Dynamic characteristics of NC table with SVD

Abstract

This paper employs the SVD (singular value decomposition) method to study dynamic characteristics of a numerical control (NC) table. Acceleration signals of the NC table at three directions are tested; the singular spectrum of the signals is acquired with SVD; principal components of the signals are found out; dynamic characteristics of the signals and their contributing factors are studied by extracting dynamic characteristics of principal components; and signals and principal components are quantitatively analyzed by calculating signal energy. Results indicate that signal characteristics of the previous two principal components are apparent, based on which dynamic characteristics of chaotic signal can be extracted. Signal at the perpendicular direction of the table is significantly correlated with that at the horizontal motion direction, which indicates that they are excited from the same vibration source. However, signals perpendicular to each other in terms of the motion direction at the horizontal level are rarely correlated; the total signal energy is maximum at the motion direction, minimum at the horizontal non-motion direction, and medium at the perpendicular non-motion direction. Bending vibration of the lead screw at the perpendicular direction is far more violent than that at the horizontal direction.

References

1. Koren Y . Designof a digital loop for numerical control. In: : Pure of the International Conference on Ind Elec and Cent Inst, 1978 : 212–217
2. Weck M . HandBook of Machine Tool. New York: Wiley, 1984
3. Kao J Y, Yeh Z M, Tarng Y S, et al.. A study of backlash on the motion accuracy ofCNC lathes. Int J Mach Tools Manufact, 1996, 36(5): 539–550. doi:10.1016/0890-6955(95)00064-X
4. Lauderbaugh L K, Ulsoy A G . Dynamic modeling for controlof milling process. ASME Journal for Industry, 1988 : 367–375
5. Kulkarni P K, Simivasan K . Identification of discretetime dynamic models for machine tool feed drives. Modeling of Machine Tools, ASME Pub, 1991 : 1–20
6. Chen Y, Tlusty J . Effect of low-friction guidewaysand lead-screw flexibility on dynamics of high-speed machines. Annals of the CIRP, 1995, 44(1): 353–356
7. Ebrahimi M, Whaley R . Analysis, modeling and simulationof stiffness in machine tool drives. Computerand Industrial Engineering, 2000 : 93–105
8. Zhao Yanjiang, Wang Shuxin, Liu Youwu . A study of optimized simulation of servo feed systemof machining centre. Journal of Hebei Universityof Science and Technology, 1996 (2): 32–37 (in Chinese)
9. Xu Chuangwen, Mu Xiqing . Analysis on effect of feedservo system characteristics on processing precision. Aviation Precision Manufacturing Technology 2002, 38(5): 43–46 (in Chinese)
10. Wu Nanxing . A study of simulation technology and structural dynamic featuresof CNC lathe with high speed and high precision. Doctoral Dissertation of Southeast University, 2004 (in Chinese)
11. Wu Yalan . Development and study on CNC lathe feed system and hydraulic servotool rest. Dissertation for the MasterDegree of Shandong University, 2002 (inChinese)
12. Duan Lixiang, Zhang Laibin, Wang Zhaohui, et al.. De-noising of diesel vibration signal usingwavelet packet and singular value decomposition. Journal of China University of Petroleum (Edition of Natural Science), 2006, 30(1): 93–97 (in Chinese)
13. FECIT Sci-Tech ProductR&D Center. . MATLAB7 Technology and Application of Auxiliary SignalTreatment. Beijing: Publishing House of Electronics Industry, 2005 (in Chinese)