Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D13/00—Electrophoretic coating characterised by the process
  • C25D13/12—Electrophoretic coating characterised by the process characterised by the article coated
  • C25D13/14—Tubes; Rings; Hollow bodies
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D13/00—Electrophoretic coating characterised by the process
  • C25D13/22—Servicing or operating apparatus or multistep processes

Definitions

• the invention relates to a method, a device and an apparatus for surface treatment, such as cleaning and / or coating of bodies of metal cans, preferably of Al or its alloys, more particularly of bodies of cans obtained by stamping. , stamping-drawing or by impact spinning.
• These boxes are generally prepared before final filling, on their internal and / or external walls, by cleaning treatments, eliminating various pollutions originating from previous forming operations (for example lubricant residues), and by coating operations, generally by organic matter, in order to resist subsequent physical or chemical attack, both from the content and from the external environment.
• a special feature of the manufacture of these boxes is that they are formed at a high rate, of the order of 2000 boxes / min, which implies that the cleaning and coating operations must be rapid, so as not to constitute a bottleneck. strangulation in their manufacture, whether the process is continuous (box by box) or discontinuous (by batches of boxes).
• the problem to be solved is therefore to find a method, a device and an apparatus for cleaning and coating of metal cans, making it possible to treat several geometries of cans either successively or simultaneously, thus avoiding the drawbacks or constraints stated above.
• auxiliary electrodes internal or external to the box body, electrically connectable to one of the poles of the current source.
• the device according to the invention can be used both in a device for batch processing of boxes and in a device for continuous processing on successive stations of the carousel type; moreover, it does not require neck shrinking and / or the formation of the collar, before treatment.
• operation c) is omitted.
• the cleaning or rinsing operations can be completed by admitting one or more gas streams into the cleaning or rinsing enclosure, increasing the turbulence of the bath and thus increasing the cleaning (or rinsing) efficiency.
• the apparatus in the case of the batch process of boxes, consists of several elements, comprising at least a cleaning station, a rinsing station, a coating station, a movable basket transportable from a station to the other and containing the bodies of boxes to be cleaned, rinsed or coated.
• the basket made of plasticized metal wire insulating material, has a perforated bottom and housings delimited by vertical frames, these housings being arranged in a regular manner, and covering the entire surface of the bottom of the basket.
• These housings generally have a straight prismatic shape with a polygonal base, preferably regular such as square or hexagonal, forming a network covering the entire bottom of the basket and lateral edges materialized by the reinforcements; their transverse dimensions are such that the circle corresponding to the largest of the diameters of the boxes to be treated is inscribed there.
• the side walls of these housings are delimited by vertical frames, covered with plastic.
• the basket is made of a material that is inert towards the cleaning, rinsing or coating fluids used.
• this (these) ring (s) will (ven) t guide during the upward movement of the box, while adapting to the various sizes of the boxes to be treated.
• the cleaning station essentially consists of a rectangular tank with a bottom and side walls, open at its upper part and a cover adapted to it.
• a rectangular tank with a bottom and side walls, open at its upper part and a cover adapted to it.
• the bottom of the tank there are arranged on the one hand through-injection nozzles, positioned substantially in the center of each of the corresponding housings of the basket and on the other hand electrodes.
• All of the nozzles are connected by suitable piping to a fluid reservoir (for cleaning, rinsing, or coating) either under load, or preferably by means of a pump; the overflow, delimited by a overflow, returns to the fluid reservoir after possible filtration or ultrafiltration.
• a fluid reservoir for cleaning, rinsing, or coating
• the tank also has a lower drain opening provided with a valve or tap.
• the tank is made of inert material with respect to the fluids used and preferably consists of a metal container coated with plastic.
• the nozzles are made of an electrically conductive material such as graphite or stainless steel.
• Electrodes On the bottom of the tank are also arranged vertical electrodes which are regularly arranged outside the basket housings. These electrodes can be provided with insulating sleeves making it possible to possibly reduce their active surface. They serve as auxiliary electrodes for a better homogeneity of the thickness of the electrophoretic coating and a better regularity of the external cleaning of the boxes. They also serve to guide the basket during its installation. In another variant, these electrodes may no longer be integral with the tank but with the basket itself: they will then be common to cleaning and coating operations.
• the cover comprises, in the vicinity of the center of each of the housings, an electric current supply constituted by a conductive piece, for example metallic (preferably stainless steel) for the coating, or aluminum for cleaning.
• a conductive piece for example metallic (preferably stainless steel) for the coating, or aluminum for cleaning.
• Their lower end can be mushroom-shaped (such as, for example, a 1 ⁇ 2 round head screw, placed upside down), which ensures contact with the bottom of the box being processed.
