Research on Load Characteristics of PDC Bit Rock-Breaking Cutting with Vibration Suppression

PDC drill bits often encounter frequent impact loads when drilling through formations containing gravel, alternating soft and hard formations, and performing directional drilling under complex operating conditions. These impact loads can lead to abnormal fatigue failures, such as tooth cracking, delamination of composite sheet, falling out of the teeth and broken teeth, greatly reducing the drill bit's service life and drilling efficiency. The concept of flexible rock cutting technology refers to the use of damping elements to reduce cutting stiffness, thereby limiting the magnitude of impact loads encountered during the cutting process within a certain range. The aim is to mitigate the fatigue damage of the cutter and extend the service life of the drill bit. By conducting experiments on flexible cutting units on limestone, the influence of factors such as cutting depth, rake angle, and the combination of damping units on the damping effect of flexible units are analyzed. The results show that: The flexible cutting can reduce the peak cutting load by 20% to 35%. The damping effect of the flexible unit shows a positive correlation with the combination stiffness of the damping units and the rake angle. The optimal combination for damping elements is a series connection of two A-type disc springs, and the optimal rake angle is 15°.