Multi-Corner Cutting Insert Geometry for Better Chip Discharge
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Solution Overview
Problem
Cutting inserts with multiple corners face challenges in chip discharge performance due to the shape of their cutting edges, leading to chips being caught between the flank and the work material, especially when the space between the flank and the finished surface is small.
Innovation Solution
The cutting insert design features a second cutting edge that retreats further towards the center with a larger clearance angle than the first cutting edge, creating a larger space for chip discharge, and includes a curved third side surface recessed towards the center, along with a fourth side surface with a smaller clearance angle to enhance mounting accuracy and prevent chip accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cutting insert has a large number of corners (e.g., regular octagonal shape), then economic efficiency is improved, but chip discharge performance deteriorates due to monotone cutting edge shapes and small space between flank and finished surface
Solution Approach 1:
The cutting insert employs asymmetric cutting edge configurations where the second cutting edge is positioned closer to the central part than the first cutting edge, and the second side surface has a larger clearance angle than the first side surface. This breaks the monotone symmetry of regular polygonal shapes, creating varied chip discharge paths and larger clearance spaces that improve chip evacuation while maintaining multiple corners for economic efficiency
Solution Approach 2:
Different regions of the cutting insert are given different geometric properties: the first side surface has a smaller clearance angle suitable for certain cutting conditions, while the second side surface has a larger clearance angle for improved chip discharge. The third side surface is recessed to create additional clearance space locally where needed, allowing optimized performance in different areas of the same tool
2Manufacturing precision
If the space between the flank and the finished surface is small, then the cutting insert can achieve better surface finish, but chip discharge performance deteriorates as chips get caught in the space
Solution Approach 1:
The third side surface is designed to be recessed toward the central part of the cutting insert, creating a stepped or multi-level flank structure. This adds a dimensional variation to the otherwise planar flank surface, generating additional clearance space in the radial direction that allows chips to escape without compromising the close tolerance needed for good surface finish
Data Source
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AI summary
Provided is a cutting insert, which has excellent chip discharge performance even when formed with multiple corners superior in economic efficiency. A first ridgeline (R1) at which an upper surface (5) and a circumferential side surface (7) intersect each other includes a plurality of corners (A, B, C, D, E, F, G, H) disposed at equal intervals and a plurality of main cutting edges (50) disposed one by one between the corners adjacent to each other. A distance between the corners adjacent to each other is equal to or less than 60% of the diameter of a circle inscribed within the ridgeline. The main cutting edges includes a first cutting edge (51) that is linearly formed and a second cutting edge (52) that is linearly formed. The length (L2) of the second cutting edge is equal to or less than half the length (L1) of the first cutting edge and is positioned closer to a center side of the cutting insert than an extension line of the first cutting edge is. The circumferential side surface includes a first side surface (71) facing the first cutting edge and a second side surface (72) facing the second cutting edge. A clearance angle (α) of the first side surface is smaller than that (β) of the second side surface.