EP0514582A1 - Device for electroplating - Google Patents

Device for electroplating Download PDF

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Publication number
EP0514582A1
EP0514582A1 EP91109382A EP91109382A EP0514582A1 EP 0514582 A1 EP0514582 A1 EP 0514582A1 EP 91109382 A EP91109382 A EP 91109382A EP 91109382 A EP91109382 A EP 91109382A EP 0514582 A1 EP0514582 A1 EP 0514582A1
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EP
European Patent Office
Prior art keywords
anode
metal
groove
carrier
metal body
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP91109382A
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German (de)
French (fr)
Inventor
Günther Fellmann
Lothar Remmel
Reinhard Koch
Rüdiger Weinhardt
Niek Haak
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De Nora Deutschland GmbH
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Heraeus Elektrochemie GmbH
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Publication date
Application filed by Heraeus Elektrochemie GmbH filed Critical Heraeus Elektrochemie GmbH
Publication of EP0514582A1 publication Critical patent/EP0514582A1/en
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/10—Electrodes, e.g. composition, counter electrode
    • C25D17/12—Shape or form
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition

Definitions

  • the invention relates to an arrangement for the electrolytic coating of the surface of at least one groove of a metal body which is connected to a negative potential, part of an anode protruding into the groove with play, and the use of such an arrangement.
  • a sacrificial anode made of a metal is provided, the solubility of which is higher than the solubility of the shaped anode, so that the sacrificial anode constantly supplies metal ions which are necessary to maintain the metal ion concentration in the galvanic bath.
  • the shaped anode which is shaped according to the profile of the workpiece to be coated, is made of stainless chromium-nickel steel, which is difficult to dissolve in the electroplating bath.
  • a Such a method is suitable, for example, for galvanizing workpieces in an acidic zinc bath.
  • a general use, for example for permanent use in electroplating baths for chrome plating, is only possible for such a process due to the strong removal of the anode material under economically unfavorable conditions.
  • EP-OS 0 089 475 discloses an anode made of coated valve metal, for example titanium, for the electrolytic extraction of metals or metal oxides, the contact structure of which has, for example, a titanium expanded metal strip.
  • an anode can be used to extract metals, but it cannot be used for the galvanic coating of workpieces with fine structures, such as grooves.
  • the object of the invention is to create an anode which is suitable for the galvanic coating of finely structured areas in workpieces.
  • the anode should be as resistant as possible to the galvanic bath, so that long-term economical operation is possible.
  • a use of the invention for the treatment of pistons in work machines is to be specified.
  • the anode part protruding into the groove consists of expanded metal of valve metal provided with an active surface coating, which is electrically conductively connected to a carrier of valve metal.
  • the surface shape of the carrier is adapted to the surface of the metal body facing it.
  • the uniform current density that can be achieved in this way proves to be advantageous in the areas of the groove to be coated, in particular an annular groove.
  • the carrier forms a cavity composed of several segments.
  • the easy insertion of the parts of the anode protruding into the groove during the assembly process has proven to be advantageous.
  • the parts of the anode protruding into the groove of the metal body consist of folded expanded metal strips attached to the carrier.
  • the relatively simple fastening and contacting of the folded expanded metal strips on the carrier and the easy plastic deformability of the expanded metal strips prove to be advantageous, so that they can be easily formed in a round bending machine by shaping the metal body or by means of paired, movable guide rollers in the metal body Groove can be adjusted.
  • the metal body 1 consists of a cylinder-shaped piston for a thermodynamic machine, for example an internal combustion engine based on the diesel or gasoline engine principle, the piston guided in a cylinder being sealed against the cylinder wall by piston rings. These piston rings are used in ring grooves 2 which have areas 3 which are galvanically chrome-plated for the purpose of improved durability.
  • the cylinder axis of the metal body 1 is designated by the reference number 4.
