Multi-stage Hydraulic Cylinder Research Articles

Study on Critical Load for Multistage Hydraulic Cylinder

To prevent the appearance of buckling failure when the multistage hydraulic cylinder works, the finite element of compression rod simplified model instead of multistage hydraulic cylinder is established based on the importance of engineering safety operation. The linear and nonlinear buckling analysis for compression rod can be realized by the finite element analysis software called ABAQUS. Meanwhile, the value of critical load for compression rod can be calculated and compared from two aspects of linearity and nonlinearity. The results indicate that the value got from nonlinear buckling analysis is more conservative than linear buckling analysis and the value of critical load is proportional to the cross section area.

Modeling and Jitter Suppression Analysis of a Lifting Multistage Hydraulic Cylinder

In view of the abnormal phenomena in the movement of the 4-stage hydraulic cylinder, this paper establishes the basic motion model of the multi-stage hydraulic cylinder by melting point nodal cavity method, and analyses the variation law of its external load. On this basis, the erection process of the multi-stage hydraulic cylinder is simulated and analyzed by AMESim, and it is found that the sudden change of pressure at the change of the stage will cause the vibration of the multi-stage. Found that the abnormal vibration of the third piston occurs during the retraction process of the hydraulic cylinder, which is caused by the insufficient guide distance of the 3 stage piston of the multi-stage hydraulic cylinder. The sealing conditions of the piston and the guide sleeve are improved by increasing the guide length of the piston appropriately, and the correctness of the improved scheme is verified by the way of simulation, that is, it can effectively suppress the vibration of the third piston. Vibration occurs during retraction. Some improvement suggestions are provided for vibration reduction of multi-stage hydraulic cylinder.

Effect of Internal Clearance on Buckling of Multistage Hydraulic Cylinder

Multistage cylinders are generally used to lift and tilt heavy loads under controlled speed. In defence applications multistage cylinders are used in missile tilt platform and antenna mast. Earth moving equipment’s such as tippers, dumpers, cranes and compactors uses multistage cylinders for operations. In the present work multistage hydraulic cylinder (telescopic cylinder) with three stage has been analysed using strain energy method and verified with finite element analysis. The research work investigates the effect of internal clearances which reduces the critical buckling load of hydraulic cylinders. The results are validated by buckling load test. The clearances between the tube to piston guides, gland guide to piston rod, clearances due to tube expansion under pressure, initial curvature in the tube, eccentricity of cylinder components and tube ovality are considered in the buckling load test. Describes the comparative study of buckling load tests of three stage hydraulic cylinders having fixed free and hinged mounting with five different internal clearances.<br /><br />

Mathematical modelling and backstepping adaptive sliding mode control for multi-stage hydraulic cylinder

Multi-stage hydraulic cylinder is widely used in large scale erecting devices. It can provide longer stroke from an initial package than single stage cylinder. It is divided into telescopic type and synchronous type. However, its structure is complicated. In order to get the characteristics of multi-stage hydraulic cylinder, motion model was established based on node chamber method. The LuGre friction model was improved considering the lubricant film. The contact force model was optimised using the equivalent damping model of the hysteresis factor. Simulations of erection process driven by telescopic and synchronous hydraulic cylinder were completed. Backstepping adaptive sliding mode controller was designed for multi-stage hydraulic cylinder. The proposed controller has a better performance compared to PID controller and ordinary sliding mode controller. The chattering has been reduced by using the saturation function instead of the sign function.

Mathematical modelling and backstepping adaptive sliding mode control for multi-stage hydraulic cylinder

Mathematical modelling and backstepping adaptive sliding mode control for multi-stage hydraulic cylinder

The coupling effects of the missile launcher and the ground in vehicle-mounted missile erecting

In order to study the coupling effect of the equipment and the launching site during the erecting process of the vehicle missile system, the lumped parameter model of the multi-stage hydraulic cylinder is deduced, the flexible multi-body dynamic model is established in ADAMS, and the normal and tangential coupling forces in the coupling relationship are derived. The coupling calculation model of the weapon system and the launching site is established in the co-simulation of the ADAMS and MATLAB/Simulink. The results show that the vertical slip of the launching platform is much greater than longitudinal and lateral ones. The erection angles of the cylinders at all levels when they begin to extend are 0°, 22.16°, 43°, and 65.52°, respectively, of which the speeds are 50 mm/s or so, and there are little limit impacts between the cylinders. The thickness of the surface layer has greatest influence on the stability and security of the launching platform, followed by the thickness of the base layer as well as the elastic moduli of the surface layer and the base layer. The conclusion provides important theoretical basis for the selection of the unsupported launching site.

