Variable-Rake Finish End Mill for Deep Shouldering Milling
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Solution Overview
Problem
Conventional end mills face challenges in effectively milling deep shouldering operations due to increased vibration and reduced tool life when dealing with high hardness materials, as they tend to bend and experience chip evacuation issues with longer lengths and harder materials.
Innovation Solution
A deep shouldering end mill with an effective cutting length greater than 2.5D, featuring a plurality of teeth with varying radial rake angles and increasing flute depth from the shank, which reduces vibration and enhances chip evacuation by combining enlarged flute depth with significantly different rake angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the effective cutting length of the end mill is increased to enable deep shouldering milling, then the milling depth capability is improved, but vibration increases and tool life decreases
Solution Approach 1:
The patent applies local quality by varying the radial rake angle for different teeth positioned at different locations along the cutting length. Teeth closer to the cutting end face have different rake angles than those farther away, allowing each tooth to be optimized for its specific operating conditions and reducing overall vibration
Solution Approach 2:
The patent implements asymmetry by using non-uniform radial rake angles across the teeth rather than a symmetric uniform design. This asymmetric configuration creates varying cutting forces that reduce vibration and improve stability during deep shouldering milling operations
2Length of moving object
If the effective cutting length is increased to mill deeper shouldering, then the milling depth capability is improved, but surface finish quality deteriorates due to increased vibration
Solution Approach 1:
The varying radial rake angles at different tooth positions create localized optimization where each tooth contributes to reduced vibration, thereby maintaining surface finish quality even at increased cutting lengths beyond 2.5D
Solution Approach 2:
The patent directly addresses mechanical vibration by using differentiated radial rake angles to create varying cutting forces that counteract resonant vibrations, ensuring stable surface finish quality during deep shouldering milling
3Volume of moving object
If the flute depth is increased to accommodate longer cutting length, then the chip evacuation space is improved, but chip abutment against the end mill increases vibration
Solution Approach 1:
The patent applies local quality by providing different radial rake angles for teeth at different positions, which optimizes chip flow characteristics at each location and reduces chip abutment vibrations while maintaining adequate flute depth for chip evacuation
Data Source
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AI summary
A finish end mill configured for rotating about a central rotation axis (AR) defining opposite axially forward and rearward directions (DF, DR), and opposite rotational preceding and succeeding directions (DP, DS), the preceding direction (DP) being the cutting direction, the end mill comprising a shank portion; and a cutting portion extending forward from the shank portion to a cutting end face, the cutting portion comprising an effective cutting length (LE), a diameter (DE), a plurality of integrally formed teeth, and a plurality of flutes alternating with the plurality of teeth, each flute having a helix angle and a flute depth each tooth comprising a rake surface, a relief surface succeeding the rake surface and having a relief surface width measurable in a plane perpendicular to the rotation axis (AR), a cutting edge formed at an intersection of the rake and relief surfaces, a relief edge spaced apart from the cutting edge and formed at an intersection of the relief surface and a flute surface of the flute succeeding the tooth and a tooth area defined between a first radial line extending from the cutting edge to the central rotation axis and a second radial line extending from the central rotation axis to a nadir of the succeeding flute, characterized in that the plurality of integrally formed teeth are five or more teeth at an axial location in a front half of the effective cutting length the teeth have an average radial rake angle value, with one or more teeth having a smallest radial rake angle value, and one or more teeth having a largest radial rake angle value, the cutting portion has an effective cutting length greater than 2.5D, at least some of the teeth with different radial rake angle values have values different from all other non-identical values by 2° or more and each flute of the plurality of flutes has an increasing depth with increasing distance from the shank.