Variable Radial Rake Cutting Insert for Titanium Milling
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Solution Overview
Problem
Cutting inserts used in peripheral rotary milling applications have a limited service life, especially when machining difficult-to-machine materials like titanium and nickel alloys, due to increased cutting edge load and lack of recognition of the quantitative relationship between insert geometry and tool holder position.
Innovation Solution
A parallelogram-shaped cutting insert with a variable radial rake angle, transitioning from positive to negative along the main cutting edge, and an optimized tool holder positioning system that balances cutting efficiency and edge strength, using equations to ensure optimal placement of the inserts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a positive radial rake angle is maintained along the main cutting edge, then cutting forces and power consumption are reduced, but cutting edge strength decreases
Solution Approach 1:
The patent applies different radial rake angles to different segments of the main cutting edge. The first portion has a first radial rake angle while the second portion has a second radial rake angle that differs from the first. This local differentiation allows the cutting edge to have positive rake angles in regions where cutting efficiency is needed while having different angle configurations in regions where edge strength is critical, thereby resolving the contradiction between reducing power consumption and maintaining cutting edge strength.
2Productivity
If parallelogram-shaped cutting inserts are used to increase depth of cut, then machining efficiency is improved, but cutting edge strength is reduced compared to square-shaped inserts
Solution Approach 1:
The patent modifies the parallelogram-shaped insert by creating a recess in one of the main cutting sides, forming a shoulder portion. This local structural modification strengthens the cutting edge in critical areas without changing the overall parallelogram shape, thereby maintaining the depth of cut capability and machining efficiency while compensating for the inherent weakness of parallelogram-shaped inserts.
3Ease of operation
If a larger radial clearance angle is used, then chip flow is improved, but cutting insert strength and stability in the tool holder decrease
Solution Approach 1:
The patent creates a recess in the main cutting side of the parallelogram-shaped insert, forming a shoulder portion that extends along the main cutting edge. This local structural feature provides better support and localization of the cutting insert in the tool holder, improving stability and reliability without requiring a reduction in radial clearance angle that would harm chip flow.
Data Source
Figure 1
Figure 2A~2B
Figure 3a~3d
AI summary
A generally parallelogram-shaped cutting insert includes a top face; first and second main radial clearance faces, each intersecting the top face; first and second minor axial clearance faces each intersecting the top face and connecting the first and second main radial clearance faces; and a main cutting edge at the intersection of the top face and the first main radial clearance face. According to one non-limiting embodiment, the main cutting edge comprises a variable radial rake angle including a portion having a positive radial rake angle and a portion having a negative radial rake angle.