Shoulder Milling Insert Waist Structure to Contain Edge Cracks

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Solution Overview

Problem

Cutting inserts for shoulder milling tools are prone to cracking and fracture due to excessive wear and large cutting forces, leading to potential failure during operations like shoulder, ramping, and plunge milling.

Innovation Solution

A trigonally shaped cutting insert with a median plane, featuring a countersunk circumferential waist portion that houses the main cutting edges, providing additional material support and preventing crack propagation, along with secondary cutting edges arranged to maintain integrity even if the main edges crack, resulting in improved resistance against fractures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the cutting insert uses a conventional design without a countersunk circumferential waist portion, then the structure is simpler, but the resistance against crack formation and fracture is insufficient

Engineering Contradiction:

Improveresistance against crack formation and fractureVSAvoidstructural complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The cutting insert is divided into a body portion and a countersunk circumferential waist portion, creating a distinct structural segmentation. The countersunk portion acts as a separate functional element that provides crack propagation resistance while maintaining overall structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The countersunk circumferential waist portion is designed in advance to provide material support and cushioning against crack propagation. This pre-positioned structural feature ensures that if cracks form in the cutting edges, they will be contained within the countersunk portion and prevented from propagating into the main body.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the main cutting edge is arranged outside the countersunk circumferential waist portion, then the cutting edge is more accessible, but cracks can propagate to the other side of the cutting insert causing complete failure

Engineering Contradiction:

Improveintegrity of cutting insertVSAvoidaccessibility of cutting edge

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The countersunk circumferential waist portion is pre-configured to contain and cushion against crack propagation. By positioning the main cutting edge within this countersunk portion, the design ensures that any cracks forming during operation will be contained within the countersunk region and cannot propagate to the other side of the insert.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The main cutting edge is nested within the countersunk circumferential waist portion, creating a protective enclosure. This nesting arrangement ensures the cutting edge remains accessible for cutting operations while being protected by the surrounding countersunk structure that prevents crack propagation.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Strength

If the cutting insert lacks a countersunk circumferential waist portion, then manufacturing is simpler, but the support amount of material outside the cutting edge is insufficient

Engineering Contradiction:

Improvesupport amount of materialVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The cutting insert structure is segmented into a body portion and a countersunk circumferential waist portion. This segmentation creates a distinct region of increased material support outside the cutting edge, providing enhanced structural strength without requiring complete redesign of the entire insert.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The countersunk circumferential waist portion creates a localized region of enhanced material support and structural strength. Rather than increasing the overall size of the insert, the design concentrates additional material support in the specific region where it is most needed - outside the main cutting edge - while maintaining a compact overall form.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP3338928B1Cutting insert and shoulder milling tool

Publication Date: 2022.03.30 SANDVIK INTELLECTUAL PROPERTY AB

Figure 1a~1b
Figure 1b'~1b''
Figure 1c~1c''

AI summary

Herein a cutting insert (2) for a shoulder milling tool is disclosed. The cutting insert (2) has a trigonal shape and comprises a first surface (14), a second surface (16), and a circumferential surface (18) extending between the first surface (14) and the second surface. The circumferential surface (18) comprises a countersunk circumferential waist portion (92). The circumferential surface (18) comprises a first and a second clearance surface extending along a first and a second main cutting edge (24, 24'). Each of the first and second clearance surfaces is forming a negative nominal clearance angle. Each of the first and second main cutting edges (24, 24') is arranged inside the countersunk circumferential waist portion (92), as seen in the view towards the first and second surfaces (14, 16), respectively.