Wood Drilling Needle Geometry for Straight Angled Bore Paths
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Solution Overview
Problem
Conventional drilling needles deviate from the intended axial feed direction when penetration angles deviate from 90°, leading to non-straight drilling channels that may miss rot areas in wooden poles.
Innovation Solution
A drilling needle with a specifically designed head featuring a flattened wedge portion, rounded flank segments, and angled cutting edges, allowing for precise straight-line drilling at angles of 15° to 45° relative to the object axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional drilling needles are used at penetration angles deviating from 90°, then the drilling needle can reach sections below ground level, but the needle drifts from the intended axial feed direction creating non-straight drilling channels
Solution Approach 1:
The drilling needle head features asymmetric relief faces with different relief angles (α1 and α2) relative to the cutting faces. This asymmetric geometry creates differential cutting forces that actively counteract the lateral drift tendency when drilling at angles deviating from 90°, thereby maintaining straight drilling channels while enabling versatile penetration angles ranging from 15° to 45° relative to ground level
Solution Approach 2:
The invention modifies the geometric parameters of the drilling needle head, specifically the relief angles (α1 = 5°-15°, α2 = 15°-25°) and the angle between cutting faces (β = 80°-100°), to optimize the cutting behavior and force distribution. These parameter changes enable the needle to maintain structural integrity and drilling precision across a wide range of penetration angles without drifting
2Ease of operation
If the drilling needle head has a larger diameter of rotation than the shank diameter, then uniform rotation and chip displacement are improved, but the needle becomes more prone to deviation from axial feed direction
Solution Approach 1:
The drilling needle head exhibits local quality variations through its asymmetric relief face design, where different regions (cutting edges vs. secondary edges) have different relief angles. This localized geometric differentiation ensures that the larger diameter portion provides uniform rotation and effective chip displacement, while the asymmetric relief geometry locally compensates for lateral forces to maintain axial feed direction stability
Data Source
AI summary
A drilling needle includes a needle head at one end of a needle shank. The needle head has a flattened wedge portion with two wedge faces and a cutter portion with two cutting faces, which each adjoin one of the wedge faces and adjoin one another at a top edge that runs at a right angle to an axis of rotation. The needle head has on each side a relief face, which forms a cutting edge with each of the cutting faces. The cutting edge forms, with the respective other one of the cutting faces, a secondary edge that trails with respect to the direction of rotation. A relief angle, spanned by a virtual straight line through the cutting edge corner and a secondary edge and a plane that extends perpendicular to the top edge in the axis of rotation, lies in a range from 6° to 10°.