Table 1 - uploaded by Fernando Pinho
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Source publication
A computer code, previously developed by the authors for the automatic die design, is used to optimise the flow distribution of an extrusion die, whose cross section is composed by walls with several different thicknesses (ranging from 2mm to 4 mm). The optimisations are performed using two alternative strategies: one based on die land length optim...
Contexts in source publication
Context 1
... parallel zone cross section of the extrusion die to be optimised is shown in Figure 2. It is composed by several subsections of different thickness, ranging from 2 to 4 mm, as indicated in Table 1. These values were imposed deliberately in order to promote differential local flow restrictions, situation which is intended to represent a typical profile extrusion die. ...
Context 2
... values were imposed deliberately in order to promote differential local flow restrictions, situation which is intended to represent a typical profile extrusion die. The layout adopted for the flow channel is illustrated in Figure 3, whose main dimensions are presented in Table 1. The polymer used in this work was a polypropylene homopolymer extrusion grade, Novolen PPH 2150, from Targor. ...
Context 3
... the first trial of the optimisation algorithm, a constant length/thickness ratio (L/t) equal to 15 was adopted for all ES (see Table 1); the operating and thermal boundary conditions imposed for the flow simulations are listed in Table 2. As mentioned before, the optimisation algorithm initially calculates the flow of the polymer melt using a coarse mesh which is then progressively refined as the procedure evolves towards a final solution. ...
Citations
... A penalty function was introduced to enforce a limit on the maximum allowable pressure drop in the die. Carneiro et al. [7] used 3D computational routines based on the finite volume method to optimize the flow channel of a specific profile extrusion die. The numerical results obtained are compared with experimental data. ...
THE coat-hanger melt distributor is a device commonly used in the wire coating process. Its task is to distribute the melt around the conductor uniformly. It is quite common that materials and flow rates differ from what had been specified during the design procedure. This may lead to bad performance with materials of very different rheological properties from the design material. In this article, we present an optimal design approach to avoid this loss of performances. This approach involves coupling a three-dimensional finite element simulation software with an optimization strategy based on a response surface method. The objective is to determine a coat-hanger melt distributor geometry that ensures a homogeneous exit velocity distribution that will best accommodate for a different range of materials. A coat-hanger melt distributor with a manifold of constant width is designed, and a set of flow distribution measurements is established for two different materials. The results of numerical simulation are then validated by comparison with experimental measurements. The effect of material change is also investigated. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
This article presents an experimental study on the flow balance of an extrusion die for various wood flour (WF)/high-density polyethylene (HDPE) compositions. Flow balancing, in the design of a thermoplastic extrusion die, is dependent on the material rheological properties so that a change in the material, in some cases, may result in a total redesign of the die. To investigate the importance of this particular effect, the flow balance of an extrusion die, with a U-shaped profile having uneven wall thicknesses, was undertaken. The main feature of the die was an adjustable restrictor implemented for fine balancing similar to that employed in the slit dies. The rheological influence of wood plastic composites (WPCs) on the flow balance of the die via loading various WF contents, 40, 60, and 70% by weight, was experimentally investigated; flow balancing was performed via varying the height of the restrictor bar. Interestingly, the results showed that, for a high WF content (above 60%), the issue of flow balancing for an uneven wall thickness profile is much less complicated because of the plug flow behavior of the composite. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
