Variable-Diameter Tungsten Carbide Burr for Jam-Resistant Lock Drilling

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Solution Overview

Problem

Existing drilling tools for cylinder locks, such as tungsten carbide tipped drills and solid tungsten carbide drill bits, are prone to jamming and snapping due to their brittleness and limited flexibility, requiring high pressure and precision, which shortens their lifespan and makes them expensive and difficult to use effectively, especially when encountering hardened pins or anti-drill features.

Innovation Solution

A tungsten carbide burr with a distal end portion of greater diameter than the cylindrical cutting portion provides clearance for debris and accommodates minor alignment changes, featuring fine teeth for efficient cutting and reduced jamming, allowing for high-speed operation and increased maneuverability, enabling drilling with less precision and greater speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a tungsten carbide tipped drill or solid tungsten carbide drill bit is used to drill cylinder locks, then the tool can cut through hardened pins and anti-drill features, but the tool is prone to jamming and snapping due to brittleness and limited flexibility

Engineering Contradiction:
Improvecutting abilityVSAvoidjamming and snapping resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The drill bit is divided into multiple sections with different diameters along its length. The distal end has a larger diameter for initial cutting and debris clearance, while the proximal end has a smaller diameter for flexibility and maneuverability. This segmentation allows each section to perform its specific function optimally, reducing overall brittleness while maintaining cutting ability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drill bit incorporates a flexible shaft portion that allows dynamic movement and bending during operation. This flexibility enables the tool to accommodate misalignments and reduce stress concentrations that would otherwise cause snapping in rigid tungsten carbide tools.

Inventive Principle:
Principle #15Dynamics

2Productivity

If high pressure is applied to make the drill bit cut through hardened pins, then cutting effectiveness is improved, but the likelihood of the tool snapping increases

Engineering Contradiction:
Improvecutting effectivenessVSAvoidsnap resistance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The graduated diameter sections distribute cutting forces along the length of the drill bit rather than concentrating them at a single point. The larger distal end handles initial breakthrough and debris removal, while smaller proximal sections provide flexibility, reducing stress and snap risk during high-pressure cutting operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The drill bit's diameter parameter varies along its length, creating a gradient structure that optimizes the balance between cutting force application and structural flexibility. This parameter change allows effective cutting under pressure while maintaining sufficient flexibility to prevent snapping.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If precision and alignment are maintained to prevent tool snapping, then tool lifespan is extended, but the drilling process becomes more difficult and time-consuming

Engineering Contradiction:
Improvetool lifespanVSAvoiddrilling difficulty
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The larger diameter distal end portion acts as a cushion or buffer zone that accommodates minor misalignments and debris accumulation before they can cause the tool to snap. This beforehand cushioning protects the tool during operation, extending its lifespan without requiring perfect alignment from the operator.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The varying diameter parameter along the drill bit's length provides built-in tolerance for alignment variations. The gradient from larger to smaller diameter sections allows the tool to self-correct minor misalignments, making operation easier while maintaining reliability.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If a smaller diameter drill bit is used for maneuverability, then ease of operation is improved, but debris clearance becomes problematic leading to jamming

Engineering Contradiction:
ImprovemaneuverabilityVSAvoidjamming resistance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The drill bit is segmented into a larger diameter distal end for debris clearance and a smaller diameter proximal end for maneuverability. This segmentation allows each section to optimize its function: the larger end creates space for chip evacuation while the smaller end provides flexibility and ease of handling.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution addresses the two-dimensional conflict between diameter size by introducing a third dimension - the longitudinal variation in diameter along the tool's length. This dimensional change allows the tool to have different effective diameters at different positions, simultaneously achieving maneuverability and debris clearance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 burr design significantly reduces the likelihood of jamming and snapping, allowing for faster and more efficient drilling of cylinder locks, including those with anti-drill features, and enables the creation of slots to eject pins without drilling through them, making the process more accessible to less experienced personnel.

Implementation Method 1

A tungsten carbide burr, having a cutting portion which comprises a distal end portion 21 having a diameter greater than a diameter of a cylindrical cutting portion 20

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP3791981B1Burr and method
Publication Date: 2023.07.26 SOUBER TOOLS LTD
  • EP3791981B1 patent drawingFigure 1~2
  • EP3791981B1 patent drawingFigure 3~5
  • EP3791981B1 patent drawingFigure 6~7

AI summary

The present invention provides a burr 13 in the form of a generally cylindrical rod, the burr 13 having a proximal end 14 for mounting in a tool for rotating the burr and a distal cutting end 15, the burr having a cutting portion 17a, 17b defined by a portion of a surface of the burr which comprises a plurality of teeth 16, the cutting portion 17a, 17b including and extending from the distal end 15 back towards the proximal end 14, the burr being characterised in the cutting portion 17a, 17b comprising a cylindrical portion 17b of a first diameter and a distal end portion 17a having a second diameter greater than the first diameter. The burr 13 is particularly suited to the drilling of cylinder locks.