Drill Cutting Edge Convex Ridge Curvature Design
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Solution Overview
Problem
Conventional edge tip treatments for drills, such as chamfering, fail to adequately suppress damage and wear in the outer peripheral portion of the cutting edge, particularly at intersecting positions, leading to insufficient chipping resistance and premature wear.
Innovation Solution
A negative land is provided on the rake face with specific curvature radii for convex ridge lines at intersecting positions between the negative land, flank face, and margin, which reduces fine chipping and wear by forming rounded convex faces in a longitudinal rectangular cross section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional edge tip treatment (chamfering) is applied to reinforce the cutting edge, then the edge tip strength is improved, but the outer peripheral portion becomes susceptible to fine chipping and wear
Solution Approach 1:
The invention applies different surface qualities to different regions of the cutting edge. The outer peripheral portion receives a curved face treatment with specific radius ratios (0.5-2.0 times the inner radius) to enhance chipping resistance, while the inner peripheral portion maintains the standard chamfered flat surface. This localized differentiation allows each region to be optimized for its specific functional requirements.
Solution Approach 2:
The invention introduces curved faces with specific radius ratios at the outer peripheral portion of the cutting edge. The first curved face has a radius of curvature that is 0.5-2.0 times the radius of the second curved face, creating a graduated curvature transition. This spherical/curved geometry distributes stress more evenly and prevents the concentration of microvibrations that cause chipping.
2Strength
If the cutting edge is chamfered to dull the edge tip, then edge reinforcement is achieved, but damage to the outer peripheral portion cannot be suppressed
Solution Approach 1:
The invention applies different surface treatments to different regions: the outer peripheral portion receives curved face treatment with enhanced radius ratios to prevent damage, while the inner peripheral portion maintains standard chamfering for reinforcement. This localized approach ensures each region addresses its specific vulnerability.
Solution Approach 2:
The curved face treatment with increased radius of curvature at the outer peripheral portion acts as a pre-cushioning measure against microvibrations and impacts before they can cause damage. The gradual curvature transition prepares the edge to absorb and distribute mechanical stresses, preventing the initiation of chips and wear.
3Ease of manufacture
If standard chamfering is used, then manufacturing simplicity is maintained, but chipping resistance in the outermost peripheral portion is insufficient
Solution Approach 1:
The invention applies the complex curved face treatment only to the outer peripheral portion where chipping resistance is critical, while the inner peripheral portion maintains simple standard chamfering. This selective application balances manufacturing complexity with functional performance, focusing enhanced treatment only where needed.
Data Source
AI summary
In a drill, a negative land is provided on a rake face, and a ridge line at an intersecting position of the negative land and a flank face, a ridge line at an intersecting position of the flank face and a margin, and a ridge line at an intersecting position of the negative land and the margin are convex faces in a longitudinal rectangular cross section. When a curvature radius of the convex face of a first ridge line at the intersecting position of the flank face and the negative land is 1, at curvature radius of the convex face of a second ridge line at the intersecting position of the flank face and the margin is 0.8 to 1.5 times the curvature radius of the first ridge line, and a curvature radius of the convex face of a fourth ridge line at the intersecting position of the negative land and the margin is 1.5 to 3.0 times the curvature radius of the first ridge line.