During the drilling, the drill rod not only bears the tension, compression, bending, and torsional cyclic stresses imposed by the hydraulic rock drill with high frequency and impact energy but also to huge impact load. In addition, the service conditions of drill rods are very harsh, and there are differences in the production process of drill rod manufacturers, so its service life is uneven. Improving the service life of drill rods can both improve rock drilling production efficiency and help enterprises save costs , which is inseparable from the quality stability of the drill rod.
Factors affecting the quality stability of the drill rod
Many factors affect the quality and stability of drill rods, including material quality, equipment factors, manufacturing processes, use environment, operating specifications, maintenance, and storage conditions.
Material quality
The quality of the material is a significant factor influencing the stability of the drill rod’s overall quality. The drill rod functions under dynamic load conditions and necessitates high fatigue resistance, wear resistance, and impact resistance. These properties are crucial to ensure its normal operation in complex environments and various working conditions. If the material quality does not meet the standards, the drill rod may break, deform, and other problems during use, seriously affecting its service life and working stability. Therefore, manufacturers should select high-quality raw materials and conduct strict quality control and testing to ensure that material quality meets standard requirements.
Equipment factors
The equipment required to produce drill rods includes straightening machines, lathes, upsetting machines, friction welding, milling machines, thread lathes, well carburizing furnaces, well tempering furnaces, internal and external shot blasting machines, air-cooled quenching equipment, anti-corrosion treatment equipment.
① There are many manufacturers of straightening machines, lathes, upsetting machines, friction welding, milling machines, and internal and external shot blasting machines, and the equipment is relatively mature. As long as the process is reasonable and the personnel is skilled in operation, there are no problems.
②The quality of thread processing has a greater impact on the drill rod. The use of imported lathes to process threads with better finish and standardized thread shape has a certain effect on quality improvement.
③Rock drilling tools’ anti-corrosion treatment is also very effective in improving the quality of drill rods. The smoothness of circulation in the well-carburizing furnace directly affects the depth of the carbon layer, the surface carbon content, and the uniformity of the metallographic organization of drill rod, which is very critical to the quality of drill rod. The uniformity of drill rods in the furnace and the uniformity of different drill rods at the same height in the furnace also have a direct influence on the quenching of rods later.
Manufacturing process
The manufacturing process is another critical factor affecting the stability of drill rod quality. The manufacturing process of drill rods involves several processes, such as heat treatment, machining, and surface treatment. Processes with a significant impact on the uniformity of drill rod quality include the carburizing process and the secondary quenching process.
① Carburizing process
For deep well type carburizing furnace, only by ensuring the uniformity of temperature and carbon potential in the furnace can the uniformity of the carbon layer depth and surface carbon concentration of drill rod be guaranteed.
② Secondary quenching treatment
The drill rod after high-temperature tempering is placed in an 8-meter well-type carburizing furnace for secondary heating and quenching, protected by methanol and propane atmosphere, to ensure that the temperature and carbon potential in the furnace is controlled within a reasonable range. After the carbon potential is reached, keep it warm for 1 hour and put it in an air-cooled quenching device for quenching. After it is released from the furnace, it is quickly hoisted into the air-cooled tower with adjusted wind speed by a crane, and the temperature is measured inside and outside the drill rod with a temperature measuring gun and an induction thermocouple to ensure the cooling rate of drill rod. After the temperature is reached, adjust the frequency of the variable frequency centrifugal fan immediately, and measure the temperature inside and outside the drill rod with a temperature measuring gun and an induction thermocouple to ensure that the drill rod cools to room temperature at a cooling rate of ≥3°C/s. After tempering, the organization is tested, the hardness of the drill rod surface and the heart can be controlled in 1HRC, and the upper middle and lower metallographic organization is uniform to achieve the uniformity of the hardness and metallographic organization of the second quenching drill rod.
In short, if the manufacturing process is unreasonable or the control is not strict, various quality problems may occur in the drill rod, such as cracks, pores, and inclusions. Therefore, manufacturers should formulate strict process flow and control parameters and conduct strict quality inspection and control to ensure that the manufacturing process of drill rods meets standard requirements.
Use environment
The use environment also has a definite impact on the quality stability of the drill rod. Different usage environments, such as temperature, humidity, and pH, will have different effects on the material and surface treatment of the drill rod. For example, in a high-temperature environment, the material of the drill rod may suffer from oxidation, corrosion, and other problems; in a low-temperature environment, the material of the drill rod may become brittle or have cold cracks; in a corrosive environment, the materials of drill rods may corrode or undergo chemical reactions. These environmental factors will hurt the quality stability of the drill rod. Therefore, users should consider the characteristics and requirements of the use environment when selecting a drill rod and choose suitable drill rod materials and processes to maintain its quality stability.
Operating specifications
Operating specifications also have a definite impact on the quality stability of the drill rod. During use, if the operation is not standardized or the method of use is improper, it may cause wear, deformation, and other problems with the drill rod. For example, during the drilling process, if the force is too strong or the rotation speed is too fast, the drill rod may bear excessive load and break. Therefore, users should abide by the operating specifications and instructions, use the drill rod correctly, and avoid unreasonable use methods to maintain the quality stability of the drill rod.
Maintenance
Maintenance is crucial to the quality and stability of the drill rod. Correct maintenance can extend the service life of the drill rod and improve its working performance. If the drill rod is in poor working condition for a long time or lacks necessary maintenance, its performance and quality stability will decrease. For example, insufficient lubrication will lead to increased friction and wear; inadequate cleaning will lead to the accumulation of dirt and impurities; improper installation and disassembly will cause damage to the drill rod or reduced performance. Therefore, users should conduct regular maintenance on the drill rod and pay attention to employing correct usage and operational methods to preserve its quality stability.
Storage conditions
Storage conditions also have an impact on the quality stability of the drill rod. If the drill rod is stored improperly, it may suffer from moisture, corrosion, oxidation, and other problems. For example, a humid environment may cause the drill rod to rust; a high-temperature environment may lead to an oxidation reaction and deterioration of the drill rod. Therefore, manufacturers and users should choose appropriate storage conditions, maintain a dry and ventilated environment, and prevent the drill rod from being affected by adverse factors such as moisture and high temperature.
Conclusion
To ensure the quality stability of the drill rod, manufacturers should enhance quality control and testing. Users need to employ and maintain the drill rod correctly. While also paying attention to the selection and maintenance of storage conditions. By comprehensively considering these factors, the service life and working stability of the drill rod can be effectively improved.
