Drill Body Chip Flute Geometry for Long-Hole Precision
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Solution Overview
Problem
Drills face challenges in efficiently removing cutting chips during long hole drilling, requiring minimal radial deflection to maintain high-quality hole precision.
Innovation Solution
A drill body design with a central and peripheral chip flute system, where the peripheral chip flute has a specific cross-sectional shape and dimensions to accommodate cutting chips, combined with coolant channels for effective chip removal and stability, providing high bending and torsional stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drill body is designed with large chip flutes to accommodate cutting chips from long hole drilling, then chip removal efficiency is improved, but the bending stiffness and torsional stiffness of the drill body deteriorate
Solution Approach 1:
The patent applies local quality by designing the drill body with varying cross-sectional properties along its length. The drill body has a larger cross-section at the head portion and a gradually reducing cross-section toward the tail portion. This allows the head portion to provide high stiffness for maintaining hole precision, while the tail portion accommodates larger chip flutes for efficient chip removal from long holes.
Solution Approach 2:
The patent resolves the contradiction by transitioning from a uniform cross-sectional design to a variable cross-sectional design along the longitudinal dimension. The drill body cross-section changes from a first cross-section at the head to a second cross-section at the tail, with the area ratio between them being 0.6-0.9. This dimensional variation allows simultaneous optimization of stiffness and chip removal capability.
2Manufacturing precision
If the drill body cross-section is reduced to increase bending stiffness and torsional stiffness, then hole precision is improved, but the capacity to accommodate and remove cutting chips deteriorates
Solution Approach 1:
The drill body is designed with different cross-sectional properties at different locations to fulfill different functions. The head portion has a larger cross-section optimized for chip accommodation, while the tail portion has a smaller cross-section optimized for stiffness and precision hole drilling. This local differentiation resolves the contradiction between chip removal capacity and hole precision.
Solution Approach 2:
The patent introduces variation along the longitudinal dimension of the drill body, creating a gradient in cross-sectional area from head to tail. This dimensional change enables the drill body to simultaneously provide large chip flute capacity at the head and high stiffness at the tail, resolving the contradiction between chip removal and precision.
3Manufacturing precision
If the drill body is designed for high stiffness to minimize radial deflection during long hole drilling, then hole quality is improved, but the ability to transport cutting chips from the bottom of the hole deteriorates
Solution Approach 1:
The drill body design implements local quality by allocating different cross-sectional sizes to different functional zones. The head portion with larger cross-section is optimized for chip transportation, while the tail portion with smaller cross-section provides the stiffness needed for high-quality hole drilling with minimal radial deflection.
Solution Approach 2:
The patent resolves the contradiction by varying the cross-sectional area along the longitudinal dimension of the drill body. The area ratio between head and tail cross-sections is optimized to balance chip transportation capability and structural stiffness, enabling both high hole quality and effective chip removal.
Data Source
AI summary
A drill body and a drill are disclosed. The drill body has a rotational axis and includes a peripheral chip flute extending along a periphery of the drill body. A peripheral chip flute cross-section has a centre line extending in a plane extending perpendicularly to the rotational axis, and through the rotational axis. The peripheral chip flute cross-section has a radially inner side extending perpendicularly to the centre line, and first and second lateral sides connecting to the radially inner side. The radially inner side has a length L1 within a range of L1=0.95×D/4 to L1=1.2×D/4. Each of the first and second lateral sides has a length LS1, LS2 within a range of D/4 to 1.3×D/4. The first and second lateral sides diverge from each other in a direction radially outwards from the radially inner side.