Twin-Screw Extrusion Modelling

2006 ◽  
Vol 45 ◽  
pp. 436-441 ◽  
Author(s):  
P.A. McGuire ◽  
S. Blackburn ◽  
E.M. Holt
Keyword(s):  
Temperature Correction ◽  
Force Balance ◽  
Rheological Parameters ◽  
Twin Screw Extruder ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Single Screw Extrusion ◽  
Heating Effects ◽  
Screw Extrusion ◽  
Twin Screw

A mathematical model has been derived to describe the pressure drop along the conveying and reverse sections of a partly full, fully intermeshing co-rotating twin-screw extruder. The model extends previous work on single screw extrusion, whereby the Benbow-Bridgwater model of paste rheology is combined with a force balance on a plug of paste. Experiments to verify the model have been carried out using a laboratory scale twin-screw extruder fitted with a hydraulic feeder and a modified barrel section allowing the collection of pressure data at numerous points along the extruder. Initial results suggested that the model was able to correctly predict the trends observed but underestimated the absolute values of the pressure. This was attributed to a change in the rheology of the paste due to viscous heating effects. Further experimental work was carried out to determine the relationship between the rheological parameters and temperature; this allowed a temperature correction to be made to the initial data after which the agreement with the predictions was greatly improved.

Effect of Wall Conditions on PVC-R Co-Rotating Conical Twin-Screw Extrusion

2011 ◽  
Vol 314-316 ◽  
pp. 419-427
Author(s):  
Ying Han Cao ◽  
Jin Nan Chen
Keyword(s):  
Pressure Difference ◽  
Volumetric Flow Rate ◽  
Wall Slip ◽  
Twin Screw Extruder ◽  
Slip Coefficient ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Good For

The effect of wall conditions on co-rotating conical twin-screw extrusion of rigid polyvinyl chloride (PVC-R) is studied. The relationship between the shear stress at the screw surface and the slip velocity of the flowing melt obeys Navier’s linear law. When the volumetric flow rate is 3.83×10-5 m3/s, the pressure difference between the entrance and exit of the metering section of co-rotating conical twin-screw extruder is calculated under different wall conditions by using the evolution technique in POLYFLOW. The 3D isothermal flow fields of PVC-R are also calculated. The results show that when the slip coefficient is smaller than 104 , the pressure difference is constant, corresponding to the full slip condition. When the slip coefficient is larger than 104 , with the slip coefficient decreasing, the pressure difference, and the gradients of velocity, pressure and shear rate decrease. The residual stress of the product is thus reduced. Therefore, increasing wall slip is good for the stability of polymer extrusion and the product quality. The dispersive and the distributive mixing of the twin-screw extruder under different slip conditions are also studied. Results show that when the slip coefficient is 107 , it is good for the co-rotating conical twin-screw PVC-R mixing extrusion.

scholarly journals Computer modeling for polymer processing co-rotating twin screw extrusion – nonconventional screw configurations

Mechanik ◽  
2017 ◽  
Vol 90 (4) ◽  
pp. 282-287
Author(s):  
Adrian Lewandowski ◽  
Krzysztof Wilczyński
Keyword(s):  
Computer Modeling ◽  
Three Dimensional ◽  
Polymer Processing ◽  
Twin Screw Extruder ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Polymer Flow ◽  
Screw Extrusion ◽  
Twin Screw

Computer modeling of co-rotating twin screw extrusion with the use of nonconventional screw configurations has been presented. The polymer flow in the co-rotating twin screw extruder has been described. Some examples of three-dimensional, non-Newtonian modeling are shown. CFD generally oriented software ANSYS Polyflow has been used for modeling.

scholarly journals Effect of the Intensive Plasticizing Zone Design on the Effectiveness of Corotating Twin-Screw Extrusion

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Emil Sasimowski ◽  
Łukasz Majewski
Keyword(s):  
Experimental Design ◽  
Rotational Speed ◽  
Extrusion Process ◽  
Empirical Models ◽  
Filling Ratio ◽  
Mixing Zone ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Screw Extrusion ◽  
Twin Screw

The aim of this study was to investigate the effect of a new intensive plasticizing and mixing screw zone design on the effectiveness of the corotating twin-screw extrusion process for talc-filled polypropylene. The study determined the effect of the angle between the trilobe kneading elements forming the intensive plasticizing and mixing zone of the screws, the screw rotational speed, and the polypropylene/talc filling ratio on the characteristics of the extrusion process in a corotating twin-screw extruder EHP-2x20. The paper describes the experimental design and obtained results as well as the developed empirical models for selected variables of the extrusion process.

scholarly journals Use of response surface methodology (RSM) for composite blends of low grade broken rice fractions and full-fat soybean flour by a twin-screw extrusion cooking process

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Nahemiah Danbaba ◽  
Iro Nkama ◽  
Mamudu Halidu Badau
Keyword(s):  
Response Surface Methodology ◽  
Bulk Density ◽  
Response Surface ◽  
Extrusion Cooking ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Broken Rice ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Feed Moisture

In this study, seventeen (17) composite blends of broken rice fractions and full-fat soybean, formulated using response surface methodology and central composite design within a range of barrel temperatures (100-140 °C), initial feed moisture content (15-25%) and soybean composition (8-24%), were extruded with a twin-screw extruder and the expansion and color indices were optimized. The results indicated a significant (p<0.05) effect of extrusion conditions on the responses. Fitted predictive models had coefficients of 88.9%, 95.7%, 97.3%, 95.4% and 95.2%, respectively, for expansion index, bulk density, lightness, redness and yellowness. The p-value and lack-of-fit tests of the models could well explain the observed variability and therefore could be used to establish production setting for the twin-screw extruder. The optimum extrusion conditions were found to be 130 °C (barrel temperature), 20% (feed moisture level) and 23% feed soybean composition and optimum responses in terms of bulk density, expansion index, lightness, redness and yellowness chroma indices were 0.21 g cm-3, 128.9%, 17.1, 3.13 and 24.5 respectively. This indicates that optimum conditions can be established in twin-screw extrusion cooking of broken rice fractions and full-fat soybean composite blends that can result in product of low bulk and maximum expansion with a satisfactory light yellow product color that can be used to produce products that valorize broken rice and reduce qualitative postharvest loss.

