Research On Several Key Questions In The Variable-Data Forming Principle And Equipment Design Theory

Variable-data forming (VDF), manufacturing works or rough parts directly by changing the material cross-section size and shape, is a technology and method which is crossed by machine building with rolling. The technology, having the features of improving material properties and saving material and high productivity, etc, is a promising process in the 21th century. Some key questions in the forming principle and equipment design theory has been studied in the paper.The concept of VDA has been put out and the basic phenomenon and law of that have been researched and the theorical system of that has been set up. The biting condition and the relationship of contact angle with biting angle and with bite condition have been built. The metal moving form, speed law, deforming rate formula in variable-data farming have been studied. The affecting law of draught on biting angle and contact angle and the length of deforming zone have been studied. The judgment condition of rolling penetration and the formula of least reduction in pass have been built.The slip law of metal in the deforming zone and the change law of contacting angle with the works thickness curve slope and the effect of that on the metal in the deforming zone have been studied. The formula of forward slip and backward slip and section change coefficient has been built. The friction state and principle in the deforming zone of variable-data farming have been analyzed. With the theory of forecast displacement, the friction principle on neutral flow plane has been studied. The factor affecting friction and slip has been discussedBased on Upper-bound theorem, the calculating method of dynamicsparameter of load on equipment has been found. By building deformation zone boundary function and cross-section speed function, the allowable velocity field and strain rate field of deformation zone bave been studied. The calculation method of plastic deformation power in deformation zone and shear power on the speed discontinuous surface and friction power on the friction surface bave been studied. The Upper-bound power calculation formula, satisfying Mises yield condition and Levy-Mises flow rule, has been put forward. The formula of forming force and moment has been obtained finaly. The accuracy of forming force calculation formula is proved by test.The basic law of metal spread has been studied. The form and cause of that have been analyzed. Under the spread branch zone hypothesis and based on the condition of minimum flow resistance and volume constant, the spread formula, which is satifying application by comparing test data with model data, has been put forward,.The concept of V-H one-pass rolling, by which the three-dimensional deformation is turn to double two-dimensional deformation to control and form, has been put out. The technology and theory and math-model and the phenomena such as works shape and forming stability of V-H one-pass rolling have been studied. The shape simulation to test V-H forming theory has been completed. The V-H forming theory has been set up.The mapping relationship of concurrent step design and the judging rule composed by functionality and information and circulation have been put out. The mechanism shape of V-H forming equipment has been studied. The concept of stress-loops has been put forward and used to improve equipment rigidity. The power type and control shape and math formula have been studied. The accuracy and practicality of stress-loops improving equipment rigidity have been checked by the finite element method. The shape and size of rolls could be obtained. The feasibility and accuracy of technologic method of V-H forming are shown by test. The key equipment of V-H forming has been developed.