Research On Production Organization Of Ship Pipe Fittings Cell Processing Under Productivity Fluctuation

The ship’s armoring operation runs through the entire process of ship construction,usually accounting for 50%～60% of the total ship construction,particularly in complex and special types of ship construction.The processing and installation work of pipe fittings in armoring operations accounts for 40%～45% of the total armoring operations,and its production efficiency has a more important impact on the shipbuilding cycle.The production capacity of pipe fittings is affected by many factors,which have dynamic characteristics and always fluctuate in production practice.Production organization is one of the main factors affecting capacity fluctuations.As a sub-manufacturing workshop of shipyards,many shipbuilding enterprises generally organize the production of pipe fittings based on the principle of process specialization.The production of pipe fittings under this traditional production mode is chaotic,and it is difficult to maintain the rhythm and continuity of the production process,which results in pipe fittings processing.In cellular manufacture,the equipment layout and logistics design of the product family are effectively organized in order to achieve fast,efficient and flexible production operations,which combines the efficiency of mass production with the flexibility of small and medium batch production.In view of the characteristics of ship pipe fitting processing and engineering,this paper proposes a unit production organization method suitable for ship pipe fitting processing.Through the optimization of cellular construction and cellular facility layout,the production capacity of pipe fitting processing system can be improved and well adapt to the changes in market demand.Based on the related concepts of manufacturing cycle and production lead time,this paper summarizes the composition of production lead time and its influencing factors,and finds that non-value-added time accounts for a large proportion in the production process.Then,based on the principle of compression production lead time,the feasibility of capacity expansion under reasonable production organization conditions was analyzed from the perspective of processing object movement mode and workshop facility layout.At the same time,in view of the existing rigid capacity description which does not conforms to the actual production,this paper combined the capacity expansion method and capacity theory under the cellular manufacture,and uses fuzzy numbers to describe the capacity fluctuation,and the semi-trapezoidal capacity membership function was obtained.On this basis,considering the multiprocess production path,processing sequence,production batch,processing time,equipment capacity,capacity fluctuation and other practical factors of the parts,aiming at the material flow and equipment load balance,the multi-objective are established in order to achieve the minimum total moving cost of the part and the equipment load balancing penalty cost.The genetic algorithm is used to solve the proposed model under certain confidence levels,specific equipment/part grouping,and optimal process path and number of part.Based on the completion of the cellular construction plan,the integrated layout of manufacturing cells was studied.In order to avoid the isolation of the cell system layout and the layout of the facilities between cells,the idea of parallel engineering was used to integrate the two stages of the unit layout,and a multi-objective cell layout optimization model with the minimum material handling distance and the optimal facility area utilization was constructed to determine the layout and location between different cells and the internal facilities of the cells.For the characteristics of multiobjective models,the particle swarm algorithm was used to solve the model to prove the feasibility of the scheme.On the basis of the above,this paper applied the cell manufacturing organization method under the fluctuation of capacity to the pipe processing workshop of Company A.The feasibility and effectiveness of the proposed method were verified by the optimized production plan obtained from this paper,which provides a certain reference for enterprises to effectively organize production and improve production capacity.