Research On The Key Technology Of Accuracy Control In Hull Assembly

In the process of shipbuilding,the dimension's accuracy can be controlled by the accuracy control combined with the dimensional chain,tolerance design and the deviation prediction.This paper focuses on the dimension chain's application,tolerances' design and deviations' prediction in the hull's construction.Firstly,the differences between the mechanical parts' assembly and the hull parts's assembly will be discussed,the mature dimensional chain will be used in the accuracy control of hull.In the construction of the dimensional chain, the welding deformation that can't be neglected as the loop of chain will be considered,then according to the size deviation of hull construction,the dimensional value will be added to the basic size of part.All the value of compensation will be the compensational loop in the dimensional chain,the compensational loop should be covered by the follow-up processes.Finally,a simple assembly of hull bottom will be as an example of dimensional chain's establishment.In the pursuit of product quality, the traditional tolerance model based on the processing cost ignores the relationship between the tolerance and the quality of the product,it can not design tolerance accurately.Firstly,a tolerance design's model based on quality loss and manufacturing cost will be put forward,then the model's feasibility will be analyzed,the experimental method of uniform design's will be used in confirming the parameters of standard particle swarm algorithm,the particles that fall into the local optimal will be replaced;finally,the particle swarm algorithm will be used in optimizing the tolerance design model,a flat bottom straight section will be as an example of the algorithm feasibility's verification.A method based on the state space model was shown to model the variation propagation of the bottom block assembly in shipbuilding.First,the part's accumulative error and part's locating error and welding deformation error and relocation error were analyzed.The welding deformation variation mainly comes from butt-joint deformation and corner-joint deformation.Those dimensional variations increased,decreased,stacked-up,propagated,and became the final product variation when the process was completed.Secondly,a state space model was built to describe the variation propagation,the key point variation of the part will be as a state vector and the measurement variation will be as an output vector.Finally,a bottom block erection instance was described to illustrate and verify the application of this model.VB was used to develop the system including the automatic generation of the dimensional chain,the calculation of tolerance's optimization and the error of prediction,the tolerance optimization model of different parameters will be established to design tolerances and error deviation.