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چکیده
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Prediction of curing time, which plays an important role in the quality of the mechanical properties of rubber parts, is always one of the most important issues in the rubber industry. By doing this prediction using numerical methods, it is possible to save a lot of time and costs of laboratory and production and the quality of products can be higher. In addition, it is easy to estimate the curing time of complex parts.In this research, the results of numerical solution of the rubber curing process in the production of an automotive part are reported and discussed, taking into account the real properties of the existing mixture. In this study, at first, the parameters of Kamal-sourour model are obtained using rheometric test laboratory results using MDR2000 device (Figure 1&2). This system has a movable sealed and heated mold without rotor. The sample is placed in a chamber containing hot molds. The lower mold oscillates at a certain frequency and its reaction torque in the upper mold is calculated as an indicator of the rate of curing progress. After placing the sample in the lower mold, the half-cavities of the molds are closed by an air cylinder. The rubber starts to harden and the bottom mold oscillates. The torque required to oscillate the mold gradually increases with the firing of the rubber sample. The amount of torque is measured by an electronic system and at the same time the torque-time curve, known as the rheometric curve, is displayed by a computer. Also, to determine the specific heat of the rubber, a calorimetric test is used using the DSC-60 system, and the specific heat values of the tire are calculated in terms of temperature in a laboratory. To calculate the curing time by laboratory method, the different curing times are selected and the desired part is subjected to a strength test. Each time that showed a higher strength, is selected as the experimental curing time. This test is the criterion for calculating the curing time in complex rubbery parts with non-uniform thickness for which the rheometric testing is not possible.Then, the equations related to rubber curing, which include heat transfer and curing kinetics equations, are solved with using fluent software and curing subroutine. Then the curing time for the desired part is compared with the experimental results. The results obtained from the numerical simulations show that the calculated time to reach curing is in good agreement with the laboratory results, numerical solution have the 4.8% error and this method can be used as an alternative laboratory method to determine the curing time and mechanical properties of rubber parts.
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