Spring Back of Curved Flanges of Rubber Formed Aluminum Parts

Abstract:

Rubber forming is a common process for the fabrication of flanged metallic parts in the aerospace industry. The process enables cheap tooling, which is important since the product series are limited. In the process a rigid and a soft tool are combined to form a metal blank into the required shape. Most components made in this way are “flanged parts”, i.e. parts with a rather flat web plate and curved flanges at the periphery of the web plate. For flanged parts the determination of spring back of the flanges, straight or curved, is important, since the forming dies compensated with the spring back, will result in accurate products. Like all metal forming processes elastic and plastic deformations are combined in the same process cycle. The elastic deformations result in spring back and residual stresses, the ratio between these two depends on the shape of the product and the distribution of the plastic and elastic deformations. In this research aluminum alloys were used. The low Young’s modulus of these alloys results in rather high elastic responses upon deformation. Other aspects that have been evaluated are the effect of processing parameters like friction and distribution of strains. For stretch flanges the strain is distributed evenly along the flange, but not for shrink flanges, where buckling plays a role. Experimental research shows that the spring back of the flanges depend on a number of variables like the thickness, flange geometry, and material parameters. The spring back of a flange is also a mixture of different contributions: spring back due to the bending over the bend line, spring back due to the curvature of the flange, and spring back due to in-plane deformations. The research performed focused on the different components of the spring back and their interaction. Analysis of the data resulted in a new parameter by which a number of variables could be captured. This improves the understanding of the spring back phenomena and is a generalization of the results.

• Periodical: Key Engineering Materials (Volumes 554-557)
• Pages: 1851-1855
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.554-557.1851
• Online since: June 2013
• Authors: J. Sinke
• Keywords: Aluminium Alloy, Flanges, Soft Tools, Springback

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