SMALL-SCALE SPINDLE FOR A SECTIONAL DOWNHOLE DRILLING MOTOR (VARIANTS)

摘要

A spindle comprises n regulating elements in the form of quick-release sets of vibration dampers mounted in an upper chamber on a shaft above and below axial thrust bearings such as to be capable of preliminarily mutually offsetting the estimated frequency of the free vibrations of a dynamically perturbed mass of a drilling assembly with a bit (ω_с) and an experimentally determined frequency of the perturbing force (ω_д) arising as the bit breaks up the well bottom, in such a way that the transmission ratio (К_п), which is equal to the ratio of the amplitude of the force transmitted by a vibration damper to axial slide bearings (Р_в) to the maximum amplitude of the dynamic perturbing load (Р_д) arising as the well bottom is broken up by the bit, is selected as less than unity. A dynamic amplification factor characterized by a sinusoidal dependence of the phase difference between the perturbing load (Р_д) and the estimated structural deformation (∑ⁿ_i=1e_i) of the vibration dampers is selected taking into consideration the rotational frequency of the bit and the hardness of a particular rock by selecting a vibration damper rigidity K_ж= Р · ∑ⁿ_i=1 e_i (where P is the permissible static axial load on the downhole motor, and e_i is the estimated structural deformation of the ith vibration damper), so that ω_сω_д. The result is an improvement in the operating performance of the spindle and of the drilling assembly as a whole.