Statics And Dynamics Study Of The Double-screw Pump Rotor

B-type double-screw pump is a sealed-type screw pump, suitable for high-pressure andlow-flow conditions. At present, more research in vibration of a single screw has completed, andresearch of gear coupling is very little on the impact of the vibration characteristics of thedouble-screw. Rotor system Containing gear drive has obtained a wide range of applications andit has become an important area of research in the rotor system. Due to the meshing of the gears,it makes the bending vibration and torsional vibration of rotor coupled to each other, thusdynamics characteristics of the rotor system is examined not only from the single rotor. So thepaper must establish a system coupling frequency equation including bending vibration andtorsional vibration to analysis the dynamics characteristics. Aim at HZW170B double-screwpump, the paper has studied design of screw profile, static analysis and dynamic analysis.The spiral surface of screw is formed by screw motion of the end section lines of screwaround the axis of screw. Research of screw type line is the key to guarantee and improve theperformance of screw pump. In this paper, Vector algebra method is used and vector equation ofthe surface of B-type double-screw is derived. According to the principle of the formation of thescrew section line, the paper derived the equation of screw end line, meanwhile. Combined withthree-dimensional mapping software SOLIDWORKS, the paper draw entity diagram of screwand assembled them.The bending deformation of the screw would cause wear of the threaded sleeve, so researchof screw static stiffness is very important. By ANSYS software, the paper used three-dimensionalbeam element to simulate screw and got the deflection curve of screw. At last, the paper got themaximum deformation of the screw. It provided a theoretical basis for the gap set between thescrew and the threaded sleeve.Then based on theoretical knowledge in gear bearing rotor system dynamics and calculationparameters of the B-type double-screw, the paper built finite element model of the parallel shaftgear rotor system, and completed its dynamic analysis using software ANSYS. The papercompleted comparative analysis of dynamic characteristics of each rotation axis of parallel shaftgear bearing screw rotor system in the uncoupled and coupled state. The results show that, due tothe engagement of the gear, the bending vibration and torsional vibration of the gear rotor systemis coupled and vibration between the rotorsis coupled. If not considering the engagement of thegear, the results will lose natural frequency due to the coupling between the rotors.Finally, the paper tested the natural frequency of the B-type double-screw, the resultsshowed that double-screw rotor appeared some new natural frequency due to coupling of gears.Comparing the test results and the calculated results, theoretical and practical results arerelatively close.