| The triple eccentric butterfly valve is developed from the traditional midline butterfly valve and double eccentric butterfly valve,inheriting the advantages of small size,light weight,simple and reliable structure.At the same time,it has the advantages of small switching torque,long frictionless life,and can be used for high temperature,high pressure and low temperature working conditions with hard sealing pair.With the function of cutting off valve and regulating valve.It is widely used in oil and gas,metallurgy,chemical industry,electric power and other industries with higher requirements on valve performance.However,the current design of triple eccentric butterfly valve with high requirements for machining accuracy,manufacturing difficulties,low yield and uncertain sealing effect.In actual production,100%test with actuators are needed,which results in high test cost and long production cycle.Starting from the sealing principle of the sealing pair of triple eccentric butterfly valve,the specific pressure equation that the triple-eccentric butterfly valve needs to meet to form effective sealing is established.The mechanism of machining and assembling error is discussed,and the size and direction of the error are obtained.Then,based on the specific pressure requirement of sealing and the possible error analysis,mathematical modeling is used to analyze the possible dimensional deviation caused by the above error in the closed position of the valve.SolidWorks is used to simulate the closing trip of the valve and analyze the interference or leakage of the sealing pair caused by the above errors.According to the above analysis,improvement Suggestions are put forward from three aspects:machining process,tolerance zone distribution and structure.With an 8 inch Class 600 hard seal triple eccentric butterfly valve as an example,using finite element analysis software simulation analysis was carried out on the seal,the contrast before and after improvement of uniform stress distribution so as to determine whether specific pressure finally to proofing of the 8 inch triple eccentric butterfly valve,to improve the sealing pair respectively before and after opening and closing operation of functional testing,sealing performance and cycle life testing to verify the improvement effect.At present,most of the improvement Suggestions in this paper have been applied to mass production.Although the triple-eccentric products are still tested 100%at present,the one-time pass rate is significantly improved,effectively increasing the product yield,reducing the test cost,shortening the production cycle,and extending the service life. |
