Study On Parametric Design Of High-speed Small Compound Molecular Pump

As an important equipment in obtaining high vacuum and ultra-high vacuum environment,compound molecular pump is widely used in semiconductor,aerospace,nuclear industry and film field,and many kinds of compound molecular pump have been designed over the past few decades.The traditional design method,however,with disadvantages of involving many parameters,complex calculation formula,repetitive revisions and low efficiency,obviously no longer meet the needs of contemporary development of compound molecular pump,the development of new design method is imminent.In recent years,with the development of computer technology,CAD/CAE is widely used in the field of mechanical design.At the same time,parametric design theory has been continuously improved,provides a new idea for the design of compound molecular pump.Based on this,this paper studies compound molecular pump parametric design technology,and develops a parametric design system of it.Based on research of structural characteristics,design method and performance evaluation of compound molecular pump,using SolidWorks as development platform,Visual Basic 6.0(VB)as development tool,combined with parameters design technology,OLE automation technology,ActiveX automation technology and database access technology,develop an integrated system of compound molecular pump parametric design:(1)The process of compound molecular pump design and calculation are studied,and parametric design flow is determined.Using VB,the design and calculation system of compound molecular pump is developed.The system uses the man-machine interaction interface to input information,realizing the automation of parameters determination and dimension calculation in designing of the main parts of compound molecular pump.The system has three kinds of design schemes,can calculate three groups of structural parameters at the same time,and then through the system automation analysis or user choice,determine the optimal design scheme.(2)Pumping performance of compound molecular pump single blade arrange is studied,and put forward an integration average method to improve turbo pumping performance.Based on Navier-Stokes equation,deducts the pumping performance calculation formula of drag cylinder,and writes compound molecular pumping performance calculation program with VB,and develops pumping performance computing system combining with man-machine interaction interface.(3)Modeling characteristics of compound molecular pump main parts is studied,and 3-D models of main parts are established by using program drive and dimension driving methods.Based on parametric modeling,using constraints and local sketches with reference plane assembly methods,introduces associated parameters and constraints into parts assembly,and eventually establishes 3-D model of compound molecular pump.(4)The design and calculation system,performance calculation system,parametric modeling system are integrated,and the interface program is written by VB,and then completes the development and release of the entire parametric design software.In order to prove the feasibility of parametric design method in the field of compound molecular pump design,and evaluate the reliability and accuracy of the parametric design software,this paper makes calculation test using the compound molecular pump model provided by the "fund".The result shows that,parametric design software gets good agreement both in performance characteristics and structure parameters of main parts,compared with traditional design method.At the same time,parametric design method has the advantages of high efficiency,high degree of automation,low cost,and is worth to be promoted.