  • the metal body 1 is connected to the negative potential of a voltage source 6 via a symbolically illustrated terminal 5.
  • the anode 7 comprising the metal body 1 in the form of a cavity consists of a support 8 which is adapted to the surface shape of the metal body 1 and which is designed here in the form of a hollow cylinder which consists of a plurality of cylinder segments.
  • a support 8 which is adapted to the surface shape of the metal body 1 and which is designed here in the form of a hollow cylinder which consists of a plurality of cylinder segments.
  • web-shaped parts 9 with active surface coating are provided, which protrude with play into the ring grooves 2 of the metal body 1.
  • the web-shaped activated parts 9 of the anode 7 consist of rectangular expanded metal strips, the edges 10 of which are electrically and mechanically firmly connected to the support 8 made of titanium sheet by welding points 11. It is also possible to attach the expanded metal strips to the carrier by means of rivet or screw connections.
  • the segment-shaped carrier 8 are adapted by rounding the surface shape of the cylindrical metal body 1, the previously applied parts 9 of expanded metal in the area of their bevels 10 also being deformed corresponding to the carrier, while the web-shaped parts 9 protruding from the carrier 8 while maintaining their previous level are slightly deformed in their expanded metal mesh structure by compression.
  • the arrangement is located in an electrolyte vessel 12, the galvanic bath 13 enclosing the areas of the metal body 1 to be coated.
  • the electrolyte level is denoted by 14.
  • the carrier 8 of the anode is connected to the positive terminal of the voltage source 6 via a symbolically illustrated terminal 15 and a contact bridge 20.
  • Figure 2 shows a segment of the anode 7, wherein on the carrier 8 made of titanium sheet, the parts 9 provided with active surface coating of titanium expanded metal symbolically represented here in the region of their folds 10 are firmly and mechanically connected to the carrier 8 by means of welding points 11.
  • the segment design it is possible to divide the anode into, for example, two sectors, the individual segments each forming a sub-segment of 180 ° of the cylindrical anode 7, as is shown schematically in FIG. 3. However, it is also possible to divide the anode into four sectors, so that each individual segment is designed as a partial segment of 90 ° of the cylindrical cavity.
  • the power connection of the carrier 8 to the positive terminal of the voltage source takes place via a connecting tab 17.
  • FIG. 3 shows a top view of the anode 7 concentrically surrounding the metal body 1, only one sector of the part 9 of the anode 7 consisting of expanded metal being shown to simplify the illustration.
  • the anode 7 consists of two semi-cylindrical individual segments, which are combined by screw connections 18 in the area of the connecting lugs 17 to form a coherent cylindrical cavity.
  • the anode 7 is enclosed by an annular current distributor 19 which forwards the anode current supplied via the connecting lugs 17 to the carriers 8 via contact webs 20.
  • cylindrical pistons are chromed as metal bodies 1 with 5 ring grooves.
  • Pistons with a diameter of 900 mm have an annular groove, the gap of which is about 20 mm deep and wide.
  • the thickness of the part 9 of the anode 7 protruding into the annular groove 2 is in a range from 1.0 to 4.5 mm.
  • a current load of 500 A per ring groove is specified, so that a total output of 2500 A occurs in a cylindrical metal body to be coated with 5 ring grooves.
  • a solution containing approximately 250 g / l chromic acid and approximately 2.5 g / l sulfate is used as the galvanic bath.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

To electroplate the grooves of a metal body (1), in particular to chromium-plate annular grooves (2) in internal combustion engine pistons, an anode part (9) which is made of expanded titanium metal having an active surface coating and connected in a mechanically rigid and electrically conducting way to a titanium-sheet carrier (8) extends into the groove. <IMAGE>

Description

Die Erfindung betrifft eine Anordnung zur elektrolytischen Beschichtung der Oberfläche wenigstens einer Nut eines Metall-Körpers, der an ein negatives Potential angeschlossen ist, wobei ein Teil einer Anode in die Nut mit Spiel hineinragt sowie die Verwendung einer solchen Anordnung.The invention relates to an arrangement for the electrolytic coating of the surface of at least one groove of a metal body which is connected to a negative potential, part of an anode protruding into the groove with play, and the use of such an arrangement.

