| At present,the erecting mechanism of missiles in China is mainly driven by hydraulic cylinders.Because of inefficiency of hydraulic cylinders,the easy leakage of hydraulic oils and the difficulty of maintenance have limited the development of the erecting performance of and launching performance of missiles.Therefore,it is imperative to replace the traditional hydraulic cylinder with the electric cylinder which has the advantages of high transmission efficiency,no leakage risk and convenient maintenance to realize the electric drive of the erecting mechanism.The existing ball screw electric cylinder can not meet the heavy load requirements of the missile erecting mechanism.The existing ball screw electric cylinder can not meet the heavy load requirements of the Missile Erecting mechanism.Therefore,this paper will complete the design and research of the electric cylinder suitable for the missile erecting mechanism based on the two-stage planetary roller screw mechanism which has higher load-carrying capacity and longer life than the ball screw.In this paper,the motion and force of each part in the PRS are analyzed to derive the relationship between the parameter relationship between the PRS parts and the screw propulsive force.The overall structural scheme of the secondary PRS is selected according to the motion characteristics and usage requirements of the PRS,and the PRS performance is analyzed.The relationship between the index and the design parameters is selected,and the design parameters affecting the main performance of the PRS are selected.By analyzing the force of the three-hinge point and the vertical mechanism,the position of the hinge of the vertical mechanism is optimized,and the stroke and motion force of the two-stage PRS electric cylinder are calculated.The critical dimension design of the secondary PRS is the basis for designing the electric cylinder.Based on the genetic algorithm,the main screw radius,spline working height,secondary screw thickness,tooth side angle and screw pitch of secondary PRS are taken as design variables,and the transmission efficiency,radial dimension and service life of secondary PRS are taken as objective functions.For the objective function,the overall objective function is established by the analytic hierarchy process and the single objective optimization to obtain the optimized variable group,and based on the optimized design variable group build the virtual prototype is established.The kinematics and dynamics of the electric cylinder affect the performance and reliability of the vertical mechanism.The kinetic analysis of the electric cylinder virtual prototype by ADAMS obtains the rotational speed,angular acceleration and axial speed of the secondary electric cylinder,and analyzes whether the full deployment time of the electric cylinder meets the design requirements;using the ANSYS Workbench to fully deploy the working cylinder The buckling analysis was carried out to analyze the modal analysis and harmonic response of the secondary PRS mechanism and the starting,balancing and stopping phases of the electric cylinder respectively,and to study the dynamic characteristics of the secondary PRS and the electric cylinder as a whole.When the electric cylinder is working,the error of PRS mechanism will affect the accuracy of the motion of the electric cylinder.According to the transmission sequence of the two-stage PRS mechanism,the transmission error of the mechanism is analyzed the error source and the error calculation equations are established,and the error is comprehensively calculated.The error influence matrix is analyzed to analyze the influence of single error on the transmission precision,and the comprehensive error of the system is calculated.The influence of parameters on the transmission error;Finally,the calculation software of the two-stage PRS electric cylinder was developed by using the Gui module of Matlab to simplify the design calculation process. |
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