Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/02—Electroplating of selected surface areas
  • C25D5/022—Electroplating of selected surface areas using masking means
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D7/00—Electroplating characterised by the article coated
  • C25D7/04—Tubes; Rings; Hollow bodies

Definitions

• the invention relates to a device and a method for partial treatment, namely electroplating, electrochemical etching or electrochemical cleaning, of rod-shaped items to be treated in immersion bath systems, namely electroplating, etching and cleaning systems.
• 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 rods, are known. These rods can be tapered at one or both ends and / or threaded. An example of this are cylinders for vehicle shock absorbers.
• the invention is not limited to the treatment of round bars. It is also suitable for the treatment of bars with a different cross-section.
• the electrochemical treatment of the rods is used, for example, in shock absorber cylinders to improve the wear and corrosion properties.
• the rods are only electrolytically coated with hard chrome on the surfaces that are stressed during operation.
• the other parts of the rods should remain uncoated or should be partially covered with a thin flash chrome layer as a temporary surface protection.
• the surface is previously electrochemically etched.
• Insoluble electrodes are preferably used for both process steps. Between the individual treatment steps, the bars are rinsed in electroplating systems.
• a transport device ensures that the rods are transported from treatment station to treatment station.
• the ends For the partial treatment of the bars in the middle of the bar, the ends must be masked, ie shielded in such a way that no metal or flash chrome is deposited as temporary protection on these precisely predetermined areas.
• the boundaries between the deposition area and the areas that are not to be coated are generally closely tolerated.
• the uncoated area must, for example, pass into the coated area within only ⁇ 1 millimeter.
• the layer to be deposited must be uniformly thick up to this limit. Edge effects, ie an increase or decrease in layer thickness at the area boundaries, must be avoided. The aim of the precise coating is to avoid subsequent grinding.
• the rods are fastened and treated on racks, the racks in turn being fastened to transportable goods carriers.
• the frames are provided with individual masks in such a way that both rod ends are not coated in the intended area.
• a sufficient number of masks and frames must be available on a galvano system for all existing rod lengths, rod diameters and coating areas. Because the frames are also used to supply the bath current to the bars, they must be metallically conductive. The metal must be protected from galvanizing by plastic coatings.
• adjustable masks with sealing means in the form of end seals are used for each rod at both rod ends to limit the areas to be treated.
• several electrically conductive grippers attached to the goods carrier grip one rod on one side at a time.
• Each rod enters the electrolytic treatment station a single cell, which is formed from the rod and a stationary tubular electrode
• the upper and lower electrolytically active electrode ends are each determined by a tubular, axially adjustable mask.
• the mask ends are closed with a sleeve each.
• the invention is therefore based on the problem of avoiding the disadvantages of the known methods and devices for shielding when galvanizing rods and, in particular, of keeping the workload required for shielding the regions not to be galvanized on rods as small as possible.
• the process should also work properly under production conditions.
• 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 preferably consist of chemically stable and at least on the surface electrically non-conductive material.
• the device has axially adjustable, electrically non-conductive shielding devices in accordance with the dimensions of the material to be treated. At least one shielding device is provided for each rod. For example, a Shielding device may be provided at the lower end of the rod within the bath to avoid the electrochemical treatment of this section of the rod. In this case, the upper part of the rod could remain untreated by not submerging it in the treatment liquid. Shielding devices can also be provided at both ends of the rod.
• the shielding devices each comprise at least one cage within the tubular membrane carrier.
• the cages are arranged such that the material to be treated can be pushed through them, and are each formed by at least one cage lid and at least one cage bottom.
• a membrane holder holding a membrane is mounted in a radially movable manner between the cage cover and the cage bottom in each cage.
• At least one 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, stretchy and electrically non-conductive material.
• the cages are arranged on the side of the shielding device facing the rod center.
• the outer centering springs are preferably rod-shaped as leaf springs and are attached tangentially to the outer surfaces of the membrane holder. They serve to center the membrane holder and the membrane in the cage and counteract the radial pressure of a non-centrically held rod on the membrane and the membrane holder.
• the spring force of the outer centering springs is adapted to the strength of the elastic membranes. It should be chosen so large that the membranes do not open up due to a lateral pressure of the material to be treated or, in extreme cases, tear and the shielding effect is lost at this point.
• the spring force of the inner centering springs should, however, be chosen to be smaller than the spring force of the crimping pliers for the rods in order not to endanger their secure fastening and electrical contacting on the holding pliers. Is the lateral pressure of the rods, which the inner springs of the membrane holder receive, too large, ie the centering effect is no longer sufficient to center the rods, the membranes are moved into an eccentric position when the rods are moved into the shielding device, in order to damage them to prevent the membranes. This enables the accurate measurement of the field lines. In contrast, the membranes made of elastic material gap in the known shielding membranes rigidly attached to the shielding device by the lateral pressure of the rods, so that the shielding effect is prevented at this point.
• centering spring wings tapering to the center and resiliently attached to the diaphragm holder, or at least three resiliently arranged spring bars arranged centrally and forming a guide as inner centering springs, which act on the bars by centering them through pinch the membrane and push through it to form a centering guide.
• the spring bars can in particular be elongated and, with the free ends running away from a plane formed by the membrane holder, form an opening which is aligned with the center of the membrane holder and through which the bars can be pushed.
