The Research On The Limit Parameters For One-Operation Forming The Conical Part In Deep Drawing

Deep drawing is a typical method to make uncork hollow part of thin wall, and this method is significantly important in the industrial practice. The range of the part made by this method is quite wide, such as the cylinder part, box part, conical part, spherical part and even large part of complicated camber shape, for example automobile overcast part. The conical part is a sort of part whose shape is relatively simple in camber part, but now it is not found for a way to calculate forming limit parameters of the conical part according to forming mechanism of the conical part. Therefore, on the basis of analyzing the disciplinarian to form the conical part, to study the limit conditions and present method calculating limit to form the conical part provides important significance and enriches foundation of blanking and accurately calculating forming limit of the conical part in practical producing.Research idea of this paper is that conical wall divorced from punch is formed by action of the pull during forming process of the conical part and the theory analysis, experiment method and finite element numerical simulation are adopted the research contents, in as follow:(1) In this paper, sheet in forming process is divided into flange die horn region side-wall and punch horn region. The strain and stress on each region are thoroughly analyzed by using finite element simulation, the theory analysis, gridding experiment method. First the first time, from point of view of deformation mechanics, the deformation manner, the deformation characteristic and the deformation mechanism during the forming process are determined, so that the forming disciplinarian of the conical part is revealed and foundation for making certain formation limit is established.(2) The forming process of the flange is simulated by the finite element method and the deformation characteristic of the flange is verified by simulation results and that the formula of the large radial stress at inner brim of the flange is educed by regressing simulation results, so that the formula of the large radial stress pulling the flange into die horn is established and the formula is validated by experiment. The deformation manner the deformation characteristic and the deformation mechanism during forming the side-wall is discussed by the way of tracking the place of point and measuring change ofstrain radio on the original sheet using grid experimentation, and that gives profound understanding on forming rule of the side-wall. Thereby, analysis on rupture and wall-wrinkle is upbuilt on the basis of the deformation mechanics.(3) According to idea that the pulling force makes the side-wall form, the mechanism of the side-wall forming is that latitudinal deformation comes about by longitudinal stress ,the latitudinal deformation makes the points on the sheet to produce radial displacement, and the radial displacement results in the points leaning the punch to form the side-wall. So far, the mechanism of the side-wall forming is more definitive and developmental. On the base above, the expression of relationship between radial displacement and the longitude stress is educed by plastic theory. Furthermore, On the base determining dangerous section of rupture, relationship between rupture limit load of conical parts and rupture limit load of cylindrical parts is presented by means of theoretical analysis and regressing test data. These research works theoretically provide essential condition to determine the limit deformation conditions.(4) According to similarity of the conical part forming and the cylinder part drawing, the limit conditions of making the flange form is proposed, and the formula to calculate the limit coefficient of the conical part forming by using limit drawing coefficient of the cylinder part is educed. According to experiment data i.e. the radial displacement leaning the punch on the side-wall, it is assumed that the key-point leaning the punch is the point cling to the die horn on original sheet. By analysis on mechanism of the radial displacement of the key-point leaning the punch, the concept of permissible radial displacement and the largest radial displacement leaning the punch is first brought forward and these formulas are educed. On this basis, the limit condition of the side-wall forming is presented, and the formula for calculating maximal forming depth of the side-wall is derived.(5) The limit coefficient of the conical part forming is changed into forming depth when whole flange region becomes the side-wall. Through the formulas calculating maximal forming depth of the side-wall, for first time in theory, the limit and range of parameters for one-operation forming the conical part are given, and the method to judge one-operation forming the conical part is presented. Calculating results on the limit parameters of one-operation forming the conical part indicate that only just in a definite range of relative conical diameter, the whole flange region is able to form the side-wall. Meanwhile, the limit and range of parameters one-operation forming the conical part are validated by the experiment data.In this paper, the knowledge of some key questions on the conical part forming is deeply understood by analyzing the forming disciplinarian of the conical part, so that it has significant meaning in research work and would be helpful for solving these questions. The limit and the determining method for one-operation forming the conical part obtained by analyzing the forming disciplinarian of the conical part can provide practice with a reliable basis of judging one-operation forming the conical part in producing conical part.