Improved Design of Cluster-type Reverse Circulation DTH Hammer for Reaming

To solve the new problem of cluster-type reverse circulation DTH hammer in original chambering during drilling process, considering comprehensively the execution conditions including ZMK5530TZJ60(A) truck rig, φ178/113 mm double-wall drill and large diameter test drilling, we improve the cluster-type reverse circulation DTH hammer in new chambering. In the process of field test, a good result of reverse circulation and deslagging was achieved; the highest penetration rate was 6 m/h, and the average penetration rate was 3.41 m/h which increased more than 0.6 times compared to cluster-type reverse circulation DTH hammer in original chambering under the same condition. Field tests show that improved structure was reasonable and it can be extended to the construction of large-diameter engineering hole.