Design and optimization of a novel throttling-inside-piston multi-stage hydraulic cylinder

In order to improve the performance of multi-stage cylinder to achieve rapid and steady extension, a novel throttling-inside-piston multi-stage hydraulic cylinder is proposed without changing physical size and piston working strokes of the traditional sequential multi-stage hydraulic cylinder. Based on internal structure optimal design and basic size parameter calculation, the mathematical model of the proposed throttling-inside-piston multi-stage hydraulic cylinder is studied using multi-rigid-body and impact-recovery dynamic theory. Then, the diameters of the orifices within the pistons are optimized using constraint optimization technique. Comparative simulation results show that the new type of throttling-inside-piston multi-stage hydraulic cylinder can significantly enhance the rapidity and steadiness for the erecting system.

Development of the compensation method of pressure pulsation effect on the multi-stage hydraulic cylinder motion

An example of the hydraulic wrench application is a maintenance process, associated with the main circulation pump jack at a nuclear power plant. Mathematical model of the hydraulic drive with two coaxial hydraulic cylinders is investigated to solve the problem of uncontrolled changes in the hydraulic drive system characteristics. The mathematical model considers the parallel connection of discharge chambers, nonlinear flow from the one-piston pump, fluid compressibility, the friction force between the actuator components. The drive operation is investigated at a full rotation of the feed pump crank. The system includes a throttle on the drain line in order to overcome negative hydrodynamic processes. The characteristics of the drive are investigated, and the throttle characteristics are defined to overcome pulsation. The values of the throttle opening area are determined for each time point, at a constant speed of the drive. Obtained matrix values are regarded as a law, and the speed becomes a calculated value, used to verify the results. Calculations have confirmed the possibility of providing the drive rod velocity, which is close to constant. Further development of the results provides a synthesis of the law of the throttle closing changes. It will provide the technological feasibility for manufacturing and ensure linear, close to constant, effort, generated by the hydraulic drive.

Research on Dynamic Modelling and Simulation of Erection System of Mobile Equipment in Absolute Coordinates

This paper employed the theories of multibody system dynamics to analyze the multi-rigid-body model of erection system and build the general dynamic models in absolute coordinates. The impact theory of contact mechanics and nonlinear spring-damper force function were used to model the impact problems between rods of multi-stage hydraulic cylinder of erection system and educe the dynamic models of multi-rigid-body erection system with impact. An automatic violation correction method according to the step of integration time was given to solve the violation which is an incident problem in numerical integration of dynamic models in absolute coordinates. Simulation results show that these dynamic models are effective.

Design and Study of Heavy Tipper Multistage Hydraulic Cylinder Based on CAD/CAE

The hydraulic cylinder is an actuator of hydraulic lifting system in the heavy tipper, which also plays an important role in unloading. Aiming at the existing multistage hydraulic cylinder design method's insufficiency, the CAD/CAE technology is introduced into the domains of multistage hydraulic cylinder design. In this paper push-forwarding five-stage hydraulic cylinder is designed, and virtual assembly is established based on three-dimensional digital model using PRO/E sofeware. The multistage hydraulic cylinder's load-supporting characteristics are analyzed by ANSYS. The result of finite element analysis shows that the stress on the top front part of three down hydraulic cylinder is biggest, those on the trunnion and the cylinder's bottom are also bigger. It is also proved that the multistage hydraulic cylinder designed with CAD/CAE technology can satisfy the requirements of intensity, rigidity and supporting stability.