Concave-Flute Drill Bit for Round Hole Accuracy
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Solution Overview
Problem
Conventional drill bits often cause off-axis lateral loading, leading to side cutting and the creation of out-of-round holes in organic materials like bone, which can result in uneven fastening forces due to the shape of the hole being drilled.
Innovation Solution
A drill bit design featuring a cylindrical shank with longitudinally extending flutes that have concave cross-sections on their edges, formed by grinding the cylindrical surface at a specific helical angle, reducing the sharpness and preventing side cutting by creating a concave surface that intersects with the cutting tip, thereby maintaining a round hole shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drill bits with sharp helical flutes are used, then material removal efficiency is improved, but side cutting occurs causing out-of-round holes
Solution Approach 1:
The flute edges are modified with concave cross-sections that create rounded leading edges, while the rest of the flute structure maintains its helical configuration for efficient material removal. This localized modification at the critical cutting edge prevents side cutting without compromising overall material removal efficiency
Solution Approach 2:
The flute edges are formed with concave cross-sections that create curved, rounded leading edges instead of sharp edges. This curvature allows the cutting edge to engage the workpiece more gradually and uniformly, preventing the lateral loading that causes side cutting and out-of-round holes
2Power
If sharp flute edges are used for effective cutting, then cutting performance is improved, but off-axis lateral loading increases causing side cutting
Solution Approach 1:
The concave cross-section modification is applied specifically to the leading edges of the helical flutes where cutting occurs, while the rest of the flute structure maintains its original configuration. This localized change addresses the lateral loading issue at the cutting edge without affecting the overall cutting performance
Solution Approach 2:
The geometry of the flute edges is changed from sharp to concave with rounded leading edges. This parameter change in the edge geometry modifies how the flutes engage the workpiece, distributing cutting forces more evenly and reducing off-axis lateral loading while maintaining effective cutting
Data Source
AI summary
A drill bit for forming a round hole in a workpiece, includes a cylindrical shank having a longitudinally extending fluted portion with opposed first and second ends, and defining a longitudinal axis about which the shank is rotatable. The fluted portion includes opposed helical flutes formed in the cylindrical surface of the fluted portion of the shank and extending longitudinally along and between the first and second ends of the fluted portion. The helical flutes each define a concave surface intersecting with the cylindrical surface of the shank to form opposed flute edges. The first end of the fluted portion includes a cutting tip intersecting the helical flutes, wherein at least one of the flute edges has a concave cross-section extending from the second end toward the first end of the fluted portion.