Determinação experimental do fator K para o desenvolvimento do blank no processo de dobra a ar com matriz em V de chapas de aço carbono: um estudo de caso

Abstract

This undergraduate thesis presents an applied study on the experimental determination of the K-factor in V-die air bending, aimed at blank development for manufacturing carbon-steel parts. The research was conducted in an industrial environment at a metalworking company located in the Manaus Industrial Pole (Brazil), using test specimens produced under controlled conditions for sheet thicknesses of 0.90 mm, 1.20 mm, and 1.50 mm. The methodology integrates a standardized reverse-engineering workflow in sheet-metal bending, with measurement traceability and defined data-processing rules, in order to reduce reliance on empirical adjustments during press-brake setup. The K-factor was determined through algebraic rearrangement of geometric relationships, isolating K from bend allowance (BA), external dimensional measurements, and flat-pattern length, enabling consistent determination of bend deduction (BD) and outside setback (OSSB) for CAD/CAM parameterization. As a result, thickness-specific experimentally determined values of K were consolidated, yielding K = 0.455 (thickness 0.90 mm), K = 0.421 (thickness 1.20 mm), and K = 0.454 (thickness 1.50 mm), with associated mean inner radii of R = 1.20 mm, 1.32 mm, and 1.42 mm, respectively. Practical application of these parameters to validation parts demonstrated agreement between the CAD flat pattern and the process behavior, achieving 96.4% dimensional compliance according to the general tolerances of ABNT NBR ISO 2768-1:2001, tolerance class m, with a single marginal nonconformity. It is concluded that the proposed method increases accuracy, repeatability, and traceability in blank development and in the standardization of industrial sheet-metal bending.