Research On Key Mechanism Of Direct-Pressure Tire Vulcanization

Precision, efficient and green-produce is the trend of tire manufacturing industry. Vulcanization is an important process of tire manufacturing. However, there are some disadvantages can’t be ignored in current curing methods. Because of the low accuracy of bladder expansion shape and uneven curing temperature, the existing tire vulcanizing machine couldn’t realize highly uniform distribution of rubber, so the performance of tire uniformity and dynamic balance are restricted. Besides, the heat of curing medium is greatly dissipated in circulation process, and the maintenance cost of pipelines is very high, which improve the cost of tire manufacturing.A novel inner mould direct-pressure mechanism used for replace the elastic bladder was developed based on the principle of direct-pressure tire vulcanization. In order to achieve energy saving manufacturing, electromagnetic induction heating technology was adopted for heating the inner mould direct-pressure mechanism. In addition, the performance of new tire vulcanizing machine was evaluated by experimental research of direct-pressure tire vulcanization and product performance testing. The main research achievements were obtained as follows:(1) Guide rail type inner mould direct-pressure mechanism was developed successfully. The new mechanism was designed according to the size of 255/30R22 95V tire. Based on the analysis of its kinematics characteristics, the mathematical models of each motion were established; key geometric parameters of mechanism were confirmed. The correctness of the approach was validated by the motion simulation of virtual prototype. By using ABAQUS software, the static strength of inner mould direct-pressure mechanism in curing process was analyzed. According to the stress characteristics, the physical construction was redesigned and reanalyzed repeatedly. Finally, a reasonable design of the inner mould direct-pressure mechanism was obtained. The successful development of this new mechanism provides an important reference basis for developing this kind of prototype.(2) Electromagnetic induction heating device for the inner mould direct-pressure mechanism was developed successfully. The scheme of electromagnetic induction heating for the inner mould direct-pressure mechanism was designed. The influences of parameters of magnetic cores, coils, and controllers on the temperature uniformity of drum tiles’surface were discussed. Analysis results indicate that the temperature difference in the longitudinal direction could be regulated in a suitable range by designing the height of magnetic cores, the inductance of coils, and the position of coils arranged on the magnetic cores reasonably. The output power of controllers is related to temperature difference in the circumferential direction of drum tiles. The effectiveness of the electromagnetic induction heating scheme was validated by the temperature measuring experiment of drum tiles.(3) Performance of guide rail type direct-pressure tire curing equipment was researched. The temperature history of tire in the entire curing process was investigated through temperature measurement. Results show that compared with the existing curing technology, temperature of each part rise significantly faster in the new method of direct-pressure vulcanization. The defect of large temperature difference between the upper and lower sidewall could be eliminated. Equivalent vulcanization effect was calculated. Results show that curing time could be shortened by using direct-pressure tire vulcanization. Tire vulcanizing experiments were performed. Results indicate that tire could be manufactured smoothly with the machine, also have good appearance quality and internal structure. Tire performance experiments were carried out Results show that the performance of dynamic balance and tire uniformity improve greatly, which indicate the novel tire vulcanizing machine can realize higher shape precision of tire and uniformity of material properties. The laboratory experiments about tire bead unseat test, strength test, high speed performance test, endurance test and low pressure performance test all reached the national standards. Results indicate that excellent products could be obtained with the novel guide rail type direct-pressure tire curing equipment.