it is lowered further it first hits the membrane 8, passes through it against the inner centering spring 6 and becomes necessary (if the centering effect of the upper shielding device is not sufficient) ) centered. If the pressure on the spring 6 is too great, the diaphragm holder 4 with the diaphragm 8 is also displaced horizontally (radially) against the spring force of the outer centering springs 18 in order to open the diaphragm 8 on the side not pressed by the rod 10 or to damage it to prevent. This ensures that the rod end is shielded to the edge. As with the upper shielding device, the outer centering springs 18 after the rods 10 have been extended from the lower shielding device ensure that the membrane holder 4 moves back into its starting position, ie, centers itself again.

Depending on the requirements of the rods 10 , only one upper, one lower or both shielding devices (top and bottom) can be used. Likewise, a combination of the shielding devices above / below is possible in accordance with the proposed invention and the prior art.

4a shows a preferred embodiment of a lower membrane holder 4 in a top view and in a side view. The outer rod-shaped centering springs 18 are attached tangentially to the outer circumference of the cylindrical membrane holder 4 . The inner centering springs 29 are wing-shaped and crossed or inclined towards the center of the membrane holder 4 , so that there are three conical surfaces on the inside, against which the non-central hanging rod 10 (see FIG. 3 ) presses when entering the device. When the rod 10 is lowered further, the wing-shaped centering springs 29 spring downwards and outwards. This special embodiment has the advantage that, because of the lower demands on the spring properties, abrasion-resistant plastics can also be used as materials with ideal shielding properties for the inner centering springs 29 .

A membrane holder 4 is again shown in FIG. 4b . Compared to the membrane holder 4 of Fig. 4a , a different shape of the inner centering springs is provided. The centering springs each consist of a spring bar 32, which is secured on the outside on the membrane holder 4 against rotation. On the inside of the spring bar 32 , a prism-shaped guide 31 is attached, which is also secured against rotation. The direction of installation of the spring rod 32 points obliquely downward away from the membrane holder. In conjunction with the prism guides 31, both springs 32 bring about a good centering of the rods 10 (see FIG. 3 ).

The inner centering springs 29, 32 of FIGS. 4 a and 4 b are also suitable for use on the upper membrane holders 5 . In this case, as shown in FIG. 2 , the centering springs 29, 32 must be arranged above the membrane holder 5 .

LIST OF REFERENCE NUMBERS

1

goods carriers

2

Were supporting seat

3

holding forceps

4

Membrane holder below

5

Membrane holder at the top

6

inner center spring below

7

inner centering spring at the top

8th

Shielding membrane below

9

Shielding membrane at the top

10

Rod (material to be treated)

11

Cage cover in the lower shielding device

12

Cage cover in the upper shielding device

13

Plastic plate

14

bath container

15

Cage bottom in lower shielding device

16

Cage bottom in the upper shielding device

17

lower panel support

18

outer centering spring for shielding membrane below

19

outer centering spring for shielding membrane at the top

20

Height adjustment device for shielding device below

21

compression spring

22

auxiliary cathode

23

tubular membrane support below

24

Cuff below

25

upper panel support

26

tubular membrane support on top

27

Cuff top

28

Height adjustment device for shielding device above

29

wing-shaped centering spring

30

electrode

31

Prismatic guidance

32

spring bar

33

border zone

Claims (11)

