Indexable Drill Insert Geometry for Stable Chip Flow and Low Burrs
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Solution Overview
Problem
Conventional indexable insert drills with inner and outer peripheral cutting edges face issues with chip division and burr formation, leading to potential damage to drilled holes and chip discharge flutes due to uneven cutting speeds and chip behavior.
Innovation Solution
The design of an indexable insert with a polygonal upper surface, inclined cutting edges, and a through hole for secure attachment, featuring a combination of straight and concave curvilinear cutting edges with varying radii of curvature to stabilize chip formation and reduce burr formation, along with a method for manufacturing machined products using such a drill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cutting with the inner peripheral cutting edge is performed at low cutting speed, then chip spirally extending long occurs, but fine burr formation and damage to inner peripheral surface occur
Solution Approach 1:
The insert is designed with different cutting edge configurations for inner and outer peripheral cutting edges. The outer peripheral cutting edge has a specific shape optimized for high-speed cutting to prevent chip division, while the inner peripheral cutting edge is optimized for low-speed cutting to prevent burr formation and chip damage, allowing each region to have locally optimized quality for its specific cutting conditions
Solution Approach 2:
Instead of using the same insert design for both inner and outer cutting edges, the invention inverts the approach by designing specialized inserts for each position with opposite optimization priorities - outer insert optimized for speed and chip control, inner insert optimized for burr prevention and chip integrity
2Productivity
If cutting with the outer peripheral cutting edge is performed at high cutting speed, then cutting efficiency is improved, but chip division occurs leading to burr formation
Solution Approach 1:
The outer peripheral cutting edge insert is designed with specific geometric characteristics optimized for high-speed cutting operations. The insert shape and cutting edge configuration are locally optimized to maintain chip integrity at high speeds, preventing chip division and subsequent burr formation while preserving cutting efficiency
3Ease of operation
If conventional inserts are used with uneven cutting speeds, then drilling operation can be performed, but damage to inner peripheral surface and chip discharge flute occurs
Solution Approach 1:
The invention applies locally optimized insert designs for different positions in the drill - inner peripheral inserts and outer peripheral inserts with different geometric characteristics. This local differentiation ensures that each cutting edge performs optimally under its specific conditions, preventing chip issues that could damage the drilled hole surface and chip discharge flute, thereby improving reliability
Solution Approach 2:
The drill system is segmented into multiple insert positions (inner and outer peripheral) with specialized inserts for each position. This segmentation allows independent optimization of each cutting edge for its specific function, preventing harmful chip behavior that could damage critical surfaces while maintaining ease of operation
Data Source
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AI summary
An insert according to an embodiment includes an upper surface including a corner part, a lower surface, a side surface, and a cutting edge. The cutting edge includes a first cutting edge located at the corner part, a second cutting edge adjacent to the first cutting edge, a third cutting edge adjacent to the second cutting edge, and a fourth cutting edge adjacent to the third cutting edge. Each of the third cutting edge and the fourth cutting edge has a concave curvilinear shape extending downward in a side view. A radius of curvature of the fourth cutting edge is smaller than a radius of curvature of the third cutting edge.