Abstract: As for the high thickness ratio and small wall thickness and uneven structure characteristics of automotive air condition scroll, the scroll forming process is studied using back pressure forming process by the DEFORM software. The forming principle for backpressure deformation, the metal flowing rules and the force situation are analyzed, the material of scroll is 4032 aluminum alloy whose true stress-strain curve is obtained by high temperature compression test. Set 10 measuring points in the vortex, the effect laws of backpressure and backpressure distance on scroll forming quality are compared by simulation. Four factors and four levels orthogonal experiment is numerically simulated while billet temperature, mold temperature, backpressure and backpressure distance are independent variables, the data of the maximum forming load, height difference and flatness are acquired by the orthogonal experiment. The grey system theory was used in the parameters optimization of backpressure forming of scroll, the experiment is done on the self-designed molding machine, the results which meet the requirement of the scroll size and verify the feasibility of the forming process and the grey system theory.

Key words: backpressure, flatness, grey system theory, height difference, metal flow, scroll