Drill String Joint with Cylindrical Impact Surfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional drill rods for percussion drilling suffer from hole deviation, thread wear, and premature failure due to stress concentration and bending moments, requiring skilled operators and frequent tightening, which limits their working life and increases costs.
Innovation Solution
A joint system for drill string components that separates rotation and percussive shock wave transmission through two meeting elements, allowing relative axial movement to reduce stress on threads and enhance energy transmission efficiency, thereby extending the service life and reducing operator skill requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded joints are used to connect drill string components, then the components can be securely connected and disassembled, but the threads are subject to wear and stress concentration which limits working life and requires frequent tightening
Solution Approach 1:
The joint is divided into separate functional elements: a male part with a cylindrical connection surface and a female part with a corresponding recess. This segmentation eliminates the threaded structure while maintaining secure connection through direct surface contact, thereby extending service life by removing the wear-prone thread elements.
Solution Approach 2:
The threaded connection element is extracted and replaced with a simple cylindrical interface. By removing the threads entirely, the source of stress concentration and wear is eliminated, allowing the joint to withstand repeated percussion and torsional loads without degradation.
2Power
If threaded joints are used to transmit rotation and percussive forces, then power transmission is achieved, but stress concentration at thread roots and bending moments cause premature failure
Solution Approach 1:
The joint design separates the connection function from the power transmission function. The cylindrical interface provides a large contact area that distributes stresses uniformly, while the surrounding structure handles the transmission of rotation and percussive forces. This segmentation eliminates stress concentration at thread roots.
Solution Approach 2:
The connection surfaces are designed with specific local properties: the male part has a cylindrical surface with controlled geometry, and the female part has a corresponding recess. This local quality optimization ensures uniform stress distribution and prevents bending moments that would cause premature failure.
3Ease of manufacture
If conventional drill rods with threaded joints are used, then they are simple to use and have low tooling costs, but they produce hole deviation and zig-zag-shaped hole walls requiring skilled operators
Solution Approach 1:
The drill rod system is segmented into modular components with standardized cylindrical interfaces. This modularity maintains ease of manufacture while the precise cylindrical geometry of the joint ensures accurate alignment between segments, eliminating hole deviation and producing straight hole walls without requiring skilled operators.
4Reliability
If threaded joints are continuously tightened to ensure secure connection, then proper shock wave transmission is maintained, but the frequent tightening and rattling operations induce excess damage to the joint
Solution Approach 1:
The threaded fastening mechanism is extracted and replaced with a cylindrical interference fit interface. This eliminates the need for continuous tightening and rattling operations, as the cylindrical geometry inherently maintains secure connection while allowing proper shock wave transmission through the joint.
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 joint system enables high-quality hole drilling with reduced operator expertise and lower costs by minimizing thread wear and stress concentration, allowing for longer service life and improved energy transmission efficiency.
Implementation Method 1
relative axial movement is allowed between the male and the female parts when being in an interconnected state of co-operation between the first and second rotation torque transfer means
Implementation Method 2
impact shock waves and rotation torque are arranged to be transferred via the the joint
Implementation Method 3
impact shock waves and rotation torque are arranged to be transferred via the joint
Data Source
Figure 1~2C2
Figure 2a~2b
Figure 3a~3b
AI summary
A joint for joining together drill string components (6, 7) of a drill string for percussion drilling, the joint including a male part (8) and a female part (9) f wherein a first impact surface (10) is arranged to co-operate with a second impact surface (11). When the drill string is in operation, relative axial movement is allowed, between the male (8) and the female (9) parts when the first and the second impact surfaces (10,11) are adjacent to each other. The invention also concerns a male joint part, a female joint part, a drill rod, a shank adapter, a drill head, a drill bit and a drill string component.