Aus der CH-PS 602 946 ist ein Galvanisierungsverfahren für die Herstellung galvanischer Überzüge auf Oberflächen von Profilmaterialwerkstücken bekannt, wobei zur Beschichtung eines mit einer Nut versehenen Werkstückes im Nutbereich der elektrochemisch aktive Teil einer Anode als ein in die Nut ragender Vorsprung ausgebildet ist und die Anode aus einem im galvanischen Bad schwer bzw. unlöslichen Werkstoff besteht, wobei das Werkstück als Kathode geschaltet ist. Zusätzlich zu dieser als Formanode bezeichneten Elektrode ist eine Opferanode aus einem Metall vorgesehen, dessen Löslichkeit höher liegt als die Löslichkeit der Formanode, so daß seitens der Opferanode ständig Metallionen nachgeliefert werden, die zur Aufrechterhaltung der Metallionen-Konzentration des galvanischen Bades erforderlich sind. Die nach dem Profil des zu beschichtenden Werkstücks geformte Formanode besteht aus rostfreiem Chromnickelstahl, der im galvanischen Bad schwer löslich ist. Ein solches Verfahren ist beispielsweise zur Verzinkung von Werkstücken in einem sauren Zinkbad geeignet. Eine allgemeine Verwendungsmöglichkeit, beispielsweise zum dauerhaften Einsatz in galvanischen Bädern zur Badverchromung, ist für ein solches Verfahren aufgrund des starken Abtrags des Anodenmaterials nur unter wirtschaftlich ungünstigen Verhältnissen möglich.From CH-PS 602 946 a galvanizing process for the production of galvanic coatings on surfaces of profile material workpieces is known, wherein the electrochemically active part of an anode is designed as a protruding into the groove and the anode for coating a workpiece provided with a groove in the groove area consists of a material which is difficult or insoluble in the galvanic bath, the workpiece being connected as a cathode. In addition to this electrode, which is referred to as a shaped anode, a sacrificial anode made of a metal is provided, the solubility of which is higher than the solubility of the shaped anode, so that the sacrificial anode constantly supplies metal ions which are necessary to maintain the metal ion concentration in the galvanic bath. The shaped anode, which is shaped according to the profile of the workpiece to be coated, is made of stainless chromium-nickel steel, which is difficult to dissolve in the electroplating bath. A Such a method is suitable, for example, for galvanizing workpieces in an acidic zinc bath. A general use, for example for permanent use in electroplating baths for chrome plating, is only possible for such a process due to the strong removal of the anode material under economically unfavorable conditions.

Weiterhin ist aus der EP-OS 0 089 475 eine Anode aus beschichtetem Ventilmetall, beispielsweise Titan, zur elektrolytischen Gewinnung von Metallen oder Metalloxiden bekannt, deren Kontaktstruktur beispielsweise einen Titan-Streckmetallstreifen aufweist. Eine solche Anode ist zwar zur Gewinnung von Metallen einsetzbar, sie kann jedoch nicht zur galvanischen Beschichtung von Werkstücken mit feinen Strukturen, wie beispielsweise Nuten, eingesetzt werden.Furthermore, EP-OS 0 089 475 discloses an anode made of coated valve metal, for example titanium, for the electrolytic extraction of metals or metal oxides, the contact structure of which has, for example, a titanium expanded metal strip. Such an anode can be used to extract metals, but it cannot be used for the galvanic coating of workpieces with fine structures, such as grooves.

Die Erfindung stellt sich die Aufgabe, eine Anode zu schaffen, welche zur galvanischen Beschichtung feinstrukturierter Bereiche in Werkstücken geeignet ist. Darüber hinaus soll die Anode gegenüber dem galvanischen Bad möglichst resistent sein, so das ein lang andauernder wirtschaftlicher Betrieb möglich ist. Weiterhin soll eine Verwendung der Erfindung für die Behandlung von Kolben in Arbeitsmaschinen angegeben werden.The object of the invention is to create an anode which is suitable for the galvanic coating of finely structured areas in workpieces. In addition, the anode should be as resistant as possible to the galvanic bath, so that long-term economical operation is possible. Furthermore, a use of the invention for the treatment of pistons in work machines is to be specified.

