Ever Wondered How DTH Drill Rigs Revolutionize Rock Drilling?

The down-the-hole (DTH) drill rig is commonly used in rock anchoring, bolt-hole drilling, blasting, grouting, and other drilling operations in urban construction, railways, highways, rivers, and hydropower projects. Today, let's delve into its structure, operating principles, and installation precautions.

Operating Principle of DTH Drill Rig

In essence, the operating principle of a DTH drill rig mirrors that of a conventional impact rotary pneumatic rock drill. The pneumatic rock drill combines impact and rotary mechanisms, transmitting impact force through the drill rods to the drill bit. However, the DTH drill rig separates the impact mechanism (impactor) and immerses it into the borehole. Regardless of the borehole's depth, the drill bit is directly mounted on the impactor, eliminating the need to transfer impact energy through the drill rods, thus minimizing energy loss. The DTH drill rig derives its name from the impactor's submersion into the borehole.

Structure of Large Open-Pit DTH Drill Rig

Drill Frame: The drill frame serves as the guide for the sliding of the rotating device and the lifting of drilling tools.

Sliding Frame: Constructed from welded steel plates, the sliding frame connects and supports the drill frame.

Rotating Device: Comprising hydraulic motors, the main spindle mechanism, button bits, sliding plates, and a central air supply system. The chain of the propulsion mechanism is fixed on the sliding plate through pin axles and a spring-damping mechanism.

Propulsion Mechanism: Consisting of a propulsion hydraulic motor, sprocket groups, chains, and buffer springs.

Rod Handler: Comprising upper and lower rod handlers, rod-clamping cylinders, and unloading cylinders.

Dust Removal Device: Divided into dry, wet, hybrid, and foam dust removal systems.

Traverse Mechanism: Comprising traverse frames, hydraulic motors, multi-stage planetary reducers, tracks, drive wheels, idler wheels, and tensioning devices.

Framework: Compressors, dust removal systems, oil tank pumps, valve groups, and the operator's cabin are installed on the framework.

Rotating Mechanism of Rig Body: Comprising a rotating motor, brake, reduction device, pinion gear, and rotary support.

Drill Frame Swing Mechanism: Comprising swing cylinders, hinge axles, and hinge seats, allowing the drill frame to swing left and right, adjusting the drilling angle.

Air Pressure System and Impactor: Equipped with a screw-type air compressor, providing compressed air for the high-pressure impactor and a laminar dust removal system's blowing dust system.

Installation and Preparation of DTH Drill Rig

• Preparing the Drilling Chamber: The chamber's dimensions should align with the drilling method. For horizontal holes, the chamber height is 2.6-2.8 meters, while upward, downward, or inclined holes have a width of 2.5 meters and a height of 2.8-3 meters.

• Laying Water and Air Pipelines, Lighting Circuits, etc., close to the working face for future use.

• Securely Install Pillars According to Hole Design Requirements: The upper and lower ends of the pillars should be padded with wooden boards. Horizontal axes and clamps should be installed at specific heights and directions on the pillars. The machine should be lifted using a manual winch, fixed at the required angle on the pillar, and then the drilling direction adjusted.

Routine Maintenance of DTH Drill Rig

Pre-Operation Checks: Before commencing work, carefully inspect air and water pipelines for firm connections and any signs of leakage. Check if the oil injector is filled with oil, and ensure screws, nuts, joints, and columns are securely in place.

When the DTH drill rig stops working: Stop the machine and release the oil in the sump while still warm. Clean the sump and filter screen with diesel cleaning agents. Change the machine oil and filter every 250 hours.