Energetic analysis of hard facing and weld cladding of an air powered drop hammer damaged ram

Abstract

This paper studies problems of hard facing of damaged and initially cracked mechanical engineering heavy parts of complex geometry such as large rams of air powered drop hammers. During long-term exploitation, these parts are subjected to thermal fatigue due to cyclic temperature changes and variable impact compression. Taking into consideration high ram costs and difficulties to purchase ram, the necessity of its reparation becomes obvious. The choices of the most suitable technologies of hard facing and welding of an initially cracked ram are also studied here. Besides the techno-economic analysis, an energetic analysis is performed as an additional criterion in assessment of the proposed technology.reparation of the biggest rams of the mass of about m UK = 6000 kg, including hard facing of initially cracked and damaged operating surfaces of the rams.Note that, following the proposed technology, two rams have been successfully repaired so far. One of them has been used since 2002 and the other since 2005, which is significantly longer than the warranty period given by the manufacturers. Working environment for a ram of air powered drop hammerThe ram (figure 1) is exposed to impact compressive loads, and partially also to the temperature gradient, i. e. to the thermal stresses, caused by an unbalanced temperature field [1][2][3][4][5][6]. This intensively loaded mechanical part operates under very complex conditions since, during exploitation, it is exposed to mechanical and thermal loads of high intensity. After a long period of operation, i. e. after a high number of repeated cycles, cracks are observed on the ram, as shown in figure 1.

Performance of Fe-based hardfacings on hot forging die: experimental, numerical and industrial studies

“…Hardfacing is currently the most popular technology and an economical method when it comes to repairing damaged dies and molds so that they may be put into operation again [9]. The fundamental principle of the hardfacing technology is the creation of a wear resistant layer on to the base material via deposition of the desired material [1,10]. Three types of hardfacing alloys, namely Cobalt base, Nickel base and Iron base, are the most frequently used materials for hardfacing while having different composition and different welding process parameters.…”