Radius End Mill Corner Gash Geometry for Smooth Chip Flow
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Solution Overview
Problem
Radius end mills with small rake angles on the corner R cutting edge suffer from degraded cutting sharpness, high cutting resistance, and potential chip clogging or breakage due to stepped or edged portions, leading to inefficient processing and rough machined surfaces.
Innovation Solution
A radius end mill design featuring a corner gash with a controlled axial rake angle of 5 to 20 degrees and a recessed corner gash that prevents stepped portions, improves cutting sharpness, and ensures smooth chip flow by maintaining a continuous rake face, reducing the likelihood of chipping and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gash is formed on the corner R cutting edge, then chip removal is improved, but the rake angle becomes small and cutting sharpness is degraded
Solution Approach 1:
The patent applies different rake angles to different regions of the corner R cutting edge. The axial rake angle is specifically controlled to be 5 to 20 degrees in the region where the corner gash is formed, while other regions may have different rake angles. This local differentiation allows the gash to effectively remove chips while maintaining sufficient cutting sharpness in the critical cutting zone.
2Force
If the gash is too small, then cutting resistance is reduced, but the cutting edges are not smoothly connected and stepped portions are formed causing chip clogging
Solution Approach 1:
The corner R cutting edge inherently provides a curved, continuous transition between the end cutting edge and outer peripheral cutting edge. The corner gash is designed to follow this curvature, ensuring smooth connection without abrupt changes or stepped portions. This curved geometry maintains continuous chip flow while managing cutting resistance.
3Productivity
If the rake angle is increased to improve cutting sharpness, then lateral feed machining efficiency improves, but the end cutting edge becomes more susceptible to abrasive wear
Solution Approach 1:
The patent optimizes the axial rake angle parameter to a specific range of 5 to 20 degrees in the corner R cutting edge region. This parameter optimization balances cutting sharpness for efficient lateral feed machining with sufficient edge strength to resist abrasive wear, avoiding both too shallow and too steep rake angles.
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
[Object] To provide a radius end mill that prevents a stepped or edged portion from being formed on the cutting edge at the connection between the corner R cutting edge and the outer peripheral cutting edge, has a good cutting sharpness, and improves a surface roughness on the machined surface. [Solution] A radius end mill 20 includes a tool body 1 that rotates around a center axis O; a series of a plurality of cutting edges 5 composed of an end cutting edge 2 disposed at a distal end of the tool body 1, an outer peripheral cutting edge 4 disposed on an outer periphery of the tool body 1, and a corner R cutting edge 3 which extends between the end cutting edge 2 and the outer peripheral cutting edge 4; a rake face 6 of the end cutting edge 2, the corner R cutting edge 3 and the outer peripheral cutting edge 4; a chip removal flute 7 which extends at the back of the rake face 6; and a corner gash 8 disposed adjacent to the corner R cutting edge 3 of the rake face 6, wherein the corner gash 8 in a planar shape has an edge, part of which is located at the center portion of the corner R cutting edge 3, and an axial rake 2 at an end portion on the side of the end cutting edge 2 which is in contact with the corner gash 8 on the corner R cutting edge 3 is in the range of 5 to 20 degrees.