Concave Turning Insert Geometry for Low-Depth Chip Control
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Solution Overview
Problem
Existing turning inserts face challenges in achieving desirable chip breaking and tool life when cutting metals like low carbon steels at low depths of cut, often requiring smaller nose radii, higher feeds, or expensive coolant systems, which compromise surface finish or insert longevity.
Innovation Solution
A turning insert design featuring cutting edges that subtend an angle of 75-85°, with a concave corner cutting edge and a depression on the top surface, improving chip control and reducing flank wear by smoothing transitions and enhancing chip breaking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a smaller nose radius is chosen to improve chip breaking at low depth of cut, then chip shape is improved, but the life of the turning insert decreases
Solution Approach 1:
The invention applies local quality by creating a depression specifically at the corner cutting edge region while maintaining the rest of the insert geometry. This localized modification improves chip breaking at low depth of cut without requiring a smaller nose radius, thereby preserving insert life while achieving desirable chip shape.
Solution Approach 2:
The depression is pre-formed on the insert before machining begins. This preliminary structural modification prepares the chip flow path in advance, enabling effective chip breaking at low depth of cut conditions without needing to change the nose radius or apply other modifications during operation.
2Shape
If a higher feed is chosen to improve chip breaking, then chip shape is improved, but the machined surface finish is reduced
Solution Approach 1:
The depression is localized specifically at the corner cutting edge area, creating a chip breaking zone that does not interfere with the surface generation by the main cutting edge. This allows higher feed rates to be used for improved chip breaking while maintaining good surface finish on the machined workpiece.
3Shape
If high pressure coolant is used to break chips, then chip breaking is improved, but expensive investments are required
Solution Approach 1:
The depression structure on the insert itself performs the chip breaking function without requiring external high-pressure coolant systems. The geometric feature creates chip curling and breaking through its own structure, making the chip breaking capability inherent to the tool rather than dependent on expensive auxiliary systems.
4Shape
If the first surface is extended to improve chip breaking, then chip shape is improved, but the transition points may create stress concentrations
Solution Approach 1:
The depression is designed with curved surfaces and smooth transitions rather than sharp angles. This curvature eliminates stress concentration points that would otherwise form at sharp transitions, maintaining insert strength while still achieving effective chip breaking through the extended first surface geometry.
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A turning insert (1) comprising a top surface (2), an opposite bottom surface (3), a side surface (4) connecting the top and bottom surfaces (2, 3), a cutting edge (15) formed at an intersection between the top surface (2) and the side surface (4). The cutting edge (15) comprising a corner cutting edge (5), a first cutting edge (6) and a second cutting edge (7). The top surface (2) comprises a first surface (13) in the form of a depression, which borders to at least a major portion of the corner cutting edge (5). The first and the second cutting edges (6, 7) subtend an angle θ which is 75 - 85°. At least a part of the corner cutting edge (5) is concave in a front view.