Abstract:

Calculated analysis of the extraction of axisymmetric hollow products from low carbon steel using a special profile deforming tool were carried out by the Finite Element Method. An elastic-plastic model of the workpiece metal was used. Coulomb friction, hardening, deformation rate and thermal effect during cold forming are considered. A special profile of the tool is a wavy surface, which is formed by the intersection of tori with the same diameter of the section, located with a certain step. Special profile of the Matrix and the clamp provided a decrease in the effect of friction on the drawing force. The special profile punch creates a pulling force behind the wall of the deformed workpiece in the gap between the matrix and the punch due to the filling of cavities with metal on its side-surface. Unloading of the bottom of the workpiece occurs by the amount of pulling force. The smoothing of the protrusions on the inner surface of the deformed workpiece is carried out during the reverse movement of the punch of a special profile and removing the product. The use of a special profile tool has reduced the number of draw transitions for low-carbon steel products by half.  At the same time, it was possible to draw with thinning the wall, which provided a decrease in the wall thickness variations. Possibility of extraction by a punch with a radius of rounding, which is two times less in comparison with the extraction of a traditional tool. This eliminates the additional operation of calibrating products after drawing. For the considered options for drawing with different gaps between the die and the punch, the dependences of the drawing forces, the forces on the clamps and the forces of removing products from the punches are established. The stress-strain state of the workpieces and the temperature of the deformed metal were revealed. Particular attention is paid to axial tensile stresses, which are the main reason for the separation of the bottom of the product. The shape and dimensions of the products after drawing are determined.

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