Variable-Rake Cutting Insert for Chip Control Across Cutting Depths
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Solution Overview
Problem
Conventional cutting inserts struggle to effectively cover both low-depth-of-cut (fine finishing) and high-depth-of-cut machining operations with a single insert, often resulting in suboptimal chip control and increased burr formation.
Innovation Solution
A cutting insert design featuring a first projection with a height decreasing towards the central axis, a second projection with an increasing height, an inclined portion with varying rake angles, and a multi-step second projection to guide and discharge chips efficiently, allowing for both low-depth-of-cut and high-depth-of-cut machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional cutting insert structure is used, then it can perform high-depth-of-cut machining, but it cannot achieve good chip control in low-depth-of-cut finishing operations
Solution Approach 1:
The cutting insert applies local quality by providing different rake angles in different regions: a first rake angle in the low-depth-of-cut region and a second rake angle in the middle-depth-of-cut region. This allows each region to be optimized for its specific machining conditions, achieving both fine finishing quality and expanded application range with a single insert.
Solution Approach 2:
The cutting insert segments the cutting edge into multiple regions with distinct geometric features: a corner portion with specific breaker projection height, an intermediate portion with inclined surface, and a main portion with different rake angle. This segmentation enables each segment to perform its specific function for different machining depths.
2Manufacturing precision
If the breaker projection height is increased to ensure chip control during finishing, then low-depth-of-cut performance improves, but the insert cannot maintain effectiveness for high-depth-of-cut operations
Solution Approach 1:
The breaker projection height is optimized locally for finishing operations while the rake angle is varied across different regions. The corner portion has a breaker projection height of 0.05-0.15mm for good chip control in finishing, while the rake angle changes from 5-15 degrees in the low-depth region to 15-25 degrees in the middle-depth region, maintaining effectiveness across different machining depths.
Solution Approach 2:
The cutting insert uses dynamic geometry where the rake angle is not fixed but varies continuously from the corner portion toward the center. This dynamic variation in rake angle (5-25 degrees) allows the insert to adapt to different machining conditions and depths within a single insert design.
3Adaptability or versatility
If a single cutting insert is designed to cover both low and middle depth-of-cut regions, then versatility improves, but chip control and burr prevention become problematic
Solution Approach 1:
Different rake angles are applied locally to different regions: 5-15 degrees for low-depth-of-cut to control chip flow and 15-25 degrees for middle-depth-of-cut to prevent burrs and chattering. This local optimization eliminates burr formation across the full application range.
Solution Approach 2:
The rake angle parameter is changed across different regions of the cutting insert. By varying the rake angle from 5-15 degrees near the corner to 15-25 degrees toward the center, the insert can handle different machining depths effectively while preventing harmful effects like burrs.
Data Source
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AI summary
It is intended to allow a wide range including a low region (fine finishing) to a middle region (medium cutting) to be covered with a single insert. A cutting insert (10) includes an upper surface, a lower surface, a peripheral side surface, a cutting edge (20) including a main cutting edge and a corner cutting edge, a corner portion, a projecting portion formed to extend from the corner portion toward a central axis and including a first projection (41) and a second projection (42), a rake portion (50), and an inclined portion (S) provided at the cutting edge. The inclined portion has a first inclined portion beginning at an intermediate point in the corner cutting edge, while the rake portion has a shape in which an angular degree of a rake angle gradually increases with distance from the corner portion.