Ceramic Radius End Mill Rake Face Layout to Prevent Corner Chipping
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Solution Overview
Problem
Conventional radius end mills made of ceramic experience chipping or damage on corner R cutting edges during cutting of heat-resistant alloys due to high cutting loads, despite the use of corner R rake faces to prevent partial breakage.
Innovation Solution
The end mill body features a chip ejection groove, a peripheral cutting edge, an end cutting edge rake face, and a corner R cutting edge that is arcuately convex, with a corner R rake face formed between the end cutting edge rake face and the chip ejection groove, ensuring the corner R rake face does not exist on the end-cutting-edge side but is present on the peripheral-cutting-edge side, and a positive axial rake to reduce adhesion and improve chip ejectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a corner R rake face is provided on the end cutting edge to prevent partial breakage, then the strength of the corner R cutting edge is improved, but chipping still occurs at the starting point of the corner R rake face due to large cutting loads on the end cutting edge
Solution Approach 1:
The invention applies different rake face configurations to different regions of the corner R cutting edge. Specifically, the corner R rake face is designed to be present only in the region from the midpoint of the corner R cutting edge to the peripheral cutting edge, while the region from the end cutting edge to the midpoint has a different configuration (end cutting edge rake face). This local differentiation allows the corner R cutting edge to have enhanced strength where needed while avoiding chipping at the high-stress starting point near the end cutting edge.
2Strength
If the corner R rake face extends to the end cutting edge, then the corner R cutting edge is better protected, but the large cutting load on the end cutting edge causes chipping at the starting point of the corner R rake face
Solution Approach 1:
The corner R cutting edge region is segmented into two distinct zones: one from the end cutting edge to the midpoint, and another from the midpoint to the peripheral cutting edge. Each zone is assigned a different rake face configuration - the end cutting edge rake face for the first zone and the corner R rake face for the second zone. This segmentation prevents the concentration of stress at a single starting point while maintaining protective coverage where most needed.
3Temperature
If a ceramic end mill is used for cutting heat-resistant alloys, then high temperature resistance is achieved, but partial breakage occurs on corner R cutting edges due to large cutting loads
Solution Approach 1:
The invention applies localized rake face design to specific regions of the corner R cutting edge. The corner R rake face is positioned only in the region from the midpoint to the peripheral cutting edge, providing localized strength enhancement and chip control where the cutting load is most beneficially directed, while the end cutting edge region maintains its own rake face configuration optimized for that specific zone's cutting conditions.
Data Source
AI summary
In an end mill body made of ceramic, a corner R rake face is formed in such a manner as to contain a point B and at least a region B, not a region A located on a side toward an end cutting edge. In other words, a first end portion of a cutting edge on a peripheral edge portion of the corner R rake face is formed on a peripheral edge of the region B of a corner R cutting edge, and a second end portion of the cutting edge reaches at least the point B. As a result, partial breakage of the corner R cutting edge is unlikely to occur in the course of cutting. That is, since the corner R rake face is formed in such a manner as to start from the first end portion located apart from a point A, which is the intersection of the end cutting edge and the corner R cutting edge, and such that the second end portion reaches the point B, a large cutting load is unlikely to be imposed on the starting point of the corner R rake face. Therefore, the corner R cutting edge is unlikely to be chipped.