Interference Fit Drill Bit Connection for PDC Stability
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Solution Overview
Problem
Conventional polycrystalline diamond compact drill bits face issues with torque and tension transmission due to loose threaded connections, which are prone to failure under harsh underground conditions, and the difficulty in achieving high precision threads with 3D printing, leading to instability and mechanical weakness.
Innovation Solution
A connecting block structure with positioning members is used to form an interference fit between the steel body connector and the matrix crown, eliminating the need for threaded connections and allowing for 3D printing of the matrix crown, which is then sealed with a molten metal layer, enhancing stability and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded connection is used to connect steel body connector and matrix crown, then connection is achieved, but the connection is prone to loosening and failure under high pressure and impact
Solution Approach 1:
The connection structure is segmented into a connecting block with multiple outer wall planes and a connecting groove with corresponding inner wall planes, creating multiple independent contact surfaces that distribute stress and prevent single-point failure
Solution Approach 2:
The connecting block is inserted into the connecting groove to form an interference fit, with the block nested within the groove structure, creating a mechanically interlocked connection that resists loosening under rotational and impact loads
2Ease of manufacture
If 3D printing is used to manufacture matrix crown, then manufacturing flexibility is improved, but thread precision cannot be achieved
Solution Approach 1:
The threading function is extracted from the matrix crown and transferred to the steel body connector, allowing the matrix crown to be manufactured by 3D printing without threads while the connector provides the precision threading interface
Solution Approach 2:
The steel body connector acts as an intermediary component that bridges the 3D printed matrix crown and the drilling apparatus, providing the precision threading interface that cannot be directly achieved through 3D printing
3Reliability
If welding layer is applied to connect steel body connector and matrix crown, then sealing is improved, but metallurgical bonding is not realized
Solution Approach 1:
The connecting block and connecting groove are pre-designed with interference fit dimensions that ensure immediate mechanical engagement and load-bearing capability upon assembly, before any welding or bonding operations
Solution Approach 2:
The connection utilizes a composite approach combining mechanical interference fit (physical bonding) with welding layer (chemical bonding), creating a multi-mechanism connection that achieves both sealing and strength
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 solution provides stable torque and tension transmission, improves mechanical properties, reduces manufacturing costs, and enhances drilling efficiency while minimizing resource consumption, resulting in a more reliable and efficient oil well drilling apparatus.
Implementation Method 1
The connecting block is inserted into the connecting groove to form an interference fit with the connecting groove
Implementation Method 2
the connection effect is weaker after the welding layer is worn off
Implementation Method 3
which is then sealed with a molten metal layer
Data Source
AI summary
A polycrystalline diamond compact drill bit includes a steel body connector and a matrix crown. The matrix crown is provided with multiple main blades extending axially. A rear end surface of the matrix crown is provided with a connecting block projecting backwardly. A front end surface of the steel body connector is provided with a connecting groove having a shape matching a shape of the connecting block. The connecting block is inserted into the connecting groove to form an interference fit with the connecting groove. The rear end surface and the front end surface are fitted to each other. The periphery of the connecting block is provided with an inner positioning hole. A periphery of the steel body connector is provided with an outer positioning hole penetrating into the connecting groove at a position corresponding to the inner positioning hole.