End Mill Transition Edge Geometry for Reduced Wear and Chipping
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Solution Overview
Problem
Conventional end mills are prone to wear and damage, particularly at the corner portion where the front and side cutting edges meet, leading to notch wear and chipping.
Innovation Solution
The end mill tool features a cutting head with cutting teeth that have a transition cutting edge with a convex clearance surface and a positive axial rake angle equal to or less than the helix angle of the chip flute, which helps to avoid the creation of new sharp corners and enhances the tool's resistance to wear and chipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chamfer is provided at the transition of the front edge to side edge to remove sharp corners, then corner damage is reduced, but a new sharp corner is created on the front cutting edge radially inward from the periphery
Solution Approach 1:
The invention applies curvature by providing a convex clearance surface along the transition cutting edge instead of a flat chamfer. This convex curvature eliminates sharp corners while maintaining a continuous, smooth transition between the front and side cutting edges, preventing stress concentration and chip hooking at the transition zone.
Solution Approach 2:
The invention applies different geometric properties to different regions of the cutting edge. The clearance surface is specifically designed to be convex only at the transition cutting edge region, while other portions of the cutting edge maintain their conventional geometry. This localized application of convexity addresses the specific problem at the transition zone without affecting other cutting edge functions.
2Productivity
If the axial rake angle is increased to improve cutting performance, then cutting efficiency increases, but the transition cutting edge becomes more prone to wear and chipping
Solution Approach 1:
The invention optimizes the axial rake angle parameter at the transition cutting edge by setting it equal to or less than the helix angle. This parameter adjustment creates a more favorable stress distribution and reduces the mechanical load on the transition edge, thereby improving its resistance to wear and chipping while maintaining acceptable cutting efficiency.
3Reliability
If a convex clearance surface is provided along the transition cutting edge, then wear and chipping resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The convex clearance surface is applied only to the transition cutting edge region rather than the entire cutting edge or tool body. This localized application minimizes the additional manufacturing complexity while achieving the primary objective of improving transition edge durability. The rest of the tool geometry can be manufactured using conventional methods.
Data Source
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AI summary
The present invention relates to an end mill tool for metal cutting comprising a cutting head (2), which is rotatable around a longitudinal axis (4) in a direction of rotation (6). The cutting head (2) comprises a plurality of cutting teeth (7), which each has a cutting edge formed at an intersection of a respective rake surface (8) and a respective clearance surface (9), and a plurality of chip flutes (13), which, rotationally in front of a respective one of the plurality of cutting teeth (7), each extends axially rearward from the front end (3), and which each has a respective helix angle α. The cutting edge of each of the plurality of cutting teeth (7) comprises at the front end (3), a front cutting edge (10) extending radially outward from a central region at the longitudinal axis (4) and a transition cutting edge (11) extending from the front cutting edge (10) to a side cutting edge (14). The clearance surface (9) of each of the cutting teeth (7) along the transition cutting edge (11), in a direction of the extension of the transition cutting edge (11), is convex. The rake surface (8) of each of the plurality of cutting teeth (7) has an axial rake angle β. Along the transition cutting edge (11), the axial rake angle β is positive, and equal or less than the helix angle α at the front end of the chip flute (13) which is rotationally in front thereof.