| Budget Amount *help |
¥5,900,000 (Direct Cost: ¥5,900,000)
Fiscal Year 1998: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1997: ¥4,100,000 (Direct Cost: ¥4,100,000)
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| Research Abstract |
Recently, the size of many electric and photo-electric devices has been reduced and printed circuit-boards used in these devices have been also required to be smaller. Accordingly, the diameters of small holes for fixing electric parts on the printed circuit-board have to be reduced. Water-lubricated hydrostatic conical bearings with spiral grooves were designed for high speed spindle to drill these small holes on printed-circuit boards. Comparing with oil-based hydrostatic bearings, water-lubricated hydrostatic bearings have lower power consumption at high speeds and do not have the environmental problems. In addition, this bearing has larger load capacity than aerostatics bearings since higher supply pressure can be used due to the incompressibility of water. Researchers have already investigated the bearing characteristics of a water-lubricated conical bearing for high speed spindles.
In this study, a high speed spindle using the proposed bearing was developed. Various bearing performances such as rotational accuracy, load capacity, stiffness, torque and temperature rise, were measured. It was found that the developed spindle is excellent performances for drilling machines. Furthermore, drilling test at speed of 140,000 rpm was performed because it is important for this kind of spindle to be able to achieve high accuracy of hole shape and hole position. From this test, it was clearly demonstrated that the developed spindle can achieve excellent drilling performances.
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