NL297276A - - Google Patents

Abstract

<PICT:1056846/C6-C7/1> Aluminium workpieces are anodized by containing the workpieces in a rotatable rack of drum form, which can be raised and lowered in a series of locations including pre- and postanodizing baths where one or more liquids are sprayed on to the articles. Pre-anodising treatments specified include alkali cleaning, wash, acid etch, wash, and post-treatments include sealing with hot water or nickel acetate solution, dyeing, steaming, and drying with hot air. Preferably four baths are used for pre-treatment, anodizing, and two post-treatment baths used altenately, this treatment taking less time than anodizing. Fig. 2 illustrates one stage in which the rotatable rack 90 with associated gear 7 and motor 83 is mounted within a tank casing 70, which can be lifted out of and inserted in a container 1, having a sloping base 10 leading to an outlet 10. After inserting the unit, the top member is secured to the main frame member 67, and a lid 95 is provided to prevent escape of vapours. The rack comprises an axis 74 (driven by motor 83 and belt 88) on which is mounted spider members 88, 89 to which the parts to be treated are secured, e.g. long lengths of aluminium building sections 91. Liquids and steam are admitted in the succeeding stages through jets 21. These are absent in the anodizing bath. The liquids escape at the bottom and drain into individual gutters 31, for recirculation or rejection as necessary. When a liquid treatment stage is completed, the rack may be tilted to assist draining. The rack is rotated at 2 to 6 revs per minute. The normal anodizing, etching, and cleaning agents are specified.