The Mechanism Synthesis and Dynamic Research for Aerial Working Platform
|School||Harbin Institute of Technology|
|Course||Mechanical Design and Theory|
|Keywords||Aerial work platform cylinder-type mechanism synthesis kinetic research dynamic characteristic analysis|
The cylinder-type aerial work platform studied in this paper, which is used for the maintenance of the target chamber in large lasers, is a new crane for special purpose. This platform has the characteristics of small retraction size, big expansion range, working range and so on, and is applicable to the working conditions with narrow working space and strict size requirement, so it has strong use value.As an independent machine, this platform can realize all the functions of ordinary aerial work platform, and can simultaneously adapt to the special working environment with narrow working space and high cleanness, it’s an aerial work platform with special functions. The configurations, kinematics and dynamics of motion mechanisms in the platform are the important influence factors of the performance of the platform. To ensure the platform has a good service performance, it’s necessary to do mechanism synthesis and dynamic analysis while designing the platform.Four forms of six bar mechanism are combined through selecting the classification and distribution schemes of six-bar kinematic chain connecting rod. On this base, a new mechanism form is formed by regenerating kinematic chains, and the type synthesis of the swing arm mechanism is completed. Aiming at solving the problem that the swing arm mechanism has a great acceleration when starting and stopping, dimension synthesis is done with the rod length of six connecting rods and the position of hinge joints by using ADAMS, therefore the parametric design is realized, and the motion performance is optimized.An equivalent kinematic model of the swing arm mechanism was built up based on equivalent element integration method of planar mechanism kinematic modeling. Combining with the equivalent thought and finite element method, elements are integrated and assembled by adopting finite element method. The listing method of the second-order and third-order conversion tensor and the assembled form of the system mass matrix are presented, and the system kinematic differential equations are deduced, therefore avoiding man-made mistake in listing kinematic equations by using traditional method.The cranes’stability failure is a very important aspect in the accidental analysis of cranes. In this paper, the stability equations of box-type telescopic boom are deduced according to the friction between the joined arms. The difference of the whole instability euler critical force of boom is qualitatively and quantitatively analyzed, for which a variable cross-section trapezoid column, and the influence of cylinder and friction are taken into account respectively. Modular analysis is done to the telescopic mechanism, and modal extraction is done to the structure based on Ansys platform, and the previous fifteen-order modals of the whole machine are obtained. In addition, the character of mode shape and cause of sectional vibration are analyzed to provide a theoretical basis for the structural design and optimization.