Research On Machining Method Of Elliptic-like Progressive Cavity Pump Rotor

Oil recovery single screw pump is widely used in the oilfield by virtue of its small energy consumption,high efficiency,easy installation and other advantages.Twin-headed screw pumps have good prospects for development because of their high pump pressure and high head compared to single-headed screw pumps.However,double-headed screw pumps from the stator and rotor bone line outward equidistant generated contour line often due to the existence of bone line spikes and buckling phenomenon,resulting in meshing errors between the stator and rotor,affecting the performance and life of the oil recovery screw pump.The new elliptical cavity pump stator rotor profile are directly enveloped,without the need to do isometric curve to get the profile,to avoid the occurrence of the buckling phenomenon.In this paper,based on the analysis of the linear shape of the stator rotor of the elliptical cavity pump,we study the manufacturing and machining method of the rotor and analyze the influence of the machining parameters on the cutting force and the smoothness of the milling process.This paper analyzes the formation of the spiral surface of the rotor of the elliptical progressive cavity pump,proposes the method of machining the rotor by tangential envelope milling with the circumferential edge of the end mill according to the outer roll method,designs the transmission principle of the special tooling fixture that can be machined on ordinary CNC machines according to the forming method,analyzes the motion of the rotor machining process,and designs and calculates the parameters of the rotation mechanism.The motion analysis of the rotor machining process,the design and calculation of the transmission ratio parameters of the metric rotation mechanism,the realization of the specific planetary motion of the rotor workpiece,and the completion of the machining of elliptical rotors through the composite motion of the workpiece and the tool.The motion process of milling the rotor surface is studied,and then the mathematical model of tangential envelope milling is established,and the calculation methods of feed and milling speed are determined based on the mathematical model.To establish the helix equation of the elliptical rotor,determine the expression of the contour curve of the rotor shaft section,calculate the radius of curvature at the most concave point of the shaft section curve,and then determine the maximum size of the end mill for machining without interference with the workpiece;to study the generation of tangential machining error,determine its calculation expression,determine the location of the maximum machining error point of the rotor section and the variation law of the maximum error with rotational speed The main study is to determine how the tangential machining error is generated,to determine its calculation expression,to determine the location of the maximum machining error point of the rotor section and the variation of the maximum error with the speed.The finite element method is used to establish the tangential envelope milling model of the elliptical rotor using ABAQUS software,and the simulation results are analyzed by combining the three-way cutting force waveforms.The single-factor method was used to analyze the influence on the cutting force and the variation of the stability of the milling process by using the milling tool geometry parameters and the milling amount as the variable factors.Finally,the optimal combination of machining parameters for tangential envelope milling is obtained based on the analysis of the regularity results.