Helical Eight-Flute End Mill for Deep Wall Machining Accuracy
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Solution Overview
Problem
In contour machining of vertical walls, the use of end mills with long cut lengths leads to insufficient rigidity, resulting in reduced machining accuracy and increased costs due to frequent zero cutting and multiple axial movements.
Innovation Solution
An end mill with eight peripheral cutting edges of larger outer diameter, twisted helically around the central axis, where the number of simultaneous contact cutting edges is maintained at approximately one in the lower half region to minimize vibration and improve accuracy, allowing for longer cut lengths and reduced zero cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an end mill with long cut length is used to machine deep vertical walls, then the machining efficiency is improved, but the rigidity of the end mill becomes insufficient, causing tool deflection and reduced machining accuracy
Solution Approach 1:
The end mill is designed with multiple peripheral cutting edges (at least three) arranged circumferentially, dividing the cutting action into multiple simultaneous contact points. This segmentation allows the tool to maintain rigidity while achieving deep cuts, as the distributed cutting edges share the cutting load and reduce individual edge deflection.
Solution Approach 2:
The invention applies different geometric properties to different parts of the cutting edge. The peripheral cutting edges are designed with specific helical angles and curvature radii that optimize both rigidity and cutting performance. The neck portion has a controlled outer diameter that balances rigidity with chip evacuation, creating local quality variations that resolve the contradiction between long cut length and tool rigidity.
2Productivity
If the cut depth is set to the entire length of the peripheral cutting edge, then the machining speed is improved, but the tool is likely to be deflected during machining, reducing machining accuracy
Solution Approach 1:
The end mill design incorporates dynamic balance through its geometric parameters. The helical angle of the peripheral cutting edges and the curvature radius of the neck portion are optimized to distribute cutting forces dynamically during rotation, preventing tool deflection even at full cut depth. This dynamic force distribution allows maintaining both high machining speed and accuracy.
3Manufacturing precision
If zero cutting is repeatedly performed to obtain high-accuracy finished surface quality, then the machining accuracy is improved, but the machining time is increased, raising machining cost
Solution Approach 1:
The multiple peripheral cutting edges enable continuous effective cutting action without requiring zero cutting interruptions. The simultaneous engagement of multiple cutting edges maintains consistent surface quality throughout the cutting process, eliminating the need for repeated zero cutting passes and reducing total machining time while preserving surface quality.
4Manufacturing precision
If the cut depth is reduced to improve accuracy, then the machining accuracy is improved, but the end mill must be moved many times in the axial direction, increasing machining time
Solution Approach 1:
The invention merges multiple cutting edges into a single tool body, allowing deep cuts to be achieved in fewer axial movements. The simultaneous action of multiple peripheral cutting edges consolidates what would otherwise require multiple separate cutting passes, reducing the number of axial movements needed while maintaining high machining accuracy.
Data Source
AI summary
In an end mill, eight peripheral cutting edges having a helical shape and a larger outer diameter than that of a shaft portion are in a cutting portion in a circumferential direction. For one peripheral cutting edge of the eight peripheral cutting edges, when a cut length of the peripheral cutting edge along an axial direction is L, a twist angle of the peripheral cutting edge is θ, and a circumferential distance at a lower end of the peripheral cutting edge between the peripheral cutting edge and another peripheral cutting edge adjacent to a tool rotation direction rear side of the peripheral cutting edge is a, n expressed by the following equation is approximately 1 for all of the eight peripheral cutting edges in at least a half region of the cut length from the lower end of the peripheral cutting edge.n=(L×tan θ)/(2×a)