Pierre Mousseau

Inverse heat transfer analysis in a polymer melt flow within an extrusion die

In forming processes like the extrusion of polymers, the temperature profile in the polymer melt flow through the die can be quite sharp, due to high viscous dissipation and very low heat conductivity. To predict accurately the temperature rise, the inlet temperature profile has to be taken into account. This profile is generally unknown because for creeping flow the temperature field is affected far downstream from the entrance of the die. This numerical study aims to restore the temperature field within the polymer from temperature measurements taken inside the die. The polymer flow is assumed to be an incompressible steady laminar flow of a Newtonian fluid. The numerical solution of the inverse problem is computed by using a classical conjugate gradient method. The analysis is important to decide the location of the thermocouples in an experimental die. The feasibility of restoring the temperature profile is illustrated for different thermal and flow conditions.

Thermal and Kinetic Modelling of Elastomer Flow—Application to an Extrusion Die

This paper reports and discusses the thermal and kinetic behaviour of elastomer flow inside an extrusion die. The reaction progress through the runner was modeled by using a particle tracking technique. The aim is to analyze viscous dissipation phenomena to control scorch arisen, improve the rubber compound curing homogeneity and reduce the heating time in the mould using the progress of the induction time. The heat and momentum equations were solved in three dimensions with Ansys Polyflow. A particle tracking technique was set up to calculate the reaction progress. Several simulations were performed to highlight the influence of process parameters and geometry modifications on the rubber compound thermal and cure homogeneity.

Estimation Of Rheological Law By Inverse Method From Flow And Temperature Measurements With An Extrusion Die

Simulation quality is determined by the knowledge of the parameters of the model. Yet the rheological models for polymer are often not very accurate, since the viscosity measurements are made under approximations as homogeneous temperature and empirical corrections as Bagley one. Furthermore rheological behaviors are often traduced by mathematical laws as the Cross or the Carreau‐Yasuda ones, whose parameters are fitted from viscosity values, obtained with corrected experimental data, and not appropriate for each polymer. To correct these defaults, a table‐like rheological model is proposed. This choice makes easier the estimation of model parameters, since each parameter has the same order of magnitude. As the mathematical shape of the model is not imposed, the estimation process is appropriate for each polymer. The proposed method consists in minimizing the quadratic norm of the difference between calculated variables and measured data. In this study an extrusion die is simulated, in order to provide us...

Estimation of the initial temperature field during cooling of a 1-d three layer body

A method is developed to determine the initial spatial distribution T 0(x) of the temperature field in the central layer of a body from temperature measurement histories recorded in both side layers of the same body. The resolution of this inverse heat conduction problem is based on the minimization of a L-S criterion by using conjugate gradient algorithms. The practical case involving non perfect thermal conditions between the layers is analyzed.

Design and thermal analysis of a mold used in the injection of elastomers

In the process of injection molding of elastomers, improving the energy efficiency of the tools is a current challenge for industry in terms of energy consumption, productivity and product quality. In the rubber industry, 20% of the energy consumed by capital goods comes from heating processes; more than 50% of heat losses are linked to insufficient control and thermal insulation of Molds. The design of the tooling evolves in particular towards the reduction of the heated mass and the thermal insulation of the molds. In this paper, we present a complex tool composed, on one hand, of a multi-cavity mold designed by reducing the heated mass and equipped with independent control zones placed closest to each molding cavity and, on the other hand, of a regulated channel block (RCB) which makes it possible to limit the waste of rubber during the injection. The originality of this tool lies in thermally isolating the regulated channel block from the mold and the cavities between them in order to better control t...

Prediction of thickness distribution of thermoformed multilayer ABS/PMMA sheets

In thermoforming, one of the main difficulties is to avoid the presence of weak thickness in the most deformed zones. After the heating stage, a bubbling step, leading to a first rate of deformation, is often used. In this work, we assess how the initial bubbling deformation can be controlled in order to obtain a homogeneous final thickness of the product. Experiments are performed on a multilayer sheet product. An industrial mould, corresponding to a casing of a non-licensed car, was adapted on a lab thermoformer. After presenting experimental thermal profiles of the multilayer sheets measured during the heating stage, a first geometric model is investigated to predict the thickness distribution. Numerical results are compared with measurements.

Thermo-Kinetic Analysis of Liquid Silicone Rubber

Modeling and optimization of LSR parts require an accurate kinetic modeling of the material crosslinking. Calorimetric and mechanical measurements for different temperature ramps are used in order to calculate the crosslinking extent as a function of time and temperature. These measurements are numerically treated in order to determine the parameters of a representative model. The chosen model will be used to simulate a LSR molded parts and design a LSR controlled molding setup.