Empirical Power Consumption Model for Rotational Axes in Machine Tools

A machine-based power consumption model was developed to cope with a wide variety of machine tool configurations. By focusing on machine components, power consumption can be measured readily and reconfigured per individual component. This research focused mainly on feed drive units of machine tools, and particularly the power characteristics of rotational axes. Although numerous studies have investigated power characteristics, the effects of gravitational force have not been discussed fully. Unlike other axes, power consumption of axes along the gravitational direction is influenced significantly by the movement direction, table position, and even by the machine configuration. In this study, power consumption of a five-axis machine was measured and analyzed. Experimental results showed that power consumption of a rotational axis is influenced not only by the position of the center of mass but also showed different characteristics in terms of movement direction. Furthermore, the rotational axis showed backlash characteristics, whereby the power was also influenced by the movement trajectory. With an understanding of power characteristics, a novel power consumption model was suggested for rotational axes. The model developed showed good agreement with measured values during verification with a sample part with various geometric features. By assessing the power characteristics of rotational axes, essential power coefficients for modeling can be determined. Furthermore, potential power saving strategies can be deduced from the power characteristics. Understanding the characteristics of power consumption of machine components can lead to design optimization and the use of phase process optimization to reduce energy consumption and lower environmental impact.