Ball End Mill Geometry for Efficient Finishing and Surface Quality
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Solution Overview
Problem
Existing end mills achieve high-efficiency machining but struggle to produce a high-quality finished surface, necessitating an improvement in both machining efficiency and surface quality.
Innovation Solution
An end mill design featuring a shaft-shaped main body with a chip discharge groove, a spherical bottom blade, and an outer peripheral blade with a convex rotation locus, increased twist angle, and specific rake angles, allowing for reduced cutting load and enhanced blade edge strength, enabling efficient machining and high-quality surface finishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotation locus of the outer peripheral blade is made into a large circular arc shape to increase pick feed, then machining efficiency is improved, but the quality of the finished surface deteriorates
Solution Approach 1:
The end mill blade is divided into two distinct functional parts: an outer peripheral blade for wall surface finishing and a bottom blade for corner finishing. This segmentation allows each part to be optimized independently - the outer peripheral blade with a large circular arc rotation locus for efficient wall surface machining, and the bottom blade with a spherical shape for precise corner finishing, thereby resolving the contradiction between machining efficiency and surface quality
Solution Approach 2:
The end mill is designed to perform multiple functions with a single tool - both wall surface finishing and corner finishing capabilities are integrated into one end mill. The outer peripheral blade handles wall surface machining while the bottom blade handles corner machining, enabling the tool to universally address different machining requirements without sacrificing either efficiency or quality
2Productivity
If the curvature radius of the outer peripheral blade rotation locus is increased for high-efficiency machining, then pick feed is improved, but blade edge strength deteriorates
Solution Approach 1:
The patent optimizes multiple geometric parameters of the outer peripheral blade simultaneously: setting the curvature radius of the rotation locus to 20-30 times the blade thickness, the twist angle to 20° or more, and the radial rake angle to -20° or more and 0° or less. This combination of parameter changes allows the blade to achieve both large pick feed capability and sufficient edge strength, resolving the contradiction between productivity and strength
3Productivity
If the twist angle of the outer peripheral blade is increased to improve machining efficiency, then cutting load is reduced, but blade stability deteriorates
Solution Approach 1:
The patent specifies a twist angle of 20° or more for the outer peripheral blade, which optimizes the balance between cutting performance and structural stability. This parameter setting, combined with the specific curvature radius and rake angle, allows the blade to achieve reduced cutting load and improved machining efficiency while maintaining adequate stability through the optimized geometric configuration
Data Source
AI summary
The present invention provides an end mill including: a shaft-shaped end mill main body; a chip discharge groove extending from a leading end to a trailing end in an axial direction of the end mill main body; a bottom blade which is provided at a leading end portion in the axial direction of the end mill main body and has a spherical shape in which a rotation locus around the axis has a center on the axis; and an outer peripheral blade which is provided along the chip discharge groove, and in which a rotation locus around the axis is convex outward. A curvature radius of the rotation locus of the outer peripheral blade is larger than a curvature radius of the rotation locus of the bottom blade. A twist angle of the outer peripheral blade is 20° or more.