Analyzing the techniques for restoring crankshafts of automotive vehicles

Abstract

Characteristic defects of internal combustion engine crankshafts of automotive vehicles include wear of friction surfaces – journals, faces, grooves and threads, – as well as residual deformations and fatigue cracks. To eliminate defects, crankshafts are repaired using technological operations to restore the shape and location, linear and angular dimensions, as well as roughness, wear resistance and fatigue resistance of elements and surfaces. To analyze the restoration techniques of crankshafts of automotive vehicles the operating conditions, the authors considered the main defects and types of surfacing and spraying applied by means of electric arc, gas-flame, detonation, and plasma (induction and plasma-arc) methods. The authors note that to meet reliability requirements, the restored parts should have a ratio of hardness (НRС_в/НRС_н) and fatigue strength (G_-1B/G_-1H) higher than one as compared to new parts. However, no crankshaft restoration technique fully meets this requirement, because the wear resistance of new crankshafts in most cases is higher than that of restored parts. Based on the analysis of crankshaft restoration techniques, the authors determined the following effective ones: the finishing antifriction non-abrasive treatment (FANT) with the use of antifriction, wear-resistant and solid lubricant coatings applied to the parts using various methods. This technique increases wear and corrosion resistance, resistance to fatigue wear, and improves the running-in of the rubbing machine parts.