A method for calculating the values of forces acting on the roller-cone bit teeth

Abstract

The results of an analytical study of the loading of elements of a roller-cone bit cutting structure are given. For an analytical assessment of the magnitude of the forces acting on the bit teeth, the bit is fixed in a static state in a string of drill pipes or a drill assembly, with each roller cone resting on a flat bottom with one tooth on which axial force acts from the bottom. For the disclosure of static indefinability, the equations of deformation of the system are compiled. Calculation of the loads acting on the cone rows was carried out in relation to the cutting structure layout for the Sh215,9K-PV bit cones. To determine the values of the forces acting on the teeth, the dependencies between the magnitude of the load acting on the roller cone and the vertical movement of this tooth, previously obtained analytically and experimentally, were used. It is established that the maximum load acts on the rows located in the middle part of the bit radius. The calculation results are confirmed experimentally. The results obtained can be used to optimize the design of the cutting structures and supports of roller-cone bits at the design stage.