The Movement Simulation And Load Bearing Characteristic Research Of Planetary Roller Screw

Planetary roller screw (PRS) is a transmission mechanism which can mutually convert rotationand linear motion by thread driving. PRS combines the kinematics performance of planetary gear train,ball screw and needle roller bearing. Through setting several planetary thread rollers, the contact areaof PRS can increase greatly. PRS has outstanding advantages of large carrying capacity, hightransmitting precision and long service life.Working principle is introduced of standard type of PRS and inversion type of PRS. Parametercalculation formulas of major parts are inferred and three dimensional models of PRS are built byCATIA. Pitch circle mismatch between roller thread tooth and internal gear circle thread tooth isdiscussed, relative slip velocity and axial displacement between rollers and nut due to the mismatch isanalyzed. Velocity values of nut and screw are obtained through kinematics simulation for these twokinds of PRS by ADAMS, which are verified by comparing with theoretical values. The velocitychanges situation of nut and screw under limit load are researched by setting up contact conditionsbetween rollers and screw or nut, and the reason of the fluctuation is discussed. Working torque iscalculated between thread tooth of roller and internal gear circle or nut.Finite element models of the PRS are set up by ANSYS Workbench. Equivalent stress andstrain distribution are predicted of rollers, screw and nut under limit static load. Strain distribution ofroller and screw caused by different thread angle is analyzed，and influence on the maximum totaldeformation of screw and nut due to different numbers of roller is researched. Bending deformationunder gravity and pith error caused by this deformation are calculated, two kinds of methods tominimize the error are put forward.Modal of PRS is analyzed through finite element simulation technology, six-order inherentfrequency is calculated and vibration shape diagrams are obtained. Influence on inherent frequencyand total deformation of PRS is studied in consideration of supporting patterns, working position ofnut and centrifugal force due to rotation.