Drill Chisel Edge Geometry for Deep Hole Chip Evacuation
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Solution Overview
Problem
Deep hole drilling with thicker web thickness leads to shallower flutes, reducing the pulling force of chips and increasing the likelihood of chip clogging, as the chips generated by the chisel edge are not effectively fragmented.
Innovation Solution
A drill design with concavely curved main cutting edges and a specific helix angle configuration for the flutes, along with a minor cutting edge structure that includes first and second chisel edges with different inclination angles, enhances chip fragmentation and evacuation, even with thicker web thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the web thickness of the drill body is made thicker to improve durability, then the durability is improved, but the flute becomes shallower, reducing the pulling force of chips and increasing the likelihood of chip clogging
Solution Approach 1:
The patent changes the geometric parameters of the cutting edges, specifically setting the first inclination angle of the first chisel edge to be greater than the second inclination angle of the second chisel edge. This parameter change optimizes chip fragmentation while maintaining the thicker web thickness for durability, resolving the contradiction between durability and chip evacuation.
2Reliability
If the flute becomes shallower due to thicker web thickness, then the durability is improved, but the pulling force of chips becomes smaller, reducing chip fragmentation
Solution Approach 1:
The patent applies parameter changes by optimizing the inclination angles of the chisel edges. The first chisel edge has a greater first inclination angle than the second inclination angle of the second chisel edge, creating effective chip fragmentation even with shallower flutes resulting from thicker web thickness.
Solution Approach 2:
The patent applies local quality by giving different inclination angles to different parts of the chisel edge. The first chisel edge portion has a greater inclination angle than the second chisel edge portion, creating localized variations in chip cutting and fragmentation characteristics that compensate for the reduced flute depth.
Data Source
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AI summary
A drill according to an embodiment of the present invention has a pair of main cutting edges positioned at a front end of a drill body, a pair of first chisel edges each extending from the pair of main cutting edges toward a rotation axis, and a second chisel edge positioned between the pair of first chisel edges and intersecting with the rotation axis of the drill body. When viewing a locus of rotation of the pair of first chisel edges and a locus of rotation of the second chisel edge in a cross section taken so as to include the rotation axis, the respective locus of rotation of the pair of first chisel edges have a rectilinear shape, and respective imaginary straight lines obtained by extending the locus of rotation of the pair of first chisel edges toward the rotation axis are positioned further to a rear end side of the drill body than the locus of rotation of the second chisel edge.