The Gripping Mechanism Analysis And Study On The Device Of Pile Upending Gripper

The underwater installation of marine foundation piles is one of the key technologies in the installation of offshore platform and offshore wind turbine.Because marine foundation piles have several characters,such as large diameter,long length and heavy weight,it is more difficult to install them.The pile upending gripper clamps and turns foundation piles from horizontal to vertical position.It reduces installation difficulty,raises installation efficiency and provides facilities for next operations,such as pile driving.In a word,it has practical significance for the installation of foundation piles.The topic is from the National Natural Science Foundation of China project “ Research of analysis and experiments of gripping and bearing mechanism for large-scale holding and lifting tools on ocean ”.The research purpose is to analyze the gripping and bearing mechanism of the pile upending gripper,which provides theoretical basis for optimization design and marine engineering project.In this paper,the current domestic and foreign research status of the pile upending gripper was analyzed.According to the function and design requirements,workflows and a general scheme for the pile upending gripper were proposed,including the research on the design of virtual prototype,hydraulic system and control system.In order to ensure the stability of foundation piles,this paper used the theory of elastic thin shells on the analysis of the local deformation of the clamped piles,studied the stress distribution on the radial cross section of the clamped piles,and determined the critical clamping force of the pile upending gripper.The influence factors of the deformation and stress of the clamped piles were studied by the finite element simulation.And the reasonable loading mode was found,which can reduce the deformation and stress of the clamped piles.When the pile upending gripper clamps foundation piles,the teeth of embedded block embed in the foundation pile to increase the friction and bear the foundation pile gravity.The embedded mechanism,the foundation pile gravity distribution among the teeth and the stress distribution of the tooth were studied by the theory of elastic-plastic mechanics.The influence factors of the embedded performance,bearing performance and stress distribution of the tooth were studied by the simulation.The relationship between embedded depth and load,angle of tooth profile was validated and the embedded performances of linear and ring type of the tooth were compared by the experiment.The simulation of the hydraulic circuit was done by using AMESim software to ensure the reliability of the hydraulic circuit used in the pile upending gripper,which included the performance of the locking circuit of the jaw opening hydraulic cylinder,synchronization circuit of the clamping hydraulic cylinder and synchronic control circuit of the upending hydraulic cylinder.Moreover,the visualization of the control system was designed by using LabVIEW software,which can control and monitor the pile upending gripper simply and visually.