Cutting Insert Curved Edge Reduces Thrust Force

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Solution Overview

Problem

Conventional cutting inserts face issues with surface damage and cutting edge fractures due to high thrust forces and large cutting edge angles, which lead to reduced feed rates and inefficient machining processes.

Innovation Solution

A cutting insert design featuring a polygonal upper and lower surface with specific cutting edge configurations, including a major cutting edge with an upwardly protruding curvilinear shape and connecting edges, which reduces cutting resistance and minimizes the risk of edge fractures by distributing load and reducing thrust forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cutting edge angle is large, then the chip thickness is large and cutting resistance is high, but heat accumulates in the cutting edge causing fractures

Engineering Contradiction:

Improvefeed per revolutionVSAvoidcutting edge fracture resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The cutting edge is designed with a curved profile instead of a straight line, creating an upwardly protruding shape that reduces the effective cutting edge angle while maintaining chip thickness control. This curvature allows the cutting edge to gradually engage the workpiece, distributing the cutting force and reducing heat concentration that leads to fractures.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

Different segments of the cutting edge have different geometries: the front portion has a smaller effective angle for reduced thrust force and heat generation, while the rear portion maintains adequate angle for effective chip removal. This local variation in cutting edge geometry optimizes both productivity and reliability.

Inventive Principle:

Principle #3Local quality

2Productivity

If the cutting edge angle is decreased to increase feed per revolution, then productivity improves, but the thrust force increases causing the rear edge to contact the finished surface

Engineering Contradiction:

Improvefeed per revolutionVSAvoidfinished surface quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The upwardly protruding curved shape of the cutting edge creates a natural clearance between the rear portion of the cutting edge and the finished surface. As the tool advances, the curved profile ensures that the rear edge lifts away from the workpiece, preventing contact and surface damage while allowing higher feed rates.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The cutting edge geometry is extended into the vertical dimension with an upward protrusion, creating three-dimensional clearance space that prevents the rear edge from contacting the finished surface. This dimensional addition solves the interference problem without compromising feed rate.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If a flat cutting edge parallel to the workpiece surface is used, then surface finish is improved, but the thrust force causes rear edge contact with the finished surface

Engineering Contradiction:

Improvesurface finish qualityVSAvoidfeed per revolution

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The flat cutting edge is modified with an upwardly protruding curved shape that maintains parallelism with the workpiece surface for accurate finishing while creating vertical clearance. This curvature allows the rear edge to clear the finished surface, enabling higher feed rates without sacrificing surface quality.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Reliability

If the feed per revolution is decreased to prevent cutting edge fractures, then cutting edge reliability improves, but machining efficiency decreases

Engineering Contradiction:

Improvecutting edge durabilityVSAvoidmachining efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The curved cutting edge profile reduces thrust force and heat generation, allowing the cutting edge to withstand higher loads without fracturing. This enables maintenance of higher feed rates that improve machining efficiency while the curved geometry continues to protect against fracture by distributing stresses more favorably.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS10213849B2Cutting insert, cutting tool, and method of manufacturing a machined product

Publication Date: 2019.02.26 KYOCERA CORP

AI summary

A cutting insert according to an embodiment of the present invention has a cutting edge having a first corner cutting edge, a flat cutting edge, a connecting edge, a major cutting edge, and a second corner cutting edge in the order named. The major cutting edge has an upwardly protruding curvilinear portion, a first straight line portion extending from the curvilinear portion toward the connecting edge, and a second straight line portion extending from the curvilinear portion toward the second corner cutting edge. The flat cutting edge and the major cutting edge have a straight line shape, and the connecting edge has an outwardly protruding curvilinear shape in a top view. The flat cutting edge, the connecting edge, and the first straight line portion are located on a straight line in a side view.