Die Aufgabe wird dadurch gelöst, daß der in die Nut hineinragende Anoden-Teil aus mit aktiver Oberflächenbeschichtung versehenem Streckmetall aus Ventilmetall besteht, der elektrisch leitend mit einem Träger aus Ventilmetall verbunden ist.The object is achieved in that the anode part protruding into the groove consists of expanded metal of valve metal provided with an active surface coating, which is electrically conductively connected to a carrier of valve metal.

Hinsichtlich der Verwendung einer solchen Anordnung wird diese für die Verchromung von Nuten, insbesondere Ringnuten, in Kolben von thermodynamischen Arbeitsmaschinen eingesetzt.With regard to the use of such an arrangement, it is used for the chrome plating of grooves, in particular ring grooves, in pistons of thermodynamic machines.

In einer bevorzugten Ausgestaltung der Erfindung ist die Oberflächenform des Trägers der ihr zugekehrten Oberfläche des Metallkörpers angepaßt. Als vorteilhaft erweist sich die hierdurch erzielbare gleichmäßige Stromdichte in den zu beschichtenden Bereichen der Nut, insbesondere Ringnut.In a preferred embodiment of the invention, the surface shape of the carrier is adapted to the surface of the metal body facing it. The uniform current density that can be achieved in this way proves to be advantageous in the areas of the groove to be coated, in particular an annular groove.

Weiterhin bildet der Träger einen aus mehreren Segmenten zusammengesetzten Hohlraum. Als vorteilhaft erweist sich hierbei die leichte Einführbarkeit der in die Nut hineinragenden Teile der Anode während des Zusammensetz-Vorganges.Furthermore, the carrier forms a cavity composed of several segments. The easy insertion of the parts of the anode protruding into the groove during the assembly process has proven to be advantageous.

Weiterhin bestehen die in die Nut des Metallkörpers ragenden Teile der Anode aus am Träger befestigten abgekanteten Streckmetallstreifen. Hier erweist sich die verhältnismäßig einfache Befestigung und Kontaktierung der abgekanteten Streckmetallstreifen am Träger sowie die leichte plastische Verformbarkeit der Streckmetallstreifen als vorteilhaft, so daß sie auf einfache Weise in einer Rundbiegemaschine der Formgebung des Metallkörpers bzw. mittels paarweise angeordneter, beweglicher Führungsrollen der in dem Metallkörper befindlichen Nut angepaßt werden können.Furthermore, the parts of the anode protruding into the groove of the metal body consist of folded expanded metal strips attached to the carrier. Here, the relatively simple fastening and contacting of the folded expanded metal strips on the carrier and the easy plastic deformability of the expanded metal strips prove to be advantageous, so that they can be easily formed in a round bending machine by shaping the metal body or by means of paired, movable guide rollers in the metal body Groove can be adjusted.

Die Verwendung zur Verchromung von Ringnuten in Kolben von thermodynamischen Arbeitsmaschinen erweist sich als besonders vorteilhaft, da neben hoher Stromdichte in dem zu beschichtenden Ringnutenbereich auch eine einfache Handhabung durch Sektorenaufteilung möglich ist und eine Kontamination von galvanischem Bad sowie eine Verunreinigung der Chromschicht im Ringnutbereich verhindert wird.The use for the chrome plating of ring grooves in pistons of thermodynamic machines has proven to be particularly advantageous, since in addition to high current density in the ring groove area to be coated, easy handling by sector division is also possible and contamination of galvanic bath and contamination of the chrome layer in the ring groove area is prevented.

Im folgenden ist der Gegenstand anhand der Zeichnung näher erläutert.

