| 06Ni9 steel is a special high alloy steel with low sulfur,low phosphorus and low carbon.Because of its high strength and toughness at very low temperature,it has become a widely used structural material of liquefied natural gas(LNG)storage and transportation equipment in the world.However,the surface quality requirements are very high,06Ni9 steel plate has been in different degrees of damage in the process of loading and unloading.In order to meet the needs of 06Ni9 steel plate transportation,various steel plate loading and unloading processes have appeared successively,but now,there are still their own limitations.The traditional operation mode has low cost,but the operation is difficult and has great damage to the steel plate.The emergence of magnetic sling and vacuum sucker sling solves the problem of steel plate hoisting damage,but they are the special equipment,not all enterprises can bear the large cost,and the operation efficiency is low.According to the technical performance,transportation specification requirements and the requirements of low damage hoisting of 06Ni9 steel plate,the following research has been done in this paper:Firstly,from the analysis of the performance and transportation requirements of 9Ni steel plate,combined with the logistics scheme of Guangxi beihai LNG storage tank steel project of Anshan iron and steel co.,ltd,the original logistics scheme was optimized,and a low damage sling was proposed to ensure the hoisting quality of 9Ni steel plate.Through the analysis of contact deformation of metal binding surface,it is required that the steel plate should be controlled in the elastic contact deformation stage,and the bonding strength is less than the yield strength of the material.Using AHP to evaluate the logistics efficiency of the two logistics schemes before and after optimization,six indexes including transportation quality,transportation time,loading and unloading quality,loading and unloading time,process complexity and logistics cost were established,and the evaluation results of optimized scheme weight 0.5498 and original scheme weight 0.4502 were obtained.Secondly,the principle of sling design was determined,the conceptual model of low damage sling was given according to the design principle,and the theoretical model of the whole sling was established.Through theoretical calculation,the relationship between the structural parameters of the sling was given,and the basic structure of the sling was determined.Based on the finite element method,the 3D digital model of the sling was established by using Pro/E,and the simulation analysis was carried out under the maximum load state by using ANSYS.According to the analysis results,the topology optimization was carried out with the goal of 50% weight reduction by using the ANSYS topology optimization function.The optimized model was simulated and analyzed under the maximum load state again,and the analysis results met the requirements.06Ni9 steel plate low damage sling optimization scheme was feasible.Finally,Q345 steel has been selected to make sling.According to the weldability of Q345 steel,selected J507 welding rod,completed the welding work.Since there has been no shipment of 06Ni9 steel plates recently,Q345 steel plates with material properties lower than 06Ni9 steel plates were selected for loading operation at the port,and the weight of each lifting steel plate should not exceed 15 t.Compared with the original steel plate hoisting,the loading time of 1000 t steel plate was shortened from about 1d to about 4h,and the full load rate of the ship was 100%.No visible hook marks were found on the surface of the steel plate,the operation process was simple,and the low-damage hoisting of the 6Ni9 steel plate was realized. |
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