Installation for the cataphoretic dip coating of articles
An installation for the cataphoretic dip coating of articles, in particular of vehicle bodies, comprises in known manner a dip tank, into which the articles can be immersed. The negative terminal of a coating voltage source can be connected with the immersed articles; the positive terminal of the voltage source is connected with at least one anode immersed in the coating liquid present in the dip tank. This anode has a cross-sectional profile which, in at least one portion, is adapted as a curved surface to the outline of the articles to be treated in such a manner that the anode follows the outline of said article in approximately parallel manner. This is made possible by the electrodialysis apparatus, by means of which the acid formed during the coating operation is removed from the coating liquid and which is necessary for such installations, being arranged outside the dip tank.
1. An installation for the cataphoretic dip coating of articles, the installation comprising
a) a dip tank, which is partially filled with a coating liquid, into which the articles can be immersed;
b) a coating voltage source, to the negative terminal of which the immersed articles can be connected and the positive terminal of which is connected with at least one anode immersed in the coating liquid present in the dip tank;
c) an electrodialysis apparatus, which is arranged outside the dip tank and by means of which the acid formed during the coating operation can be removed from the coating liquid, such that the acid content in the coating liquid remains within an admissible range, wherein
d) the anode has a cross-sectional profile which, in at least one portion, is adapted as a curved surface to the outline of the articles to be treated in such a manner that the anode follows the outline of said articles in approximately parallel manner, and further wherein the anode has a U-shaped profile with two lateral portions and a lower portion, which joins the lateral portions together, wherein at least one of the lateral portions and/or the lower portion of the anode has a curved surface.
2. The installation according to claim 1 , wherein the lateral portions of the anode are concavely curved when viewed from the articles.
3. The installation according to claim 1 , wherein at least in its upper part, the anode consists of sheet metal.
4. The installation according to claim 1 , wherein at least in its lower part, the anode consists of a material permeable to the coating liquid.
5. The installation according to claim 4 , wherein the material permeable to the coating liquid is formed from a wire mesh or screen netting, a grating or a plurality of mutually spaced rods.
6. The installation according to claim 1 , the anode consists at least in part of iridium-coated titanium.
7. The installation according to claim 1 , wherein the articles include a vehicle body.