Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns

Definitions

• the invention relates to methods for coating a Surface with a release agent.
• soot is used to separate the press disk and Al block for use; the soot is burned an acetylene flame on an end face of the Al block deposited. This process must be carried out with every new Al block be repeated.
• Oils are usually used to coat the press shears used, which evaporate on contact with the hot A1 and thereby achieve a separating effect.
• pigment-free recipes are used, which are based on water or mineral oils with additives.
• pigment-containing formulations of release agents are also used.
• the pigments used comprise a whole range of solids such as graphite, MoS 2 , BN or talc.
• soot as a special case is common to all previously known release agents that they in the form of liquid suspensions or emulsions must be applied. They are usually commissioned by spraying on the warm to very hot surfaces. at at high temperatures there is a risk of ignition volatile components or existing solvents or the loss of the active ingredient when suddenly evaporating in the Contact with the hot surface. In addition, the Evaporation products pose a significant burden to the Ambient air created by the formation of Decomposition products is still increased. Usually arrive a large part of the components in the water cycle, which in the Area of equipment is installed and must be at this point are elaborately eliminated.
• the object is achieved by a method which thereby is characterized in that a BN powder by means of electrostatic Coating is applied to the surface.
• the surface to be coated can e.g. to the Surface of the molding tool, e.g. the press washer or the baling shear act. In principle, however, it is also possible the surface of the non-ferrous metal with the ram is contacted. Since the means separation layer applied in the process according to the invention has good surface adhesion, the one with the Nonferrous metal surfaces coming into contact with the shaping press tool treated as this treatment must be repeated after 3 press cycles at the earliest.
• BN powders are equally good for Coating are suitable. Some powders include to a high consumption, an irregular coating of the Surface, and clogging of the nozzle of the Applicator.
• An irregular coating can lead to an uncontrollable Sticking or sticking the non-ferrous metal to the Contact point of the non-ferrous metal with the metallic Lead material.
• BN powders are used which have a fineness corresponding to a specific surface of 10-50 m 2 / g.
• the BN powders particularly preferably have a specific surface area of 10-30 m 2 / g, in particular a specific surface area of 10-20 m 2 / g.
• the powder also contains boric acid and boron oxides as B203 below 5 W, particularly preferably below 0.5%.
• the content of the various boric acids such as, for example, meta- or ortho-boric acid and of boron oxides, as is customary in the prior art, is stated as B 2 O 3 content after their analysis.
• the moisture content of the powder is given as an H 2 O content of less than 1%, particularly preferably less than 0.2%.
• the BN powder is fluidized in a storage container with a fluidizing gas.
• the fluidizing gas is usually compressed air.
• Other inert gases such as N 2 , noble gases or gas mixtures can also be used.
• the fluidized BN powder is charged electrostatically. This happens, for example, as usual for powder coatings, in a commercial paint spraying device for powder coatings.
• the BN particles are preferably charged with a Voltage of 75 - 80 kV worked.
• the fluidized BN powder is loaded onto the Sprayed on and coated the surface evenly provided parts. This is done in the same way as usual Powder coating.
• the throughput of BN powder is preferably adjusted to the values suitable for coating by the conveying gas pressure and the nozzle geometry (especially the nozzle diameter).
• the conveying air is therefore preferably used at 0.5 - 1.5 bar, the fluidizing air at 0.3 - 0.8 bar.
• the total air volume is about 5 - 8 m 3 / hour.
• Handling can either be done manually - but it is a fully automated implementation of the method without further ado possible.
• tension and the pressure regulate the order quantity and liability.
• the invention thus also relates to the use of BN powders as a release agent in the shaping of non-ferrous metals as well a release agent consisting of BN powder.
• a release agent consisting of BN powder.
