Asymmetric Cutting Insert Bottom Surface for Small-Diameter Milling
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Solution Overview
Problem
Small-diameter milling tools face challenges in maintaining machining accuracy and durability due to reduced wall thickness and uneven cutting resistance, leading to potential displacement and vibration of cutting inserts, especially at corner cutting edges.
Innovation Solution
A cutting insert design featuring a rake face, bottom surface, and circumferential side surface with strategically formed ridgelines and side surfaces that provide increased contact area and thickness at critical cutting edges, enhancing stability and rigidity, and incorporating a through hole for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bottom surface is formed in a V shape to prevent displacement, then the cutting insert is securely fixed, but the contact area is approximately halved leading to reduced restraint force
Solution Approach 1:
The patent applies local quality by creating an asymmetric bottom surface where the first bottom surface has a larger area than the second bottom surface. This non-uniform distribution concentrates the contact area specifically under the corner cutting edge, providing enhanced restraint force exactly where the cutting conditions are strictest and displacement risk is highest, rather than distributing area uniformly.
Solution Approach 2:
The patent employs asymmetry by designing the bottom surface with unequal divisions - the first bottom surface extends farther from the virtual intersection line than the second bottom surface. This asymmetric configuration optimizes the contact area distribution to match the asymmetric loading conditions, particularly reinforcing the corner cutting edge region that experiences more severe cutting forces.
2Manufacturing precision
If the tool diameter is decreased for precision machining, then the wall thickness decreases, but the structural strength and rigidity are reduced
Solution Approach 1:
The patent applies local quality by concentrating the increased thickness specifically at the corner cutting edge region through the asymmetric bottom surface design. The first bottom surface creates a larger contact area that reinforces the insert body at the critical corner region, providing localized strength enhancement exactly where needed without increasing the overall tool diameter or wall thickness elsewhere.
3Strength
If the radial rake becomes negative to increase wall thickness, then the wall thickness increases, but the bottom surface becomes an outward slope generating sliding force
Solution Approach 1:
The patent applies local quality by creating different bottom surface characteristics at different locations. The first bottom surface under the corner cutting edge has a larger area and different inclination than the second bottom surface, providing localized reinforcement and optimized friction characteristics at the critical corner region where sliding force would be most harmful.
Data Source
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AI summary
A cutting insert suitable for a small-diameter milling tool is provided. A cutting insert (10) has a rake face (20), a bottom surface (30), a circumferential side surface (40), and a through hole (19). A first ridgeline (R1) at which the rake face and the circumferential side surface intersect each other includes a first main cutting edge (11), and a first corner cutting edge (12) connected to a tip (11F) of the first main cutting edge. The bottom surface includes a first bottom surface (31) that comes closer to the rake face gradually toward a side at which the first main cutting edge is located when viewed from a central axis (O) of the through hole, and a second bottom surface (32) that comes closer to the rake face gradually toward a side opposite to the first main cutting edge when viewed from the central axis. A distance (W1, W2) between a virtual intersection line (M), at which a first virtual surface (K) formed by extending the first bottom surface and a second virtual surface (L) formed by extending the second bottom surface intersect each other, and the first main cutting edge decreases from a tip side, at which the tip of the first main cutting edge is located, toward an end side, at which an end (11R) opposite to the tip is located, in an extending direction of the first main cutting edge.