REPAIRING THE MAIN SHAFT OF DRYER TOASTER
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.