- 學位論文
工具磨床鞍座模態分析與優化
Improvement of Saddle of Tool Grinding Machine Based on Modal Analysis
摘要
磨削技術廣泛用於機械工業，砂輪轉速高且材料移除量小是磨削工法的特點，工具磨床採用磨削原理成型各類型刀具由來已久。近年隨著切削條件的嚴苛考驗，刀具研磨精度要求也隨之提高，面對砂輪線速度的提升，工具磨床結構動剛性特別重要。良好的結構動剛性來自於設計階段對於結構靜剛性的優化。傳統採用增加機台質量以獲取高剛性的結構設計理念已經不敷工具磨床的需求，再者，整機高重量的成本亦無法面對市場成本的競爭。基於上述需求考量，工具磨床的結構優化有其必要。 本研究主要探討電腦數值控制工具磨床鞍座結構靜剛性特性表現，鞍座結構下接底座、上接工作台；在承受巨大磨削力的情況下結構變形量需低於0.01mm。研究採用有限元素法作為結構模態分析理論，搭配實驗模態的擷取進行比對，以驗證鞍座各階的自然頻率與振型。後續進行結構輕量化與自然頻率提升。研究結果顯示透過支撐肋的再設計，鞍座可有效減重5.87％且最大變形量0.008mm。若進一步對頻率進行優化設計，鞍座在增加結構重量3.47％的條件下，可維持最大變形量0.008mm、第一階自然頻率則由196.14Hz提高到215.26Hz，增加幅度9.74％。
並列摘要
Grinding technology is widely used in the machinery industry. The characteristics of grinding are that the speed of grinding wheels is high and the amount of material to be removed is small. Tool grinding machines, which are based on the principle of grinding, are used to form various types of tools, and they have a long history. In recent years, with rigorous tests of cutting conditions, the requirement of tool grinding accuracy has increased. To response of the wheel speed of the upgrade, the dynamic rigidity of a tool grinder structure is particularly important. Good structural rigidity results from its optimization during the design phase. The design theory of conventional methods, in which the weight of a machine is increased to increase structural rigidity, is inadequate for tool grinding machine requirements. Furthermore, the high cost of such machines cannot compete with market costs. Based on the above considerations, it is necessary to optimize the structure of tool grinding machines. This research primarily focuses on the static characteristics of the saddle structure of a computer numerical control tool grinding machine. The saddle structure is connected to a base and a table. The deformation of the structure is less than 0.01 mm under the condition of large grinding force. The finite element method is used for structural modal analysis, and experimental modal analysis is used to compare the natural and modal frequencies of the saddles. Then, a lightweight structure is created and natural frequency is enhanced. The results show that the weight of a saddle can be effectively reduced by 5.87%, and its maximum deformation is 0.008 mm. If frequency is optimized, the saddle can maintain a maximum deformation of 0.008 mm when structural weight is increased by 3.47%. The first order natural frequency is increased from 196.14 Hz to 215.26 Hz; the rate of increase is 9.74%.