Experimental Study on the Effects of Cutter Diameter and Back Rake Angle on Rotary Penetration Cutting

ABSTRACT: During the drilling of thin interbedded layers, polycrystalline diamond compact (PDC) cutters frequently experience transitions between rotary penetration and stable shearing. To investigate the rotary penetration cutting rock-breaking characteristics of PDC cutters, a single-cutter rotary penetration cutting experiment based on a vertical turret lathe test system was developed. The effects of cutter diameter and back rake angle on rotary penetration cutting were analyzed. The results showed that in constant depth of cut (DOC) tests, cutting forces fluctuated periodically, while in rotary penetration tests, axial and tangential forces increased linearly with DOC. Additionally, cutting forces exhibited stronger fluctuations as DOC increased, with greater force fluctuations observed in granite compared to sandstone. Axial and tangential forces increased with the cutter diameter, as a larger cutter diameter reduced arc curvature and made axial penetration more challenging. An increase in the back rake angle led to greater cutting forces and higher MSE, reducing the cutter's rock-breaking efficiency. These findings provide valuable insights into the optimization of the cutter diameter and the back rake angle in complex formations.