Development of an automatic variable preload device using uniformly distributed eccentric mass for a high-speed spindle

The variable preload method varies preloads according to rotation speed and operational conditions. Variable preload technology is necessary when performing machining processes under both low and high speed conditions. The author suggested the concept for an automatic variable preload device using an eccentric mass in a previous study. This study develops and evaluates an automatic variable preload device using a uniformly distributed eccentric mass for practical use. It can help increase preload efficiency by increasing the eccentric mass. A finite element analysis is performed and the results confirm the deformation of a uniformly distributed eccentric mass device according to its rotation speed. Based on the analysis results, a spindle prototype subjected to a maximum speed of 10,000 rpm is fabricated. The axial force of the uniformly distributed eccentric mass device is measured during operation and the results confirm that the variable preload operates effectively.