Curved Peripheral Cutting Edge End Mill for Vertical Wall Finishing
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Solution Overview
Problem
Ball end mills face inefficiencies when cutting vertical walls with small inclination angles due to increased pitch leading to surface roughness and higher costs with larger tool diameters, necessitating reduced pitch and increased rotational force.
Innovation Solution
An end mill design with a convex curved peripheral cutting edge and specific helix and radial rake angles, allowing for increased axial movement pitch without protruding boundaries and reduced cutting resistance, enhancing machining efficiency and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the movement pitch in axial direction is increased to improve machining efficiency, then productivity increases, but boundary portions between overlapping cutting surfaces protrude and machined surface roughness deteriorates
Solution Approach 1:
The invention applies curvature to the rotation locus of the peripheral cutting edge, forming a convex curved shape with a specific radius ratio (0.55-0.65 times the tool diameter) instead of a straight or hemispherical path. This curved trajectory allows the cutting edge to smoothly bridge between overlapping passes, preventing boundary protrusions while enabling larger movement pitches and improving both surface quality and machining efficiency
2Strength
If the tool diameter is increased to improve cutting performance, then cutting capability increases, but the end mill main body size increases requiring increased rotational driving force and cost increases
Solution Approach 1:
The invention changes the geometric parameters of the cutting edge trajectory by defining a specific curvature radius ratio (0.55-0.65 times tool diameter) and combining it with optimized helix angles (30-45 degrees) and rake angles. These parameter optimizations improve cutting performance and edge strength without requiring increased tool diameter, thereby maintaining acceptable rotational driving force requirements
3Productivity
If the movement pitch in axial direction is increased, then machining efficiency improves, but edge strength requirements increase to prevent boundary protrusion
Solution Approach 1:
The convex curved rotation locus with optimized radius distributes cutting loads more evenly along the peripheral cutting edge compared to straight or hemispherical paths. This curvature design reduces stress concentration at boundary portions, maintaining edge strength integrity even when larger movement pitches are used for improved machining efficiency
4Force
If the helix angle and radial rake angle are optimized to reduce cutting load, then cutting resistance decreases, but edge sharpness and strength must be balanced
Solution Approach 1:
The invention optimizes the combination of helix angles (30-45 degrees) and radial rake angles to achieve the best balance between cutting load reduction and edge strength maintenance. This parameter optimization, combined with the curved rotation locus, allows the peripheral cutting edge to maintain high sharpness while securing sufficient edge strength for efficient cutting with reduced cutting resistance
Data Source
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AI summary
An end mill includes an end mill main body (1) which is rotated in around an axis O in an end mill rotation direction T, a chip discharge flute (4) which is formed on the outer periphery of a leading end portion of the end mill main body (1), and a cutting edge (5) which has a peripheral cutting edge (6) formed on the outer peripheral ridge portion of a wall surface of the chip discharge flute (4) facing the end mill rotation direction T. In the peripheral cutting edge (6), a cross section along the axis O of a rotation locus around the axis O has a convex curved shape which protrudes toward an outer peripheral side of the end mill main body (1). A curvature radius R of the convex curve is set to be larger than 1/2 of an outer diameter D of the cutting edge (5) and 3 times or less the outer diameter D. A helix angle β of the peripheral cutting edge (6) is 20 degree or more, and a radial rake angle of the peripheral cutting edge (6) is -20 degree or more and 0 degree or less.