GLOBORX DTH Hammer Usage and Maintenance

1. Overview The high-pressure pneumatic hammer is a type of impact drilling tool. Unlike other drilling tools, it remains at the bottom of the hole during drilling, with the piston directly impacting the drill bit. Compressed air enters the hammer through the drill rod and is then expelled through the drill bit. The discharged exhaust air is used to clear debris. The hammer’s rotary motion is provided by the rotary head of the drilling rig, while the axial thrust is supplied by the rig's feed mechanism and transmitted to the hammer through the drill rod.

2. Structural Principle The DTH hammer consists of several key components: the piston, inner cylinder, gas distribution seat, check valve, and drill bit accessories, all housed within a long outer cylinder. The upper end of the outer cylinder is equipped with a joint head featuring a spanner mouth and connecting threads, while the lower end has a coupling sleeve with connecting threads. The coupling sleeve transmits the advancing force and rotary motion to the drill bit. The retaining ring controls the axial movement of the drill bit, while the check valve prevents debris from entering the hammer when the air supply is stopped. During drilling, the drill bit is pushed into the hammer and pressed against the coupling sleeve. The piston then impacts the drill bit to break rock. When the drill bit is lifted from the bottom of the hole, strong air is used to clear debris.

3. Usage and Operation Precautions

1. Ensure Reliable Lubrication The lubrication of the hammer is achieved through the oil injector on the drilling rig. Therefore, it is essential to ensure that the oil injector is fully filled with lubricating oil before the start of each shift, and there should still be remaining oil at the start of the next shift. Use 20# mechanical oil in summer and 5-10# mechanical oil in winter.

2. Before installing the hammer onto the drill rod, operate the exhaust valve to clear debris from the drill rod and check if there is lubricating oil in the drill rod. After connecting the hammer, inspect the drill bit spline for an oil film. If there is noticeably no oil or too much oil, adjust the oil injector system.

3. When starting the drilling process, operate the advance air valve to move the hammer forward while pressing it against the ground. At the same time, open the impact air valve to initiate the hammer’s impact operation. Be careful not to allow the hammer to rotate, as this will destabilize the drilling. Once a small pit is created and the drill stabilizes, open the rotary air valve to bring the hammer into normal operation.

4. During operation, regularly monitor the compressor’s RPM gauge and pressure gauge. If the rig’s RPM drops sharply and pressure increases, it indicates a problem with the drilling, such as wall collapse or a mud plug inside the hole. Immediate action should be taken to address the issue.

5. Throughout the drilling process, ensure the hole is free of rock debris. If necessary, perform a strong air blowout by lifting the hammer 150mm from the hole bottom. During this time, the hammer will stop impacting, and all compressed air will flow through the hammer’s central hole to expel debris.

6. If pieces of the drill bit or fragments fall into the hole, use a magnet to extract them promptly.

7. Regularly grind the column teeth of the drill bit, ensuring the height of the column teeth is between 8-9mm after grinding.

8. When replacing the drill bit, be mindful of the diameter change. If the hole has not been fully drilled due to drill bit wear, do not replace the worn bit with a new one, as this may lead to "bit jamming."

9. High drilling efficiency and prolonged drill bit lifespan depend on the proper coordination of axial pressure and rotary speed. Different rock layers will affect the ratio of rotary speed to axial pressure. The minimum axial pressure applied to the hammer should be sufficient to avoid rebound during operation. The rotary speed can be adjusted based on the size of the rock debris particles.

10. It is strictly forbidden to reverse the hammer or drill rod inside the hole to prevent accidents such as the hammer falling into the hole.

11. In downward drilling, when stopping drilling, do not immediately stop supplying air to the hammer. Lift the drill to perform a strong blowout and only stop the airflow after the hole is clear of rock debris and powder. Then, lower the drilling equipment and stop the rotation.

4. Maintenance and Upkeep Under normal drilling conditions, the hammer should be inspected, cleaned, and reassembled every 200 working hours. When drilling water holes or using mud for debris removal, inspections should be conducted every 100 hours. This work should be performed by qualified personnel in a repair workshop.

1. Disassembling the Hammer The hammer should be disassembled on a dedicated workbench (which can be provided by our company). Please refer to the usage instructions for the specialized workbench.

5. Cleaning, Inspection, and Repair

Thoroughly clean all disassembled parts using a cleaning agent and blow them dry with compressed air.

Inspect all parts for damage or scratches. If any parts are damaged, use a file, scraper, or fine oilstone to smooth and restore them (piston components can be ground on lathe equipment). If micro-cracks or breakages are found, replace the damaged parts with new ones.

Measure the outer diameter of the piston and the inner diameter of the cylinder using a micrometer and bore gauge. If the clearance is too large, replace the piston or cylinder with new parts.

Inspect the wear condition of the coupling sleeve. If the outer diameter is worn down below the allowable limits, replace the sleeve with a new one.

Check the wear condition of the spline on the coupling sleeve. Insert a new drill bit into the coupling sleeve spline and rotate it. If the rotation range exceeds 5mm, replace the coupling sleeve.

Apply lubricating oil to all parts of the repaired and ready-to-assemble components.

Note: For optimal hammer performance, please use genuine parts from our company. Visit our website at www.zzgloborx.com for authentic parts.

6. Hammer Assembly

Place the lower end of the outer tube upwards on the ground and insert the small end of the bushing into the outer tube, tapping it into place with a copper rod.

Place the large end of the drill bit down on the ground, apply a layer of grease to the internal threads of the outer tube, and insert the coupling sleeve's large outer diameter into the drill bit. Install the retaining ring and "O" ring onto the small outer diameter of the drill bit. Then, rotate the drill bit, coupling sleeve, and retaining ring into the outer tube.

Place the outer tube with the drill bit on the workbench. Insert the gas distribution seat into the inner cylinder using a copper rod, place the piston into the cylinder, and push it into the outer tube from the top. Tap it into place with a copper rod.

Insert the spring and check valve, ensuring that the check valve moves freely.

Apply grease to the internal threads of the outer tube and screw in the rear joint.

Use a long wooden stick to check if the piston moves freely.

7. Common Troubleshooting Methods

Fault 1: Insufficient or no lubrication, causing premature wear or damage. Cause: Lubricating oil does not reach the hammer’s impact structure. Solution: Check the lubrication system, adjust the oil injector, and increase the oil supply.

Fault 2: Hammer not working or working abnormally. Causes:

• Air passage blocked.

• Excessive gap between the piston and inner or outer cylinder, or between the piston and gas distribution seat.

• Hammer clogged with debris.

• Piston or drill bit tail broken.