Indexable Milling Insert Vibration Damping Geometry
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Solution Overview
Problem
High-capacity milling inserts are prone to uncontrolled vibrations, especially when operating at large cutting depths, leading to tool and machine breakdowns, particularly in slender tools like shank-end mills, which can result in damage, rejection of workpieces, and safety risks.
Innovation Solution
A milling insert with a second clearance surface of uniform width, between 0.05 mm and 0.3 mm, is designed between the main cutting edge and the first clearance surface, featuring a nominal clearance angle that decreases successively from the initial end to the corner edge, providing effective vibration damping without excessive heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If milling inserts are designed with positive cutting geometry and acute clearance angles for high cutting capacity, then material removal efficiency is improved, but uncontrolled vibrations occur at large cutting depths
Solution Approach 1:
The invention applies different clearance angles to different portions of the cutting edge. The first portion (from initial end to corner edge) has a larger first clearance angle for efficient material removal, while the second portion (from corner edge along main edge) has a smaller second clearance angle to provide vibration damping. This local differentiation allows the cutting edge to simultaneously achieve high productivity and vibration control.
Solution Approach 2:
The cutting edge is segmented into two distinct portions with different geometric characteristics. The first portion optimizes for cutting capacity with acute clearance angles, while the second portion optimizes for vibration damping with smaller clearance angles. This segmentation allows each portion to perform its specific function without interfering with the other.
2Productivity
If cutting depth is increased to enhance material removal volume, then productivity is improved, but vibrations grow in an uncontrolled way leading to tool breakdown
Solution Approach 1:
The invention incorporates vibration-damping geometry (the second portion with smaller clearance angle) in advance, before vibrations can develop into uncontrolled oscillations. This preliminary anti-action counteracts the tendency toward vibration at the source, allowing increased cutting depths to be maintained without risking tool breakdown or workpiece rejection.
3Manufacturing precision
If main edge is given convexly curved shape for smooth surface generation, then surface quality is improved, but vibration damping capability is reduced
Solution Approach 1:
The convex curvature is applied only to the first portion of the main edge where smooth surface generation is required, while the second portion maintains a different geometry optimized for vibration damping. This local differentiation allows the cutting edge to simultaneously achieve surface quality and vibration resistance.
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 dampens vibrations, allowing for increased axial cutting depth and removal volume without risking tool or machine damage, while maintaining efficient machining performance and minimizing heat generation.
Implementation Method 1
a second clearance surface being formed between the cutting edge line and the first clearance surface, which second clearance surface has a width of at most 0,3 mm and a nominal second clearance angle that is smaller than the first clearance angle
Data Source
AI summary
The invention relates to an indexable milling insert of the type that comprises an upperside (11), an underside (12) and two cutting edges (6), which individually include a cutting edge line (13) and are formed between a chip surface (14) included in the upperside (11) and a clearance surface (15) extending between the upperside and the underside, which clearance surface has an acute, nominal clearance angle. Furthermore, the individual cutting edge (6) comprises a main edge (18), which extends from an initial end (21) to a corner edge (19) having a smaller radius of curvature than the main edge (18). Between the cutting edge line (13) and the first clearance surface (15), a second clearance surface (26) of uniform width is formed, which has a width of at most 0,3 mm and the clearance angle of which is without exception smaller than the clearance angle of the first clearance surface (15) and decreases successively in the direction from the initial end (21) toward the corner edge (19). Thanks to the second clearance surface, tendencies to vibrations will be counteracted without substantially increasing harmful generation of heat.