Research On Pneumatic Measurement Technology For Working Edge Quality Of Valve Sleeve Inner Annular Groove

Spool valve is the core component of large flow electro-hydraulic servo valve,its role is to precisely control over-flow through its throttling area change,and the working edge quality of the throttling orifice of valve sleeve directly affects the size of its throttling area,therefore,the working edge quality is particularly important.Since the working edge possess high processing accuracy,is easy to damage and located inside the valve sleeve and has other features,this thesis will use methods of pneumatic measurement to measure its processing quality,with non-contact,no pollution and high precision.Through the in-depth study of the edge quality evaluation standards and the status quo of their measurement methods,as well as the difference between the machining methods of the valve sleeve inner annular groove working edge and the ordinary valve sleeve and valve core working edge,the forming process and topography characteristics of the working edge of the annular groove in the valve sleeve are studied and the edge quality evaluation criteria are determined—edge beat on ends,edge equivalent fillet and edge verticality;according to the evaluation standard sub-item definitions,the measurement method of edge beat on ends—pneumatic narrow slit scanning method and the measurement method of edge equivalent fillet—pneumatic axial displacement pressure curve fitting method is determined.The edge verticality is defined according to the concept of edge beat on ends,and the edge verticality's algorithm is deduced based on value of the edge beat on ends.According to the definitions of the edge quality evaluation criteria,their influence functions on the opening size are established respectively,and their influences on the opening size are calculated based on MATLAB;the measurement resolution is defined,and the measurement parameters are initially selected according to it;pneumatic measurement model is established based on Solid Works and utilizing Fluent to carry on the simulation analysis to its inner flow field pressure,the flow velocity as well as the measurement resolution,finally determines the measurement parameter on this basis.Using computer technology to design measurement program of the edge quality;according to the influencing factors of pneumatic measurement,having designed gas path of the air supply and measurement;according to the measuring principle of the edge quality standard and from the perspective of measuring accuracy,the measuring device of edge beat on ends and edge equivalent fillet are designed;complete design of control system hardware and measuring circuit's construction.The calibration of the measuring circuit and the pressure sensor is completed;according to the measuring principle of the working edge's equivalent fillet,it's measured and repeated measuring error and measuring accuracy are analyzed;according to the measurement principle of the edge beat on ends,the measurement system is calibrated,the value of the edge beat on ends is measuring and analyzes its measuring accuracy,finally,the value of the edge verticality is calculated according to the edge verticality algorithm.