METHOD OF MANUFACTURING ROTOR OF SCREW-DOWNHOLE MOTOR Russian patent published in 2002 - IPC

FIELD: technique of construction of wells, particularly, rotors of screw downhole motors for drilling of oil and gas wells; applicable in production of oil and gas. SUBSTANCE: method includes shaping of profile of spiral tooth o produce intermediate profile of teeth in end face section in accordance with expressions x_o=x-λ Sin v and y_o=y-λ Cos v, where x, y are coordinates of nominal profile of rotor; v is an angle of inclination of tangent to nominal profile of rotor; λ is deviation of rotor profile from nominal over perpendicular to it which is increased from tooth space to cog of rotor spiral tooth; application of wear-resistant coating to obtain nominal profile. Deviation λ of rotor profile from nominal over perpendicular to it is calculated by formula λ= (0,5(λ_a+λ_f))(1+coszδ)-λ_f+(λ_s-0,5(λ_a+λ_f))sin²zδ,, where δ is a polar angle of rotor nominal profile; z is a number of rotor teeth; λ_a is thickness of wear-resistant coating at teeth points; λ_f is thickness of wear-resistant coating in tooth spaces; λ_s is thickness of wear-resistant coating on sides of teeth at middle of their height. EFFECT: nominal profile by wear-resistant coating, higher accuracy in engagement, reduced leakage of drilling mud due to formation of corrected profile on rotor, and increased service life. 4 cl, 3 dwg