Papers by Keyword: Spiral Groove

Abstract: An analysis is performed on the tracking property of a spiral groove dry gas seal (DGS) operating in low pressure conditions based on a semi-analytical method developed by Miller and Green. The stiffness model of gas film is established by solving compressible Reynolds equation. And the stiffness model is applied to the kinetic model of seal ring to obtain tracking movement of seal ring. The influences of seal ring face geometry parameters, namely the spiral angle, the groove depth, the groove-dam ratio and the groove-land ratio, on tracking property are evaluated by a series of analysis. Recommended values of such parameters are given as a result of parametric design, to improve tracking performance of DGS in low pressure condition, which one can refer to in turbine compressor spiral groove DGS designs.

Abstract: This research explores the micro-forming process of spiral groove pattern on Fluid Dynamic Bearing(FDB), which is utilized in precision driving part of the hard disk drive(HDD), using micro desktop forming system. While EDM and ECM process has been widely used to engrave the precision pattern which generates dynamic pressure on FDBs, micro forming process is newly proposed in this study to increase the productivity and to reduce the product costs. At first, desktop forming system is designed for spiral groove pattern forming. FE simulations are followed in order to evaluate the feasibility of micro-forming. The simulation results show that forming loads of 1,500Kgf is required to fabricate micro patterns with the depth of 15 μm. Finally the formability test is carried out with various forming loads. Deformed shapes and forming loads obtained from the test are compared with those from the analysis. The results fully demonstrate that micro pattern forming techniques are available to fabricate micro spiral groove patterns in FDB.

Abstract: The three dimensional model was established for studying performance of spiral groove gas face seal. According to machining features of different surface area, the seal face can be divided into three parts, rotor ring grooved area, rotor ring non-grooved area and static ring area. The effect of roughness on seal performance was analyzed based on calculation of three dimensional flow field. The analysis results show that the surface roughness of rotor ring grooved area has great influence on the seal performance, but the influence is little when roughness on non-grooved rotor ring surface and static ring surface. The influence must be considered when surface roughness of rotor ring grooved area bigger than 0.2μm. Roughness of rotor ring surface can increase the loading force while it also can cause the increase of leakage. It is important to select rational roughness when designing gas face seal.

Abstract: Base on the conventional twist drill, the new type of solid carbide twist drill which the length-to-diameter radio (L/D) is about 12 was developed with improved parameters of drill point and flute geometry. Study of intensity and rigidity of drill was performed by using analysis software ANSYS Workbench for the theoretical support and technical guidance for the design of twist drill. Tests were carried out to compare the new drills with the competitive drills in terms of tool life, chip breaking, and chip disposal. The results obtained from tests indicated that the new type twist drills have similar cutting capability compare to the competitor’s drills.

Abstract: The thermo-hydrodynamic effect in the spiral groove mechanical seal was investigated. The coupling analysis of the fluid film and the thermal deformation of sealing rings was carried out, the separation angle obtained, and the shape of the gap between the two deformed end faces determined. The results indicate that the increase of the temperature of the fluid film and the thermal deformation of the sealing rings cause the increase of the leakage rate. There exists a critical rotating speed, when the rotating speed is lower than the critical speed, the bearing force increases with the increase of the rotating speed, and once the rotating speed is higher than the critical speed, the bearing force decreases reversely. The thermal deformation weakens the hydrodynamic effect of the spiral groove mechanical seals.