| Pipeline sluice gate valves are widely used as truncated valves,which are mainly used to connect or cut off the medium in the pipeline,tha t is,fully open or fully closed.Because of its advantages of reliable sealing,small switching torque and easy operation,it is widely used in the opening and closing devices of medium transportation pipelines such as oil and natural gas.However,the co mmon problem with valves including slab gate valves is leakage,which is mainly caused by leakage of the valve stem dynamic seal structure.However,there are some researches on the dynamic sealing structure of the valve stem at home and abroad.Therefore,this paper takes the valve stem dynamic sealing structure of the Class 600(600 lb)p ipeline slab gate valve as the research object,from the sealing surface contact pressure mechanics modeling,the sealing structure life.It is predicted that systematic research is carried out on the optimization of sealing structure parameters.The major studying substance and summing-up in the article are as below.(1)The first part of the thesis is the contact pressure mechanics modeling of the sealing surface of the valve stem dynamic sealing structure.Using the relevant theory of elastic mechanics,the internal and external sealing surface contact pressure distribution model considering the factors such as the amount of contact surface clearance,structural size,friction coefficient and filler property of the initia l filling of the valve in the dynamic sealing structure of the valve stem is established;The valve stem dynamic sealing structure has a gap for the inner and outer sealing surfaces,a gap for the inner sealing surface,no gap for the outer sealing surface,a gap for the outer sealing surface,a gap for the inner sealing surface,and no inner gap for the inner and outer sealing surfaces.The analysis of the example is carried out.The finite element analysis of the axial compression process of the sealing m aterial of the valve stem dynamic sealing structure is carried out by ANSYSWORKBENCH software,and the contact pressure between the inner and outer sealing surfaces obtained by the theoretical mechanical model is compared to verify the model.The correctne ss and rationality,in addition to the four working conditions,the contact pressure of the inner ring sealing surface at the same height position is always smaller than the contact pressure of the outer ring sealing surface.(2)The second part of the thesis is the prediction of the seal life of the v alve stem dynamic seal structure.The maximum contact pressure of the inner ring sealing surface is equal to the medium pressure as the failure criterion.The ABAQUS software is used to simulate the attenuation trend of the maximum contact pressure of the sealing surface during the reciprocating motion of the valve stem dynamic sealin g structure.The sealing medium pressure is 600 lb(11 MPa)as an example.Firstly,when the axial compression of the gland is 7mm,the upper limit of the reciprocating number that the sealing structure can reach is 36 times,so that the predicted sealing life is 108 days,and the sealing life(reciprocating number)and pre-tightening force are obtained.The relationship curve is obtained by fitting the function eigenvalues of the two,and the goodness of fit.(3)The third part of the thesis is the optimization of the parameters of the valve stem dynamic seal structure.Since the pressure of the sealing medium of the valve under study is 11 MPa,the safety factor of 1.1 times is designed,that is,the pressure equivalent to the sealing medium is about 12 MPa.Therefore,based on the running time of the contact surface maximum contact pressure equal to 12 MPa,the ISIGHT software is used to optimize the design of the valve stem dynamic seal structure,and the parameter combination with long running time is obtained.Under the same operating conditions,the optimized structure has an 18% longer sealing life than the original structure. |
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