With the development of the industrial technology,the general soft seal butterfly valve has not been satisfied with the demand in the industry, so the metal seal butterfly vavle has been developed.The tri-eccentric butterfly vavle is the most advanced during the butterfly valve development and evolvement.But,at present, the tri-eccentric butterfly valve has not been studied thoroughly at home,and has not been formed a perfect theory system, brought about the limitation of the tri-eccentric butte...