Cutting Insert Positive Rake Angle Chip Breaker
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Solution Overview
Problem
Cutting inserts with a 0° rake angle experience high cutting forces and crater wear, and struggle to achieve sufficient cutting-edge strength and chip breaking performance when processing difficult-to-cut materials like hardened steel, limiting their practical use.
Innovation Solution
A cutting insert design featuring a superhard sintered body with a positive rake angle, an arc cutting edge, and a chip breaker structure that includes a projection, first and second breaker walls, and a truncated portion to enhance edge strength and chip breaking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a 0° rake angle is used in the cutting insert, then the cutting edge strength is maintained, but the cutting force increases and crater wear occurs
Solution Approach 1:
The patent applies local quality by providing different rake angles in different regions: the main cutting edge area has a positive rake angle (10° to 30°) to reduce cutting force, while the chip breaker formation area maintains structural integrity. This localized differentiation allows the cutting insert to simultaneously achieve reduced cutting force and maintained edge strength where needed.
Solution Approach 2:
The patent changes the rake angle parameter from the conventional 0° or negative values to a positive range (10° to 30°). This parameter change directly reduces the cutting force and prevents crater wear while the chip breaker geometry compensates for any potential loss in edge strength through its structural design.
2Strength
If a 0° rake angle is used in the cutting insert, then the cutting edge strength is maintained, but the chip breaking performance deteriorates due to insufficient breaker wall height
Solution Approach 1:
The patent applies local quality by creating a localized chip breaker structure with projected portions that extend from the cutting edge. These projections form breaker walls at specific locations where chip control is needed, while the rest of the cutting edge maintains its strength-optimized geometry. The breaker wall height is locally increased to ensure reliable chip breaking without compromising overall edge strength.
3Force
If a positive rake angle is used in the cutting insert, then the cutting force is reduced and chip breaking performance improves, but the cutting edge strength becomes insufficient for difficult-to-cut materials
Solution Approach 1:
The patent resolves this contradiction by applying local quality: the positive rake angle (10° to 30°) is applied to the main cutting surface to reduce cutting force, while the chip breaker projections and breaker walls are strategically positioned to provide localized structural reinforcement. This allows the cutting edge to have both the reduced force characteristics of a positive rake angle and the strength reinforcement needed for difficult materials.
Solution Approach 2:
The patent employs composite material principles by combining the positive rake angle geometry with a chip breaker structure made of the same superhard material. The composite structure of the cutting insert, with its integrated positive rake angle and chip breaker projections, achieves both reduced cutting force and sufficient edge strength for processing hardened steel and other difficult-to-cut materials.
4Ease of operation
If a positive rake angle is used in the cutting insert, then chip flow is improved, but the breaker wall height becomes insufficient for effective chip breaking
Solution Approach 1:
The patent applies dimensionality change by adding projected portions that extend in a direction perpendicular to the main rake face. These projections create breaker walls that increase in height in the vertical dimension, while the positive rake angle on the main face continues to facilitate smooth chip flow. The chip breaker structure effectively adds another dimensional element to control chip breaking without interfering with the beneficial chip flow characteristics.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An object is to provide a cutting insert that can be designed to have a positive rake angle while ensuring the required cutting-edge strength, so that the cutting force can be reduced, the life can be extended, and the chip breaking performance can be improved. A superhard sintered body (3) is bonded to a corner of a substrate (2), and a cutting edge (5), a rake face (6), and a chip breaker (7) are formed in the superhard sintered body (3). The chip breaker (7) includes, in a plan view of the insert, a projection (7a) that projects from a line that crosses a bisector of the corner toward a tip end (T) of an arc edge (5a) of the cutting edge; a first breaker wall (7b) formed between a top edge (e1 of the projection and the rake face (6); and a second breaker wall (7c) formed between a ridge line (e2) that extends from a base end of the projection (7a) to a side surface of the superhard sintered body (3) and the rake face (6). A ridge line (e3) formed between the rake face (6), which has a positive rake angle, and the side surface of the superhard sintered body (3) is inclined such that a distance to a bottom surface (2c) of the substrate decreases as a distance from the cutting edge (5) increases.