Cutting Insert Corner Radius Layout for Stable Hole-Forming

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Solution Overview

Problem

Conventional cutting inserts for end mills experience high machining loads and excessive fracture at the corner parts during hole-forming machining, particularly when removing residual cores, leading to instability and reduced tool life.

Innovation Solution

The cutting insert design features a larger radius of curvature for the third corner part on the tool center side and adjustable chip breakers, enhancing machining resistance and chip control, allowing for improved stability and extended tool life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the cutting insert is designed with a small radius of curvature for the corner part to improve chip breaking, then chip control is enhanced, but the machining resistance increases and fracture occurs

Engineering Contradiction:
Improvechip breaking performanceVSAvoidmachining resistance
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent applies different radius of curvature values to different corner parts of the cutting insert. Specifically, the third corner part (tool center side) has a larger radius of curvature (R3) to improve machining resistance and prevent fracture, while the first corner part (tool periphery side) has a smaller radius of curvature (R1) to maintain chip breaking performance. This local differentiation resolves the contradiction by optimizing each corner for its specific functional requirements.

Inventive Principle:
Principle #3Local quality

2Productivity

If the cutting insert is designed for multifunctional machining with double-sided center edge, then economic efficiency is improved, but the corner part experiences excessive load during hole-forming machining

Engineering Contradiction:
Improveeconomic efficiencyVSAvoidmachining load
Core Design Contradiction:
ProductivityVSForce

Solution Approach 1:

The patent optimizes the corner part geometry specifically for the multifunctional machining application. By providing the third corner part with a larger radius of curvature (R3), the design enhances the load-bearing capacity of the corner part that experiences excessive force during hole-forming machining, while maintaining the economic efficiency benefits of the double-sided center edge configuration.

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If the cutting insert corner part is designed to tolerate axial misalignment, then positioning flexibility is improved, but the load during core removal becomes excessively high

Engineering Contradiction:
Improveaxial misalignment toleranceVSAvoidcore removal load
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The patent addresses the contradiction by locally modifying the third corner part geometry with a larger radius of curvature (R3). This local optimization maintains the overall adaptability for axial misalignment while specifically enhancing the load-bearing capacity of the corner part during core removal operations, preventing excessive force concentration.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4578579A1Cutting insert and cutting tool comprising the same
Publication Date: 2025.07.02 TUNGALOY CORP
  • EP4578579A1 patent drawingFigure 1
  • EP4578579A1 patent drawingFigure 2
  • EP4578579A1 patent drawingFigure 3

AI summary

A cutting insert comprises a first end surface and a second end surface that are each formed in a substantially polygonal plate shape and each include a first long side and a second long side, and a first short side and a second short side that are located between the first long side and the second long side, the first end surface and the second end surface facing each other. The first end surface and the second end surface each have: a first cutting edge extending from the first long side to a first corner part that is located between the first long side and the first short side; and a second cutting edge extending from the second long side to a second corner part located between the second long side and the first short side. A radius of curvature R3 of a third corner part located on an opposite side of the first corner part with the first long side interposed therebetween is larger than a radius of curvature R1 of the first corner part.