Bent-Line Indexable Rotary Insert for Wear-Resistant Cutting
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Solution Overview
Problem
Existing indexable rotary cutting tools with cemented carbide inserts face premature wear and chipping when cutting difficult-to-cut materials like stainless steel and heat-resistant alloys due to insufficient cutting edge strength and increased cutting resistance, leading to reduced insert life and high machining costs.
Innovation Solution
The insert features a bent-line-shaped main cutting edge composed of first to third straight cutting edges with specific cutting edge angles and ridgeline configurations, where the second straight cutting edge is positioned outermost, and the cutting edge angles meet the relation β1 > β2 > β3, along with inclined and notched surfaces to enhance strength and reduce cutting resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the entire long-side cutting edge has a cutting edge comprising the circular cutting edge and the straight cutting edge, then the clearance angle is sufficient, but sufficient strength cannot be secured particularly in the straight cutting edge
Solution Approach 1:
The main cutting edge is segmented into multiple straight cutting edge portions (first, second, third straight cutting edge portions) connected in a bent-line shape. This segmentation allows each portion to have optimized geometry for strength while avoiding the need for complex circular cutting edges that are difficult and expensive to manufacture with high precision.
Solution Approach 2:
Instead of using a circular cutting edge with varying clearance angles as in prior art, the invention inverts the approach by using straight cutting edge portions connected at obtuse angles. This inversion simplifies manufacturing while maintaining sufficient clearance angle through the bent-line configuration rather than through curved geometry.
2Productivity
If the main cutting edge has a gradually increasing clearance angle by the twisted surface portion, then the cutting performance is improved, but the cutting edge does not have sufficient strength near the corner cutting edge
Solution Approach 1:
Different straight cutting edge portions have different local geometries and clearance angles optimized for their specific functions. The first straight cutting edge portion has geometry optimized for corner cutting edge strength, while subsequent portions have geometry optimized for cutting performance. This local quality differentiation allows simultaneous optimization of both strength and productivity.
Solution Approach 2:
The cutting edge is formed as a composite structure with multiple straight cutting edge portions made of cemented carbide material, where each portion contributes different properties. The bent-line configuration with obtuse angles creates a composite geometric structure that provides both strength at critical locations and optimized cutting performance at other locations.
3Force
If the cutting edge is made with straight cutting edge portions connected at obtuse angles, then the cutting resistance is reduced and chip discharge is stabilized, but the cutting edge strength may be compromised without proper configuration
Solution Approach 1:
The straight cutting edge portions are connected at obtuse angles to form a bent-line shape that approximates a curved path. This bent-line configuration reduces cutting resistance and stabilizes chip discharge by creating a more gradual cutting action, while the obtuse angle connections maintain structural strength by avoiding sharp acute angles that would be stress concentration points.
Data Source
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AI summary
A substantially parallelogramatic insert having a downward inclined main cutting edge and an auxiliary cutting edge in part of a long-side ridgeline and a short-side ridgeline adjacent to a pair of corner cutting edges of an upper surface; the main cutting edge being constituted by first to third straight cutting edges; the first to third straight cutting edges being connected in a bent-line shape with inward obtuse crossing angles when viewed from above, such that the second straight cutting edge is positioned outermost; and cutting edge angles β1, β2, β3 between the rake faces and flanks of the first to third straight cutting edges meeting the relation of β1 > β2 > β3.