| 摘要 |
PURPOSE:To improve the rust inhibitive effect, etc., of coated films by subjecting the moldings of Al sheets to a chemical conversion treatment to form zinc phosphate films thereon and combining the moldings with steel sheet moldings and further, forming the zinc phosphate films on the surface of the assembly, then painting the assembly at the time of producing the combined members of the steel sheets and Al sheets of automobile bodies, etc. CONSTITUTION:An engine hood 11 and fender panel 12 of the automobile body 10 are formed by pressing 2 of the Al sheets A and the zinc phosphate films are formed on the surface in a 1st chemical conversion treatment stage 3. On the other hand, the steel sheets S are pressed 1 to form a body 13 and hood hinges 14. These Al sheet parts 11, 12 and the steel sheet parts 13, 14 are combined and coupled in an assembling stage 4 and thereafter, the zinc phosphate films are formed thereon in the 2nd chemical conversion treatment stage 5. The Al sheet parts are previously subjected to not the chromate treatment but the zinc phosphate pretreatment and, therefore, the degradation in the capacity of the treating liquid by elution of Cr acid is obviated and the deterioration in the adhesiveness of the coated films in the subsequent painting stage 6 is obviated. |
