Composite Drill Bit with Scraping Wheel for Rock Breaking
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Solution Overview
Problem
Current drill bits, such as tri-cone and PDC bits, face inefficiencies in rock-breaking due to high energy consumption, short service life, and uneven wear, with tri-cone bits experiencing bearing failure and PDC bits suffering from thermal wear and uneven cutter wear.
Innovation Solution
A composite drill bit featuring a scraping-wheel cutting unit with large angular deflection and fixed cutters on the bit body, allowing for crosswise cutting and forming a mesh-like pattern that increases rock-breaking efficiency and service life by distributing cutting forces and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tri-cone bits break rock by impact crushing with high rotating speed, then rock-breaking efficiency is improved, but bearing service life deteriorates due to large impact and high load amplitude
Solution Approach 1:
The patent combines two different cutting mechanisms into a single hybrid drill bit: PDC cutters for shearing rock and a single cone with teeth for impact crushing. This merging allows the drill bit to utilize the advantages of both methods - the high efficiency of PDC cutting and the effectiveness of impact crushing for hard rock, while distributing the mechanical stress away from the bearings through the alternative crushing mechanism
Solution Approach 2:
The drill bit employs composite cutting structures by integrating PDC (polycrystalline diamond compact) cutters with a single cone bearing assembly. The PDC cutters are affixed to the bit body while the single cone with hard-facing teeth provides impact crushing capability. This composite approach allows the system to switch between cutting and crushing modes, improving overall rock-breaking efficiency while reducing bearing load through the alternative crushing path
2Productivity
If PDC cutters continuously cut rock, then rock-breaking efficiency is improved, but cutter wear rate increases due to high temperature from intense friction
Solution Approach 1:
The hybrid drill bit creates periodic action by alternating between PDC cutter shearing and cone tooth impact crushing during the drilling process. The single cone rotates at a different speed than the bit body, creating a varying cutting pattern where PDC cutters and cone teeth take turns engaging the rock. This periodic alternation prevents continuous high-temperature friction on PDC cutters, allowing them to cool periodically and reducing thermal wear
Solution Approach 2:
The single cone with teeth acts as an intermediary between the drill bit and the rock formation. Instead of PDC cutters continuously bearing the full cutting load, the cone teeth periodically intervene to perform impact crushing, especially effective for hard and abrasive rock. This intermediary mechanism shares the rock-breaking task, reducing the continuous thermal and mechanical stress on PDC cutters
3Ease of manufacture
If cutters are distributed on bit body in fixed patterns, then manufacturing is simplified, but cutter wear becomes uneven across different radial areas
Solution Approach 1:
The single cone is designed to rotate relative to the bit body, creating a dynamic cutting pattern. As the cone rotates, its teeth engage different radial positions of the rock formation in sequence rather than fixed positions. This dynamic motion distributes the cutting and crushing workload more evenly across all PDC cutters on the bit body, preventing any single cutter or radial area from experiencing excessive wear while maintaining simple fixed-pattern cutter distribution
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite drill bit enhances rock-breaking efficiency, extends service life, and reduces wear rates through even cutter wear and lower cutting forces, while maintaining a stable and efficient drilling process.
Implementation Method 1
the cutters on the scraping-wheel to break rock by scraping it in succession
Implementation Method 2
cutters that fixed on the bit body and that on the scraping-wheel cut the bottomhole rock crosswise, forming a mesh-like pattern on the bottomhole
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A composite drill bit comprises: a drill bit body (1), a scraping-wheel (2), the drill bit body (1) further comprises a bit leg (3). The scraping-wheel (2) is mounted for rotation on the corresponding journal (6) of the bit leg (3), an outer-ring (4) is deployed on the scraping-wheel (2), wherein: the angular deflection α of the scraping-wheel (2) is in the range of 20° ≤ |α| ≤ 90°, the fixed cutting unit (8) with fixed cutters (8a) fixed thereon is deployed on the drill bit body (1). In the present invention, cutters on the scraping-wheel break rock by means of successive scraping, forming a cross-cutting area on the bottomhole accompanied by the cutters on the fixed cutting unit, thus achieving high rock-breaking efficiency, even wear, high cooling performance, and a longer service life for the cutters, bearings and the drill bit.