臥式銑床主軸減振的模擬實驗研究外文翻譯
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- 外文翻譯Passive control has been effective in damping the machining vibration of thin-walled parts. However, physical addition onto the part causes the dynamics change and limits the engagement of cutting tool, especially in the application of multi-axis machining. Utilizing the non-contact eddy current damping, a two-degree-of-freedom apparatus is designed after experimental investigation into the magnet combination, magnetic flux density and magnetic flux mode on damping behaviors on a specifically designed platform. The apparatus is set up by mounting on the stationary spindle head of a five-axis CNC machine tool. The included neodymium magnets, and then the induced eddy current damping force are able to follow the feeding cutter through the control of two servo motors, keeping out of touch with the thin-walled part to be damped. As the damping force is able to resist the vibration of the machining point induced by the cutting force directly, it allows the design with less volume and mass (i.e. magnets and conductors). In the end, hammer tests are performed to verify the additional damping ratio imposed by the apparatus. Three-axis milling tests of a thin-walled frame are carried out to validate the damping of the apparatus, and five-axis milling tests of thin-walled blade type part are conducted to demonstrate its controllable damping and adaptability to complex tool path.
1. Introduction
Freeform thin-walled parts are quite common in aeronautic industries. Its machining has been a great challenge due to the conflict between low flexibility and high accuracy of desired geometry. A large number of publications have investigated the techniques to avoid ma-chining vibration, including cutting process optimization based on the stability lobes and structural dynamics modification by active or passive control [1].
Passive control technology is effective, low cost and easy to achieve; therefore, it has been widely used in the industry. Nakano et al. attached three dynamic absorbers to a collet chuck in order to suppress chatter in end milling operations [2]. Kolluru et al. presented a surface damping solution composed of thin flexible layer and distributed masses for large thin-walls [3]. Brecher et al. presented an analytic tuning method of multi-stage multi-mass damper that highly increases effective frequency range and robustness [4]. However, the disadvantage of a passive damper is that there is physical contact between the damper and the part to be damped, which causes the mass loading and added stiffness of the primary structure and limits the engagement of cutting tool especially in case of multi-axis machining....
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