Double-Sided Cutting Insert With Positive Rake for Right-Angle Milling
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Solution Overview
Problem
Conventional cutting inserts for right angle machining are inefficient due to short life expectancy and difficulty in performing effective cutting at high speeds, high feed rates, or high depths of cut, especially with negative rake angles that increase resistance.
Innovation Solution
A double-sided polygonal cutting insert with convex and concave curved main and secondary cutting edges, and specifically designed insert pockets forming a positive axial rake angle, allowing for stable cutting with increased perpendicularity and reduced machining errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cutting insert is positioned at a negative rake angle to ensure relief angle during machining, then the relief angle is ensured, but the cutting insert is subjected to more resistance and is unsuitable for high speed, high feed rate or high depth of cut machining
Solution Approach 1:
The patent inverts the conventional negative rake angle configuration to a positive rake angle (α ≥ 0°). This inversion fundamentally changes the cutting geometry, reducing cutting resistance while maintaining effective relief during machining operations, thereby enabling high speed, high feed rate, and high depth of cut machining
Solution Approach 2:
The patent changes the rake angle parameter from negative to positive (α ≥ 0°), and optimizes other geometric parameters including the main cutting edge angle (β1 = 45°-60°) and secondary cutting edge angle (β2 = 30°-45°). These parameter changes collectively reduce cutting resistance while ensuring proper relief angle during machining
2Device complexity
If a single-sided cutting insert is used with cutting edge only between upper surface and flank surface, then the structure is simple, but the life expectancy is short and efficiency is low due to few available cutting edges
Solution Approach 1:
The patent designs a double-sided cutting insert where both the upper surface and lower surface have cutting edges formed between respective flank surfaces. This multi-functional design allows the insert to be used on both sides, effectively doubling the number of available cutting edges and extending tool life without significantly increasing structural complexity
3Force
If the cutting edge is obliquely arranged nonparallel to the upper or lower surface to reduce negative rake angle, then the rake angle is reduced, but the cutting insert still has difficulties in performing effective cutting in high speed, high feed rate or high depth of cut machining
Solution Approach 1:
Instead of merely reducing the negative rake angle through oblique arrangement, the patent inverts the approach by adopting a positive rake angle (α ≥ 0°). This fundamental inversion, combined with optimized cutting edge angles, fully resolves the cutting effectiveness issue for high speed, high feed rate, and high depth of cut machining
Data Source
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AI summary
A polygonal cutting insert for right angle machining has opposed upper and lower surfaces, a peripheral side surface interconnecting the upper and lower surfaces and having curved first and fourth side surfaces and plane second and third side surfaces, and main and secondary cutting edges alternately formed along the outer peripheries of the upper and lower surfaces. The adjacent main and secondary cutting edges form a right angle therebetween. The first side surface adjoins the main cutting edge of the upper surface. The second side surface adjoins the secondary cutting edge of the lower surface. The third side surface adjoins the secondary cutting edge of the upper surface. The fourth side surface adjoins the main cutting edge of the lower surface. The cutting insert is mounted on a milling cutter at a positive axial rake angle.