Rock Drill Bit Guiding Surfaces for Hole Straightness
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Solution Overview
Problem
Existing rock drill bits face challenges in extending service life, achieving efficient rock removal, and maintaining hole straightness during percussive drilling, particularly in top hammer drilling.
Innovation Solution
The rock drill bit features a design with integrated cemented carbide buttons, a unique configuration of grooves and guiding surfaces, and a flushing medium channel, which allows for efficient rock removal and extended tool life by maintaining button shape and guiding precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional rock drill bit design is used, then basic drilling function is achieved, but service life is limited due to button shape degradation and guiding surface wear
Solution Approach 1:
The front face is segmented into a cavity and an endless land, with buttons strategically positioned in both regions. This segmentation allows differential functionality: buttons in the cavity receive flushing fluid for cooling and shape maintenance, while buttons in the land provide structural support and guiding function, extending overall service life.
Solution Approach 2:
The design implements local quality by creating a cavity with enhanced flushing fluid flow specifically positioned to cool and maintain the shape of certain buttons. This localized quality enhancement targets the most critical wear zones, preserving button geometry where it matters most for extended service life.
2Productivity
If simple drill bit structure is used, then manufacturing is easier, but rock removal efficiency is insufficient
Solution Approach 1:
The structure is segmented into functional zones: a cavity for flushing fluid circulation, an endless land for button mounting and structural integrity, grooves for chip evacuation, and guiding surfaces for hole straightness. This segmentation enables efficient rock removal through coordinated fluid flow and chip transport while maintaining a manageable structural complexity.
Solution Approach 2:
The drill bit structure employs nested features where grooves are formed within the endless land, and the cavity is integrated into the front face geometry. This nesting approach maximizes functional complexity within constrained dimensions, improving rock removal efficiency without proportionally increasing overall device complexity.
3Manufacturing precision
If drill bit lacks guiding surfaces, then manufacturing is simpler, but hole straightness cannot be maintained
Solution Approach 1:
The endless land serves multiple functions: it provides a mounting surface for buttons, forms the boundary of the cavity, and incorporates grooves for chip evacuation. Additionally, specific portions of the endless land are configured as guiding surfaces that contact the hole wall to maintain straightness. This multi-functionality reduces the need for separate guiding components, simplifying manufacturing while ensuring hole straightness.
4Ease of manufacture
If buttons are mounted only on flat surface, then mounting is simpler, but cooling and flushing efficiency is reduced
Solution Approach 1:
Buttons are segmented into two mounting locations: some are mounted on the endless land for simple structural support, while others are mounted in the cavity where they benefit from enhanced flushing fluid flow. This segmentation allows certain buttons to receive superior cooling and flushing efficiency while maintaining overall manufacturing simplicity.
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 design enhances hole straightness, extends tool life, simplifies regrinding, and reduces machining time, enabling the drill bit to perform effectively in both hard and loose rock conditions.
Implementation Method 1
a fluid channel extends through the drill bit for supplying flushing fluid to the cavity
Implementation Method 2
Axially rearward ends of the lands are provided with projecting, part-cylindrical guiding surfaces
Implementation Method 3
cemented carbide buttons that work the rock by impacting thereupon during simultaneous rotation
Data Source
AI summary
The present invention relates to a rock drill bit for percussive drilling. The drill bit comprises a bit body, a head portion defining a longitudinal center axis. The head portion includes an axially forward rock-crushing surface and a skirt that extends axially rearwardly from the rock-crushing surface. The rock-crushing surface comprises several rock-crushing means. A circumferential outer surface of the skirt is provided with circumferentially spaced apart grooves forming lands therebetween. The grooves and the lands extend generally in an axial direction. An axially rearward portion of a land is provided with a guiding surface. The guiding surface faces radially outwardly. The guiding surface comprises at least one step or a sloping surface such to reduce the diametrical dimension stepwise or continuously, respectively. The guiding surface comprises a first guiding portion and a second guiding portion both situated radially outside of an imaginary extension line of the waist. The first guiding portion projects farther radially outwardly than the second guiding portion relative to the center axis of the drill bit.