STRUCTURAL CHANGES ORIGINATING IN THE BLANK MATERIAL AT THE MOMENT OF COLLISION WITH TOOLING AND THEIR INFLUENCE ON THE QUALITY OF THE FINISHED WORKPIECE

Cette étude considère les conditions pour générer les changements de structure et leur influence sur le degré de déformation d'un tube avant la collision, sur la vitesse de collision et sur les propriétés physiques et mécaniques du matériau impacté. Les limites supérieures et inférieures pour la vitesse de collision qui permettent de déterminer les changements de structure ont été fixées. On montre l'influence de la vitesse sur la valeur des contraintes résiduelles et les dimensions finales de la pièce.The paper considers the conditions of generating structural changes and their dependence on the degree of tangential structural strain of a blank before the collision, on the collision velocity and on the mechanical and physical properties of the colliding materials. Lower and upper boundaries for the collision velocities determining structural changes are set. The velocities influence upon the value of residual stresses and upon the workpiece final dimensions is shown

Metallic behavior in the center of deformation when pulse-magnetic cropping an allowance of hollow billets

The mechanism of parting of hollow billets when pulse-magnetic loading is the concern of the paper. Much attention is given to investigation of the kinematics of the process of parting under various conditions of loading and different relations of geometrical parameters of a billet, inductor and die. With consideration for results of metallographic investigations the model of metallic behavior in the center of deformation has been proposed, which allows to control knowingly the process of pulse-magnetic cutting with the aim of the attainment of the required quality of products

Magnetic pulse deformation of tubes made of partially polymerised carbon fibre reinforced plastic

The paper describes impulse deformation of tubes made of partially polymerized carbon filled plastic in combination with aluminium rings. A mathematical model is proposed for investigation of two stages of joint deformation. The first stage involves impulse deformation of an aluminium ring combined with carbon filled plastic mass. During the second stage the kinematics obtained at the first stage is used to determine the stress-strain state of a carbon filled plastic tube by the finite-element method. Changes in the stress-strain state due to a number of technological parameters are also described

INFLUENCE OF THE SPREAD IN VALUES OF ALUMINIUM ALLOY DYNAMIC PROPERTIES UPON THE FINAL RESULTS OF MAGNETIC-PULSE STRAIN

Dans cette étude on fournit un modèle mathématique pour un procédé d'expansion de tubes par impulsion magnétique au moyen d'une approximation par la loi puissance de la courbe d'écrouissage dynamique [MATH]. La méthode par éléments finis permet d'analyser les déformations dues aux contraintes du matériau tubulaire dans le procédé d'expansion par impulsion magnétique et d'estimer l'influence de la dispersion des facteurs k et n sur les résultats de la déformation finale. Les limites de la dispersion des facteurs k et n ont été définis tous deux en fonction des résultats de tests dynamiques cités par d'autres chercheurs sur les alliages d'aluminium et les résultats obtenus par les auteurs.The paper provides for mathematical model of magnetic-pulse process for tubular blanks expansion by means of power approximation of the dynamic hardening curve [MATH]. Finite element method allows to analyse stressed strain of the blank material in the process of magnetic-pulse expansion and to estimate the influence of the spread in "k" and "n" factors on final strain results. Boundaries of the spread in "k" and "n" factors were defined both by the results of dynamic tests on aluminium alloys cited by other investigators and by the results obtained by the authors

Pulse-Magnetic Processing Technology when Making Parts and Units of Aerospace Engineering

Experience on using of pulse-magnetic processing of materials (PMPM) at the enterprises of the aero-space industry is presented. The emphasis is on the processes of hollow billets stamping. A complete list of technological processes mastered is available, advantages of these processes are outlined. The paper is illustrated with some examples of the concrete parts and units made with a help of the pulse-magnetic technology.On décrit l'expérience de l'utilisation du formage magnétique dans les entreprises de l'industrie aérospatiale. On parle surtout des processus du formage des piéces brutes creuses. On procéde à l'énumération de tous les processus mis en oeuvre, on décrit leurs avantages. Il y a quelques exemples de piéces et de sons-ensembles concrets fabriqués à l'aide de la technique magnétique