抽油泵柱塞拉伤失效原因分析

Causes of drawing grooves in subsurface pump plunger.

在分析抽油泵柱塞失效特征的基础上， 推断出拉伤失效是砂粒在柱塞端部锥面和泵筒内表面之间产生自锁所致。通过建立砂粒自锁条件及实测长石砂岩、石英砂岩与泵筒镀铬层或氮化层的滑动摩擦系数值， 证实了对柱塞拉伤失效原因的推测是正确的。因此， 为避免砂粒产生自锁， 对于采用镀铬泵筒的抽油泵， 柱塞的锥面角θ值应大于或等于１７－５°； 对于３８ＣｒＭｏＡｌ 氮化泵筒， 柱塞的θ值则应大于或等于１６－５°。应选用与石英砂岩摩擦系数较小的材料制造抽油泵泵筒。

Based on an analysis of the characteristic of failure of subsurface pump plunger, it is deduced that the drawing grooves in the plunger is caused by the self locking of sand grains between the end cone of the plunger and inside surface of the barrel. The deduction is confirmed by establishing self locking conditions and determining the sliding friction coefficients between sand and chromium plating layer and between sand and nitrided surface. To avoid sand grain self locking, as for subsurface pump with chromium plated barrel, the conical angle of the plunger θ should be more than or equal to 17 5°; as for subsurface pump with nitrided barrel, θ should be more than or equal to 16 5°. In addition, proper material for the pump barrel should be selected.