The tensile flange process is a common operation in metal forming. Where the shape of the mandrel and matrix directly on the metal causes deformation, it is associated with low or no flow of materials and is normally used to increase rigidity and strength at the internal surfaces and to form tensile flanges in high pressure switches and others. Industries such as automobiles are used. In this research, the tensile flange process is expressed by using a mechanical press on 304 stainless steel with a thickness of 3 mm with six holes on the wall of the tensile flange used in the body of the PGL medium pressure sectional product. Uniform deformation of the inner hole and distortion around the six holes are two important defects in this sample. Reverse engineering based redesign with the help of LS-DYNA software has been simulated using the nonlinear explicit finite element method and the simulation and experimental results have been compared.
1. Introduction
Reverse engineering is used to build inside some parts in the electrical industry. Analysis and prediction of changes in the part is one of the most important factors in reducing the costs of continuous production of parts and products without the use of analytical software. Be. Metal shaping simulation helps reduce cost and production time. The main parameters affecting the forming process such as part geometry, mold design, material selection, process type and final quality control can be examined with this software. In general, engineers want to answer the following questions by using software: Can the part be produced? Which areas of the part are damaged? In which part of the wrinkle does it occur? What is the forming curve?
According to Figure 1, there are generally three types of working flanges and it is mainly used in industry. Straight flange is a common type of flange. The straight flange has no curvature. Issues and problems related to the direct return spring flange. Closed tolerances are not specified except to increase component performance. Changes in the improvement of elastic properties or spring bounce are important. These results are obtained from changes in material properties.
The main difference between the flanges is the curvature of the flange. Concave flanges are called tensile flanges because the materials are formed in a tensile state. In a tensile flange, the strain changes from zero on the neutral axis to a maximum size at the flange edge, so any rupture will start from the flange edges if left unchecked and depending on the strength of the material.
A convex flange is called a pressure flange. In this process, the material is compressed or contracted. The material in the compression flange is reduced in length. In the case of a compression flange, a large compressive strain is created.
Some researchers have studied flanges in the past. They have studied the process of forming tensile and compressive flanges on aluminum parts using fluid. It has also examined the relationship between the fracture limit in the tensile flange and the properties of the material. Ahmadaghloo et al. [2] investigated defects such as wrinkles and tears in the formation of sheet metal, including tensile flange and deep tensile. In this case, it is possible to cause wrinkles in the flange and other stretched areas due to compressive stresses. Fracture is due to the pressure caused by the sheet holder, which can be improved by changing the various designs of the hanger. Mr. Wang [3 and 4] described the general analytical method for the two processes of tensile and compressive flange. Both models effectively express the deformation of the flange process. However, the process resulting from analytical formulas is difficult for engineers to define and shape the initial sheet geometry. These two models can not express the effect of primary anisotropy in the flange process.
The aim of this research is to introduce effective tools for numerical simulation of tensile flange process. In such a way that the initial sheet with the inner hole changes the shape of the inner hole with the vertical movement of the mandrel. Six holes are embedded in the flange wall. The strains around the hexagonal holes are larger than the rest of the specimen. Non-uniform deformation is obtained in the inner hole and the outer diameter of the sample.
The location of the six-hole traction flanges where 6 M6 screws are located to connect and hold the bushings on the body of the PGL machine is shown in Figure 2.
2. Numerical model
The numerical model of the sample was performed using the nonlinear explicit finite element method by Diana LS software. In this paper, the diameter of the mandrel is 100 mm, the diameter of the inner hole of the matrix is 106 mm and the radius of the mandrel is 3 mm. The thickness of the sheet is 3 mm, the outer and inner diameters of the primary sheet are 141.5 and 73 mm, respectively, with six holes on the wall of the primary sheet. The sheet holder was not used due to the change in the position of the six holes. Table 1 shows the measured positions according to Figure 3. Parameters a and b represent the outer radius and the inner hole radius.
Figure 3- Parametric dimensions of the sample before the tensile flange
Table 1: Measured positions of the primary sheet before the tensile flange
Measured positions (mm)
g f e d c b a
2 5.2 9 51 59.49 36.5 70.75 Sample
Tool surfaces are grided using rigid shell elements. The use of the properties of the experimental sample materials with yield stress Mpa 329.35Rp0.2 and final tensile stress Mpa = 643.17 Rm allows us to define the properties of the initial sheet. After setting the tools and properties of the raw material, Diana LS solvent is used. But before that, friction properties, anisotropy coefficients, recovery level, compatibility properties must be defined. Friction coefficient for simulations = 0.125