The Analysis Of Composite Buffer Structure Of Hydraulic Cylinder And Buffering Process

Hydraulic drive is a very important way, which has been widely used in the engineering machinery, metallurgical machinery, plastics machinery, automobile and other industries. The hydraulic cylinder is the main hydraulic actuator, however, when hydraulic cylinder with heavy parts moves in a high speed, parts have great kinetic energy, because of the inertia force and liquid pressure, so that, the serious block problem happens when the piston reaches the (its) end. It has not only suffered from impact and vibration, but also damages the hydraulic cylinder and other components of the hydraulic system. So it is very important to how to avoid the impact and vibration, strong noise, improve the working performance of the system when the piston moves to the end of stroke.This paper mainly researches on the buffering mechanism of different inside-cylinder buffering structures, especially the buffering processes of column-shape, taper-shape, inclined shape, constant orifice and parabola-shape are analyzed in detail. The analysis show:constant orifice and column-shape have great pressure at the early stage of buffering, then pressure quickly slows down, which is suitable for lower speed and lighter load; the early pressure changing trend of taper-shape is smooth, the late has great pressure jump; inclined shape has the lower peak pressure and better buffer performance, and the pressure is gradual process; parabola-shape is buffer device of constant deceleration, but has acceleration impact larger at the first and end buffering stage. Combined with the advantages of various structures, the composite structure is designed and the buffering processes are divided with three-stages: first, when the piston just entering the buffer stage with taper-shape, buffering pressure jump is lower, and plays a guiding role; second, the inclined shape is considered as the main structure of buffering process, has the lower pressure peak, high efficiency of kinetic energy dissipation in little time; third, when speed is small, column-shape is used at the end of buffering stage, meanwhile constant orifice always exists in the whole process of parallel. By simulation to the buffering process with MATLAB software, the structural parameters were optimized. The results show that the optimized buffer features higher efficiency, lower buffer peak value and better buffer performance and the buffering time is short, which meet the buffering demand of hydraulic cylinder.The composite buffer structure only applies to fixed condition, in the practical application, the best buffering characteristic associate with structural parameter itself, also with the real impact load and the choice of initial velocity. So this paper focuses on the use of COM components to connect VB with MATLAB, so that the powerful function of MATLAB in image processing and numerical computation and the advantages of VB in the interface design can be integrated. Just input some basic parameters of the working condition of cylinder, relationship graphic between speed and stroke, relationship graphic between acceleration and stroke will be provided. Thus the design of inside-cylinder cushioning structure is achieved in little time. In the end, the case is provided to verify the use value of this software.The composite buffer structure features non-hard impact and low soft impact in the buffering process. The innovation of this structure lies in:1) the device has the advantages of compact structure, easy processing and the buffer effect is good;2) the flow cross-sectional area decreases continuously with increasing buffering stroke, and the buffering process is smooth and low impact;3) combined mathematical calculation and graphic expression ability of MATLAB software, with the friendly visual interface of VB, it is very easy to achieve the rapid design of the buffering process.