| Summary: | 碩士 === 國立高雄應用科技大學 === 模具系碩士在職專班 === 104 === In the sheet forming process, tool material needs to be rigid enough to sustain the impact of forming as well as flexible to prevent cracking during the process. If the tool surface hardness fails to support and resist during formation, sheet will spring back due to the lack of deforming force and stress. To avoid the tooling from insufficient rigidity while forming the sheet, high-speed steel and die steel are commonly used as tool materials. High-speed steel and die steel is able to provide sufficient mechanical strength support during sheet formation to achieve the best result in dimension as well as profile precision, also to eliminate issues such as springback, wrinkle and waviness. However, the leadtime for creating the tooling is usually too long to fulfill the trend of multiple designs and lead to less in production quantify, thus rapid tooling technology is introduced to shorten the leadtime and reduce the development cost.
In this study, electricforming of nickel layer is used to enhance the strength and surface hardness of aluminum epoxy so as to reduce the wear on the epoxy surface and increase the impact strength of it. Finite element method numerical model is first used to find the forming stress on the tool with different forming speed and with different thickness of nickel shell. Based on the simulation results, shell thickness and forming speed can be decided which is employed to manufacture the aluminum epoxy rapid tool with electricforming nickel shell for replacing the steel tool.
Study results show the thicker of the nickel shell and the slower of the forming speed, the lower aluminum epoxy strain value. Simulation results of 3 different shell thickness can all sustain during the forming process. Considering electroforming time and cost, 0.5mm shell thickness is selected with 300 mm/s forming speed. Experiments are carried for 300 cycles and no visible or measurable damage can be detected on the tooling surface which proves the electroforming nickel shell could provide enough rigidity during forming.
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