Investigation On Heat Transfer Characteristics And Optimization Of Tire Vulcanization

This investigation take the11.00R20S815all-steel radial tire as the research object, and put emphasis on the thermo-physical properties and mechanical properties of tire rubbers and the influence mechanism of curing technological conditions on tire curing process, and take roundly research on the tire curing process by means of experiments and numerical simulation, and improves the curing technology on the basis of the research results to making sure the curing quality and increasing the curing efficiency.(1) Using the moving die rheometer to test the optimum curing time and the optimum curing interval of rubbers used in11.00R20S815all-steel-radial tire, and found that there are great differences between different rubbers on optimum curing time and optimum curing interval, and the flat period of rubber that in the out side of the tire is longer than others’.(2) Using the LFA447laser thermal analyzer to test the thermal diffusion coefficient of rubbers, and finds that the thermal diffusion coefficient of rubbers decreased with the rising of temperature, and the thermal diffusion coefficients of the rubbers that in the out side of tire are higher than other rubbers’. Using the differential scanning calorimeter to test the specific heat of the rubbers, and finds that the specific heat of rubbers rose with the rising of temperature, and the differences between the rubbers are small. Then the heat conductivity coefficients of rubbers are calculated by formulas, and the heat conductivity coefficients of rubbers rose with the rising of temperature. At last, the relational expression of rubbers’ thermo-physical properties and temperature are fitted.(3) Using the same way to measure the thermo-physical properties of rubbers that exerted a force of2.5MPa, the results show that the thermal diffusion coefficient of rubbers which are exerted a force are higher than rubbers without exerting a force, but the specific heat and heat conductivity coefficients are more lower. These results show that the curing pressure has partly influence on the thermo-physical properties of rubbers. The relational expression of rubbers’ thermo-physical properties after exerting a force and temperature are fitted.(4) Using flat vulcanizing machine to cure the rubbers used in the11.00R20S815all-steel-radial tire with different pressures, and then using the tensile testing machine and the Akron abrasion testing to test the mechanical properties of curing rubbers, the results show that the tensile strength and the300%stress at definite elongation are increased with the increasing of curing pressure, but the elongation at break, the tensile permanent deformation rate and the tear strength are decreased, and the abrasive resistance of tread rubber is enhanced with the increasing of curing pressure.(5) The physical model and the mathematical model of11.00R20S815all-steel-radial tire are created and the numerical simulation of the tire curing process are carried out, the thermo-physical properties of rubbers are uploaded with the ones of rubbers are exerted a force and the ones of which without exerting a force, and then compares the simulation results and the curing temperature testing results, the comparing results show that the results which are calculated under the condition of uploading the thermo-physical properties of rubbers that without exerting a force are approximate to the experiment testing results, so the experimental testing of thermo-physical properties of rubbers exists some errors, but the truth that the curing pressure has influence on the thermo-physical properties of rubber can not be denied.(6) The analysis of the influence of the boundary temperatures on the curing degrees of tire are carried out through numerical simulation on the basis of existing curing technology of11.00R20S815all-steel-radial tire. The results show that the temperature of superheated water has significant influence on the6#,16#,23#,10#and18#temperature testing points, the temperature of the segment mould has significant influence on the24#,18#and16#temperature testing points, the temperature of hot plate has significant influence on the8#,6#and23#temperature testing points. The relationship between boundary temperatures and heating time are analyzed, then carry out a optimizing scheme of curing technology, the scheme is to raise the temperature of segment mould by4K, to raise the temperature of superheated water by3K, and to raise the temperature of hot plate by2K, the curing time are reduced from50minutes to45minutes, the results show that this optimizing scheme is able to improve the tire curing efficiency and ensure the curing quality at the same time.