Design and Research of Micro Pneumatic Machining System Integrated with Aerostatic Bearings
Date Issued
2010
Date
2010
Author(s)
Ting, Guan-Chung
Abstract
Because of advantages such as high-speed operation, low-energy consumption and low-heat emission, pneumatic drilling systems are widely used in the fields of machining tools and dental equipments. In order to further increase their working speed and efficiency, they must rely on efficient bearings with low-friction and less-vibration.
In this thesis, a new type of micro pneumatic machining system integrated with aerostatic bearing is designed and developed. A serial configuration of “Twin-Powered Micro Turbine”, which is co-developed by the Precision Engineering Laboratory of NTU and MicroP Technology (Taiwan) Inc., is applied to enhance the energy transformation efficiency. And the high-speed rotor shaft is axially and radially supported by our developed aerostatic bearings, which can provide a low-friction and less-vibration operation. In order to improve the machining performance on hard materials, an axial vibration device is also applied to integrate with the rotational drilling device.
The whole system consists of power, bearing, clamping and vibration subsystems, which are modular constructed for convenient maintenance and modification. The systematic design approach begins with the core-element: micro turbine, and the conceptual and embodiment designs are progressively accomplished.
Through theoretical analysis and finite-element-method, the influences of the design and operational parameters on its system performances such as rotational speed, torque and bearing capacity are studied. Besides, the analyses are used to optimize the design parameters. And the experimental tests are also focused on the system performances and the cutting efficiency.
By the supply pressure of 4.0 bar for the turbine, the developed micro pneumatic machining system achieves a maximum rotational speed of 280 krpm and a maximum torque of 6.05 Nmm. And the average clamping force for machining tool can reach 6.05 kgf. Through the integration with the axial ultrasonic vibration, its cutting capability on the stainless steel achieves about 26 mg/min and is 1.5 times higher than that without axial ultrasonic vibration. The aerostatic bearings also perform their low-friction bearing capacities for the turbine.
Subjects
Micro pneumatic machining tool
Twin-powered air turbine
Aerostatic bearing
Modularization
Compound dynamic measurement
SDGs
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