Research On The Rolling Forming Method Of The Stator Of The Screw Drill With Equal Wall Thickness

Petroleum exploration and development are facing enormous challenges as oil reservoir moving to the deep strata.Exploiting resources with high-efficiency and low-cost has become an urgent problem to be solved in the present petroleum industry.The screw drilling.as the assistant tool,it improves the rock-cutting efficiency and plays a significant role in compound drilling.Nevertheless,the average service life of conventional screw drilling in deep and ultra-deep wells is only 40?60 hours,which is far less than the engineering expectancy life 150 hours.With the advantages of good heat dissipation,tightness,and mechanical properties,the service life and output power in deep well drilling are improved by the iso-wall thickness screw drilling.which demonstrates the broad prospects for progress.The core component of the iso-wall thickness screw drill is the screw motor.By changing the straight circular cylindrical shell of the conventional screw motor to the spiral surface structure,the rubber bushing which is vulcanized on the inner wall of the shell with uniform thickness.Therefore,it is significant to find a manufacturing process that meets the requirements of the manufacturing precision,the performance reaches the standard and can produce a large number of spiral surfaces of the stator shell.This paper mainly studies the following aspects:The rolling forming process of the iso-wall thickness stator shell was proposed,By using the finite element analysis software DEFORM-3D,the four kinds of rolling schemes,namely,a single wheel rolling.multi wheel rolling,one pass rolling and multi pass rolling were simulated.Multi wheel and one pass rolling were an ideal forming processAfter determining the rolling process scheme,the effects of rolling speed,lubrication condition,wheel structure,wheel size and rolling temperature on forming the type of 5LZ73×7.0 iso-wall thickness stator shells are discussed.It is found that when the preheating temperature of 42CrMo tube is 800?1000?,the rolling speed is 5mm/s.the radius of the wheel is 60mm,the curvature of the wheel rolling surface is 6-8mm and the composite lubrication method has the best forming effect.The mechanical model of the roll-forming is set up.On the basis of the unit pressure differential equation by Karman.the rolling-force formula is obtained.According to the formula,the rolling pressure size depends on the size parameter of the wheel,the thickness of the tube wall,the method of lubrication,the feed parameters and the material.According to the rolling parameters provided by the finite element simulation,iso-wall thickness stator with OD 73mm was analyzed with the method of roll forming experiments.The diameter,wall thickness,lead and tube length variation of four sets of stators formed under different tube materials and feeding modes were measured.The influence of different pipe material and rolling method upon forming quality was studied with the method of two-way ANOVA and main effect plots quantitatively.Finally,the structure of the roll forming multi head feed device is preliminarily designed.