Rotary Cutter Insert Layout for Lower Ramp-Cutting Edge Fracture

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Solution Overview

Problem

Roughing cutters with triangular cutting inserts face issues with fracture of cutting edge portions that serve as both major and inner cutting edges, particularly during ramp cutting, due to excessive load on these edges.

Innovation Solution

The indexable rotary cutting tool features cutting inserts with wave-shaped major cutting edges, where adjacent inserts' rotational trajectories coincide and overlap, distributing the load and reducing stress on the cutting edges, with outwardly-curved portions serving as both major and inner cutting edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If cutting inserts are arranged with coinciding rotational trajectories to distribute load, then durability is improved, but manufacturing precision may worsen due to overlapping cutting edges

Engineering Contradiction:
Improvetool durabilityVSAvoidcutting precision
Core Design Contradiction:
Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

The major cutting edge is segmented into multiple sections along its length, with different sections serving different functions. The first section performs primary cutting, the second section performs both cutting and acts as an inner cutting edge for ramp cutting, and the third section acts as an inner cutting edge. This segmentation allows the tool to maintain both durability through load distribution and precision through functional differentiation of edge sections.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the cutting insert are given different local qualities and functions. The first section is optimized for primary cutting operations, while the second and third sections are optimized for ramp cutting operations. This local quality differentiation ensures that each portion of the cutting edge performs its specific function optimally, maintaining both tool durability and manufacturing precision.

Inventive Principle:
Principle #3Local quality

2Object-generated harmful factors

If wave-shaped cutting edges are used to reduce chip size, then chip disposal capacity is improved, but cutting edge strength deteriorates due to increased curvature

Engineering Contradiction:
Improvechip disposal capacityVSAvoidcutting edge strength
Core Design Contradiction:
Object-generated harmful factorsVSStrength

Solution Approach 1:

The wave-shaped major cutting edge is divided into multiple sections, with the second section having a smaller wave amplitude than the first section. This segmentation of the wave shape allows the first section to effectively break chips into small pieces for improved disposal, while the second section maintains greater strength for ramp cutting operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the wave-shaped cutting edge have different local characteristics. The first section has larger wave amplitude optimized for chip breaking, while the second section has smaller wave amplitude optimized for maintaining strength during ramp cutting. This local quality variation resolves the contradiction between chip disposal capacity and cutting edge strength.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3147057B1Indexable rotary cutting tool
Publication Date: 2022.03.02 TUNGALOY CORP
  • EP3147057B1 patent drawingFigure 1
  • EP3147057B1 patent drawingFigure 2
  • EP3147057B1 patent drawingFigure 3

AI summary

A plurality of grooves (27) is formed and a plurality of insert seats (28) is formed in each of the grooves, and cutting inserts (30) are removably arranged onto the insert seats (28). The cutting insert (30) has a major cutting edge (34), a corner cutting edge, and a minor cutting edge (35). The major cutting edge (34) is formed in a wave shape as viewed from a direction of a rake surface. The cutting inserts (30) are arranged such that, in rotational trajectories formed by the major cutting edges (34) of the respective cutting inserts (30) when a roughing cutter (10) is rotated around a rotational axis (O), the phases of the waves of the rotational trajectories formed by the cutting inserts (30) that are adjacent to each other in a direction along the rotational axis O coincide with each other in one groove (27), and such that the rotational trajectories of at least part of cutting edge portions of at least some cutting inserts (30) are overlapped with each other in the direction of the rotational axis (O). Accordingly, even when the cutting edge portion is used as a major cutting edge and as an inner cutting edge, it is still possible to reduce cutting load and suppress breakage.