• All these current leads are connected to one of the poles of a current source, for example alternating in the case of cleaning, or continuous (anode) in the case of electrophoretic coating, with the breaking or setting devices. route required (switches). In the latter case, the direct current is preferably pulsed.
• the coating station is identical to the cleaning station described above, except as regards the nature of the fluid used.
• a basket consists of a metal frame 1 coated with plastic material forming a base and perforated side walls. It has 20x20 dwellings, with a square base ABCD. At each of the angles of these squares, there is a coated vertical frame. In each of these housings there is a metal box 2 placed upside down and resting on the frames 1 of the basket. The center of the housing 0 is substantially perpendicular to the axis 26 of the injection nozzle 24.
• the electrodes 3 are located in the center of the BEFG quadrilateral. Between the box body 2 and the frames 1 is placed a ring 6 of plastic material, which is fixed to the vertical frames by clipping or welding and whose inside diameter is slightly greater than the outside diameter of the box body 2.
• the cleaning section consists of a parallelepipedic tank comprising a bottom 21, and side walls, of plastic material, open at its upper part, capable of containing the basket described above and inert with respect to the fluids used.
• the bottom 21 is crossed by injection nozzles 23 consisting of a tube 24 and a base 25, located substantially on the axes 0 of the baskets; the tubes 24 enter the box body 2 through the opening 8.
• the bottom 21 is also crossed in a sealed and electrically insulated manner by the electrodes 3.
• These and the nozzles 23 are connected to a pole P of the current source (not shown).
• the electrodes enter the housings of the basket through the openings 9 thereof (fig. 1).
• These electrodes 3 also serve as elements for guiding the basket when it is placed in the treatment tank.
• each of the boxes being surrounded by 8 electrodes it is possible to modulate at will the distribution of the current lines around each of them.
• the electrodes 3 can be secured to the cover 10 or the basket (1) instead of being secured to the bottom of the tank 21.
• the tank also includes an overflow and a drainage tube.
• the coating tank has a constitution similar to the cleaning tank.
• the rinsing tank is also similar but does not have current leads 11 or electrodes 3.
• a cover 10 of insulating material comprising substantially on the axis 0 of the housing, a current supply 11 made of stainless steel (coating) or graphite (cleaning) having a cylindrical body 13 and held in place by a system of 'nut and locknut 14 and connected to the other pole P' of the current source (not shown).
• the height of the nozzles h A is 105 mm, and their diameter is 30 mm.
• the height under current supply h C is 130 mm
• the 400 box bodies are placed upside down in the basket containing 20 x 20 housings, which is brought to the cleaning station (fig. 4A).
• the nozzles 24 and the current leads 11 being connected to the terminals of an alternating current generator at a voltage of 15 volts.
• the electrolyte made up of a phosphoric acid solution whose electrical conductivity at 70-75 ° C is 70 mS / m is then admitted into the tank, by switching on the circulation pump, ensuring a flow rate of 2 m. 3 / h by nozzle.
• the box bodies are raised (see fig. 4B) and their bottom pressed against the heads of the current leads (12) and are purged of the air which they contain; the tank fills with electrolyte up to level 30 of the overflow fig.4; the electrolyte then completely immerses the can bodies in the high position.
• the electric current is then established for 2 to 5 s.
• the box bodies descend to the low position (fig. 4A).
• the tank is emptied by the evacuation provided for this purpose.
• the basket is removed and placed in the rinsing station where the box bodies are rinsed with water, obviously in the absence of electric current.
• the basket is then placed in the coating tank and the nozzles 23, the current leads 11 and possibly the electrodes 3 being connected to the terminals of a direct current source at a voltage of 100 to 380 volts, typically 200 volts.
• the electrophoresis bath consisting of anaphoretic epoxy varnish (at a rate of 10 g / liter, in water) whose pH is 7.7, the conductivity 1.76 mS / m and the temperature is allowed. maintained at 30 ° C, by the nozzles 23 and a cycle similar to that of cleaning is started.
• the anaphoretic treatment time is 2 to 15 sec, which makes it possible to deposit a layer with 1 to 10 ⁇ m of resin, under pulsed direct current (typically 50 ms under current + 20 ms without current).
• the rinsing is carried out under the same conditions as above.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Electroplating Methods And Accessories (AREA)
• Coating With Molten Metal (AREA)
• Forging (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9435340

Family Applications (1)

Country Status (9)

Families Citing this family (14)

Family Cites Families (10)

• 1992
  • 1992-11-03 FR FR9213437A patent/FR2697539B1/fr not_active Expired - Fee Related
• 1993
  • 1993-10-28 JP JP5270931A patent/JP2664861B2/ja not_active Expired - Lifetime
  • 1993-10-29 US US08/142,963 patent/US5435899A/en not_active Expired - Fee Related
  • 1993-11-01 KR KR1019930022977A patent/KR940011671A/ko not_active IP Right Cessation
  • 1993-11-02 DE DE69328280T patent/DE69328280T2/de not_active Expired - Fee Related
  • 1993-11-02 EP EP93420438A patent/EP0596817B1/fr not_active Expired - Lifetime
  • 1993-11-02 CN CN93119828A patent/CN1087958A/zh active Pending
  • 1993-11-02 CA CA002102248A patent/CA2102248C/fr not_active Expired - Fee Related
  • 1993-11-02 ES ES93420438T patent/ES2146605T3/es not_active Expired - Lifetime

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