Method of manufacturing vacuum pump rotors, and rotors obtained thereby

Abstract

A rotor having a set of radial peripheral vanes for a high vacuum turbomolecular pump is manufactured by forging a metal workpiece to obtain a generally cylindrical body ( 1,11 ) with homogeneous mechanical properties and subsequent mechanical workings.

What is claimed is:  
     
         1 . A method of manufacturing a rotor for a high vacuum turbomolecular pump, comprising the steps of: 
 providing a workpiece being made of a material suitable for producing of said rotor;    forging said workpiece to obtain a generally cylindrical body( 1 , 11 ) having a homogeneous mechanical properties, and    obtaining one or more sets of radial peripheral vanes thereon.    
     
     
         2 . The method of  claim 1 , wherein said generally cylindrical body is a cylindrical billet ( 1 ) that is obtained by forging through an axial compression (P 1 ) thereof while preventing at the same time its radial expansion.  
     
     
         3 . The method of  claim 1 , wherein said rotor is a bell-shaped rotor.  
     
     
         4 . The method of  claim 3 , further comprising the steps of: 
 forging said generally cylindrical body being a cylindrical billet ( 1 ) through an axial compression (P 1 ), and    subsequently forming a cavity within said cylindrical billet by means of a punch ( 12 ) that is forced into the billet, while preventing at the same time radial expansions of the billet through confinement in a mold.    
     
     
         5 . The method of  claim 4 , wherein the steps of forming a cavity comprising extending said cavity ( 13 ) over a part of said cylindrical billet and refining by subsequent mechanical working.  
     
     
         6 . The method of  claim 5 , further comprising the steps of forming of a central bore on a bottom of said cavity and subsequently providing a thermal treatment for improving mechanical properties of said bell-shaped rotor.  
     
     
         7 . The method as claimed in any preceding claim, further comprising a step of processing said at least one set of radial peripheral vanes by one or more techniques selected from the group consisting of milling, turning and electric discharge machining.  
     
     
         8 . A rotor for a turbomolecular pump produced by the method of  claim 1 .  
     
     
         9 . The rotor for a turbomolecular pump of  claim 8 , having parameters R, A and R 0.2  that are constant in all directions throughout of said rotor.