Terahertz Extrusion Measurement Transit Time Correction
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Solution Overview
Problem
Existing methods for measuring the dimensional properties of elongated and flat industrial products, such as tubing, cables, and sheets, suffer from inaccuracies due to mechanical wear, defocusing, and health hazards associated with contact and optical methods, while non-contact methods like terahertz radiation face challenges in maintaining accuracy during product movement and vibration.
Innovation Solution
A non-contact measurement system using terahertz radiation that produces a curtain of parallel rays to scan products, with a processor that computes and corrects transit time variations to ensure accurate dimensional parameter determination, thereby improving measurement accuracy across the entire product surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If contact methods (rollers or wheels) are used to measure flat product thickness, then mechanical simplicity is achieved, but measurement accuracy deteriorates due to mechanical wear and wheel bounce
Solution Approach 1:
The patent replaces the mechanical contact measurement system (rollers or wheels) with an optical measurement system using laser distance measuring devices. This substitution eliminates mechanical wear and bounce issues while achieving non-contact measurement, directly resolving the contradiction between mechanical simplicity and measurement accuracy.
2Ease of operation
If optical distance measuring devices are used to measure flat product thickness, then non-contact measurement is achieved, but measurement accuracy deteriorates due to defocussing on product vibration or thickness change
Solution Approach 1:
The patent implements dynamic focusing capability in the optical measurement system, allowing the focal point to adjust automatically in response to product vibration or thickness changes. This dynamic adaptation maintains measurement accuracy despite product movement, resolving the contradiction between non-contact operation and measurement precision.
3Measurement precision
If contact or optical methods are used to measure flat products, then local thickness measurement is achieved, but measurement coverage deteriorates as only a narrow part of the product width is measured
Solution Approach 1:
The patent employs multiple optical measuring devices arranged in arrays across the product width, dividing the measurement task into multiple parallel measurement zones. This segmentation approach enables simultaneous measurement across the entire product surface while maintaining the precision of individual local measurements, resolving the contradiction between local accuracy and overall coverage.
4Ease of operation
If radioactive beta or x-rays are used to measure wall thickness without contact, then non-contact measurement is achieved, but health hazards increase requiring special handling
Solution Approach 1:
The patent replaces dangerous radioactive sources with safe optical laser devices that have no long-term health hazards. The optical system achieves the same non-contact measurement function without requiring special handling or safety protocols, eliminating the harmful effects while maintaining measurement capability.
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
The system achieves high accuracy in measuring dimensional parameters, with an improvement of 1 micron in precision, suitable for applications in fine wires, optical fibers, and high-tolerance cable manufacturing, and effectively addresses the limitations of previous methods by maintaining accuracy during product movement and vibration.
Implementation Method 1
Terahertz radiation (THz) has the advantage in that it behaves in a manner similar to that of white light, that is to say that the radiation can be reflected by mirrored surfaces but is able to penetrate and pass through dielectric or insulating materials such as rubber, paper and various plastics including polyethylene and the like.
Implementation Method 2
The speed of transmission of THz radiation through the dielectric or insulating material is dependent on the chemical composition and material density of the product
Implementation Method 3
The system disclosed herein utilises an optical system to produce a curtain of THz radiation through which the product passes in a linear fashion in its path of travel.
Implementation Method 4
The transient time or speed of each successive ray in the curtain of rays is used to compute, by matrix imaging methods, the dimensional parameters of the product
Data Source
AI summary
The invention relates to apparatus for monitoring an extruded product moving in an inline extrusion process so as to effect quality control of the process by continuously measuring dimensional parameters and determining the existence of contaminants in the extrusion. The apparatus makes use of Terahertz radiation which is adapted to provide a curtain of parallel rays of the radiation which is scanned across the product as the product passes therethrough in a linear manner. The composition of the emitted radiation received after the scanning process is subject to an imaging analysis to determine the dimensional parameters of the moving products. The imaging analysis involves applying correction values to the measured transit times of the rays crossing the products which depends on its position within the curtain of rays thereby to remove inaccuracies in the final measurement results.