Convex-Tip Ball End Mill for High-Gloss Flat Surface Finishing
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Solution Overview
Problem
Ball end mills with chisel edges struggle to achieve high-gloss machined surfaces on flat surfaces orthogonal to the tool rotation axis, often requiring a polishing step due to gouging and poor cutting performance at the tool tip.
Innovation Solution
A ball end mill design featuring a convex tip surface intersecting the tool rotation axis, with central cutting blades continuous with the ball blades, eliminating the chisel edge and enhancing cutting performance and surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a chisel edge is used at the tool tip, then the tool can cut flat surfaces orthogonal to the rotation axis, but the machined surface quality deteriorates due to gouging and adhesion
Solution Approach 1:
The invention removes the chisel edge from the tool tip design. By extracting this problematic feature, the patent eliminates the source of gouging and adhesion issues while maintaining the ability to cut flat surfaces through the ball blade geometry alone
Solution Approach 2:
Instead of using a chisel edge (obtuse angle intersection) at the tool tip, the invention inverts the approach by creating a sharp edge through the intersection of the ball blade rake face with the tip surface. This reverses the geometric configuration from obtuse to acute angle, fundamentally changing the cutting mechanism at the tool tip
2Device complexity
If a chisel edge with large negative rake angle is used, then the tool structure is simplified, but the cutting performance deteriorates due to gouging
Solution Approach 1:
The chisel edge is completely removed from the tool design. This extraction eliminates the large negative rake angle problem while maintaining structural simplicity through the continuous ridgeline configuration of the ball blade with the tip surface
Solution Approach 2:
The invention changes the rake angle parameter at the tool tip from large negative (chisel edge) to positive or zero by forming the sharp edge through the intersection of the ball blade rake face with the convex tip surface. This parameter change fundamentally improves cutting performance without compromising structural simplicity
3Strength
If the tip portion is designed with a chisel edge, then the tool can maintain structural integrity, but the machined surface requires additional polishing steps
Solution Approach 1:
By removing the chisel edge, the invention eliminates the need for post-processing polishing steps. The sharp edge formed by the ball blade rake face intersection with the tip surface provides sufficient structural integrity while achieving the desired surface finish in a single cutting operation
Solution Approach 2:
The ball blade geometry serves multiple functions simultaneously: it provides the cutting edge, maintains structural integrity, and produces the required surface finish. This multi-functionality eliminates the need for separate polishing operations, improving productivity
Data Source
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AI summary
An object of the present invention is to provide a ball end mill suitable for finishing, with which a high-gloss machined surface is obtained in the cutting of a flat surface orthogonal to a tool rotation axis, such as a bottom surface of a die, using a tool tip portion, and with which it is possible to omit a polishing step or reduce the number of polishing man-hours. The present invention is a ball end mill in which a plurality of swarf discharge grooves 2 opened at a tip end and leading from a tool-tip-end side to a tool-base-end side are formed in an outer periphery of a tool body 1, and ball blades 5 are provided at intersection ridgelines between rake faces 3 of the swarf discharge grooves 2 and tip-end flanks 4 of the tool body 1, wherein a convex tip surface 6 intersecting a tool rotation axis a of the tool body 1 is provided at a tool tip portion, and intersection ridgelines between the tip surface 6 and the rake faces 3 are configured as central cutting blades 7 continuous with the ball blades 5.