| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 2003: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥3,400,000 (Direct Cost: ¥3,400,000)
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| Research Abstract |
Recently, the size of devices associated with information has been rapidly reduced.Accordingly the diameter of holes in printed circuit boards installed in these devices is getting smaller and the demand of higher rotational speed of more than 200,000 rpm is also increasing for drilling spindles to manufacture small holes.Considering the future trend for miniaturization in these devices, high speed spindles with rotational speed of more than 300,000 rpm has to be developed.
In this research, we proposed aerostatic journal bearings with a porous floating bush to improve the stability of a rotor supported by aerostatic bearings at high speeds.In the proposed bearing, pressurized air is fed only to both floating bush ends, but both the outer and the inner walls of a floating bush can function as an aero static bearing due to the effect of porous material.In addition, a very small gap at both ends of a floating bush can avoid the pressure reduction of pressurized supply air, which makes this porous bearing maintain stiffness and load capacity comparable to an ordinary porous bearing. We theoretically investigated various performances of the proposed bearing such as load capacity, stiffness and instability at high speeds.Then we manufactured the proposed floating bush journal bearings based on, the theoretical calculations and compared experimental results with theoretical calculations.As a result, the following conclusions were obtained.
(1).It was experimentally confirmed that the proposed aerostatic journal bearing with a porous floating bush has an excellent stability at high speeds.
(2).The validity of theoretical calculations was confirmed by comparing them with experimental results.
(3).It was found that the manufactured high speed spindle using the proposed bearings has excellent performances as a drilling machine for very small holes.
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