Figur 1
zeigt im Längsschnitt eines als Kolben einer thermodynamischen Arbeitsmaschine ausgebildeten Metallkörpers zusammen mit einem Längsschnitt der Anode;
Figur 2
zeigt ein Segment der Anode, deren aktivierte Teile aus Streckmetallstreifen bestehen.
Figur 3
zeigt in einer Draufsicht eine aus Segmenten zusammengesetzte Anode, in die als Metallkörper ein zylindrischer Kolben eingesetzt ist.
The object is explained in more detail below with the aid of the drawing.
Figure 1
shows a longitudinal section of a metal body designed as a piston of a thermodynamic machine together with a longitudinal section of the anode;
Figure 2
shows a segment of the anode, the activated parts of which consist of expanded metal strips.
Figure 3
shows a plan view of an anode composed of segments, in which a cylindrical piston is inserted as a metal body.

Gemäß Figur 1 besteht der Metallkörper 1 aus einem zylindrisch ausgebildeten Kolben für eine thermodynamische Arbeitsmaschine, beispielsweise eine Verbrennungsmaschine nach dem Diesel- oder Otto-Motor-Prinzip, wobei der in einem Zylinder geführte Kolben gegenüber der Zylinderwand durch Kolbenringe abzudichten ist. Diese Kolbenringe werden in Ringnuten 2 eingesetzt, welche zwecks verbesserter Haltbarkeit Bereiche 3 aufweisen, die galvanisch verchromt sind. Die Zylinderachse des Metallkörpers 1 ist mit der Bezugsziffer 4 bezeichnet. Der Metallkörper 1 ist über eine symbolisch dargestellte Anschlußklemme 5 mit dem negativen Potential einer Spannungsquelle 6 verbunden. Die in Form eines Hohlraumes den Metallkörper 1 umfassende Anode 7 besteht aus einem der Oberflächenform des Metallkörpers 1 angepaßten Träger 8, der hier in Form eines Hohlzylinders ausgebildet ist, welcher aus mehreren Zylindersegmenten besteht. Auf der der Oberfläche des Metallkörpers 1 zugewandten Seite des Trägers 8 sind stegförmig ausgebildete mit aktiver Oberflächenbeschichtung versehene Teile 9 vorgesehen, welche mit Spiel in die Ring-Nuten 2 des Metallkörpers 1 hineinragen. Die stegförmigen aktivierten Teile 9 der Anode 7 bestehen dabei aus rechtwinklig abgekanteten Streckmetallstreifen, deren Abkantungen 10 mit dem aus Titanblech bestehenden Träger 8 durch Schweißstellen 11 elektrisch und mechanisch fest verbunden sind. Es ist auch möglich, die Streckmetallstreifen auf dem Träger mittels Niet- oder Schraubverbindungen zu befestigen. Die segmentförmigen Träger 8 sind dabei durch Rundung der Oberflächengestalt des zylindrischen Metallkörpers 1 angepaßt, wobei die zuvor aufgebrachten Teile 9 aus Streckmetall im Bereich ihrer Abkantungen 10 dem Träger entsprechend ebenfalls verformt sind, während die vom Träger 8 abstehenden stegförmigen Teile 9 unter Beibehaltung ihrer bisherigen Ebene in ihrer Streckmetall-Netzstruktur durch Stauchung geringfügig verformt sind.According to FIG. 1, the metal body 1 consists of a cylinder-shaped piston for a thermodynamic machine, for example an internal combustion engine based on the diesel or gasoline engine principle, the piston guided in a cylinder being sealed against the cylinder wall by piston rings. These piston rings are used in ring grooves 2 which have areas 3 which are galvanically chrome-plated for the purpose of improved durability. The cylinder axis of the metal body 1 is designated by the reference number 4. The metal body 1 is connected to the negative potential of a voltage source 6 via a symbolically illustrated terminal 5. The anode 7 comprising the metal body 1 in the form of a cavity consists of a support 8 which is adapted to the surface shape of the metal body 1 and which is designed here in the form of a hollow cylinder which consists of a plurality of cylinder segments. On the side of the carrier 8 facing the surface of the metal body 1, web-shaped parts 9 with active surface coating are provided, which protrude with play into the ring grooves 2 of the metal body 1. The web-shaped activated parts 9 of the anode 7 consist of rectangular expanded metal strips, the edges 10 of which are electrically and mechanically firmly connected to the support 8 made of titanium sheet by welding points 11. It is also possible to attach the expanded metal strips to the carrier by means of rivet or screw connections. The segment-shaped carrier 8 are adapted by rounding the surface shape of the cylindrical metal body 1, the previously applied parts 9 of expanded metal in the area of their bevels 10 also being deformed corresponding to the carrier, while the web-shaped parts 9 protruding from the carrier 8 while maintaining their previous level are slightly deformed in their expanded metal mesh structure by compression.

