Drilling Needle Head Geometry for Straight Wood Testing Channels
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Solution Overview
Problem
Conventional drilling needles deviate from the intended axial feed direction when penetrating wooden objects at angles other than 90°, leading to non-straight channels and potential missed detection of rotting areas.
Innovation Solution
A drilling needle with a specifically designed head featuring a flattened wedge section, cutting edges, and relief surfaces that minimize drifting, allowing for reliable straight drilling at angles between 15° and 45° 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° to the object axis, then the ability to reach rotting areas below ground level is improved, but the drilling needle drifts from the intended axial feed direction, resulting in non-straight channels and potential missed detection
Solution Approach 1:
The drilling needle head features asymmetric relief surfaces with different relief grinding angles (α1 and α2) where α1 - α2 is between 2° and 10°. This asymmetric design creates different cutting characteristics on each side of the needle, generating lateral forces that counteract the drifting tendency when drilling at oblique angles, thereby maintaining straight drilling channels while enabling penetration angles between 15° and 45° to the object axis
Solution Approach 2:
The invention modifies the geometric parameters of the drilling needle head, specifically the relief grinding angles (α1 and α2) and the difference between them (2° to 10°). By optimizing these angular parameters, the cutting edges create balanced lateral forces that prevent needle deflection during oblique penetration, enabling straight drilling at angles deviating from the perpendicular while maintaining channel straightness
2Ease of operation
If the drilling needle head has a larger rotational diameter than the shaft diameter, then uniform rotation and chip removal are improved, but the needle head complexity increases
Solution Approach 1:
The drilling needle head is segmented into distinct functional zones: a wedge section with two wedge surfaces for initial penetration and material displacement, and a cutting section with two cutting surfaces for primary material removal. This segmentation allows each zone to perform its specific function optimally while keeping the overall structure manageable and manufacturable
Solution Approach 2:
Different surfaces of the needle head are given different geometric properties tailored to their specific functions: the wedge surfaces have specific angles for penetration, the cutting surfaces have optimized angles for chip removal, and the relief surfaces have precise grinding angles (α1 and α2) for controlling rotation and lateral forces. This local optimization of surface qualities achieves uniform rotation and effective chip removal without requiring excessive overall complexity
Data Source
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AI summary
The present invention provides a drilling needle (10) which has a drilling needle head (1) which, at one end of a drilling needle shank (2), has a flattened wedge portion (K) with two wedge faces (3) and a cutter portion (S) with two cutting faces (8) which each adjoin one of the wedge faces (3) and adjoin one another at a top edge (4) which runs at a right angle to the axis of rotation (A) of the drilling needle shank (2). The drilling needle head (1) has on each side a relief face (7) which forms a cutting edge (5) with in each case one of the cutting faces (8). The cutting edge (5) forms, with the respective other one of the cutting faces (8), a secondary edge (6) which trails with respect to the direction of rotation (r). The relief angle (α), which is defined by a virtual straight line (h), which runs through the cutting edge corner (5.1) and a secondary edge corner (6.1), with a plane (E2) which extends through the axis of rotation (A) perpendicular to the top edge (4), lies in a range from 6° to 10°.