Temperature modes and critical velocities when drawing the wire

详细

When producing rod and wire wares, residual stresses are formed. This phenomenon is caused both by plastic deformation and by possible thermoplastic deformation, which appears due to contact heating the metal ware surface due to external friction forces. Undesirable residual stresses in surface layers affect the accuracy of metal wares and increase their failure probability, which is observed in the practice of drawing production. In this study, a procedure is proposed to determine the contact heating conditions from the formation prevention criteria of residual stresses. Based on thermoelasticity equations, temperature modes leading to the appearance of thermoplastic deformations are established. Critical values of the temperature difference between the drawing wire surface and the center, at which the wire surface layers transform into the plastic state with the subsequent formation of residual stresses, are determined. Limiting drawing velocities for a series of nonferrous metals (copper, zirconium, and titanium), which, if exceeded, will lead to undesirable residual stresses in the drawn wire, are determined. To increase the critical velocities, it is recommended to implement the hydrodynamic (fluid) friction mode conditions when producing metal wires.