Research on working principle and cross-track cutting characteristic of the axis-tilted rock-breaking tool

Abstract

Concentric-track cutting method of a conventional polycrystalline diamond compact bit makes the bit suffer from inadequate rock-penetrating capacity and severely hinders the improvement of rock-breaking efficiency. Nevertheless, cross-track cutting method is already proved to be an effective way to improve the penetrating ability of the bit. Accordingly, a novel rock-breaking tool with tilted rotating axis is put forward in this article. In this research, first, the structural characteristics of the rock-breaking tool with tilted rotating axis are introduced in detail, relation equations of key geometric parameters of the bit are established, and coordinates of the feature points of the cutters are represented. Second, tracks and motion tendency of the cutters in different areas, as well as the bottom-hole coverage pattern, are respectively analyzed, and the influences of different factors on cutter motion are compared. Third, corresponding indoor experiment is conducted to research the influences of revolution/rotation ratio and axis-tilt angle on drilling efficiency, and the rock particles are compared to reveal the rock-breaking mechanism of the tool. This research is intended to provide basic theoretical support for the engineering application of the tool and is of certain referential significance to improving the rock-breaking efficiency in formations of poor drillability.