閉機構鏈工具機研究與開發

Development of a CNC Machine Tool with Closed Kinematic Chain

薛淳方

指導教授 ： 雷衛台

國立清華大學/工學院/動力機械工程學系/碩士(2013年)

摘要

本論文針對Hexapod構型之六維運動量測裝置研發新型的可伸縮雙球量測桿，此量測桿使用面接觸雙滑動對，為對稱設計，降低量測桿因重心偏移而自旋之可能，另外，此量測桿使用殷鋼光學尺，使量測桿有極佳的熱穩定性，此二設計改進方法提升了六維運動量測裝置的量測精確度。本論文另外提出於單一參考座標系加工之概念，將六維運動量測裝置整合於三軸工具機上，以並聯機構之構型的六維運動量測裝置將開放機構鏈兩末端的主軸端與工件端閉合，構成直接回授之閉機構鏈工具機，並以六維運動量測裝置即時量測室溫對刀具位置的影響，以及主軸高速運轉生熱後對於刀具和工件間位置的影響，以實驗驗證此研發之六維運動量測裝置的量測精度，最後實現以此六維運動量測裝置為直接回授之閉機構鏈工具機，以六維運動量測裝置之量測結果做即時位置控制。由於刀具相對工件之直接位置回授，此創新研發之閉機構鏈工具機之加工精度不會受機器幾何誤差、室溫變化、主軸及其他熱源影響，此特性以工件之實際加工測試結果成功驗證

關鍵字

並聯機構 ； 量測裝置 ； 閉機構鏈

並列摘要

A new type of telescopic double ball bar is presented in this thesis for the Hexapod type six-DOFs motion measurement device (MMD). This double ball bar has a symmetrical geometry design to avoid the effect of self-rotation due to the mass center offset. Besides, this double ball bar uses low thermal expansion material INVAR for the linear scale so that it is non-sensitive to temperature variation. These two design improvements greatly increase the precision of the MMD. In addition to the design of the new double ball bar, this thesis also presents a new concept of machining in a single reference coordinate system, which uses the MMD to close the serial kinematic chain between the tool and the work piece. The MMD, serving as a direct measurement device, can measure the relative position and orientation between the cutting tool and the work piece in real-time. Variations caused by the changing room temperature or the internal heat sources of the machine tool such as the main spindle and motors can be measured by the MMD. The MMD is used to close the serial kinematic chain and serves as direct feedback device for the real-time position control of the machine tool. Because the relationship between the cutting tool and the work piece is measured directly, the machine tool will not be influenced by its geometric and thermal errors resulted from changing room temperature, main spindle or other heat sources. This feature is testified by real cutting tests of work pieces

參考文獻

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