Research Of Sheet Metal Expansion Method Considering The Variation Of Neutral Layer Position

In the process of sheet metal design,The unfolding of sheet metal is used to guide cutting,nesting and production of sheet metal parts.So the correct lofting is an indispensable prerequisite for the layout of subsequent process and process.It can not only guarantee the accuracy of sheet metal parts,but also can improve the processing efficiency,reduce the consumption of the plate and save the cost.In this paper,based on the actual production needs,in order to improve the goals of the expansion precision and efficiency and considering the plate thickness,the paper studies the case of tube intersection and approximate expansion of spherical surface,and the corresponding fast expansion system is developed the tube sheet metal parts and the spherical expansion.The rapid unfolding system of tube sheet metal parts and spherical surface is developed by the research on the problem of the thickness treatment in tube and the approximate expansion of spherical surface.The main research contents of this paper include:the calculation of the position of the strain neutral layer;based on the characteristics of the neutral layer and the processing method of plate thickness,the mathematical modeling of the interface geometry information of the tube sheet metal parts is established and calculated by numerical method in MATLAB;the triangle line method is used to approximately expansion the spherical sheet metal;the parametric structure design of sheet metal parts and development of automatic expansion system;the system realizes the error analysis and output of the approximate expansion of the neutral layer sphere.In order to get the relatively precise lofting graph and considering the influence of relative bending rate on the position of the neutral layer,the system could achieve the function of calculation for location of the layer and mapped to the neutral lever.At the same time,for the convenience of users,the visual interface is used in the selection of the type of expansion and the input of parameters.For developable surface(pipe)sheet metal parts,the numerical solution method can be used to accurately calculate the coordinates of the points on the interface curve.For the development of non-developable surface(ball)sheet metal parts,the system can automatically select the best starting point and divide the mesh to meet the requirements of different sizes and different accuracy.In addition,the system can export the value of approximate expansion error in order to verify the feasibility of the method.In conclusion,this system can realize the sheet metal of the three-dimensional parameterized structure design,calculation for the position of the neutral layer and output,spherical approximate expansion error text output,the fast output of the lofting graph and a series of functions.In this paper,based on the influence of the change by the position of the layer on the expansion accuracy,studied of the mathematical model for sheet metal expansion,which is based on the expansion of the tube and the spherical sheet metal.The model is used to theoretical basis for development of the rapid expansion system,and provides a more precise layout drawing of sheet metal parts for the production.The development environment of the system is with NX UG 8,and Studio Visual 2010 and object-oriented C#programming language as the two development tool.