Welcome to Kings Rock Tools - Home of the Rock Drilling Tools!
Causes of early failure of B22 taper drill rod
Release time:
Apr 26,2025
Source:
B22 taper rod breakage at the root of the collar is usually caused by a combination of factors. The following are the possible causes and analysis:
1. Improper material selection
Material problem: the quality of rod steel is not up to standard (such as impurities, inclusions, carbide segregation) or improper heat treatment (excessive hardness leading to increased brittleness).
2. Manufacturing process defects
In the production process, such as uneven heating during forging, insufficient forging ratio, will make the internal organization of the material is not uniform, there are defects; root transition area there are sharp edges or machining cutter marks, the formation of stress concentration points; improper control of the heat treatment process, resulting in the organization of the collar root parts and poor performance, will also reduce the tapered rod's fracture resistance.
3. Stress concentration
Structural design: the root is a sudden change in cross-section area (such as rebate groove, transition fillet is too small), easy to produce stress concentration.
Fatigue fracture: under long-term cyclic loading, tiny cracks sprout and expand from the stress concentration, and eventually fracture (the fracture may show a shell-like pattern).
4. Improper use
Overload impact: the rock drilling encountered hard rock or jamming did not stop in time, resulting in instantaneous impact force exceeding the material strength.
Off-load operation: the rod is not perpendicular to the rock surface, resulting in the bending stress concentrated at the root.
Insufficient lubrication: poor lubrication of the connection part leads to extra friction stress.
5. Maintenance and assembly problems
Worn or corroded threads: The threads of the collar are worn, corroded or not tightened during assembly, resulting in uneven local stresses.
Fatigue life depletion: rods are not replaced in time after long-term use, and accumulated damage leads to fracture.
6. Environmental factors
Corrosive environment: downhole humidity, acidic water and other corrosive media accelerate crack expansion.
Low temperature operation: material toughness decreases under low temperature environment, brittle fracture risk increases.
7.Solution Suggestion
Check fracture morphology: Observe whether there are fatigue lines, old cracks or material defects.
Optimize the design: Increase the root transition fillet and adopt smooth stress transition structure.
Standardize operation: avoid partial load and overload, and regularly check the thread connection status and lubrication.
Material upgrading: choose higher toughness steel.
Key words:
Related News
As an original manufacturer of premium rock drilling hollow steel and tools, we ensure that you will always get the right rock drilling tools, knowledge, support and perfect solution for your operation.
LEAVE US A MESSAGE
If you would like to get more product details and quotations