Search

Current frequency is one of the most important parameters that must be analyzed and optimized for the analysis and design of electromagnetic forming process, and its effects on the electromagnetic forming process are very complicated. The influence of frequency on electromagnetic tube compression has been investigated by means of the sequential coupling numerical simulation. The delaying and the total time of the forming process prolong with the lowering of the frequency, and the optimum frequency is found that corresponds to the largest deformation and the greatest plastic strain energy of the tube. There is a special range around the optimum frequency, where the corresponding deformations are similar and the relative skin depth is between 0.61 and 0.70. The maximum energy efficiency of the electromagnetic tube compression is 13.76% in this work, which is corresponding to the optimum frequency.

A sequential coupled field analysis of electromagnetic tube compression process has been performed by using the finite element method (FEM). A 2D axisymmetric electromagnetic model based on the magnetic vector potential is proposed for the calculation of magnetic field and magnetic forces; and Newmark integration method is used to calculate the dynamic plastic deformation of tube in the mechanical model. In each time step during the simulation, the transient magnetic forces acting on the tube are obtained from the electromagnetic model, which are then used as input load to the mechanical model. According to the tube deformation calculated, the geometry of the electromagnetic model is updated. Therefore, the sequential coupling simulation is realized between the electromagnetic model and the mechanical model, whose results are more accurate than the loosing coupling simulation method. The radial deformation along the outer generatrix of deformed tube wall is presented as a function of time and the plastic strain energy of electromagnetic tube compression is analyzed.

Electromagnetic forming is a kind of high energy rate forming; in which magnetic pressure analysis is the foundation of theoretical analysis. Usually equivalent methods are used to resolve any problems, but because of the limitations of the calculation methods, only the average force which acts on the workpiece can be obtained. Especially, the tolerances at the end of the workpiece are higher, which results in great difficulties in the deformation analysis of the workpiece. This paper carries out a numerical simulation of the magnetic pressure acting on the workpiece during electromagnetic bulge forming by use of the FEA software ANSYS. The boundary conditions of the analysis model are established on the basis of theoretical analysis of the magnetic field properties. Through measuring the magnetic induction intensity between the coil and the workpiece, the simulative results are proven to be accurate. This is the first time that the magnetic pressure distribution in the thickness direction of the workpiece has been explored through FEM.

In this paper, the relationship between side pressure, stretching force and the section distortion of LY12M hat-section profiles in the rotary draw bending process with stretching force are studied. The section precision of the rotary-drawn bent parts is well improved by the return rotary draw bending process, and lays the foundation for practice.

Curved flanging is a common forming process in sheet metal forming, but its deformation characters are different from that of plate flanging. Based on experimental results the paper studies and analyzes the characteristics of the deformation, the stress properties, the strain distribution and various factors influencing the deformation in curved flanging. The main principles and methods of die design are also given, based on the quality analysis in the paper.

There often appears longitudinal cracking in deep-drawn austenitic stainless-steel parts that is due mainly to the presence of tangential stress and to the structure of the metal. In this paper, the X-ray diffraction (XRD) method is used to test and analyse the residual tangential stress and the content of induced martensite transformation in two kinds of stainless steel under different deformation conditions. Based on the results, a compound technology of smaller clearance drawing and ironing is presented. The results of testing verify that deep stainless-steel cups with fewer stages of deformation, a lesser number of annealings and no longitudinal cracking can be produced through the use of this technology, which latter also can save energy and reduce pollution.