Die Anordnung befindet sich in einem Elektrolyt-Gefäß 12, wobei das galvanische Bad 13 die zu beschichtenden Bereiche des Metallkörpers 1 umschließt. Der Elektrolyt-Pegel ist mit 14 bezeichnet. Der Träger 8 der Anode ist über eine symbolisch dargestellte Klemme 15 und einen Kontakt-Steg 20 mit der positiven Klemme der Spannungsquelle 6 verbunden.The arrangement is located in an electrolyte vessel 12, the galvanic bath 13 enclosing the areas of the metal body 1 to be coated. The electrolyte level is denoted by 14. The carrier 8 of the anode is connected to the positive terminal of the voltage source 6 via a symbolically illustrated terminal 15 and a contact bridge 20.

Figur 2 zeigt ein Segment der Anode 7, wobei auf dem aus Titanblech bestehenden Träger 8 die mit aktiver Oberflächenbeschichtung versehenen Teile 9 aus hier symbolisch dargestelltem Titan-Streckmetall im Bereich ihrer Abkantungen 10 mittels Schweißstellen 11 mit dem Träger 8 elektrisch und mechanisch fest verbunden sind. Aufgrund der Segmentbauweise ist es möglich, die Anode in beispielsweise zwei Sektoren aufzuteilen, wobei die Einzel-Segmente jeweils ein Teil-Segment von 180° der zylindrisch ausgebildeten Anode 7 bilden, wie dies in Figur 3 schematisch dargestellt ist. Es ist jedoch auch möglich, die Anode in vier Sektoren aufzuteilen, so daß jedes Einzelsegment als ein Teilsegment von 90° des zylindrischen Hohlraums ausgebildet ist.Figure 2 shows a segment of the anode 7, wherein on the carrier 8 made of titanium sheet, the parts 9 provided with active surface coating of titanium expanded metal symbolically represented here in the region of their folds 10 are firmly and mechanically connected to the carrier 8 by means of welding points 11. Because of the segment design, it is possible to divide the anode into, for example, two sectors, the individual segments each forming a sub-segment of 180 ° of the cylindrical anode 7, as is shown schematically in FIG. 3. However, it is also possible to divide the anode into four sectors, so that each individual segment is designed as a partial segment of 90 ° of the cylindrical cavity.

Der Stromanschluß des Trägers 8 an die positive Klemme der Spannungsquelle erfolgt über eine Anschlußfahne 17.The power connection of the carrier 8 to the positive terminal of the voltage source takes place via a connecting tab 17.

