Double-Sided Milling Insert Geometry for Gentle Chip Formation
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Solution Overview
Problem
Double-sided cutting inserts for milling face milling operations face challenges in achieving a stable and gentle cutting process due to restrictions in design freedom imposed by their double-sided form, leading to issues with effective raking angles, clearance angles, and chip formation, particularly when tilted for protection of inactive cutting edges.
Innovation Solution
A double-sided cutting insert design with a fourfold rotational symmetry, featuring alternately arranged main cutters and face cutters, positive nominal face clearance angles, and negative nominal main clearance angles, allowing for a slight negative axial installation angle and a more negative radial installation angle, resulting in a very great positive effective axial angle for gentle material removal and optimal chip discharge, while protecting inactive cutters from wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cutting insert is tilted with large negative axial and radial installation angles to protect inactive cutting edges, then the protection of inactive cutters is improved, but the effective cutting forces and chip formation deteriorate
Solution Approach 1:
The patent applies different clearance angle characteristics to different regions of the cutting insert. The face clearance surfaces have positive clearance angles that increase toward the axis of symmetry, while the main clearance surfaces have negative clearance angles that increase away from the axis of symmetry. This local differentiation allows optimal protection of inactive cutters in the face cutter region while maintaining good chip formation and cutting forces in the main cutter region.
Solution Approach 2:
The patent changes the clearance angle parameters across different surfaces and regions. The face clearance angles range from 5° to 15° depending on distance from the axis of symmetry, while main clearance angles range from -5° to -15° depending on distance from the axis of symmetry. These parameter variations enable simultaneous achievement of cutter protection and good cutting performance.
2Productivity
If the cutting insert is designed with double-sided form for efficient use, then the productivity is improved, but the design freedom for raking angles and clearance angles deteriorates
Solution Approach 1:
The patent introduces asymmetry in the clearance surface design relative to the cutting edges. The face clearance surfaces are arranged asymmetrically with positive angles that vary with distance from the axis of symmetry, while main clearance surfaces have asymmetric negative angles. This asymmetric design within the symmetric double-sided structure provides the needed design freedom to optimize both productivity and cutting performance.
3Stability of the object's composition
If the main clearance surfaces extend away from the axis of symmetry, then the negative nominal main clearance angles are achieved for stable cutting wedge, but the design flexibility deteriorates
Solution Approach 1:
The patent applies different clearance angle characteristics to different regions. Main clearance surfaces have negative angles that increase away from the axis of symmetry, providing stable cutting wedge for material removal. Face clearance surfaces have positive angles that increase toward the axis of symmetry, providing protection for inactive cutters. This local quality differentiation maintains design flexibility while achieving stability where needed.
Data Source
AI summary
A double-sided cutting insert for milling has a first cutting edge formed at a transition from a top side to a circumferential lateral surface and a second cutting edge formed at a transition from a bottom side to the circumferential lateral surface. A reference plane (R) runs normal to an axis of symmetry (S). The cutting edges have main cutting edge portions and face cutting edge portions arranged in alternation, which extend between raised cutting corners and lowered cutting corners. The circumferential lateral surface has face free surfaces, which extend along the face cutting edge portion and which approach the axis of symmetry (S) with increasing distance from the associated face cutting edge portion. The circumferential lateral surface has main free surfaces, which extend along the main cutting edge portion and which move farther away from the axis of symmetry with increasing distance from the associated main cutting edge portion.