Magnetic Drill Press Holding Force Detection for Secure Attachment

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Solution Overview

Problem

Portable magnetic drill presses face reduced holding force due to surface characteristics like rust, metal shavings, and dust on workpieces, which can affect the magnetic latch's ability to securely attach the drill press.

Innovation Solution

Incorporating a holding force detection assembly with a Hall-effect sensor and a magnetically latched base that measures the magnetic field strength to ensure a secure attachment, preventing the drill from activating if the holding force is insufficient, and deactivating it if the force drops below a threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If magnetic drill press uses magnets to magnetically latch to workpiece, then attachment capability is improved, but surface characteristics like rust and dust reduce holding force

Engineering Contradiction:
Improveholding forceVSAvoidattachment reliability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The drill press detects the holding force before drilling operation begins and prevents motor activation if holding force is insufficient. This preliminary detection and prevention mechanism ensures that drilling only occurs when proper attachment is confirmed, addressing the reliability issue caused by surface contaminants

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the holding force during operation and can deactivate the motor if holding force drops below threshold. This feedback mechanism maintains attachment reliability by responding to changes in magnetic latch strength caused by surface characteristics

Inventive Principle:
Principle #23Feedback

2Measurement precision

If holding force detection assembly is added to measure magnetic field, then attachment monitoring is improved, but device complexity increases

Engineering Contradiction:
Improveholding force measurementVSAvoiddetection assembly complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical holding force measurement mechanisms with a magnetic field sensing approach. The sensor detects changes in magnetic field strength, which correlate to holding force, thereby achieving precise measurement while avoiding complex mechanical linkages and force transmission mechanisms

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

Solution Approach 2:

The magnetic field acts as an intermediary between the magnet and the sensor. Instead of directly measuring mechanical holding force, the sensor detects magnetic field strength, which serves as a proxy indicator. This intermediary approach simplifies the measurement system while maintaining measurement precision

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Ensures reliable and secure drilling by accurately measuring and maintaining the magnetic holding force, preventing accidents and improving drilling precision by ensuring a stable attachment to the workpiece.

Implementation Method 1

The base includes a magnet to create a magnetic field for magnetically latching the base to a workpiece

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

Magnetic drill presses use magnets (i.e., permanent magnets or electromagnets) to magnetically latch the drill press to the workpiece

Methodology Applied
Scientific EffectMagnetism: Magnetism

Implementation Method 3

a sensor coupled to the plug to detect the magnetic field within the base

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP3411173B1Holding force detection for magnetic drill press
Publication Date: 2022.11.16 MILWAUKEE ELECTRIC TOOL CORP
  • EP3411173B1 patent drawingFigure 1
  • EP3411173B1 patent drawingFigure 2~3
  • EP3411173B1 patent drawingFigure 4

AI summary

A drill press includes a main housing, a base coupled to the main housing, and a drill unit supported by the main housing for relative movement therewith. The base includes a bore formed in a top surface and a magnet to create a magnetic field for magnetically latching the base to a workpiece. The drill press further includes a holding force detection assembly having a plug and a sensor coupled to the plug to detect the magnetic field within the base. The holding force detection assembly is received within the bore formed in the top surface of the base.