Domestic spherical rubber core have bad sealing property and low service life,which can't meet the demand of domestic drilling operation.The spherical rubber core of FH35-35 blowout preventer was taken as the research object,and the three dimensional finite element model of the rubber core sealing the drill pipe were established.The result showed that the stress concentration at the upper and bottom of the rubber core was the main reason that caused rubber core damaged;sealing length was gradually increased while the piston's displacement increased,but the sealing pressure had a lag phase to growth,the piston's stroke should not be less than 166 mm.When the column height of rubber core was 210-220 mm,the sealing pressure and sealing length was the best,and the sealing area had low stress,which can improve the service life of rubber core.%国产球形胶芯的密封性能差、使用寿命低,不能满足钻井作业需求.以FH35-35型球形防喷器胶芯为研究对象,建立胶芯密封钻杆的三维有限元模型.分析结果表明:胶芯上部及底部出现应力集中,是导致胶芯发生破坏的主要原因；密封长度随活塞位移增加而逐步增长,但密封压力的增长却有一段停滞期,指出活塞最小行程不宜低于166 mm;胶芯内圆柱高度在210～220 mm时,密封压力、密封长度最佳,且密封区域的应力低,有助于提高胶芯的使用寿命.
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