Design and Application of Small Displacement Sensor to the Control of Blankholding Force in Deep Drawing/Stretching of Sheet Metal

• Main Authors: Jeng Guo-Ming, 鄭國銘
• Other Authors: Sy-Wei Lo
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/62275178105199026125

碩士 === 國立雲林科技大學 === 機械工程技術研究所 === 86 === Since most of the deep drawn/stretched sheet metal products are three-dimensional and non-axisymmetric, developing a new set of molds is usually a time-onsuming task. One of the main problems is how to control the plastic deformation of the sheet metal between the dies properly. Inappropriate plastic flow results in the instabilities such as the splitting or wrinkling. To avoid this, hydraulic cushions with adjustable blankholding force (BHF) based on stroke can be utilized. However, the success of such action relies on the designand application of the sensing system and the employed control criterion.The existing position or velocity sensors are generally too big to be implemented inside the mold to measure the velocities of the workpiece on the desired spots. The control criterion or the BHF-stroke curve is pre-determined eit her by FEM simulations or by a series of experiments with selected BHF values.Due to the unrealistic friction model, the result of the FEM simulation is not warranted. On the other hand, conducting many tests with assigned BHF during punching is costly and time-consuming. It is also lack of flexibility and the optimum BHF-stroke curve can hardly be obtained. In the proposed thesis, at first, an affordable mini-velocity sensor whichcan be easily concealed in the mold will be developed. It is small enough tomeasure the workpiece velocity on the shoulder corner of the die. Many sensorscan be arranged in different positions in the flange area. A drawing die set withhydraulic servo-controlled BHF, which was constructed during the project "DeepDrawing Die with Hydraulic Servo-controlled Blankholding Force" under the supportof NSC, will be equipped with the new sensors to evolve a real-time, multi-inputcontrol criterion.