Session: FSI-01-01 Thermal Hydraulic Phenomena with Vessels, Piping and Components-1

Paper Number: 122879

122879 - Study on the Discharge Characteristics of Multi-Hole Nozzles and Feasibility Verification for Built-in Nozzle Flapper in Air Spindle 

In recent years, due to the growing demand for semiconductors, there is a need to increase the rotating speed and improve the machining accuracy of the semiconductor-processing spindles to achieve a higher processing efficiency. Spindles, loaded with aerostatic air bearings, were proposed as a feasible solution to achieve higher rotating speed, but as for the higher machining accuracy of the semiconductor, still lacked a cost-effective position measurement method as part of a compensation strategy for the shaft’s offset due to the processing resistance load and high rotating speed of the shaft. In our previous research, the feasibility of utilizing a pneumatic nozzle flapper as a distance sensor for measuring the distance to a shaft rotating at 20,000 rpm was validated. Static and dynamic characteristic experiments were conducted on a single nozzle flapper system, and conclusions were drawn regarding the influence of relevant structural and fluid parameters on the static and dynamic characteristics.

In this report, we will initially conduct an in-depth investigation into the effects of the number of holes, hole diameter, and hole spacing on the discharge characteristics of the multi-hole nozzle flapper. And, in combination with various diameters orifices and different sizes of rotating bodies under varying supply pressure conditions, we will investigate the static characteristics of the multi-hole nozzle flapper system, including the sensitivity of pressure variation with distance and the range of the linear region. Through experiments, we will validate the mutual influence of hole spacing on multi-hole nozzles and elucidate the characteristic outcomes of multi-hole nozzles based on and in conjunction with other relevant theoretical phenomena. Analyze the dynamic reasons leading to resistance in the discharge of multi-hole nozzles and the limitations caused by structural parameters. We will also design two types of built-in our-nozzle flapper structures (integral and embedded) that can be incorporated inside an air spindle based on our previous research. We experimentally verify the symmetry of the measurement characteristics of the four-nozzle flapper in the coaxial direction, demonstrating the feasibility of independently modeling the four nozzles. Through experiments, we examine the static characteristics of the two nozzle flapper types and analyze the reasons for their differences compared to nozzle flapper characteristics in an open space. We determine the optimal structural parameters for the static characteristics of the two types of nozzle flappers and finally experimentally verify the existence of an optimal critical size for the gap in the integral-type nozzle and provide its corresponding fitting equation. We will establish, for the first time, a 3D computational fluid dynamics simulation model for the pneumatic nozzle flapper, and validate the simulation results by conducting experimental measurements for comparison. Furthermore, we will employ the data obtained from the 3D fluid simulation to provide a theoretical explanation for the discharge characteristics of the nozzle. This will involve analyzing and interpreting the influence and correlations of structural dimensions such as the distance between the nozzle and flapper, initial clearance, rotating flapper’s diameter, on the discharge impedance of the nozzle. Additionally, we will conduct a reverse analysis to understand the mechanical effects of the nozzle on the rotating flapper when the rotating flapper is vibrating, resulting from changes in control pressure due to distance variations. Finally, we will assess the impact of the nozzle flapper itself on the stability of the rotating system.

Presenting Author: Peimin Xu Tokyo Institute of Technology

Presenting Author Biography: PhD student in Inaba Lab, Tokyo Institute of Technology

Authors:

Peimin Xu Tokyo Institute of Technology
Kazuaki Inaba Tokyo Institute of Technology
Hisami Takeishi Tokyo Institute of Technology
Toshiharu Kagawa Tokyo Institute of Technology