Cutting Insert Rake Surface for Chip Curling

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Solution Overview

Problem

Conventional cutting tools face challenges in chip discharge during finish cuts, leading to potential damage of the machined surface due to uncurled and undivided chips, particularly when the depth of cut is small.

Innovation Solution

A cutting insert with a unique rake surface configuration, featuring a first rake surface and a second rake surface inclined at different angles, along with a protruded portion, which facilitates stable curling of chips even under conditions where the corner and minor cutting edges are primarily used, enhancing chip discharge performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional cutting plate configuration is used, then the structure is simple, but chips cannot be properly curled and divided under small depth of cut conditions, causing damage to the machined surface

Engineering Contradiction:

Improvechip discharge performanceVSAvoidrake surface configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The rake surface is segmented into multiple distinct regions (first rake surface, second rake surface, third rake surface) with different inclination angles, allowing each segment to perform a specific function in chip control and curling

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the rake surface are given different local properties through varying inclination angles - the first rake surface has a larger inclination angle for initial chip engagement, while the second and third rake surfaces have smaller angles for chip curling and discharge

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If the depth of cut is small (finish cut conditions), then the machining precision is improved, but chip curling becomes unstable and chips may damage the machined surface

Engineering Contradiction:

Improvemachined surface qualityVSAvoidchip discharge performance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The inclination angles of the rake surface segments are specifically optimized for small depth of cut conditions, with the first rake surface having a larger inclination angle to engage chips effectively and the second and third rake surfaces having smaller angles to promote stable curling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protruded part on the second rake surface introduces a curved geometric feature that helps initiate and stabilize chip curling, transforming the chip flow from linear to curved trajectory for better control

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentEP2774706B1Cutting insert, cutting tool, and method for manufacturing cut product using cutting tool

Publication Date: 2020.11.04 KYOCERA CORP

Figure 1(a)~1(d)
Figure 2(a)~2(b)
Figure 3

AI summary

In a cutting insert according to an embodiment of the present invention, an upper surface sequentially includes a first rake surface and a second rake surface. The first rake surface being inclined toward the lower surface as going inward from the cutting edge at a first rake angle on a basis of a perpendicular plane perpendicular to a central axis extending between the upper surface and a lower surface. The second rake surface is located more inward than the first rake surface and is inclined toward the lower surface at a second rake angle different from the first rake angle on the basis of the perpendicular plane. An intersecting part of the first rake surface and the second rake surface includes a protruded part located at a highest position in a region of the intersecting part along the second side surface. A cutting tool with the cutting insert, and a method of producing a machined product by using the cutting tool are also provided.