Performance Investigation of a Low-Speed High Torque Hydromotor Drive System Used in Blast Hole Drill Machine Under Varying Load Conditions

In this article, a performance investigation of a low-speed high torque hydromotor drive system used in blast hole drilling machine is carried out for varying load conditions. Blast hole drill machines are widely used in drilling operations in open-pit mines to drill hole in rocks. During such operation, the varying strength of rocks results in variable load on hydromotor, which decreases its speed and it may lead to fluctuations in speed as well as torque. A high torque low-speed hydromotor is used to fulfill the requirement of operation, which has lower volumetric efficiency than its counterpart. As a result, such hydromotors have more leakage losses with an increase in the load on it. Therefore, a constant speed of the drill bit of said machine is needed for smooth operation. In the present work, a PI controller is used to vary the pump displacement that manipulates the supply flow to the hydromotor in order to maintain a constant drive speed irrespective of load. In this respect, a Simulink model of the drive is developed, and a test rig is fabricated to validate the system responses. The test rig consists of a loading unit that replicates similar varying load conditions on hydromotor as it experiences with the variation in the strength of the drilled rock. The obtained results indicate an improved performance of the hydromotor drive used in the blast hole drilling operations by implementing the said controller.