Of all the widely available rock drilling tools, Threaded Extension Rod offers the widest variety, the most comprehensive specifications, and the highest economic value.
Basic requirements for Threaded Extension Rod
1. The fusion of high fracture toughness and fatigue strength.
Fatigue fracture predominates in the fracture of the Threaded Extension Rod. The primary cause is that the drill rods must support the rock drill's axial thrust and high-frequency impact force. Additionally, because the Threaded Extension Rod is a long, thin rod, the Extension Rod frequently experiences bending stress during horizontal and oblique rock drilling due to the self-weight of the drill tool group. The Threaded Extension Rod material must possess excellent fracture toughness and fatigue strength.
2. Good elasticity and wear resistance.
Due to changes in the rock drill thrust, the inhomogeneity of the rock, or the presence of fractures, holes, and improper operation, the Thread Drill Rod frequently works under varied bending states during the process of drilling rock, whether it is horizontal, vertical, or oblique operations. Thread Drill Rod will bend and shatter if the bending condition is extreme or if the elasticity of the Threaded Extension Rod is poor. cause an early failure. Therefore, the Threaded Extension Rod needs to be elastic.
The threaded design of the Threaded Extension Rod's two ends is crucial for connecting the entire set of rock drilling equipment and for transmitting the stress of rock drilling. The threaded portion of the Threaded Extension Rod is the most crucial component that fails, and its mechanism of failure is caused by fretting wear and impact wear one after the other. As a result, the life of the Threaded Extension Rod is frequently determined by the wear resistance of the threaded component.
3. Excellent resistance to corrosion.
Because of the combined effects of high frequency, high stress, and water, Threaded Extension Rod's inner holes corrode, which is the main cause of fatigue fracture in the Threaded Drill Rod. As a result, the Threaded Extension Rod needs to resist corrosion well even in wet conditions.
Material Quality:
Extension rods should be made from high-quality materials, typically alloy steels, to ensure durability, resistance to wear, and the ability to withstand the forces encountered during drilling.
Precision Machining:
Extension rods should undergo precise machining to maintain straightness, dimensional accuracy, and concentricity. Precision machining ensures that the rod operates smoothly and without excessive vibration.
Thread Compatibility:
The extension rod must have threads that are compatible with both the drill's chuck and the drill bits. This ensures a secure and tight connection, preventing unintentional detachment during operation.
Size and Length:
Extension rods come in various sizes and lengths. The choice of size and length should be appropriate for the specific drilling task. Using the right-sized extension rod prevents instability and ensures proper torque transmission.
Surface Hardening:
Extension rods often undergo surface hardening processes to enhance their resistance to wear and corrosion. This is especially important for extension rods used in demanding drilling applications, such as rock drilling.
Chamfering and Deburring:
Extension rods should be chamfered and deburred to eliminate sharp edges that could cause injury during handling and to ensure smooth insertion into the drill chuck.
Thread Protection:
Extension rods may come with thread protectors to prevent damage to the threads during transportation, storage, or handling. These protectors help maintain the integrity of the threads for proper connection.
