Multi-Flute Ball End Mill Curvature Segmentation
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Solution Overview
Problem
Conventional multi-flute ball end mills face challenges in preventing chipping and fracture of ball edges, achieving smooth chip discharge, and maintaining cutting performance during high-feed rough machining of high-hardness materials like hot-forged steel.
Innovation Solution
The multi-flute ball end mill design features a configuration with increased chip pocket occupation area near the rotation center and improved edge rigidity, including specific curvature ratios and radial rake angles, to enhance chip discharge performance and reduce cutting resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the curvature radius of the first cutting portion is increased to improve cutting performance, then the occupation space of chip pocket decreases, but chip discharge performance deteriorates
Solution Approach 1:
The ball edge is divided into two distinct cutting portions: a first cutting portion with a smaller curvature radius (0.025D to 0.10D) for effective chip discharge, and a second cutting portion with a larger curvature radius for maintaining cutting performance. This segmentation allows each portion to optimize its function independently.
Solution Approach 2:
Different regions of the ball edge are assigned different curvature radii to achieve different local functions. The first cutting portion near the rotation center has a smaller curvature radius to create larger chip pockets for smooth chip discharge, while the second cutting portion has a larger curvature radius to maintain cutting effectiveness.
2Productivity
If the degree of curvature of ball edges is increased to improve chip discharge, then the cutting resistance increases markedly, but cutting performance degrades
Solution Approach 1:
The ball edge curvature is segmented into two portions with different curvature radii. The first cutting portion has a smaller curvature radius (0.025D to 0.10D) that provides adequate chip discharge capability without excessive curvature, while the second cutting portion has a larger curvature radius that maintains lower cutting resistance.
Solution Approach 2:
The curvature radius parameter is changed differently across different portions of the ball edge. By setting the first cutting portion curvature radius to 0.025D to 0.10D and the second cutting portion curvature radius to be larger, the patent optimizes the balance between chip discharge and cutting resistance.
3Productivity
If thinning is performed on lands of ball edges to create chip pockets, then chip discharge is improved, but the ball edges become prone to chipping and fracture
Solution Approach 1:
The land thickness is optimized locally in different regions. The first cutting portion has a land thickness of 0.02D to 0.06D that creates adequate chip pockets for discharge, while the second cutting portion has a larger land thickness that maintains ball edge strength and resistance to chipping and fracture.
Solution Approach 2:
The ball edge structure is segmented into cutting portions and lands with different dimensional characteristics. The cutting portions have optimized curvature radii for cutting performance, while the lands have sufficient thickness to prevent structural failure.
Data Source
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AI summary
A multi-flute ball end mill of the present invention includes: a shank portion configured to rotate about a rotational axis; a cutting edge portion; three or more ball edges formed on the cutting edge portion; gashes formed between the ball edges; peripheral cutting edges continuous with end portions of the ball edges on the shank portion side; and flutes formed between the peripheral cutting edges continuously with the gashes. The degree of curvature of the ball edges is 35% to 55%. Each of the gashes includes four faces of a rake face of each of the ball edges, a gash wall face, a first gash face, and a second gash face. The second gash face is formed such that the closer the second gash face is to the rotation center point, the more inwardly the second gash face enters a second face of each of the ball edges.