Drill Thinning Groove Structure for Smooth Chip Discharge
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Solution Overview
Problem
The existing drill designs face challenges in efficiently discharging chips generated 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 chips to get caught.
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, to smoothly discharge chips without them becoming caught, reducing cutting resistance and ensuring stable chip formation.
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 deteriorated chip discharge performance
Solution Approach 1:
The invention replaces the V-shaped thinning root portion with a circular arc groove having a rounded cross-section. This curvature modification eliminates sharp corners where chips would get caught, enabling smooth chip flow from the thinning face through the gash face to the discharge groove, thereby resolving the contradiction between manufacturing simplicity and chip discharge performance.
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 stress concentration and breakage
Solution Approach 1:
The invention optimizes the radius of curvature parameter of the circular arc groove to a specific range (0.01D to 0.03D). This parameter control ensures the groove is deep enough to prevent chip entrapment and improve discharge performance, while maintaining sufficient thinning edge thickness to avoid stress concentration and breakage, thus resolving the contradiction between chip discharge performance and strength.
3Productivity
If the circular arc groove is made deeper to improve chip discharge, then chip discharge performance is improved, but the thinning edge thickness decreases leading to stress concentration
Solution Approach 1:
The invention establishes an optimal radius of curvature range (0.01D to 0.03D) for the circular arc groove that balances chip discharge performance and thinning edge strength. This controlled parameter ensures the groove provides sufficient chip discharge capability while maintaining adequate material thickness to prevent stress concentration and breakage, resolving the contradiction between productivity and reliability.
Data Source
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.