Two-Flute Ball End Mill Flank Geometry for Scratch-Free Finishing
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Solution Overview
Problem
In machining extremely hard workpieces like cemented carbide, existing ball end mills face challenges in achieving high-quality machined surfaces due to issues such as deposited metals and scratches, especially near the rotation axis.
Innovation Solution
The ball end mill is designed with a configuration where the chisel edge front region is composed only of the first flank surface, eliminating the boundary portion between the first and second flank surfaces. This design reduces the likelihood of chips being pressed against the machined surface and improves cutting performance by minimizing wedge angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the groove wall surface shape is optimized for chip discharge (as in Patent Document 1), then chip discharge performance is improved and damages near the rotation axis are suppressed, but deposited metals occur on the machined surface in finishing operations
Solution Approach 1:
The flank surface is divided into two distinct regions: a first flank surface with a smaller clearance angle for chip discharge, and a second flank surface with a larger clearance angle for producing high-quality machined surfaces. This segmentation allows each region to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the flank surface are given different clearance angles tailored to their specific functions. The first flank surface near the chisel edge has a smaller clearance angle to facilitate chip discharge, while the second flank surface has a larger clearance angle to prevent deposited metals and improve surface finish.
2Manufacturing precision
If the chisel edge shape and clearance angle are adjusted to improve surface finish (as in Patent Documents 2 and 3), then machined surface roughness is improved, but deposited metals or scratches may still occur
Solution Approach 1:
The flank surface is segmented into two zones with different clearance angles. The first flank surface handles chip discharge while the second flank surface, with its larger clearance angle, prevents deposited metals and scratches on the machined surface.
Solution Approach 2:
The clearance angle parameter is changed across different regions of the flank surface. By increasing the clearance angle in the second flank surface region, the tool prevents deposited metals and scratches while maintaining effective chip discharge in the first flank surface region.
3Device complexity
If a single flank surface with uniform clearance angle is used, then the structure is simple, but it cannot simultaneously achieve good chip discharge and high-quality surface finish
Solution Approach 1:
The flank surface is divided into two distinct surfaces with different clearance angles. This segmentation enables the tool to simultaneously achieve effective chip discharge and high-quality surface finish, overcoming the limitations of a uniform clearance angle design.
Solution Approach 2:
Different regions of the flank surface are assigned different clearance angle values. The first flank surface has a smaller clearance angle optimized for chip discharge, while the second flank surface has a larger clearance angle optimized for surface finish quality.
Data Source
AI summary
A two-flute ball end mill includes a cutting edge that is formed at an intersection ridge line between a groove wall surface of a gash groove and a flank surface; and the flank surface includes a first flank surface that forms a chisel edge and a second flank surface that extends from the first flank surface to a rear side in a rotation direction with a larger clearance angle. In a case where, as seen from a tip side in an axial direction, an intersection point between one cutting edge of two cutting edges and the chisel edge is defined as a first intersection point, and an intersection point between a flank surface boundary line between the first flank surface and the second flank surface of the other cutting edge of the cutting edges and the groove wall surface is defined as a second intersection point.