Double-Sided Cutting Insert With Through Bore For Turbine Blade Machining

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Solution Overview

Problem

Existing double-sided milling cutting inserts with round cutting edges are limited to two usable cutting edges and lack a central through bore for clamping, requiring complex and expensive retaining systems, which restricts their usability and efficiency in machining turbine blades.

Innovation Solution

A double-sided indexable cutting insert with four or more round cutting edges, each extending over 120°, featuring a through bore for secure retention with a clamping screw, allowing for improved cutting tool functionality and reduced complexity in retaining systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a double-sided cutting insert is designed with round cutting edges, then the cutting edge can machine internal surfaces of turbine blades, but the total usable sector is limited to greater than 120°, allowing only two indexings

Engineering Contradiction:
Improveusable sectorVSAvoidnumber of indexings
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The cutting insert is divided into two separate working faces, each containing cutting edges. This segmentation allows the insert to be indexed multiple times (at least four indexings) by rotating the insert to use different faces and cutting edges, thereby increasing productivity while maintaining adaptability for machining internal surfaces.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a through bore is added to the cutting insert for clamping screw passage, then the retaining system becomes simpler and less expensive, but the insert structure becomes more complex

Engineering Contradiction:
Improveretaining system complexityVSAvoidinsert structure
Core Design Contradiction:
Device complexityVSShape

Solution Approach 1:

Instead of using a complex retaining system that avoids the through bore, the invention inverts the approach by incorporating the through bore directly into the insert structure. This allows the use of a simple clamping screw for retention, reducing the overall complexity of the retaining system while accepting the modified insert shape.

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentEP2323794B1Cutting tool and round double sided cutting insert therefor
Publication Date: 2017.04.19 ISCAR LTD
  • EP2323794B1 patent drawingFigure 1~2
  • EP2323794B1 patent drawingFigure 3~4
  • EP2323794B1 patent drawingFigure 5~6

AI summary

A cutting insert for retention in a rotating cutting tool having an axis of rotation. The cutting insert comprising two opposing end surfaces and a peripheral side surface extending therebetween, each end surface having a mutual first axis of symmetry passing through the end surfaces about which each end surface has N-fold rotational symmetry for some value of N where N is chosen from the group of 2, 3 and 4. A peripheral cutting edge formed at the junction between each end surface and the peripheral side surface, the peripheral edge comprising N curved cutting edges merging with N straight cutting edges which extend between the curved cutting edges at extremities thereof. The curved cutting edges of the two end surfaces do not overlap in an end view of the cutting insert along the first axis of symmetry.