Cutting Insert with Unequal Width Negative Land for Chatter Reduction
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Solution Overview
Problem
Conventional cutting inserts with hard sintered bodies face challenges in machining highly hard difficult-to-cut materials, such as heat-resistant alloys and hardened steels, due to frequent chipping and fracture, requiring multiple cutting inserts with different geometries for varying machining conditions, which increases costs and complexity.
Innovation Solution
A cutting insert with a cBN-based sintered body, ceramics, or cermet material featuring a flank face, nose R portion with a positive rake angle, and a negative land of unequal width, designed to reduce chatter and improve surface texture, manufactured using a method that allows for precise grinding of the rake face and negative land without releasing the blank material, ensuring stable cutting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard sintered body is used for cutting highly hard difficult-to-cut materials, then wear resistance is improved, but chipping and fracture of the cutting edge occur due to vibration and impact
Solution Approach 1:
The invention applies different geometric features to different locations on the cutting insert. A negative land (chamfer) is provided at the cutting edge ridge line to reinforce the edge against chipping and fracture, while the main cutting surface maintains its hard sintered body composition for wear resistance. This local differentiation allows the cutting edge to withstand impact and vibration without sacrificing the overall wear resistance of the hard sintered body material.
2Adaptability or versatility
If multiple cutting inserts with different geometries are used for varying machining conditions, then adaptability is improved, but device complexity and cost increase
Solution Approach 1:
The invention designs a universal cutting insert geometry that can handle multiple machining conditions. By incorporating a negative land at the cutting edge ridge line, the same insert geometry can be used for both roughing (where impact and vibration occur) and finishing (where surface quality is critical) operations. This eliminates the need to maintain multiple specialized insert inventories, reducing complexity while maintaining adaptability across different machining scenarios.
3Manufacturing precision
If the entire rake face is ground in parallel with the insert bottom surface, then manufacturing precision is improved, but manufacturing time increases
Solution Approach 1:
The negative land (chamfer) is formed at the cutting edge ridge line before the final rake face grinding operation. This preliminary action prepares the cutting edge geometry in advance, allowing the subsequent grinding process to focus only on achieving the precise rake face flatness without having to create the cutting edge reinforcement feature during the same operation. This sequencing improves manufacturing precision while reducing the overall manufacturing cycle time by dividing operations efficiently.
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 achieves stable life and reduced chatter during high-speed cutting of hard materials, producing a machined surface with excellent texture and allowing for high-volume mass production with improved quality.
Implementation Method 1
a cutting tool material composed of one of cBN based sintered body (sintered body composed mainly of cubic boron nitride), ceramics, and cermet
Implementation Method 2
a method is adopted to improve a cutting edge geometry to be transferred to a workpiece by performing grinding after a flank face and a rake face are sintered
Data Source
AI summary
A cutting insert including a surface involved in cutting, for which a cutting tool material of a hard sintered body is used. A radius of a nose R portion is 0.4 mm or greater and 2.4 mm or less, an apex angle α of the nose R portion is 50° or greater and 95° or less, a rake angle β at a position of a bisecting plane of the apex angle of the nose R portion is 1° or greater and 10° or less, a chamfer provided in a cutting edge portion is a negative land with unequal width, and at least on one side of the negative land with respect to a boundary which is an apex of a nose R portion cutting edge, a width of the negative land gradually decreases from the apex of the nose R portion cutting edge to a position at which the nose R portion cutting edge is connected to a linear cutting edge. Let W1 be the width of the negative land at the apex of the nose R portion cutting edge, and W2 be the width of the negative land at both ends of the nose R portion cutting edge, then the W1 is 0.04 mm or greater and 0.2 mm or less, and a ratio of the W1 to the W2 is 1.5 or greater.