Design Origin

　　With the increasing trend of large-scale buildings, in pile foundation construction, large holes, deep piles, and hard rock penetration have become new keywords, continuously imposing higher requirements on rotary drilling rigs, drilling tools, and construction methods. Hard rock drilling is difficult, but it also fascinates construction units because high difficulty brings high returns; the construction cost of a single pile hole exceeding 100,000 yuan is no longer uncommon. "To do a good job, one must first sharpen one's tools." A cost-effective drilling bucket will undoubtedly yield twice the result with half the effort, mainly reflected in:

　　1. Time is money: The drilling bucket equipped for large rotary drilling into hard rock must be durable and wear-resistant, minimizing repair and maintenance time. A single SANY 4-series rotary drilling rig drilling into hard rock can generate about 30,000-50,000 yuan per day; wasting time on drilling bucket repairs is unacceptable.
　　2. Efficiency is life: For rock layers of different hardness, the arrangement of cutting teeth varies to ensure optimal drilling efficiency. Targeted tooth arrangement can significantly improve drilling efficiency and reduce tooth consumption. A single construction project consumes about hundreds of thousands of yuan in teeth; reasonable tooth arrangement can greatly reduce construction costs.

　　Design Concept

　　The first step in hard rock drilling is usually core drilling with a cutting tooth core barrel, which is also the speed-controlling step in hole formation. The SANY Pile Machinery Research Institute, summarizing over ten years of experience and using the most advanced scientific research methods, has developed the heavy-duty series cutting tooth core barrel drill. The main design concepts include:

　　1. Super-strong structure: Based on the characteristics of high torque and high crowd force during hard rock drilling, the barrel top is newly designed: using static and dynamic simulations, the connection square, ribs, and top plate structures are optimized to reduce local stress concentration. Steel plates are cut using fully automatic online cutting, and weld treatment follows the precision requirements of drilling rigs. The core barrel sample, through dozens of strain gauges, tests the stress on welds and stress concentration points during drilling, ensuring that even when stalled on the SR485 rotary drilling rig, the core barrel has sufficient strength and rigidity.


　　2. Super wear-resistant barrel: During the use of cutting tooth core barrel drills, wear and detachment of guide strips are common failures. The guide strips of SANY heavy-duty cutting tooth core barrel drills are made of high-strength wear-resistant steel, with wear resistance more than twice that of Q345B. Welding uses preheating and heat preservation to ensure they do not detach during long-term drilling.


　　3. Customized tooth arrangement and barrel height: Using the most advanced digital methods, the optimal number of teeth and cutting tooth angles for drilling rocks of different hardness are calculated to ensure optimal drilling efficiency. In addition, for the same hole diameter, different barrel heights can be customized according to drilling efficiency and coring requirements to meet different customer needs.
　　Construction Performance

　　In the Shenzhen Shenye Century Valley Urban Renewal Unit Phase I project, the newly developed SANY 1.2-meter heavy-duty cutting tooth core barrel drill, mounted on the SANY SR525, was used for core drilling and achieved efficiency that satisfied the customer. The project has a designed pile diameter of 1.5m and pile depth of 40m, with the lower moderately weathered to slightly weathered granite hardness reaching 60-70MPa. The construction unit originally used a 1.5m roller cone core barrel + coring tool for coring, but the drilling efficiency of the roller cone core barrel was low, only 0.96m/h, and the hole formation time for a single pile was about one and a half days. Upon our suggestion, the customer switched to the SANY 1.2m heavy-duty core barrel for drilling and coring, and the effect was very obvious: the drilling efficiency reached 2.15m/h, and the hole formation time for a single pile was shortened to less than one day, speeding up construction for the customer; at the same time, because the cost difference between cutting teeth and roller cones is geometric, the heavy-duty cutting tooth core barrel greatly saved construction costs for the customer.


　　Construction Summary

　　1. Through on-site observation and data collection, under the conditions of the SR525's high crowd force, high torque, and high-hardness granite at the bottom, the connection square, ribs, and top plate of the heavy-duty core barrel were very stable, with no bending or deformation.
　　2. The barrel guide strips, under working conditions where the surrounding rock hardness was as high as 70MPa, after drilling 6 piles, showed almost no wear, verifying the high wear resistance of the new steel.
　　3. The pure drilling efficiency of the heavy-duty core barrel far exceeded that of the roller cone core barrel, and the tooth holders showed no wear. Reasonable tooth arrangement is the guarantee of efficient drilling, and excellent construction performance brings greater value to customers.