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.

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.

Design of an Innovative Three-Dimensional Print Head Based on Twin-Screw Extrusion

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Joaquim M. Justino Netto ◽  
Zilda de C. Silveira
Keyword(s):  
Mechanical Design ◽  
Three Dimensional ◽  
Polymer Processing ◽  
Twin Screw Extrusion ◽  
Print Head ◽  
Embodiment Design ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Alternative Material ◽  
3D Printers

This paper presents the embodiment design of an interchangeable print head based on twin-screw extrusion, specially developed to allow in-process multimaterial mixing and direct deposition of the product to structure three-dimensional (3D) parts. The print head focus on research applications with middle-end 3D printers. Commercial extrusion-based 3D printers have limited applicability due to the scarce variety of plastic filaments available. In that context, one important trend for the advance of additive manufacturing (AM) is the design of systems capable of using alternative material types in different states. The systematic process is presented as a case study and brings together concepts from mechanical design and polymer processing. The main contribution of this paper is to provide general guidelines to be used on similar projects, in view of the crescent demand for more adequate and flexible additive processes.

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.

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