1. Apparatus for the partial electrochemical treatment of bar-shaped material to be treated in immersion bath systems, which apparatus includes

   a. at least one bath container,

   b. tubular electrodes and at least one tubular diaphragm carrier, into which at least some of the material to be treated can be introduced, in the at least one bath container, and

   c. diaphragm holders disposed internally of the at least one diaphragm carrier,

   characterised in that at least one respective cage is provided internally of the at least one tubular diaphragm carrier (23,26) and is disposed in such a manner that the material to be treated (10) can be pushed through the cage, each cage is formed by at least one respective cage cover (11,12) and at least one cage base (15,16), a diaphragm holder (4,5), which holds a diaphragm (8,9), is radially displaceably mounted in each cage between the cage cover (11,12) and the cage base (15,16), and in that at least one respective internal centering spring (6,7,29,32) is provided for guiding the material to be treated (10), and at least one respective external centering spring (18,19) is provided for centering the diaphragm holder (4,5) with the diaphragm (8,9) in the cage.
2. Apparatus according to claim 1, characterised in that at least three internal centering springs (6,7) are secured on each respective diaphragm holder (4,5) and are orientated in such a manner that material to be treated (10), which can be pushed through the diaphragm (8,9) held by the diaphragm holder (4,5), can be clamped in position by the springs (6,7), and the springs (6,7) jointly form a centering guide means for the material to be treated (10).
3. Apparatus according to claim 1, characterised in that at least two resilient bars (32) are provided as the internal centering springs, which bars are secured on the diaphragm holder (4,5) in a non-rotatable manner by one respective end and are orientated in such a manner that material to be treated (10), which can be pushed through the diaphragm (8,9) held by the diaphragm holder (4,5), can be clamped in position by the resilient bars (32), and prismatic guides (31), which extend substantially parallel to the resilient bars (32), for guiding the material to be treated (10) are secured in a non-rotatable manner on the respective free ends of said bars, by means of which a centering guidance for the material to be treated (10) can be accomplished.
4. Apparatus according to claim 1, characterised in that vane-like springs (29) are provided as the internal centering springs, which springs are secured on the diaphragm holder (4,5) with one respective end and are orientated in such a manner that material to be treated (10), which can be pushed through the diaphragm (8,9) held by the diaphragm holder (4,5), can be clamped in position by the springs (29), and the springs (29) jointly form a centering guide means for the material to be treated (10).
5. Apparatus according to claim 4, characterised in that the internal centering springs (6,7) have an elongate configuration and form, with the free ends extending inclinedly away from a plane formed by the diaphragm holder (4,5), an opening which is in alignment with the centre of the diaphragm holder (4,5), and through which opening the material to be treated (10) can be pushed.
6. Apparatus according to claim 4, characterised in that the internal centering springs (6,7) have an elongate configuration and form, with the free ends which are bent-over through at least 45° and lie substantially perpendicularly on a plane formed by the diaphragm holder (4,5), an opening which is in alignment with the centre of the diaphragm holder (4,5), and through which opening the material to be treated (10) can be pushed.
7. Apparatus according to one of the preceding claims, characterised in that leaf springs (18,19), as the external centering springs (18,19), are tangentially secured on the diaphragm holder (4,5).
8. Apparatus according to one of the preceding claims, characterised in that the tubular diaphragm carriers (23,26) are formed from material which is chemically resistant and is at least electrically non-conductive at the surface.
9. Apparatus according to one of the preceding claims, characterised in that the diaphragms (8,9) are formed from chemically resistant, expandable and electrically non-conductive material.
10. Apparatus according to one of the preceding claims, characterised in that the diaphragm carriers (23,26), with the diaphragm holders (4,5) and diaphragms (8,9), are displaceable in the vertical direction via vertically adjusting means (20,28).
11. Method of partially electrochemically treating bar-shaped material to be treated in immersion bath systems, including the following method steps:

    a. gripping substantially vertically orientated material to be treated by means of suitable retaining elements;

    b. introducing the material to be treated into a bath container, including tubular electrodes and at least one tubular diaphragm carrier, into which the material to be treated can be introduced at least partially, and diaphragm holders disposed within the at least one diaphragm carrier; and

    c. passing the material to be treated through a respective central opening in at least one diaphragm held by the diaphragm holders;

    characterised in that non-vertically disposed material to be treated (10) and the central openings are automatically orientated towards one another during the passage through the at least one diaphragm (8,9).

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