End Mill Gash Connecting Face Curvature
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Solution Overview
Problem
End mills face issues with chip clogging and stress concentration due to narrow intersecting angles between cutting edge rake faces and gash faces, leading to reduced rigidity and potential fractures, especially when multiple cutting edges are present.
Innovation Solution
The end mill design features connecting faces with specific curvature radii between the end cutting edge rake face, gash bottom face, and gash wall face, where the first connecting face has a larger radius of curvature than the second, allowing for smooth chip flow and reduced stress concentration without increasing gash width, thereby maintaining rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the gash width is increased to improve chip discharge performance, then chip clogging is reduced, but the rigidity of the end mill body deteriorates
Solution Approach 1:
The gash is divided into multiple faces (first gash face, second gash face, third gash face, fourth gash face) that connect to the end cutting edge rake face through intersecting ridgelines. This segmentation allows each face to be optimized independently for chip flow while maintaining overall structural integrity and rigidity of the end mill body.
Solution Approach 2:
Different gash faces have different geometric configurations optimized for their specific functions. The first and second gash faces have specific inclination angles relative to the end cutting edge rake face, while the third and fourth gash faces have different configurations. This local optimization enables effective chip discharge in specific regions without compromising the overall rigidity of the end mill body.
2Ease of operation
If the intersecting ridgeline has a concave curved shape to improve chip flow, then chip clogging is reduced, but stress concentration increases leading to potential fractures
Solution Approach 1:
The intersecting ridgelines are designed with specific curvature characteristics. The first and second intersecting ridgelines have curvature radii that are optimized to enable smooth chip flow along the gash faces while avoiding sharp corners that would cause stress concentration. The third and fourth intersecting ridgelines similarly incorporate curvature to maintain chip flow smoothness while distributing stresses.
Solution Approach 2:
The curvature radii of the intersecting ridgelines are specifically controlled within certain ranges. By optimizing these geometric parameters, the design achieves a balance between smooth chip flow (requiring adequate curvature) and stress distribution (requiring avoidance of excessive curvature that creates stress concentrations).
Data Source
AI summary
An end mill having a gash formed in a top portion of a flute. In a cross-section perpendicular to an intersecting ridgeline between an end cutting edge rake face and a gash bottom face of the gash, the gash bottom face and the end cutting edge rake face, and the gash bottom face and the gash wall face are respectively connected together by first and second connecting faces. The connecting faces have a form which either is a concave curve or a substantially concave curve formed with straight lines. A radius of curvature of the concave curve or the radius of a circle inscribed within straight lines forming the substantially concave curve about the front connecting face is larger than a radius of curvature of the concave curve or the radius of a circle inscribed within the straight lines forming the substantially concave curve about the second connecting face.