Effect of Process Parameters on Thin-wall Products under High-frequency Vibrating Tools, Case Study: Ultrasonic Assisted Deep Drawing Process

Ultrasonic Assisted Deep Drawing (UADD) is a state of the art Conventional Deep Drawing (CDD) process that results in improved formability and decrease in forming force. In this novel technology, the forming tool fluctuates under low amplitude and high frequency which is supplied by an ultrasonic package including generator and transducer. The main objective of this research is study of various parameters affecting the deformation behavior of the formed thin cylindrical-parts by UADD process, based on experimental tests and numerical methods followed by statistical approach. In this regard, a sophisticated Finite Element Model (FEM) including surface effect and stress superposition is developed. Nevertheless, a robust technological equipment is designed and fabricated in which the special die as a main vibratory tool can be longitudinally stimulated by enforced vibrations with frequency very close to the 20kHz. Consequently, experiments are performed to determine the effectiveness of the ultrasonic vibration, as well as, calibrate the established FE model. The simulation outputs and the relevant experimental tests are compared based on the forming force and drawing depth results, and an acceptable agreement is achieved. Based on the validated numerical model, Design of Experiment (DOE) by Response Surface Methodology (RSM) is utilized to run multiple simulations. Moreover, the effect of six parameters in the UADD process on the maximum forming force and the minimum thickness of the formed cup is statistically evaluated and high-reliability regression models based on the analysis of variance (ANOVA) with 90 simulations are generated to estimate these two output parameters. As a result, ultrasonic vibration amplitude, punch nose radius, and blank diameter with 37.22, 21.68, and 19.03% of contribution, respectively, were the most effective parameters on the required forming load. Furthermore, the results illustrated that ultrasonic vibration amplitude was the most important parameter on thickness reduction of sheet with 69.92% contribution.