Cutting Insert Oval Bore Indexing

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Solution Overview

Problem

Existing cutting tool fastening arrangements face issues with asymmetrical screw heads leading to inaccuracies and reduced torque capacity due to chamfering, resulting in unpredictable insert placement and potential sudden release, as well as asymmetric force distribution causing locating inaccuracies and shortened tool life.

Innovation Solution

A cutting insert assembly with a non-circular bore having a perpendicular oval cross-section and a fastening member with a contour that changes size to facilitate secure engagement and easy removal without complete screw removal, ensuring symmetrical force distribution and enhanced torque capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a standard cutting insert with asymmetric chamfered screw head is used, then the cutting insert can be removed without completely unscrewing the locking screw, but the screw head is weakened and torque capacity is reduced leading to inaccuracies and potential sudden release

Engineering Contradiction:

Improveease of insert removalVSAvoidscrew head strength and torque capacity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The bore is segmented into three distinct portions: a first bore portion, a second bore portion, and a third intermediate bore portion. This segmentation allows the fastening member head to be partially received in one portion while protruding through another, enabling insert removal without complete screw unscrewing while maintaining full screw strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces a dimensional variation in the bore cross-section along its length, with the third bore portion having different dimensions than the first and second portions. This dimensional change creates the geometric condition that allows the fastening member head to pass through the bore while remaining threaded, resolving the contradiction between ease of removal and screw strength.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If asymmetric chamfering is applied to the screw head to enable partial removal, then insert removal is facilitated, but the screw head is weakened and torque capacity is reduced

Engineering Contradiction:

Improveease of insert removalVSAvoidscrew head strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If asymmetric locking pin arrangement is used, then indexing is enabled, but asymmetric force distribution causes locating inaccuracies and shortened tool life

Engineering Contradiction:

Improveinsert indexing capabilityVSAvoidforce distribution symmetry and tool life

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention deliberately introduces asymmetry in the form of a keyway and key arrangement that is asymmetric with respect to the bore axis. This controlled asymmetry enables insert indexing while the overall symmetric bore structure maintains balanced force distribution, resolving the contradiction between indexing capability and force distribution symmetry.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The asymmetric keyway and key arrangement is applied locally at specific positions in the bore, while the overall bore structure remains symmetric. This localized asymmetry provides indexing functionality without compromising the global symmetry needed for balanced force distribution and accurate locating.

Inventive Principle:

Principle #3Local quality

4Measurement precision

If the fastening member head contour is large to ensure secure engagement, then locating accuracy is improved, but the head cannot pass through the bore for easy removal

Engineering Contradiction:

Improveinsert placement accuracyVSAvoidease of insert removal

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP2424699B1Cutting insert and cutting insert assembly

Publication Date: 2020.03.25 ISCAR LTD

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Figure 3~4

AI summary

A cutting insert assembly (22) having an insert pocket (30) having a pocket bore (54), a cutting insert (40,140,240,340) and a fastening member (50) coupling the cutting insert (40,140,240,340) in the insert pocket (30). The cutting insert (40,140,240,340) having a cutting insert bore (60,160,260,360), a first surface (62,162,362), a second surface (64,164,364) and a peripheral surface (66,166,366) extending therebetween. The first and second surfaces ( (62, 162, 362), (64, 164, 364) ) meeting the peripheral surface (66,166,366) at first and second peripheral edges (42,142,342,44,144,344), respectively, at least a portion of at least one of the first and second peripheral edges (42,142,342,44,144,344) forming a cutting edge (46,146,346). The cutting insert bore (60,160,260,360) having at least two portions, the smallest of which, has an oval cross section allowing a for quick replacing or indexing of the cutting insert (40,140,240,340), without having to completely remove the fastening member (50) from the pocket bore (54).