Composite Drill Bit Scraping-Wheel Cutting Units
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Solution Overview
Problem
Existing drill bits face issues such as high thermo-wear, uneven cutter wear, reduced rock-breaking efficiency, and space constraints due to the combination of scraping-wheel and fixed-blade structures, which affect their performance and application in drilling.
Innovation Solution
A composite drill bit with a scraping-wheel cutting structure disposed on a fixed-blade, featuring an angular deflection range of 20° to 90°, where the scraping-wheel is integrated with the fixed-blade to form a hybrid structure, eliminating the need for a separate supporting structure and optimizing cutter distribution and bit design for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a separate supporting structure is added for the scraping-wheel, then the structural stability is improved, but the device complexity and space occupation increase
Solution Approach 1:
The patent merges the supporting structure function into the fixed-blade itself. The fixed-blade is designed to directly support the scraping-wheel without requiring a separate supporting structure, thus reducing device complexity while maintaining structural stability through the integrated design.
Solution Approach 2:
The fixed-blade is given multiple functions: it serves as both the support for the scraping-wheel and as a structural component of the drill bit. This multi-functionality eliminates the need for dedicated supporting structures, reducing overall device complexity while maintaining stability.
2Reliability
If more cutters are fixed on the PDC bit, then the wear rate of each cutter decreases, but the rock-breaking efficiency reduces
Solution Approach 1:
The patent introduces a rotating scraping-wheel with cutters that dynamically engage and disengage from the rock surface. This dynamic action allows cutters to work in alternating sequences, reducing continuous wear on individual cutters while maintaining effective rock-breaking through the rotating motion that exposes fresh cutter edges.
Solution Approach 2:
The scraping-wheel rotates to periodically bring different cutters into contact with the rock surface. This periodic action distributes wear across multiple cutters over time, extending their service life while the continuous rotation maintains rock-breaking efficiency through alternating cutting sequences.
3Productivity
If the angular deflection of the scraping-wheel is increased, then the rock-breaking efficiency is improved, but the bearing load increases
Solution Approach 1:
The scraping-wheel is positioned with a preliminary angular deflection that optimizes the initial contact angle with the rock surface. This pre-set angle maximizes rock-breaking efficiency at the point of contact while the bearing design accommodates this angle through appropriate load distribution and selection of bearing capacity.
Data Source
AI summary
A composite drill bit has one or more scraping-wheel cutting units disposed on fixed-blade. The drill bit comprises a bit body, fixed-blades, and scraping-wheels. The angular deflection of the scraping-wheel is in the range of 20°≤|α|≤90°. The scraping-wheel cutting unit has a scraping-wheel shaft and a scraping-wheel with cutters disposed thereon. The scraping-wheel cutting unit is disposed on the fixed-blade by a rotary connection.