Research Of Flexible Luffing Safety System Of Portal Slewing Crane

When luffing mechanism of flexible luffing portal slewing crane fails, the boom will be out of balance and it may cause an accident. In order to avoid similar accidents, some cranes to install a security cable. Actual boom broken case shows that the limitations of this solution is rather obvious. For setting up safety rope reasonably, dynamic behavior of the boom under the function of safety rope in accident condition is needed to study. In allusion to the limitation of safety rope, a new boom safety solution which consists of duplicate luffing system and normally closed disc type safety brake is proposed. In order to verify the feasibility of the new boom safety system and determine key parameters, the study of dynamics behavior of boom under the function of safety system is necessary.Boom drop caused by the failure of luffing system is very dangerous, so luffing system safety can't be studied by test method. In this case, the dynamics simulation of boom safety system is the main basis to solve the problem of setting parameters of safety system.In this paper, a flexible luffing portal slewing crane using a safety rope is taken as the research object. The flexible multi-body dynamics simulation model of the safety rope systems is established by ADAMS and ANSYS. Firstly, dynamics simulations of crane under the accident condition and the ideal condition are carried on, based on the obtained dynamics behavior of boom, the system safety under different conditions is discussed. Secondly, the flexible multi-body dynamics simulation model of new boom safety system composed by duplicate luffing system and normally closed disc type safety brake is built, the key parameters affecting safety behavior are tested in field. The simulation and analysis under the most dangerous condition is carried on, and the feasibility of the safety system is studied. And then, determine the scope of the studying parameter, and new crane boom safety system under different parameters is simulated. Taking boom structure strength and luffing rope breaking force as limiting conditions, with reference to the boom limiting angle of elevation, effective parameter scope which can make new crane boom safety system feasible is got. Finally, taking one point of effective parameter scope as parameter of new crane boom safety system, and new crane boom safety system under the parameters is simulated. Also, the correctness of the parameter can be validated.The results show that:1. Under the accident conditions, even if the safety rope can offer enough tension force for the boom, but the boom structure can't bear the impact loads caused by safety rope, so safety rope cannot ensure the safety of crane boom in accident conditions;2. If performance parameters are properly selected, new boom safety system composed by duplicate luffing system and normally closed disc type safety brake is feasible;Research methods and conclusions of this paper provide references for setting safety rope system and boom safety systems reasonably.