In the increasingly developing field of geotechnical engineering, large-diameter down-the-hole hammer drilling technology has become an indispensable drilling tool under various complex geological conditions due to its significant advantages, such as high efficiency, strong deep drilling capabilities, and high cost-effectiveness. As the core component of this technology, the Φ800mm down-the-hole drill bit’s button arrangement design is directly related to the drilling efficiency, the service life of the drill bit, and the quality of the hole. The scientific and reasonable arrange the button design can not only effectively improve the rock-crushing effect but also significantly reduce energy consumption and operating costs while ensuring the durability of the drill bit. This article will discuss the crucial elements of arranging the button design for Φ800mm down-the-hole drill bits to help you better understand and apply this technology.
Basic principles of button arrangement design
- Uniform distribution: the first principle of button arrangement is to ensure that each cutting tooth is evenly distributed at the bottom of the hole so that the power consumption per unit volume of rock is minimized, that is, the crushing effect is optimal.
- Balanced strength and wear: ensure that the column teeth have sufficient strength and wear resistance to prevent some cutting teeth from being damaged prematurely due to uneven stress.
- Rock crushing efficiency: a well-designed button arrangement improves rock crushing efficiency, reduces repeated crushing, and lowers energy consumption.
Key elements of button arrangement design
Determination of the number of buttons
Determining the number of buttons for the Φ800mm down-the-hole drill bit should follow two critical principles: first, impact energy must be evenly distributed at the bottom of the hole while minimizing power consumption for crushing a unit volume of rock; second, the column buttons should be intensity and wear evenly. The number of buttons should be accurately calculated based on the drill bit’s diameter, structure, and impact work size. While theoretical designs often suggest too many buttons, practical applications may require fewer due to factors like drilling pressure and connection methods. For instance, the outer ring can have more buttons for even wear, while the inner ring can have fewer to ensure effective impact energy transmission.
Calculation of button spacing
Reasonable button spacing can ensure that the crushing cross zone between adjacent column buttons is moderate, neither too tight to cause a poor crushing effect nor too sparse to form rock ridges between crushing pits. In the design of the Φ800mm down-the-hole drill bit, determining button spacing needs to comprehensively consider factors such as rock properties, column button diameter, and crushing pit diameter. Generally, for plastic brittle soft rock (uniaxial compressive strength below 100 MPa), the button spacing can be smaller; for brittle rock (uniaxial compressive strength between 100 and 700 MPa), the button spacing should be increased appropriately.
Button-type selection
Different button types have different pressure-depth characteristics and are suitable for rocks of varying hardness. The commonly used button types of Φ800mm down-the-hole drill bits include spherical buttons, ogive buttons, and wedge buttons.
Spherical buttons are ideal for hard rock and solid formations (pressure hardness 4000–6000 MPa) due to their high penetration depth and excellent wear resistance. Ogive buttons work well in medium-hard and solid formations (pressure hardness 2000–4000 MPa), providing strong cutting force and effective rock crushing. Wedge buttons are suited for soft, medium-soft, and medium-hard formations (pressure hardness ≤2000 MPa), offering low penetration resistance and good self-sharpening properties.
In designing the Φ800mm down-the-hole drill bit, we should reasonably select the button type based on the formation conditions to ensure optimal drilling efficiency and extend the drill bit’s service life.
Arrange the button scheme
Different button arrangements can be designed based on the rock characteristics and the drill bit’s structural form. For the Φ800mm down-the-hole drill bit, the button arrangement should prioritize overall stability and rock-crushing efficiency. Typically, the column buttons in the inner ring should provide greater penetration depth and cutting action to enhance rock-crushing efficiency, while the buttons in the outer ring should focus on wear resistance to ensure the drill bit’s longevity.
Selection of column carbide button material
The selection of column carbide material is directly related to the drill bit’s wear resistance and service life. The commonly used column carbide button materials on the market include YG8, YK05, etc. These materials possess high hardness, bending strength, and impact resistance, making them suitable for drilling in various formations. In designing the Φ800mm down-the-hole drill bits, it’s essential to select the appropriate column carbide button material based on factors like formation hardness, drilling depth, and speed. For hard rock drilling, materials with higher hardness and greater bending strength should be chosen, while for soft rock, alloys with better wear resistance are preferable.
Conclusion
The button arrangements design of the Φ800mm down-the-hole drill bit is the key to ensuring its efficient and stable operation. By designing reasonable button arrangements, the rock-crushing efficiency and service life of the drill bit can be significantly enhanced, while also ensuring the quality of the borehole. In the future, with the continuous advancement of science and technology and the continuous accumulation of engineering practice, the button arrangements design of the Φ800mm down-the-hole drill bit will be more refined and intelligent, providing strong technical support for the rapid development of geotechnical engineering. In practical applications, continuous optimization and innovation of button arrangements design will further promote the widespread application of large-diameter down-the-hole hammer drilling technology and provide efficient and reliable solutions for drilling operations under various complex geological conditions.
