Mud Shaft Impact Package for Rotary Percussive Drilling Rig
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Solution Overview
Problem
Rotary percussion drilling rigs face limitations in drilling performance, especially for deep boreholes, due to inefficient energy transfer and potential damage from axial impacts, as existing damping solutions like pneumatic elements are costly and impractical, leading to reduced service life and increased risk of drill rod breaks.
Innovation Solution
A flushing shaft with an impact package composed of annular steel and vulcanized elastomer disks, arranged behind the down-the-hole hammer, decouples axial impacts from the two percussion systems, ensuring controlled deformation and heat dissipation to prevent material liquefaction, allowing independent adjustment of impact energies and improved energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pneumatic damping element is used to decouple axial impacts, then the down-the-hole hammer is protected from damage, but the device becomes expensive and complicated
Solution Approach 1:
The patent changes the material parameters by using elastomer discs with specific viscoelastic properties instead of complex pneumatic systems. The elastomer material parameters (viscosity, elasticity) are optimized to provide adequate damping while simplifying the overall device structure.
Solution Approach 2:
The elastomer discs are designed as simple, inexpensive replacement components that can be easily swapped out when worn, replacing expensive and complex pneumatic damping elements that require maintenance and are difficult to replace.
2Device complexity
If an elastic disk is used as a damping element, then the construction is simplified, but the disk heats up and liquefies from impact, losing damping effect
Solution Approach 1:
The patent employs composite material structure by combining elastomer discs with metal discs. The elastomer provides damping while the metal discs conduct heat away from the impact zone, preventing the elastomer from overheating and liquefying.
Solution Approach 2:
Different parts of the damping assembly have different thermal properties - the elastomer discs are positioned where damping is needed while metal discs are positioned to conduct heat away from critical areas, creating local quality variations in thermal management.
3Device complexity
If no damping element is used, then the construction is simplest, but damage to the down-the-hole hammer or drill rods occurs quickly
Solution Approach 1:
The damping function is segmented into multiple thin elastomer discs arranged in sequence, each disc handling a portion of the impact energy. This segmented approach provides adequate protection while keeping individual discs simple and the overall structure manageable.
4Productivity
If two drill heads are used with hydraulic hammer, then drilling performance is improved, but impact energy is divided and transmission loss occurs in deep boreholes
Solution Approach 1:
The patent extracts the damping function from the impact transmission path by placing elastomer discs in the drill rod, separating the impact decoupling function from the energy transmission function. This allows impact energy to be selectively damped while maintaining efficient energy transmission to the drill bits.
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
This solution enhances drilling performance and extends the service life of rotary percussion drilling systems by decoupling axial impacts, preventing drill rod breaks, and maintaining flexibility in system operation, allowing for high drilling speeds and efficient energy use.
Implementation Method 1
An impact package is arranged in the receptacle, which includes a number of annular steel disks and preferably vulcanized elastomer disks. An elastomer disc is always arranged between two steel discs.
Implementation Method 2
The impact package is arranged in the receptacle, which includes a number of annular steel disks and preferably vulcanized elastomer disks... to decouple the axial impacts generated by the two percussion systems
Implementation Method 3
ensuring controlled deformation and heat dissipation to prevent material liquefaction
Implementation Method 4
The drill cuttings broken up by the two drill heads are picked up by a flushing medium, for example air, water, suspensions, etc., which is pumped into the rods and brought to the surface.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A mud shaft for fitting into an outer drill string (5) of a rotary percussive drilling rig (1) having an overburden percussion mechanism is described. In this case, the rotary percussive drilling rig (1) has a central chisel bit (3), which is rotationally driven and is subjected to axial blows by a down-the-hole hammer (4), and a rotationally driven drill bit (6) subjected to axial blows by an external hammer (7). The mud shaft (8) has a cylindrical body, on the axial end regions of which standardized connecting threads (81, 82) are provided for connecting to the outer drill string (5) and to the external hammer (7), and which, at its end region facing the down-the-hole hammer (4) in the fitted state, has a blind-hole-like receptacle (83) which is connected to a supply bore (94) for the down-the-hole hammer (4). Arranged in the receptacle (83) is an impact stack (9) which comprises a number of annular steel discs (91) and, preferably vulcanized, elastomer discs (92). In this case, an elastomer disc (92) is always arranged between each two steel discs (91).