Top hammer drill rod plays an important role in drilling operations in mining, construction and geological exploration. However, a rupture of the top hammer drill rod can result in serious equipment damage, downtime and even safety incidents. Therefore, it is very important to analyze the causes of the fracture in order to take effective preventive measures. The following are the main reasons for the fracture of the top hammer drill rod and their analysis:

1. Material fatigue and stress concentration

· Fatigue accumulation: The top hammer drill rod works under repeated impact loads, especially in hard rock formations, prone to small cracks. These cracks gradually expand over time, eventually leading to fatigue failure of the material. Fatigue breaks usually occur in weak parts of the drill rod, such as threaded joints or welds.

· Stress concentration: Irregular or defective drill rod geometry (such as scratches, pits, thread damage, etc.) can lead to stress concentration, making local areas bear excessive stress, which accelerates the formation and spread of cracks.

2. Overload

· Exceeding design load: If the drill rod is subjected to impact force, torque or tension beyond its design limit, it may cause the material to yield or break. Especially in hard rock formations, too high impact pressure or too fast drilling speed can increase the load on the drill rod beyond its capacity.

· Improper operating parameters: Unreasonable drilling speed, shock frequency, air pressure and other operating parameters may lead to excessive stress on the drill rod, increasing the risk of fracture. For example, a high impact frequency may cause the drill rod to bear too much impact load in a short period of time, resulting in fatigue accumulation.

3. The thread connection is faulty

· Thread wear or damage: thread is the key part of the drill rod connection, if the thread wear or damage, the connection strength will be greatly reduced, easy to cause fracture. Causes of thread damage may include improper installation, insufficient lubrication, and incomplete cleaning.

· Weak connection: Weak or loose thread connections can cause relative displacement of drill rod during work, resulting in additional stress and vibration, which accelerates fatigue fracture. In addition, a poor seal at the threaded joint can also allow mud or water to enter, corroding the thread and further weakening the connection.

4. Corrosion and aging

· Environmental corrosion: The top hammer drill rod is exposed to humid, acidic or alkaline environment for a long time, especially groundwater or seawater containing salt, which is prone to corrosion. Corrosion weakens the drill rod, especially at threaded connections, and can lead to local thinning, increasing the risk of fracture.

· Material aging: The drill rod material may age over time, especially in high temperature or high humidity environment, the mechanical properties of the material will gradually decline, resulting in weakened strength and easy to break.

5. Manufacturing defects

· Material quality problems: if the quality of the raw materials used in the drill rod is unqualified, such as alloy composition does not meet the standard, excessive impurities, etc., it may lead to insufficient strength and toughness of the material, and it is easy to break during use.

· Process defects: There may be process defects in the manufacturing process of drill rod, such as poor welding, improper heat treatment, uneven surface treatment, etc. These defects will affect the overall performance of the drill rod and increase the possibility of fracture.

6. Improper maintenance

· Lack of regular inspection: If the drill rod is not inspected and maintained regularly, cracks, wear, or other potential problems that are detected early may be missed, worsening the problem and eventually triggering a fracture.

· Insufficient cleaning and lubrication: the drill rod should be cleaned in time after use to remove soil, mud and other impurities to prevent corrosion and thread damage. At the same time, the thread connection should be applied with an appropriate amount of grease to reduce friction and ensure a firm connection.

· improper storage: If the drill rod is not properly kept during storage, it may be affected by the external environment, such as moisture, corrosion, etc., which will lead to the deterioration of material properties and increase the risk of fracture.

7. The geological conditions are complex

· Hard or uneven formations: When drilling in hard or uneven formations, the drill rod may be subjected to uneven impact forces and torque, resulting in excessive local stress and increasing the risk of fracture. Especially when encountering geological structures such as gravel, fault or crack, the load of drill rod will increase suddenly, which is easy to cause fracture.

· Deflection or bending of the hole: If the hole deviates from the intended trajectory, the drill rod may be subjected to additional lateral forces, causing bending or twisting and increasing the likelihood of fracture.

8. The device is faulty

· Impactor failure: The operation of the hammer drill rod depends on the impact energy provided by the impactor. If the impactor is faulty, such as piston stuck, unstable air pressure, etc., it may lead to abnormal impact force, increase the load of the drill rod, resulting in fracture.

· Bit wear or damage: The bit is the part that is in direct contact with the rock, and if the bit is worn or damaged, it may cause excessive reaction forces on the drill rod, increasing the risk of fracture.

9. Other factors

· Temperature variations: In extreme temperature environments, such as cold areas or downhole temperatures, the effect of thermal expansion and contraction of drill rod materials can cause stress changes that increase the risk of fracture.

· Improper transportation and handling: During transportation or handling, if the drill rod is hit, dropped or excessively bent, hidden damage may be caused, affecting its performance and increasing the possibility of fracture.

preventive measure

In order to effectively prevent the fracture of the drill rod, it is recommended to take the following measures:

1. Select high-quality drill rod: Select high-quality drill rod that meets international standards (such as API, ISO, etc.) to ensure the reliability of materials and manufacturing processes.

2. Reasonable setting of operating parameters: according to the geological conditions and the performance of the drill rod, reasonable setting of drilling speed, impact frequency, air pressure and other operating parameters to avoid overload.

3. Strengthen the thread connection management: clean the thread before each connection, apply the appropriate amount of grease to ensure that the thread connection is firm, and regularly check the thread status.

4. Regular inspection and maintenance: Establish a sound inspection system, regularly check the status of the drill rod, especially the thread joints and welds, and timely discover and deal with potential problems.

5. Do a good job of anti-corrosion treatment: for long-term storage or used in high-corrosion environment of the drill rod, anti-corrosion treatment, such as coating anti-rust oil or use of anti-corrosion coating to prevent corrosion.

6. Training operators: Ensure that all operators receive professional training, familiar with the use of drill rod and maintenance requirements, and can operate and maintain equipment correctly.

Sum up

The fracture of the top hammer drill rod is often the result of a combination of factors, including material fatigue, overloading, threaded connection problems, corrosion and aging, manufacturing defects, and improper maintenance. By selecting high quality drill rod, reasonably setting operating parameters, strengthening thread connection management, regular inspection and maintenance, and doing a good job of anti-corrosion treatment, the fracture of the top hammer drill rod can be effectively prevented to ensure the safety and efficiency of drilling operations.