Threaded Flat Drill Bit Geometry for Nail-Resistant Wood Drilling
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Solution Overview
Problem
Existing flat drill bits for cordless hand-held electric power tools face issues with nail fracture and inefficient torque coordination during drilling in wood materials, particularly when encountering hidden nails.
Innovation Solution
A flat drill bit design featuring a stem body with a cut flute part and a threaded guiding part, where the cutting edges are inclined at an angle of 84° to 86° relative to the longitudinal axis, and the guiding part has a cone shape with external threads and a specific pitch, ensuring smooth transition from guiding to cutting and enhanced strength through symmetrical longitudinal wings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the cutting edge is perpendicular to the longitudinal axis (conventional design), then the drilling speed is fast, but the cutting edge easily fractures when striking nails
Solution Approach 1:
The patent changes the critical parameter of cutting edge orientation from perpendicular (0°) to inclined (84-86° relative to longitudinal axis, or 4-6° from perpendicular). This parameter change allows the cutting edge to strike nails at a glancing angle, reducing impact forces and preventing fracture while maintaining drilling efficiency through the optimized inclination angle
2Strength
If the threaded guiding part has a large diameter, then the torque requirement is high, but cordless tools have limited power output
Solution Approach 1:
The patent optimizes the diameter parameter of the threaded guiding part to be smaller than conventional designs. This reduction in diameter directly lowers the torque requirement, making the drill bit compatible with cordless hand-held tools that have limited power output, while the threading geometry ensures sufficient engagement and guiding function
3Reliability
If the cutting edge is inclined towards the shaft (downstream direction), then nail cutting is improved, but the cutting angle becomes too small for effective wood cutting
Solution Approach 1:
The patent precisely optimizes the inclination angle parameter to 84-86° from the longitudinal axis (or 4-6° from perpendicular). This narrow angular range represents the optimal compromise: sufficiently inclined to deflect nail strikes and prevent fracture, yet maintains a large enough effective cutting angle to efficiently remove wood material
Data Source
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AI summary
The present application discloses a flat drill bit (100), wherein the flat drill bit (100) comprises: a stem body (10); a cut flute part (20) provided axially from an end of the stem body (10) and being generally flat-shaped; a threaded guiding part (30) provided axially from an end of the cut flute part (20), wherein the cut flute part (20) includes two longitudinal wings (23) which are configured to be rotationally symmetrical to each other about a longitudinal central axis (O) of the flat drill bit (100), and each longitudinal wing (23) is formed with a cutting edge (21a) at the end of the cut flute part (20) from which the threaded guiding part (30) extends, a rotating trajectory profile caused by the cutting edge (21a) when the flat drill bit (100) rotates is inclined towards the stem body (10) and is at an angle (a) relative to the longitudinal central axis (O), and the angle (a) is in a range between 84° and 86°.