Minebea Company, Limited

Akio Okamiya

Rikuro Obara

Toshisada Koyama

Masato Nasu

Takahiko Ito

A motor that can prevent damages on the fluid dynamic bearing. A ball is press-fitted into the end surface of the shaft body, and the ball is disposed in such a manner that the tip portion of the ball comes to the higher position with respect to the end surface of the annular body. When the shaft is at rest, the ball abuts against the upper surface of the counter plate, and the end surface of the annular body is brought into a state of being raised from the upper surface of the counter plate, so that the situation in which the end surface of the annular body and the upper surface of the counter plate are brought into almost fully touch each other can be avoided. Therefore, when the operation is started, the circulation speed of a fluid increases and a fluid layer is quickly formed. As a consequent, the fluid circularity blocking action, which could be occurred in the relate art, is avoided, and generation of scratch caused by starting rotation in the tightly sticked state can be positively prevented.

Motor

An oil repelling agent to coat a dynamic pressure device, such as a fluid dynamic pressure bearing device, includes a UV coloring agent, a fluorine-based polymer and a solvent. In an exemplary embodiment of the invention, the concentration of the UV coloring agent component is about 100 PPM to about 400 PPM, and the concentration of the fluorine polymer is about 0.1% by weight to about 0.6% by weight.

Oil repelling agent

In order to remove or decrease fine granular sulfides of Mn, Cr, Mo, etc. (Mn&#x2014;S, Cr&#x2014;S, Mo&#x2014;S, etc.) left on a machined workpiece surface of sulfur free-cutting alloy steel without affecting the form and dimensional accuracy thereof, there is provided a method for treating the sulfur free-cutting alloy steel which comprises a soaking process of the machined workpiece in a solvent and an ultrasonic cleaning process by applying ultrasonic waves of 1.0 to 2.0 W/cmin watt density at a frequency of 40 KHz or a multi frequency in the solvent.

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Miyota-machi, Japan

Akio Okamiya