REPAIRING THE MAIN SHAFT OF DRYER TOASTER

Abstract

Introduction. The sources of damage and wear of the main shaft of the drier toaster are analyzed. The repair know-how and welding operations execution limitations which must be considered when developing the technique providing the restoration of the structure performance features are studied. The work objective is to develop a technique of repair without dismantling for the main toaster shaft. To solve the task, a design repair structure was installed, and postwelding operations that meet the engineering and regulatory requirements for this structure were performed.Materials and Methods. In “Kompas 3D” software, the following models were developed: integral shaft (project shaft design); damaged shaft as a result of long-term operation (more than 15 years); and damaged shaft with a welded repair structure. Numerical simulation of the stress-strain state (SSS) was carried out.Research Results. Software for the computational modeling of the repair structure SSS is developed. The repair shaft structure in which the maximum stresses do not exceed the shaft stresses in the project design is obtained using the model. To eliminate the aggressive medium effect on the corrosion fatigue strength of the shaft, an insulating method is used. A technique for mounting the repair structure to the shaft allowing for the outrun limitation 0.12 mm is developed.Discussion and Conclusions. Torsion shafts damaged deeply by wear and corrosion are considered. To restore their structural integrity, it is worthwhile using the following complex of techniques:— constructive (consists in the installation of optional parts that compensate for insufficient strength, and provides a reduction in stress concentration in the most loaded zones);— processing (reduces residual welding stresses due to the reasonable sequence of deformation that contributes to generating favorable residual compressive stresses);— isolation (is based on the application of anticorrosion coatings).The economic expediency of the developed repair technique is obvious. The repairing of the shaft without dismantling costs 180,000 rubles, while a new shaft costs 3.8 million rubles.