ROTOR OF A SCREW HYDRAULIC DOWNHOLE MOTOR, METHOD FOR ITS PRODUCTION AND A DEVICE FOR CARRYING SAME INTO EFFECT

摘要

ROTOR OF A SCREW HYDRAULIC DOWNHOLE MOTOR, METHOD FOR ITS PRODUCTION AND A DEVICE FOR CARRYING SAME INTO EFFECT A rotor of a screw hydraulic downhole motor, made as a hollow multiple-start screw featuring a substantially constant wall thickness. The ratio of the length of the rotor cross-sectional outside contour to the length of the circumscribed circle of said contour is substantially within 0.9 and 1.05. When making the rotor a forming element is inserted into a tubular blank, and a fluid pressure is applied to the outside blank surface. A device for making the rotor comprises a hollow housing accommodating a forming element installed on centring bushings. The bushings have fitting areas adapted for the ends of the tubular blank to fit thereon.