Interference Type Locking Hydraulic Cylinder Design And Stress Analysis

This thesis mainly studied locking structure design and check method in the interference locking hydraulic cylinder.Interference locking hydraulic cylinder,as a new type of mechanical locking hydraulic cylinder,adopts unique interference locking technology,which has advantages like passive locking at any places,strong carrying capacity upon locking,capability of long-term locking and simple structure.Targeted at key issues like wall thickness of the cylinder,size of the locking sleeve and determination of magnitude of interference in fitting surface,it proposed a design calculation method and optimization principle as well as presented a check method in this thesis,providing certain references to the design of the hydraulic cylinder.With the advancement of modern materials technology and industrial manufacturing capability,control on interference fit has been really accurate.Interference locking hydraulic cylinder is a new application based on technology of interference fit.In this paper,based on the theory of thick-well cylinder,it explored deformation and stress of contact surface of the cylinder and the locking sleeve under the effect of axial symmetric uniformly distributed load as well as proposed a computational formula for computing magnitude of interference of the cylinder and the locking sleeves with combination of fitting relationship between the cylinder and the locking sleeve;At the same time,a check method of the cylinder wall thickness and stress was deduced according to the third strength theory.It also discussed optimization of interference,assembly process,material selection and influence of temperature on the locking,etc.with combination of engineering practices.Computational steps were summarized and designed as per theoretic design methods of this thesis.A computational model of input and output was set up with utilization of Matlab software;Design size and value of interference of the cylinder and the locking sleeve were obtained through computing design examples.Finite element method was adopted to check the design method proposed in this paper;SolidWorks,according to the size,was used for building 3D entity model that was imported into ANSYS software for simulation.Simulation results showed that surface contact pressure of the cylinder under locking state were basically consistent with the analysis solutions obtained during design computation;Moreover,stress was proved to satisfy requirements of supporting loads and stress of the cylinder and the locking sleeve were conformed with requirements of allowable stress;The cylinder and the locking sleeve were still contacted under locking state,but the magnitude of interference was decreased to be ignored and stress of the cylinder and the locking sleeve were still within the scope of allowable stress.At last,ANSYS was employed to analyze the influence of temperature on the locking state of hydraulic cylinder,results of which showed that temperature would have a large influence when there was a larger gap in linear expansion coefficients of the cylinder and the locking sleeve.Upon analyzing on the above results,it can be concluded that the computational method of interference proposed in the thesis could not only satisfy the requirement of nonoccurrence of plastic deformation,but also consider factors like low cost of tolerance for processing size of the interference,etc.Stress value was reasonable upon locking,reaching perspective design goal.The thesis could provide a certain reference to production and design of hydraulic cylinders.