Figur 3 zeigt in einer Draufsicht die den Metallkörper 1 konzentrisch umfassende Anode 7, wobei zur Vereinfachung der Darstellung nur ein Sektor des aus Streckmetall bestehenden Teils 9 der Anode 7 gezeigt ist. Die Anode 7 besteht aus zwei halbzylindrischen Einzel-Segmenten, die durch Schraubverbindungen 18 im Bereich der Anschlußfahnen 17 zu einem zusammenhängenden zylindrischen Hohlraum zusammengefaßt sind. Die Anode 7 wird von einem ringförmigen Stromverteiler 19 umfaßt, der den über die Anschlußfahnen 17 zugeführten Anodenstrom über Kontakt-Stege 20 an die Träger 8 weiterleitet.FIG. 3 shows a top view of the anode 7 concentrically surrounding the metal body 1, only one sector of the part 9 of the anode 7 consisting of expanded metal being shown to simplify the illustration. The anode 7 consists of two semi-cylindrical individual segments, which are combined by screw connections 18 in the area of the connecting lugs 17 to form a coherent cylindrical cavity. The anode 7 is enclosed by an annular current distributor 19 which forwards the anode current supplied via the connecting lugs 17 to the carriers 8 via contact webs 20.

In der Praxis werden beispielsweise zylindrisch ausgebildete Kolben als Metallkörper 1 mit 5 Ringnuten verchromt. Kolben mit einem Durchmesser von 900 mm weisen eine Ringnut auf, deren Spalt eine Tiefe und Breite von jeweils ca. 20 mm beträgt. Die Dicke des in die Ringnut 2 hineinragenden Teils 9 der Anode 7 liegt dabei in einem Bereich von 1,0 bis 4,5 mm. In der Praxis wird eine Strombelastung von 500 A pro Ringnut angegeben, so daß bei einem zu beschichtenden zylindrischen Metallkörper mit 5 Ringnuten eine Gesamtleistung von 2500 A auftritt. Als galvanisches Bad wird dabei eine Lösung verwendet, die ca. 250 g/l Chromsäure und ca. 2,5 g/l Sulfat enthält.In practice, for example, cylindrical pistons are chromed as metal bodies 1 with 5 ring grooves. Pistons with a diameter of 900 mm have an annular groove, the gap of which is about 20 mm deep and wide. The thickness of the part 9 of the anode 7 protruding into the annular groove 2 is in a range from 1.0 to 4.5 mm. In practice, a current load of 500 A per ring groove is specified, so that a total output of 2500 A occurs in a cylindrical metal body to be coated with 5 ring grooves. A solution containing approximately 250 g / l chromic acid and approximately 2.5 g / l sulfate is used as the galvanic bath.

Claims (6)

Anordnung zur galvanischen Beschichtung der Oberfläche wenigstens einer Nut eines Metall-Körpers, der an ein negatives Potential angeschlossen ist, wobei ein Teil einer Anode in die Nut mit Spiel hineinragt, dadurch gekennzeichnet, daß der in die Nut (2) hineinragende Anoden-Teil (9) aus mit aktiver Oberflächenbeschichtung versehenem Streckmetall aus Ventilmetall besteht, der elektrisch leitend mit einem Träger (8) aus Ventilmetall verbunden ist.Arrangement for the galvanic coating of the surface of at least one groove of a metal body which is connected to a negative potential, part of an anode protruding into the groove with play, characterized in that the anode part (protruding into the groove (2) 9) consists of expanded metal made of valve metal with an active surface coating, which is connected in an electrically conductive manner to a support (8) made of valve metal. Anordnung nach Anspruch 1, dadurch gekennzeichnet, daß die Oberflächen-Form des Trägers (8) der ihr zugekehrten Oberfläche des Metallkörpers (1) angepaßt ist.Arrangement according to claim 1, characterized in that the surface shape of the carrier (8) is adapted to the surface of the metal body (1) facing it. Anordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Träger (8) aus mehreren Segmenten einen Hohlraum bildend zusammengesetzt ist.Arrangement according to claim 1 or 2, characterized in that the carrier (8) is composed of a plurality of segments forming a cavity. Anordnung nach einem oder mehreren der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die in die Nut (2) des Metallkörpers (1) ragenden Teile (9) der Anode (7) aus am Träger (8) befestigten, abgekanteten Streckmetallstreifen bestehen.Arrangement according to one or more of Claims 1 to 3, characterized in that the parts (9) of the anode (7) which protrude into the groove (2) of the metal body (1) consist of bent, expanded metal strips fastened to the carrier (8). Anordnung nach einem oder mehreren der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß der Träger (8) Schlitze aufweist, in die Stege aus Streckmetall eingesteckt sind, wobei die Stege über eigene Kontaktierungsmittel mit der Anoden-Stromversorgung verbunden sind.Arrangement according to one or more of Claims 1 to 4, characterized in that the carrier (8) has slots into which webs made of expanded metal are inserted, the webs being connected to the anode power supply via their own contacting means. Verwendung einer Anordnung nach einem oder mehreren der Ansprüche 1 bis 5 für die Verchromung von Nuten, insbesondere Ring-Nuten (2) in Kolben von thermodynamischen Arbeitsmaschinen.Use of an arrangement according to one or more of claims 1 to 5 for the chrome plating of grooves, in particular ring grooves (2) in pistons of thermodynamic machines.
EP91109382A 1990-09-03 1991-06-07 Device for electroplating Ceased EP0514582A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4027834 1990-09-03
DE19904027834 DE4027834A1 (en) 1990-09-03 1990-09-03 Appts. for electroplating grooves in metal body - has anode of expanded titanium@ with active surface coating projecting into groove and fixed to titanium@ carrier

