Tubular Strand Temperature Sensing Without Internal Probe Insertion
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Solution Overview
Problem
Existing methods for measuring the temperature of tubular strands, such as plastic tubes, after extrusion are limited by the need for direct insertion of sensors into the interior, which is cumbersome and often only possible immediately after extrusion, and lack precise measurement of diameter, wall thickness, and temperature for optimizing production parameters.
Innovation Solution
A device and method using contactless temperature sensors to measure the outside temperature of a tubular strand at multiple positions, comparing these measurements to infer the internal temperature through thermal conductivity and thermal capacity, and utilizing iterative finite element methods for precise temperature determination within the strand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contactless temperature sensors are used to measure outside temperature at multiple positions, then measurement accuracy is improved, but device complexity increases due to multiple sensors and evaluation apparatus
Solution Approach 1:
The temperature measurement system is segmented into multiple contactless temperature sensors positioned at different locations along the tubular strand, with each sensor measuring temperature at its specific position. This segmentation allows comprehensive temperature profiling without requiring complex single-point measurement systems, resolving the contradiction by distributing measurement functionality across multiple simple sensors rather than one complex system.
Solution Approach 2:
An evaluation apparatus acts as an intermediary between the multiple temperature sensors and the final temperature determination. This intermediary processes the temperature data from multiple positions, applies thermal conduction models, and calculates the internal temperature of the strand. The evaluation apparatus mediates the complexity by centralizing the computational logic while keeping the physical sensor system simple and distributed.
2Measurement precision
If direct sensor insertion into the interior of the tubular strand is used, then internal temperature measurement is achieved, but ease of operation deteriorates due to cumbersome insertion requirements and limited timing window
Solution Approach 1:
The mechanical system of physically inserting sensors into the strand interior is replaced with a contactless optical measurement system. Temperature sensors measure the external surface temperature optically without mechanical contact, and thermal conduction principles are used to infer internal temperature. This substitution eliminates the cumbersome insertion operation entirely while maintaining internal temperature measurement capability through non-contact means.
Solution Approach 2:
Thermal conduction theory serves as an intermediary between the external temperature measurements and the internal temperature determination. Instead of directly measuring internal temperature through intrusive sensors, the system uses thermal conduction models to translate external surface temperature data into internal temperature information, eliminating the need for physical insertion while maintaining measurement accuracy.
3Loss of information
If multiple temperature measurements at different positions are taken, then temperature distribution information is improved, but measurement time increases
Solution Approach 1:
Multiple temperature sensors are positioned along the strand to continuously measure temperature distribution as the strand passes through the measurement zone. The evaluation apparatus continuously processes temperature data from all sensors simultaneously, providing continuous information about temperature distribution without interrupting the extrusion process. This continuous measurement approach eliminates information loss while minimizing time consumption through parallel measurement.
Solution Approach 2:
Temperature measurements are taken at multiple positions along the strand path in advance, with the evaluation apparatus preparing thermal conduction calculations and temperature distribution models before the actual measurement completes. This preliminary preparation allows rapid processing of temperature data and quick determination of internal temperature, reducing overall measurement time while maintaining comprehensive distribution information.
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 accurate determination of internal temperature without direct sensor insertion, improving measurement accuracy of diameter and wall thickness, and allowing better process control for minimal sagging, energy input, and conveying speed optimization.
Implementation Method 1
a first temperature sensor (30) for measuring a first temperature (T1) of the outside of the tubular strand (12)
Implementation Method 2
the temperature within the tubular strand (12) and/or on the inside of the tubular strand (12) is determined from the comparison of the first and second temperatures
Data Source
AI summary
A device for determining the temperature of a tubular strand conveyed out of an extrusion device includes at least one temperature sensor configured to measure a first temperature of an outside of the tubular strand at a first position of the tubular strand. An evaluation apparatus further included and configured to compare the first temperature with a second temperature of the outside of the tubular strand at a second position of the tubular strand and determine at least one of a temperature within the tubular strand or a temperature on the inside of the tubular strand at a position of the tubular strand based on the comparison of the first and second temperature.