A Novel Oscillating Orientation Device of DTH Hammer for Hard Rock Stratum Non-Dig Drilling

Abstract

Non-dig piping in hard rock stratum is a popular research topic in the world, and the bottleneck of the technology is how to control down the hole (DTH) hammer's drilling trace without hammer jamming. Based on DTH hammer's rock stratum drilling principle and study of modern orientation technologies in the world, this paper presents a novel Oscillating Orientation Device (OOD) applied on DTH Hammer which can control DTH drilling direction and avoid hammer jamming. The oscillating orientation device locates between drilling rod and DTH hammer which has unbalanced or incline drill head. DTH hammer and oscillating orientation device are both connected to the same compressed air resource. The oscillating orientation device will produce a strong small angle oscillation movement when compressed air is input. During straight hole drilling process, because drilling rod goes straight down without rotation, the orientation device attached to the rod will produce a straight line oscillating movement. This movement will make the DTH hammer that is attached to the orientation device doing the same straight line oscillating movement too. The DTH hammer's straight line small angle oscillating movement will keep drilling hole straight and also resolve the jamming problem that normally presents in rock stratum drilling. Compared with traditional DTH hammer structure, the presented design only adds an extra oscillating orientation device and applies unbalance or inclined drill head without any inside structure change of DTH hammer. So the presented design dramatically reduces rock stratum drilling cost by avoiding jamming problems without any loss of the advantages of traditional DTH hammer like stability, long service life etc. In the paper, oscillating orientation device structure and theoretical working principle analysis based on the structure are presented. The oscillating orientation device working principle is: inside a sealed chamber, through controlling of intake and exhaust ports, high pressure air drives two symmetrical blades oscillating in a small circular sector area. Then, this movement creates the same movement of DTH hammer. According to experiment results, this novel oscillating orientation device is an economic and simple solution for resolving jamming problem of non-dig rock stratum drilling.