Design and Research of Pneumatic Drilling System Integrated with Cap-shaped Hybrid Aero Bearing
Date Issued
2012
Date
2012
Author(s)
Wang, Chun-Jui
Abstract
Because of progressive development of 3C products, the demand of high-speed PCB drilling machine tools is rapidly increasing. However, traditional drilling machines driven by electromagnetic motors always involve some drawbacks such as resistive heating and low-speed limitation. Instead of electromagnetic motor, this thesis proposes the concept of air turbine for developing a novel drilling tool. With the advantages of high-speed, simple construction, and self-cooling, the application of air turbine can improve the performance of PCB drilling machine tools. High-performance bearing can further enhance the rotation performance and stability of drilling shaft, and it also possesses the characteristics of self-cooling, no-wear, and low-noise. In this thesis the aerostatic bearing assisted by an aerodynamics bearing is developed to support the rotor of the air turbine, and this hybrid aero bearing is designed in a cap-shaped form to stabilize the air-gap pressure in order to increase the rotational stability.
Through the theoretical analysis, the performances of air turbine the aero bearing are separately analyzed. And the CFD software is also used to simulate the pressure and stream distribution inside the aero bearing in order to comprehend functionality and to derive optimized design parameters. Based on the analytical results, the pneumatic drilling system is integrated with the cap-shaped hybrid aero bearing, which is built up with changeable modular construction. Its power, capacity, and cutting performance are experimentally verified. Through the comparison between the analytical and experimental results, the error analyses are carried out and the improvement proposals are derived.
The drilling system achieves a maximum rotational speed of 6388 rpm and a maximum torque of 37.38 N∙mm under the supply pressure of 2 bar. Through supporting by the cap-shaped hybrid aero bearing, its axial and radial loading capacities are 5.13 N and 1.65 N, respectively. The standard PCB-board can be drilled through in 9 s, and its diametrical error is smaller than 4%, and its roundness 46 um.
Subjects
PCB drilling machine
Air turbine
Cap-shaped
Aerostatic bearing
Aerodynamics bearing
Hybrid aero bearing
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
index.html
Size
23.49 KB
Format
HTML
Checksum
(MD5):9006851b5fff860f15d0b6b5f3a324f3