Scheme Generating Method And Experiment Verification Of Cold And Hot Loading For Forming Curved Plates Of Ship

With the development of China’s national strength and the increasing demand for oceangoing trade,the demand for ships has gradually increased.It had become one of the most difficult problems in shipyards on how to quickly manufacture ships that meet the need.Ships are usually welded by curvature plates.At present,most shipyards in China are still adopting the cold forming and line heating method to manufacture curvature ship hull plates.In the general process,the plate is first bent by cold loading to form a simple curvature,and then the formed plate is local bent or heated to achieve the required shape.Many processing methods such as three-roller bending,multi-point forming and die forming of cold forming and flame heating and induction heating in line heating are based on the accumulated experiences of workers.Thus,the forming precision and automation cannot be guaranteed,which limits the quality and efficiency of the ship manufacturing.With the increase of workers’ labor costs,it is not desirable to rely on experience achievement to obtain highprecision forming.This poses a pressing requirement for the automated processing of the plate forming.It is obvious that searching an automatic forming process and producing corresponding equipment of ship hull forming is necessary and urgent.This paper presents an automated forming method of the curvature plates with integrated hot and cold forming method and develops the corresponding prototype to realize the different manufacturing mode.The method combines induction heating and cold roll forming together and achieves a plurality of processing modes such as line heating,cold rolling,hot and cold forming and the like.The method has the advantages of low cost and diverse molding methods and can be easily realized in the automatic forming of a curvature plate of a ship compared with the traditional processing method.This paper designed the main program and the corresponding system of the forming process,developed the corresponding prototype,and tested the forming effect of the machine.The forming mechanism of the curved plate was analyzed firstly,and the relationship between the curved surface and the strain distribution was studied.Then,the principle of the forming method such as induction heating,cold rolling and the integrated loading process was analyzed,and the corresponding finite element calculation method was given.The relationship between the loading parameters and the strain distribution of the plate was obtained based on finite element calculation,and the data was generated as the base of the automatic forming.According to the strain distribution characteristics during processing,a virtual loading algorithm based on initial stress method is developed,the strain is loaded on the processed plate to obtain the deformed shape,the effectiveness of the virtual loading algorithm was verified through the experimental results.Subsequently,the path generation method based on strain distribution was established,and the corresponding parameter was obtained according to the data generated in the previous section,and the loading scheme of typical ship plate is given.Then,the system configuration and work flow of the prototype was given,the formed shape under different loading conditions was tested to verify the effectiveness of the method,and the generated loading scheme based on the target surface were verified on the prototype.