Development On High Flow And Fast Throttling Proportional Valve

In order to brake the speed of cylinder rapidly to reduce the pressure casting fash in the die casting,this topic developed a kind of proportional valve.This valve used three stages of actuations,the main stage used the structure of cartridge valve,the pilot valve integrated the characteristics of high speed switch valve and proportional valve: when the ma-in spool didn't achieve the target position,it is drived fastly by the switch valve of the pilot.When the main spool achieved the target position, it followed the proportional lever through the followup relations between them and reached the target position steadily without overshoot.The proportion lever's position was adjusted by a prop-ortional pressure relief valve.Optimum design of the valve was carri-ed on using the simulational methods,such as Fluent,AMESim.The test result indicated that the high flow and fast throttling proportional valve could realize reducing the speed of high speed cylinder and avoiding pressure casting fash effectively.Consequently,it was able to enhance the casting speed under the same locking force of the die, this had the important meaning to the improvement of casting craft and utilixation of the casting equipment.In the first chapter of the paper,the typical pressure casting craft's was introduced briefly,and the reason and harm of the pressure casting fash was also analyzed,what's more,several method of eliminating the fash and their characteristics was summarized. After introducing the existed control system of die-casting machine,the significance and research value of this topic was more clear.Finally,the research aim and the main research content of this topic were both proposed,it's usefull for the later research work.In the second chapter,the scheme of the high flow and fast throttling proportional valve is describled,the optimum design of the primary structure parameter was carried on. It also taked the examination on the flow channel that affected the valve's perfor-mance,lastly, the key question of the design and the technical difficulty were proposed in order to lead the direction for the next optimization.In the third chapter,the structure and the scheme of the pilot valve were describl-ed,also the key question of the design was proposed. According to the request of the valve's dynamic characteristics, optimization design was carried on.Through the research of AMESim simulation,it discovered that the movement of main spool had overshoot when it moved to the goal throttle position,in order to solve the problem,the measurement of taking the variable gain orifice valve was applied,this would realize non-overshoot position control of the main spool and also have no effect on the rapidity of the movement of the main spool.The the design of the test platform and experimental study of the high flow and fast throttling proportional valve were both included in the fourth chapter.In the design proposal of the test platform,the method of using accumulator to provide the instantaneous high flow and the method of using noload hydraulic cylinder to measure the high flow were applied,it solved the difficulty of conventional method to satisfy the request of high flow experiment.The experiment of the valve indicated that speed peak appeared in the section of the cylinder's fast throttling,the primary cause was:the movement of main spool had overshoot when it moved to the goal throttle position,in ord-er to solve the problem,the measurement of taking the variable gain orifice valve is applied.In the fifth chapter,the comprehensive summary to this topic was made,and also the question in this topic research work and the research work's key point were both pointed out.