Research On Ultra-High Pressure Abrasive Water Jet Cutting System And Its Key Technologies

The demand of cutting market for new materials with high-strength and high-hardness could be met by abrasive water jet of ultra-high pressure,which has led companies to invest heavily in research and development in this field.At present,the main market for abrasive water jet cutting system and spare parts is occupyied by Europe and the United States accounting for more than 85% market share.Relatively,the key components for abrasive water jet in domestic market rely on imports,such as intensifier pump and nozzles.Teoretical research is also lagging behind in relative field.Therefore,from the engineering practice,this paper dose further studies on abrasive jet cutting system and its relative key technical and theoretical issues in pressure pulsation,ultra-high pressure sealing and nozzle mixing cavity structure.The main research contents are as follows:By the analysis on the pressure and flow fluctuation characteristics of the ultra-high pressure system,the time-control technology in multiple fusion of stable pressure and flow is established to further reduce the pressure and flow fluctuation.According to the working principle of the ultra-high pressure intensifier system,the mathematical equations of the two-group booster cylinder system is established.In order to determine the influence of timing control on parameters such as flow rate and pressure,the simulation technology is used to analyze and evaluate the influence of the phase difference of the plunger movement,the volume of the accumulator and the timing control of the dual pump time-control technology.By selecting appropriate component parameters and control timing of the two-group ultra-high intensifier cylinder system,the pressure and flow fluctuation can be controlled precisely by single or dual nozzle.The ultra-high pressure self-compensating variable clearance seal of the cylindrical plunger structure is designed by using the clearance sealing principle.The dynamic seal is a variable clearance seal that relies on metal-elasticity.In order to solve the problems of large friction and low life of the contact seal,and to solve the problem that the leakage of the constant clearance seal increases with the increase of the working pressure,the end of the high pressure plunger is designed as a cylindrical structure.The variable clearance seal is achieved between the plunger and the bushing by adjusted the elastic deformation.The radial deformation of the cavity is calculated by analyzing the deformation theory of the cylindrical plunger.Under different working pressures and different initial clearances,the pressure distribution,clearance distribution and leakage are iteratively calculated.The cylindrical plunger clearance deformation and the minimum width of the clearance seal are all increased as the increase of the working pressure.The research results can solve the problem of ultra-high pressure sealing.On the basis of analyzing the cylindrical plunger variable clearance seal,the reciprocating plunger is guided and supported by the truncated cone valve feedback throttle static pressure technology.Static pressure oil chambers are arranged in the guide sleeve of both ends of the plunger,and the plunger is supported by the pressure oil input from outside.The intensifier plunger can be automatically centered in the ultra-high pressure cylinder.Under the condition of keeping the supporting clearance constant,the index of the oil inlet variable of the truncated spool spool throttle is equal to the index of the oil displacement of the bearing oil chamber.It can improve the feedback response characteristics and stability of the system against partial load.The mechanism of abrasive mixing under high-speed jet is studied,and the influence of different mixing cavity structure on abrasive jet parameters is analyzed.The velocity distribution of each node in the abrasive water-jet nozzle is calculated by numerical simulation.The mixing and acceleration characteristics of abrasive particles with one-way and circumferential sand feeding are analyzed.The energy utilization of different sand feeding modes in the cutting head mixing chamber is compared.The pressure stability and the nozzle abrasion are analyzed through the experimental methods.A series of cutting experiments were carried out by setting different parameters,such as jet hydraulic pressure,cutting head moving speed,abrasive flow rate,workpiece thickness and workpiece strength.The prediction model for cutting depth of the two-way sanding abrasive water jet is established.