Analysis of wear-out behavior of MPM mill mandrels and methods of extension of their service life

The analysis of the equipment has been performed, basic design features have been identified and the continuous MPM mill (Multistand Pipe Mill) mandrel assembly make-up has been described. Based on the study of bibliography, the most distinctive types of wear-out and operating conditions have been examined. Mandrels operating conditions and their failure reasons have been defined and described. Instrument durability problems have been designated. The necessity for a reasonable approach to mandrel length calculation has been demonstrated. Calculation features of the mandrel length for pipe continuous rolling have been analyzed and essential disregarded factors were defined, i.e. rolling ratio, distance between a continuous mill and an extraction-sizing mill, a location of the most wearable area, straining conditions, which eventually affect the mandrel assembly and the operational life of other equipment. Based on the trial data the wear-out features of a continuous MPM mill mandrel assembly have been analyzed. The analysis of the effect of various factors on service durability of the mandrel working part has been provided. Practicable possibilities for the extension of the operational life of the equipment have been considered. Recommendations to enhance the rolling instrument durability have been given. Basic prospective trends to enhance the service life of the mandrel assembly of a continuous MPM mill installed at the plant have been identified.