The Study Of Heat Transfer Characteristics Of Tire During Vulcanization

With the growth of national economy, the auto industry has obtained the rapid development in the several dozens years, more and more private cars have entered thousands of ordinary families. The requirements for tire quality need to be improved because of the rapid development of highway and the improvement of road conditions, resulting in the enhancement of speed.Vulcanization is the last procedure of the tyre manufacture and vulcanization process directly affects the tyres production efficiency and the tire quality as well as the energy consumption. The existing tyre vulcanizing craft exist uneven sulfide shortcomings. In order to improve the vulcanization craft and uneven sulfide, it is necessary to explore the true vulcanization process of tire in the process. Many scholars at home and abroad have done a lot of research in vulcanization medium and equipment to improve the tire curability. At the moment, the experiment measuring and the computer numerical simulation technology were used for discussing vulcanization process. And computer numerical simulation is used widely because the temperature field got by experiments is not consistent with the true temperature field in actual production,and needs long time,high cost and complex operation.In this paper, 11.00 R20 S815 all-steel radial tire is taken as research object and the thermal physical property of rubber is tested. Vulcanization temperature field is analyzed by simulating the tire vulcanization process with Fluent and the temperature of each point in tire is tested by experiments and the results were compared. On that basis, the factors that affect the vulcanizing degree were analyzed. It provides a feasible reference for improving tire vulcanization process.(1) Thermo-physical properties in different parts of tire rubber were measured by Nanoflash^TM LFA447 in the curing process, the relation curve of thermo-physical properties on temperature was obtained, and the linear relations of heat conductivity and specific heat of rubber on temperature were obtained by the regression analysis. (2) Using the finite element software to build a two-dimensional model of the 11.00 R20 S815 tires, and curing temperature field distribution was predicted by simulating the tire vulcanization process with Fluent. The temperature distribution and variation curve of measuring points were obtained in the curing process. In order to verify the accuracy of the model, it is conducted to compare the experimental value with simulated value. Find both with good consistency, so it shows that curing temperature field simulation technology can truly reflect the actual tire curing conditions. On that basis, the influence of the thermo-physical properties of rubber on curing temperature field of tire was discussed, and the influence of"Effect after sulfide"and the initial curing temperature on the cure state was also studied. The research conclusions as follows:①During the vulcanization, There is a obvious gradient in the tire, and vulcanization process in each place of tire is very different. Tire crown and shoulder are far away from the heat source and the heating speed is less than tire side and bead, so when the latter have begun to vulcanize, and cooling speed is also slow, the time lag is obvious, so when the vulcanization in other parts is end, the reaction of these parts is still in sulfide, therefore effect after sulfide of these parts cannot be ignored, and vulcanization homopolymer continue to release which makes temperature continues to rise, and become the new heat, and heat to the surrounding units. The each part vulcanizing degree of tyre is fairly unbalanced.②"Effect after sulfide"has some influences on vulcanizing degree of each place in tire. So, in the actual production, effect after sulfide can be used to shorten vulcanization heating time, which can improve production efficiency and save energy.③The relative vulcanization is closer and closer in different places with the increase of initial temperature, In other words, vulcanizing degree was much more even with the increase of initial temperature, which can reduce over sulfur and owe sulfur degree. And it can also shorten the heating time within vulcanizing machine, to improve the production efficiency.(3) Mechanical properties of different tyre in different vulcanization is tested to research the ifluence of over and owe sulfur on the quality of tire.(4) The variable temperature vulcanization is discussed. The beginning temperature is higher to improve heat transfer and temperature and shorten vulcanization time, while the later cooling can also improve vulcanization uniformity and equipment utilization rate.(5) In the end of paper, three main vulcanization ways in the tire industry are compared. The external heating mode makes the temperature field in heat uneven because of the low heat conductivity of rubber. In order to solve this problem, the way of vulcanization in the microwave heating is put forward and the feasibility of tire vulcanizing with microwaves is simply introduced.