Effect of Inclined Angle in Trimming of Ultra-high Strength Steel Sheets Having Inclined and Curved Shapes

Trimming the scrap portion of ultra-high strength steel (UHSS) components poses a significant challenge due to the inherent high strength and hardness characteristics of the material. For UHSS components with a higher geometric complexity such consisting of inclined and curved sections, sharp tilt, and small bend radius, the large trimming load results in poor sheared quality and shape defects, which commonly happen in these areas. This research investigated the effects of applying a small inclination angle to the punch in the trimming of the UHSS parts having an inclined and curved shape. The inclined punch was modified to four sets of different degrees of inclination i.e., 1°, 3°, 5°, and 10°. A comparative analysis of the trimming load, trimming energy, sheared edge quality and shape defects was conducted between these modified punches and the normal punch for their effectiveness in the trimming operation. Results showed that the application of inclination angle significantly decreased the trimming load, reduced the trimming energy, and improved the sheared edge surface quality, as well as prevented the shape defects at the inclined and curved zones as compared to the outcomes produced when trimming using the normal punch. The study suggested that the change to the punch geometry is an effective option to improve the performance of the process as well as the quality of the part, particularly in trimming the high-strength components having complex shapes.