| Casting process of injection system is divided into three processes which contain slow injection, fast injection and pressure holding, the shift speed from slow injection to fast injection must be as fast as possible. Water hydraulic valve is used to control speed in casting machine, changing flow area of valve can satisfy the speed change, so gradient of valve area growth must rise at the point of injection process shifting from slow to fast. As we know, cone valve has good sealing performance and spool valve with throttling grooves can meet demand of area change at valve port, so a kind of valve combined cone valve and spool valve with U & rectangular throttling grooves was used in this thesis. Hydraulic flow force and cavitations phenomenon take place when water flow across valve port, hydraulic flow force becomes bigger when the flow rate is bigger, which affects performance of valve control, cavitations phenomenon does harm to valve life and performance, so it is necessary to do some research on hydraulic flow force and cavitations phenomenon about the valve of this thesis.Firstly, the paper analyzed working condition of the casting system and designed the structure of the valve, which was a valve combined cone valve and spooling valve with U & rectangular throttling grooves, at the same time, the model was established, mesh was finished and boundary conditions ware specified.Secondly, simulation analysis method of hydraulic flow force and cavitations ware offered, as for hydraulic flow force, a method of calculating steady flow force was put forward based on choosing control volume; furthermore, area calculating method of valve port of this paper was done.Thirdly, pressure valve allocated in the middle plane and vapor phase volume fraction ware offered as the evaluating criteria for occurrence and severity of cavitations. Furthermore, a kind of specified structure was chosen between some ones by mean of evaluating characteristics of cavitations and flow steady force.Lastly, the paper did some work to analyze relationship between structure parameters and characteristics of cavitations and flow steady force, validated value accuracy of theoretical calculating method for steady flow force coMPared with that from simulation directly, coMPared results whether considering cavitations model when analyzed steady flow force. |
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