Conveyor Belt Electromagnetic Sensor Contamination Analysis

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Solution Overview

Problem

Metallic contaminants stuck in the conveyor belt of metal sorting devices cause damage and false detections, leading to impurities in the sorting results, as existing solutions either fail to detect small metallic objects or increase the risk of blowing non-metallic objects due to elevated activation thresholds.

Innovation Solution

The method involves scanning both the objects and the conveyor belt using an electromagnetic sensor to generate belt properties data, which accounts for stuck contaminants, allowing for accurate classification and sorting by adjusting the activation thresholds based on the conveyor belt's electromagnetic properties, thereby improving detection quality and reducing contamination influence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the activation threshold for air nozzles is increased to avoid false detections from contaminants, then false detections are reduced, but small metallic objects become undetectable

Engineering Contradiction:
Improvesorting accuracyVSAvoiddetection sensitivity
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the detection signal into two components: belt background signal and object signal. By separately identifying and subtracting the belt's electromagnetic properties (contaminants included) from the total scanned signal, the system can use a lower activation threshold without false detections from contaminants, thereby maintaining both reliability and measurement precision

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the belt properties data representing electromagnetic properties of contaminants stuck in the conveyor belt and removes this background interference from the detection process. This extraction allows the system to detect small metallic objects with high sensitivity while ignoring the harmful background signal from contaminants

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If the activation threshold is increased to account for contaminants, then false detections are reduced, but detection quality deteriorates

Engineering Contradiction:
Improvesorting accuracyVSAvoiddetection quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary scanning to generate belt properties data before using the threshold for actual object detection. By pre-characterizing the electromagnetic properties of contaminants in the belt and storing this as background data, the system establishes an accurate baseline that enables both high reliability and high detection quality during subsequent sorting operations

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the scanned electromagnetic properties of the belt are continuously monitored and used to adjust the detection threshold. The system compares the total scanned signal with the stored belt properties data, and only activates air nozzles when the difference exceeds the threshold, thereby maintaining high detection quality while ensuring reliability

Inventive Principle:
Principle #23Feedback

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 approach enhances the accuracy of sorting by considering the conveyor belt's electromagnetic properties, reducing damage and false detections, and maintaining the ability to detect small metallic objects while minimizing the impact of stuck contaminants.

Implementation Method 1

scanning the electromagnetic properties of the objects and the conveyer belt by an electromagnetic sensor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2698214B1Method and apparatus for analyzing metal objects considering changing belt properties
Publication Date: 2015.01.21 TOMRA SORTING AS
  • EP2698214B1 patent drawingFigure 1~2
  • EP2698214B1 patent drawingFigure 3a~3c
  • EP2698214B1 patent drawingFigure 4a~4e

AI summary

The invention relates to a method for analyzing objects (3) depending on their electromagnetic properties, such as for analyzing and sorting them into non-metallic and metallic objects. The method comprising the steps of conveying (S13) the objects (3) to be analyzed on a conveyer belt (1); scanning (S 14) the electromagnetic properties of the objects (3) and the conveyer belt (1) by an electromagnetic sensor (9), wherein the electromagnetic properties of the conveyer belt (1) are dependent on metallic contaminants (19) which are stuck in the conveyer belt (1); generating belt properties data representing the electromagnetic properties of the conveyer belt (1), and analyzing the objects (3) according to the scanned electromagnetic properties and the belt properties data. This has the benefits that the electromagnetic properties of the conveyer belt (1), namely the influence of metallic contaminants (19) which are stuck in the conveyer belt (1), are considered when distinguishing between metallic and non-metallic objects which have to be sorted. This way, the objects (3) which got stuck in the conveyer belt (1) over time, may influence a sorting less, which may improve sorting results. Further, the invention relates to an apparatus for executing such a method.