Investigation of Rod Pump Wear During Changes in Load Dynamics and the Design Trajectory of the Rod

Abstract

The article is the first to investigate the mechanism of wear of the oil production pump couplings as a result of a violation of the design trajectory of kinematic connections from a given axis of symmetry. The critical values of the acting moments and stresses in case of inefficient load redistribution across the cylinder at different positions of the worn plunger are substantiated and presented. Using the Cauchy parameter model, an indirect assessment of the effect of dynamic loads on the actual capacity of the pumping unit is given, taking into account the wear of kinematic connections. It was possible to improve the Lame equation by describing the law of reciprocating motion of a plunger with uneven wear, as the equation of longitudinal elastic vibrations of the rod, taking into account the distributed specific external load acting on the rods, distorting the design trajectory of the kinematic pairs. The process of interaction of the elements of the rod-plunger-cylinder system of an oil production pump with uneven axial moments is investigated. The authors proposed a new term for the deviation of the design trajectory (Δλ) of the rod and plunger relative to the axis of symmetry of the cylinder. The mathematical model of pump capacity (Qa) and its resource life has been improved when changing the maximum allowable gap δt = f(i) in the plunger-cylinder system of a rod pump and leaks (qt) due to violations of the design trajectory (ΔλΣ) of kinematic pairs due to uneven distribution of dynamic loads. A dynamogram has been developed to determine the dependence of the load distribution on the movement of a worn plunger during basic contact stress cycles.