DE4101957C2 - Surface treatment processes - Google Patents

Description

The invention is directed to a method for the treatment of surfaces using a Fluidized bed of the type specified in claim 1.

Such a treatment is from DE-A-32 30 513 known. The known fluidized bed has a fluidized bed dium, a mixture containing graphite, from inorganic materials such as lime and lime oxide, and an organic material of highly saturated fatty acid ren, especially stearate salts with the purpose of the Ein dragging bed particles with sanding the surface in the subsequent workplace. The known fluidized bed is used in particular for heating Workpieces.

Something arises when cleaning metal surfaces other problems with different cleaning procedures are known in which alkaline, acidic and aromatic Solvents are used, and electrolytic, me chanic abrasive and thermal processes application Find. Often, these processes raise large environmental and Disposal problems, e.g. B. the elimination of the used Solvent.  

Especially for sensitive, high-gloss metal surfaces surfaces become degreasing or deep stain free drying after polishing or galvanic Vere use diving or steam baths that damage the environment Liche and carcinogenic perchlorethylene as a solution medium included. According to the latest regulations, such are Plants are only available for operation to a limited extent to let.

The object of the invention is to provide a solution with for treatment, especially for cleaning surfaces Chen, the use of environmentally compatible substances possible becomes.

This object is characterized by the invention resolved characteristics of the main claim.

At this point it should be noted that treatment of Me tallteile in fluidized bed reactors known per se is (e.g. DE-24 00 284-A, DE-30 06 754-A1, DE-36 23 890-A1, DE-37 34 169-A1, GB-PS 1 569 152), which is in the known fluidized beds around single-component fluidized beds delt.  

With the procedure according to the invention is used The organic granules achieve this as scouring can act on the surface as they ver are equally porous. The dirt particles, fat particles and water droplets are removed from the one to be treated Removed surface and from these granulate particles taken. The proportion of inorganic granules made of glass and / or ceramic materials prevents a too high Solids discharge of the natural granules at the gas outlet of the Fluidized bed reactor.

Especially when inorganic granules with a smaller volume compared to the organic granules particles are used, a fluidizing, the fluidized bed cover layer. It has shown that in particular glass both for water absorption can also be used for high-gloss polishing.

In a further embodiment, the invention provides for the present invention hen that alumina is used as the ceramic material which is particularly distinguished by its roughening we distinction.

A component of the Bulk fed and electrostatic charge preventive additive, especially an organic acid,  ensures that there are no granulate particles on the inside walls of the reaction chamber of the fluidized bed reactor or the surface to be treated due to electrostatic Establish attraction. To ensure environmental friendliness here too To ensure the procedure, vinegar or Zi tronic acid added to the bed.

Another advantage is that as a gas for the by the we Bedbed plants led gas flow depending on the to be treated Surface of an inert gas or an inert gas is used. For highly sensitive surfaces, if possible, only Noble gases are used, for example, to make a new one Avoid surface oxidation.

According to the invention, different granulate mixtures are used for a wide variety of cleaning purposes:
For spot-free drying of galvanically high-gloss workpieces, it has been shown that a mixture of granules of wood, glass balls and an acid is used as an additional component in an advantageous manner.

For cleaning printed circuit boards, especially sweat fingerprints as preparation for soldering will mixture described in the last section Alumina added.  

Degreasing of surfaces is done in particular by a Mixture of corncob meal, glass balls and acid.

The measurement gives information about the procedure, which then depends on the desired treatment can be regulated accordingly; for example as the temperature increases, the gas pressure lowers etc. The conductivity monitoring is also very important to measure the amount of citric and / or acetic acid vote, which is to be added to the filling in order to electrostatic attraction between the surfaces and the To minimize granulate particles.

The invention is based on a figure of a We bed system for example explained in more detail.

The fluidized bed system shown in a highly simplified manner is generally designated 1 . It has a reaction chamber 2 , a cyclone 3 , a side channel blower 4 , a control unit 5 and four return channels 6 and a lock 10 .

In the reaction chamber 2 of the fluidized bed reactor 1 there is, as an example, a lampshade 7 to be treated, the outer surface of which is to be polished to a high gloss. As indicated in a viewing window 8 , the bed 8 should be in the so-called "flow state". The individual NEN granules 9 , the organic granules Chen with 9 a and the inorganic granules with 9 b, form the two-fluid bed in the reaction chamber 2 and bounce on the surface of the lampshade 7 to be treated.

For the sake of simplicity, the various measuring and control devices 11 and further details of the eddy current reactor are not shown in detail in the figure.

The method for treating the surface is explained in more detail below:
If a gas stream flows through the bed of organic granules 9 a and inorganic granules 9 b, the pressure loss of the gas rises over the height of the bed with increasing gas velocity until the bed suddenly loosens at the so-called loosening point and changes to the "fluid bed state"" transforms. In this "fluidized bed", the movement of the individual granulate particles is so violent that when an organic granulate particle impacts the lampshade 7 , the rough and porous surface of this particle removes dirt particles and fat particles from the surface of the lampshade 7 to be treated.

When an inorganic granule 9 b strikes, the water droplets are removed and the surface is polished. Characterized in that the inorganic granules 9 b have a smaller volume but a greater density than the organic granules rule, an upper layer of inorganic granules 9 b forms as a covering de fluidizing layer. This prevents the natural granulate 9 a from being too high at the gas outlet of the fluidized bed reactor.

Claims (5)

1. A method for treating surfaces, in particular for cleaning surfaces, using a fluidized bed with a bed of at least two different components with at least one organic and one with organic granules, characterized in that a granulate made of natural blast and / or Beech wood and / or cherry heartwood and / or walnut shells and / or peach kernels and / or corn cobs and that a granulate made of glass and / or ceramic materials is used as inorganic granules. 2. The method according to claim 1, characterized, that aluminum oxide is used as the ceramic material. 3. The method according to claim 1 or 2, characterized, that the inorganic granules with a smaller Volume compared to the organic granules to form a fluidizing, the fluidized bed be bordering cover layer can be used.   4. The method according to any one of the preceding claims, characterized, that as an additional component of the bed the elektrosta table-preventing additive, especially vinegar and / or Citric acid is added. 5. The method according to any one of the preceding claims, characterized, that as gas for that passed through the fluidized bed reactor Gas stream an inert or an inert gas is used.