Curved Drill Cutting Edge for Lower Stress and Chatter
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Solution Overview
Problem
Conventional drills experience stress concentration and breakage at the connection portion between the ridge line and the second tip cutting edge, leading to reduced machining accuracy and durability during drilling operations.
Innovation Solution
A drill design featuring a rod-shaped body with a cutting edge configuration that includes a first cutting edge, a second cutting edge, and a third part with a concave curved shape, which reduces stress concentration and enhances machining accuracy and durability by managing radial loads and minimizing chatter vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ridge line and second tip cutting edge are connected at an angle, then the drill structure is simpler to manufacture, but stress concentration occurs at the connection portion leading to breakage
Solution Approach 1:
The patent applies curvature by replacing the angular connection between the ridge line and second tip cutting edge with a curved surface. Specifically, the ridge line connects to the second tip cutting edge through a curved transition zone rather than a sharp angle, which distributes stress more evenly and prevents stress concentration at the connection portion, thereby improving durability while maintaining manufacturability
2Productivity
If the second cutting edge is positioned closer to the outer peripheral surface, then cutting performance is improved, but stress concentration and breakage risk increase
Solution Approach 1:
The patent positions the second cutting edge closer to the outer peripheral surface to improve cutting performance, but mitigates the stress concentration risk by introducing curved surfaces at the connection portions. The curved transition zones between cutting edges and the ridge line distribute mechanical stresses more effectively, allowing the second cutting edge to be optimally positioned for cutting performance without compromising durability
3Ease of manufacture
If conventional drill geometry is used, then manufacturing is simpler, but machining accuracy deteriorates due to diameter reduction and delamination
Solution Approach 1:
The patent introduces curved surfaces in the cutting edge geometry, specifically the concave curved surface on the first tip cutting edge and curved transition zones. These curved features reduce chatter vibration during machining, which in turn prevents delamination of the workpiece surface and maintains hole diameter accuracy, thereby improving machining precision while keeping the overall structure manufacturable
4Device complexity
If the first cutting edge extends straight from the axis, then the structure is simpler, but chatter vibration increases reducing machining accuracy
Solution Approach 1:
The patent replaces the straight extension of the first cutting edge from the axis with a curved configuration. The first tip cutting edge features a concave curved surface that reduces chatter vibration during machining operations. This curved geometry improves machining accuracy by minimizing vibrations without significantly increasing structural complexity
Data Source
AI summary
A drill may include a body extending from a first end toward a second end, and the body may include an outer peripheral surface and a cutting edge. The cutting edge may include a first cutting edge and a second cutting edge. The second cutting edge may be positioned closer to the second end and the outer peripheral surface than the first cutting edge. The second cutting edge may include a first part, a second part and a third part. The second part may be positioned closer to the outer peripheral surface than the first part and may be positioned closer to the second end as close to the first part. The third part may be positioned closer to the first cutting edge than the first part and may be positioned closer to the second end as close to the first part.