End Mill Chisel Gash Design for Cutting Resistance
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Solution Overview
Problem
Existing end mills experience high cutting resistance near the rotational axis, leading to flaws and chip clogging due to uneven flute capacities and stress concentration at the chisel portion.
Innovation Solution
The end mill design features a chisel portion with a gradual thickness decrease from the outer periphery to the rotational axis, incorporating first and second gashes that reduce flute capacity differences and stress, along with a specific ratio of gash lengths and angles to enhance chip dischargeability and prevent chattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If gash is cut to form chisel portion with thin thickness near rotational axis, then cutting resistance is decreased, but stress concentration occurs causing chipping and flaws
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness distribution of the chisel portion through specific gash dimensions. The first gash has a terminal end positioned at a specific distance from the distal end, and the second gash has its terminal end at a different distance, creating a gradual thickness transition. This parameter optimization reduces cutting resistance while preventing stress concentration that causes chipping.
Solution Approach 2:
The patent implements local quality by creating non-uniform thickness distribution in the chisel portion. The thickness varies locally from the outer periphery toward the rotational axis, with the first gash removing more material than the second gash. This local variation in geometry allows the chisel portion to have different properties at different locations, reducing overall cutting resistance while maintaining structural integrity.
2Productivity
If chisel portion thickness is reduced to decrease cutting resistance, then chip dischargeability improves, but tool life decreases due to increased chipping
Solution Approach 1:
The patent uses parameter changes by optimizing the distances from the distal end to the terminal ends of the first and second gashes. By controlling these dimensional parameters within specific ranges, the patent achieves a balance where chip dischargeability is improved through adequate thickness reduction, while tool life is preserved by preventing excessive thinning that would cause chipping and premature failure.
3Productivity
If gash depth is increased to improve chip dischargeability, then cutting performance improves, but flute capacity becomes uneven causing stress concentration
Solution Approach 1:
The patent applies segmentation by dividing the gash structure into two distinct parts: the first gash and the second gash. Each gash has different dimensions and positioning, with the first gash extending further from the distal end than the second gash. This segmentation allows each gash to perform its function optimally while maintaining overall flute capacity uniformity, preventing stress concentration.
Solution Approach 2:
The patent implements asymmetry by making the first and second gashes non-identical in their dimensions and positioning. The first gash has a terminal end at a specific distance from the distal end, while the second gash has its terminal end at a different distance. This asymmetric design creates balanced flute capacities that prevent stress concentration while improving cutting performance.
Data Source
AI summary
A end mill includes: an end mill body having a rotation axis, the end mill body including a shank portion and a cutting portion with an outer peripheral cutting edge; an end cutting edge including a first cutting edge and a second cutting edge; a first gash opening between the first cutting edge and the second cutting edge; and a second gash located adjacently to the first gash in the rotational direction, and opening to a side closer to the outside peripheral from the chisel portion. A ratio (L1/L2) of a length (L1) from a distal end of the end mill body to a terminal end of the first gash to a length (L2) from the distal end of the end mill body to a terminal end of the second gash, when viewed from a side, is from 0.8 to 1.1.