The Down-the-Hole (DTH) drill is a piece of mechanical equipment used for rock drilling prior to engineering blasting; it is primarily employed in sectors such as urban construction, railways, and highways for drilling anchor bolt holes and blast holes. Domestic production began in the 1950s, with independent R&D and design improvements achieved in the 1970s; the Xuanhua region of Hebei Province serves as the primary domestic manufacturing base [2]. These drills are categorized by power source (hydraulic, internal combustion, or electric) and application environment (underground or open-pit), while hole diameters are classified as light-duty (80–100 mm), medium-duty (130–180 mm), and heavy-duty (180–250 mm).
Its core structure consists of a drill rod, a button bit, and an impactor that operates at the bottom of the hole; it utilizes a two-rod connection system for drilling, with a rotary air-supply mechanism driving the rotation of the drilling tools and a lifting/pressure-regulation system enabling controlled-pressure drilling. Key features include high mechanical efficiency, a lightweight design (total weight under 500 kg), and anti-jamming protection. The rotary motor typically has a power output of 4 kW, and the drilling depth can reach 30 meters, making it suitable for medium-hard rock formations (f=8–16). Open-pit models are predominantly self-propelled; some hydraulic versions feature an integrated air compressor design and offer semi-automatic drill rod disassembly capabilities.
