Variable-Chamfer Cutting Insert for Push-Pull Machining Accuracy
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Solution Overview
Problem
Existing cutting inserts designed for push cutting are inadequate for pull cutting, leading to increased cutting resistance, chipping, and fracture, which shortens tool life and compromises machining accuracy for high hardness materials like hardened steel and heat-resistant alloys.
Innovation Solution
A cutting insert with a surface comprising cBN sintered material, ceramics, or cermet, featuring a rake face, flank face, and a chamfer with a minimum width along the connecting cutting edge portion, and wider chamfers for push and pull cutting edges to reduce thrust and feed force components, enhancing fracture resistance and preventing chattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the chamfer width is increased along the cutting edge for push cutting, then the fracture resistance is improved, but the cutting resistance increases and machining accuracy deteriorates
Solution Approach 1:
The chamfer width is varied locally along the cutting edge: wider chamfer at the push cutting portion for fracture resistance, and narrower chamfer at the pull cutting portion for reduced cutting resistance. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The cutting edge is segmented into distinct portions (push cutting portion and pull cutting portion) with different chamfer widths. This segmentation allows each portion to have optimized geometry for its specific cutting mode, preventing the trade-off between strength and precision.
2Force
If the chamfer width is decreased along the cutting edge for pull cutting, then the cutting resistance is reduced, but the fracture resistance deteriorates
Solution Approach 1:
The chamfer width is optimized locally for pull cutting operations: narrower chamfer at the pull cutting portion reduces cutting resistance and thrust force, while the wider chamfer at the push cutting portion maintains overall fracture resistance of the cutting edge.
Solution Approach 2:
The cutting edge is divided into functional segments where the pull cutting portion has reduced chamfer width for lower cutting forces, while the push cutting portion maintains wider chamfer for structural strength, resolving the force-strength contradiction.
3Ease of manufacture
If a uniform chamfer width is used along the entire cutting edge, then the manufacturing is simplified, but the tool life is shortened due to chipping and fracture in both push and pull cutting
Solution Approach 1:
Rather than using uniform chamfer width for ease of manufacture, the invention applies local quality variation: wider chamfer where strength is needed and narrower chamfer where cutting performance is critical, thereby extending tool life through optimized local geometry.
Solution Approach 2:
The chamfer width parameter is changed along the length of the cutting edge to optimize performance. This parameter variation prevents chipping and fracture by adapting the chamfer geometry to the specific mechanical demands of different cutting portions, extending tool life despite increased manufacturing complexity.
4Strength
If the chamfer width is increased to prevent chattering, then the fracture resistance is improved, but the thrust force component increases and machining accuracy deteriorates
Solution Approach 1:
The chamfer width is locally optimized: wider chamfer at the push cutting portion provides fracture resistance and reduces chattering, while narrower chamfer at the pull cutting portion minimizes thrust force, resolving the strength-force contradiction.
Solution Approach 2:
The cutting edge is segmented into push and pull cutting portions with differentiated chamfer widths. This segmentation allows the push cutting portion to handle chattering through wider chamfer while the pull cutting portion maintains low thrust force through narrower chamfer.
Data Source
AI summary
A cutting insert has a surface that relates to cutting, the surface comprising cBN sintered material, ceramics, or cermet. The cutting insert comprises: a rake face; a flank face; a chamfer located between the rake face and the flank face; and a cutting edge formed by a ridgeline at which the flank face and the chamfer intersect. The cutting edge comprises a cutting edge portion for push cutting, a cutting edge portion for pull cutting, and a connecting cutting edge portion located between the cutting edge portion for push cutting and the cutting edge portion for pull cutting. In the chamfer located along the cutting edge, the chamfer located along the connecting cutting edge portion has a minimum width.