Optimizing Drilling Parameters: A Novel Cyclical Motor Control Concept to Adjust the Impact Energy Independently of the Frequency for Impact Mechanisms

Abstract

Hammer drilling is widely used to drill holes in hard materials. For high productivity, the impact mechanism generates impacts to remove the hard material to be drilled. The parameters of impact energy and impact frequency mainly influence drilling productivity. Further optimization requires more ways to influence the drilling parameters. Presently, however, the impact energy cannot be changed independently of the impact frequency. This paper investigates a new cyclical motor control concept to influence the impact energy independently of the impact frequency. The new control concept changes motor velocity in a highly frequent and cyclical manner as a function of the motor angle to adjust the impact energy by changing the timing of the impact mechanism. So far, this timing has only been adjusted by changing the impact frequency. An experimental study was carried out to measure the motor control concept's effect on the impact mechanism’s timing and impact energy. The new control concept allows for an independent variation of the impact energy and impact frequency. An automated drilling study revealed that this increases drilling productivity. By means of the new concept, impact energy and drilling productivity can be further optimized. It may also be applied to improve productivity of other impact systems, such as impact wrenches.