Segmented Drill Bit Inner Profile to Prevent Core Jamming
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Solution Overview
Problem
Segmented drill bits face issues with drill core jamming, particularly during core drilling operations, where fragments can break and get stuck between the drill bit and the core, complicating the removal process, especially for small drill bit diameters.
Innovation Solution
A drill bit design featuring two drilling segments with varying inner distances from the longitudinal axis, where one segment has a strictly monotonic profile with a single absolute minimum value and the other segment has a greater minimum value, reducing contact surfaces and the risk of jamming, and allowing for a mirror-symmetrical design that enhances smoothness and reduces vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If segmented drill bits are used with constant inner distance, then the drilling operation is stable, but the drill core jams between the drill bit and drill core
Solution Approach 1:
The patent applies asymmetry by designing the first drilling segment with a non-circular cross-section where the inner distance from the longitudinal axis varies circumferentially, creating an asymmetric profile with one absolute minimum value. This asymmetric geometry prevents the drill core from jamming by ensuring minimal contact surface area, while the second drilling segment maintains a constant (symmetric) inner distance for stability. The combination resolves the contradiction between drilling stability and jamming prevention.
2Ease of operation
If exchangeable cutting portion is used, then the drill core removal is easier, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the cutting portion into multiple discrete drilling segments (at least two segments) that are spaced apart circumferentially. Each segment is independently fastened to the drilling shaft, allowing the drill core to be removed by simply detaching these segmented components. This segmentation approach enables easier drill core removal compared to a fixed cutting portion, while avoiding the complexity of fully exchangeable cutting portions by maintaining a simpler fastening system.
Data Source
AI summary
Drill bit (20) including a drilling shaft and a cutting portion having a first drilling segment (23-1) and a second drilling segment (23-2). The first drilling segment (23-1) has a first inner lateral surface (28-1) with a first inner distance (B1(φ, h)), and the second drilling segment (23-2) has a second inner lateral surface (28-2) with a second inner distance (B2(φ, h)) from the longitudinal axis (24) of the drilling shaft. The first inner distance (B1(φ, h)) varies between a first maximum value (Bmax,1) and a first minimum value (Bmin,1) over the circumference of the first drilling segment (23-1) and has precisely one first absolute minimum value (Bmin,1). The second inner distance (B2(φ, h)) is greater than or equal to the first absolute minimum value (Bmin,1) over the circumference of the second drilling segment (23-2).