| Budget Amount *help |
¥7,600,000 (Direct Cost: ¥7,600,000)
Fiscal Year 1999: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1998: ¥4,600,000 (Direct Cost: ¥4,600,000)
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| Research Abstract |
Recently, development of dry cutting method has been strongly desired because of reducing pollution in manufacture. In dry cutting, a high speed spindle is needed which can achieve large stiffness, high accuracy and low power consumption in high speeds. In this research, we propose a new type of infinitely stiff hydrostatic bearing with a miniaturized self-controlled restrictor in order to achieve the bearing performances mentioned above.
In a hydrostatic bearing for high speed spindles, low viscous lubricant is usually adopted to avoid an increase of bearing power consumption. Therefore, it is necessary to investigate the bearing characteristics of the proposed hydrostatic bearing for low viscous lubricant. We obtained the following results. (1).The inertia effect of lubricant is greatly influenced on the bearing characteristics when the lubricant with viscosity of less than 10 cSt is adopted. (2).The inertia of lubricant reduces the static stiffness. (3).The proposed bearing can stably operate even when low viscous lubricant is used.
Next, we discuss the new method to reduce the inertia effect of lubricant because this effect decreases the static stiffness. As a result, it was found that the static stiffness is greatly improved by using a porous restrictor instead of a capillary restrictor. This is because the porous restrictor can avoid the orifice effect, which occurs at the inlet of a capillary restrictor due to the inertia effect of lubricant. We investigated the static and dynamic characteristics of hydrostatic bearing with a self-controlled restrictor using a porous material. In addition, we applied this self-controlled restrictor to the hydrostatic journal bearing, and studied the static characteristics of the bearing, theoretically and experimentally. It was consequently found that the hydrostatic journal bearing with self-controlled restrictor using low viscous lubricant is very effective in achieving high stiffness, high accuracy and low power consumption.
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