Spiral Welded Drill Shaft for Drilling Stability and Friction Reduction
Solution Overview
Problem
Wet drill bits lack stability and guidance during drilling, leading to undesired movements and geometry deviations in drilled holes, and suffer from high friction due to large contact surfaces, which reduces drilling progress and service life.
Innovation Solution
A drill bit with a tubular drill shaft designed as a welded spiral tube, featuring helical connecting weld seams that increase rigidity and reduce friction by acting as a stiffening element and conveyor helix for cooling and flushing liquids, allowing for improved guidance and liquid transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the drill shaft is designed as a conventional tubular structure, then the manufacturing is simple, but the stiffness and guidance stability during drilling are insufficient
Solution Approach 1:
The drill shaft is designed with a spiral curvature instead of a straight tubular structure. This spiral geometry inherently increases the stiffness and moment of inertia of the shaft, improving its resistance to bending and torsional forces during drilling operations without requiring additional complex reinforcement elements.
Solution Approach 2:
A guide element is introduced as an intermediary component that works in conjunction with the spiral drill shaft. This guide element interacts with the workpiece surface to provide additional guidance and stability, allowing the shaft to maintain its spiral configuration while achieving the required guidance precision.
2Stability of the object's composition
If the drill shaft has a large contact area with the core and borehole, then guidance is improved, but friction increases reducing drilling progress and service life
Solution Approach 1:
The spiral configuration of the drill shaft creates a more efficient contact pattern with the core and borehole. Instead of a continuous large-area contact, the spiral geometry provides periodic point or line contacts that maintain guidance stability while significantly reducing the total contact area and associated friction forces.
Solution Approach 2:
The continuous contact surface is segmented into discrete contact points along the spiral path. This segmentation reduces the cumulative friction effect while maintaining guidance through the periodic engagement of different sections of the spiral shaft with the workpiece.
3Stability of the object's composition
If the drill shaft has a large contact area with the core and borehole, then guidance is improved, but the service life of the drill shaft is reduced
Solution Approach 1:
The spiral curvature distributes the mechanical stresses and wear across different sections of the drill shaft over time. As the shaft rotates, different portions of the spiral geometry engage with the workpiece, preventing concentrated wear at any single location and thereby extending the overall service life.
Solution Approach 2:
The wear and stress effects are segmented across multiple contact points along the spiral path rather than concentrated on a single large contact area. This segmentation allows the drill shaft to withstand prolonged use as wear is distributed and can be managed across different sections.
4Weight of moving object
If conventional tubular material is used for the drill shaft, then the manufacturing is straightforward, but the weight cannot be reduced
Solution Approach 1:
The spiral configuration allows the use of thinner-walled tubular material to achieve the required stiffness and strength. The geometric advantage of the spiral shape provides structural reinforcement that compensates for the reduced wall thickness, enabling weight reduction while maintaining performance.
Solution Approach 2:
The design transitions from a straight tubular configuration to a spiral configuration, changing the geometric parameters of the shaft. This parameter change allows optimization of the weight-to-stiffness ratio by utilizing the inherent structural advantages of spiral geometry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The spiral tube design enhances the stability and guidance of the drill shaft, reduces friction, and increases drilling efficiency and service life by minimizing contact surfaces and optimizing liquid transport.
Implementation Method 1
a helical connecting weld seam, which acts as a stiffening element for the drill shaft and increases the stiffness of the drill shaft
Implementation Method 2
reduces friction by acting as a stiffening element and conveyor helix
Implementation Method 3
conveyor helix for cooling and flushing liquids
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
The invention relates to a core bit (10) for producing a drilled hole (24) with a drilled-hole diameter (d2) and a drill core (23) having a core diameter (d1) in a workpiece (22), having a cutting portion (11) with one or more cutting segments (15), a drill-shank portion (12) with a tubular drill shank (16) and a connecting device (13) which connects the cutting portion (11) and the drill-shank portion (12) releasably or non-releasably together, wherein the tubular drill shank (16) is configured as a welded spiral tube.