| Summary: | 碩士 === 國立高雄應用科技大學 === 機械工程系 === 105 === Preform is an intermediate shape between blanking and the final product. Preform design and optimization would affect the forming loads, material flow, tool wear and dimensional accuracy. Thus, the investigations of design and optimization of the preforming stage plays an important role in the metal forming process. The traditional topology optimization method is used in the field of structure design, in which little deformation is involved. However, the metal forming process behaves a large amount of plastic deformation, in which the mesh distortion occurs in the simulation process. Therefore, introducing the topology optimization into the metal forming process is a big challenge.
In this study, the analysis and simulation software are carried out by using the DEFORM-3D finite element software as well as CAD software and MATLAB software as auxiliary tools. The research procedures are separated into three steps. First, using the point tracking to design the preform, and check the volume loss and flow line after the simulation. The second part, type 1 (initial design) preform design is used to simulate the isothermal hot forging process for producing a disk with concentric shaft and eccentric shaft, and design the type 2 preform which is based on material filling condition and then conduct forging process simulation again. Finally, conduct the type 3 preform design which is based on material flow condition.
The simulation results show that the volume loss of the first simulation is 0.3904%, and the volume loss of the second simulation is 0.6433%, through the flow line and forging products are found surface defects on the eccentric shaft and concentric shaft. The simulation result of type 1 preform design depicts under filled condition at bottom of concentric shaft. The material volume is increased as preform design of type 2 to fix the under filled problem. In order to improve the condition of material flow distribution by increasing the material volume at eccentric shaft, as shown in the preform design type 3. The simulation result of the type 3 and the forged product are quite similar. In this research, the establishment of three dimensional background mesh and the points tracking data analysis are carried out by MATLAB software in order to perform the automatic preform design.
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