End Mill With Varying Helix Angles To Reduce Vibrations
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Solution Overview
Problem
Existing end mills experience vibrations and resonance issues due to uneven circumferential angular distances between cutting edges, leading to inefficient machining and uneven load distribution, which complicates production and reduces tool stability.
Innovation Solution
The end mill design features alternating helix angles for main cutting edges, with specific angular distances that vary minimally in certain axial positions, ensuring all circumferential angular distances are identical in any plane perpendicular to the axis, and incorporates a varying axial profile for improved chip breaking and load distribution, along with a conical core diameter for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all circumferential angular distances between cutting edges are made identical in every plane perpendicular to the axis, then vibration prevention is improved, but the design complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent applies local quality by making the circumferential angular distances identical only in a specific axial plane (the front end plane), while allowing different distances in other planes. This localized approach to achieving equal angular distribution resolves the contradiction by providing vibration prevention where it matters most (at the cutting front) without requiring complex design throughout the entire tool length.
Solution Approach 2:
The cutting edges are segmented into two groups with different helix angles, where odd-numbered edges have one helix angle and even-numbered edges have another. This segmentation allows the front end plane to achieve identical angular distances while other planes naturally have different distances, simplifying the overall design while maintaining vibration prevention.
2Reliability
If cutting edges have different helix angles to achieve identical circumferential distances at the front end, then vibration resistance improves, but load distribution uniformity deteriorates
Solution Approach 1:
The different helix angles are applied locally to achieve the critical identical angular distances at the front end plane, while accepting that load distribution may vary in other axial positions. This localized optimization resolves the contradiction by prioritizing vibration resistance at the cutting front where it is most critical.
Data Source
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AI summary
The present invention relates to an end mill, primarily for coarse machining of metallic work pieces, comprising an even number of main flutes (1-4) that spiral around the periphery of the mill, said flutes having a relatively smaller and a relatively larger helix angle relative to the axis of the mill and wherein uneven-numbered main flutes are defined in that they include the smaller helix angle with the axis. Directly at the end face, the distances between peripheral angles (a1, a2) of the successive main flutes in the direction of rotation are smaller between the uneven-numbered main flutes (1, 3) and the subsequent even-numbered main flutes (2, 4) than the distances between peripheral angles (a2, a4) between the even-numbered main flutes (2, 4) and the subsequent uneven-numbered main flutes (1, 3). In order to provide an end mill with the features mentioned above which is better able to prevent vibrations of the tool due to intermittent engagement with a work piece, according to the invention all distances between peripheral angles at the end face of the mill are different from one another.