Numerical Simulation of Effect of Slip Conditions on PVC Co-Rotating Twin-Screw Extrusion

2011 ◽  
Vol 189-193 ◽  
pp. 1946-1954 ◽  
Author(s):  
Ying Han Cao ◽  
Jin Nan Chen
Keyword(s):  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Wall Slip ◽  
Slip Condition ◽  
Twin Screw Extruder ◽  
Slip Coefficient ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Slip Conditions ◽  
Twin Screw

The effect of wall conditions on the co-rotating parallel twin-screw extrusion of rigid polyvinyl chloride (RPVC) is studied. The relationship between the shear stress at the screw wall and the slip velocity of the flowing melt obeys Navier’s linear law. At zero pressure difference between the entrance and exit of the melting section of twin-screw extruder, the volumetric flow rate and 3D isothermal flow fields of RPVC are calculated under different wall slip conditions in the metering section of the twin-screw extruder by using the evolution technique in POLYFLOW. The results show that when the slip coefficient is smaller than 104Pa*s/m , the volumetric flow rate of the melt is constant, corresponding to the full slip condition. When the slip coefficient is larger than 104Pa*s/m , with the slip coefficient decreasing, the volumetric flow rate and viscosity increase, but the gradients of velocity, pressure, and shear rate decrease. The residual stress of the product is thus reduced. Therefore, increasing wall slip is good for the stability of polymer extrusion and the product quality. The dispersive and the distributive mixing of the twin-screw extruder under full slip and no slip conditions are also studied. Results show that the mixing performance under no-slip condition is better than under full-slip condition, but slip at the wall is good for the extrusion of heat-sensitive materials.

Twin screw extrusion with Expancel foaming agent

2013 ◽  
Vol 33 (6) ◽  
pp. 501-508 ◽  
Author(s):  
Janusz W. Sikora ◽  
Volodymir Levytskyi ◽  
Volodymir Moravskyi ◽  
Hendrik Gerlach
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Foaming Agent ◽  
Foam Extrusion ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Screw Diameter

Abstract Foam extrusion of polypropylene with a foaming agent, Expancel 950 MB 80 and 950 MB 120, was performed. The process was performed using a co-rotating twin screw extruder, with an 18 mm screw diameter and 24 L/D ratio. Dependences of polymer mass flow rate, extrudate foam rate, and polymer pressure on screw speed and foaming agent amount were determined and relevant conclusions were drawn.

scholarly journals Influence of the Conditions of Corotating Twin-Screw Extrusion for Talc-Filled Polypropylene on Selected Properties of the Extrudate

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1460 ◽  
Author(s):  
Sasimowski ◽  
Majewski ◽  
Grochowicz
Keyword(s):  
Maximum Tensile Stress ◽  
Extrusion Process ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
Melt Flow Rate ◽  
Test Segment ◽  
Screw Extrusion ◽  
Twin Screw

The aim of the study was to determine the effect of the application of processing screws with a modified test segment in a corotating twin-screw extruder on selected properties of talc-filled polypropylene extrudate. The test segment was built of trilobe kneading elements and its design modifications refered to changing the distance between the kneading elements and the angle of positions of kneading elements that are relative to each other. The performed tests included the production of extrudate with various degrees of talc-filling using five design solutions of the test segment and then measurements of selected properties, such as tensile strength, elongation at maximum tensile stress, and melt flow rate. Structural studies using scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were also carried out. The study includes not only the description of experimental results but also the determination of empirical models describing the dependence of the properties of the obtained extrudate on the conditions of the extrusion process and the design features of the test segment.

scholarly journals Optimization and Numerical Simulation of Outlet of Twin Screw Extruder

2018 ◽  
Vol 153 ◽  
pp. 05004
Author(s):  
Yuan Zhang ◽  
Xiaohan Jiang ◽  
Huaping Fan ◽  
Xihan Li
Keyword(s):  
Numerical Simulation ◽  
Interpolation Method ◽  
Reverse Flow ◽  
Linear Interpolation ◽  
Mechanical Analysis ◽  
Rheological Parameters ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Twin Screw ◽  
Improved Model

In view of the unreasonable design of non-intermeshing counter-rotating twin screw extruder die, the problem of productivity reduction was discussed. Firstly, the mathematical model of extruder productivity was established. The extruder die model was improved. Secondly, the force analysis of twin screw extruder physical model was carried out. Meanwhile, A combination of mechanical analysis and numerical simulation was adopted. The velocity field, pressure field and viscosity field were calculated by Mini-Element interpolation method, linear interpolation method and Picard iterative convergence method respectively. The influence of die model on the quantity of each field before and after improvement was analyzed. The results show that the improved model had increased the rheological parameters of the flow field, the leakage and reverse flow decreased. Through post-processing calculation, the productivity of the third dies extruder was 10% higher than before. The research results provide a theoretical basis for the design and optimization of die model of non intermeshing counter-rotating twin screw extruder.

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