• BN powder Preferably acts it is the BN powder mentioned as preferred.
• Coating is more durable than the conventional one Release coating. It enables multiple Repetition of the extrusion cycle before a new job is required.
• the coating method according to the invention has proven to be extremely simple, quick and convenient to carry out exposed.
• Powders suitable for use in the process according to the invention are on the market in a wide range of properties available.
• a BN powder preferably for the Use in the method according to the invention is also suitable made from commercially available hexagonal BN powder.
• the B 2 O 3 content of the powder is reduced by washing z. B. with water or alcohols to the desired value.
• Moisture levels that are too high are dried, e.g. in usual drying cabinets may with protective gas or Vacuum drying reduced to that for the invention Powder to achieve necessary values.
• the bulk density of the BN powder required according to the invention becomes if necessary, by grinding the possibly pretreated BN powder set. It is preferable to ensure that no excessive moisture absorption during grinding he follows.
• a number of conventional "dry” grinders come as Processes such as by means of pin mills, rotor mills, Ball mills in various designs are used.
• the simple application of the BN powder was confirmed in tests and the outstanding separation effect of BN compared to Al.
• the use of the powders is not limited to Al; the application of BN powder according to the invention by means of electrostatic coating without any binders and free of other substances such as solvents is also for those Processing of a whole range of other non-ferrous metals such as B. Cu, Zn, Mg, Pb, Sn or their alloys are suitable.
• the invention therefore also relates to the use of the Process according to the invention for coating surfaces extrusion of non-ferrous metals.
• the non-ferrous metals are preferably Cu, Zn, Mg, Pb, Sn and their alloys.
• BET surface area of 14.5 m 2 / g, a B 2 O 3 content of 0.12%, a moisture content of 0.25% H 2 O and a bulk density of 0.55 g / cm 3 (powder I) was ground in a pin mill with a throughput of 20 kg / hour.
• the powder thus obtained (Powder II) had a spec.
• Powder II was electrostatically coated (Fa. According to) (80 kV; 0.8 bar conveying air on the inlet side, 0.4 bar fluidizing air, 5 m 3 / hour air volume for conveying) is applied to a press disk with a diameter of 20 cm. The powder immediately settled evenly on the press disk. Approx. 0.5 g BN powder are used. A new coating was only necessary after a further three extrusion cycles.
• a hexagonal BN powder with a fineness corresponding to a specific surface area of 6 m 2 / g and a B 2 O 3 content of 9% (powder III) with a bulk density of 0.6 g / cm 3 was ground in a ball mill a specific surface area of 15m 2 / g was reached.
• the powder IV thus obtained was dispersed several times with water and washed out until the B 2 O 3 content was reduced to 0.1%. Finally, the powder was dried in vacuo at 60 ° C. to a residual moisture of 0.2% and ground in a rotor mill to destroy the agglomerates.
• the consumption corresponded to the value from Example 1.
• the coating was uniform and allowed pressure disks that came into contact with the layer to be used three times before renewed coating to form Al.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Extrusion Of Metal (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

Country Status (10)

Families Citing this family (14)

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• 1998
  • 1998-09-17 DE DE19842660A patent/DE19842660A1/de not_active Ceased
• 1999
  • 1999-09-14 TW TW088115877A patent/TW475909B/zh not_active IP Right Cessation
  • 1999-09-16 WO PCT/EP1999/006850 patent/WO2000016931A1/de active IP Right Grant
  • 1999-09-16 JP JP2000573878A patent/JP2002526265A/ja active Pending
  • 1999-09-16 PL PL99347358A patent/PL347358A1/xx unknown
  • 1999-09-16 ES ES99969361T patent/ES2179700T3/es not_active Expired - Lifetime
  • 1999-09-16 BR BR9913865-4A patent/BR9913865A/pt not_active Application Discontinuation
  • 1999-09-16 DE DE59901823T patent/DE59901823D1/de not_active Expired - Fee Related
  • 1999-09-16 CA CA002345922A patent/CA2345922A1/en not_active Abandoned
  • 1999-09-16 CN CN99811074A patent/CN1318000A/zh active Pending
  • 1999-09-16 EP EP99969361A patent/EP1115520B1/de not_active Expired - Lifetime

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