Research Of Ultrahigh-Pressure And Large-Flow Cartridge Proportional Throttle

With the continuous development and progress of China's industry,die forging press has been more and more widely used in aviation,aerospace,shipping and other fields,and gradually developed to super-large tonnage.The ultrahigh-pressure and large-flow cartridge proportional throttle is the core component of large die forging presses.Its localization is of great significance to ensure industrial safety.In this thesis,the operational principles and performance characteristics of some existing high-pressure and large-flow cartridge throttle at home and abroad is analyzed.The principle that using high-frequency proportional valve as the pilot valve to realize the closed-loop control of the main spool displacement is proposed and an ultrahigh-pressure and large-flow cartridge proportional throttle is designed.Then the static simulation of valve spool,valve sleeve and piston under ultrahigh pressure is carried out.In this thesis,the mathematical model of the valve is established by analyzing the flow rate and force of the pilot valve and the main valve and the simulation model of the valve is established on AMESim software.The function and performance characteristics of the valve are verified through simulation analysis.Based on the simulation result,the structure of the valve is optimized and a 50-diameter ultra-high pressure proportional flow valve prototype with maximum working pressure of 70 MPa is prototyped.In this thesis,a digital controller based on STM32F4 high-performance chip is designed and a PID-based control program is written.The digital controller can be combined with computer measurement and control technology to realize communication between the controller and the host computer,thus realizing the on-line adjustment of control parameters.The hardware part of the digital controller mainly includes power conversion module,high-frequency response proportional valve driver module,high-frequency response proportional valve displacement closed-loop control module,sensor signal conditioning and sampling module,serial communication module,CAN communication module and security logic module,etc.The software part mainly includes the PID-based embedded control program and the upper computer program of online parameter adjustment and monitoring.In this thesis,the pressure-resistance test of the designed throttle is performed on an ultrahigh-pressure test bench with test pressure up to 105 MPa.Finally,the step response,frequency response and steady-state control characteristics of the valve are experimented on an independently designed ultrahigh-pressure test bench.The experimental results of step response show that the rise time and fall time of step response are 33ms and 30ms at no-load and 26ms and 53ms at 70 MPa.Frequency response experiments show that the amplitude and phase bandwidth of the valve are 15.6Hz and 11.5Hz respectively.The steady-state control experiment shows that the hysteresis,linearity and repetition accuracy of the displacement characteristic curve of the electric signal valve core are 0.62%,0.31%and 0.1%respectively.The test results show that the overall performance of the valve is good and all the indexes meet the design objectives.