Down-the-hole hammer drill bit retention and porting
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Solution Overview
Problem
Conventional down-hole hammers face challenges with porting arrangements that either require machining weakening grooves, increasing manufacturing costs, or result in higher piston breakage frequencies, and are difficult to disassemble due to torsional forces and vibrations.
Innovation Solution
A down-hole hammer design that incorporates a hollow porting tube extending from the top adapter sub into the drill bit bore, eliminating the need for a foot valve and allowing for improved alignment and debris prevention, with a ported piston compression chamber volume adjustable through inserts, and featuring sacrificial drive engagement pins for easier assembly and disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional porting arrangements are used with machining weakening grooves, then fluid management is achieved, but manufacturing costs increase
Solution Approach 1:
The invention extracts the foot valve component from the system by using a hollow porting tube that extends into the drill bit bore. This eliminates the need for separate foot valve assembly and the weakening grooves required in conventional designs, thereby reducing manufacturing complexity and cost while maintaining structural integrity and reducing piston breakage.
Solution Approach 2:
The hollow porting tube serves multiple functions: it provides fluid porting, acts as a guide for the piston, prevents debris entry, and eliminates the need for foot valve components. This multi-functionality reduces the number of parts and manufacturing steps, lowering costs while improving reliability.
2Device complexity
If conventional porting arrangements with foot valves are used, then fluid control is achieved, but device complexity increases
Solution Approach 1:
The foot valve is extracted from the system and its functions are integrated into the hollow porting tube structure, reducing the total component count and simplifying assembly procedures.
Solution Approach 2:
The porting function and foot valve function are merged into a single hollow porting tube component, eliminating the need for separate foot valve assembly and reducing overall device complexity.
3Ease of operation
If conventional drive engagement mechanisms are used, then power transmission is achieved, but disassembly difficulty increases due to torsional forces and vibrations
Solution Approach 1:
The drive engagement mechanism is segmented into sacrificial pins that can be easily removed, allowing for simple disassembly despite the presence of torsional forces and vibrations during operation.
Solution Approach 2:
Sacrificial drive engagement pins are used instead of permanent fasteners. These pins can be easily replaced after wear or seizure due to torsional forces, simplifying maintenance and disassembly while ensuring reliable power transmission during operation.
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 design reduces manufacturing costs, minimizes piston breakage, and simplifies disassembly by eliminating the need for a foot valve and enhancing debris resistance, while maintaining efficient fluid management and operational reliability.
Implementation Method 1
The piston is driven reciprocatingly by compressed fluid (usually air) supplied through a top adapter sub
Implementation Method 2
The lower face of the piston forms a hammer which impacts on the upper face of the anvil
Implementation Method 3
a closed chamber is formed above said guide bush in which fluid is trapped and progressively compressed until impact between the piston and drill bit. The compressed fluid (usually air), combined with some rebound resulting from impact, takes the piston back to the top of its stroke
Data Source
Figure 1
Figure 2
Figure 3~3B
AI summary
There is provided a downhole hammer including a drill bit (2) retained by short (4) and long (5) drive pins in the bore of a driver chuck (1). The chuck (1) and bit (2) shank have machined longitudinal grooves (3), every second bit shank groove being blind and connected to the adjacent open groove by a short-pin-length relief. The shorter pins (4) are inserted into the visible holes formed by the alignment of the open drill bit grooves and driver chuck grooves (3). The chuck (1) is then indexed which shunts the short pins (4) sideways until the longer pins (5) are insertable. The driver chuck (1) and drill bit (2) are engaged rotationally. The bit (2) slides by the desired distance due to the shorter pins (4) being entrapped in the blind grooves. The arrangement does not require a bit shank extension to accommodate a conventions bit retainer ring.