Study On Key Techniques Of Automatic Processing For Line Heating

For a long time, the double-curved hull plate forming in shipyards depends on experienced workers using line heating method by manual work. With the development of modern shipbuilding technique and the transformation of shipbuilding mode, the manual and experiential technique patterns of line heating can not meet the requirement of modern shipbuilding in processing speed and quality, and it has become a bottle-neck problem which restricts the cycle and quality of shipbuilding. To realize the automatization of hull plate processing, several key techniques of automatic processing for line heating are investigated in this paper.(1) Distortion discipline of line heating for automatic processing is researchedThe main influence factors of shell plate forming by line heating are analyzed. Based on the analysis of measured data processed by the experiment machine of line heating, thickness of plate, length of heating line, processing speed and shrinkage are regarded as 4 dimensions, and the methods of vectors mapping, plane projection and conversion of coordinates are used to build mathematical models for local surface shrinkage of different thickness and processing parameters. The mathematical models are amended by BP neural network algorithm, and method of finite element numerical simulation is used to compensate the removal data and extend the applied range.(2) Optimization problem of technique parameters for automatic processing of line heating is investigated by using Hiberarchy Genetic Algorithm(HGA)Fit goodness of shrinkage ratio curve and plate processing time are taken as two objective functions to establish the mathematical models of the optimization issue for technique parameters of line heating, and then the two-objective optimization problems are transformed into single objective one by changing power coefficients. According to mathematical models of distortion discipline for line heating given above, the interpolation function with cubic spline is used to change the objective function into individual fitness function of colony based on HGA. Combining three parameters, which include the number of heating lines, the space between lines and the shrink quantity of line, HGA coding is constructed, and then three parameters of automatic processing for line heating, such as processing speed, length of heating line and shrinkage of heating line, are gained. Finally, optimization system of technique parameters for automatic processing of line heating is developed by the software of Visual C++6.0.(3) Inspect method of forming after automatic process of line heating is researched According to hull plate surface data measured by the intelligent robot of line heating,space coordinate conversion method is used to establish plate coordinate system. The surface of the plate is simulated by the method of Ferguson surface, and template lineconcept is defined. Utilizing parameter spline curve, space coordinate conversion, the forming both in transverse and longitudinal direction, as well as distortion of the processed hull plate are inspected, which is the foundation for carrying out parameter prediction in second processing.The mathematical models of distortion discipline and the technique parameter optimization algorithm of line heating presented in the paper have already applied to ship plate production in Dalian New Shipbuilding Heavy Industries CO.LTD, and can obtain good results. The inspect method of forming after automatic process of line heating has also verified by experiments.