Reamer Drill Geometry for Low-Rigidity Hole Accuracy
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Solution Overview
Problem
Conventional drills with continuously changing point and relief angles struggle to maintain high accuracy when used with handheld tools, leading to suboptimal hole quality due to vibration and deflection, especially when drilling composite materials or metals with low spindle rigidity.
Innovation Solution
A drill design featuring first cutting edges with continuously decreasing point and relief angles, accompanied by reamer cutting edges with controlled point and relief angles, and a deflection reducer (holding part) to minimize deflection and ensure accurate hole machining across varying spindle rigidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a drill with continuously changing point angle and relief angle is used, then manufacturing precision and hole quality are improved when using high-rigidity spindles, but vibration and deflection increase when using low-rigidity spindles or handheld tools
Solution Approach 1:
The drill is divided into distinct functional zones: a tip cutting edge portion with specific point angles for initial material removal, and a body portion with different geometric characteristics for stable cutting. This segmentation allows each portion to optimize its function independently, reducing overall vibration while maintaining hole quality.
Solution Approach 2:
Different portions of the drill have locally optimized geometric properties. The tip cutting edge has a point angle between 60-90 degrees suitable for penetrating and cutting material, while the body portion has a smaller point angle and specific relief angles (5-15 degrees on the cutting edge, 10-20 degrees on the flank face) that reduce friction and vibration during the main cutting process.
2Manufacturing precision
If multiple cutting edges are used to improve hole quality, then manufacturing precision is improved, but vibration increases when using low-rigidity spindles
Solution Approach 1:
The drill geometry parameters are specifically optimized to change from the tip toward the body. The point angle decreases from 60-90 degrees at the tip to a smaller angle in the body, while relief angles are introduced (5-15 degrees on cutting edge, 10-20 degrees on flank face). These parameter changes reduce cutting resistance and vibration, allowing multiple cutting edges to work harmoniously even on low-rigidity spindles.
Data Source
Figure 1
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Figure 5~6
AI summary
According to one embodiment, a drill (1) includes the first cutting edges (5), the second cutting edges (6) and a deflection reducer (7). The first cutting edges (5) drill a prepared hole to a workpiece (W). The first cutting edges (6) are formed at a tip side of the drill (1). The first point angle (a) and each first relief angle (γ1) of the first cutting edges (5) continuously or intermittently decrease from the tip side toward a rear end side of the drill (1). The second cutting edges (6) ream the prepared hole. The second cutting edges (6) are formed at positions away at the rear end side from the first cutting edges (5). The second cutting edges (6) have the second relief angles (γ2) at a maximum diameter position. The deflection reducer (7) reduces deflection of the second cutting edges (6). The deflection reducer (7) is formed between the first cutting edges (5) and the second cutting edges (6). The deflection reducer (7) is inserted into the prepared hole.