Cutting Insert Convex Corner Edge Reduces Abrasion

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Solution Overview

Problem

Cutting inserts used for grooving and parting-off operations experience increased cutting resistance due to corner edge abrasion, leading to reduced insert life and compromised machining accuracy and quality, with inefficiencies in forming wide grooves and finish cutting processes.

Innovation Solution

A cutting insert with convex-shaped corner edges having a point of inflection, where the tangent line changes direction, ensures larger clearance and reduced abrasion, and a cutting method that allows continuous cutting during retraction, enhancing machining efficiency and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If corner edges are formed to curve outward and reach side cutting edges, then surface finish is improved, but cutting resistance increases significantly due to abrasion progression

Engineering Contradiction:

Improvesurface finishVSAvoidcutting resistance

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

Instead of curving outward as in conventional designs, the corner edge is designed to curve inward (concave shape) from the front cutting edge toward the side cutting edge. This inversion of the curvature direction reduces the length of abrasion in the longitudinal direction while maintaining surface finish quality, thereby reducing cutting resistance and extending insert life.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The radius of curvature of the corner edge is specifically controlled to be smaller than that of the wiper cutting edge. By changing the curvature parameter, the design achieves a balance between surface finish quality and reduced abrasion length, preventing excessive cutting resistance increase.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If corner edges curve outward to improve surface finish, then machining quality is enhanced, but insert life is reduced due to increased cutting resistance

Engineering Contradiction:

Improvemachining qualityVSAvoidinsert life

Core Design Contradiction:

Manufacturing precisionVSDuration of action of moving object

Solution Approach 1:

The corner edge is designed with a concave curvature (curving inward) rather than convex curvature (curving outward). This inversion reduces the longitudinal abrasion length to less than one-third of conventional designs, significantly reducing cutting resistance increase and extending insert life while maintaining surface finish quality.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The radius of curvature parameter is optimized to be smaller than that of the wiper cutting edge, controlling the abrasion progression rate and extending the functional life of the cutting insert.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If insert body shifts due to increased cutting resistance, then positioning flexibility is improved, but machining accuracy is compromised as side cutting edge digs into machined surface

Engineering Contradiction:

Improvepositioning flexibilityVSAvoidmachining accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The concave corner edge design reduces cutting resistance, preventing insert body shift and maintaining stable positioning. This stability ensures that the side cutting edge does not dig into the machined surface, preserving machining accuracy while allowing positioning flexibility.

Inventive Principle:

Principle #13The other way round (Inversion)

4Adaptability or versatility

If retraction is performed to form wide grooves, then groove width capability is improved, but machining efficiency decreases due to non-cutting movement time

Engineering Contradiction:

Improvegroove width capabilityVSAvoidmachining efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The concave corner edge design enables continuous cutting action during both forward feed and retraction movements. The reduced abrasion and cutting resistance allow the cutting edge to maintain effectiveness throughout the entire reciprocating cycle, eliminating idle non-cutting time and improving machining efficiency while maintaining wide groove capability.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentEP2140959B1Cutting insert, and cutting method

Publication Date: 2016.09.28 MITSUBISHI MATERIALS CORP

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AI summary

A cutting insert, wherein: a cutting edge part having a quadrangular shaped cutting face, which is provided with a pair of side cutting edges extending in a longitudinal direction of an insert body, and a front cutting edge between ends of the side cutting edges that extends in a direction that intersects the longitudinal direction, is formed at an end of the insert body having a bar-shape; and viewed from a direction facing the cutting face perpendicularly to the longitudinal direction, at least one of a pair of corner edges where the side cutting edge and the front cutting edge intersect is formed in a convex shape such that it has a point of inflection at which, after a tangent line that makes contact with the corner edge rotates in a direction extending in the longitudinal direction along the corner edge from the front cutting edge, its direction of rotation changes, and it joins the side cutting edge.