| Sheet metal, rod, wire, tube, and other rolled-steel shapes all can be processed by shearing process, which is important one in the stamping productions. Sheet metal shearing process is most widely used and is the simplest one of all shearing processes. It can be used as preliminary process for bending, deep drawing, bulking, flanging and other complicated forming processes. Also, using this process, high precision parts can be obtained directly by determining the parameters of the dies properly. The sheet metal shearing process is very complicated since the deformation is focused on the small zone of the sheet metal and ended with fracture occurrence. So, before studying and researching on the sheet metal process, there are many basic problems to be solved, such as measurements of geometrical parameters, remeshing technique in FEM simulation, fracture criterion in line with the practical circumstance and so on. The theoretical studies on the sheet metal shearing process are rare due to these difficulties, so the development of stamping production is limited. The more widely this process is used and the higher requirement for technology, the higher the quality of stamping part is required. Therefore, the theoretical studies and researches on the sheet metal shearing problem are significant and imperative.The basic theories and preliminary techniques in FEM simulation and experimental researches on the sheet metal shearing processes have been done, which are described as below.The analogy principle is used to explain the requirement that must be met when the punch load is proportional to the sheet thickness. The further finite element analysis and experimental research can be guided by this conclusion. Further, the shearing model in accord with cyclical symmetry condition is analyzed, and the simplification method is presented. It is pointed out that many sheet shearing and blanking problems are close to or are in accord with the cyclical conditions, so they can be simplified into cyclical problems. The calculations of FEM can be decreased greatly by this method, and the symmetry shape of boundary can be chosen freely according to requirement.A new remeshing technique is presented for the plane sheet shearing problems and axisymmetry on the basis of the principle of large deformation elastic-plastic FEM. In the technique, the transmission between the old grids and new ones are treated properly based on the ANSYS software by using ANSYS parameter design language called APDL. It can be preliminary basis of FEM simulation on sheet shearing process. The calculation results have proved that this remeshing technique is concise and easy to carry out and the calculation accuracy is reliable.A displacement sensor of strain foil is designed aiming at the sheet shearing and blanking processes. The measurement range of the displacement can be adjustable in accordance with requirement and the relative accuracy of the displacement is not changed. The displacement measurement can be carried out in shearing and fine blanking processes for different thickness of sheet metal by using the sensor together with the data-acquisition system. The experimental devices of sheet shearing are fixed on the material experimentalmachine. The displacement sensor is suitable to the short range of measurement and it is basis of experimental researches on the sheet metal.On the basis of above preliminary researches, the sheet metal shearing process is analyzed by using large deformation elastic-plastic FEM and experimental method.Firstly, the distributions of strain and stress, for all material points at any deformation zones, lines and points, can be obtained at any instant during the whole shearing processing by FEM. They are considered as the basis of further studies on the sheet metal shearing process.Secondly, the method to determine the optimum clearance is proposed, according to the orientation of maximum shearing stress on the special lines and based on development law of the fracture and experimental results. Al...
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