Curved-Honing Drill Insert for Chipping and Welding Resistance
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Solution Overview
Problem
Cutting edge replacement type drills face challenges in ensuring sufficient chipping resistance and preventing damage due to welding, particularly when drilling stainless steel, as the existing designs suffer from increased cutting load and resistance near the rotation axis, leading to weakened cutting blades and potential damage from welding scraps.
Innovation Solution
A drill insert with a polygonal plate-shaped body featuring a rake face and flank face intersection, where the cutting blade includes a honing face with first and second convex curved faces, and a breaker groove with an inclined bottom surface, positioned to enhance chipping resistance and reduce cutting heat, ensuring strength and preventing welding damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a flat rake face is formed between the cutting blade and chip breaker in the inner circumferential side drill insert, then the structure is simple, but the strength of the cutting blade is insufficient and chipping resistance cannot be ensured
Solution Approach 1:
The patent applies curvature by forming a convex curved face on the rake face between the cutting blade and chip breaker, replacing the conventional flat surface. This curved geometry increases the lip angle of the cutting blade, thereby enhancing its strength and chipping resistance while maintaining structural simplicity, effectively resolving the technical contradiction between structural simplicity and cutting blade strength.
2Strength
If the negative land is formed on the cutting blade on the rotation axis to ensure strength, then the cutting blade strength is ensured, but the cutting resistance increases and cutting heat increases leading to welding damage
Solution Approach 1:
The patent forms a convex curved face on the rake face that gradually rises from the flank face toward the rotation axis, creating a curved surface rather than a flat negative land. This curvature increases the lip angle progressively, enhancing cutting blade strength while reducing cutting resistance and cutting heat compared to conventional negative lands, thereby preventing welding damage.
Solution Approach 2:
The patent changes the geometric parameters of the rake face by forming a convex curved face with specific curvature radius (R1) that is larger than the curvature radius (R2) of the honing face. This parameter change optimizes the lip angle distribution, reducing cutting resistance and cutting heat while maintaining sufficient cutting blade strength, thus preventing welding damage.
3Strength
If the honing face with large curvature radius is formed on the rake face side, then the cutting blade strength is ensured, but the chipping resistance may be insufficient
Solution Approach 1:
The patent forms a convex curved face on the rake face with curvature radius R1 that is specifically designed to be larger than the curvature radius R2 of the honing face. This dual-curvature design ensures that the honing face provides sufficient strength while the convex curved face on the rake face enhances chipping resistance by increasing the lip angle, effectively resolving the contradiction between strength and chipping resistance.
Data Source
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AI summary
An object of the present invention is to ensure sufficient chipping resistance with respect to a large cutting load, cutting resistance, and welding. Provided is a drill insert which is detachably attached to a distal portion of a drill body which is rotated around an axis, in which a polygon face of a polygonal plate-shaped insert body (1) is a rake face (2), a side face disposed around the rake face (2) is a flank face (3), a cutting blade (4) is formed on a ridge portion in which the rake face (2) and the flank face (3) intersect each other, the cutting blade (4) includes a honing face (9) which is formed on a first cutting blade portion (4A) continuous with at least one end portion of the cutting blade (4) and which gradually rises from the flank face (3) toward the rake face (2), the honing face (9) includes a first convex curved face (9A) continuous with the rake face (2) and a second convex curved face (9B) continuous with the flank face (3), and in a cross section orthogonal to the cutting blade (4), a curvature radius (R1) of the first convex curved face (9A) is larger than a curvature radius (R2) of the second convex curved face (9B).