Study On Nonlinear Dynamic Characteristics Of Mandrel Oil Pressure Buffer

Hydraulic bumper is widely used in modern industry,most of the elevator lifts use hydraulic bumper nowadays.When the elevator fails to fall down,the hydraulic buffer will play a buffer protection role.It is the last safety protection device for the elevator operation.How to make the buffer more stable and protect the elevator equipment and the personal safety of crew members under high speed is a very worthwhile problem in engineering.The purpose of this thesis is to improve the cushioning performance of the mandrel hydraulic bumper.From the point of view of Engineering application,the dynamic characteristics of mandrel hydraulic bumper are studied,and the characteristics of throttling slot damping are analyzed and discussed.The dynamic behavior of mandrel hydraulic bumper is calculated and simulated,the hydraulic damping simulation system of the hydraulic buffer is built.The simulation results are analyzed,the optimized structure scheme of the mandrel hydraulic buffer is determined and the strength is checked.Finally,The purpose of optimizing the performance of the buffer is realized.The main contents include: We introduce the application background of hydraulic bumper for elevator,the structure characteristics,working principle,types and development status of the bumper and hydraulic bumper.We compare the differences of various oil bumper and the cushioning performance of different mandrel structure buffers.According to the ideal model of hydraulic bumper,study various parameters of hydraulic bumper such as the area of the throttling gap,the size of the outer surface of the mandrel,etc.The effect of buffer parameters such as throttle mouth diameter and mandrel height on cushioning performance is explained.According to the dynamics theory,the dynamic equation of the box is established.The dynamic equation of plunger is established based on fluid theory.Finally,the flow continuity equation of hydraulic fluid is established by combining solid structure.We take the contour of the outer surface of the mandrel and the inner diameter of the throttle mouth as a parameter and aim at reducing peak acceleration and extending buffer time,the optimal values of the parameters are theoretically analyzed,put forward specific design ideas and methods to determine the optimized structural scheme.A simulation system for hydraulic damping of hydraulic bumper is established with the MATLAB software,which simulates various working conditions of hydraulic bumper and carries out simulation calculation.By inputting parameters such as initial velocity,throttle size and mandrel size,the simulation system can generate velocity,acceleration time history curve and pressure curve.Through numerical simulation analysis,the impact phenomena in actual impact process are analyzed and discussed.Static analysis of key components by ANSYS Workbench software,the position of the larger stress point on the buffer,the corresponding stress value and the maximun deformation are obtained.The strength of the buffer is checked.Through the buckling analysis,the stability of the buffer is checked,which provides a scientific basis for ensuring the service life and structural reliability of the buffer.This thesis is an important part of the enterprise.According to the design requirements and relevant parameters provided by the enterprise,the above methods are applied to analyze and optimize the mandrel type hydraulic buffer.The structure of the buffer is finally determined according to the calculation results.The cushioning performance of the convex hydraulic bumper developed by the enterprise is much better than that of other bumpers.The parabolic hydraulic buffer proposed in this paper is further optimized on the basis of the convex structure.It can reduce vibration and noise more effectively,improve system performance and efficiency,make the buffer more stable and increase the safety factor of using elevator.This shows that the design method is feasible and practical.