Study On The Shipbuilding Compensation Of Certain Types Of Bulk Carriers

Shipbuilding accuracy control technology is the foundation of a modern shipbuilding modeconversion and outfitting coated shell integration, has been widely used in domestic and foreignshipyard. Putting the correct compensation is the core content of the precision control, closelyrelated with the level of shipbuilding technology. Combined with the corporate practice, studyinga reasonable dimension compensation is of great significance to improve shipbuilding quality,minimize on-site correction of the assembly operations, shorten the shipbuilding period, andlower the production costs.This paper was based upon the scientific and technical personnel services business actionprojects—Use of the digital technology to achieve non-allowance hull construction，which wassupported by the Ministry of Finance, Ministry of Science and Technology (Finance Education[2009] No.365)。 Combined with the actual production status quo, and on-site collectedthree-dimensional sample data, to establish the mathematical model of compensation bymathematical statistical methods, dimension chain theory and data mining technology to resolvethe actual ship construction problem of machining tolerances and welding heat distortion due tocutting, assembly, welding, etc. Actually, leading the hull sections with non-allowance on theberth gradually to the development of the non-allowance construction. This thesis mainly studiesare as follows:1、Statistical analysis of shipbilding errors. For the key technologies of calculating theamount of compensation, taking a layered approach to collect the error data in the hullconstruction process, and eliminating the careless errors, and using the method of mathematicalstatistics to determine the distribution of errors. Using of the least squares method to judge thehull baseline processing straightness deviation and the sections flatness deviation, introducingthe statistical process control theory to the shipbuilding production, according to the shipbuildingcharacteristics, making the quality control charts to find and eliminate abnormal factors to ensurethat the process in a stable state.2、Implementation of the technics program to allocate compensation. On the foundation ofresearching and referencing specifications and industry standards and combined with productionpractices, research and develop accuracy standards for the enterprise and guide theimplementation of shipbuilding precision technology. Establish the cumulative error model bysize chain theory and regression analysis, and using Monte Carlo random sampling method, to obtain the regulation of error propagation and tolerance distribution in the hull construction, andcalculate and allocate the compensation by the application of dimension chain theory, to makethe implementation of reasonable accuracy process.3、Finite element analysis of bending proeess of three-roller symmetrical plate bendingmachine. According to the elastic-plastic theory and considering the effect of contact friction, useof ansys software to create a finite element model of a three-roller symmetrical plate bendingmachine in a shipyard, and to carry out analysis and dynamic simulation of hull high strengthsteel AH32roll forming. Contrast with the traditional elastic-plastic theoretical, findings showthat the finite element model is correct. according to the result of several simulation analysis,using the least squares vector machines to establish math model of steel plate roll bending radiusabout the roll down amount and the thickness, to guide the automatic control of the changablecurvature sheet processing.4、Create the mathematical model to forecast the transverse contraction of butt welding.Extracting the key factors that affect the butt welding shrinkage by fuzzy analytic hierarchyprocess, then, establishing of the BP neural network model, and using a genetic algorithm tosearch the optimal network initial weights and thresholds, to provide quantitative basis forplusing the correct butt welding compensation.