| Large scale belt conveyor were demonstrated to present more and moreobviously dynamic problems, even resulting in serious safety accidents such asbroken belt, when it is running, especially in the process of transition. Currently,the static design is still a main research content in the calculation and design ofbelt conveyor.It ensured the safe and reliable operation of belt conveyor mainlythrough increasing the safety factor,and ignored the vibration characteristics inthe transition process.So it has great significance to investigate the dynamiccharacteristics of large scale belt conveyor in the further research. In order tomake the controlled driving system satisfy the dynamic requirements of beltconveyor, the dynamical vibration problems of large scale belt conveyors arestudied in this thesis by combining theories, experiments and cases. The resultsof this thesis can provide theoretical supports for the research and developmentof long distance, heavy load and high-speed belt conveyor.The elastic catenary parameter equation of the inter-roller conveyor beltwas established based on the catenary theory. The sag condition for minimumtension of conveyor belt was suggested by taking account of the elasticity modulus. The maximum sag formula was obtained and its accuracy wasanalyzed and verified through cases and simulation results. The analytical resultsprovide a theoretical basis for accurately calculating the minimum tension underthe condition of sag.In order to master the dynamic characteristics of large scale belt conveyorin the transition process, the viscoelastic dynamics equation of longitudinalvibration of the belt conveyor was established in the thesis based on viscoelasticdifferential constitutive equation of conveyor belt. The analytical solutions ofdynamic displacement and tension were obtained under different boundaryconditions.The various factors influencing the longitudinal vibration of beltconveyor was discussed. The control strategy was proposed to reduce thelongitudinal vibration of large scale belt conveyor，and the control method offull torque at zero speed could be used for the downward belt conveyor underextreme conditions. Meanwhile, the validity and superiority of the controlstrategy were tested further through the experimental and case studies.Accordingto the process of dynamic equation of longitudinal vibration,the general methodwas putted forward which is suitable for the longitudinal vibration of theviscoelastic solution or elastic rod,and gave the theoretical method to researchthe similar system.In order to overcome the secondary accident of belt break caused by theexcessive dynamic tension of the large scale belt conveyer vibration, the designprinciple of belt break capture device for belt conveyor was put forward in the thesis.The design principle is that the capture system implements the fast,reliable and effective capture for conveyor belt under the condition of theaccurate judgment for break belt occurring. The hydraulic wedge belt breakcapture device under the condition of multiple signal detecting for the wholesection was developed.Meanwhile, the theoretical, simulation and experimentalstudy showed that the best capturing effect could be obtained when theself-locking was12°and the capture time was only0.75s, which offering atheoretical foundation and technical support for the design and development ofbelt break capture device.The research results in this thesis putted forward the appropriate controlmethods to reduce vibration problems in the transition process of the large scalebelt conveyor to some extent and gave the theoretical basis to the design anddevelopment of the large scale belt conveyor. |
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