超高压压裂泵泵头体自增强再处理研究

Research on Secondary Autofrettage Treatment of Head Body of Ultrahigh Pressure Fracturing Pump

自增强技术是提高超高压压裂泵泵头体寿命的有效方法。针对自增强处理形成的残余应力易出现松弛现象,开展了对泵头体再次自增强处理的研究。分析了初始自增强处理的最佳自增强压力的计算方法,得出了最佳压力值为637.7 MPa;并计算了泵头体在最佳自增强压力作用下的残余应力及工作应力分量值。确定了泵头体危险处沿内腔十字交叉孔面法线方向的应力分量对泵头体疲劳寿命的提高或降低起主导因素。根据法向残余压应力的衰减量,研究了泵头体再次自增强处理压力及残余压应力层深度变化的规律。结果表明：当泵头体内腔残余应力衰减量达到40%~45%范围内,需要进行再次自增强处理;且实施再次自增强处理所需的自增强压力应略高于或等于初始自增强处理时的最佳自增强压力。

The autofrettage technique has proven to be an effective way of increasing the service life of the pumping head body of ultrahigh pressure fracturing pump. Focusing on the residual stress relaxation of autofrettage treatment,the research was carries out on secondary autofrettage treatment of pump head body. The calculation method for determining the optimum autofrettage pressure for initial autofrettage treatment is developed through which the optimized pressure of is calculated to be 637. 7 MPa. Also,the residual stress and working stress component of pump head body is calculated and analyzed which demonstrates that the stress component at the dangerous position along the normal direction of cross-hole plane has a great influence on fatigue life of pump head body. By analyzing the attenuation of normal direction residual compressive stress,the change rule of autofrettage pressure and depth of residual stress in secondary autofrettage treatment is studied. Result shows that when the attenuation of residual stress reaches 40% to 45%,the pump head body needs secondary autofrettage treatment,and the secondary autofrettage treatment pressure should slightly larger than or equal to the optimum autofrettage pressure of initial autofrettage treatment.