A Novel Soft Sensor for Real-Time Monitoring of the Die Melt Temperature Profile in Polymer Extrusion

Proceedings of the 5th World Congress on Mechanical, Chemical, and Material Engineering

Kelly²,

Wilkinson

2019

Self Cite

Polymers are one of the major classes of raw materials available for many aspects of production. Extrusion is a fundamental method for processing polymeric materials to form a wide range of products. Being poor thermal conductors these materials are difficult to heat and cool and also exhibit high viscosity in their molten state. Hence, heat transfer and rheology are major aspects of polymer processing applications. Also, polymer melts usually exhibit a non-Newtonian behaviour and hence are quite complicated to model. This work aims to observe the thermal behaviour/quality of a number of industrially common polymeric materials under a wide range of processing conditions using a capillary die with a specifically designed thermocouple mesh sensor. The melt temperature is considered as the main parameter in determining the thermal quality of the melt. Materials were processed under different screw speeds and set temperature conditions using three different screw geometries. The results showed that the uniformity of temperature across the melt flow varied considerably with increase in screw rotational speed whilst it was also shown to be dependent upon process settings, screw geometry and material properties. Moreover, it appears that the effects of the material, machine and process settings on the quantity and quality of the process output are heavily coupled with each other and this may cause the process to be difficult to predict and variable in nature. In terms of the flow behaviour, regardless of the processing conditions used, the highest melt temperature was observed always in the middle of the melt flow. At lower processing speeds, the lowest melt temperature was close to the die wall where this position shifted a few millimetres away from the die at higher speeds by forming low temperature shoulder regions (making the melt flow highly thermally inhomogeneous). Moreover, a discussion was made on the possible effects of materials' properties on viscous heat generation during processing. Additionally, the importance of the use of the appropriate thermal monitoring techniques can also be highlighted in determining the actual melt thermal quality during polymer processing applications.

Section: Effects Of Screw Geometrysupporting

confidence: 91%

Investigation of Thermal Stability of Non-Newtonian Melt Flows

Proceedings of the 5th World Congress on Mechanical, Chemical, and Material Engineering

Kelly²,

Wilkinson

2019

Self Cite

“…Therefore, it is clear that process thermal monitoring in polymer extrusion is still having poor performance and hence process control techniques are also experiencing lack of performance. Here, a novel die melt temperature profile prediction soft sensor which was originally proposed by the author will provide a promising solution [87,88].…”

Section: A New Approach For Extrusion Controlmentioning

confidence: 99%

“…Therefore, it is important to use high accuracy and reliable sensor which can provide a wide range of information about the actual melt quality with a fast response time to obtain the feedback, and this would help to achieve the optimum performance from the controller. The soft sensor originally proposed by the author to predict a temperature profile across the extruder die melt flow [87,88] should be useful in obtaining a detailed and an accurate feedback, and hence to apply with a process control strategy.…”

Section: Model-based Extrusion Control With Fuzzy Logicmentioning

confidence: 99%

Single screw extrusion control: A comprehensive review and directions for improvements

Control Engineering Practice

2016

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Polymer extrusion is usually a complex process, particularly due to the coupled nature of process parameters, and hence highly prone to fluctuations. Although a number of different approaches have been attempted in research/industry over the last few decades for extrusion control, it is still experiencing some problems in achieving consistent product quality. Presently, most of the polymer processing extruders are equipped with PID controllers mainly for the control of the screw speed and barrel temperatures in their set limits. It seems that only both of these controllers are commonly used as the major aids of process control to achieve the required melt quality. Although, the quality of the melt output (i.e., a thermally homogeneous melt output which is constant in quantity and quality over the time) is the key variable in polymer extrusion, only a few control techniques are available which make control decisions by observing the actual melt flow quality. Therefore, the development of new control strategies which consider the actual melt quality, perhaps incorporating industrially popular nonlinear techniques such as artificial intelligence, should be highly valuable. In this work, a critical evaluation is made on the state-of-the-art of the previous control approaches in polymer extrusion in industry and research while identifying their limitations. Then, some of the possible directions for future research and also to develop an advanced process control strategy are presented by eliminating a few of the existing limitations.

“…The significance of each selected model term was reviewed and compared with those remaining in the candidate term pool and all insignificant terms were replaced, leading to improved performance without increasing the model size. The authors have used the same technique for the modelling of the die melt temperature profile [29]- [32], melt pressure [33] and motor power consumption [26] in polymer extrusion, and good results have been achieved.…”

Section: B Empirical Modelling Of Extruder Total Energy Consumptionmentioning

confidence: 99%

Monitoring and modelling of the energy consumption in polymer extrusion

2014 European Control Conference (ECC)

Kelly

Vera-Sorroche

et al. 2014

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Extrusion is one of the fundamental methods in polymer processing and is involved in the production of various commodities in diverse industrial sectors. Being an energy intensive production method, process energy efficiency is one of the major concerns and the selection of the most energy efficient processing conditions is a key to reduce operating expenses. Usually, extruders consume energy through the drive motor, barrel heaters, cooling fans, cooling water pumps, gear pumps, etc. Typically the drive motor is the dominant energy consuming device in a polymer processing extruder while barrel/die heaters are responsible for the second largest energy demand. This study was focused on investigating the total energy demand of an extrusion plant while identifying ways to optimise the energy consumption. Total energy consumption of a single screw extruder was measured over different processing conditions and then modelled as a function of a number of major process variables. The results show that the extruder energy demand is heavily coupled with machine, material and process parameters. Also, the proposed models show excellent agreement with the experimental measurements and hence these should be useful in optimising process energy efficiency.