• At least two spring bars can be used that are secured against rotation with one end on the diaphragm holder, with guides acting in a centering manner that are secured against twisting at the free end of the diaphragm holder.
• These spring bars are aligned in such a way that a bar that can be pushed through the membrane held by the membrane holder can be clamped by the spring bars.
• Prismatic guides for the bars, which run essentially parallel to the spring bars, are provided as guides.
• the inner centering springs arranged inside the upper membrane carrier can in particular be elongated and on an plane formed substantially vertically vertical with the free ends bent by at least 45 °, preferably at least 90 ° and in particular at least 180 ° form an opening aligned with the center of the membrane holder, through which the rods can be pushed.
• the outer springs on the membrane holders ensure that the membranes center again for the rods entering with the next batch, i. H. spring back to the starting position.
• height adjustment devices are provided with which the membrane carriers with the membrane holders and membranes can be moved in the vertical direction.
• 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:
• rods which are not arranged vertically and the central openings in the membranes are passed through the at least one membrane automatically aligned with each other.
• Fig. 1a a schematic representation of a section through a
• Treatment station according to the state of the art; 1b: a schematic representation of a section through a rigid mask in a treatment station according to the prior art;
• FIG. 2 shows a schematic illustration of a section through an upper membrane carrier according to the invention
• 3 a schematic representation of a section through a lower membrane carrier according to the invention
• FIG. 4a a schematic representation of an embodiment of a lower membrane holder
• Fig. 4b 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.
• 1 b shows a detail and a vertical section of a single conventional electrolytic single cell within the bath container of FIG. 1 a.
• 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 connected in an electrically conductive manner to a direct current source (not shown).
• a direct current source not shown.
• panel supports 17 and 25 which can be adjusted independently of one another in the vertical direction.
• Membrane carrier 23 and the cuffs 24 (Fig. 1 b) and the upper diaphragm support 25 with the membrane carrier 26 and the cuffs 27 are, according to the requirements of the rods 10, adjustable in height by the adjusting devices 20 and 28.
• 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 so 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.
• FIGS. 1a and 1b also represent device features according to the invention.
• the upper membrane carrier 26 according to the invention is in a vertical
• FIG. 1a Sectional drawing as a section of an individual electroplating cell shown in the bath container 14, not shown here (see Fig. 1a).
• 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 diaphragm support 25 causes at the same time that the electrically non-conductive tube of the diaphragm support 26 is cut out in the insoluble electrode 30 inserted and thus dimmed the unnecessary length of the electrode.
• 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.
• electrically non-conductive materials such as B. PVC, PVDF, PTFE available.
• As an electrically conductive material z. B. titanium or lead can be used.
• the rod 10 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 downwards 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 such that the membrane holder 5 can move freely in the horizontal (radial) direction, but is held sufficiently firmly in the vertical direction.
• the upper diaphragm support 25 can be moved down into the shielding position specified by the rod construction.
• 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.
• 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 support 23 is fastened to the lower diaphragm support 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 diaphragm 8 in order to be a disturbing one
• 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.
• the rod 10 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 membrane holder 4 with the membrane 8 is also against the here
• the spring force of the outer centering spring 18 is displaced horizontally (radially) in order to prevent the membrane 8 from opening up on the side not pressed by the rod 10 or preventing damage. This ensures that the rod end is shielded to the edge.
• the outer centering springs 18 after the rods 10 have moved out of the lower shielding device ensure that the membrane holder 4 moves back into its starting position, ie, centers itself again.
• only one upper, one lower or both shielding devices top and bottom can be used.
• a combination of the shielding devices above / below is possible in accordance with the proposed invention and the prior art.
• 4a is a preferred embodiment of a lower membrane holder
• 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 arranged towards the center of the diaphragm holder 4 or arranged obliquely, so that three conical surfaces are formed inside, against which the non-centric hanging rod 10 (see FIG. 3) presses when entering the device.
• the wing-shaped centering springs 29 spring downwards and outwards.
• a membrane holder 4 is again shown in FIG. 4b.
• the centering springs each consist of a spring bar 32, which is attached to the outside of the diaphragm holder 4 so that it cannot rotate.
• 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.
• 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 holder 5.
• the inner centering springs 29, 32 of FIGS. 4 a and 4 b are also suitable for use on the upper membrane holder 5.
• the inner centering springs 29, 32 of FIGS. 4 a and 4 b are also suitable for use on the upper membrane holder 5.
• the inner centering springs 29, 32 of FIGS. 4 a and 4 b are also suitable for use on the upper membrane holder 5.
• the inner centering springs 29, 32 of FIGS. 4 a and 4 b are also suitable for use on the upper membrane holder 5.

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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)
• Coating Apparatus (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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• 1998
  • 1998-08-21 DE DE19837973A patent/DE19837973C1/de not_active Expired - Fee Related
• 1999
  • 1999-07-23 EP EP99950440A patent/EP1115912B1/fr not_active Expired - Lifetime
  • 1999-07-23 ES ES99950440T patent/ES2173001T3/es not_active Expired - Lifetime
  • 1999-07-23 JP JP2000566492A patent/JP4317661B2/ja not_active Expired - Fee Related
  • 1999-07-23 AT AT99950440T patent/ATE214746T1/de active
  • 1999-07-23 US US09/763,417 patent/US6508926B1/en not_active Expired - Lifetime
  • 1999-07-23 DE DE59901033T patent/DE59901033D1/de not_active Expired - Lifetime
  • 1999-07-23 WO PCT/DE1999/002311 patent/WO2000011245A2/fr not_active Ceased

Non-Patent Citations (1)

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