Research of Electric Contact Welding by a Wire at Restoration of Details of Cars

Abstract

The article presents the results of a study of electrical contact welding with a wire when restoring the working surface of machine parts.In order to test the effectiveness of the developed measures to prevent interlayer fractures, the samples after multilayer welding and rough grinding were subjected to embossing with an impact energy of 6 J. The thickness of the layer after rough grinding was 1.5 mm. The depth of hardening, determined by measurements of microhardness, was 3.5... 4 mm. Metallographic studies of interlayer fractures of the multilayer coating did not reveal. It was found that the cause of continuity defects in the "scallops"of the welded metal layer is the increased current density in the cross section of the upset wire from the side of the previously welded roller. This leads to local overheating of a part of the filler metal, its squeezing out from under the electrode and cooling on the surface of the previously welded bead in the absence of forging. An increase in the width of the working part of the roller electrode over a certain value, depending on the diameter of the filler wire, the amount of its upsetting, the welding step, prevents the upsetting wire from being squeezed out from under the electrode and eliminates the reasons for the formation of these defects. An increase in the torque of the roller electrode leads to an increase in the strength of the formed welded joint due to an increase in the relative axial deformation of the filler wire. It was found that an increase in the relative axial deformation of the filler wire leads to a slowdown in the rotation of the roller electrode. This makes it possible to control the relative axial deformation of the filler wire directly during the welding process by counting the number of revolutions of the roller electrode and the part.