Research On Optimized Design Of Multi-stage Cylinder And Chains Of Aerial Platform Fire Truck

Aerial platform fire truck is a special equipment for fire-fighting of high architectures and performing aerial work. The vertical working height of an aerial platform fire truck can range from tens of meter to almost100meter determined by the combination type and the layout of inside structures of booms. As the main style of boom, with the characteristics of small dimension and light weight, the box telescopic boom is widely used in mobile hoisting cranes, aerial work machineries and fire-fighting equipments. The key technology of telescopic boom is telescopic mechanism, the style of which could influence the boom force and performances of the overall machine directly, therefore researching on the telescopic mechanism of telescopic boom is of great importance.The thesis takes the telescopic mechanism of1st boom of aerial platform fire truck as the researched object and studies the variability of the chain force of synchronous telescopic mechanism. The optimization is carried out with the target of minimizing the chain force. The main research work and contents of the paper are as follows:(1) To realize the synchronous telescoping of booms, principle of telescopic mechanism composed of muti-stage cyclinder is researched and the functions of every chain is analyzed in detail.(2) Through constructing static model of1st boom using the balance principle of forces and moments, the boom combination type is analyzed under maximum chain force, then the dangerous working condition is comfirmed to improve the accuracy and feasibility of optimal calculation.(3) By analysis, the influence on the chain force trends is determined by changing sectional area ratio of muti-stage cylinder, inner diameter of the cylinder, thickness of the cylinder and location of the chains. As a result, the general design rule is acuired which lays the foundation of the optimal design.(4) The chain force trends under the different working conditions based on the genetic algorithms is analyzed. The optimization is carried out with the target of minimization of the chain force and constraints of the strength of cylinder and stability of piston rod of the muti-stage cylinder in order to select the model of the chain according to the optimal calculation result. The paper provides a reference for the optimal calculation problem of force of the chains used in the synchronous telescopic mechanism of aerial platform fire truck boom, which also provides a reference for the similar product design.