Exchangeable Drill Bit Cutting Portion With Magnetic Pin Locking

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Solution Overview

Problem

Existing drill bits with combined plug and solder connections require a heat source and soldering device for quick replacement of cutting sections, making on-site replacements impractical and increasing material costs due to the need for a certain height of the cutting section to prevent heat-affected zones.

Innovation Solution

The drill bit employs magnetic pin connections, where pin elements act as permanent magnets, allowing for easy and quick exchange of cutting sections without the need for precise alignment or destructive disassembly, using plug and pin connections that secure the cutting and drill shaft sections against twisting and displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If combined plug and solder connection is used to connect cutting section and drill shaft section, then connection strength is improved, but replacement complexity increases due to requirement of heat source and soldering device

Engineering Contradiction:
Improveconnection strengthVSAvoidreplacement complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The connection system is segmented into modular components: an outer connecting element with receiving bores and an inner connecting element with pin connections. This segmentation allows the cutting section to be replaced by simply removing pins rather than applying heat, reducing replacement complexity while maintaining connection strength through the modular design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The soldering process (thermal/mechanical system requiring heat source) is replaced with a purely mechanical pin connection system. The pin elements engage with receiving bores through simple insertion and extraction actions, eliminating the need for heat sources and soldering devices while maintaining secure connection

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If cutting section height is increased to prevent heat-affected zones during soldering, then connection reliability is improved, but material cost increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidmaterial cost
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The mechanical pin connection system eliminates the need for thermal processes entirely, removing the requirement for a minimum cutting section height to protect against heat-affected zones. This allows optimization of cutting section dimensions based purely on functional requirements rather than thermal protection needs, reducing material waste

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The connection method parameters are changed from thermal (soldering temperature, heat exposure time) to mechanical (pin insertion force, engagement depth). This parameter change allows the cutting section to be designed with minimal height required for pin engagement rather than for thermal protection, reducing material consumption

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If pin connections are used to connect cutting section and drill shaft section, then replacement ease is improved, but alignment precision requirement increases

Engineering Contradiction:
Improvereplacement easeVSAvoidalignment precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The outer connecting element features asymmetric design with receiving bores positioned at specific locations and orientations. This asymmetric geometry provides built-in alignment guidance that ensures proper orientation during pin insertion, reducing the precision required for manual alignment while maintaining secure connection

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The pin connection system incorporates self-aligning features where the receiving bores and pin geometries guide the connection elements into proper alignment automatically during insertion. This self-service alignment mechanism reduces the skill and precision required for replacement operations while ensuring accurate positioning

Inventive Principle:
Principle #25Self-service

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

This design reduces equipment outlay and minimizes the risk of damaging connections during replacement, enabling quick and efficient exchange of cutting sections, while maintaining secure alignment and preventing material wastage by eliminating the need for precise alignment and heat-based soldering.

Implementation Method 1

The pin connections are designed as magnetic pin connections, with the pin element or one of the connecting elements being designed as a permanent magnet

Methodology Applied
Scientific EffectMagnetism: Magnetism

Data Source

PatentEP2794157B1Drill bit with an exchangeable cutting portion
Publication Date: 2023.08.30 HILTI AG
  • EP2794157B1 patent drawingFigure 1
  • EP2794157B1 patent drawingFigure 2
  • EP2794157B1 patent drawingFigure 3A~3C

AI summary

Drill bit (10), which is rotatable about a drilling axis (23), having a drill shaft portion (12) with a first plug-in connecting element, a cutting portion (11) with a second plug-in connecting element, which forms a plug-in connection with the first plug-in connecting element, wherein the cutting portion (11) has a number of sub-cutting portions (16.1-16.4) in each case with a sub-ring portion (18.1-18.4) and at least one cutting segment (19.1-19.4), wherein each sub-ring portion (18.1-18.4) forms a plug-in connection with the first plug-in connecting element and can be connected to the first plug-in connecting element by means of a pin connection.