Finite Element Analysis for the Put-In Force of Drawbar Mechanism in High Speed Air Spindle

[[abstract]]主軸高速化係工具機發展之重要趨勢，而在高轉速下，主軸各組件功能所受之影響為發展高速主軸必須探討之課題。 主軸拉刀機構係利用盤型彈簧提供適當的拉刀力，將刀具固定於主軸上，並確保在切削時發揮足夠的強度。拉刀機構之盤型彈簧，在高轉速產生之離心力使盤型彈簧變形，而減弱彈簧強度，拉刀力即因而受影響，失去原設定的拉刀效果，另外，刀把定位夾頭亦因高轉速之離心力影響，刀具挾持力亦降低，致使拉刀力需提升才能確保其拉刀效果。 本研究即針對轉速可高達12萬轉之氣浮高速主軸，利用〝ANSYS〞有限元素分析軟體，探討其拉刀機構，在高轉速下拉刀力之變化量，選以不同尺寸及不同疊合方式之盤型彈簧，配合不同斜錐角度之刀把定位夾頭作分析，了解氣浮主軸拉刀機構如何才能在高轉速下，維持一定之拉刀力，及在預設拉刀力的需求情況之下，盤型彈簧尺寸及疊合方式參考值，提供設計者作為設計氣浮高速主軸拉刀機構之參考。[[abstract]]Spindle tends to be high speed in the development of machine tools. With high rotational speed, the function of each part of the spindle could be changed. It is an important topic to investigate the influence of the function of each part in developing the spindle with high speed. Provided a suitable put-in force by the Belleville springs, the drawbar mechanism of spindle could fix the tools on the spindle. Due to the centrifugal force generated by the high speed rotation, the Belleville springs of the drawbar mechanism would be deformed and that would reduce the strength of the put-in force. On the other hand, the tool-holding force would also be decreased. Therefore, the Belleville springs of the drawbar mechanism have to be adjusted to keep the put-in force. In this study, the air spindle with the rotational speed over 120000 rpm is focused, the finite element analysis software 〝ANSYS〞 is utilized to investigate the variation of put-in force of the drawbar mechanism in high speed. Coordinating with different bevel angles of tool-holding device, different sizes and stack modes of the Belleville springs are selected to analyze how to keep the fixed put-in force of the drawbar mechanism under high rotational speed. Find out the sizes and stack modes of the Belleville springs with the presetting put-in force to provide the designer as a reference for designing the drawbar mechanism of the high speed air spindle