METHOD OF MANUFACTURE OF ROTOR TUBULAR SHELL OF SCREW DOWNHOLE MOTOR Russian patent published in 2002 - IPC

FIELD: equipment for drilling of oil and gas wells. SUBSTANCE: the essence of invention consists in that forming of screw teeth on tubular shell is effected by action of fluid medium pressure with use of forming member with external screw teeth onto external surface of tubular blank. In this case, prior to withdrawal of forming member from formed tubular shell of rotor, lubricant is introduced under pressure into gap between them for expansion of tubular shell. EFFECT: provided easy withdrawal of forming member from formed tubular shell of rotor and prolonged service life of forming member. 2 cl, 4 dwg