Analysis And Control Of Cold Bending Process Of Ship Pipe

Bending pipe is an important part of ship manufacturing process.In the actual process,due to the characteristics of the ship-pipe itself,it is difficult to avoid the defects of spring-back and length extension.So the method of left margin processing mode is often used in shipyard.If we use this method,we should bend many times,and after the completion of processing,the second strokes and second cut line are required.It not only leads to the waste of materials,but also restricts the speed of shipbuilding.Therefore,in the process of pipe processing,the control of spring-back plays an important role in improving the efficiency of shipbuilding and the precise forming of pipes.In this paper,we adopt the finite element software to simulate the bending process.Through changing the model parameters,researching the effect of bending angle,radius of the tube radius,axial force,relative bending parameters on the spring-back angle.Taking experiment,we verification the accuracy of this model.The main contents are as follows:(1)According to the actual processing characteristics of pipe cold-bending forming,the finite element model of pipe cold-bending forming is established.Establishing a spring-back model and carry out numerical simulation based on the cold-bending finite element model.(2)On the basis of finite element simulation,the suitable bending angle,relative bending radius,pipe radius and axial force is set,and the influence of them on spring-back angle is analyzed.(3)According to the results of finite element simulation,the main influence parameters are tested and verified.(4)Research methods which control the spring-back of pipe by finite element model.In this paper,through the analysis of the model and test validation,the following conclusions are drawn:(1)After unloading the bent of pipe,the final forming angle is linearly related to the bending angle and the line does not pass the origin.(2)The existence of axial force which shows in the form of clamping degree of work piece during pipe processing will affect the spring-back,and the larger the axial force is,the smaller the bending spring-back will be.(3)The wall thickness and diameter of the pipe have little influence on the angle of rebound,so the influence on the angle of rebound can be ignored in the actual production process.The relative bending radius has a great influence on spring-back,so its influence must be considered in the actual machining process.(4)The experimental results show that the finite element model in this paper can simulate the bending process of the pipe,which means that the finite element model has guiding value for the actual processing.