| Gas-liquid combined hydraulic impact mechanism has been widely used in mining,construction engineering and other fields.Compared with other types of impact mechanism,it provides kinetic energy by combining nitrogen chamber and system oil pressure.At present,the hydraulic impact mechanism with high impact energy occupies the absolute advantage in the market,and the improvement and optimization of its performance become the focus of attention.The hydraulic impact mechanism is characterized by high impact energy,reciprocating motion and long working time in the front line.Therefore,some problems inher ent in the hydraulic impact mechanism are exposed,including the large internal leakage of the piston and the drawing cylinder,resulting in the low efficiency of the hydraulic impact mechanism.This paper takes a certain type of gas and liquid combination type hydraulic impact mechanism as the research object.The effect of piston surface equalizing groove on relieving internal leakage and hydraulic clamping was studied.The factors influencing leakage and clamping force of hydraulic impact mechanism are analyzed,including structural parameters(length of sealing section,height of clearance,number of pressure equalizing groove,ratio of width to depth,taper)and working parameters(differential pressure between the two ends of sealing section).Combined with the data processing methods of numerical simulation experiment and orthogonal experiment,the following work is mainly done:1.Firstly,the current problems of hydraulic impact mechanism are summarized,and the development direction of hydraulic impact mechanism in the future is summarized.The working principle of the hydraulic impact mechanism is analyzed,and the mathematical models of impact piston,nitrogen chamber,accumulator and impact energy are established respectively in combination with AMESim of the system simulation software,and the AMESim simulation model of the system was built.From the point of view of the system,the working state of the hydraulic impact mechanism is understood,the relation curve of piston displacement and velocity with time is analyzed.At the same time,the pressure variation of each chamber in the hydraulic system is obtained,which provides a parameter basis for analyzing the weight of hydraulic impact mechanism.2.The leakage and clamping mechanism of the hydraulic impact mechanism are analyzed.Based on the crack leakage mechanism of the parallel plate,the relationship between the differential pressure flow and shear flow and the structure of the hydraulic impact mechanism is derived.At the same time,the calculating for mula of the leakage of eccentric annular crack is obtained.The causes of the clamping force are explained from the two aspects of the piston's clockwise cone and its inverse cone.3.Based on the field synergy principle,the field synergy analysis is carried out for rectangular slots with different width-depth ratios.By analyzing the synergistic relationship between velocity field and velocity gradient field inside the pressure equalizing tank,the magnitude distribution of the field synergistic Angle inside t he pressure equalizing tank is obtained.An in-depth explanation of the mechanical energy dissipation inside the equalizing tank is helpful to analyze the root cause of leakage of hydraulic impact mechanism.4.Based on numerical simulation experiment analysis,combined with orthogonal test method.The factors affecting leakage and clamping force of hydraulic impact mechanism are analyzed,and the main factors are selected for orthogonal test.At the same time,the dimensionless analysis of the influencing factor s was carried out to compare the weight of leakage and clamping force in the influencing factors.The weight order influencing the leakage amount is: clearance height > piston eccentricity > pressure equalizer tank width and depth than the pressure differe nce between the two ends of > seal > seal length > pressure equalizer tank number.The order of weight influencing the clamping force is: piston surface taper > number of equalizing pressure slots > piston eccentricity > ratio of width to depth of equalizin g pressure slots.At the same time,the coupling analysis of the factors affecting the clamping of hydraulic impact mechanism is made.5.Comprehensive analysis of leakage amount and clamping force of hydraulic impact mechanism.The maximum and minimum parameters of the clamping force are analyzed by taking the clearance height which has the largest influence on the leakage weight as a variable. |
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