Cutting Insert Breaker Groove Design for Low Cutting Force
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Solution Overview
Problem
Existing cutting inserts for turning and grooving face issues with excessive cutting force when processing thin and hard materials like stainless steel at low feed rates, due to chips being excessively restrained by the chip breaker, leading to increased deformation and complex chip shapes.
Innovation Solution
A cutting insert with a leading cutting edge having a rake angle of 20° to 35° and a rake face featuring a breaker groove with decreasing side face separation and four shoulder portions, optimized to reduce cutting force while maintaining high chip-processing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the breaker operates over a region extending to a position distant from the leading cutting edge, then chips are effectively curled and broken, but the chips are excessively restrained and the cutting force increases
Solution Approach 1:
The breaker groove is divided into multiple sections with different functions: a first section with a relatively large width that decreases with distance from the leading cutting edge to provide curling force, and a second section with a smaller width than the first section to provide bending force. This segmentation allows the breaker to process chips effectively while reducing excessive restraint and cutting force.
2Reliability
If the recess width gradually decreases with increasing distance from the cutting edge, then chips receive both curling force and bending force, but chips evacuate along the groove surface with increased bending, causing excessive restraint
Solution Approach 1:
Different sections of the breaker groove are designed with different width characteristics to provide locally appropriate functions. The first section has a width that decreases with distance to provide curling, while the second section has a smaller, more constrained width to provide bending. This local quality differentiation optimizes chip processing while avoiding excessive restraint.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cutting insert effectively reduces cutting force while maintaining high chip-processing performance by guiding and curling chips into a concave shape, reducing friction and preventing excessive chip restraint, resulting in smaller chip pieces and improved evacuation performance.
Implementation Method 1
the breaker groove includes opposing side faces separated from each other by a distance that decreases with increasing distance from the leading cutting edge
Implementation Method 2
chips are deformed by being pushed into the recess in the central region of the rake face in the width direction and bent in the width direction
Implementation Method 3
four shoulder portions of the same height that are formed on the opposing side faces at positions above the land portions
Implementation Method 4
the chips receive not only a curling force but also a bending force in the width direction
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A cutting insert includes a leading cutting edge having a rake angle in the range of 20° to 35° in a central region in a width direction; and a rake face having a breaker groove formed in the central region in the width direction and land portions formed in both end regions in the width direction. The land portions have a rake angle smaller than the rake angle in the central region in the width direction. The breaker groove includes opposing side faces separated from each other by a distance that decreases with increasing distance from the leading cutting edge and four shoulder portions of the same height that are formed on the opposing side faces at positions above the land portions, two of the shoulder portions being closer to the leading cutting edge and to outer sides in the width direction than the other two shoulder portions are.