Asymmetric Ball End Mill Edge Spacing for Smoother Machining
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Solution Overview
Problem
Ball end mills with periodically disposed long cutting edges often experience chatter vibration due to changing cutting loads, which affects the smoothness of machined surfaces.
Innovation Solution
An end mill design featuring a main body with a combination of long and short cutting edges, where the number of short cutting edges between long cutting edges is varied (N1 ≠ N2), and the cutting edges are arranged to minimize coincident contact times, reducing chatter vibration and enhancing surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If long cutting edges are periodically disposed in ball end mills, then chatter vibration is reduced and surface smoothness is improved, but cutting load changes periodically causing vibration
Solution Approach 1:
The patent applies asymmetry by making the distribution of short cutting edges asymmetric with respect to long cutting edges. Specifically, the number of short cutting edges on the front side (N1) differs from the number on the rear side (N2) of each long cutting edge. This asymmetric arrangement prevents periodic coincidence of cutting edge contacts, eliminating the periodic cutting load variations that cause chatter vibration, while still maintaining multiple cutting edges for smooth surface finishing.
2Productivity
If multiple long cutting edges are used, then cutting efficiency is improved, but coincident contact times cause vibration
Solution Approach 1:
The patent resolves the vibration issue caused by multiple long cutting edges by introducing asymmetric distribution of short cutting edges. The different numbers of short cutting edges (N1 ≠ N2) on either side of each long cutting edge ensure that the contact times of different cutting edges do not coincide periodically. This maintains the productivity benefit of multiple cutting edges while eliminating the harmful vibration through asymmetric spacing.
Data Source
AI summary
An end mill may include a main body having a bar shape extending from a first end to a second end. The main body may include a plurality of cutting edges located at the first end, and a plurality of flutes individually extended from the cutting edges toward the second end. The cutting edges may include a plurality of long cutting edges and a plurality of short cutting edges. The long cutting edges include a first long cutting edge. N1 is the number of the short cutting edges located forwards in a rotation direction with respect to the first long cutting edge. N2 is the number of the short cutting edges located backwards, opposite the rotation direction with respect to the first long cutting edge. And, N1 is different from N2.