Analysis of the influence of feed and lateral force on productivity and hand-arm vibration in interaction with drill bit wear and concrete strength

Abstract

The productivity and vibration are important aspects of the ergonomic evaluation of hammer drills and are influenced by drill bit wear and the feed force. In addition, the user applies a lateral force. The influence of the lateral forces in interaction with the drill bit wear on productivity and hand arm vibration (HAV) has not been investigated yet. In this study, first, the influence of the feed and lateral force on drill bit wear was investigated and subsequently how this wear interacts with the user forces to change hammer drill vibration and the rate of penetration. Furthermore, the concrete strength and the drill bit manufacturers were varied. The experiment was performed on a robot-based test rig with a total of 4800 boreholes. The rate of penetration, the hammer drill vibrations, and the wear of the drill bit were measured. It could be shown that the lateral force has a strong effect on the helix diameter wear (p < .001). Furthermore, the feed and lateral force each had an influence on the hammer drill vibration (each p < .001) and on the rate of penetration (each p < .001). The lateral force in interaction with the drill bit wear changed the vibration at the main handle. Further, it could be shown that the wear pattern varies depending on the concrete strength and drill bit manufacturer. These findings help manufacturers in developing reliable and ergonomic products and for class societies in designing standards for HAV.