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EP0514582A1 true EP0514582A1 (en) 1992-11-25

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EP91109382A Ceased EP0514582A1 (en) 1990-09-03 1991-06-07 Device for electroplating

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004044270A1 (en) * 2002-11-11 2004-05-27 De Nora Elettrodi S.P.A. Anode for electrometallurgical applications
KR100456731B1 (en) * 2002-04-20 2004-11-10 윤성환 Piston crown electroplating apparatus
CN101492831B (en) * 2008-01-23 2010-10-06 富葵精密组件(深圳)有限公司 Anode apparatus for electroplating and electroplating apparatus comprising the same
CN101694006B (en) * 2009-10-19 2011-01-05 江阴长电先进封装有限公司 Electroplating anode device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4225961C5 (en) * 1992-08-06 2011-01-27 Atotech Deutschland Gmbh Apparatus for electroplating, in particular copper plating, flat plate or arched objects

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DE1055913B (en) * 1956-04-23 1959-04-23 Schmidt Gmbh Karl Arrangement of the anodes for the galvanizing of ring grooves that run parallel to one another, especially in pistons for internal combustion engines and compressors
EP0336071A1 (en) * 1988-03-31 1989-10-11 Eltech Systems Corporation Massive anode as a mosaic of modular anodes

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US3915835A (en) * 1973-11-05 1975-10-28 Ford Motor Co Method of improving plating distribution of elnisil coatings
CH602946A5 (en) * 1974-07-31 1978-08-15 Bbc Brown Boveri & Cie
EP0089457A3 (en) * 1982-03-23 1986-01-22 Texas Instruments Incorporated Avalanche fuse element as programmable memory

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Publication number Priority date Publication date Assignee Title
DE1055913B (en) * 1956-04-23 1959-04-23 Schmidt Gmbh Karl Arrangement of the anodes for the galvanizing of ring grooves that run parallel to one another, especially in pistons for internal combustion engines and compressors
EP0336071A1 (en) * 1988-03-31 1989-10-11 Eltech Systems Corporation Massive anode as a mosaic of modular anodes

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Band 133, Nr. 2, Februar 1986, Seiten 346-349; F. HINE et al.: "A platinized titanium anode for chromium electroplating" *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100456731B1 (en) * 2002-04-20 2004-11-10 윤성환 Piston crown electroplating apparatus
WO2004044270A1 (en) * 2002-11-11 2004-05-27 De Nora Elettrodi S.P.A. Anode for electrometallurgical applications
CN101492831B (en) * 2008-01-23 2010-10-06 富葵精密组件(深圳)有限公司 Anode apparatus for electroplating and electroplating apparatus comprising the same
CN101694006B (en) * 2009-10-19 2011-01-05 江阴长电先进封装有限公司 Electroplating anode device

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