Improved Synchronous Motion of Linear and Rotary Axes While Avoiding Torque Saturation Under a Constant Feed Speed Vector at the Endmilling Point – Investigation of Motion Error Under Numerical Control Commanded Motion –
Takamaru Suzuki*,, Kazuki Yoshikawa**, Toshiki Hirogaki**, Eiichi Aoyama**, and Takakazu Ikegami***
*Machine Systems Engineering Course, Department of Creative Engineering, National Institute of Technology, Kitakyushu College
5-20-1 Shii, Kokuraminami-ku, Kitakyushu, Fukuoka 802-0985, Japan
**Department of Mechanical Engineering and Science, Faculty of Science and Engineering, Doshisha University, Kyotanabe, Japan
***DMG MORI Co., Ltd., Yamatokoriyama, Japan
A five-axis machining center is known for its synchronous control capability, allowing complicated three-dimensional surfaces, such as propellers and hypoid gears, to be quickly created. Prior research has shown that it is necessary to improve not only the machined shape accuracy but also the machined surface roughness of free-form surfaces. Therefore, in this research, we aimed to maintain the feed speed vector at the endmilling point by controlling two linear axes and a rotary axis with a five-axis machining center to improve the machined surface quality. In previous research, we suggested reducing the shape error of machined workpieces (referred to as shape error in this research) by considering the differences in the servo characteristics of the three axes in the machining method. The shape error was significantly decreased by applying the proposed method, which uses a parameter (referred to as precedent control coefficient in this research) determined by calculation, rather than trial and error. Moreover, to maintain the feed speed vector at the endmilling point when machining complex shapes, a rapid velocity change in each axis is required, causing inaccuracy owing to torque saturation. The results of the experiments and simulations of previous research indicated that torque saturation can be evaluated via simulation. In this research, to reduce the shape error while avoiding torque saturation when movement has high angular velocity, we developed a theoretical method to obtain the most suitable precedent control coefficient of each axis by using a block diagram that considers torque saturation. Therefore, both shape error reduction and torque saturation avoidance can be realized by using the proposed method.
-  Y. Ihara, K. Tsuji, and T. Tajima, “Ball bar measurement of motion accuracy in simulating cone frustum cutting on multi-axis machine tools,” Int. J. Automation Technol., Vol.11, No.2, pp. 197-205, 2017.
-  T. Nishiguchi, S. Hasegawa, R. Sato, and K. Shirase, “Evaluation method for behavior of rotary axis around motion direction changing,” Int. J. Automation Technol., Vol.11, No.2, pp. 171-178, 2017.
-  A. Saito, M. Tsutsumi, S. Mikami, and S. Sisavath, “Development of calibration methods of 5-axis controlled machining centers (3rd report) – Measurement methods for various structural configurations of 5-axis controlled machining centers –,” J. of the Japan Society for Precision Engineering, Vol.69, No.6, pp. 809-814, 2003 (in Japanese).
-  J. F. Reintjes, “Numerical control: Making a new technology,” Oxford University Press, pp. 66-72, 1991.
-  E.-Y. Heo, D.-W. Kim, B.-H. Kim, D.-K. Jang, and F. F. Chen, “Efficient rough-cut plan for machining an impeller with a 5-axis NC machine,” Int. J. of Computer Integrated Manufacturing, Vol.21, No.8, pp. 971-983, 2008.
-  N. Natsume, K. Nakamoto, T. Ishida, and Y. Takeuchi, “Tool path generation for five-axis control semi finishing by use of square end mill,” Trans. of the Japan Society of Mechanical Engineers Series C, Vol.78, No.793, pp. 3305-3316, 2012 (in Japanese).
-  T. Ikegami, T. Hirogaki, and E. Aoyama, “Development of direct drive motor for machine tools and consideration of its performance in machining,” J. of the Japan Society for Abrasive Technology, Vol.60, No.6, pp. 333-337, 2016 (in Japanese).
-  R. Sato, Y. Terashima, and M. Tsutsumi, “Quadrant glitch compensator based on friction characteristics in microscopic region,” J. of the Japan Society for Precision Engineering, Vol.74, No.6, pp. 622-626, 2008 (in Japanese).
-  T. Higuchi, H. Kunisada, Y. Kunii, R. Sato, and M. Tsutsumi, “Compensation of quadrant glitches with two peaks in circular motions of machining centers,” Trans. of the Japan Society of Mechanical Engineers Series C, Vol.78, No.788, pp. 186-195, 2012 (in Japanese).
-  T. Hirogaki, “Effect of simultaneous control in constant direction of feed at cutting point to machined two-dimensional line-shapes,” Proc. of 2010 ISFA, JPL-2496, 2010.
-  T. Suzuki, Y. Maruyama, T. Hirogaki, and E. Aoyama, “Improvement of machining accuracy under constant feed speed at milling point with a five axis controlled machining center based on Advanced control Method,” Trans. of the JSME (in Japanese), Vol.83, No.849, 16-00518, 2017 (in Japanese).
-  R. Sato, Y. Yokobori, and M. Tsutsumi, “Dynamic synchronous accuracy of translational axes and rotational axes in 5-axis machining center,” J. of the Japan Society for Precision Engineering, Contributed Papers, Vol.72, No.1, pp. 73-78, 2006 (in Japanese).
-  T. Suzuki, K. Yoshikawa, T. Hirogaki, E. Aoyama, and T. Ikegami, “Improved method for synchronizing motion accuracy of linear and rotary axes under constant feed speed vector at end milling point – Investigation of motion error under NC-commanded motion –,” Int. J. Automation Technol., Vol.13, No.5, pp. 679-690, 2019.
-  Y. Ono, “Control of DD motor and its feature,” J. of the Robotics Society of Japan, Vol.7, No.3, pp. 254-259, 1989 (in Japanese).
-  Y. Iwashita, R. Tsuneki, S. Ikai, K. Iijima and N. Sonoda, “A method for determination of current control parameters avoiding voltage saturation and considering magnetic saturation for high precision drive of a permanent magnetic synchronous motor,” J. of the Japan Society for Precision Engineering, Vol.83, No.7, pp. 706-712, 2017 (in Japanese).
-  T. Hirogaki, Y. Nakamura, T. Horiuchi, E. Aoyama, and K. Ogawa, “Optimization of acceleration and deceleration processing suited to simultaneous control with five-axis machining center,” Proc. of 15th Int. Conf. on Advances in Materials & Processing Technologies (AMPT 2012), 26768, 2012.
-  J. Vivancos, C. J. Luis, J. A. Ortiz, and H. A. González, “Analysis of factors affecting the high-speed side milling of hardened die steels,” J. of Materials Processing Technology, Vols.162-163, pp. 696-701, 2005.
-  R. V. Fleisig and A. D. Spence, “A constant feed and reduced angular acceleration interpolation algorithm for multi-axis machining,” Computer-Aided Design, Vol.33, Issue 1, pp. 1-15, 2001.
-  T. Yamazaki, M. Seto, and M. Tsutsumi, “Design of acceleration and deceleration commands for NC machine tools,” J. of the Japan Society for Precision Engineering, Vol.66, No.8, pp. 1260-1264, 2000 (in Japanese).
-  Y. Kakino, Y. Ihara, Y. Nakatsu, M. Yonetani, and T. Teshima, “A study on the motion accuracy of NC machine tools (4th report) – Compensating for decreasing error of the circle radius during circular interpolation motion –,” J. of the Japan Society for Precision Engineering, Vol.54, No.6, pp. 1113-1118, 1988 (in Japanese).
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