Cutting Insert Flank Design for Chatter Suppression
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Solution Overview
Problem
In 90° shoulder milling, conventional cutting inserts face challenges with chatter due to low tool rigidity, which worsens with increased radial depth of cut and is exacerbated by miniaturization, leading to poor surface finish and reduced tool life.
Innovation Solution
A cutting insert with a unique configuration featuring a triangular upper surface, three cutting edges, and a main side-surface portion divided into four flank portions with specific slope angles and widths, designed to enhance process damping and interference with the workpiece, reducing chatter through optimized relief angles and frictional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the cutting insert size is reduced for miniaturization, then the adaptability to workpieces is improved, but the overall strength becomes insufficient and chatter is more likely to occur
Solution Approach 1:
The flank is divided into three distinct stages (twisted face portion, curved surface portion, flat surface portion) with different functions. This segmentation allows each portion to contribute specifically to chatter suppression while maintaining overall insert strength even at reduced sizes.
Solution Approach 2:
Different portions of the flank are given different geometric properties: the twisted face portion has a gradually varying relief angle for chip flow, the curved surface portion provides transition and local support, and the flat surface portion ensures stable contact with the tool body. This local differentiation optimizes performance at each location while maintaining overall structural integrity.
2Productivity
If the radial depth of cut is increased for increasing efficiency, then the productivity is improved, but chatter is more likely to occur due to increased regenerative effect
Solution Approach 1:
The invention converts the harmful regenerative chatter effect into a beneficial process damping effect. By designing the flank portions to contact the workpiece during cutting, the vibration is suppressed through friction and mechanical damping, transforming the harmful chatter into a stabilizing force that allows deeper cuts without vibration.
Solution Approach 2:
The curved surface portion and flat surface portion are specifically designed to interact with the workpiece in a controlled manner during cutting, creating mechanical damping that suppresses chatter vibrations. This controlled vibration interaction allows higher productivity while maintaining surface quality.
3Ease of operation
If the relief angle of the first flank portion is increased for reducing cutting resistance, then the ease of operation is improved, but the process damping effect is reduced and chatter increases
Solution Approach 1:
The relief angle of the first flank portion is optimized to a specific range (5° to 15°) that balances two competing requirements: providing sufficient clearance to reduce cutting resistance and friction, while maintaining enough contact between the flank and workpiece to generate process damping. This parameter optimization resolves the contradiction between ease of operation and chatter suppression.
Solution Approach 2:
Different flank portions have different relief angle characteristics: the first flank portion has a controlled relief angle for balanced cutting resistance and damping, the second flank portion has a larger relief angle for chip flow, and the third flank portion has minimal relief for stable tool body contact. This local differentiation allows each portion to optimize its function without compromising overall performance.
4Adaptability or versatility
If the tool overhang is increased for machining thin workpieces, then the adaptability to workpieces is improved, but the tool rigidity is reduced and chatter is more likely to occur
Solution Approach 1:
The process damping effect generated by the flank-workpiece contact converts the harmful effect of reduced tool rigidity (due to overhang) into a beneficial vibration suppression mechanism. The friction and mechanical contact between the flank portions and workpiece create damping that counteracts the reduced stiffness, enabling stable cutting even with long overhang tools on thin workpieces.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses chatter, improves cutting performance by maintaining balance in cutting resistance, and enhances tool rigidity, preventing tool lifting and chatter-related issues, thus ensuring better accuracy and extended tool life.
Implementation Method 1
a first flank portion 18...having a smaller slope angle...capable of interfering with the workpiece during cutting...by bringing about process damping through interference of the first flank portion 18 with the workpiece
Implementation Method 2
chatter is more likely to occur...suppression of chatter is an important issue in 90° shoulder milling
Data Source
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AI summary
The present invention provides a cutting insert (1) suitable for 90° shoulder milling. The cutting insert (1) includes two end surfaces: first and second end surfaces (2, 3); a peripheral side surface (4) extending therebetween; and a cutting edge (6) formed at an intersecting ridge portion between the first end surface and the peripheral side surface. The cutting edge (6) is formed so that the first end surface (2) functions as a rake face and a part of the peripheral side surface (4) functions as a flank. A side surface portion (15) of the peripheral side surface adjacent to at least a part of the cutting edge (6) includes a first flank portion (18) adjacent to the cutting edge, a second flank portion (19), a third flank portion (20), and a fourth flank portion (21) in this order from the first end surface side toward the second end surface side.