Experimental study on motion and mechanical characteristics of the vertical wheel in the rock-breaking process

Polycrystalline diamond compact (PDC) drill bit often performs with low ROP, short service life and poor stability under complicated and difficult to drill formations. Therefore, a vertical wheel PDC bit is pro-posed, which is a new drill bit technology applying an integrated unit combining the tooth wheel and the rotary shaft thereof. Besides, the experiments on motion and mechanical characteristics of the vertical wheel under the conditions of tooth shape and number of teeth, normal deflection angle of the wheel, and different cutting depth were carried out using variable parameter experimental device, and the movement, force law, and crushing specific work of vertical wheel under different experimental con-ditions were obtained. The comparative experiments of PDC cutting rock breaking under the conditions of parallel cutting of PDC unit and pre-damage of the wheel were also carried out, and the cutting load of PDC teeth under pre-damage conditions is between 38.72% and 70.95% lower than that of parallel cutting was obtained. Finally, a comparative experiment of indoor drilling between vertical wheel PDC bit and conventional PDC bit was carried out. Results show than when drilling in gravel rock, under the same WOB, the torque response of vertical wheel PDC bit is equivalent to that of the PDC bit, while the ROP of vertical wheel PDC bit is 22.94%-53.33% higher than that of conventional PDC bit, and the three-dimensional acceleration of the vertical wheel PDC bit is 19.17%-76.23% of that of the PDC bit. The experimental results contribute to a better understanding of vertical wheels and provide technical support for their use in PDC bits.(c) 2022 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).