Papers by Author: Zhong Yi Cai

Abstract: In order to manufacture a three dimensional sheet metal part effectively, a continuous sheet metal forming process (CSMF) based on flexible roll bending has been proposed and developed. This paper mainly focuses on the fundamental aspects of the process, the principle of CSMF is introduced and the method to estimate the downward displacement of upper roll based on the desired curvature of the deformed sheet metal is presented. The variation of the upper rolls downward displacement with the desired bend radius is shown in graphically. The smoothness of the CSMF parts was measured and analyzed. In the results, it is shown that a three-dimensional sheet metal part can be formed without defects and the formed surfaces are in good agreement with the target shapes.

Abstract: In this paper, an analytical solution for the three-roll bending process of thin-plate was presented. Based on the theoretical analysis on continuously loading and unloading deformation of the plate during roll-bending, the curvature equations governing the bending behavior of thin-plate were set up and then solved by integration. Combing the solutions with the geometrical relationships in three-roll bender, the deflection and bending angles occurring during the steady continuous bending period were obtained by an iterative scheme. Numerical examples were given to illustrate the application of the solutions. The variation of the top roll’s position with the intended bend radius, the curvature and deflection distributions on bent plate were shown in graphically and discussed.

Abstract: The deformation of sheet metal in the continuous flexible forming (CFF) process is complex and the formed result is affected by many factors. In this paper, the finite element model of CFF was founded and the forming processes of spherical parts were simulated with the software ABAQUS. The interaction between transversal deformation and longitudinal deformation in the CFF process is analyzed. Based on results of numerical simulation and forming tests, the process parameters of CFF is revised, and formed surface is measured by three dimensional sensing system, the measured results indicate the precision of formed parts are satisfactory.

Abstract: The software for the continuous flexible forming process was developed using Visual C++ platform. It can directly read the triangular mesh data of the CAD model. The three-dimensional model was reconstructed rapidly by using the core function of the OpenGL. Moreover, the mathematical model of adjusting the flexible rolls and the longitudinal curvature were established by this software. Using these mathematical descriptions the simulation of the continuous flexible forming process can be finished from the viewpoint of geometry.

Abstract: Three clamping devices of stretch forming machine were introduced, and the corresponding finite element models of the spherical parts were built by finite element software, the strain and thickness distribution of the forming parts were comparatively analyzed. The simulation results show that strain and thickness distribution of the forming parts with the multiple discrete gripper clamping mode are well-proportioned, its forming quality gets better than that with the whole flat gripper and adjustable curved gripper clamping modes. The experiment was performed and a typical spherical parts was formed with the multiple discrete gripper clamping mode. The experimental results are in good agreement with simulation results, which proves feasibility and practicability of the multiple discrete gripper clamping device of stretch forming machine.