MODELING HEAT EXCHANGE OF POLYMER-BASED TOOL WHEN PRESSED INTO A CARBON CLOTH
The paper considers the heat exchange of polymer particles found on a carbon reinforcing fabric with a roller pressing these particles into a carbon cloth. Assuming that the speed of the cloth movement is rather low relative to the roller, without taking into account heat exchange of the pressed particles or the cloth and the environment, including the conveyor belt on which the cloth is located, the authors have developed a mathematical model of conductive heat transfer in the contacting roller, polymer particle and reinforcing fabric. This model includes heat conservation equations written with respect to the average temperatures of the roller, particles, and fabric, as well as boundary and initial conditions. In order to simplify calculation the authors have assumed there is an ideal thermal contact between the polymer particles and the cloth, thus, the average thickness of the pressed particles in the direction of heat propagation has been low. Therefore, it can be drawn that the layer of material particles and that of the cloth is thermally thin, and the temperature change across the thickness is negligible. As a result, the original system of three equations has been reduced to one equation with regard to the temperature of the roller. This equation has been supplemented by the corresponding boundary and initial conditions. Provided that the temperature near the roller surface varies along its radius according to the linear law, the specific heat flux on the surface of the roller has been estimated. After that, the expression is substituted in the equation of the thermal balance of a thermally thin layer consisting of particles and reinforcing fabric, which, after certain transformations, is integrated. The obtained formula for the average thickness temperature of the pressed polymer particle shows that over the time of contact of the roller with the particle, its temperature changes mainly according to the exponential law. However, as the particle transforms and flattens, the argument of the exponential function decreases, so that the thermal effect of the roller on the temperature of the particle material increases. At the same time, this decrease directly depends on the speed of the particle movement relative to the roller and the degree of its compression by the tool. Since these parameters are technological, the formula presented in the article allows the authors to reasonably choose pressing modes in accordance with existing requirements.