Thermoplastic Shrinkage Measurement Using Optical Tracking

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Solution Overview

Problem

Current methods for determining the shrinkage characteristics of thermoplastic materials are complex, costly, and insufficiently precise, particularly in predicting behavior under dynamic temperature changes, leading to suboptimal shrink processes and potential material failure.

Innovation Solution

A method and device that involve heating a test piece of defined dimensions above its shrinkage temperature, using infrared sensors to monitor dimensional changes, and optionally connecting it to dimensionally stable materials to simulate real-world conditions, allowing for precise measurement of longitudinal and transverse shrinkage while maintaining or varying temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional tensile test methods are used to determine material properties, then mechanical properties can be detected, but the device dimensions are large, acquisition costs are high, and multiple tests are required resulting in time consumption

Engineering Contradiction:
Improvematerial property detection accuracyVSAvoiddevice dimensions and structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a simplified model system that copies the essential shrinkage behavior of thermoplastic materials without requiring full-scale industrial equipment. By using a small test piece with embedded markers and optical tracking, the invention replicates the key physical phenomenon (thermal shrinkage) in a compact, cost-effective manner that eliminates the need for large tensile testing machines while maintaining measurement accuracy.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The invention replaces complex mechanical measurement systems with optical detection methods. Instead of using mechanical extensometers or large-dimensional testing equipment, the patent uses optical markers tracked by cameras or optical sensors to measure dimensional changes. This substitution dramatically reduces device complexity and cost while improving measurement precision for thermal shrinkage characteristics.

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

2Measurement precision

If conventional tensile test methods are used to determine material properties, then mechanical properties can be detected, but multiple tests must be carried out resulting in time consumption

Engineering Contradiction:
Improvematerial property detection accuracyVSAvoidtesting duration
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent merges multiple measurement capabilities into a single integrated test setup. By combining optical marker tracking, temperature control, and dimensional measurement in one system, the invention can simultaneously capture longitudinal and transverse shrinkage behavior during a single heating cycle. This eliminates the need for multiple separate tensile tests that would be required by conventional methods, dramatically reducing testing time while maintaining comprehensive material characterization.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If material characteristics are not known or insufficiently known, then shrinkage processes cannot be optimized, but articles may have unstable storage, material tearing, or material flow during shrinkage

Engineering Contradiction:
Improvestorage stability and shrinkage process reliabilityVSAvoidmaterial characteristics knowledge
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent systematically varies and measures multiple material parameters including longitudinal shrinkage, transverse shrinkage, and their interaction during controlled heating. By capturing how these parameters change with temperature and time, the invention provides comprehensive material characteristics data that enables reliable optimization of shrinkage processes. This detailed parameter knowledge prevents storage instability, tearing, and material flow issues by allowing precise process parameter selection based on measured material behavior.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If precise determination of material characteristics is performed using conventional methods, then complete material behavior can be assessed, but the process is complex and requires multiple tests

Engineering Contradiction:
Improvecomplete material behavior assessmentVSAvoidtesting process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent adds the dimension of optical tracking to traditional shrinkage measurement. By embedding markers in the test piece and tracking their positions optically in multiple directions, the invention simultaneously captures two-dimensional shrinkage behavior (longitudinal and transverse) during a single test. This dimensional approach to measurement provides complete material behavior assessment without requiring multiple separate tests or complex mechanical measurement systems.

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

Enables precise and efficient determination of thermoplastic material behavior during shrinkage, improving the accuracy of shrink processes and reducing material instability and aesthetic issues like folding.

Implementation Method 1

If the respective shrink film is exposed to heat from the radiant heaters, it may initially expand by a small amount up to its crystalline melting point

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

only to then shrink to a certain value

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

using infrared sensors to monitor dimensional changes

Methodology Applied
Scientific EffectInfrared radiation detection: Infrared Radiation

Data Source

PatentEP3114465B1Method and device for ascertaining shrinkage characteristics of a flat material strip made of a thermoplastic material
Publication Date: 2018.03.28 KRONES AG
  • EP3114465B1 patent drawingFigure 1A~1B
  • EP3114465B1 patent drawingFigure 2
  • EP3114465B1 patent drawingFigure 3

AI summary

The invention relates to a method and a device for ascertaining shrinkage characteristics of a flat material strip made of a thermoplastic material. As part of the method, a piece of sample (5) with defined measurements undergoes a heating process to a temperature above a shrinkage temperature which is effective for the respective material of the piece of sample (5). After the heating process, a dimensional change of the piece of sample (5) is monitored and/or measured in the ongoing shrinkage process over the time curve, and a relationship to the duration of the shrinking process and to the respective temperature and/or the temperature change of the piece of sample (5) during the shrinkage process is generated.