Machining, Measurement, and Control Laboratory

Development of a High-Performance Spindle for Multitasking Machine Tools
Taku Yamazaki, Toshiyuki Muraki, Atsushi Matsubara, Mitsuho Aoki, Kenji Iwawaki, Kazuyuki Kawashima

In recent years, high-performance spindles are required for multi-tasking machine tools to enhance the productivity. Such spindles enable efficient rough cutting and fine finishing of a workpiece on one machine. In order to meet this requirement, a spindle unitmust be highly stiff and operate at high rotational. Spindle specifications require a rotational number of 50,000 min-1 and dN value of 3,000,000, a smaller motor was downsized and an electric loss restrained by reducing the thickness of laminate sheets composing the rotor core. A direct-injection type of ultra trace quantity lubrication and a preload switching system were used for ball bearings for high rotational speed and high stiffness. We discuss how these technical requirements were met and the results of basic experiments.
Key Words:   machine tools, dN value, high speed spindle, spindle displacement, preload switching