3D simulation of gas assisted injection molding analysis of primary and secondary gas penetration and comparison with experimental results / A. Polynkin in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 2 (06/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 2 (06/2005) . - p. 191-201 Titre : 3D simulation of gas assisted injection molding analysis of primary and secondary gas penetration and comparison with experimental results Type de document : texte imprimé Auteurs : A. Polynkin, Auteur ; J. Sienz, Auteur ; J. F. T. Pittman, Auteur Année de publication : 2005 Article en page(s) : p. 191-201 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Techniques for the three dimensional simulation of gas assisted injection molding (GAIM) are presented, including analysis of primary and secondary gas penetration and the use of time and position dependent heat transfer boundary conditions, computed in a segregated 3D analysis of conduction in the tool, through many cycles of moulding. Predictions are compared with results of experimental trials using a mould tool with a glass window that allows video recording of the process. Accurate agreement is obtained for gas penetration distances in primary and secondary penetration and for the forms of the gas channel cross sections, in a part that incorporates typical features of a GAIM application. The success of the simulations relies on careful detailing of the computational model and numerical procedures, including the use of dynamically updated flow and heat transfer boundary conditions, the use of sufficiently high resolution meshes, and efficient, high accuracy iterative solution techniques. DOI : 10.3139/217.1878 En ligne : https://drive.google.com/file/d/1uwhXsKk0lkdytilr4nIqRTQMAXRHvXdf/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3080 [article]

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Computer aided optimisation of profile extrusion dies / I. Szarvasy in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 1 (03/2000)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XV, N° 1 (03/2000) . - p. 28-39 Titre : Computer aided optimisation of profile extrusion dies : Definition and assessment of the objective function Type de document : texte imprimé Auteurs : I. Szarvasy, Auteur ; J. Sienz, Auteur ; J. F. T. Pittman, Auteur ; E. Hinton, Auteur Année de publication : 2000 Article en page(s) : p. 28-39 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : An objective function is proposed for use in optimisation of profile die design, and defined in terms of mass flow rates to topological partitions of the profile cross section. In a series of uPVC extrusion trials its dependence on land channel height is investigated for two profiles to assess its suitability for gradient based optimisation of flow distribution. Pre- liminary finite element flow simulations are carried out, and comparisons of computed and experimental objective function values show that the mathematical modelling should be extended to include extensional effects and draw down at the die exit. Examination of the experimental profiles indicates the limitations of die optimisation in determining the detailed geometry of the finished profile cross sections. DOI : 10.3139/217.1577 En ligne : https://drive.google.com/file/d/1FiVPGZiYwzU51bv5zYRQu2EosOy9AoAE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16071 [article]

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Gas assisted injection molding of an industrial - Part : 3D simulation provides virtual molding trials / A. Polynkin in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 2 (05/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 2 (05/2007) . - p. 173-178 Titre : Gas assisted injection molding of an industrial - Part : 3D simulation provides virtual molding trials Type de document : texte imprimé Auteurs : A. Polynkin, Auteur ; J. Sienz, Auteur ; J. F. T. Pittman, Auteur Année de publication : 2007 Article en page(s) : p. 173-178 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Techniques developed for three-dimensional simulation of gas assisted injection molding of thermoplastics are here extended to a complex industrial application, a car door handle, providing uniquely detailed insights into the molding process. Handling of the three stages of the process – plastic filling, and primary and secondary gas penetration – is described in terms of the boundary and initial conditions applied. Predictions for plastic filling patterns are compared successfully with molding results, and provide detailed forewarning of potential problems due to weld surfaces and air-traps. Particular emphasis is placed on accurate modeling of secondary gas penetration, which is also validated against practical results. A further novel feature is the export of an STL model of the gas core, providing a CAD model of the finished molding for subsequent in-service analysis. DOI : 10.3139/217.0996 En ligne : https://drive.google.com/file/d/1QCsBJukQqvheDu_VjpUsBCqh6zI_V-3-/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2757 [article]

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Modelling of cyclic 3-dimensional heat transfer in injection moulding / A. Polynkin in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 4 (12/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 4 (12/2004) . - p. 408-418 Titre : Modelling of cyclic 3-dimensional heat transfer in injection moulding Type de document : texte imprimé Auteurs : A. Polynkin, Auteur ; J. F. T. Pittman, Auteur ; J. Sienz, Auteur Année de publication : 2004 Article en page(s) : p. 408-418 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A detailed 3-dimensional analysis of cyclic heat transfer in a complex injection moulding mould tool has been carried out, using a general-purpose commercial heat transfer code (FIDAP). A novel, generally applicable technique for modelling of heat loss to ambient from the tool parting surfaces is introduced, to facilitate inclusion of the mould-open period in the modelling. Simulations are continued through 30 cycles of moulding, to attainment of steady periodic conditions. During this period temperatures at the polymer-steel interface rose by between 10°C and 40°C above the coolant temperature. At the start of cooling, values of cavity surface heat transfer coefficients referred to the coolant temperature ranged from approximately 4000 W/m2K to 400 W/m2K, with the highest values occurring directly below the cooling channels and the lowest near a heated sprue bush. At the end of the cooling period, values at each location had dropped by approximately an order of magnitude. These results illustrate the limitations of plastics cooling analyses that use constant values of temperature or heat transfer coefficients as boundary conditions on the cavity surface. Comparison with results obtained omitting the modelling of the mould-open period shows how, in the latter case, higher tool temperatures are attained in the steady periodic conditions, and a larger number of cycles are required to reach steady periodic conditions. DOI : 10.3139/217.1850 En ligne : https://drive.google.com/file/d/1n4UwcIUjZZod03VKA1Ux6o9qkx3-arVr/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3275 [article]

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Production of pipe with uniform wall thickness : how to compensate for gravity sag / J. F. T. Pittman in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 3 (09/2000)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XV, N° 3 (09/2000) . - p. 260-267 Titre : Production of pipe with uniform wall thickness : how to compensate for gravity sag Type de document : texte imprimé Auteurs : J. F. T. Pittman, Auteur ; A. Farah, Auteur Année de publication : 2000 Article en page(s) : p. 260-267 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A detailed simulation of the cooling process in the production of plastic pipes has been used to gain insights into the problem of gravity flow or sag, which can lead to troublesome wall thickness variations in thick walled pipes. It is shown how the simulation can be used in an iterative, forward-backward calculation, based on the time reversibility of the creeping gravity flow problem, to calculate the initial extrudate wall thickness profile that the die must deliver to precisely compensate for sag. For pipes with particularly thick walls, this calculation shows that no compensating initial profile exists whilst conventional cooling arrangements are used. Reduction of the cooling rate of the lower part of the pipe promotes wall thickness uniformity and the existence of a compensating profile. Means for achieving the required initial profiles are discussed, and the need for an integrated view of the design and operation of the die and cooling line in understanding and overcoming the effects of sag is emphasised. Note de contenu : - Computation of initial wall thickness profiles to compensate for sag - Circumferential variation fo cooling rates to promote wall thickness uniformity DOI : 10.3139/217.1597 En ligne : https://drive.google.com/file/d/1YzDagGkVlMlpBjM5nhIGH3joPrehEsVc/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15830 [article]

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