Rotary Cutting Insert Geometry for Chipping-Resistant Finishing
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Solution Overview
Problem
Indexable rotary cutting tools with small inserts face issues of chipping and breakage due to insufficient rigidity, leading to reduced tool life and deteriorated surface quality, particularly in corner and peripheral cutting edges.
Innovation Solution
The design features inserts with corner and peripheral cutting edges having different clearance angles, a receding portion on the peripheral cutting edge, and an angle-changing surface portion on the flank connecting these edges, providing improved breakage and wear resistance by distributing stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small inserts are used for accurate finishing, then manufacturing precision is improved, but reliability deteriorates due to chipping and breakage
Solution Approach 1:
The insert applies local quality by providing different clearance angles at different locations: a first clearance angle for the bottom cutting edge and a second clearance angle for the peripheral cutting edge. This allows each region to be optimized for its specific function - the bottom edge for stability and the peripheral edge for cutting performance - thereby preventing chipping while maintaining finishing quality.
Solution Approach 2:
The insert incorporates dynamic elements through the angle-changing surface portion that provides a clearance angle transitioning from the first clearance angle to the second clearance angle. This gradual transition allows the cutting edge to adapt to varying stress conditions during cutting, improving both reliability and surface quality.
2Reliability
If vibration of cutting edges is reduced, then reliability is improved, but manufacturing precision deteriorates due to insufficient cutting performance
Solution Approach 1:
The insert provides different clearance angles at different locations to balance vibration reduction and cutting performance. The bottom cutting edge has a larger clearance angle for stability and vibration reduction, while the peripheral cutting edge has a smaller clearance angle for effective cutting, thus resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
The angle-changing surface portion creates a dynamic transition zone that allows the clearance angle to vary along the cutting edge. This dynamic design enables the insert to maintain stability where needed while preserving cutting performance where required, effectively resolving the contradiction.
3Device complexity
If the same clearance angle is provided for all cutting edges, then device complexity is reduced, but manufacturing precision deteriorates due to inability to optimize different cutting edges
Solution Approach 1:
The insert implements local quality by providing different clearance angles for different cutting edges. The bottom cutting edge receives a first clearance angle optimized for stability, while the peripheral cutting edge receives a second clearance angle optimized for cutting performance. This localized optimization improves manufacturing precision without excessive complexity.
Solution Approach 2:
The angle-changing surface portion introduces a dynamic element that allows the clearance angle to transition smoothly between the first and second clearance angles. This dynamic transition zone enables the insert to achieve optimized performance for different cutting edges while maintaining a relatively simple overall structure.
Data Source
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Figure 3
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AI summary
An insert detachably attached to an indexable rotary cutting tool, comprising an upper surface having cutting edges along the ridgeline, a lower surface, side surfaces, and a center hole for a fastening screw; each cutting edge comprising a corner cutting edge formed in each acute corner portion, and a bottom cutting edge and a peripheral cutting edge formed along the ridgelines on both sides of the corner cutting edge; the bottom cutting edge and the peripheral cutting edge having different clearance angles; a flank of the corner cutting edge comprising an angle-changing surface portion having a clearance angle continuously changing in a region from the bottom cutting edge to the peripheral cutting edge; and the length of the peripheral cutting edge being restricted by a receding portion adjacent to an upper end of the peripheral cutting edge.