Drill Point Gash Groove Geometry for Smooth Chip Evacuation
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Solution Overview
Problem
Existing drills face challenges in efficiently discharging chips near the chisel, leading to potential deterioration in chip discharge performance and increased cutting resistance due to the thinning root portion's V-shaped cross-section, which can cause chip entrapment.
Innovation Solution
The drill features a circular arc groove connecting the gash face and the thinning face, with a radius of curvature between 0.01D and 0.03D, and a gash furrow distance between 0.02D and 0.04D, ensuring smooth chip discharge without clogging and reducing cutting resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a V-shaped thinning root portion is used to connect the rake face and gash face, then the structure is simple and easy to manufacture, but chips get caught in this portion causing deterioration of chip discharge performance
Solution Approach 1:
The patent applies curvature by replacing the V-shaped thinning root portion with a rounded configuration. Specifically, the thinning root portion is formed with a radius of curvature R where 0.01D ≤ R ≤ 0.05D (D being the drill diameter), creating a smooth curved transition between the rake face and gash face. This curved geometry prevents chip entrapment while maintaining manufacturing feasibility through standard grinding or machining processes.
2Productivity
If the gash portion extends to the outer peripheral surface with larger radius of curvature, then chip discharge performance is improved, but the thinning edge becomes too thin causing breakage
Solution Approach 1:
The patent employs parameter optimization by establishing specific ranges for critical dimensions. The radius of curvature of the thinning root portion is constrained to 0.01D ≤ R ≤ 0.05D, and the distance from the outer peripheral surface to the gash portion end is limited to 0.01D ≤ L ≤ 0.05D. These parameter specifications ensure adequate thinning edge thickness for strength while maintaining effective chip discharge geometry.
Data Source
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AI summary
Two discharge grooves (4) are formed in a drill (1). A cutting edge (5) is formed on a ridge section between an inner face (41) that faces a rotation direction (T) side of the discharge groove (4), and a flank (6). A thinning edge (7) is formed from an inner end (51) of the cutting edge (5) to the side of a chisel (9), by thinning processing, and further, a gash portion (8) is formed from an inner end (72) of the thinning edge (7), the gash portion extending in a circular arc shape and being connected to the discharge groove (4) further to an inner side in the radial direction than an outer peripheral surface (31). A circular arc groove (10) is formed in a section connecting a thinning face (71) and a gash face (81). The chips being cut by the thinning edge (7) are scooped up to the gash portion (8), are curled, and are discharged to the discharge groove (4). The chips are not likely to become caught by being provided with the circular arc groove (10). Since the gash portion (8) connects to the discharge groove (4) further to the inner peripheral side than the outer peripheral surface (31), the chips are cut relatively small.