Optimizing loading path and die linetype of large length-to-diameter ratio metal stator screw lining hydroforming

In order to meet the high temperature environment requirement of deep and superdeep well exploitation, a technology of large length-to-diameter ratio metal stator screw lining meshing with rotor is presented. Based on the elastic-plasticity theory, and under the consideration of the effect of tube size, material mechanical parameters, friction coefficient and loading paths, the external pressure plastic forming mechanical model of metal stator screw lining is established, to study the optimal loading path of metal stator lining tube hydroforming process. The results show that wall thickness reduction of the external pressure tube hydroforming(THF) is about 4%, and three evaluation criteria of metal stator screw lining forming quality are presented: fillet stick mold coefficient, thickness relative error and forming quality coefficient. The smaller the three criteria are, the better the forming quality is.Each indicator has a trend of increase with the loading rate reducing, and the adjustment laws of die arc transition zone equidistance profile curve are acquired for improving tube forming quality. Hence, the research results prove the feasibility of external pressure THF used for processing high-accuracy large length-to-diameter ratio metal stator screw lining, and provide theoretical basis for designing new kind of stator structure which has better performance and longer service life.

Characterization of a-Si:H/SiN multilayer waveguide polarization using an optical pumping application—LED

This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode(LED) pumping lights to its surface.By using double tubed coaxial line(DTCL) microwave plasma chemical vapor deposition(MPCVD) equipment,an a-Si:H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer order.The main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon nitrate.Once the sample was ready,another major objective of the experiment was to analyze the polarization characteristics of the fabricated waveguide.The idea of the experiment was to analyze how the waveguide reacts when three types of LED(blue,yellow,and red) are radiated onto its surface.The results showed that the fabrication of the a-Si:H/SiN sample is successful.Most effective transmission results,which accord with the polarization characteristics analysis,were obtained.