Drill Cutting Edge Segmentation for Low-Angle Positioning
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Solution Overview
Problem
Conventional drills are inadequate for drilling holes at low angles, particularly in medical contexts like drilling into bones, as they tend to kick the bone surface when the drill axis is angled, making it difficult to position and start drilling accurately.
Innovation Solution
A drill design with a tip cutting edge having a smaller point angle than the main cutting edge, allowing for precise positioning and starting of drilling without contact, and a main cutting edge with progressively decreasing point angles to facilitate low-angle drilling without interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the main cutting edge has a large point angle for efficient drilling, then drilling efficiency is improved, but the drill cannot be positioned accurately at low approach angles
Solution Approach 1:
The cutting edge is divided into two distinct segments: a tip cutting edge with a smaller point angle (e.g., 30-60 degrees) for positioning and initial drilling, and a main cutting edge with a larger point angle (e.g., 60-90 degrees) for efficient material removal. This segmentation allows each segment to perform its specific function optimally without compromise.
Solution Approach 2:
The tip cutting edge performs preliminary action by creating an initial pilot hole or indentation at the drilling position before the main cutting edge engages. This preliminary positioning action ensures accurate placement and prevents the main cutting edge from contacting the bone surface at low approach angles.
2Productivity
If the drill is designed for high-angle drilling with a conventional cutting edge, then drilling efficiency is maintained, but positioning at low angles becomes difficult due to surface contact
Solution Approach 1:
Different portions of the cutting edge are given different geometric properties: the tip portion has a smaller point angle providing a sharper, more localized cutting action for positioning, while the main portion has a larger point angle optimized for efficient material removal. This local differentiation of geometric quality enables both precise positioning and efficient drilling.
3Adaptability or versatility
If the point angle decreases continuously from tip to rear end, then reaming function is achieved, but positioning accuracy at low angles is compromised
Solution Approach 1:
Rather than a continuous gradient, the cutting edge is segmented into distinct zones: a tip zone with smaller point angle for positioning, and a main zone with larger point angle for drilling and reaming. This segmentation preserves positioning accuracy while maintaining the versatility to perform reaming through the main cutting edge's geometry.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A drill (1) includes a tip cutting edge (9) provided at a tip end thereof and a main cutting edge (10) continuous to a rearward of the tip cutting edge (9). A point angle of the tip cutting edge (9) is a predetermined acute angle. A point angle of the main cutting edge (10) decreases from a front end toward a rear end of the main cutting edge. A point angle at the front end of the main cutting edge (10) is an acute angle greater than the point angle of the tip cutting edge (9).